Identification of androgen-responsive genes in fish testis

Sexual steroids play an important role in gonad maturation in all vertebrates. However, the molecular mechanisms regulating of spermatogenesis in seasonal breeding species are yet poorly understood. In this study we investigated the effects of testosterone and 11-ketotestosterone (11KT) - a teleost fish specific androgen - on testicular gene expression at the onset of puberty in the rainbow trout, Oncorhynchus mykiss. Rainbow trout 13 months old were used. Immature males (spermatogonia only, stage I-II) were submitted to androgen supplementation by hormone implants for 7 or 14 days. This included : - untreated animal controls (N=14) - animals subjected to testosterone supplementation (0.1mg) for 7 days (N=5) - animals subjected to testosterone supplementation (0.2mg) for 7 days (N=4) - animals subjected to testosterone supplementation (0.2mg) for 14 days (N=5) - animals subjected to 11-ketotestosterone supplementation (0.25mg) for 7 days (N=7). Individual testes were recovered for microarray experiments and histological analyses. Circulating levels of corresponding androgens were also determined.