1993 Fiscal Year Final Research Report Summary
Changes in mutagenesis sensitivity with maturation of male germ cells as revealed by the Medaka specific-locus test system
| Project/Area Number |
04454605
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
放射線5生物学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SHIMA Akihiro The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (60011590)
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| Project Period (FY) |
1992 – 1993
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| Keywords | the Medaka (Oryzias latipes) / specific-locus test system / male germ cells / maturation / dominant lethals / total mutation / viable mutation / DNA alterations |
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| Research Abstract |
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.
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