Conversion from mitosis to meiosis: Morphology and expression of proliferating cell nuclear antigen (PCNA) and Dmc1 during newt spermatogenesis
Conversion from mitosis to meiosis: Morphology and expression of proliferating cell nuclear antigen (PCNA) and Dmc1 during newt spermatogenesis
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DOI：
10.1046/j.1440-169x.2000.00544.x
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发表时间：
2000-12
期刊：
影响因子：
4.6
通讯作者：
T. Yazawa;Takashi Yamamoto;Y. Nakayama;Shuji Hamada;S. Abe
中科院分区：
文献类型：
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作者：
T. Yazawa;Takashi Yamamoto;Y. Nakayama;Shuji Hamada;S. Abe
从有丝分裂到减数分裂的转换是配子细胞祖细胞特有的现象;然而，人们对这种转换的机制知之甚少。为此，本文报道了蝾螈精子发生减数分裂起始过程中的一些形态学和分子生物学变化。原位形态学研究表明，精原细胞阶段包括两个阶段：有丝分裂早期（G1-G4）和有丝分裂晚期（G5-G8）。从次级精原细胞到初级精母细胞的形态转换发生在减数分裂前DNA复制的中间阶段。增殖细胞核抗原（PCNA）是一种DNA聚合酶-δ辅助蛋白，在精原细胞中的表达在G1期较弱，在DNA合成（S）期最高，在G2期降低，在分裂细胞中检测不到。DMC 1（破坏的减数分裂cDNA）的蝾螈同源物的互补DNA被分离出来，DMC 1是一种在减数分裂期间特异性活性的大肠杆菌RecA样蛋白。蝾螈Dmc 1 mRNA的表达显着的preleptotene阶段，这持续到精子细胞阶段。这些结果为研究蝾螈精原细胞从有丝分裂向减数分裂转化的机制提供了基础。
The conversion from mitosis to meiosis is a phenomenon specific to the cellular progenitors of gametes; however, the mechanism or mechanisms responsible for this conversion are poorly understood. To this end, some morphological and molecular changes that occur during the initiation of meiosis in newt spermatogenesis are reported in the present paper. In situ morphologic studies revealed that spermatogonial stages comprise two phases: early mitotic generations (G1–G4) and late mitotic generations (G5–G8). Morphologic conversion from secondary spermatogonia to primary spermatocytes occurred during the intermediate stage of premeiotic DNA replication. The expression of proliferating cell nuclear antigen (PCNA), a DNA polymerase‐delta auxiliary protein, in spermatogonia was weak in G1, highest during DNA synthesis (S), decreased in G2 and was not detectable in dividing cells. Complementary DNA for newt homologs of DMC1 (disrupted meiotic cDNA), which is an Escherichia coli RecA‐like protein specifically active during meiosis, were isolated. The newt Dmc1 mRNA was first expressed significantly during the preleptotene stage and this continued into the spermatid stage. These observations present a basis for investigating the mechanism(s) controlling the conversion of newt spermatogonial cells from mitosis to meiosis.