Hormonal influence on amylase gene expression during Seabass (Lates calcarifer) larval development

Abstract

α-Amylase gene expression was detected in newly hatched seabass (Lates calcarifer) larvae and peaked at around first feeding. This suggests a greater importance of carbohydrates during early larval development than might be expected for carnivorous fishes. In vivo cortisol and triiodothyronine (T3) treatment of seabass larvae upregulated α-amylase gene expression. The identification of a functional glucocorticoid-response element (GRE) on the amylase gene promoter indicates that cortisol (glucocorticoid) stimulation of amylase gene expression is direct via GRE. However no TRE (thyroid-response element) was found on the amylase gene and its promoter, and various concentrations of T3 (1nM-10μM) also did not induce α-amylase gene promoter activity in rat AR42-J cells transfected with the promoter construct, unlike dexamethasone treatment. This suggests that T 3 stimulation of amylase gene expression in vivo was indirect, probably secondary to its promotion of one or more developmental processes. © 2004 Elsevier Inc. All rights reserved.