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Proc Natl Acad Sci U S A. 1998 Aug 18;95(17):10015-9.

Mutation frequency declines during spermatogenesis in young mice but increases in old mice.

Author information

  • 1Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78284-7762, USA. walter@uthscsa.edu

Abstract

Five percent of live-born human offspring will have a genetic disorder. Of these, 20% are because of germ-line de novo mutations. Several genetic diseases, such as neurofibromatosis and Duchenne muscular dystrophy, are associated with a high percentage of de novo germ-line mutations. Until recently, a direct analysis of spontaneous mutation frequencies in mammalian germ cells has been prevented by technical limitations. We have measured spontaneous mutation frequencies in a lacI transgene by using enriched populations of specific spermatogenic cell types. Similar to previously published results, we observed a lower mutation frequency for seminiferous tubule cell preparations, which contain all stages of spermatogenesis, relative to somatic tissues. We made the unexpected observation of a decline in mutation frequency during spermatogenesis, such that the mutation frequencies of type B spermatogonia and all subsequent stages of spermatogenesis are lower than the frequency for primitive type A spermatogonia. In addition, spermatogenic cells from old mice have significantly increased mutation frequencies compared with spermatogenic cells from young or middle-aged mice. Finally, the mutation frequency was observed to increase during spermiogenesis in postreplicative cell types when spermatogenic cells were obtained from old mice.

PMID:
9707592
[PubMed - indexed for MEDLINE]
PMCID:
PMC21453
Free PMC Article
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