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  • 1
    Electronic Resource
    Electronic Resource
    A smog chamber for studies of the reactions of terpenes and alkanes with ozone and OH (1988)
    Springer
    Journal of atmospheric chemistry 6 (1988), S. 47-59 
    Details
    ISSN: 1573-0662
    Keywords: Smog chamber ; terpenes ; alkanes ; alkenes ; reaction rate constants ; ozone ; OH radical ; photodegradation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The design and performance of a smog chamber for the study of photochemical reactions under simulated environmental conditions is described. The chamber is thermostated for aerosol experiments, and it comprises a gas chromatographic sample enrichment system suitable for monitoring hydrocarbons at the ppbv level. By irradiating NO x /alkane-mixtures rate constants for the reaction of OH radicals with n-alkanes are determined from n-pentane to n-hexadecane to be (k±2σ)/10−12 cm3 s−1=4.29±0.16, 6.2±0.6, 7.52 (reference value), 8.8±0.3, 10.2±0.3, 11.7±0.4, 13.7±0.3, 15.1±0.5, 17.5±0.6, 19.3±0.7, 22.3±1.0, and 25.0±1.3, respectively at 312 K. Rate constants, (k±2σ)/10−17 cm3 s−1, for the reaction of ozone with trans-2-butene (21.2±1.0), cis-3-methylpentene-(2) (47.2±1.7), cyclopentene (62.4±3.5), cyclohexene (7.8±0.5), cycloheptene (28.3±1.5), α-pinene (8.6±1.3), and β-pinene (1.4±0.2) are determined in the dark at 297 K using cis-2-butene (13.0) as reference standard.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048331
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro model systems of carcinogenesis: Interaction between c-Ha-ras oncogene and immortalized cells (1988)
    Springer
    Bulletin of experimental biology and medicine 105 (1988), S. 389-392 
    Details
    ISSN: 1573-8221
    Keywords: immortalization ; oncogenes ; transfection ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00835760
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  • 3
    Electronic Resource
    Electronic Resource
    Transformation of zinc in soils under submerged condition and its relation with zinc nutrition of rice (1988)
    Springer
    Plant and soil 106 (1988), S. 121-126 
    Details
    ISSN: 1573-5036
    Keywords: organic matter ; rice ; submergence ; transformation ; zinc fraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory and greenhouse experiments were conducted with two soilsviz., laterite and alluvial to study the transformation of applied Zn in soil fractions under submerged condition in the presence and absence of added organic matter and its relationship with Zn nutrition of rice plants. The results showed that application of organic matter caused a decrease in the concentration of Zn in shoot and root of rice plants and helped in translocating the element from root to shoot. The per cent utilization of applied Zn by plants was also found to increase by the application of organic matter. The transformation of applied Zn in different fractions in soils showed that a major portion (53.6–72.6%) of it found its way to mineral fractions leaving only 1.0–3.3, 6.6–18.9, 11.0–21.6 and 2.3–8.8% of the applied amounts in water soluble plus exchangeable, organic complexed, amorphous sesquioxides and crystalline sesquioxides bound fractions respectively. Application of organic matter favoured such transformation of applied Zn into these fractions except the mineral and crystalline sesquioxides bound ones. Simple correlation and multiple regression analyses between applied Zn in different soil fractions and fertilizer Zn content in plants showed that organic matter application increased the predictability of fertilizer Zn content in plants which has been attributed to the higher per cent recovery of applied Zn in plant available fractions in soils in presence of added organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371203
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  • 4
    Electronic Resource
    Electronic Resource
    Investigation into chromosomal stability of in-vitro growing cells from a transformed monosomic addition plant of beet (1988)
    Springer
    Euphytica 39 (1988), S. 177-184 
    Details
    ISSN: 1573-5060
    Keywords: Beta vulgaris ; Beta procumbens ; Agrobacterium tumefaciens ; monosomic additions ; transformation ; chromosomal stability ; electrophoresis ; isozyme patterns ; in-vitro culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Crown galls were obtained from a monosomic addition plant of beet, carrying an extra chromosome of Beta procumbens, after transformation with a wild-type Agrobacterium tumefaciens strain. Analysis of peroxidase and esterase patterns obtained after cellulose acetate gel electrophoresis and iso-electric focusing respectively, gave evidence that no preferential loss of the alien chromosome on repeated subculture in-vitro from the crown galls occurred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043381
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  • 5
    Electronic Resource
    Electronic Resource
    Transformation and regeneration in sugar beet (Beta vulgaris L.) induced by ‘shooter’ mutants of Agrobacterium tumefaciens (1988)
    Springer
    Euphytica 39 (1988), S. 185-194 
    Details
    ISSN: 1573-5060
    Keywords: Agrobacterium tumefaciens ; Beta vulgaris ; sugar beet ; regeneration ; shooter mutants ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Beta vulgaris plants were found to be susceptible to Agrobacterium tumefaciens strains carrying octopine Ti-plasmids after wounding of GA3 elongated stems or of hypocotyls. Tumors could be isolated and cultured aseptically. The tumor marker, octopine synthase (Ocs) activity, was present demonstrating the applicability of the Agrobacterium system for transfer of genetic information. For the production of transgenic plants two procedures were tested: inoculation of explants derived from cotyledons and hypocotyls of two weeks old seedlings and a leaf-disc procedure. The first method yielded both octopine positive calli as well as shoot regeneration on the six genotypes tested. In most cases, regeneration occurred from pre-existing, non-transformed meristems. The presence of Ocs activity could not be demonstrated in these shoots, although in one case octopine positive callus was formed at the base of the shoot, suggesting a chimeric structure of the plantlet or T-DNA genes, which were silent within the shoot and became active again in proliferating callus. The leaf-disc method did not give rise to direct or indirect regeneration, but transformed callus proliferated on the leaf edges. Optimal transformation frequencies were dependent on B. vulgaris genotype and Agrobacterium strain. The use of Agrobacterium shooter mutants or strains carrying an isolated cytokinin gene in order to influence endogenous phytohormone ratios did not result in the formation of shoots nor did it increase levels of regeneration in the first method. Further optimization is in order and in progress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043382
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  • 6
    Electronic Resource
    Electronic Resource
    Tissue-specific expression of a pea legumin gene in seeds of Nicotiana plumbaginifolia (1988)
    Springer
    Plant molecular biology 10 (1988), S. 203-214 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium ; gene expression ; legumin (Pisum) ; Nicotiana ; seed storage protein ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 3.4-kilobase genomic DNA fragment from Pisum sativum L. containing the LegA gene, which encodes a major legumin storage protein, was transferred to Nicotiana plumbaginifolia using an Agrobacterium tumefaciens strain containing the Bin 19 binary vector system. Northern hybridisation analysis of legA-transformed plants demonstrated that legumin-specific RNA was present in developing seeds but not in developing leaves. Legumin protein was immunologically detected in the mature seeds of legA-transformed plants, and was present as the correct-size protein composed of disulphide-bonded polypeptides. It is concluded that the transferred pea genomic fragment contains all the information necessary for seed-specific expression of the legA gene, and for correct processing of the primary transcript and the precursor legumin protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027397
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  • 7
    Electronic Resource
    Electronic Resource
    Regeneration of flax plants transformed by Agrobacterium rhizogenes (1988)
    Springer
    Plant molecular biology 11 (1988), S. 551-559 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium rhizogenes ; Agrobacterium tumefaciens ; Linum usitatissimum ; plant regeneration ; Ri plasmid ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regeneration of flax (Linum usitatissimum) following transformation by either Agrobacterium tumefaciens carrying a disarmed Ti-plasmid vector, or Agrobacterium rhizogenes carrying an unmodified Ri plasmid, was examined. Hypocotyl and cotyledon explants inoculated with A. tumefaciens formed transformed callus, but did not regenerate transformed shoots either directly or via callus. However, cotyledon explants inoculated with A. rhizogenes formed transformed roots which did regenerate transformed shoots. Ri T-DNA encoded opines were detected in the transformed plantlets and Southern hybridization analysis confirmed the presence of T-DNA from the Ri plasmid in their DNA. Transformed plantlets had curled leaves, short internodes and some had a more developed root system characterized by plagiotropic behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017455
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  • 8
    Electronic Resource
    Electronic Resource
    Conformational effects of the substitution of ARG for GLY 13 in theras oncogene-encoded P21 protein (1988)
    Springer
    The protein journal 7 (1988), S. 349-354 
    Details
    ISSN: 1573-4943
    Keywords: conformational energy ; amino acid substitution ; position 13 ; P21 protein ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the substitution of Arg for Gly 13 on the structure of the transforming region decapeptide (Leu 6-Gly 15) of the ras oncogene encoded P21 protein has been investigated using conformational energy analysis. A human malignancy has been identified that contains a ras gene with a single mutation in the thirteenth codon such that the encoded protein would have Arg substituted for Gly at this position, and transfection of cells in culture with this gene results in malignant transformation. Conformational analysis demonstrates that the Arg 13 decapeptide adopts a conformation identical to that for other peptides with substitutions at position 13 (Asp 13, Val 13) from transforming proteins that is distinctively different from that for peptides (Gly 13, Ser 13) from normal, nontransforming proteins. This is found to be an indirect effect resulting from changes in the conformation of Gly 12 produced by substitutions at position 13. These results are consistent with recent analysis of crystallographic data of proteins on conformational preferences for glycine in tripeptide sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01024884
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  • 9
    Electronic Resource
    Electronic Resource
    Regulation of cell division and malignant transformation (1988)
    Springer
    Bioscience reports 8 (1988), S. 519-529 
    Details
    ISSN: 1573-4935
    Keywords: cell division ; malignancy ; transformation ; nutrient uptake ; resting state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The problem of regulation of cell division is essentially a problem of understanding regulation of transition from the resting state of a cell to the dividing state and vice versa. In malignancy the ability to revert back to a normal resting state is impaired. A model is presented which attempts to explain the control of the above transitions through control of uptake of essential nutrients by a transport-inhibitory protein. Experimental evidence in favour of the model is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01117330
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  • 10
    Electronic Resource
    Electronic Resource
    Binding, uptake and expression of foreign DNA by cyanobacteria and isolated etioplasts (1988)
    Springer
    Photosynthesis research 19 (1988), S. 23-37 
    Details
    ISSN: 1573-5079
    Keywords: binding ; uptake ; transformation ; DNA ; cyanobacteria ; etioplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Discoveries of the uptake and expression of various Escherichia coli plasmids by the cyanobacterium Anacystis nidulans and isolated cumber etioplasts are reviewed. In particular, the binding and uptake of nick-translated 32P-labeled plasmids and the expression of genes in the native plasmids are considered. Permeaplasts of A. nidulans 6301 and isolated EDTA-washed cucumber etioplasts exhibit binding and uptake of DNA that is unaffected by uncouplers of photophosphorylation or by dissipators of transmembrane proton graident. ATP inhibits both binding and udptake by permeaplasts or EDTA-washed etioplasts but the analog AMP-PNP (non-hydrolzable) is noninhibitory. With permeaplasts there is no effect of 20 mM Mg2+ (in the light) upon intake, whereas with EDTA-washed etioplasts, Mg2+ at the same concentration inhibits uptake as does 20 mM Ca2+. The transformation of A. nidulans 6301 to ampicillin-resistance by the plasmid pBR322 is much enhanced in permeaplasts. Indeed extracts of transformed cells catalyze the hydrolosis of the β-lactam nitrocefin. Transfromation of A. nidulans to antibiotic resistance may also be achieved with the plasmids pHUB4 and pCH1. The effect of light on transformation of A. nidulans 6301 differs with different plasmids. In pBR322 transformants the expression of ribulose bisphosphate carboxylase-oxygenase (RuBisCO) is markedly elevated. In these transformants, the foreign plasmid replicates by a pathway involving chromosomal integration and dissociation. The plasmid pCS75, a derivative of pUC9 (and therefore of pBR322) containing a Pst1 insert carrying genes for the large and small (S) subunits of RuBisCO from A. nidulans, is taken up and expressed in EDTA-washed cucumber cotyledon etioplasts. Expression is evidenced by the hydrolysis of nitrocefin and immunoprecipitation of labeled S subunits of RuBisCO (utilizing etioplasts which have been labeled with 35S-methionine after incubation with pCS75). The plasmid pUC9-CM carrying a cat gene is also expressed in cucumber etioplasts in a manner that demonstrates dependence both on the duration of etioplast washing by EDTA and plasmid concentration. Translation (as measured by 35S-methionine incorporation) by EDTA-washed etioplasts increases with cotyledon greening. However the enhancement of translation by prior incubation of EDTA-washed plastids with pCS75 decreases to zero during 24hr of cotyledon greening. Results suggest that the expression of foreign DNA in plastids may depend critically upon their developmental state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00114567
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  • 11
    Electronic Resource
    Electronic Resource
    Inhibition of gene expression in transformed plants by antisense RNA (1988)
    Springer
    Plant molecular biology 11 (1988), S. 301-310 
    Details
    ISSN: 1573-5028
    Keywords: plants ; antisense ; suppression ; nopaline synthase ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report the successful suppression of nopaline synthase (EC 1.5.1.19) enzymatic activity in the leaves of tobacco plants via the overproduction of RNAs complementary to the nopaline synthase (nos) mRNA. Several different regions of the nos gene were fused, in antisense orientation, to the promoter from a strongly expressed petunia chlorophyll a/b-binding protein gene. These constructions were directly introduced into a tobacco line which contained a single copy of the wild-type nos gene and transgenic plants were regenerated. The degree of nopaline synthase suppression in the leaves of the double transformants ranged up to 85% and was dependent on the particular region of the nos gene present in the antisense RNA. The most effective nos antisense sequences were derived from the 3′ half of the nos gene transcript. In addition, we report a new sensitive method for the detection and quantitation of nopaline synthase activity in crude plant extracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027387
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  • 12
    Electronic Resource
    Electronic Resource
    Homogeneity analysis withk sets of variables: An alternating least squares method with optimal scaling features (1988)
    Springer
    Psychometrika 53 (1988), S. 177-197 
    Details
    ISSN: 1860-0980
    Keywords: homogeneity analysis ; correspondence analysis ; optimal scaling ; transformation ; alternating least squares ; canonical correlation analysis ; principal component analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract Homogeneity analysis, or multiple correspondence analysis, is usually applied tok separate variables. In this paper we apply it to sets of variables by using sums within sets. The resulting technique is called OVERALS. It uses the notion of optimal scaling, with transformations that can be multiple or single. The single transformations consist of three types: nominal, ordinal, and numerical. The corresponding OVERALS computer program minimizes a least squares loss function by using an alternating least squares algorithm. Many existing linear and nonlinear multivariate analysis techniques are shown to be special cases of OVERALS. An application to data from an epidemiological survey is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02294131
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  • 13
    Electronic Resource
    Electronic Resource
    Multivariate analysis with linearizable regressions (1988)
    Springer
    Psychometrika 53 (1988), S. 437-454 
    Details
    ISSN: 1860-0980
    Keywords: multivariate analysis ; optimal scaling ; correspondence analysis ; structural models ; simultaneous equations ; factor analysis ; LISREL ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract We study the class of multivariate distributions in which all bivariate regressions can be linearized by separate transformation of each of the variables. This class seems more realistic than the multivariate normal or the elliptical distributions, and at the same time its study allows us to combine the results from multivariate analysis with optimal scaling and classical multivariate analysis. In particular a two-stage procedure which first scales the variables optimally, and then fits a simultaneous equations model, is studied in detail and is shown to have some desirable properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02294399
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  • 14
    Electronic Resource
    Electronic Resource
    Monoclonal antibodies directed against rat liver epithelial cell lines selectively recognize bile duct epithelium in livers of adult rats (1988)
    Springer
    Cell biology and toxicology 4 (1988), S. 379-392 
    Details
    ISSN: 1573-6822
    Keywords: hepatocytes ; hepatocarcinogenesis ; immunohistochemistry ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Monoclonal antibodies directed against antigens on rat liver epithelial cell lines were prepared. Three antibodies, 4C3, 19C6, and 3C2, recognized surface antigens present (although in different quantities) on eight epithelial cell lines tested, irrespective of whether they were normal or transformed. For MAb 3C2, the primary antigen common to all but one cell line showed a Mr of 135 kD. In paraffin sections of liver tissue, two antibodies, 40 and 19C6, reacted exclusively with bile duct epithelium, whereas the MAb 3C2 additionally reacted with sinusoidal endothelium and the endothelium of the portal venules. In sections of livers from rats exposed to diethylnitrosamine, the MAb 19C6 selectively stained bile duct-like structures in cholangiomas, while other preneoplastic and neoplastic lesions were not stained. These results demonstrate that the monoclonal antibodies obtained may prove useful for investigating cell lineages related to propagable liver epithelial cell lines and suggest that these cells may be derived from terminal bile ductular cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117767
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  • 15
    Electronic Resource
    Electronic Resource
    Vanadate-treated baby hamster kidney fibroblasts show cytoskeleton and adhesion patterns similar to their rous sarcoma virus-transformed counterparts (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 37 (1988), S. 151-159 
    Details
    ISSN: 0730-2312
    Keywords: vanadate ; phosphotyrosine ; transformation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Rous sarcoma virus-trans formed baby hamster kidney fibroblasts (RSV/B4-BHK) adhere to a fibronectin-coated substratum by means of dot-like adhesion sites called podosomes in view of their shape and function as cellular feet (Tarone et al.: Exp Cell Res 159:141, 1985). Podosomes concentrate tyrosine-phosphorylated proteins, including pp60v-src, and appear in many cells transformed by oncogenes coding for tyrosine kinases. In this paper we used orthovanadate, an inhibitor of phosphotyrosine phosphatases, in order to increase the cellular concentration of phosphotyrosine and to study whether this treatment induced the cytoskeleton remodeling leading to the formation of podosomes. Indeed, orthovanadate (10-100 μM) induced in a time-and dose-dependent manner the redistribution of F-actin and the formation of podosomes in BHK cells. Cytoskeleton remodeling occurred along with a marked increase of tyrosine phosphorylatcd proteins. The vanadate effect on the cytoskeletal phenotype was enhanced by the simultaneous treatment of cells with a phorbol ester. Under the latter conditions almost all BHK cells showed podosomes. The vanadate effect was reversible insofar as podosomes and tyrosine-phosphorylated proteins disappeared. Then, vanadate treatment of normal cells induced the cascade of events leading to the cytoskeletal changes typical of transformation and suggested that the transformed cytoskeletal phenotype may he primarily induced by the tyrosine phosphorylation of unknown target(s) operated by endogenous kinases.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240370203
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  • 16
    Electronic Resource
    Electronic Resource
    Comparison of N-acetylglucosaminyltransferase V activities in Rous sarcoma-transformed baby hamster kidney (RS-BHK) and BHK cells (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 37 (1988), S. 225-231 
    Details
    ISSN: 0730-2312
    Keywords: glycosyltransferase ; cell surface ; transformation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Recent studies have desmonstrated that Rous sarcoma virus-transformed baby hamster kidney (RS-BHK) cells express twofold higher levels of those N-linked oligosac-charides that contain the sequence [GlcNAc-β(1,6)Man (1,6)] compared to nontrans-formed parental BHK cells (Pierce and Arango, J. Biol. Chem. 261, 10772 [1986]). We have investigated in RS-BHK and BHK cells the activity of UDP-GlcNAc:α-D-mannoside β(l,6)N-acetylglucosaminyltransferase V, the enzyme that begins the synthesis of the sequence that is increased in the RS-BHK cells. We have measured GnT V activity using UDP- [3H]- GlcNAc and a synthetic oligosaccharide acceptor, GlcNAcβ(1,2)Man α(1,6)Manβ-O- (Ch2)8COOCH3, separating the radioactive product by a newly devised reverse-phase chromatographic technique. Assayed under optimal conditions, the specific activity of GnT V is about fourfold higher in RS-BHK sonicates than in BHK sonicates, suggesting that this increase in activity may be the primary mechanism that causes the increase in [GlcNAcβ(1,6) Man] sequences in the RS-BHK cells. The apparent Km, values of the enzymes in RS-BHK and BHK cell sonicates for UDP-GIcNAc and the synthetic acceptor are similar, as are the pH optima. These results suggest that the increase in GnT V-specific activity in RS-BHK cells is not caused by the presence in these cells of a GnT V with markedly different kinetic properties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240370209
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  • 17
    Electronic Resource
    Electronic Resource
    Cell surface heparan sulfate proteoglycan and the neoplastic phenotype (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 37 (1988), S. 61-78 
    Details
    ISSN: 0730-2312
    Keywords: heparan sulfate ; transformation ; cell surface proteoglycans ; growth control ; cancer glycosaminoglycans ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cell surface proteoglycans are strategically positioned to regulate interactions between cells and their surrounding environment. Such interactions play key roles in several biological processes, such as cell recognition, adhesion, migration, and growth. These biological functions are in turn necessary for the maintenance of differentiated phenotype and for normal and neoplastic development. There is ample evidence that a special type of proteoglycan bearing heparan sulfate side chains is localized at the cell surface in a variety of epithelial and mesenchymal cells. This molecule exhibits selective patterns of reactivity with various constituents of the extracellular matrix and plasma membrane, and can act as growth modulator or as a receptor. Certainly, during cell division, membrane constituents undergo profound rearrangement, and proteoglycans may be intimately involved in such processes. The present work will focus on recent advances in our understanding of these complex macromolecules and will attempt to elucidate the biosynthesis, the structural diversity, the modes of cell surface association, and the turnover of heparan sulfate proteoglycans in various cell systems. It will then review the multiple proposed roles of this molecule, with particular emphasis on the binding properties and the interactions with various intracellular and extracellular elements. Finally, it will focus on the alterations associated with the neoplastic phenotype and will discuss the possible consequences that heparan sulfate may have on the growth of normal and transformed cells.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240370107
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  • 18
    Electronic Resource
    Electronic Resource
    Arsenic compounds in marine and terrestrial organisms: Analytical, chemical and biochemical aspects (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 303-307 
    Details
    ISSN: 0268-2605
    Keywords: Arsenic ; arsenic compounds ; transformation ; determination ; biological significance ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arsenic has a reputation as a poison, because arsenic trioxide was used during medieval times as an agent for murder. Lingering memories of these events make any arsenic-containing material suspect. Toxicity is a property of a specific compound and varies with the composition and structure of compounds. Developments in analytical methodology made it possible not only to determine total arsenic in a variety of matrices but also arsenic compounds. Knowledge about the arsenic cycle in marine systems has expanded considerably during the past decade. The marine arsenic cycle appears to be more complex than the cycle in the terrestrial environment. More attention must be given to the minor arsenic-containing compounds detected in organisms and experiments should be undertaken that provide information about the biochemical pathways used for the transformation of arsenic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590020405
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  • 19
    Electronic Resource
    Electronic Resource
    The cyclic nucleotide phosphodiesterase of Dictyostelium discoideum: The structure of the gene and its regulation and role in development (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 267-278 
    Details
    ISSN: 0192-253X
    Keywords: transformation ; gene structure ; cAMP ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cyclic nucleotide phosphodiesterase (phosphodiesterase) of Dictyostelium discoideum plays an essential role in development by hydrolyzing the cAMP used as a chemoattractant by aggregating cells. We have studied the biochemistry of the phosphodiesterase and a functionally related protein, the phosphodiesterase inhibitor protein, and have cloned the cognate genes. A 1.8-kb and a 2.2-kb mRNA are transcribed from the singlephosphodiesterase gene. The 2.2-kb mRNA comprises the majority of the phosphodiesterase mRNA found in differentiating cells and is transcribed only during development from a promoter at least 2.5 kb upstream of the translational start site. The 1.8-kb phosphodiesterase mRNA is detected at all stages of growth and development, is present at lower levels than the developmentally induced mRNA, and is transcribed from a site proximal to the protein-coding region. The phosphodiesterase gene contains a minimum of three exons, and a 2.3-kb intron, the longest yet reported for this organism. We have shown that the pds A. gene and fourfgd genes affect, the accumulation of the phosphodiesterase mRNAs, and we believe that these loci represent a significant portion of the genes regulating expression of the phosphodiesterase. The phosphodiesterase gene was introduced into cells by transformation and used as a tool to explore the effects of cAMP on the terminal stages of development. In cells expressing high levels of phosphodiesterase activity, final morphogenesis cannot be completed, and differentiated spore and stalk cells do not form. We interpret these results to support the hypothesis that cAMP plays an essential role in organizing cell movements in late development as well as in controlling the aggregation of cells in the initial phase of the developmental program.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090409
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  • 20
    Electronic Resource
    Electronic Resource
    Nuclear plasmids in the Dictyostelium slime molds (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 495-504 
    Details
    ISSN: 0192-253X
    Keywords: transformation ; extrachromosomal DNAs ; eukaryotic plasmids ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cellular slime molds are one of only three types of eukaryotes known to contain circular nuclear plasmids. Unlike the 2-μm circle in Saccharomyces, different strains of Dictyostelium can carry different, nonhomologous plasmids. Covalently closed, circular DNA plasmids have been identified in D. discoideum, D. mucoroides, D. giganteum, and D. purpureum. These plasmids range in size from 1.3-27 kb and in copy number from 50-300 molecules per cell. Plasmids have been identified in approximately one-fifth of all isolates examined. The organization of their DNA in nucleosomes establishes their presence in the nucleus. We have successfully cotransformed endogenous Dictyostelium plasmids into D. discoideum using the G418 resistance shuttle vector B10S. Transformants carrying D. discoideum plasmids are recovered at much higher frequency than those carrying plasmids from the other Dictyostelium species. We have constructed recombinant plasmids based on the D. discoideum plasmid Ddp2 and the G418 resistance gene. With these extrachromosomal vectors, transformed cells are recovered at frequencies of up to 10-4 per input cell, the vectors are stably maintained at high copy number in the absence of selection, and the vectors can be used to introduce foreign DNA sequences into D. discoideum cells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090426
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