Molecular Biological Studies of the Mechanisms in Amphibian Spermatogenesis.

1 .利用卵泡刺激素在水螈睾丸碎片器官培养中从次级精原细胞向初级精母细胞分化。当在单独促卵泡激素（FSH）存在下培养富含次级精原细胞的睾丸碎片时，到第二周时，超过一半的囊肿出现了初级精原细胞。这些结果表明卵泡刺激素是精原细胞向原代精母细胞分化的必要条件和充分条件。成熟精子的鞭毛长度是如何确定的？独眼蟾和爪蟾圆形精子中鞭毛生长的比较：独眼蟾精子的鞭毛长度是爪蟾精子的13倍。独眼蟾精细胞鞭毛生长的速度和周期是爪蟾的2 ~ 3倍。鞭毛伸长的时间几乎与微管蛋白合成的时间一致。独眼蟾和爪蟾在微管蛋白合成速率和周期上的差异似乎是由于两种动物微管蛋白mrna的稳定性不同。非洲爪蟾精子细胞中精子特异性基本核蛋白（SPs）的合成及SP4 mRNA在原代精子细胞中的表达：在圆形精子的同步培养中，SP1, 3-5的合成在第3天开始。从圆形精子的CDNA文库中分离到SP4和sp5的CDNA克隆。Northern blot结果显示，SP4和5 mrna存在于原代精母细胞和圆形精母细胞中。这表明SP4和sp5基因在初级精母细胞阶段被转录，而在圆形精母细胞阶段被翻译。manchette（微管束）在Cynops pyrrhogaster精细胞核伸长中的作用：微管在精细胞核形成中的作用尚未确定。我们发现蝾螈长形精子的manchette结构对Ca^<2+>和低温处理具有抗性。从睾丸低温稳定微管中提取的1M NaCl Sup在37℃时促进微管蛋白的聚合，在0℃时抑制微管蛋白的解聚，并呈剂量依赖性。这些结果表明，1M NaCl Sup含有微管相关蛋白MAPs（微管相关蛋白），可以促进微管蛋白的聚合，并赋予抗微管蛋白解聚的能力。少

I. Differentiation from secondary spermatogonia to primary spermatocytes by FSH in organ culture of testes fragments from the newt. Cynops pyrrhogaster : When testes fragments rich in secondary spermatogonia were cultured in the presence of follicle-stimulating hormone (FSH) alone, primary spermatocytes appeared in more than half of the cysts by the second week. These results indicate that FSH is indispensable and sufficient for the differentiation from spermatogonia to primary spermatocytes.II. How is the flagellar length of mature sperm determined ? Comparison of flagellar growth in round spermatids between Cynops and Xenopus : The flagellar length of Cynops sperm is 13 times longer than that of Xenopus sperm. The rate and period of flagellar growth in Cynops spermatids were 2 to 3-fold those in Xenopus. The period of flagellar elongation almost coincided with that of tubulin synthesis. The differences in the rate and period of tubulin synthesis between Cynops and Xenopus seems to be … More due to the difference in the stability of tubulin mRNAs between the two species.III. Synthesis of sperm-specific basic nuclear proteins (SPs) in spermatids and expression of SP4 mRNA in primary spermatocytes from Xenopus laevis : In synchronous culture of round spermatids, the synthesis of SP1, 3-5 began by day 3. CDNA clones for SP4 and 5 were isolated from a cDNA library from round spermatids. The Northern blots showed that SP4 and 5 mRNAs were present in primary spermatocytes as well as in round spermatids. This result shows that SP4 and 5 genes are transcribed in the primary spermatocyte stage but are translated at the round spermatid stage.IV. Role of manchette (microtubule bundles) in nuclear elongation in spermatids from Cynops pyrrhogaster : The role of microtubules in nuclear shaping of spermatids has yet to be determined. We found that manchette structure in newt elongate spermatids is resistant to the treatment of Ca^<2+> and low temperature. 1M NaCl Sup extracted from low temp-stable microtubules in testes promoted polymerization of tubulin at 37 C and resisted depolymerization at 0 C in a dose-dependent manner. These results indicate that 1M NaCl Sup contains MAPs (microtubule associated proteins) which promote tubulin polymerization and confer the resistance against tubulin depolymerization. Less