XRCC-1 EXPRESSION DURING MALE MEIOSIS IN THE MOUSE

XRCC1 is involved in DNA strand-break repair, homologous recombination , and sister chromatid exchange and is expressed as a low-abundance mR NA with elevated expression in testis. The purpose of this study was t o determine whether specific spermatogenic cell types have elevated Xr cc-1 expression and whether expression levels change in the testis wit h increased age. Northern blot analysis of mRNA prepared from testes o f 15-, 25-, and 60-day-old mice revealed a single hybridizing band of 2.2 kb. Quantitative RNase protection assays revealed no changes in th e level of Xrcc-1 expression in testis relative to DNA content among 6 -, 12-, 18-, 24-, or 28-mo-old mice. Finally, reverse transcription co upled polymerase chain reaction amplification results demonstrated tha t Xrcc-1 expression is most abundant in pachytene spermatocytes and ro und spermatids with low expression in Sertoli cells, types A and B spe rmatogonia, preleptotene spermatocytes, and leptotene plus zygotene sp ermatocytes. The relatively abundant Xrcc-1 expression in pachytene sp ermatocytes and round spermatids suggests that Xrcc-1 is involved in D NA strand-break repair associated with meiotic recombination in additi on to its previously implicated role in strand-break repair associated with base excision repair.