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1.
The Mus musculus domesticus Tdy allele acts later than the Mus musculus musculus Tdy allele: a basis for XY sex-reversal in C57BL/6-YPOS mice. 总被引:3,自引:0,他引:3
Consomic C57BL/6 males, carrying either the Mus musculus musculus-derived C57BL/6 Y chromosome or the Mus musculus domesticus-derived Poschiavinus Y chromosome, were outcrossed to females of the inbred strains C3H/Bi and CXBH/By and to females of the random bred strain MF1/Ola. In a study at 12.5 days post coitum, gonads of XYC57 and XYPOS fetuses were assessed for the presence of testicular cords. It was found that XYPOS fetuses had a later onset of testicular development than XYC57 fetuses. Limb development, which was monitored as a measure of overall development, was unaffected by the strain of Y present. These data were supported by a longitudinal study in which the increased growth rate of the testes relative to undifferentiated gonads, was also shown to be delayed in XYPOS fetuses. The extent of the delay was estimated to be approximately 14 h. It is concluded that this delay in the onset of testicular differentiation must be caused by differences between the two Y-chromosome types, most probably allelic differences in the testis determinant Tdy. 相似文献
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Developmental Changes in Polypeptide Composition of, and Precursor Incorporation into, Cellular and Subcellular Fractions of Rat Cerebral Cortex 总被引:4,自引:4,他引:0
Abstract: Neuronal-enriched and glial-enriched fractions from rat cerebral cortex at 2. 5, 9, 14 and 23 days postnatally, and subcellular fractions from 2, 14 and 46 day old rat were prepared. The polypeptide composition of all fractions was analysed by sodium dodecyl sulphate (SDS) polyacrylamide gel electro-phoresis and quantified by densitometry. Fifty-nine polypeptides (mol. wts., 13,200–251,000) were resolved in the cell fractions of which the majority remained unchanged throughout postnatal development. Three polypeptides (mol. wts., 102,000, 56,000, 53,700) were found to increase in amount devel-opmentally in both cellular fractions, the latter two showing a peak in relative amount on day 14 and a subsequent decline. Three polypeptides (mol. wts., 47,000, 28,200, 17,400) were found to be common to the glial-enriched fraction as well as the myelin fraction, and all showed a developmental increase. The neuronal-enriched fraction was found to be enriched in five polypeptides of which one (mol. wt., 51,900) showed a developmental increase after ten days postnatally, the others (mol. wts., 178,700, 142,000, 109,000, 24,000) showing a decrease. In vitro incorporation of [35 S]-methionine into the glial-enriched fraction was carried out, and a developmental decline was observed in the labelling of a polypeptide of 42,000 mol. wt. 相似文献
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Calcium-dependent priming of DNA synthesis in isolated rat liver nuclei 总被引:24,自引:0,他引:24
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The caffeine-sensitive Ca2+ store in bovine adrenal chromaffin cells; an examination of its role in triggering secretion and Ca2+ homeostasis 总被引:1,自引:0,他引:1
The effect of caffeine on catecholamine secretion and intracellular free Ca2+ concentration [( Ca2+]i) in bovine adrenal chromaffin cells was examined using single fura-2-loaded cells and cell populations. In cell populations caffeine elicited a large (approximately 200 nM) transient rise in [Ca2+]i that was independent of external Ca2+. This rise in [Ca2+]i triggered little secretion. Single cell measurements of [Ca2+]i showed that most cells responded with a large (greater than 200 nM) rise in [Ca2+]i, whereas a minority failed to respond. The latter, whose caffeine-sensitive store was empty, buffered a Ca2+ load induced by a depolarizing stimulus more effectively than those whose store was full. The caffeine-sensitive store in bovine chromaffin cells may be involved in Ca2+ homeostasis rather than in triggering exocytosis. 相似文献
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Low molecular mass GTP-binding proteins of adrenal chromaffin cells are present on the secretory granule 总被引:8,自引:0,他引:8
Adrenal medullary homogenates and chromaffin granule membranes were separated by SDS-polyacrylamide gel electrophoresis and GTP-binding proteins detected using [alpha-32P]GTP binding to nitrocellulose blots. Four GTP-binding polypeptides of 24, 22, 20 and 18 kDa were routinely found in medullary homogenates and all were also found in isolated chromaffin granule membranes. The GTP-binding polypeptides co-sedimented with granule membrane markers following separation on sucrose gradients. On the basis of trypsin sensitivity and resistance to extraction, the GTP-binding proteins appeared to be tightly bound to the cytoplasmic surface of the granules. One or more of the secretory granule GTP-binding proteins could be involved in exocytosis in adrenal chromaffin cells. 相似文献
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