Abstract: 340

TELOMERE LENGTH INCREASES DURING MALE GERM CELL DIFFERENTIATION.

Maria V. Achi¹ , Neelakanta Ravindranath^{1 *}, Martin Dym^{1 *}
Department of Cell Biology, Georgetown University Medical Center, Washington, DC 20007 ¹

Spermatogenesis is a complex process beginning with the proliferation of type A spermatogonia and terminating with morphologically distinct spermatozoa. Telomeres that cap the ends of chromosomes progressively shorten with each cellular division in normal somatic cells leading to replicative senescence. Since very little is known about changes in the telomere length during male germ cell differentiation, we performed a comparative analysis of telomere length in immature rat testis (9-day old) containing type A spermatogonia, with adult rat testis consisting of more differentiated germ cells. Mean telomere length in the immature testis was shorter in comparison to the mean telomere length in the adult testis, suggesting that type A spermatogonia probably have shorter telomeres than more differentiated germ cells. We next isolated type A spermatogonia from 9-day old rat testis, and pachytene spermatocytes and round spermatids from adult rat testis. Pachytene spermatocytes consistently exhibited longer telomeres in comparison with type A spermatogonia. Epididymal spermatozoa exhibited the longest mean telomere length. In germ cells, the telomere length is maintained by the activity of the telomerase enzyme that synthesizes telomeric repeats de novo. Telomerase activity was very high in type A spermatogonia, decreased in pachytene spermatocytes and round spermatids, and was totally absent in epididymal spermatozoa. In summary, these results indicate that telomere length is inversely correlated with the telomerase activity expression during male germ cell differentiation (Supported by NIH Grants HD00627 and HD33728).

    This abstract is being presented on Monday, August 2 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.