Stage-specific gene expression during spermatogenesis in the dogfish (Scyliorhinus canicula).

International audienceIn the dogfish testis the cystic arrangement and polarisation of germ cell stages makes it possible to observe all stages of spermatogenesis in a single transverse section. By taking advantage of the zonation of this organ we have used suppressive subtractive libraries construction, real-time PCR and in situ hybridisation to identify 32 dogfish genes showing differential expressions during spermatogenesis. These include homologues of genes already known to be expressed in the vertebrate testis, but found here to be specifically expressed either in pre-meiotic and/or meiotic zones (ribosomal protein S8, high-mobility group box 3, ubiquitin carboxyl-terminal esterase L3, 20beta-hydroxysteroid dehydrogenase or cyclophilin B), or in post-meiotic zone (speriolin, Soggy, zinc finger protein 474, calreticulin or phospholipase c-zeta). We also report for the first time testis-specific expression patterns for dogfish genes coding for A-kinase anchor protein 5, ring finger protein 152 or F-box only protein 7. Finally, the study highlights the differential expression of new sequences whose identity remains to be assessed. This study provides the first molecular characterisation of spermatogenesis in a chondrichthyan, a key species to gain insight into the evolution of this process in gnathostomes