Cloning and sequencing of Tert gene in gilthead seabream, Sparus aurata, and European seabass, Dicentrarchus labrax: Expression patterns in germ and somatic cells

Tert gene encodes a catalytic subunit of the enzyme telomerase, which protects telomeres from abnormal folds and their degradation. In mammals, the activity of telomerase in tissues of adults is limited to stem cells with high potential for proliferation, finding expression in the cells of the germline, tumors and neoplastic cells, although the Tert gene seems to be ubiquitous in fish. To gain insight on Tert implication for fish gonad cell differentiation and gametogenesis progress, we cloned the Tert cDNA of two reared marine fish species, gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax), and their quantitative and qualitative Tert mRNA expression were analyzed. Two Tert transcripts encoding proteins which differ at their functional C-terminal end were isolated from gilthead seabream, whereas only one Tert transcript was identified from European seabass. The qPCR assays showed that Tert genes are expressed ubiquitously in both fish species, and the highest expression levels were found in gonads and particularly in differentiating or maturating germ cells, which could suggest an important role of Tert genes in gametogenesis and cell-tissue development of fish species.