Induction of vitellogenin in cultured fish: Vitellogenin gene expression response of blue fin and yellow fin breams to injected 17 -estradiol

Aquatic organisms in the coastal regions are often exposed to many anthropogenic effluents. Kuwait Bay receives considerable quantities of sewage and industrial effluents, and thus, naturally, many endocrine disrupting chemicals (EDCs) find their way into the coastal waters. These EDCs could influence the physiology of the aquatic organisms inhabiting the coastal region. Response of two important local fish of aquaculture importance, bluefin bream (Sparidentax hasta) and yellowfin bream (Acanthopagrus latus) was evaluated by injecting a standard vitellogenin inducer, 17 β-estradiol (17 BEST). The inducer was used at 2, 4 and 6 µg/fish (injected intraperitoneally) to induce vitellogenin production in juvenile fish (150-200 g). There was a dose-dependent Vtg induction response as evidenced by a qualitative immune-dot assay. All levels significantly enhanced Vtg gene expression, as early as one-hour post injection. The expression was noticed to be the highest in liver tissue at 6 h post injection. The bluefin bream was used for amplification of the Vtg gene yielding 282 bp product which was sequenced. This indicated a 97% sequence similarity with the Vtg gene sequence of European seabream, S. aurata. Key words: Induction, Vtg, EDCs, Kuwait, fish, effluent.