CHANGES IN PROTOONCOGENE ACTIVITY IN THE TESTIS OF THE FROG, RANA-ESCULENTA, DURING THE ANNUAL REPRODUCTIVE-CYCLE

Proto-oncogenes are said to influence the regulation of cellular growt h and differentiation. Myc, Fos, Jun, and Mos protein localization has been studied by immunocytochemistry in the testis of the frog, Rana e sculenta, during the annual reproductive cycle. Oncoproteins have bean localized in the primary and secondary (I and II) spermatogonia (SPG) . Myc and Mos also appear in I and II spermatocytes (SPC) while Jun ap pears in II SPC. Myc, Fos, and Jun in SPG translocate in the nucleus d uring the periods of active spermatogenesis. Myc, Fos, and Jun are als o localized in Sertoli cells. Fos is present in interstitial cells dur ing the period characterized by the androgen peak which precedes the s harp increase of estradiol. It is suggested that proto-oncogene activi ty exerts a regulatory role in steroidogenesis and spermatogenesis. (C ) 1995 Academic Press, Inc.