Effects of FSH on acidic nuclear protein synthesis in cultured pig Sertoli cells.

We studied the effect of FHS on nuclear protein synthesis by a primary culture of immature porcine Sertoli cells. The cells were cultured in a chemically defined medium and treated with FSH (50 ng/ml) for various periods (4, 8, 25 and 64 h). About 65 spots (pHi less than 8) were identified by two-dimensional polyacrylamide gel electrophoresis of the radiolabelled nuclear proteins. After 25 h of FSH treatment, we observed an increase of 5 proteins, a slight decrease of two and a disappearance of one. For the short periods of FSH treatment (4 and 8 h), no effect of FHS on nuclear protein synthesis was observed. After 64 h of FSH treatment (4 and 8 h), no effect of FHS on nuclear protein synthesis was observed. After 64 h of FSH treatment, the synthesis of all nuclear proteins appears to be decreased.

The effects of FSH and of testosterone on the completion of meiosis and the very early steps of spermiogenesis of the rat: an in vitro study.

The role of FSH and of testosterone in spermatogenesis has been a matter of controversy. In the present study, we addressed the involvement of these hormones in the regulation of the completion of meiosis of male rats under in vitro conditions. In the first series of experiments, middle/late pachytene spermatocytes were cocultured with Sertoli cells for 2 weeks in the absence or presence of FSH and/or testosterone. Treatment with both FSH and testosterone reduced slightly the percentage of apoptotic germinal cells in the cultures. Moreover, the number of round spermatids formed in vitro was enhanced by FSH or testosterone when compared with control cultures. Neither hormone influenced the half-life of round spermatids under the present culture conditions. The amounts of TP1 mRNAs in FSH- or FSH plus testosterone-treated cultures were higher than those of controls. In another series of experiments, round spermatids were incubated for 24 h in media conditioned by Sertoli cells cultured in the absence or presence of FSH and/or testosterone. TP1 mRNA contents of round spermatids incubated in media from Sertoli cells cultured in the presence of FSH and/or testosterone were two- to threefold higher than those of spermatids incubated in media from Sertoli cells cultured without hormones. These results indicate that FSH and testosterone have positive and somewhat overlapping effects on the meiotic divisions and the post-meiotic expression of a germ cell-specific gene, effects which cannot be related solely to their ability to reduce germinal cell apoptosis. Use of this culture system should help to test the effect of any hormone or factor on those steps in order to understand better their regulation.

Induction of specific base-pair substitutions in E. coli trpA mutants by chloroethylene oxide, a carcinogenic vinyl chloride metabolite.

Chloroethylene oxide (CEO), an ultimate carcinogenic metabolite of vinyl chloride, induces base-pair substitution mutations but not frameshift mutations in bacteria. The mutational specificity of CEO was investigated in Escherichia coli, using the trpA mutants developed by Yanofsky. Reversion frequencies to tryptophan prototrophy were analysed, and CEO was found to induce more GC----AT transitions than AT----TA transversions, in addition to a low frequency of other types of substitution. This specificity indicates that CEO is mutagenic through a miscoding DNA adduct. The results are discussed in relation to the various CEO-DNA adducts formed and to their reported or expected mispairing properties.

Mutagenicity and toxicity of chloroethylene oxide and chloroacetaldehyde.

Exposure of several trp-auxotrophic Escherichia coli strains, carrying base-pair substitutions, to chloroethylene oxide or chloroacetaldehyde (two metabolites of vinyl chloride) increased the mutation frequency to tryptophan prototrophy. Strong cytotoxic and mutagenic effects were observed with 2.5 mM chloroethylene oxide, while a higher concentration of chloroacetaldehyde (100 mM) exhibited a mutagenic effect which was 400 times lower.

FSH stimulation of cytosolic protein synthesis in cultured pig Sertoli cells.

The effects of FSH on the cytosolic protein synthesis by a primary culture of immature porcine Sertoli cells were studied. Cells were cultured in a chemically-defined medium for 3 days and, on day 3, they were incubated for 40 h in another medium containing labelled amino-acids either in the presence or absence of 50 ng/ml porcine FSH (pFSH). In control cells, about 107 spots (pI in the range of 5 to 8) were identified by a two-dimensional polyacrylamide gel electrophoresis of the radiolabelled cytosolic proteins. pFSH treatment produced a marked increase of seven proteins whose molecular weights and isoelectric points are respectively comprised between 25 to 58 K and 5.5 to 5.8. In addition, pFSH treatment induced a slight but constant increase of two other proteins (mol. wt: 24 and 12 K and isoelectric point: 5.3).