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  • 1
    Electronic Resource
    Electronic Resource
    Microspectrophotometric and enzymatic analyses of fish plasma proteins electrophoretically separated in thin polyacrylamide gels (1974)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 6 (1974), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A system for horizontal, discontinuous electrophoresis in thin sheets of polyacrylamide gel was developed to permit rapid and direct comparison of multiple samples of fish plasmas for population studies. The resulting electropherograms are suitable either for screening for enzyme polymorphisms or for densitometric scanning after gels are stained for total proteins. Each gel sheet (110×90×0.8 mm) can be used for simultaneous separation of 10–15 different samples. Since total voltage and the running time required for successful resolution of fine protein bands are greatly reduced in this system, minimal heating occurs within the gel matrix during electrophoresis. Up to 120 different blood samples (8 gel sheets) can be processed in about 8 h. Gel sheets are routinely stained overnight in Coomassie Brilliant Blue (0.1%, v/v), rinsed several times and stored overnight in 7% acetic acid to complete destaining. Particular gel sectors are then transferred to distilled water and mounted on glass microslides for photography or for densitometric evaluation with a Leitz microspectrophotometer. These procedures have been used to identify characteristic differences in the electrophoretic mobilities of plasma enzymes and albumin fractions from several populations of poeciliid fishes. Observed differences in albumin mobilities (albumin phenotypes) were verified by mixing isoaliquots of test plasmas with plasma samples containing albumins of known mobility. Resultant patterns for albumin bands for such mixed plasmas were indistinguishable from those obtained with plasma samples from the F1 hybrid progeny of parents possessing albumins of characteristically different electrophoretic mobilities. Procedural details for gel casting, electrophoresis and sample evaluation are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1974.tb04521.x
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  • 2
    Electronic Resource
    Electronic Resource
    Significant differential gene duplication without ancestral tetraploidy in a genus of mexican fish (1980)
    Springer
    Cellular and molecular life sciences 36 (1980), S. 927-930 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A comparison of the protein products of 20–25 structural gene loci among the known species of the goodeid fish genusSkiffia suggests that at least 4 loci (16–20%) have undergone species-specific duplications (or, in 1 case, apparent loss) during the evolution of the genus. The species are clearly diploids, and the data therefore indicate that even a large proportion of differentially duplicated loci within a group of related fish species is not critical evidence of common tetraploid ancestry. Differential duplication of structural gene loci may be an important component of the genetic differences that separate congeneric conventional diploid species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01953797
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  • 3
    Electronic Resource
    Electronic Resource
    Cytophotometric and autoradiographic evidence for functional apomixis in a gynogenetic fish, Poecilia formosa and its related, triploid unisexuals (1982)
    Springer
    Histochemistry and cell biology 73 (1982), S. 515-533 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Amounts of DNA in individual Feulgen-stained nuclei from squash preparations of ovaries and testes from wild-caught and laboratory-reared stocks of Poecilia spp. were determined with an integrating microdensitometer. The DNA content of primary spermatocytes (4C) at zygotene, pachytene, or at metaphase I (3.3–3.4 pg) was approximately twice that found in secondary spermatocytes (2C) and four times that found for young spermatids (1C). Rarely, mature sperm were found with 2C DNA amounts. Nuclei from follicular epithelium and oogonia from both bisexual and diploid unisexual fish contained about 1.6–1.7 pg DNA; whereas, the DNA content of primary oocyte nuclei was about 3.5–3.7 pg DNA, indicating that just one cycle of chromosomal replication had occurred in these cells during the period of DNA synthesis before the visible onset of meiotic prophase. Similar results were obtained for triploid unisexuals whose 6C primary oocyte nuclei contained 5.0–5.1 pg DNA, which was twice the DNA content of 3C oogonia and follicular epithelial cells (2.4–2.5 pg DNA). Autoradiographic studies, designed to monitor the incorporation of 3H-thymidine by oogonia and primary oocytes in vivo and in vitro, also showed that there is no additional synthesis of DNA during the course of meiotic prophase in these unisexual fish. Therefore, we conclude that apomixis, not endoreduplication, is the cytological basis of reproduction in Poecilia formosa and its related, triploid biotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493366
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  • 4
    Electronic Resource
    Electronic Resource
    Cytophotometric evidence for the transformation of oocytes into nurse cells inDrosophila melanogaster (1985)
    Springer
    Histochemistry and cell biology 82 (1985), S. 131-134 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A small proportion of ovarian chambers from females homozygous for theotu 7 (forovariantumor) mutation contain an “oocyte” that in its nuclear morphology resembles a nurse cell. Such transformed oocytes also appear in colchicine-poisoned wild type ovaries. Cytophotometric estimates demonstrate that these oocytes have undergone 3–4 additional DNA replications, but that they lag behind the adjacent nurse cells by an average of 1.3 replication cycles. It follows that, under certain circumstances, the definitive oocyte can switch to the nurse cell developmental pathway and therefore that a mechanism normally exists for preventing the further replication of its DNA. In the case ofotu 7, oocytes sometimes restart their endocyclic DNA replications and produce paired, polytene, homologous chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708196
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  • 5
    Electronic Resource
    Electronic Resource
    Cytophotometric studies on cells from the ovaries of otu mutants of Drosophila melanogaster (1984)
    Springer
    Histochemistry and cell biology 81 (1984), S. 105-110 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Amounts of chromosomal DNA were estimated for Feulgen-stained, ovarian cells from flies carrying certain mutant alleles of the otu (ovarian tumor) gene. Epithelial sheath cells and lumen cells were found to contain the diploid (2C) amount of DNA and therefore served as internal, cytophotometric standards. Mitotically active follicle cells over young tumors-from homozygous otu 1 females contained either the 2C or 4C amounts of DNA; whereas, the tumor cell population contained 2C, 4C and 8C nuclei and many intermediate values. Egg chambers also occur in homozygous otu 7 females. Follicle cells above these oocytes undergo a maximum of four cycles of endomitotic DNA replication. The accompanying nurse cells (PNC) contain polytene chromosomes. These undergo a maximum of 12 endonuclear replication cycles. The PNCs show the expected levels of DNA for the first 6 cycles and the fraction failing to replicate during subsequent cycles may be as small as 10%. Lower than expected levels of DNA were detected in PNCs from an otu 1/otu 3 ovary, reflecting roughly 20% underreplication. The latter PNCs may have been interrupted before DNA synthesis was concluded. No simple model of genomic underreplication accounts for the several different patterns of DNA behavior observed for various otu mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00490101
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of DNA content in the nurse and follicle cells from wild type and mutant Drosophila melanogaster by DNA-Feulgen cytophotometry (1985)
    Springer
    Histochemistry and cell biology 82 (1985), S. 233-247 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary DNA replication patterns in the nurse and follicle cells of wild type and a female sterile mutant, fs(1)1304, of Drosophila melanogaster have been studied by DNA-Feulgen cytophotometry, using a cell dispersal technique that allowed the measurement of DNA amounts in individual nuclei from egg chambers of known developmental stages. DNA-Feulgen values associated with various ovarian nuclei from egg chambers at different stages of development were used to assess a base line DNA content for ovarian tissues and to estimate the extent of DNA replication in the nurse cells and follicle cells of growing and mature egg chambers. Our data show that both the nurse and follicle cells undergo multiple cycles of endonuclear DNA replication and that there may be selective amplification as well as underreplication by portions of the genome in these highly polyploid, ovarian cells. Alternative models are proposed to account for the DNA replication patterns observed. Comparisons of DNA-Feulgen levels in wild type ovarian nuclei with those found for the fs(1)1304 mutant and its heterozygote in the balanced stock fs/FM3, show that equivalent DNA levels are present in follicle cell nuclei from all three types of females. Nurse cell nuclei in the homozygous fs stock, however, fail to achieve the same high DNA levels observed in both fs/FM3 and wild type nurse cell nuclei. Although the nuclei of follicle cells in ovaries from fs/fs females appear morphologically like those surrounding egg chambers in wild type ovaries, nurse cell nuclei from mutant females show a more compacted organization of their chromatin than found for nurse cell nuclei from wild type ovaries at similar developmental stages. Our findings suggest that a major effect of the fs(1)1304 mutation may be on the coiling behavior of chromatin and the conformation of DNA-protein moieties in both nurse cell and follicle cell nuclei. These changes in chromatin structure apparently are manifest by perturbations in DNA replication patterns and normal gene function in these biosynthetically active cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501400
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  • 7
    Electronic Resource
    Electronic Resource
    Cytophotometric evidence of variation in genome size of desmognathine salamanders (1986)
    Springer
    Histochemistry and cell biology 85 (1986), S. 185-192 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The amount of DNA per haploid genome, the C-value, is often directly correlated with nuclear and cell volume, but inversely correlated with cell replication rate. Also, rates of cellular growth sometimes appear to be correlated with organismal developmental rates and life history patterns. Among vertebrates, salamanders exhibit the greatest variation in genome size. In the present study we have examined interspecific and intraspecific variation in blood cell DNA levels in the genus Desmognathus, which shows greater variation in life history traits than any other salamander genus. Specimens of Desmognathus quadramaculatus, D. Monticola, D. ochrophaeus and D. wrighti were collected from nature at two localities in the southern Appalachian Mountains. Estimates of genome size in pg of DNA were obtained from blood smears by DNA-Feulgen cytophotometry, using erythrocyte nuclei of Xenopus laevis as an internal reference standard of 6.35 pg DNA per cell. C-values of Desmognathus are the smallest in the order Caudata. Although significant variation in DNA levels was found among the four species, the differences were small, and do not support previously proposed relationships between C-value and life-history variation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00494802
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  • 8
    Electronic Resource
    Electronic Resource
    Patterns of genome size in the copepoda (2000)
    Springer
    Hydrobiologia 417 (2000), S. 43-56 
    Details
    ISSN: 1573-5117
    Keywords: Copepoda ; Harpacticoida ; Cyclopoida ; Calanoida ; genome size ; chromatin diminution ; phylogeny ; cytophotometry ; C-value paradox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adult somatic nuclear DNA contents are reported for eleven cyclopoid species (Megacyclops latipes, Mesocyclops edax, M. longisetus, M. ruttneri, M. leuckarti, M. woutersi, Macrocyclops albidus, Cyclops strenuus, Acanthocyclops robustus, Diothona oculata, Thermocyclops crassus) and for the harpacticoid Tigriopus californicus and range from 0.50 to 4.1 pg DNA per nucleus. These diploid genome sizes are consistent with previously published values for four Cyclops species (0.28–1.8 pg DNA per nucleus), but are strikingly smaller than those reported for marine calanoids (4.32–24.92 pg DNA per nucleus). We discuss three explanations, none of them exclusive of another, to account for the smaller size and range of cyclopoid genome sizes relative to calanoid genome sizes: (1) higher prevalence of chromatin diminution in the Cyclopoida, (2) phylogenetic structure or older age of the Calanoida relative to Cyclopoida and (3) nucleotypic selection that may influence life history variation and fitness. Measurements of genome size were made on Feulgen stained, somatic cell nuclei, using scanning microdensitometry which is well suited to the sparse and heterogeneous populations of copepod nuclei. The importance of measuring large numbers of nuclei per specimen, possible sources of variation associated with cytophotometric measurements, and appropriate use of internal reference standards and stoichiometry of the Feulgen stained nuclei are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003855322358
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