Genetic Strains Research Center, National Institute of Genetics, Mishima, Japan.
Dev Dyn. 2011 Jul;240(7):1779-92. doi: 10.1002/dvdy.22661. Epub 2011 May 18.
We describe here the isolation and cytogenetic characterization of three meiotic prophase I mutants, denoted ietsugu (its), iesada (isa), and iemochi (imo), isolated by a novel N-ethyl-N-nitrosourea mutagenesis screen for adult zebrafish gonadogenesis. Histological examination and flow cytometry analysis of testes from these mutants showed that each contained neither spermatids nor sperm. Staining for Sycp3 and cleaved Caspase-3 and TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end-labeling) assay further revealed that its had defects at the onset of meiosis, and that isa and imo spermatocytes failed to progress past the zygotene stage with apoptosis occurring in the testicular somatic cells. Staining for phosphorylated histone H2AX showed that foci formation in leptotene spermatocytes was disrupted in isa and imo. Furthermore, in vitro differentiation experiments revealed the possibility that the defects and sterility associated with mutations were germ line autonomous. Our results thus indicate that each responsible gene is necessary for meiotic progression during spermatogenesis and for male fertility.
我们在此描述了三个减数分裂前期 I 期突变体的分离和细胞遗传学特征，这些突变体分别命名为 ietsugu（its）、iesada（isa）和 iemochi（imo），是通过一种新的 N-乙基-N-亚硝基脲诱变筛选成年斑马鱼性腺发生而分离得到的。对这些突变体的睾丸进行组织学检查和流式细胞术分析表明，每个突变体既没有精母细胞也没有精子。Sycp3 和裂解 Caspase-3 的染色以及 TUNEL（末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸缺口末端标记）检测进一步表明，its 在减数分裂开始时存在缺陷，isa 和 imo 精母细胞未能通过合线期，睾丸体细胞发生凋亡。磷酸化组蛋白 H2AX 的染色表明，isa 和 imo 的细线期精母细胞中的焦点形成受到破坏。此外，体外分化实验表明，与突变相关的缺陷和不育可能是生殖系自主的。因此，我们的结果表明，每个负责的基因对于精子发生过程中的减数分裂进展和雄性生育能力都是必要的。
