Expression profiling of rainbow trout testicular development and spermatogenesis

Trout spermatogenesis proceeds seasonally in a way that all morphological and cellular events tend to be synchronized. We thus used gonads at key stages of the male reproductive cycle together with isolated germ cell populations to study the changes in gene expression underlying testis development. Statistical analysis followed by clustering of expression profiles allowed the discrimination of sequential events of gene activation or repression during testis development and/or throughout the germline. 38 samples covering 6 developmental stages (as defined in Gomez et al. 1998 Biol. Reprod. 58, 483-491) and 3 isolated germ cell populations were analysed. This included: - Testes at early stages containing slowly-dividing type A spermatogonia (Stage_I, n=5) or growing numbers of actively-dividing type B spermatogonia (Stages_IIa, n= 4; Stage_IIb, n= 4) - Maturing testes containing in addition large numbers of meiotic spermatocytes (Stage_IIIb, n=3) and post-meiotic spermatids (Stage_V, n=4) - Spawning testes containing essentially mature spermatozoa (Stage_VIII, n=3) - Fractions of isolated germ cells enriched in spermatogonia (Spermatogonia, N=6), spermatocytes (Spermatocyte, N=6) and spermatids (Spermatid, N=3).