Mixed spermatogenic germ cell nuclear extracts exhibit high base excision repair activity.
Spermatogenic cells exhibit a lower spontaneous mutation frequency than somatic tissues in a lacI transgene and many base excision repair (BER) genes display the highest observed level of expression in the testis. In this study, uracil-DNA glycosylase-initiated BER activity was measured in nuclear extracts prepared from tissues obtained from each of three mouse strains. Extracts from mixed spermatogenic germ cells displayed the greatest activity followed by liver then brain for all three strains, and the activity for a given tissue was consistent among the three strains. Levels of various BER proteins were examined by western blot analyses and found to be consistent with activity levels. Nuclear extracts prepared from purified Sertoli cells, a somatic component of the seminiferous epithelium, exhibited significantly lower activity than mixed spermatogenic cell-type nuclear extracts, thereby suggesting that the high BER activity observed in mixed germ cell nuclear extracts was not a characteristic of all testicular cell types. Nuclear extracts from thymocytes and small intestines were assayed to assess activity in a mitotically active cell type and tissue. Overall, the order of tissues/cells exhibiting the greatest to lowest activity was mixed germ cells > Sertoli cells > thymocytes > small intestine > liver > brain.
Department of Cellular and Structural Biology and Department of Pathology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78284, USA. walter@uthscsa.edu
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Intano
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McMahan
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Walter
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McCarrey
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Walter
D000818:Animals; D015153:Blotting, Western; D001923:Brain Chemistry; D002457:Cell Extracts / Q000737:chemistry / Q000494:pharmacology; D002467:Cell Nucleus / Q000737:chemistry*; D004247:DNA / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011088:DNA Ligases / Q000378:metabolism; D019951:DNA Polymerase beta / Q000378:metabolism; D004260:DNA Repair; D008099:Liver / Q000737:chemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D009711:Nucleotides / Q000378:metabolism; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D013094:Spermatozoa / Q000737:chemistry* / Q000166:cytology
D002457:Cell Extracts; D009711:Nucleotides; D009841:Oligonucleotides; D011506:Proteins; D004247:DNA; D019951:DNA Polymerase beta; D011088:DNA Ligases