Molecular identification of genes involved in testicular steroid synthesis and characterization of the response to gonadotropic stimulation in the Senegalese sole (Solea senegalensis). Solea senegalensis

In male teleosts, testicular steroids are essential hormones for the regulation of spermatogenesis and their production is regulated by pituitary gonadotropins. In the Senegalese sole (Solea senegalensis), an economically important flatfish with semi-cystic and asynchronous spermatogenesis, the endocrine mechanisms involved in the regulation of spermatogenesis, particularly regarding the production and regulation of testicular steroids, are not well understood.This study aimed at describing the transcriptomic changes taking place in the Senegalese sole testis in response to hCG stimulation in vivo. Gene expression analysis by microarray identified 90 differentially expressed genes in the testis in response to hCG administration, including genes potentially involved in steroidogenesis, progression of spermatogenesis and germ cell maturation and cytoskeletal organization. Our results provide evidence for the first time that key genes involved in the regulation of steroid production and spermatogenesis in the Senegalese sole testis are under gonadotropic control. Overall design: Testes samples from saline- and hCG-injected male Senegalese sole (8 fish per group) were pooled separatedly. Pooled testicular RNAs from each group were amplified and the resulting cRNAs labelled with Cy3 and Cy5, respectively, mixed in equal amounts and hybridized to the microarray for 17 h at 60 ºC. Each hybridization was performed in duplicate.