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  • gene expression
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  • 1990-1994  (2,284)
  • 1955-1959  (284)
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  • 1
    Electronic Resource
    Electronic Resource
    Butyrate-induced reactivation of the fetal globin genes: A molecular treatment for theβ-hemoglobinophaties (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 133-137 
    Details
    ISSN: 1420-9071
    Keywords: Fetal hemoglobin ; sickle cell anemia ; β thalassemia ; butyrate ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The inherited β-hemoglobinopathies (sickle cell disease and β thalassemia) are the result of a mutation in the adult (β) globin gene. The fetal globin chain, encoded by the γ globin genes, can substitute for the mutated or defective β globin chain, but expression of the γ globin gene is developmentally inactivated prior to birth. Reinducing expression of the normal fetal globin genes is a preferred method of ameliorating sickle cell disease and the β thalassemias. Stimulation of as little as 4–8% fetal globin synthesis in the bone marrow can produce 〉20% fetal hemoglobin in the peripheral circulation, due to enhanced survival of red blood cells containing both sickle and fetal hemoglobin, compared to those containing sickle hemoglobin alone. Butyric acid and butyrate derivatives are generally safe compounds which induce fetal hemoglobin production by stimulating the promoter of the fetal globin genes. An initial trial with the parent compound, delivered as Arginine Butyrate, has demonstrated rapid stimulation of fetal globin expression to levels that have been shown to ameliorate these conditions. Phase 1 trials of an oral butyrate derivative with a long plasma half-life have just begun. These agents now provide a specific new apporach for ameliorating these classic molecular disorders and merit further investigation in larger patient populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989417
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  • 2
    Electronic Resource
    Electronic Resource
    Altered proteoglycan gene expression and the tumor stroma (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 447-455 
    Details
    ISSN: 1420-9071
    Keywords: Proteoglycan ; chondroitin sulfate ; decorin ; gene expression ; tumor stroma ; DNA methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Tumor stroma is a specialized form of tissue that is associated with epithelial neoplasms. Recent evidence indicates that significant changes in proteoglycan content occur in the tumor stroma and that these alterations could support tumor progression and invasion as well as tumor growth. Our main hypothesis is that the generation of tumor stroma is under direct control of the neoplastic cells and that, via a feedback loop, altered proteoglycan gene expression would influence the behavior of tumor cells. In this review, we will focus primarily on the work from our laboratory related to the altered expression of chondroitin sulfate proteoglycan and its role in tumor development and progression. The connective tissue stroma of human colon cancer is enriched in chondroitin sulfate and the stromal cell elements, primarily colon fibroblasts and smooth muscle cells, are responsible for this biosynthetic increase. These changes can be reproduced in vitro by using either tumor metabolites or co-cultures of human colon carcinoma cells and colon mesenchymal cells. The levels of decorin, a leucine-rich proteoglycan involved in the regulation of matrix assembly and cell proliferation, are markedly elevated in the stroma of colon carcinoma. These changes correlate with a marked increase in decorin mRNA levels and a concurrent hypomethylation of decorin gene, a DNA alteration associated with enhanced gene expression. Elucidation of decorin gene structure has revealed an unexpected degree of complexity in the 5′ untranslated region of the gene with two leader exons that are alternatively spliced to the second coding exon. Furthermore, a transforming growth factor beta (TGF-β)-negative element is present in the promoter region of decorin gene. This regulatory domain is likely to be implicated in the silencing of decorin gene by TGF-β and may contribute to the regulation of this matrix gene in the tumor stroma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01923588
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  • 3
    Electronic Resource
    Electronic Resource
    Phlorizin treatment of diabetic rats partially reverses the abnormal expression of genes involved in hepatic glucose metabolism (1993)
    Springer
    Diabetologia 36 (1993), S. 292-298 
    Details
    ISSN: 1432-0428
    Keywords: Diabetes mellitus ; phlorizin ; glucagon ; hepatic glucose metabolism ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Liver insulin resistance and glucagon-stimulated hepatic glucose production are characteristics of the diabetic state. To determine the potential role of glucose toxicity in these abnormalities, we examined whether phlorizin treatment of streptozotocin-diabetic rats resulted in altered expression of genes involved in key steps of hepatic glucose metabolism. By inhibiting renal tubular glucose reabsorption, phlorizin infusion to diabetic rats induced normoglycaemia, did not significantly alter low circulating insulinaemia, but caused a marked decrease in hyperglucagonaemia. Glucokinase and L-type pyruvate kinase mRNA levels were reduced respectively by 90% and 70% in fed diabetic rats, in close correlation with changes in enzyme activities. Eighteen days of phlorizin infusion partially restored glucokinase mRNA and activity (40% of control levels), but had no effect on L-type pyruvate kinase mRNA and activity. In contrast to the glycolytic enzymes, mRNA and activity of the gluconeogenic enzyme, phospoenolpyruvate carboxykinase were increased (10- and 2.2-fold, respectively) in fed diabetic rats. Phlorizin administration decreased phospoenolpyruvate carboxykinase mRNA to values not different from those in control rats, while phospoenolpyruvate carboxykinase activity remained 50% higher than that in control rats. The 50% rise in liver glucose transporter (GLUT 2) mRNA and protein, produced by diabetes, was also corrected by phlorizin treatment. In conclusion, we propose that phlorizin treatment of diabetic rats may induce a partial shift of the predominating gluconeogenesis, associated with hepatic glucose overproduction, into glycolysis, by correction of impaired pre-translational regulatory mechanisms. This could be essentially mediated through improved pancreatic alpha-cell function and subsequent lowering of hyperglucagonaemia. These observations suggest that glucagon-stimulated hepatic glucose production may result, in part, from glucose toxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400230
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  • 4
    Electronic Resource
    Electronic Resource
    The glucocorticoid receptor precludes the binding of a transcriptional repressor protein to the long terminal repeat of the mouse mammary tumor virus (1993)
    Springer
    Molecular and cellular biochemistry 122 (1993), S. 25-37 
    Details
    ISSN: 1573-4919
    Keywords: glucocorticoid receptor ; MMTV ; transcription factors ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The long terminal repeat (LTR) of the mouse mammary tumor virus was used as a template to examine the dual binding parameters of the glucocorticoid-receptor (GR) and a repressor protein termed Inhibitory Factor 1 (IF1). The roceptor binds specifically to the glucocorticoid response element and precludes the binding of IF1 to its juxtaposed binding site within the LTR. When the two DNA targets are separated by the insertion of an additional 52 base pairs, coincident binding of both proteins is observed. Gel retention assays reveal three distinct nucleoprotein complexes. The first complex consists of the receptor and the LTR, the second is comprised of IF1 and DNA and the third is a multiprotein-DNA complex consisting of the GR, IF1 and DNA, migrating at a higher molecular weight position. The inhibition of IF1 binding by the presence of prebound GR leads to the repression of transcription of juxtaposed genes. The GR may act to block access of a sequence, used by the cell to titrate repressor proteins and facilitate the onset of gene expression. (Mol Cell Biochem122: 25–37, 1993)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925734
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of pregnancy-specific β1-glycoprotein genes in hematopoietic cells (1993)
    Springer
    Molecular and cellular biochemistry 122 (1993), S. 147-158 
    Details
    ISSN: 1573-4919
    Keywords: PSG transcripts ; gene expression ; PCR ; T lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The presence of PSG in blood cells has been demonstrated by immunohistochemical staining. However, the origin of these proteins is not known. This report examines the expression of the PSG genes in different types of freshly isolated blood cells. RNA isolated from bone marrow and peripheral blood cells of healthy individuals was analyzed for PSG transcripts by reverse transcriptase-polymerase chain reaction using synthetic oligonucleotide primers specific for the PSG genes. The level of expression of the PSG genes in different types of cells exhibited significant individual variation. Trace amounts of PSG transcripts could be detected in polymorphonuclear cells (PMN), monocytes and B lymphocytes while T lymphocytes always contained the highest level of transcript. The expression of PSG genes in the blood cells apparently was not affected by the method of isolation nor by overnight culturing of these cells except in the case when lymphocytes were separated by rosetting with sheep red blood cells. All reported PSG transcripts were detected in blood cells. Both type I and type II transcripts of the PSG genes were detected in blood cells with the exception of type II transcript of PSG5 and PSG11 which were only found in the placenta. Tissue specificity in the expression or alternative splicing of some of the PSG family members was implicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01076099
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  • 6
    Electronic Resource
    Electronic Resource
    Expression of an ABA-responsive osmotin-like gene during the induction of freezing tolerance in Solanum commersonii (1993)
    Springer
    Plant molecular biology 21 (1993), S. 729-735 
    Details
    ISSN: 1573-5028
    Keywords: ABA ; cDNA cloning ; freezing tolerance ; gene expression ; osmotin-like protein ; Solanum commersonii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated a cDNA (pA13) of an ABA-responsive gene from suspension cultures of Solanum commersonii. The deduced amino acid sequence of pA13 cDNA revealed 89 and 91% identity with tobacco osmotin and tomato NP24 protein, respectively. The accumulation of the transcript corresponding to pA13 cDNA was regulated by ABA, cold temperature, and low water potential treatments. Cold-induced accumulation of the pA13 transcript was partially suppressed by fluridone, an ABA synthesis inhibitor, and the suppression was restored by exogenous ABA application. The transcript corresponding to pA13 also accumulated in an organ-specific manner in response to ABA or cold treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014558
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  • 7
    Electronic Resource
    Electronic Resource
    Semi-constitutive expression of an Arabidopsis thaliana α-tubulin gene (1993)
    Springer
    Plant molecular biology 21 (1993), S. 937-942 
    Details
    ISSN: 1573-5028
    Keywords: α-tubulin ; Arabidopsis ; β-glucuronidase ; gene expression ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Arabidopsis tissues, the pool of tubulin protein is provided by the expression of multiple α-tubulin and β-tubulin genes. Previous evidence suggested that the TUA2 α-tubulin gene was expressed in all organs of mature plants. We now report a more detailed analysis of TUA2 expression during plant development. Chimeric genes containing TUA2 5′-flanking DNA fused to the β-glucuronidase (GUS) coding region were used to create transgenic Arabidopsis plants. Second-generation progeny of regenerated plants were analyzed by histochemical assay to localize GUS expression. GUS activity was seen throughout plant development and in nearly all tissues. The blue product of GUS activity accumulated to the highest levels in tissues with actively dividing and elongating cells. GUS activity was not detected in a few plant tissues, suggesting that, though widely expressed, the TUA2 promoter is not constitutively active.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027126
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  • 8
    Electronic Resource
    Electronic Resource
    Identification of cis-acting elements involved in the regulation of the pathogenesis-related gene STH-2 in potato (1993)
    Springer
    Plant molecular biology 22 (1993), S. 279-291 
    Details
    ISSN: 1573-5028
    Keywords: wounding ; elicitor ; plant defense ; gene expression ; tuber ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have characterized a genomic clone containing the potato pathogenesis-related genes STH-2 and STH-21. The two genes are found 4 kb apart on the same chromosome and their sequences are highly similar. They present the same transcriptional orientation and are both interrupted by a single intron. A chimaeric gene consisting of 1015 bp of 5′-flanking sequence and part of the first exon of STH-2 fused to the bacterial β-glucuronidase gene was highly-expressed in tubers of transgenic potato plants after wounding and elicitor treatments. The levels of activity observed in these transgenic plants parallel those observed for the accumulation of STH-2 mRNAs under similar conditions. This indicates that cis-acting elements necessary for the proper activation of the gene are present within 1 kb of 5′-flanking sequences. Functional analysis of 5′ deletions of the STH-2/GUS constructs by transient expression in leaf protoplasts revealed the presence of an upstream regulatory sequence between -135 and -52 which contains a TGAC motif, and a possible negative regulatory region between -52 and -28. A factor present in nuclear extracts of wounded potato tubers was found to bind specifically to nucleotides located between -135 to -105, suggesting that this region contains important cis-regulatory elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014935
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  • 9
    Electronic Resource
    Electronic Resource
    Treatment of Agrobacterium or leaf disks with 5-azacytidine increases transgene expression in tobacco (1993)
    Springer
    Plant molecular biology 21 (1993), S. 429-435 
    Details
    ISSN: 1573-5028
    Keywords: azacytidine ; DNA methylation ; gene expression ; inactivation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the effect of the demethylating agent azacytidine (azaC) on expression of a β-glucuronidase (GUS) gene transferred to tobacco leaf disks by Agrobacterium-mediated transformation. In a system where no selection was performed, where shoot formation was partially repressed, and where Agrobacterium does not express the GUS gene, we were able to follow the early events of transient and stable expression. Two days after inoculation, 8% of the cells expressed GUS but this proportion rapidly decreased to near zero in the following week. Treatment of leaf disks with azaC just after transformation retarded this inactivation to some extent, while treatment of Agrobacterium prior to transformation increased the frequency of transient expression. Three weeks after inoculation the number of GUS-expressing cells increased 4- to 6-fold in the leaf disks treated with azaC and in the leaf disks transformed with azaC-treated bacteria, while the control remained low. These data suggest that DNA methylation is involved in transgene inactivation and that a large number of silent but potentially active transgenes become integrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028801
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  • 10
    Electronic Resource
    Electronic Resource
    Transient and stable expression ofgusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1101-1127 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. TheGOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused togusA. ThegusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to theGOS2 constructs was found in stably transformed rice callus. ThegusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of theGOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028980
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  • 11
    Electronic Resource
    Electronic Resource
    Circadian and light-regulated expression of nitrate reductase in Arabidopsis (1993)
    Springer
    Plant molecular biology 23 (1993), S. 349-364 
    Details
    ISSN: 1573-5028
    Keywords: circadian regulation ; enzyme activity ; gene expression ; light regulation ; nitrate reductase ; phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of a number of plant genes is regulated by an endogenous circadian clock. We report that the Arabidopsis NIA2 (nitrate reductase) gene shows robust circadian oscillations in mRNA accumulation which persist for at least 5 days in plants that have been grown in a light-dark (LD) cycle and then transferred to continuous light (LL). We further show that NIA2 mRNA accumulation oscillates in a circadian fashion in plants that have been grown in LD and then transferred to continuous darkness (DD). Results from nuclear run-on transcriptional analysis suggest that the oscillations in steady-state levels of NIA2 mRNA abundance are not primarily due to changes in transcription but, instead, reflect post-transcriptional regulation. The circadian oscillations in NIA2 mRNA abundance are paralleled by circadian oscillations in nitrate reductase enzyme activity (NR activity) in Arabidopsis plants that have been grown in LD and then transferred either to DD or to LL. Etiolated Arabidopsis seedlings express neither NIA2 mRNA nor NR activity. However, both NIA2 mRNA accumulation and NR activity are induced by exposure to white light. The inductive effects of light on NIA2 mRNA accumulation are due, at least in part, to a very low fluence phytochrome-mediated response. However, the persistence of circadian oscillations in NIA2 mRNA abundance for at least 5 days in LL demonstrates that the circadian clock is capable of overriding or gating the inductive effects of light on NIA2 mRNA accumulation in Arabidopsis for an extended, continuous period of time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029010
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  • 12
    Electronic Resource
    Electronic Resource
    Coordinate gene expression of five subclass histones and the putative transcription factors, HBP-1a and HBP-1b, of histone genes in wheat (1993)
    Springer
    Plant molecular biology 23 (1993), S. 429-434 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; germination ; transcription factor ; wheat histone gene ; wheat seedling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of genes encoding five histones (H1, H2A, H2B, H3 and H4) and the putative transcription factors HBP-1a (17) and HBP-1b (c38) was examined during early germination and in various tissues of young wheat seedlings. The steady-state levels of core histone (H2A, H2B, H3 and H4) mRNAs were coordinately cell cycle-dependent and paralleled the rate of DNA synthesis during early germination, whereas the expression pattern of the linker histone (H1) genes differed. The five subclass histone genes were actively expressed in the meristematic tissues of young seedlings. Moreover, H1 genes were expressed in leaves that consist mostly of non-proliferating cells, in which core histone genes showed little expression. Quantitative alterations to the mRNAs of the putative transcription factors HBP-1a (17) and HBP-1b (c38) of wheat histone genes were similar to those of the core histone mRNAs, suggesting that both factors function in the cell cycle-dependent expression of wheat core histone genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029019
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  • 13
    Electronic Resource
    Electronic Resource
    Transient and stable expression of gusA fusions with rice genes in rice, barley and perennial ryegrass (1993)
    Springer
    Plant molecular biology 23 (1993), S. 643-669 
    Details
    ISSN: 1573-5028
    Keywords: transformation ; promoters ; introns ; gene expression ; Oryza sativa ; Hordeum vulgare ; Lolium perenne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional and translational fusions were made between the reading frame coding for β-D-glucuronidase and sequences of either a constitutively expressed rice gene (GOS2) involved in initiation of translation or a light-inducible rice gene (GOS5). The transient expression of the fusions was studied via particle bombardment of seedling tissues of rice, perennial ryegrass and barley. Furthermore, the results of transient and stable expression were compared for cell suspensions of four rice varieties, one barley variety and one perennial ryegrass variety. The GOS2-gusA fusions were active in all three monocots studied. Best results were obtained for a construct having both a transcriptional and a translational fusion as well as intron and exon sequences (PORCEHyg). The level of GUS activity was in the range of activities as obtained by the 35S CaMV promoter transcriptionally fused to gusA. The gusA fusion with the light-inducible gene (GOS5) was active in green seedling tissues of all monocots studied. Also a weak expression compared to the GOS2 constructs was found in stably transformed rice callus. The gusA fusions with the mannopine synthase promoters 1′ and 2′ of the TR-DNA were transiently expressed at lower levels in cell suspensions than PORCEHyg. For stably transformed rice callus the expression of the GOS2-gusA fusion often decreased during prolonged subculture. This decrease in GUS activity and the various GUS-staining phenotypes of transgenic calli are explained by the presence of different cell types in the suspensions used and in the calli. It is presumed that the nature of the cells and their relative contribution in the calli change drastically upon further subculture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021522
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  • 14
    Electronic Resource
    Electronic Resource
    Molecular analysis and spatial expression pattern of a low-temperature-specific barley gene, blt101 (1993)
    Springer
    Plant molecular biology 23 (1993), S. 871-879 
    Details
    ISSN: 1573-5028
    Keywords: cold ; low temperature ; barley ; gene expression ; cDNA ; shoot meristem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone of the previously unreported low-temperature-induced gene blt101 was isolated after a differential screen of a cDNA library prepared from low-temperature (6 °C day/2 °C night) grown barley shoot meristems. Southern blot analysis of barley ditelosomic addition lines was used to assign this single-copy gene to the long arm of chromosome 4. Analysis of steady-state levels of blt101 mRNA showed the induction of this transcript in shoot meristems upon transfer of barley (cv. Igri) plants from control (20 °C/15 °C) to low (6 °C/2 °C) temperature treatment. Further, the high level of this transcript is maintained at low temperatures but is reduced on transfer from low to control temperatures. The gene is not induced by drought or by foliar application of ABA. Analysis of segregating doubled haploid lines shows that there is no specific association of this gene with either spring/winter growth habit or frost hardiness. Examination of the spatial expression pattern revealed ubiquitous expression of blt101 in low-temperature (6 °C/2 °C) grown barley shoot meristems, mature leaves and roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021541
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  • 15
    Electronic Resource
    Electronic Resource
    Differential, temporal and spatial expression of genes involved in storage oil and oleosin accumulation in developing rapeseed embryos: implications for the role of oleosins and the mechanisms of oil-body formation (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1015-1027 
    Details
    ISSN: 1573-5028
    Keywords: embryos ; gene expression ; oleosin ; rapeseed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The temporal and spatial expression of oleosin and Δ9-stearoyl-ACP desaturase genes and their products has been examined in developing embryos of rapeseed, Brassica napus L. var. Topas. Expression of oleosin and stearate desaturase genes was measured by in situ hybridisation at five different stages of development ranging from the torpedo stage to a mature-desiccating embryo. The temporal pattern of gene expression varied dramatically between the two classes of gene. Stearate desaturase gene expression was relatively high, even at the torpedo stage, whereas oleosin gene expression was barely detectable at this stage. By the stage of maximum embryo fresh weight, stearate desaturase gene expression had declined considerably while oleosin gene expression was at its height. In contrast to their differential temporal expression, the in situ labelling of both classes of embryo-specific gene showed similar, relatively uniform patterns of spatial expression throughout the embryo sections. Immunogold labelling of ultra-thin sections from radicle tissue with anti-oleosin antibodies showed similar patterns to sections from cotyledon tissue. However, whereas at least three oleosin isoforms were detectable on western blots of homogenates from cotyledons, only one isoform was found in radicles. This suggests that some of the oleosin isoforms may be expressed differentially in the various types of embryo tissue. The differential timing of stearate desaturase and oleosin gene expression was mirrored by similar differences in the timing of the accumulation of their ultimate products, i.e. storage oil and oleosin proteins. Oil-body fractions prepared from young (2.5 mg) embryos contained very little oleosin protein, as examined by SDS-PAGE and western blotting, whereas identically prepared fractions from dry seeds contained over 10% (w/w) oleosin. Dehydration of oil bodies from young embryos resulted in their breakdown and coalescence into large clumps of oil which could not be re-emulsified, even after rehydration. In contrast, the oleosin-rich oil bodies from mature embryos were stable to dehydration and subsequent rehydration. It is suggested that, in developing rapeseed embryos, the accumulation of storage oil and oleosins is not concomitant but that the eventual deposition of oleosins onto the surfaces of storage oil bodies is essential for their stability during seed desiccation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021816
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  • 16
    Electronic Resource
    Electronic Resource
    Isolation and characterization of pollen-specific maize genes with sequence homology to ragweed allergens and pectate lyases (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1061-1065 
    Details
    ISSN: 1573-5028
    Keywords: allergens ; gene expression ; microsporogenesis ; pectate lyase ; pollen ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone (Zm58.1) was isolated by differential screening from a cDNA library made to mature Zea mays pollen, and shown to be pollen-specific by RNA blot analysis. When this partial-length clone was used to probe a genomic library, a similar but distinct pollen-specific genomic clone (68% sequence identity) was isolated (Zm58.2). The putative proteins coded for by these two clones show sequence homology to several flower-expressed gene products from various plant species, including known pollen allergens from short ragweed (Ambrosia artemisiifolia), and to pectate lyases from the plant pathogenic bacteria Erwinia spp. The two genes map to different chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021820
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  • 17
    Electronic Resource
    Electronic Resource
    A novel blue light- and abscisic acid-inducible gene of Arabidopsis thaliana encoding an intrinsic membrane protein (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1187-1198 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; blue light ; floral induction ; gene expression ; membrane protein ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Continuous irradiation with blue light (400–500 nm) induces flower formation in plantlets of Arabidopsis thaliana (C24) while red light (600–700 nm) is ineffective. This observation started a search for genes that are activated by blue light and initiate the morphogenic programme leading to flower formation. Several genes were identified via their cDNAs. From these clone AthH2, with an open reading frame for a hydrophobic 30.5 kDa polypeptide, was selected for further characterization of the corresponding gene. From a genomic library a DNA fragment of about 6.4 kb was isolated, comprising the coding region as well as 5′-upstream and 3′-downstream flanking segments. The coding region is composed of four exons, which specify a polypeptide of 286 amino acids. Several potential regulatory elements were found between position −670 and −1140 including GA and ABA sequence motifs. The latter could account for the observed induction of the AthH2 gene by ABA. Southern blot analysis of Arabidopsis genomic DNA suggests that the AthH2 gene is encoded by a single-copy gene. Hydropathy plots and secondary structure analysis of the putative polypeptide predict six membrane-spanning domains implicating a function as transmembrane channel protein. It displays significant homology with the proteins TR7a of pea (82%) and RD 28 of A. thaliana (68%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042352
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  • 18
    Electronic Resource
    Electronic Resource
    Different expression of calpain in skeletal muscle of Japanese quail (Coturnix coturnix japonica) lines selected for body weight (1993)
    Springer
    Biochemical genetics 31 (1993), S. 485-495 
    Details
    ISSN: 1573-4927
    Keywords: muscle protein degradation ; calpain ; gene expression ; genetic variation ; Japanese quail
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Calpain activity was determined by western blot analysis of steady-state concentrations ofm-calpain (calpain requiring millimolar Ca2 for activation) and also by northern blot analysis of steady-state concentrations of mRNA encodingm-calpain in three lines of quail: a random-bred control line (RR) and two lines selected for body weight, one for increased body weight (LL) and another for decreased body weight (SS). Them-calpain activities in skeletal muscle were higher in the SS line and lower in the LL line. From western blot analysis, enzyme levels of calpain were almost the same for all three lines. At the level of gene expression, the mRNA concentration encodingm-calpain was higher in the LL and lower in the SS line. These results suggest that the regulation of calpain activity in skeletal muscle is a three-step process, regulation at the transcription level, regulation at the enzyme level, and regulation of the activation of calpain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00554075
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  • 19
    Electronic Resource
    Electronic Resource
    Molecular cloning and characterization of a legumin-like storage protein cDNA of Douglas fir seeds (1993)
    Springer
    Plant molecular biology 21 (1993), S. 709-715 
    Details
    ISSN: 1573-5028
    Keywords: cDNAs ; seed storage proteins ; Pseudotsuga menziesii ; gene expression ; nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA library was made from poly(A)+ RNA isolated from developing Douglas fir (Pseudotsuga menziesii) embryo and megagametophytic tissue, and the cDNA clones were identified by immunoscreening with polyclonal antiserum against the crystalloid storage protein complex of Douglas fir. The nucleotide sequence of the longest cDNA insert (DF1) was analysed. The amino acid sequence derived from the DNA sequence verified its identity as a legumin-like storage protein (pseudotsugin) and confirmed that the protein is synthesized as a precursor similar to the 11–12S storage globulins. The transcripts corresponding to cDNA insert DF1 were abundant in the early-to mid-stages of embryogenesis in the diploid embryonic axes as well as in the haploid megagametophytic tissue. The deduced amino acid sequence of pseudotsugin consists of a 29 amino acid N-terminal signal peptide preceding the acidic polypeptide region (286 amino acids) and the subsequent basic polypeptide region (212 amino acids). The site for post-transcriptional cleavage of the precursor polypeptide to make the A and B polypeptides is localized between asparagine −315 and glycine −316 and is highly conserved between angiosperms and gymnosperms. The deduced amino acid sequence for the DF1 cDNA clone reveals that pseudotsugin is rich in arginine, glutamic acid and serine and is low in cysteine, methionine and lysine. Comparison of the deduced amino acid sequence of Douglas fir pseudotsugin shows between 29–38.5% identity with angiosperm species, 63% identity with interior spruce, and 60% identity with eastern white pine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014555
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  • 20
    Electronic Resource
    Electronic Resource
    Cis-acting regulatory regions of the soybean seed storage 11S globulin gene and their interactions with seed embryo factors (1993)
    Springer
    Plant molecular biology 21 (1993), S. 973-984 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; Glycine max ; protein-DNA interaction ; seed storage protein gene ; transcriptional regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 2.2 kb fragment containing the 5′-flanking region of the soybean glycinin A2B1a gene and its successive deletions with a shorter 5′-flanking sequence were fused, in frame, to the β-glucuronidase (GUS) reporter gene. The resultant fusions were introduced into tobacco plants via Agrobacterium tumefaciens. Assays of the GUS activity in seeds of transgenic tobacco showed that the upstream region, −657 to −327 (relative to the transcription initiation site [+1]), of the glycinin gene is required for optimal expression of the transformed gene. Interactions between embryo nuclear factors and DNA fragments covering the downstream region of −326, in which are included the TATA box and legumin boxes, were not apparent. The embryo factors capable of binding specifically to three subregions, −653 to −527, −526 to −422, and −427 to −321, of the upstream regulatory region were detected. Such factors appeared to be organ-specific and could be found solely in developing seeds at the early middle stage of embryogenesis (around 24 days after flowering). Evidence obtained by characterizing the nature of the binding proteins and by gel mobility shift assays established that the same factor does interact with a consensus motif 5′-ATA/TATTTCN-/CTA-3′ which occurs four times in the cis-acting regulatory region between −657 and −327. Moreover, this conserved motif could also be found in the 5′ regulatory region of another glycinin A1aB1b gene. Thus it is likely that the observed interaction between the nuclear factor and the conserved motifs would lead to activation of transcription from the glycinin genes in maturing soybean seeds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023596
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  • 21
    Electronic Resource
    Electronic Resource
    Expression of the Arabidopsis AtAux2-11 auxin-responsive gene in transgenic plants (1993)
    Springer
    Plant molecular biology 22 (1993), S. 731-749 
    Details
    ISSN: 1573-5028
    Keywords: auxin ; localization ; gene expression ; beta-galactosidase ; Arabidopsis ; auxin-inducible promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five constructions containing deletions of the promoter from an auxin-inducible gene of Arabidopsis thaliana, AtAux2-11, were fused to the coding region of the reporter gene LacZ, which encodes β-galactosidase, and a polyadenylation 3′-untranslated nopaline synthase sequence from Agrobacterium. These chimeric genes were introduced into Arabidopsis by Agrobacterium tumefaciens-mediated transformation, and expression of the gene was examined by spectrophotometric and histochemical analyses. A 600 bp fragment from the AtAux2-11 promoter conferred histochemical patterns of staining similar to the longest 5′ promoter tested, a 3.0 kb fragment. Localization of AtAux2-11/LacZ activity in the transgenic plants revealed spatial and temporal expression patterns that correlated with tissues and cells undergoing physiological processes modulated by auxin. LacZ activity was expressed in the elongating region of roots, etiolated hypocotyls, and anther filaments. Expression was detected in the vascular cylinder of the root and the vascular tissue, epidermis, and cortex of the hypocotyl, and filament. The AtAux2-11/LacZ gene was preferentially expressed in cells on the elongating side of hypocotyls undergoing gravitropic curvature. Expression of the chimeric gene in the hypocotyls of light-grown seedlings was less than that in etiolated seedling hypcotyls. The AtAux2-11/LacZ gene was active in the root cap, and expression in the root stele increased at sites of lateral root initiation. Staining was evident in cell types that develop lignified cell walls, e.g. trichomes, anther endothecial cells, and especially developing xylem. The chimeric gene was not expressed in primary meristems. While the magnitude of expression increased after application of exogenous auxin (2,4-D), the histochemical localization of AtAux2-11/LacZ remained unchanged. Transgenic plants with a 600 bp promoter construct (−0.6 kb AtAux2-11/LacZ) had higher levels of basal and auxin-inducible expression than plants with a 3.0 kb promoter construct. Transgenic plants with a −500 bp promoter had levels of expression similar to the −3.0 kb construct. The −0.6 kb AtAux2-11/LacZ gene responded maximally to a concentration of 5 × 10−6 to 5 × 10−5 M 2,4-D and was responsive to as little as 5 × 10−8 M. The evidence presented here suggests that this gene may play a role in several auxin-mediated developmental and physiological processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027361
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  • 22
    Electronic Resource
    Electronic Resource
    Down-regulation of two non-homologous endogenous tomato genes with a single chimaeric sense gene construct (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1-9 
    Details
    ISSN: 1573-5028
    Keywords: down-regulation ; gene expression ; polygalacturonase ; pectinesterase ; chimaeric sense gene ; transgenic ; co-suppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tomatoes (Lycopersicon esculentum Mill cv. Ailsa Craig) were transformed with a gene construct having 244 bp of the 5′ end of a polygalacturonase (PG) cDNA, coding for a 71 amino acid N-terminal extension to the mature protein, fused to 1320 bp of a pectinesterase (PE) cDNA encoding the full sequence of the mature PE protein. This chimaeric gene was inserted in a sense orientation between a CaMV 35S promoter and terminator for constitutive expression. In transformed tomato plants expression of the endogenous PG and PE genes in the fruit was inhibited; there was little or no observable PG and PE mRNA and a substantial reduction in the level of PG and PE enzyme activity. The transgene was expressed in the leaves of the transformed plants as demonstrated by the accumulation of mRNA, but no protein product could be identified. However, no transgene mRNA or protein were observed in the transgenic fruit. This paper represents the first report of the down-regulation of two non-homologous endogenous genes using a single gene construct. A sense gene construct was responsible for these effects. These findings are discussed in relation to possible mechanisms of action of co-suppression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021414
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  • 23
    Electronic Resource
    Electronic Resource
    The resistance of cowpea seeds to bruchid beetles is not related to levels of cysteine proteinase inhibitors (1993)
    Springer
    Plant molecular biology 23 (1993), S. 215-219 
    Details
    ISSN: 1573-5028
    Keywords: cowpea ; cystatin ; cysteine endoproteinases ; gene expression ; insect resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA encoding a cysteine proteinase inhibitor was isolated from a cDNA library prepared from developing seeds of an insect-resistant line of cowpea. The sequence of the encoded protein was homologous with those of other plant cysteine endoproteinase inhibitors, and with Type 2 cystatins from animals. Southern blot analyses indicated that small gene families were present in both resistant and susceptible lines of cowpea, while northern blot analyses showed similar levels of expression. It is concluded that the levels of expression of the inhibitor do not account for the differences in insect resistance of the two lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021433
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  • 24
    Electronic Resource
    Electronic Resource
    cDNA cloning and characterisation of novel ripening-related mRNAs with altered patterns of accumulation in the ripening inhibitor (rin) tomato ripening mutant (1993)
    Springer
    Plant molecular biology 23 (1993), S. 193-207 
    Details
    ISSN: 1573-5028
    Keywords: dehydrogenase ; ethylene ; fruit ; gene expression ; UDP glucuronosyl/glucosyl transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA library produced from mRNA isolated from the pericarp of wild-type tomato fruit (Lycopersicon esculentum Mill. cv Ailsa Craig) at the first visible sign of fruit ripening was differentially screened to identify clones whose homologous mRNAs were present at reduced levels in fruit of the tomato ripening mutant, ripening inhibitor,rin. Five clones were isolated (pERT 1, 10, 13, 14, 15). Accumulation of mRNA homologous to each of these clones increased during the ripening of wild-type fruit and showed reduced accumulation in ripening rin fruit. The levels of three of them (homologous to ERT 1, 13 and 14) were increased by ethylene treatment of the mutant fruit. A further clone, ERT 16 was identified for a mRNA present at a high level in both normal and mutant fruit at early stages of ripening. Database searches revealed no significant homology to the DNA sequence of ERT 14 and 15; however, DNA and derived amino acid sequence of ERT 1 both contain regions of homology with several reported UDP-glucosyl and glucuronosyl transferases (UDPGT) and with a conserved UDPGT motif. A derived amino acid sequence from the ERT 10 cDNA contains a perfect match to a consensus sequence present in a number of dehydrogenases. The ERT 13 DNA sequence has homology with an mRNA present during potato tuberisation. The presence of these mRNAs in tomato fruit is unreported and their role in ripening is unknown. The ERT 16 DNA sequence has homology with a ripening/stress-related cDNA isolated from tomato fruit pericarp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021431
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  • 25
    Electronic Resource
    Electronic Resource
    A histidine decarboxylase-like mRNA is involved in tomato fruit ripening (1993)
    Springer
    Plant molecular biology 23 (1993), S. 627-631 
    Details
    ISSN: 1573-5028
    Keywords: ethylene ; histamine ; gene expression ; Lycopersicon esculentum ; ripening mutant ; ripening inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA sequencing of a tomato ripening-related cDNA, TOM 92, revealed an open reading frame with homology to several pyridoxal 5′-phosphate histidine decarboxylases, containing the conserved amino acid residues known to bind pyridoxal phosphate and α-fluoromethylhistidine, an inhibitor of enzyme activity. TOM 92 mRNA accumulated during early fruit ripening and then declined. Fruit of the ripeningimpaired tomato mutant, ripening inhibitor (rin), did not accumulate TOM 92 mRNA, and its accumulation was not restored by treatment of fruit with ethylene. The TOM 92 mRNA was not detected in tomato leaves and unripe fruit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019310
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  • 26
    Electronic Resource
    Electronic Resource
    Cell-type specific expression of three rice genes GOS2, GOS5 and GOS9 (1993)
    Springer
    Plant molecular biology 23 (1993), S. 889-894 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; in situ hybridization ; photosystem I subunit ; rice ; suil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cell-type-specific expression of three rice genes, GOS2, GOS5 and GOS9, was studied by mRNA in situ hybridization. Previous northern blot analysis revealed that these genes were constitutive, green tissue-specific and root-specific, respectively. In this study, GOS2 transcripts were observed in all leaf cell types. In roots, a temporal and spatial expression pattern was noticed. Higher mRNA levels were observed in lateral roots, especially in parenchymal cells of the vascular cylinder. Expression of GOS5 was mainly found in chloroplast-containing cells. For GOS9, significant levels of signal were observed in root and leaf sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021543
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  • 27
    Electronic Resource
    Electronic Resource
    Transcription of mononucleosomal particles acetylated in the presence of n-butyrate (1993)
    Springer
    Molecular biology reports 18 (1993), S. 37-41 
    Details
    ISSN: 1573-4978
    Keywords: gene expression ; histone acetylation ; mononucleosomal particles ; RNA polymerase II ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although a correlation between chemical acetylation of the amino-terminal tails of core histones and stimulation of RNA synthesis has been reported for nucleosomal core particles (Piñeiro et al. (1991) Biochem. Biophys. Res. Commun. 177: 370), no differences in transcription are detected between acetylated and nonacetylated mononucleosomal particles obtained from HeLa cells in the presence and absence of n-butyrate. Apparently, the lysine residues modified in the presence of n-butyrate are not the same responsible for the observed acetylation-induced transcription. The acetylation obtained with n-butyrate might be significantly different from that present in transcriptionally active chromatin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01006893
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  • 28
    Electronic Resource
    Electronic Resource
    Jasmonic acid-inducible gene expression of a Kunitz-type proteinase inhibitor in potato tuber disks (1993)
    Springer
    Plant molecular biology 21 (1993), S. 539-541 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; jasmonic acid ; Kunitz-type proteinase inhibitor ; patatin ; potato (Solanum tuberosum L.) ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Messenger RNAs of a potato (Solanum tuberosum L.) Kunitz-type proteinase inhibitor(s) (PKPI) were present in potato disks excised from tubers stored for 14 months (old tubers) or 2 months (young tubers) after harvest, and disappeared during the aseptic culture. The PKPI mRNA accumulation was found to be induced in potato disks from the old tubers by the addition of jasmonic acid (JA) [3-oxo-2-(2′-cis-pentenyl)-cyclopentane-1-acetic acid].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028810
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  • 29
    Electronic Resource
    Electronic Resource
    Structure and expression of the S locus-related genes of maize (1993)
    Springer
    Plant molecular biology 21 (1993), S. 1171-1174 
    Details
    ISSN: 1573-5028
    Keywords: transmembrane receptor ; protein kinase ; self-incompatibility ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The extracellular of the putative receptor-like protein kinase, ZmPK1, is related to the self-incompatibility locus (S-locus) genes of Brassica. We have isolated and characterized a genomic DNA clone of ZmPK1 and three additional genes from maize that are highly related to ZmPK1. These three S-locus related genes do not appear to have the protein kinase catalytic domain that is found in ZmPK1. One or more of these genes are expressed specifically in the silks. This initial description of S-locus related genes in monocotyledonous plants suggests that the S-locus domain may be involved in several different cellular functions in a wide variety of plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023612
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  • 30
    Electronic Resource
    Electronic Resource
    Calmodulin isoforms in Arabidopsis encoded by multiple divergent mRNAs (1993)
    Springer
    Plant molecular biology 22 (1993), S. 215-225 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis ; calmodulin sequence ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three new, unique cDNA sequences encoding isoforms of calmodulin (CaM) were isolated from an Arabidopsis cDNA library cloned in λgt10. These sequences (ACaM-4, -5, and -6) represent members of the Arabidopsis CaM gene family distinct from the three DNA sequences previously reported. ACaM-4 and -6 encode full-length copies of CaM mRNAs of ca. 0.75 kb. The ACaM-5 sequence encodes a partial length copy of CaM mRNA that is lacking sequences encoding the amino-terminal 10 amino acids of mature CaM and the initiator methionine. The derived amino acid sequence of ACaM-5 is identical to the sequences encoded by two of the previously characterized ACaM cDNAs, and is identical to TCH-1 mRNA, whose accumulation was increased by touch stimulation. The polypeptides encoded by ACaM-4 and -6 differ from that encoded by ACaM-5 by six and two amino acid substititions, respectively. Most of the deduced amino acid sequence substitutions in the Arabidopsis CaM isoforms occurred in the fourth Ca2+-binding domain. Polymerase chain reaction amplification assays of ACaM-4, -5 and -6 mRNA sequences indicated that each accumulated in Arabidopsis leaf RNA fractions, but only ACaM-4 and -5 mRNAs were detected in silique total RNA. The six different CaM cDNA sequences each hybridize with unique Eco RI restriction fragments in genomic Southern blots of Arabidopsis DNA, indicating that these sequences were derived from distinct structural genes. Our results suggest that CaM isoforms in Arabidopsis may have evolved to optimize the interaction of this Ca2+-receptor protein with specific subsets of response elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014930
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  • 31
    Electronic Resource
    Electronic Resource
    An Arabidopsis gene with homology to glutathione S-transferases is regulated by ethylene (1993)
    Springer
    Plant molecular biology 22 (1993), S. 517-523 
    Details
    ISSN: 1573-5028
    Keywords: ethylene ; gene expression ; Arabidopsis thaliana ; glutathione S-transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone obtained from Arabidopsis leaf RNA encodes a 24 kDa protein with homology to glutathione S-transferases (GST). It is most homologous with a tobacco GST (57% identity). In Arabidopsis, expression of GST mRNA is regulated by ethylene. Exposure of plants to ethylene increased the abundance of GST mRNA, while treatment with norbornadiene had the reverse effect. Ethylene had no effect on the mRNA level in ethylene-insensitive etr1 plants. The abundance of this mRNA increased with the age of plants. DNA hybridizations indicate that GSTs are encoded by a large multigene family in Arabidopsis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015980
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  • 32
    Electronic Resource
    Electronic Resource
    Upstream regulatory sequences from two β-conglycinin genes (1993)
    Springer
    Plant molecular biology 22 (1993), S. 873-885 
    Details
    ISSN: 1573-5028
    Keywords: β-conglycinin ; gene expression ; legumin box ; seed storage protein ; vicilin box
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genes encoding the β-conglycinin seed storage proteins of soybean are expressed only in seeds during specific stages of development. The different subunits of β-conglycinin, α′, α and β, are encoded by distinct members of a gene family. Yet there are marked differences in the regulation of the genes encoding the α′/α and β subunits. Previous work (Chen et al., EMBO J 7: 297–302, 1988) identified a seed specific transcriptional enhancer upstream of a gene encoding the α′ subunit. Mutations were made within this region to discern its functional components. Among those identified is a 62 bp region (between −77 and −140) that contains a vicilin box consensus sequence as well as a sequence that binds the soybean nuclear factor SEF4 in vitro. A second region, which contains a sequence homologous to the core of the legumin box consensus (i.e., CATGCAT-like or RY repeat element) at −246, was also shown to affect the activity of this enhancer in transgenic plants. A series of 5′ terminal deletions were used to identify regulatory elements upstream of the β subunit gene. Two regions were identified (from −553 to −442 and from −308 to −72) that, when deleted, led to a marked reduction in gene expression. Both of these elements contain sequences that bind SEF4 in vitro. The distal element also contains an AT-rich segment that recognizes a second nuclear factor, SEF1, in vitro. Neither of these elements contains any homology to the vicilin box consensus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027372
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  • 33
    Electronic Resource
    Electronic Resource
    Molecular characterization of four chitinase cDNAs obtained fromCladosporium fulvum-infected tomato (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1017-1029 
    Details
    ISSN: 1573-5028
    Keywords: chitinase ; gene expression ; pathogenesis-related protein ; plant-fungus interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Complementary DNA clones encoding acidic and basic isoforms of tomato chitinases were isolated fromCladosporium fulvum-infected leaves. The clones were sequenced and found to encode the 30 kDa basic intracellular and the 26 and 27 kDa acidic extracellular tomato chitinases previously purified (M.H.A.J. Joostenet al., in preparation). A fourth truncated cDNA which appears to encode an extracellular chitinase with 82% amino acid similarity to the 30 kDa intracellular chitinase was also isolated. Characterization of the clones revealed that the 30 kDa basic intracellular protein is a class I chitinase and that the 26 and 27 kDa acidic extracellular proteins which have 85% peptide sequence similarity are class II chitinases. The characterized cDNA clones represent four from a family of at least six tomato chitinases. Southern blot analysis indicated that, with the exception of the 30 kDa basic intracellular chitinase, the tomato chitinases are encoded by one or two genes. Northern blot analysis showed that the mRNA encoding the 26 kDa acidic extracellular chitinase is induced more rapidly during an incompatibleC. fulvum-tomato interaction than during a compatible interaction. This difference in timing of mRNA induction was not observed for the 30 kDa basic intracellular chitinase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028974
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  • 34
    Electronic Resource
    Electronic Resource
    Structure and expression of a nuclear gene for the PSI-D subunit of photosystem I inNicotiana sylvestris (1993)
    Springer
    Plant molecular biology 22 (1993), S. 985-994 
    Details
    ISSN: 1573-5028
    Keywords: ferredoxin-binding subunit ; gene expression ; gene structure ; Nicotiana sylvestris ; photosystem I ; psaD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The PSI-D subunit is the ferredoxin-binding site of photosystem I, and is encoded by the nuclear genepsaD. We isolated apsaD genomic clone fromNicotiana sylvestris, by screening a genomic library with apsaD cDNA which we previously cloned fromN. sylvestris (Yamamotoet al., Plant Mol Biol 17: 1251, 1991). Nucleotide sequence analysis revealed that this genomic clone contains apsaD gene, which does not correspond to thepsaD cDNA, so we designated these genespsaDb andpsaDa, respectively. ThepsaDb clone encodes a protein of 214 amino acids uninterrupted by introns. The N-terminal sequence determined for theN. sylvestris PSI-D protein encoded bypsaDb begins at the 49th residue. The products ofpsaDa andpsaDb share 82.7% and 79.5% identity at the amino acid and nucleotide levels, respectively. Genomic Southern analysis showed that two copies ofpsaD are present in theN. sylvestris genome. Ribonuclease protection assays and immunoblot analysis inN. sylvestris indicate that both genes are expressed in leaves, stems and flower buds, but neither is expressed in roots. During leaf development, the ratio ofpsaDb topsaDa mRNA increases from 0.12 in leaf buds to 0.36 in mature leaves. The relative abundance of the corresponding proteins decreased over the same developmental period. These results indicate that differential regulation mechanisms controlpsaDa andpsaDb expression at both the mRNA and protein levels during leaf development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028971
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  • 35
    Electronic Resource
    Electronic Resource
    Fruit developmental regulation of the kiwifruit actinidin promoter is conserved in transgenic petunia plants (1993)
    Springer
    Plant molecular biology 23 (1993), S. 489-499 
    Details
    ISSN: 1573-5028
    Keywords: kiwifruit ; actinidin ; protease activity ; GUS fusion ; gene expression ; fruit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have examined the expression of actinidin, a cysteine protease found in kiwifruit, over the course of fruit development. Protease activity was first seen in fruit that had reached about half their final weight, and rose to high levels at harvest. The 5′-flanking region (nucleotides −1301 to +58) of a kiwifruit actinidin gene was fused to the β-glucuronidase (GUS)-coding region, and the chimaeric gene was introduced into transgenic petunia plants. Induction of the GUS gene was observed during the later stages of seed pod development, closely resembling the pattern of actinidin induction in fruit tissues of kiwifruit. Some GUS expression was also detected in the vascular system of the receptacle, leaves, stems and roots. A shorter promoter fragment consisting of nucleotides −115 to +58 conferred similar spatial and temporal regulation in some of the transgenic plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019297
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  • 36
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    Electronic Resource
    Molecular characterization of maize extensin expression (1993)
    Springer
    Plant molecular biology 23 (1993), S. 685-695 
    Details
    ISSN: 1573-5028
    Keywords: extensin ; gene expression ; hydroxyproline ; maize ; silk ; vegetative tissues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study concerned the developmental regulation of wall-localized, hydroxyproline-containing proteins in maize tissues and organs. Silk and pericarp cell walls contained more peptidyl hydroxyproline than did walls of any vegetative tissue, although all tissues and organs accumulated these proteins as they matured. In many tissues, hydroxyproline-rich proteins are first associated with the wall in a soluble form before being insolubilized through covalent attachment to the matrix. Because hydroxyproline was more soluble earlier than later in development, it appears that insolubilization was occurring in maize tissues and organs as well. Tissue prints reacted with an anti-extensin antibody gave positive results, indicating the presence of a soluble form of this common hydroxyproline-rich glycoprotein (HRGP). Silk and pericarp cells actively synthesized this extensin from abundant transcripts. In vegetative tissues, extensin transcripts were somewhat more abundant in seedlings than in pre-anthesis or mature plants, but levels were much lower than in silk and pericarp. Southern blots of maize genomic DNA indicated that these extensin transcripts are encoded by a small multigene family. Potential roles for extensin in reproductive/protective tissues versus the embryo or vegetative tissues are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021524
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  • 37
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    Metabolic regulation of α-amylase gene expression in transgenic cell cultures of rice (Oryza sativa L.) (1993)
    Springer
    Plant molecular biology 23 (1993), S. 737-747 
    Details
    ISSN: 1573-5028
    Keywords: α-amylase ; transgenic cell culture ; gene expression ; metabolic regulation ; Oryza sativa ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of two genes in the α-amylase gene family is controlled by metabolic regulation in rice cultured cells. The levels of RAmy3D and RAmy3E mRNAs in rice cultured cells are inversely related to the concentration of sugar in the culture medium. Other genes in the rice α-amylase gene family have little or no expression in cultured cells; these expression levels are not controlled by metabolic regulation. A RAmy3D promoter/GUS gene fusion was metabolically regulated in the transgenic rice cell line 3DG, just as the endogenous RAmy3D gene is regulated. An assay of GUS enzyme activity in 3DG cells demonstrated that RAmy3D/GUS expression is repressed when sugar is present in the culture medium and induced when sugar is removed from the medium. The 942 bp fragment of the RAmy3D promoter that was linked to the coding region of the GUS reporter gene thus contains all of the regulatory sequences necessary for metabolic regulation of the gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021529
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  • 38
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    Expression of thelacZ gene targeted to the HPRT locus in embryonic stem cells and their derivatives (1993)
    Springer
    Transgenic research 2 (1993), S. 1-13 
    Details
    ISSN: 1573-9368
    Keywords: gene expression ; lacZ ; HPRT ; ES cells ; gene targeting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenes in mice often exhibit different expression patterns in different transgenic lines. While the basis for this phenomenon is not understood, it is widely believed that the site at which the transgene becomes integrated into the mouse genome is a major factor in determining the pattern of expression. Most transgenic mice have been produced by microinjection of DNA into the male pronucleus, which results in integration of tandem arrays of the transgene at random chromosomal sites. In the experiments described in this report, electroporation of embryonic stem (ES) cells was used to place single copies of alacZ transgene into either random sites or into the HPRT (hypoxanthine phosphoribosyl transferase) locus of the mouse genome. Expression oflacZ was assayed by histochemical staining forEscherichia coli β-galactosidase activity in ES cells and in differentiated derivatives obtained by teratocarcinoma formation. Several of the randomly integrated cell lines expressedlacZ at high levels in a variety of cell types present in the tumours, but most notably in epithelial cells. Targeted cell lines withlacZ in opposite orientation to the direction of HPRT gene transcription also expressed well in epithelial cells, but the targeted cell lines did not express in a wider variety of cell types than some of the nontargeted cell lines. Targeted cell lines transcribinglacZ in the same orientation as HPRT transcription did not express high levels oflacZ in any differentiated cell type. Analysis of transcripts suggested that this orientation effect may have been the result of transcriptional interference perpetrated by the HPRT gene promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01977675
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  • 39
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    Electronic Resource
    Different expression of calpain in skeletal muscle of Japanese quail (Coturnix coturnix japonica) lines selected for body weight (1993)
    Springer
    Biochemical genetics 31 (1993), S. 485-495 
    Details
    ISSN: 1573-4927
    Keywords: muscle protein degradation ; calpain ; gene expression ; genetic variation ; Japanese quail
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Calpain activity was determined by western blot analysis of steady-state concentrations ofm-calpain (calpain requiring millimolar Ca2 for activation) and also by northern blot analysis of steady-state concentrations of mRNA encodingm-calpain in three lines of quail: a random-bred control line (RR) and two lines selected for body weight, one for increased body weight (LL) and another for decreased body weight (SS). Them-calpain activities in skeletal muscle were higher in the SS line and lower in the LL line. From western blot analysis, enzyme levels of calpain were almost the same for all three lines. At the level of gene expression, the mRNA concentration encodingm-calpain was higher in the LL and lower in the SS line. These results suggest that the regulation of calpain activity in skeletal muscle is a three-step process, regulation at the transcription level, regulation at the enzyme level, and regulation of the activation of calpain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426880
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  • 40
    Electronic Resource
    Electronic Resource
    Molecular biological approaches to plant nutrition (1993)
    Springer
    Plant and soil 155-156 (1993), S. 21-31 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; sulphur-nutrition ; gene cloning ; gene expression ; regulation ; crop improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the last decade, understanding of ion transport has grown sufficiently to pose sensible questions about the molecular nature of the processes and their regulation. Techniques for identifying and cloning genes and for genetic transformation provide the means for answering these questions. Transport of ions across membranes is obviously a major aspect of mineral nutrition since it occurs during initial absorption, compartmentation and mobilisation of nutrients. Here, we will briefly review the types of transport protein involved and show how molecular biology and recombinant DNA technology have revealed something of their structure. Strategies used to identify the genes for transporters are discussed and reference is made to areas in which the availability of cloned genes will facilitate future studies. Mineral nutrition involves, however, more than membrane transport. The absorption rates of major nutrients are quite strictly regulated by biochemical factors which vary with the rate at which nutrients are used in growth. Nitrogen, sulphur and phosphate nutrition in micro-organisms are regulated by the interaction of various DNA-binding proteins with the promoter regions of genes for key enzymes in the assimilatory pathways and the specific ion permeases. The expression of the regulatory protein or its activity can be modified by metabolites, such as glutamine. Some evidence supports the idea that higher plants also have groups of genes with a common regulation of expression. An attempt is made to identify some reasonable objectives, which should increase understanding of the regulation of nutrient transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024981
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  • 41
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    Electronic Resource
    Developmental expression of glutathione-S-transferase in maize and its possible connection with herbicide tolerance (1993)
    Springer
    Euphytica 67 (1993), S. 221-230 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; glutathione-S-transferase ; glutathione ; herbicide tolerance ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Crop improvement for tolerance to specific herbicides is an important breeding target, since molecules performing well with regard to environmental safety are frequently not completely selective for crops. The glutathione (GSH)/glutathione-S-transferase (GST) system is a general mechanism of detoxification that in higher plants may confer tolerance to some herbicides. GSH level and GST activity were measured in different maize inbred lines, in the absence or in the presence of EPTC (a thiocarbamate) and of Alachlor (a chloroacetanilide); a wide genetic variability was observed for these parameters, which appear to be involved in plant tolerance to herbicides. Isozyme analysis was performed on roots, leaves, scutellum, pollen, coleoptile, mesocotyl of the same inbreds: it revealed the presence of many GST forms in maize, showing high polymorphism; they are controlled by at least five genes, the expression of which is developmentally regulated in the different tissues analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040624
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  • 42
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    Solanum phureja genes are expressed in the leaves and tubers of aneusomatic potato dihaploids (1993)
    Springer
    Euphytica 69 (1993), S. 1-6 
    Details
    ISSN: 1573-5060
    Keywords: gene expression ; isozymes ; patatin ; potato dihaploids ; Solanum phureja
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The expression of leaf isozymes and tuber patatin in dihaploids derived from the Solanum tuberosum cv. Pentland Crown was investigated. Seven of the dihaploids were aneusomatic containing additional chromosomes from the S. phureja dihaploid inducer. Of these, four genotypes expressed leaf isozymes characteristic of the S. phureja dihaploid inducer, and the tubers of three aneusomatic dihaploids contained a S. phureja form of patatin. Aneusomatic dihaploids in which the proportion of cells containing additional S. phureja chromosomes was relatively small (i.e. 1–15%) did not express leaf isozyme markers or patatin bands characteristic of the dihaploid inducer or showed only faint expression of one or two markers. However, those with a high proportion of cells containing additional chromosomes (50–55%) had a range of strongly expressed leaf isozymes that were characteristic of the dihaploid inducer and also expressed the S. phureja tuber patatin. One dihaploid genotype was exclusively euploid (2n〈24), yet is expressed a S. phureja leaf isozyme marker and S. phureja tuber patatin, suggesting recombination or chromosome substitution between the genome of the S. phureja dihaploid inducer and the cultivar Pentland Crown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021720
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  • 43
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    Redox control of gene expression and the function of chloroplast genomes — an hypothesis (1993)
    Springer
    Photosynthesis research 36 (1993), S. 95-102 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast genome ; electron transport ; evolution ; gene expression ; redox response regulators ; redox sensors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two-component regulatory systems that respond to changes in redox potential have recently been discovered in bacteria. ‘Redox sensors’ are defined as electron carriers which initiate control of gene expression upon oxidation or reduction. ‘Redox response regulators’ are defined as DNA-binding proteins which modify gene expression as a result of the action of redox sensors. Redox sensors and redox response regulators may comprise a mechanism for feedback control of redox potential in photosynthetic electron transport chains, thereby protecting plants, algae and photosynthetic bacteria from damage caused by electrochemistry operating on inappropriate electron donors and acceptors. Chloroplast redox sensors and redox response regulators, themselves encoded in the nucleus, may place chloroplast gene expression under redox regulatory control. This may account for the persistence, in evolution, of chloroplast genomes, and for the constancy of the sub-set of chloroplast proteins encoded and synthesised in situ. These and other predictions are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016274
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  • 44
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    Molecular approaches to the study of evolution and phylogeny of the Nemertina (1993)
    Springer
    Hydrobiologia 266 (1993), S. 255-265 
    Details
    ISSN: 1573-5117
    Keywords: gene expression ; nucleotide sequence ; invertebrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular biological tools currently available to us are revolutionizing the way in which we can address questions in evolutionary biology. The purpose of this article is to provide an overview of molecular techniques and applications available to biologists who are interested in evolutionary studies but who have little acquaintance with molecular biology. In evolutionary biology, techniques designed to determine degree of nucleic acid similarity are in common use and will be dealt with first. Another approach, namely gene expression studies, has strong implications for evolutionary biology but generally requires substantial familiarity with molecular biological tools. Expression studies provide powerful tools for discerning processes of speciation, as in the selection of genetic variants, as well as discerning lineages, e.g., expression of specific homeobox genes during segment formation. For investigations where either nucleic acid identity or gene expression are the ultimate goal, detailed information, protocols and appropriate controls are beyond the scope of this work but, where possible, recent review articles are cited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00013373
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  • 45
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    Electronic Resource
    Cyclic AMP regulation of the human choline acetyltransferase gene (1993)
    Springer
    Neurochemical research 18 (1993), S. 271-275 
    Details
    ISSN: 1573-6903
    Keywords: Choline acetyltransferase ; gene expression ; gene regulation ; NS-20Y cells ; cAMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Regulation of the human choline acetyltransferase gene by 8-bromo-cAMP was investigated by transfecting into NS-20Y cells choline acetyltransferase promoter sequences fused to the reporter gene firefly luciferase. Promoter activity was localized to nucleotides −163 to +73. This region of the gene responded to 8-bromo-cAMP in a similar fashion as the endogenous enzyme. However, nearly the same induction was observed for constructs containing unrelated promoters. Furthermore, fusion of the choline acetyltransferase gene to the thymidine kinase promoter yielded no increased induction by 8-bromo-cAMP. These results suggest that cAMP regulates choline acetyltransferase gene transcription through an indirect mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00969082
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  • 46
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    Characteristics of the energy-transducing NADH-quinone oxidoreductase ofParacoccus denitrificans as revealed by biochemical, biophysical, and molecular biological approaches (1993)
    Springer
    Journal of bioenergetics and biomembranes 25 (1993), S. 339-345 
    Details
    ISSN: 1573-6881
    Keywords: NADH-quinone oxidoreductase ; Paracoccus denitrificans ; gene cluster ; H+ pump ; gene expression ; FMN ; iron-sulfur cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract A comparison of the mitochondrial NADH-ubiquinone oxidoreductase and the energy-transducing NADH-quinone oxidoreductase (NDH-1) ofParacoccus denitrificans revealed that both systems have similar electron-transfer and energy-transduction pathways. In addition, both complexes are sensitive to the same inhibitors and contain similar electron carriers, suggesting that theParacoccus NDH-1 may serve as a useful model system for the study of the human enzyme complex. The gene cluster encoding theParacoccus NDH-1 has been cloned and sequenced. It is composed of 18,106 base pairs and contains 14 structural genes and six unidentified reading frames (URFs). The structural genes, URFs, and their polypeptides have been characterized. We also discuss nucleotide sequences which are believed to play a role in the regulation of the NDH-1 gene cluster andParacoccus NDH-1 subunits which may contain the binding sites of substrates and/or electron carriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00762459
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  • 47
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    Electronic Resource
    Methodology of using vaccinia virus to express foreign genes in tissue culture (1993)
    Springer
    Methods in cell science 15 (1993), S. 72-81 
    Details
    ISSN: 1573-0603
    Keywords: vaccinia virus ; orthopox virus ; recombination ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A basic technique is described for inserting any foreign gene into poxvirus by in vitro recombination. Also described is a method for identifying and plaque-purifying recombinant poxvirus containing the foreign gene using nitrocellulose filters and DNA hybridization. Immunologic techniques are presented for analyzing expression of the foreign gene, either on the surface membrane or inside infected cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01667365
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  • 48
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    Variations in the distribution of motor end-plates in the avian pectoralis (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 65-88 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Most avian muscles consist of serially arranged, overlapping fibers that do not extend the length of the muscle. This condition appears to be plesiomorphic with respect to diapsid reptiles. The presence of this serialfibered architecture is evidenced by bands of stained motor end-plates (meps) perpendicular to the columns of fibers and dividing each column into a series of “segments.” The avian pectoralis was chosen for a study of variation in the distribution of meps within a single muscle. We report the interspecific variation for 158 specimens in 63 species. We also use additional specimens to examine intraspecific variation.Setting aside hummingbirds, which have an unique and clearly derived condition, the number of mep bands along a column of fibers near the shoulder falls within a remarkably small range. The number of segments is not obviously related to phylogenetic relatedness or to any characteristic of flight or ecology and is only slightly related to size. The largest specimens do average more segments per column, but there are no trends among small to medium-sized species, suggesting that there is an upper limit to fiber length. However, the shape of the sternum and pattern of connective tissue in the pectoralis alleviate the need for additional fibers in many large birds. These findings suggest that the architecture of the avian pectoralis is subject to some as yet unexplained selection that stabilizes the number of myofibers and/or motor neurons. The findings provide few clues as to whether the significant factors are phylogenetic, functional, ontogenetic, or some combination of these. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052150105
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150201
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  • 50
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    Morphological and functional bases of durophagy in the queen triggerfish, Balistes vetula (Pisces, tetraodontiformes) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 101-118 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tetraodontiform fishes are characterized by jaws specialized for powerful biting and a diet dominated by hard-shelled prey. Strong biting by the oral jaws is an unusual feature among teleosts. We present a functional morphological analysis of the feeding mechanism of a representative tetraodontiform, Balistes vetula. As is typical for the order, long, sharp, strong teeth are mounted on the short, robust jaw bones of B. vetula. The neurocranium and suspensorium are enlarged and strengthened to serve as sites of attachment for the greatly hypertrophied adductor mandibulae muscles. Electromyographic recordings made from 11 cranial muscles during feeding revealed four distinct behaviors in the feeding repertoire of B. vetula. Suction is used effectively to capture soft prey and is associated with a motor pattern similar to that reported for many other teleosts. However, when feeding on hard prey, B. vetula directly bit the prey, exhibiting a motor pattern very different from that of suction feeding. During buccal manipulation, repeated cycles of jaw opening and closing (biting) were coupled with rapid movement of the prey in and out of the mouth. Muscle activity during buccal manipulation was similar to that seen during bite-captures. A blowing behavior was periodically employed during prey handling, as prey were forcefully “spit out” from the mouth, either to reposition them or to separate unwanted material from flesh. The motor pattern used during blowing was distinct from similar behaviors described for other fishes, indicating that this behaviors may be unique to tetraodontiforms. Thus B. vetula combines primitive behaviors and motor patterns (suction feeding and buccal manipulation) with specialized morphology (strong teeth, robust jaws, and hypertrophied adductor muscles) and a novel behavior (blowing) to exploit armored prey such as sea urchins molluscs, and crabs. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150202
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  • 51
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    Early development of the chick embryo (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 165-182 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of the early chick embryo was investigated, using scanning (SEM) and transmission electron microscopy (TEM). Eggs were obtained from the shell gland by injecting hens intravenously with a synthetic prostaglandin or arginine vasopressin. Embryos were examined during late cleavage (stages IV-VI, Eyal-Giladi and Kochav, '76), formation of the area pellucida (stages VII-XI), and formation of the hypoblast (stages X-XIV). SEM highlighted the reduction in cell number at the underside of the embryo during formation of the area pellucida although it became apparent that the thickness of the embryo is not reduced to a single layer of cells at stage X. In addition, blastomeres at the perimeter of embryos (stages V-VI) project filopodial extensions onto a smooth membrane that separates the sub-embryonic cavity from the yolk. During hypoblast formation, epiblast cells generate stellate projections at their basal aspect, thus providing a meshwork for the advancing secondary hypoblast cells. By stage XII the epiblast was one cell thick and reminiscent of a columnar epithelium when viewed transversely. Cells of the deep portion of the posterior marginal zone were distinguished morphologically in the stage XII embryo by their many cell surface projections and ruffled appearance. Blastomeres at the perimeter of stage V-VI embryos projected filopodial extensions onto a smooth membrane which separates the sub-embryonic cavity from the yolk. This membrane is presumed to be confluent with the cytolemma. Evidence is presented demonstrating the presence of intracellular membrane-bound droplets which are hypothesised to contain sub-embryonic fluid. © 1993 Wiley-Liss, Inc.
    Additional Material: 41 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150205
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  • 52
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    Land crabs with smooth lungs: Grapsidae, Gecarcinidae, and Sundathelphusidae ultrastructure and vasculature (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 245-260 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The highly terrestrial grapsids and gecarcinids and the amphibious sundathelphusids all have large, expanded branchial chambers. The lining of the branchial chambers is smooth and well vascularized, and it functions as a lung. The respiratory membrane and the cuticle lining the lung are extremely thin (200-350 nm). The blood vessels within the lung are formed from connective tissue cells supported by collagen fibres and lined by a basal lamina. The major vessels in the lung are embedded deep in the branchiostegite and lie just beneath the thick outer carapace. These vessels branch towards the respiratory membrane, where they eventually lose their connective tissue coverings to form thin, flattened lacunae directly below the respiratory epithelium. The lacunae (exchange sites) are bordered by specialized connective tissue cells, which either bear microvilli on their apical surface (fimbriated cells) or are very smooth. The respiratory circulation in the lung is very complex, with two portal systems present between the afferent and efferent systems, producing a total of three lacunal exchange beds. Portal systems increase the surface area available for gas exchange. The major distributing vessel in the lung is the branchiostegal vein, which runs along the inner margin of the branchiostegite. The main venous supplies come anteriorly from the infraorbital and ventral sinuses and posteriorly from the procardial sinus. The main collecting vessel is the pulmonary vein, which arises anteriorly and which runs around the ventral perimeter of the branchiostegite before emptying into the pericardial sinus. © 1993 Wiley-Liss, Inc.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150306
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  • 53
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    Naturally occurring diblastodermic eggs in the annual fish Cynolebias: Implications for developmental regulation and determination (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 301-312 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Annual fish development differs from that of other teleosts because a phase of blastomere dispersion-reaggregation spatially and temporally separates epiboly from embryogenesis. The fate of dispersed blastomeres was assessed in diblastodermic eggs of the annual fishes Cynolebias whitei and C. nigripinnis. In typical teleosts, blastomere determination and the events of primary embryonic induction occur prior to or during epiboly, so diblastodermic eggs produce partially or completely duplicated embryos. In the diblastodermic eggs of Cynolebias, the two blastoderms are completely separate from the one cell stage to the high blastula. Blastoderm fusion begins during midepiboly. By the end of epiboly, blastoderm fusion has been completed, and the deep, embryo-forming blastomeres of both blastoderms have completely dispersed and intermingled to form a single cell population. A typical annual fish dispersed blastomere phase ensues. Blastomeres reaggregate into a single mass, in which one embryo develops. When hatched, the young fish have no obvious structural or functional abnormalities. We suggest that the dispersed blastomeres of annual fish eggs are equivalent and that induction or determination takes place within the reaggregate. Alternatively, dispersed cells are partially determined but highly regulative, so that, when two populations fuse, the cells sort out according to tissue type and form a single embryo. In either instance, the formation of a single, normal embryo seems to corroborate the hypothesis that the dispersed cell phase of annual fishes is an adaptation that prevents environmentally induced developmental defects. © 1993 Wiley-Liss, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150309
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    Morphological analysis of tendinous structure in the American alligator jaw muscles (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 171-181 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the American alligator, the jaw muscles show seven bundles of tendinous structure: cranial adductor tendon, mandibular adductor tendon, lamina anterior inferior, trap-shaped lamina lateralis, lamina intramandibularis, lamina posterior, and depressor mandibular tendon (originating from the musculus depressor mandibulae, m. pseudotemporalis, m. adductor mandibulae posterior, m. adductor mandibulae externus, m. intramandibularis, m. pterygoideus anterior, and m. pterygoideus posterior). These tendinous structures are composed of many collagen fibrils and elastic fibers; however, the distributions and sizes of the fibers in these tendinous components differ in comparison with those of other masticatory muscles. The differences of these properties reflect the kinetic forces or the stretch applied to each tendon by the muscle during jaw movements in spite of the simple tendon-muscle junctions. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052170206
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    The horizontal septum: Mechanisms of force transfer in locomotion of scombrid fishes (Scombridae, Perciformes) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 183-204 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe the complex shapes of myomeres and myosepta in the mackerels and tunas (Scombridae: Teleostei), and we reveal the orientation of two major systems of collagen fibers in myosepta and horizontal septa with respect to points of attachment to skeleton and skin. Our goal is to identify the likely pathways of the transmission of muscle forces during locomotion. Our primary conclusions are (1) that the collagen fibers of myosepta, horizontal septa, and skin are the organs that transfer locomotor forces from the contraction of myomeres to the backbone and caudal fin during locomotion, and (2) that locomotor muscle pulls against a three-dimensional structure of tendons, septa, and skin that is kept in tension by the radial expansion of the contracting muscle. The main horizontal septum is formed by the convergence of myosepta and is likely to be the major transmitter of muscle force to the axial skeleton. The geometry of the myomeres, the position of red muscle, and particularly the geometric conformation of crossed-fiber arrays of collagen in the main horizontal septum suggest specific mechanisms for the transfer of muscle force to the backbone among scombrid fishes. Morphometrics and the construction of physical models help us to identify musculoskeletal mechanisms of locomotion, and we present two quantitative models of locomotor mechanics in fishes. © 1993 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052170207
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    Oviductal morphology and eggshell formation in the lizard, Sceloporus woodi (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 205-217 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Despite a great deal of work in recent years on the structure of reptilian eggshells, few studies have examined the structure and regulation of the female reproductive tract in the formation of eggshell components, and none have examined the entire process from ovulation to oviposition. In this study, we examined oviductal structure in the oviparous lizard, Sceloporus woodi, followed changes in oviductal structure during gravidity, and determined uterine function in the formation of eggshell components. The endometrial glands of the uterus produce the proteinaceous fibers of the eggshell membrane mainly during the first 24 hours following ovulation, and the fibers are secreted intact and subsequently wrapped around the in utero eggs. Eggshell fibers of different thicknesses are layered around each egg, ranging from an inner layer of thick fibers that gradually become thinner medially and finally forms an outer layer of densely packed particulate matter. These changes in the fibrous layer are reflected by the thickness and length of fibers released from the endometrial glands. Calcium deposition occurs from 3 days following ovulation through day 14 (oviposition) and is accompanied by cellular changes in the luminal epithelium suggestive of secretory activity. Deposition of the eggshell components within the uterus occurs on all eggs simultaneously, rather than sequentially. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052170208
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    Morphogenesis and ductal development of the prostatic complex of the guinea pig (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 219-227 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphogenesis of glandular architecture of the three lobes of prostate gland of the guinea pig, lateral, dorsal, and coagulating gland was studied from 35 days gestation to 90 postnatal days. Epithelial ductal tubules of various lobes of the gland were microdissected after treatment by collagenase and displayed two dimensionally. The number of ductal tips was counted, and the volume of the ductal network was quantified using a graphic tablet. The results show that the growth and ductal morphogenesis fall into two phases: prenatal and postnatal. The first outgrowth of prostatic buds begins at 35 days gestation (gestational length is 65 days). Ductal growth and branching continues over the next 15-20 days and by 55 days gestation, approximately 60%, 79%, and 71% of the adult number of ductal tips of the lateral and dorsal lobes and coagulating gland respectively, are formed. The figures increase to 89%, 84%, and 106%, respectively, by birth. There is little increase in number of ductal tips thereafter. Postnatal growth is accomplished mainly by elongation of existing ductal network with a little additional branching but with an increase in size (volume) of the tubules. Canalization of ductal tubules occurs prenatally in all lobes but postnatal functional cytodifferentiation takes a slightly different pace among them. Ductal morphogenesis of the guinea pig prostate gland differs significantly in time-course from that of the mouse in which ductal development occurs mainly postnatally. © 1993 Wiley-Liss, Inc.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052170209
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052170301
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    Structure of comblike teeth of the ayu sweetfish, Plecoglossus altivelis (Teleostei: Isospondyli): I. Denticles and tooth attachment (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 229-238 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure and tooth attachment of the comblike teeth and denticles of the ayu sweetfish, Plecoglossus altivelis, were examined by light and scanning electron microscopy. The denticle is composed of a spoonlike crown with a spine pointed anteriorly, a triangular plate in the cervical region, and a root that curves laterally and tapers off to a point. The root apex is fused with a long thin pedicle that turns abruptly anteriad toward the jaw bone. Planes of the spine, the spoonlike crown, the triangle plate and the root of the denticle are varied, and the denticle is twisted in the region of the triangle plane.The superficial layer of the dentine is homogeneously calcified and is considered to be enameloid, because some of the inner dentinal epithelial cells in the tooth germ are columnar and possess cellular processes at their apical ends. The dentine is fibrous and fine dentinal tubules are visible in dentine treated with sodium hydroxide and observed by scanning electron microscopy. The upper half of the root is surrounded by a dense layer of collagen fibers running parallel to the tooth axis, and the lower half is encompassed by interlaced collagen fibers. The lower part of the root is open on its lingual side. The pedicle is a long rod which is homogeneously calcified and enmeshed by interlaced collagen fibers, and it curves mediad as it nears the jaw bone. The pedicles are interposed between a layer of gelatinous connective tissue and the jaw bone and terminate on the periosteum. Comparative aspects of ayu tooth morphology are discussed. © 1993 Wiley-Liss, Inc.
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    Effects of juvenile hormone analogues upon soldier differentiation in the termite Reticulitermes santonensis (Rhinotermitidae, Heterotermitinae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 239-261 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Under the influence of juvenile hormone analogues (JHAs), termite workers are induced to differentiate into soldiers. In Reticulitermes santonensis, such induced differentiation is often incomplete, resulting in intercaste production. The morphology of the structures most affected during differentiation was analyzed descriptively and biometrically in normal workers, presoldiers, and soldiers, and in experimental intercastes. We observed that intercastes form a morphological and biometrical continuum between workers and presoldiers (presoldier intercastes), and between presoldiers and soldiers (soldier intercastes). We also compared the biochemistry of the normal individuals and of the intercastes; in contrast to workers, the intercastes possess a frontal gland secretion which differs from those of the presoldiers and soldiers. Besides intercaste characterization, we consider the mode of action of JHAs in termite differentiation. © 1993 Wiley-Liss, Inc.
    Additional Material: 41 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052170211
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    Microtopography of Nippostrongylus brasiliensis (Nematoda: Heligmosomatidae): Free-living larval stages (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 263-271 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtopographic features of the various growth stages of the three free-living larval stages of the rat hookworm Nippostrongylus brasiliensis (Nematoda) were surveyed by scanning electron microscopy. These worms have a rounded anterior end and an elongated tail. Cuticular annulations were observed along the body, which also bore two ribbon-like lateral alae. Two rings of six lip-like lappets were observed around the triradiate oral opening in all larval stages. The cephalic space contained two lateral amphidial pits. The excretory pore in the third anterior part was observed in a ventral view of the larvae. No deirids were observed. The anus with a crescent-shape opening was located posteriorly. Phasmidial apertures, only observed in the third-stage larvae, opened on the lateral alae in the tail region. © 1993 Wiley-Liss, Inc.
    Additional Material: 28 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052170302
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    Two different patterns of interrupted spermatogenesis in winter diapause and summer quiescence in the desert beetle, Omorgus freyi (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 347-358 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spermatogenesis discontinues during both adult reproductive diapause and quiescence in the flightless males of Omorgus freyi. During both types of dormancy, spermatogenesis discontinuity is a dynamic process involving an uninterrupted supply of primary spermatocytes that undergoes partial development and lyses before spermatozoa can be formed. Notwithstanding this common feature, the pattern of discontinuity differs between the two kinds of dormancy. During reproductive diapause, spermatozoa and late spermatids are the first cells that lyse; after diapause break, spermatozoa are produced anew. During quiescence, in contrast, the first indication of discontinuity is the degeneration of late primary spermatocytes; spermatozoa apparently remain intact for a while but eventually degenerate as well. Therefore, males returning to sexual activity after a short period of quiescence may still have spermatozoa capable of fertilization. However, following a long period of quiescence, spermatozoa will be absent and must be produced anew, as in postdiapausing males. The existence of two different patterns of spermatogenesis discontinuity may indicate that each is controlled differently by the endocrine system, in response to the different environmental conditions inducing quiescence or diapause. Dual control of discontinuity may contribute to the high reproductive potential of these flightless beetles, under unpredictable and extreme desert conditions. © 1993 Wiley-Liss, Inc.
    Additional Material: 18 Ill.
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150101
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    Structure of recent and fossil mysid statoliths (Crustacea, Mysidacea) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 31-49 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Statoliths of 61 Recent species representing all subfamilies of Mysidae were studied with special emphasis on internal structure. In addition 5 samples of fossil statoliths from Miocene deposits were examined. Species of Boreomysinae and Rhopalophthalminae show simple roughly spherical organic statoliths, with setae originating from the sensory cushion and anchored in the statolith with distal branches extending shortly below the surface. All other subfamilies possess mineralized statoliths of greater structural complexity, with differentiation in core and mantle, where each part may consist of up to three layers. Habitus is hemispherical to discoidal. External gross structures are dorsal tegmen, ventral fundus, and the ambitus forming the outer toroidal to semi-toroidal circumference. Setae penetrate the mantle through mineralic canals and insert on the surface of the core. As suggested by congeneric species of Schistomysis, there is no principal structural difference between statoliths mineralized with fluorite compared to vaterite. However, vaterite statoliths tend to be more often of moruloid appearance and are exceptional by showing a central conical hole (the hilum) or a central cavity in certain forms. These structures are typical of fossil calcite statoliths. In vaterite and fluorite statoliths, the mantle shows radially arranged (= spherulitic) crystal aggregates. Such arrangements are badly preserved in fossil calcite statoliths. In large extant statoliths, concentric structures, mainly in the form of superficial striation and/or concentric microstrata, are visible in coexistence with radial aggregates. Stratification is possibly due to stratified deposition of the nonmineralized gland product, while the spherulitic structure is indicative of subsequent radial growth of crystal aggregates. The structure of accessory fluorite statoliths in the statocyst of Mesopodopsis slabberi leads to the hypothesis that mantle material is formed by secretions of the caudal statocyst gland. After demineralization of fluorite, vaterite and calcite statoliths, an organic template remains showing most essential morphological features of the statolith. From this we conclude that the structure of the statolith is (almost) entirely matrix mediated. © 1993 Wiley-Liss, Inc.
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    An ultrastructural study of the dorsal lingual epithelium of the crab-eating frog, Rana cancrivora (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 89-100 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The amphibian tongue contains two types of papilla which are believed to function in gustation and in the secretion of salivary fluid. Scanning electron microscopy reveals that columnar, filiform papillae are compactly distributed over nearly the entire dorsal surface of the tongue of the frog, Rana cancrivora, and fungiform papillae are scattered among the filiform papillae. Microridges and microvilli are distributed on the epithelial cell surface of the extensive area of the filiform papillae. Light microscopy shows that the apex of each filiform papilla is composed of stratified columnar and/or cuboidal epithelium and its base is composed of simple columnar epithelium. Transmission electron microscopy reveals that most of the epithelium of the filiform papillae is composed of cells that contain numerous round electron-dense granules 1-3 μm in diameter. Cellular interdigitation is well developed between adjacent cells. On the free-surface of epithelial cells, microridges or microvilli are frequently seen. Between these granular cells, a small number of ciliated cells, mitochondria-rich cells and electron-lucent cells are inserted. In some cases, electron-dense granules are present in the ciliated cells. At higher magnification, the electron-dense granules appear to be covered with patterns of spots and tubules. Overall, the morphology and ultrastructure of the lingual epithelium of the three species of Rana that have been studied are quite similar, but they can be easily distinguished from those of Bufo japonicus. Therefore, it appears that lingual morphology is phylogenetically constrained among members of the predominantly freshwater genus Rana to produce uniformity of papillary structure and this morphology persists in Rana cancrivora despite the distinct saline environment in which it lives. © 1993 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052150106
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    Pigment pattern formation in the larval salamander Ambystoma maculatum (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 151-163 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As part of an ongoing comparative study of pigment patterns and their formation in embryos and larvae of ambystomatid salamanders, Ambystoma maculatum from two differnt populations, one in the northern (New York) and one in the central (Tennessee) United States, were investigated. Scanning electron microscopy was used to study early neural crest development. Light microscopy in combination with markers for the two pigment cell types (xanthophores and melanophores) made it possible to follow pigment cell migration before the pigment cells were fully differentiated. A bilateral pigment pattern consisting of two horizontal melanophore stripes surrounding an interstripe area populated by xanthophores formed in the larvae. In both populations, some variation was present in the form of a continuum ranging from clear horizontal stripes to extreme cases with a random pattern. Unlike the other ambystomatids that have been investigated, the neural crest cells in A. maculatum do not form aggregates and no vertical bars are formed. Instead, both the pattern and its formation are very similar to what has been reported for salamandrids. If pattern formation mechanisms can act as developmental constraints we would expect the A. maculatum pattern to be the primitive condition in the Ambystomatidae, using the Salamandridae as the outgroup. There is no strong support for this when aggregate formation is used as a character and mapped onto phylogenies for the group. The aggregate formation mechanism, and the pigment pattern that it leads to, have most likely been secondarily lost in A. maculatum. © 1993 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052150204
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    A morphologic study of the ductus of the epididymis of Sus domesticus (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 183-193 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The head, body, and tail regions of the epididymal duct (or caput, corpus, and cauda epididymis) in two healthy and sexually mature Sus domesticus males were examined by light microscopy and by scanning or transmission electron microscopy. The epididymal duct is lined with a pseudostratified epithelium with stereocilia and covered by a muscular-connective tissue sheath that is thickest in the tail region. Diameter of the epididymal duct and height of epididymal epithelium are maximal in the head region. Length of the sterocilia and spermatic density are higher in the head and body regions. Somatic cells are abundant in the tail region. The epididymal epithelium is made up of five cell types: basal cells, principal cells, clear cells, narrow cells, and basophilic cells. Abundant secretory units are observed in the supranuclear cytoplasm of columnar principal cells. Each mature secretory unit is constituted by electron-dense secretion granules covered by more than eight layers of cisternae of reticulum between which the mitochondria are intercalated. In the apical cytoplasm the isolated secretion granules become larger and less electron dense. The apical surface is covered by numerous sterocilia. Basal cells are pyramidal and less high than principal cells. The clear cells, arranged between the principal cells, are characterized by the presence of abundant vesicular elements and electron-lucid secretion granules, and by an apocrine secretory process. The narrow cells are characterized by their highly vacuolized cytoplasm. Intermediate cell typologies can be found among basal, principal, clear, and narrow cells, which could be four developmental stages of the same cell type. The basophilic cells are spheroidal and are found at different levels between the epithelial cells and in the connective tissue underlying the epithelium. © 1993 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052150206
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    Testicular and androgen dependence of skin gland morphology in the anurans, Xenopus laevis and Rana pipiens (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 195-200 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In anuran amphibians, there is increasing evidence that exocrine glands dispersed throughout the general integument are secondary sex characters (SSC). Following the recent discovery of sexually dimorphic “breeding glands” in the dorsum of male Rana pipiens, we studied the effects of castration and testosterone treatment on the dorsal skin glands of male Xenopus laevis and R. pipiens to determine whether the dorsal breeding glands, or any other dorsal skin glands, are androgen dependent. The dorsal skin glands of X. laevis were unaffected by androgen status. By contrast, in R. pipiens, breeding, mucous, and seromucous glands responded to testosterone stimulation. Mucous glands were significantly (P 〈 0.05) larger in testosterone-treated frogs than in castrates. There was a large, but statistically insignificant, increase in the size of the dorsal breeding glands. Testosterone treatment also increased the epithelial cell height of breeding and seromucous glands (P 〈 0.05). In the skins of castrated and testosterone-treated frogs, there was a reciprocal relationship between the abundance of seromucous and breeding glands: in castrates, seromucous glands were abundant and breeding glands virtually absent, whereas in testosterone-treated frogs, breeding glands were abundant and seromucous glands less common. The total number of the two gland types was similar in both treatment groups. Glands that appeared to be intermediate in form between seromucous and breeding glands were observed in some frogs. These data suggest that seromucous glands may be the regressed form of breeding glands in the dorsal skin of R. pipiens and that the dorsal skin of R. pipiens is a SSC. © 1993 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052150207
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    Development and fine structure of the bony scutes in Corydoras arcuatus (Siluriformes, callichthyidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 225-244 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development and the structure of the bony scutes have been studied in a growth series of the armored catfish Corydoras arcuatus using light and electron microscopy. Fibroblast-like cell condensations appear in the dermis, in the posterior region of the caudal peduncle, and these will constitute the scute papillae. Collagen bundles of the preexisting dermis colonized by the papilla cells are remodeled and incorporated in the papilla to form, in addition to newly synthesized woven-fibered bony material, the initium of the scute. This process of formation differs from that described for the dermal papilla of an elasmoid scale. During growth, the osteoblasts surrounding the scute constitute the scute sac in which the scute grows. Parallel-fibered bone is deposited on both sides of the initium, and osteoblasts are incorporated within the scute matrix. The remodeling and incorporation of collagen bundles of the preexisting dermis is maintained during growth only in the deep, anterior region of the scute. The posterior region and the upper surface of the scute are close to the epidermal-dermal boundary. When growth slows down in the upper part of the scute, a characteristic, well-mineralized tissue, composed of thin vertical fibrils and granules and devoid of typical striated collagen fibrils, is deposited on the scute surface. A new term, hyaloine, is introduced for this nonosseous, highly mineralized layer constituting the upper part of the scute. Hyaloine shows thin electron-dense lines, which probably correspond to periodic growth arrests. The structure and localization of the hyaloine are compared to other well-mineralized, similar tissues found on the surface of the dermal skeleton in lower vertebrates. © 1993 Wiley-Liss, Inc.
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160101
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    Ultrastructural variations in the spermiogenesis of Triatoma infestans induced by temperature changes (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 17-27 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The reproductive process in insects may be affected by several factors, among which environmental temperature is one of the most important because of the poikilothermic condition of insects. To determine the effect of suboptimal temperature on the spermiogenic process of Triatoma infestans, males were exposed to 12°C for 10 days. In order to determine the reversibility of such alterations, males were returned to 28°C for 10 days after exposure to 12°C. Low temperature caused abnormal changes in the spermiogenic cells such as lack of spermatid orientation, general cyst disorganization, and asynchrony in the development of contiguous cysts. Highly vacuolized areas and pseudomyelinic bodies enclosing isolated or clustered vesicles of different electrodensity were also observed. At the end of the recovery time, cysts with spermatids developed synchronously. However, some presented isolated and clustered vesicles of different size and electrodensity. Some supernumerary organelles were also observed. These abnormal structures were related to processes of autophagy and phagocytosis of degenerating sexual cells. © 1993 Wiley-Liss, Inc.
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    Regionalization of eccrine and spermiophagic activity in spermathecae of the salamander Eurycea cirrigera (Amphibia: Plethodontidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 161-170 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spermathecae of female Eurycea cirrigera are compound alveolar glands; narrow neck tubules connect the distal bulbs to a common tube that opens onto the roof of the cloaca. The common tube and neck tubules produce apical secretory vacuoles that contain a periodic acid-Schiff (PAS)+ substance for merocrine export into the lumen. This substance is produced throughout the year, although secretory vacuoles are less numerous during the period of reproductive inactivity in the summer. When sperm are present, the product from the secretory vacuoles bathes sperm in the lumen. Sperm are in orderly arrays and never are embedded in the cytoplasm of the common tube or neck tubules. The distal bulbs do not produce PAS+ secretory vacuoles, and are actively spermiophagic as long as sperm are present. Sperm become embedded in the epithelium of the distal bulbs where lysosomes degrade sperm. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052180301
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    Ultrastructural study of the ovary of the sessile scyphozoan, Haliclystus octoradiatus (Cnidaria: Stauromedusae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 225-236 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An ultrastructural study of the ovary of the sessible jellyfish, Haliclystus octoradiatus, indicates that it is fundamentally different from that of other scyphozoans and is the most structurally complex within the class. Oocytes develop within a series of spherical, sac-like ovarian follicles consisting of an enlarged intercellular space between two layers of subumbrellar gastrodermis. Developing oocytes are largely restricted to a thin germinal epithelium at the periphery of each follicle and gradually migrate toward the lumen as they mature. Individual oocytes are surrounded by early germ cells and follicle-like accessory cells of presumed somatic origin. Similar folliclelike cells have not been described in the Cnidaria previously. Vitellogenesis appears to involve the combined activity of the Golgi complex and associated rough endoplasmic reticulum. Ovarian morphology may be helpful in deciphering phylogeneitc relationships within the Cnidaria. © 1993 Wiley-Liss, Inc.
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    Rostrate pedicellariae: A morphologically distinct form of echinoid test appendage (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 237-247 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The term rostrate was introduced by Mortensen ('07) to describe a type of pedicellaria he found in spatangoids. These pedicellariae resemble tridentate ones but have arching valves. Unlike the main categories of echinoid pedicellariae, no clear diagnosis of the rostrate form exists. This work examines the detailed morphology of the valves of rostrate pedicellariae observed by light and scanning electron microscopy and compares the shapes and dimensions of their component parts with tridentate pedicellariae. The data reveal considerable differences between the two, which warrant the recognition of rostrate pedicellariae as a distinct form. A diagnosis is given. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    Reproduction, placentation, and embryonic development of the Atlantic sharpnose shark, Rhizoprionodon terraenovae (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 257-280 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Atlantic sharpnose shark Rhizoprionodon terraenovae (Richardson) is a small carcharhinid that is a common year-round resident along the southeast coast of the United States. It is viviparous and its embryos develop an epithelio-vitelline placenta. Females enter shallow water to give birth in late May and early June. Mating occurs shortly after parturition, and four to seven eggs are ovulated. Fertilized eggs attain the blastoderm stage in early June to early July. Separate compartments for each egg are formed in the uterus when the embryos reach 3-30 mm. Embryos depend on yolk for the first 8 weeks of development. When embryos reach 72 mm their yolk supply is nearly depleted and they shift to matrotrophic nutrition. When the embryos reach 40-55 mm, placental development begins with the vascularization of the yolk sac where it contacts the uterine wall. Implantation occurs at an age of 8-10 weeks by which time the embryos reach 70-85 mm. The expanding yolk sac engulfs the maternal placental villi, and its surface interdigitates with the villi to form the placenta. The rest of the lumenal surface of the uterus is covered by non-placental villi that appear shortly after implantation. Histotrophe production by the non-placental villi begins just after their formation. The placenta grows continuously during gestation. The egg envelope is present throughout gestation, separating maternal and fetal tissues. Embryos develop numerous appendiculae on the umbilical cord. Young sharks are born at 290-320 mm after a gestation period of 11 to 12 months. © 1993 Wiley-Liss, Inc.
    Additional Material: 15 Ill.
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    The male reproductive system and mechanism of sperm transfer in Argulus japonicus (Crustacea: Branchiura) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 51-63 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The histomorphology of the male reproductive system and surface morphology of the “peg-and-socket” in Argulus japonicus are described from serial sagittal and transverse sections and scanning electron micrographs. The prostate complex consists of a glandular part, a reservoir for storing the secretion, and an efferent duct opening into the ejaculatory duct. The openings of both the vas deferens and the prostate duct into the ejaculatory duct are guarded by sphincters. The ejaculatory ducts, which are lined by tall columnar epithelial cells, do not open into the cuticle-lined genital atrium but are blind-ending tubes. This observation and results obtained from observing live specimens, as well as the fact that no spermatophores are formed, suggest that semen could leave the ejaculatory duct only after puncturing of its walls. It is suggested that sperm transfer is accomplished in the following manner: during copulation contraction of the muscular walls of the vas deferens and prostate duct causes semen to be pumped into the ejaculatory duct, which is then closed off by sphincters and a high internal pressure is developed. When a spermathecal spine penetrates the walls of the ejaculatory duct, semen flows from the ejaculatory duct into the spermathecal vesicle due to the higher pressure in the ejaculatory duct. This mechanism is analogous to the sucking up of fluid with a hypodermic syringe. © 1993 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
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    Anatomy of the larva of Amathia vidovici (Bryozoa: Ctenostomata) and phylogenetic significance of the vesiculariform larva (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 1-29 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Amathia vidovici (Vesiculariidae) has a lecithotrophic coronate larva. The apical disc of A. vidovici larvae is more complex than that of other vesiculariids and includes a new cell type, which may be glial-like in function. A massive nerve nodule consists only of neural processes; as no ganglia or other evidence of interneurons were found, sensory cells apparently innervate their effectors directly. Putative synaptic junctions within the nerve nodule indicate that both receptor and effector cells send processes to this neuropile. Some 44 intercoronal cells of three types, two of which are new, are interspersed among the approximately 40 coronal cells. Juxtapapillary bodies, a unique sensory complex previously known only from Bowerbankia gracilis larvae, also occur in A. vidovici. A large refractile body, which is of uncertain function and is positioned near the center of the larva, is described for the first time.A comparison of vesiculariid larvae that have been studied at the ultrastructural level reveals that larvae of Amathia vidovici and Bowerbankia gracilis are more similar to each other than either is to B. imbricata. Differences between the two Bowerbankia species, however, may reflect relative detail of their study and differences in interpretation rather than intergenic plasticity. Nevertheless. a distinctive suite of larval characteristics are shared by other members of the family Vesiculariidae, justifying a specific name - vesiculariform - for their larvae. A number of the defining characteristics of vesiculariform larvae also appear in the carnosan superfamily Victorelloidae. This finding is consistent with arguments based on adult characteristics that the Victorelloidea are ancestral to the Vesicularioidea. If this geneology is correct, one can predict that those vesiculariform traits which originated in the victorellids are plesiomorphic not only to the Family Vesiculariidae but to all sister taxa placed in the Vesicularioidea. © 1993 Wiley-Liss, Inc.
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    Cranial osteogenesis in Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 119-149 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pattern of onset and general rate of cranial ossification are compared in two marsupials, Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae). In both species a similar suite of bones is present at birth, specifically those surrounding the oral cavity and the exoccipital, and in both postnatal events follow a similar course. The facial skeleton matures more rapidly than the neurocranium, which is characterized by an extended period of ossification. Most dermal bones begin ossification before most endochondral bones. Endochondral bones of the neurocranium are particularly extended in both the period of onset of ossification and the rate of ossification. These data confirm suggestions that morphology at birth is conservative in marsupials and we hypothesize that the pattern of cranial osteogenesis is related to two distinct demands. Bones that are accelerated in marsupials are correlated with a number of functional adaptations including head movements during migration, attachment to the teat, and suckling. However, the very slow osteogenesis of the neurocranium is probably correlated with the very extended period of neurogenesis. Marsupials appear to be derived relative to both monotreme and placental mammals in the precocious ossification of the bones surrounding the oral cavity, but share with monotremes an extended period of neurocranial osteogenesis. © 1993 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052150203
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150301
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    Falciparum malaria in naturally infected human patients: I. Ultrastructural differences between malaria pigments in intraerythrocytic asexual and sexual forms (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 201-206 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Venous blood samples were taken from patients naturally infected with the human malaria parasite Plasmodium falciparum. Two types of malaria pigment (MP) particles have been demonstrated in intraerythrocytic asexual forms (trophozoites and schizonts), while a single type was detected in gametocytes. Type I MP particles, found in both asexual and sexual forms, are electron-dense. It is suggested that these are proteinaceous and may be intermediate, utilizable metabolic products that serve as a food reserve during development of the parasite in the human host and also during the growth cycle of the sexual form in the mosquito. In asexual forms, type I particles occur within food vacuoles (FV) containing semidigested hemoglobin (Hg), while they are unenveloped in the cytoplasm of the sexual forms. Type II MP particles, found in electron-lucent residual bodies, are crystalloid and of low electron density. It is suggested that these are the final, waste product of Hg digestion in the asexual forms. © 1993 Wiley-Liss, Inc.
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    Falciparum malaria in naturally infected human patients: II. Ultrastructural alterations to erythrocytes infected with asexual forms (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 207-212 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural alterations of human erythrocytes infected with asexual forms of Plasmodium falciparum were studied in naturally infected Saudi patients. These included surface knobs and nodules as well as invaginations associated with cytopasmic vesicles observed in erythrocytes infected with asexual forms of the parasites. Such nodules and surface invaginations have been previously described only in erythrocytes infected with P. ovale and P. vivax, respectively. Within the cytoplasm of infected erythrocytes were membrane-bound clefts, similar to those that appear to be a common characteristic in all red cells infected with malaria parasites. Vacuolations were often seen in the peripheral cytoplasm and may represent hemolyzed areas. Collapsed cells with an internal-lucent interior and surrounded by an irregularly folded membrane may represent completely hemolyzed erythrocytes. © 1993 Wiley-Liss, Inc.
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    A microscopic investigation of the lymphoid organs of the beluga, Delphinapterus leucas (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 261-287 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lymphoid organs from belugas, Delphinapterus leucas, ranging in age from less than one to 16 years, were harvested during a sanctioned hunt to investigate morphology. The spleen is divisible into red and white pulp and a stroma consisting of a reticular network, a collagenous capsule, and trabeculae containing smooth muscle bundles. White pulp areas appear to be devoid of follicles and consist mainly of periarteriolar lymphatic sheaths (PALS), that are larger in younger than in older belugas. Definitive marginal zones between red and white pulp are difficult to discern in older belugas. Lymph nodes are similar to those of other mammals; they possess a follicular cortex surrounding a vascular medulla composed of lymphatic cords and sinuses. Smooth muscle is abundant in the medullary region, usually in close proximity to sinuses. The expansive nodular mass at the root of the mesentery, often referred to as the “pseudopancreas,” is similar to lymph nodes in microscopic architecture. Pharyngeal tonsils and gut-associated lymphoid tissue (GALT) are found along the digestive tract and display an “active” morphology. Tonsils are comprised of lobules of follicles separated by vascular connective tissue. Epithelial-lined crypts communicate with the pharyngeal lumen. GALT consists of diffuse and follicular lymphocytes within the intestinal mucosa and submucosa. The thymus is well developed in the younger belugas, with lobules divisible into densely packed cortical zones of thymocytes and more loosely arranged medullary lymphocytes. Hassall's corpuscles are occasionally visible within the medulla. Cetaceans diverged evolutionarily from other mammals over 55 million years ago. This study investigates changes in lymphoid organ morphology in a species that now inhabits a unique ecological niche. This study also lays the groundwork for functional investigation of the beluga immune system, particularly as it relates to differences between healthy and stranded animals. © 1993 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052150307
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    Gliding flight in the American Kestrel (Falco sparverius): An electromyographic study (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 213-224 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Electromyographic (EMG) activity was studied in American Kestrels (Falco sparverius) gliding in a windtunnel tilted to 8 degrees below the horizontal. Muscle activity was observed in Mm. biceps brachii, triceps humeralis, supracoracoideus, and pectoralis, and was absent in M. deltoideus major and M. thoracobrachialis (region of M. pectoralis). These active muscles are believed to function in holding the wing protracted and extended during gliding flight. Quantification of the EMG signals showed a lower level of activity during gliding than during flapping flight, supporting the idea that gliding is a metabolically less expensive form of locomotion than flapping flight. Comparison with the pectoralis musculature of specialized gliding and soaring birds suggests that the deep layer of the pectoralis is indeed used during gliding flight and that the slow tonic fibers found in soaring birds such as vultures represents a specialization for endurant gliding. It is hypothesized that these slow fibers should be present in the wing muscles that these birds use for wing protraction and extension, in addition to the deep layer of the pectoralis. © 1993 Wiley-Liss, Inc.
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    Evolution and functional significance of tendon ossification in woodcreepers (Aves: Passeriformes: Dendrocolaptinae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 289-300 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The woodcreepers, a clade of scansorial, neotropical birds, are distinctive among passerines in having extensive tendon ossification. Dissection of 42 of the 50 species indicates that such ossification in the hindlimb is limited almost entirely to tendons of insertion of the crural muscles. Most crural muscles have ossifications, and in all but one the ossified tendons are long and thin. Preliminary dissection revealed a similar pattern among ossified wing tendons. Phylogenetic analysis suggests that extensive tendon ossification is a synapomorphy of the woodcreepers. The species of Dendrocincla, which form a clade, show secondary reduction of ossification in some tendons, which may be correlated with increased intraspecific variation and with an expansion of foraging habits and postures to include nonscansorial behaviors. In contrast, the larger woodcreepers, other than Drymornis bridgesii and Nasica longirostris, form a clade with virtually no loss in ossification or evidence of intraspecific variation, even in large series of two species. Phylogenetic losses do not occur for the primary flexor of the ankle (M. tibialis cranialis), whereas two extensors (Mm. fibularis longus and gastrocnemius pars lateralis) show a complex pattern of derivation and loss. Previous biomechanical studies demonstrate that ossification increases the stiffness of tendons, making them stretch less under a given force. These structural and phylogenetic patterns are consistent with the view that hindlimb tendon ossification in woodcreepers is an adaptation to resist increased forces that act to extend the limb during vertical climbing. © 1993 Wiley-Liss, Inc.
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    Follicular dynamics and germinal bed activity during the annual ovarian cycle of the lizard, Calotes versicolor (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 1-7 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Changes in size frequency distribution of extrastromal follicles, atretric follicles (AF), and the number of oogonia, oocytes, and primordial follicles in the ovaries are studied in Calotes versicolor during its annual reproductive cycle. Extrastromal follicles were graded into stages I to VI based on their diemeter. Stage I (0.5-0.75 mm) follicles are found throughout the year. The recruitment of stage II (0.76-1 mm) and stage III (1.10-2 mm) follicles occurs during December and March, respectively. Follicles of stage I-III are found in greater number in May. Stage IV vitellogenic follicles (2.10-3 mm) are recruited in April. Advanced vitellogenic follicles (stage VI) are formed between May and August. From April to August, the ovaries of lizards contain vitellogenic follicles of stages IV or V or VI suggesting that once a set of follicles enters vitellogenic phase there is no recruitment of another set of vitellogenic follicles from previtellogenic follicles until the former ovulates. The presence of vitellogenic follicles and at least two sets of CL in July-August suggest that C. versicolor may oviposit at least three clutches of eggs per season. The clutch size in this lizard varies from a maximum 24 eggs in May to a minimum of 13 eggs in September. The previtellogenic AF are found throughout the year. Atresia is more prevalent in stage III suggesting that these follicles are more prone to become atretic. Interestingly, atresia of vitellogenic follicles occurs rarely. Each ovary in C. versicolor has two germinal beds. The germinal beds contain a greater number of oogonia (536-696), primary oocytes (40-71), and primordial follicles (32-55) during prebreeding and early breeding phases of the ovarian cycle. © 1993 Wiley-Liss, Inc.
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    Ultrastructure of the spermatozoon of the teleost fish Acanthopagrus schlegeli (Perciformes: Sparidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 29-33 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructurally the spermatozoon of Acanthopagrus schlegeli (Sparidae) has a spherical, homogeneously electron-dense nucleus with a deep axial nuclear fossa, and an unusual notch, shaped like a bowtie, in the nuclear region. The short midpiece contains four spherical mitochondria and encircles the basal body of the flagellum. It is concluded that the spermatozoon is of a primitive type, although it is characterized by several unique features which may provide useful systematic characters. © 1993 Wiley-Liss, Inc.
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    In-series fiber architecture in long human muscles (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 35-45 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fiber architecture of adult human sartorius and gracilis muscles was examined using a combination of fiber microdissections and histological methods. Intact fibers were dissected from fascicles of muscle strips that were digested in nitric acid. All of these fibers terminate intrafascicularly by tapering to a fine strand at one or both ends. They measure 4-20 cm after correction for shrinkage. Systematic dissections of 1 cm long blocks sampled at intervals along the muscle length suggest that tapered fiber endings occur at all locations along the muscle but are most common centrally; here they accounted for up to 14% of dissected fibers in each block. Transverse sections of muscle confirm that fiber profiles with small diameters occur at all levels of the muscle but are especially common in sections more than 5 cm from its origin or insertion. The architectural arrangement demonstrated here suggests that long human muscles, like muscles in other species, are composed of relatively short, in-series fibers. This has many implications for the neural activation and force-developing behavior of these muscles that must be considered when paralyzed muscles are reanimated using electrical stimulation. Further, it may predispose long muscles to certain types of neuromuscular damage and dysfunction. © 1993 Wiley-Liss, Inc.
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    Suboccipital muscles in the cat neck: Morphometry and histochemistry of the rectus capitis muscle complex (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 47-63 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphometry, histochemistry, and biomechanical relationships of rectus capitis muscles were examined in adult cats. This family of muscles contained six members on the dorsal, ventral, and lateral aspects of the upper cervical vertebral column. Three dorsal muscles (rectus capitis posterior major, medius, and minor) formed a layered complex spanning from C1 and C2 to the skull. Rectus capitis posterior major was composed predominantly of fast fibers, but the other two deeper muscles contained progressively higher proportions of slow fibers. One ventral muscle, rectus capitis anterior major, was architecturally complex. It originated from several cervical vertebrae and appeared to be divided into two different heads. In contrast, rectus capitis anterior minor and rectus capitis lateralis were short, parallel-fibered muscles spanning between the skull and C1. The ventral muscles all had nonuniform distributions of muscle-fiber types in which fast fibers predominated. Dorsal and ventral muscle groupings usually had cross-sectional areas of 0.5 cm2 or more, reflecting a potential capacity to generate maximal tetanic force in excess of 9 N. Biomechanical analyses suggested that one muscle, rectus capitis lateralis, had its largest moment in lateral flexion, whereas the other muscles had large, posturally dependent moment arms appropriate for actions in flexion-extension. The observation that most rectus muscles have relatively large cross-sectional areas and high fast-fiber proportions suggests that the muscles may have important phasic as well as postural roles during head movement. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160107
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    Organization of hematopoietic tissue in the intermolt lobster, Homarus americanus (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 65-78 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Hematopoiesis in the American lobster Homarus americanus, as in most decapod crustaceans, occurs in a thin tissue covering the dorsal surface of the foregut. This tissue is composed of loosely attached, ovoid lobules containing the hematopoietic precursors and maturing hemocytes. Release of hemocytes into the dorsal hemocoel is accomplished by rupture of a portion of the connective tissue capsule covering the lobule. Cross sections of the lobules contain between 6 and 40 hematopoietic cells, of which approximately 90% constitute stages in granulocyte maturation and 10% are intermediates in hyaline cell maturation. Hematopoietic precursors in these two lines are similar to those recently described in a penaeid shrimp Sicyonia ingentis. The mitotic rate averaged 5.1% (range = 0.7% to 15.8%) in intermolt lobsters, 90% comprised granulocyte precursors. © 1993 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160108
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  • 91
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    Structural characteristics of marsupial brood pouches of the antarctic sea urchins Abatus nimrodi and Abatus shackletoni (Echinoidea: Spatangoida) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 79-93 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Marsupial spines, tubercles, and pedicellariae of the antarctic brooding spatangoids Abatus nimrodi and Abatus shackletoni have been examined by scanning electron microscopy. Individual brood pouches of A. nimrodi may hold up to 28 embryos and juveniles and those of A. shackletoni may hold up to 38 lecithotrophic embryos and juveniles. Juveniles can be divided into (a) those with early development of external elements and a mean size of 2.0 and 1.6 mm, respectively, and (b) those equipped with fully developed external elements and a mean length of 4.3 and 2.8 mm, respectively. Mean diameters of aboral brood pouch openings of A. nimrodi and A. shackletoni were 6.5 and 4.1 mm, respectively. Brood pouches contain tall, distally enlarged spines, and smaller, layered cover-spines, which form a protective arch over the marsupia. There are also slender brood-pouch-bottom spines, which have an extremely thickened spinal epidermis. A. nimrodi has mainly bidentate, but also triand quadrodentate pedicellariae. A. shackletoni has two forms of tridentate, rostrate, and globiferous pedicellariae. In A. shackletoni, marsupial spine density is significantly lower than in A. nimrodi. These differences may be related to distinct sediment characteristics in their respective habitats. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160109
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  • 92
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    Announcement (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 113-113 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160111
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160201
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  • 94
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    Ultrastructure of prothoracic glands during larval-pupal development of the tobacco hornworm, Manduca sexta: A reappraisal (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 95-112 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of Manduca sexta prothoracic glands was investigated using a protocol that preserves membranes. During the last larval stadium, prothoracic gland cells increase in diameter, volume, protein content, and perhaps number, enhancing their capacity to produce ecdysteroids. The glands' strand-of-cells morphology, their in situ location, the presence of gap junctions between cells, and junctional foot-like structures within cells support previous findings that prothoracicotropic hormone stimulates ecdysteroidogenesis via Ca2+-induced Ca2+ release. A different method of tissue fixation from that previously used to investigate the ultrastructure of Manduca sexta prothoracic glands has revealed a significantly different ultrastructure. These new findings begin to define roles for endoplasmic reticulum and mitochondria in ecdysteroid synthesis and support the hypothesis that the glands secrete the steroid hormone via exocytosis. The structural dynamics of the glands are discussed in the context of the glands' function during Manduca sexta larvalpupal development. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160110
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  • 95
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    Structure and histochemical organization of the spleen of Agama stellio (Sauria: Agamidae) and Chalcides ocellatus (Sauria: Scincidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 115-120 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spleen of Agama stellio is composed mainly of red pulp; the white pulp is poorly developed, and its clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of clear reticular cells intermingled with blood cells, sinusoids, and pigment cells. The spleen of Chalcides ocellatus is encapsulated by connective tissue and is composed of white and red pulp. The white pulp consists of lymphoid tissue that surrounds the central arterioles, forming the periarteriolar lymphocyte sheath (PALS). The red pulp is composed of a system of venous sinuses and cords. The results of various histochemical procedures designed to demonstrate mucosubstances, proteins, and nucleic acids indicate that the spleen in these species resembles the mammalian spleen. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160202
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  • 96
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    Cleavage pattern in embryos of Haliotis tuberculata (Archaeogastropoda) and gastropod phylogeny (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 121-139 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The early cleavage pattern in embryos of the archaeogastropod Haliotis tuberculata strongly resembles the cleavage pattern of the archaeogastropods Trochus and Patella. It typically deviates from the cleavage patterns found in embryos of more advanced Archaeogastropoda, Caenogastropoda (the majority of the meso- and neogastropods), and Euthyneura (opisthobranch and pulmonate gastropods). It is assumed that the cleavage pattern found in Haliotis, Trochus, and Patella represents the ancestral pattern. A regular pattern of heterochronic changes in the succession of the formation of the larval trochoblasts and the stem cell of the adult mesoderm can be observed from the more primitive Archaeogastropoda to the more advanced Euthyneura. This observation strengthens the idea that the early cleavage pattern contains significant phyletic information. © 1993 Wiley-Liss, Inc.
    Additional Material: 33 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160203
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  • 97
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    On the structure of the aortic valves in snakes (Reptilia: Serpentes) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 141-159 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Aortic valve morphology was examined in 32 species of snakes representing 28 genera and 11 families and a diversity of habitat preferences. The results largely agree with previous studies but include some previously undescribed features, such as the cranial displacement of the cusps in the left aorta in some species and the structure of the opposing cusps of the interaortic foramen. Few features of the aortic valves are uniform among species. The pattern of morphological variation does not correlate with simple habitat preference (e.g., terrestrial, arboreal); however, some of the variation, particularly in the valves themselves, correlates with taxonomic relationships. We suggest that the presence of an interaortic foramen, with its associated valve, could result in an interaortic shunt of blood that potentially alters hemodynamics and flow patterns in the systemic circulation of snakes. © 1993 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160204
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  • 98
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    Microstructure, ontogeny, and evolution of scale surfaces in xenosaurid lizards (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 161-177 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Both scanning electron and light microscopy were used to examine the epidermal structure of scales taken from several ontogenetic stages of Xenosaurus grandis and Shinisaurus crocodilurus. In addition, scales from all xenosaurid species were examined by scanning electron microscopy to determine scale surface variation among genera, species, and subspecies. A varied and phylogenetically informative morphology characterizes the scale surfaces of xenosaurid lizards. Scale surface morphology is conservative among the species and subspecies of Xenosaurus, but is more variable between the two xenosaurid genera. Their scale surfaces are characterized by folds in the oberhautchen, beta, mesos, and alpha epidermal layers, forming polygonal ridges of a type previously described for the Iguania. The three species of Xenosaurus possess lenticular scale organs, whereas Shinisaurus has scale organs with spikes (bristles). The spikes of Shinisaurus are formed by the beta and oberhautchen layers, with the alpha layer forming a dome-shaped cap over a dermal papilla. Shinisaurus crocodilurus exhibits a dramatic ontogenetic change in scale surface morphology, that is here reported for the first time in any lizard. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160205
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  • 99
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    Histology of the late-stage placentae in the matrotrophic skink Chalcides chalcides (Lacertilia; Scincidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 179-195 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Examination of late-stage placental material of the lizard Chalcides chalcides from the Hubrecht Laboratorium (Utrecht, The Netherlands) reveals several cytological and histological specializations that appear to have been superimposed over a morphological pattern that is typical for squamates. The chorioallantoic placenta is highly vascularized and consists of a single mesometrial placentome and a generalized paraplacentomal region, both of which are epitheliochorial. The placentome is deciduate, and contains deeply interdigitating folds of hypertrophied uterine and chorioallantoic tissue. Chorionic epithelium lining the placentome comprises enlarged, microvilliated cells, a small proportion of which are diplokaryocytes. The placentomal uterine epithelium is not syncytial and consists of enlarged cells bearing microvilli. The yolk sac placenta is a true omphaloplacenta (sensu stricto), being formed by juxtaposition of uterine tissues to an avascular, bilaminar omphalopleure. Epithelium of the omphalopleure is stratified and is hypertrophied into papillae that project into detritus of the uterine lumen. The omphalopleure is separated from the yolk sac proper by a yolk cleft that is not confluent with the exocoelom and is not invaded by the allantois. Neither an omphalallantoic placenta nor a true choriovitelline placenta is present in late gestation. Morphologically, the mature placentae of C. chalcides are among the most specialized to have been described in reptiles, reflecting the substantial maternal-fetal nutrient transfer that occurs in this species. © 1993 Wiley-Liss, Inc.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160206
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  • 100
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    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160301
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