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11.
SV40 immortalizes myogenic cells: DNA synthesis and mitosis in differentiating myotubes 总被引:8,自引:0,他引:8
Sonia Lujvidin Ora Fuchs Uri Nudel David Yaffe 《Differentiation; research in biological diversity》1990,43(3):192-203
Primary skeletal muscle myoblasts have a limited proliferative capacity in cell culture and cease to proliferate after several passages. We examined the effects of several oncogenes on the immortalization and differentiation of primary cultures of rat skeletal muscle myoblasts. Retroviruses containing a SV40 large T antigen (LT) gene very efficiently immortalize myogenic cells. The immortalized cell lines retain a very high differentiation capacity and form, in the appropriate culture conditions, a very dense network of muscle fibers. As in primary culture, cell fusion is associated with the synthesis of large amounts of muscle-specific proteins. However, unlike normal myoblasts (and previously established myogenic cell lines), nuclei in the multinucleated fibers of SV40-immortalized cells synthesize DNA and enter mitosis. Thus, withdrawal from DNA synthesis is not obligatory for cell fusion and biochemical differentiation. Using a retrovirus coding for a temperature-sensitive SV40 LT, myogenic cell lines were produced in which the SV40 LT could be inactivated by a shift from 33 degrees C to 39 degrees C. The inactivation of LT induced massive cell fusion and synthesis of muscle proteins. The nuclei in those fibers did not synthesize DNA, nor did they undergo mitosis. This approach enabled the reproducible establishment of myogenic cell lines from very small populations of myoblasts or single primary myogenic clones. Activated p53 also readily immortalized cells in primary muscle cultures, however the cells of eight out of the nine cell lines isolated had a fibroblastic morphology and could not be induced to form multinucleated fibers. 相似文献
12.
Sucrose was found to have a modulating effect on the morphogenesisof Anagallis arvensis L. leaves cultured in a Murashige-Skoogmedium. Root formation and growth seem to be more independentthan other morphogenetic expressions. Roots formed without exogenoussugars at 25°C but sucrose seemed to be necessary at 32and 35°C. Sucrose at 3% improved shoot formation at 25°Cand had an inhibitory effect at 6%concentration and 35°C.Shoot growth (internode length) is inhibited by sucrose concentrationshigher than 3%. Sucrose could also replace light irradiancein regulating shoot and leaf growth. A higher sucrose concentration,than that required for roots and shoots formation, is necessaryfor flower and fruit formation, but sucrose could not replacethe photoperiod requirement for flowering in culture medium. (Received June 17, 1985; Accepted December 24, 1985) 相似文献
13.
Wolfgang Löscher Gerhard Böhme Frank Müller Sonia Pagliusi 《Journal of neurochemistry》1985,45(3):879-889
A procedure is described for the rapid preparation of nerve ending particles (synaptosomes) from 11 regions of one rat brain. The synaptosomal fractions have been characterized by electron microscopy and determination of four marker enzymes, i.e., glutamate decarboxylase (GAD), acetylcholinesterase, succinate dehydrogenase, and glycerol 3-phosphate dehydrogenase. Comparison with a much lengthier standard (Ficoll-sucrose) preparation showed that the synaptosomal yield of the new procedure was substantially better as judged by both morphological evaluation and protein recovery. The improved synaptosome preparation was used for determination of regional gamma-aminobutyric acid (GABA) levels in synaptosomal fractions. The postmortem increase in GABA level during removal and dissection of brain tissue and homogenization and fractionation procedures could be minimized by rapid processing of the tissue at low temperatures and inclusion of the GAD inhibitor 3-mercaptopropionic acid (3-MP; 1 mM) in the homogenizing medium. The addition of GABA (0.2 mM) to the homogenizing medium did not alter the GABA levels in the synaptosomes, indicating that no significant redistribution of GABA occurred during subcellular fractionation in sodium-free media. Synaptosomal GABA levels determined in the 11 rat brain areas showed the same regional distribution as the GABA-synthesizing enzyme GAD. On the basis of these findings, it was suggested that the synaptosome preparation could be used to evaluate the in vivo effects of drugs on nerve terminal GABA. Treatment of rats with a convulsant dose of 3-MP (50 mg/kg i.p.) 3 min before decapitation significantly lowered synaptosomal GABA levels in olfactory bulb, hippocampus, thalamus, tectum, and cerebellum. The 3-MP-induced seizures and reduction of GABA levels could be prevented by administration of valproic acid (200 mg/kg i.p.) 15 min before the 3-MP injection. The data indicate that the improved synaptosome preparation offers a convenient method of preparing highly purified synaptosomes from a large number of small tissue samples and can provide useful information on the in vivo effects of drugs on regional GABA levels in nerve terminals. 相似文献
14.
Teresa de Sa E Melo Patrice Morlière Sonia Goldstein René Santus Louis Dubertret Dominique Lagrange 《Biochemical and biophysical research communications》1984,120(2):670-676
5-methoxypsoralen (5-MOP) binds to human serum low density lipoproteins (LDL) according to a two-step process. Scatchard analysis of the first step yields K = 1.4 × 105 M?1 and 4 binding sites. It involves the LDL apoprotein. The second step corresponds to a solubilization, in the lipidic core, of ? 45 molecules of 5MOP per LDL molecule. It is accompanied by a large blue shift of the 5MOP fluorescence. The ability of LDL to bind 5MOP and to carry it into various cells may explain some biological effects sometimes encountered during PUVA therapy. 相似文献
15.
This study was performed to determine the biological activity in mice of eight species of Solidago (goldenrod) and to determine some of the chemical groups present in these species. Biologically active substances were present in all of the species tested. Tests of six species were positive for alkaloids. All but one of the species contained demonstrable saponins. All of the species contained tannins, whereas six or seven species were positive for flavonoids. Quaternary bases were not found in any of the species tested. A comparison of the biological activity in mice of these species of Solidago, extracts of which were injected intraperitoneally, showed their descending order of activity to be: (1)S. flexicaulis L., (2)S. hispida Muhl., (3)S. juncea Ait., (4)S. serotina Ait., (5)S. canadensis L., (6)S. rugosa Ait., (7)S. uliginosa Nutt., and (8)S. squarrosa Muhl. 相似文献
16.
17.
Sonia R. Virdee Godfrey M. Hewitt 《Evolution; international journal of organic evolution》1994,48(2):392-407
Two subspecies of the grasshopper Chorthippus parallelus meet in the Pyrenees forming a hybrid zone several kilometers wide. Crosses between the two pure taxa result in sterile male offspring and normal females (i.e., Haldane's rule applies). However, no such dysfunction has been detected in hybrid males collected through the center of the hybrid zone. By assessing the level of dysfunction in the offspring of reciprocal crosses, it was possible to map clines for the genes responsible for dysfunction through the zone. This analysis shows that there is no abrupt transition between incompatible genomes in the field. Crosses were also made between females collected from a transect spanning the hybrid zone and pure males of both subspecies. This reveals noncoincident clines for dysfunction near the center of the hybrid zone such that the dysfunction expressed in the offspring of these crosses is less than expected from simple models. More complex models involving interaction among genes must be invoked. Also, the possibility exists that since the postglacial contact of these two grasshopper taxa, hybrid dysfunction has become ameliorated by the evolution of modifiers. This hybrid zone is thought to be a tension zone, maintained by a balance between selection against hybrid genotypes and dispersal into the zone center. The lessening of hybrid disadvantage over time through the breakdown of epistatic interactions by recombination or through modification could account for the general lack of dysfunction in field collected hybrids today. 相似文献
18.
Beatriz Ernestina Cabilio Guth Eliana Gonalves Aguiar Patricia Marie Griffin Sonia Regina Testa da Silva Ramos Tnia Aparecida Tardelli Gomes 《Microbiology and immunology》1994,38(9):695-701
Fifty-eight enterotoxigenic Escherichia coli (ETEC) strains, isolated from children with and without diarrhea in Sao Paulo, were examined for the presence of colonization factor antigens (CFAs) and their ability to adhere to HeLa cells. Antisera to CFA/I, the coli surface (CS) antigens CS1CS3, CS2CS3, and CS2 of CFA/II, CFA/III, and CS5CS6 and CS6 of CFA/IV were used. CFAs were identified in 43% of the ETEC strains: 40% of the strains with CFAs harbored CFA/I, 24% carried CFA/II (CS1CS3), 24% carried CFA/IV (CS6), and 12% carried CFA/IV (CS5CS6). CFAs occurred mainly among ETEC strains producing only heat-stable (ST-I) enterotoxin and in strains also producing heat-labile toxin (LT-I). No ETEC strains tested expressed CFA/III. A marked change in serotypes of ST-I-producing strains was found in Sao Paulo between 1979 and 1990. Adherence to HeLa cells was detected in 14% of the ETEC strains. All of them had a diffuse adherence pattern and produced only ST-I, and 88% carried CS6 antigen. 相似文献
19.
Josef Maier Karin Schott Thomas Werner Adelbert Bacher Irmgard Ziegler 《Experimental cell research》1993,204(2)
Fragments of cDNA coding for rat, murine, and human sepiapterin reductase (SR) were amplified by PCR via primer positioning close to the reported 3′-end of the coding region in the rat enzyme. They were sequenced and used as probes for mRNA detection. Northern blot analysis detected two mRNA species for SR. Their sizes were 1.3 and 2.1 kb for rat, 1.3 and 2.3 kb for mouse, and 1.6 and 2.1 kb for human cell lines. Comparison of rat cell lines and rat tissues indicated that in tissues only the 1.3-kb species is present. Washing of the Northern blots under different stringency conditions indicated a more stable interaction of the 1.3-kb mRNA species with the cDNA probe as compared to the 2.3-kb species. The 1.3-kb species corresponds to the reported 28.2-kDa molecular mass of rat SR monomer. SR mRNA expression is absent in the human NK-like cell line YT and in the murine erythroleukemia subclone B8/3, which both lack SR activity. Moreover, the relative mRNA expression correlates with the enzymatic activities of different cell lines within the same species. This indicates that SR activity is regulated by its steady state mRNA levels. 相似文献
20.
Niche breadth explains the range size of European-centred butterflies,but dispersal ability does not
Johannes Hausharter Sonia Rashid Johannes Wessely Patrick Strutzenberger Dietmar Moser Andreas Gattringer Konrad Fiedler Karl Hülber Stefan Dullinger 《Global Ecology and Biogeography》2023,32(9):1535-1548