Changes in mutagenesis sensitivity with maturation of male germ cells as revealed by the Medaka specific-locus test system

青鳉特异性基因座测试系统揭示了诱变敏感性随雄性生殖细胞成熟的变化

基本信息

批准号：
04454605
负责人：
SHIMA Akihiro
金额：
$ 2.88万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

The purpose of the present study is to elucidate in detail the changes in mutagenesis sensitivity of male germ cells during spermatogenesis and spermiogenesis as well. For this purpose, the Medaka specific-locus test system developed by Shima and Shimada was used. The genetic endpoints employed were dominant lethal mutations, total specific-locus mutations and viable specific-locus mutations. The wild type male Medaka were mutagenized with gamma-rays. They were allowed to mate with non-treated tester females which were homozygous recessive at the three marker loci. Regarding the induction of dominant lethals with gamma-rays, the rates were highest during 1-3 days after exposure corresponding to the exposure of male germ cells at the stage of spermatozoa, followed by monotonous decrease toward 30th day after male exposure, indicating a high correlation between mutability and maturation. This trend was also the case for the total specific-locus mutations as well as viable specific-locus mutations. It was concluded, therefore, that the changes in mutability induced with gamma-rays in terms of dominant lethals and specific-locus mutations in the male germ cells run almost in parallel with the maturation (differentiation) of the male germ cells ranging from stem spermatogonia to mature spermatozoa. To understand the molecular mechanisms underlying these genetic endpoints, the genomic DNA of individual dominant lethal embryos were extracted and the DNA fingerprints were prepared by using AP-PCR.It was found that the rate of DNA alterations in terms of band loss from the fingerprint is more freuent compared to that in the normal sibling.

本研究的目的是详细阐明在精子发生和精子发生过程中雄性生殖细胞诱变敏感性的变化。为此，使用了由Shima和Shimada开发的Medaka特异性基础测试系统。所采用的遗传终点是主要的致命突变，总特异性基因素突变和可行的特异性基础突变。野生型男性Medaka用伽马射线诱变。他们被允许与未经处理的测试仪女性交配，这些雌性在三个标记基因座处是纯合隐性的。关于用γ射线诱导主要的致死性，在暴露后1-3天内，与男性生殖细胞在精子阶段暴露相对应的速率最高，然后单调降低到男性暴露后的第30天，这表明Mutability和成熟之间的相关性很高。总特异性局限器突变以及可行的特异性基因级突变也是这种趋势。因此，得出的结论是，在雄性生殖细胞中的主要致命致死性和特异性基础素突变方面，γ射线诱导的可突变性的变化几乎与雄性生殖细胞的成熟（分化）平行于茎精子症到成熟的精子的成熟（分化）。为了了解这些遗传终点的分子机制，提取了单个显性致命胚胎的基因组DNA，并通过使用AP-PCR制备了DNA指纹。与正常sibly相比，与指纹损失的DNA改变速率相比，DNA改变的速率更加自由。