The social status of the male Nile tilapia (Oreochromis niloticus) influences testis structure and gene expression.

Dominant and territorial behaviour are known social phenomena in cichlids and social stress influences reproduction and growth. The gonadotropic hormones trigger spermatogenesis and subordinate males have typically lower levels of gonadotropins than dominant males. In this study, we compared testis morphology and gene expression of dominant and subordinate Nile tilapia males (d- and s-males) in socially stable communities.

Tert expression and telomerase activity in gonads and somatic cells of the Japanese medaka (Oryzias latipes).

A telomerase reverse transcriptase (Tert) encoding gene was cloned from the testis of the teleost fish Oryzias latipes. The expression pattern of Japanese medaka tert (Ola_tert) was analyzed by reverse transcription-polymerase chain reaction and in situ hybridization. Ola_tert was expressed in embryonic stages as well as in differentiated adult tissues.