Molecular cloning, characterization and expression profiles of three estrogen receptors in protogynous hermaphroditic orange-spotted grouper (Epinephelus coioides)

National 863 Program of China [2006AA10A414, 2010AA10A402]; National Science Foundation of China [U0631007, 30871914]; National Key Technology RD Program [2006BAD09A14, 2007BAD29B01]; Special Fund for Agro-Scientific Research in Public Interest [200903046Estrogen plays key roles in vertebrate reproductive system via estrogen receptors (ERs) as mediating pathways. In the present study, three full-length ERs cDNA sequences were isolated from a protogynous teleost, the orange-spotted grouper (Epinephelus coioides), and were 2235 bp for gER alpha, 1967 bp for gER beta 1 and 2158 bp for gER beta 2, respectively. Phylogenetic and amino acid alignment analyses showed that each gER was clustered in the corresponding taxonomic groups of the perciformes and exhibited high evolutional conservation in functional domains. RT-PCR revealed that gERs expressed at different levels in all the obtained tissues. gER alpha highly expressed in mature ovaries, gER beta 1 mainly expressed in immature ovaries and gER beta 2 varied greatly during ovarian development. During female to male sex reversal induced by 17 alpha-methyltestosterone (MT) implantation, gER alpha decreased gradually, gER beta 1 increased gradually, and gER beta 2 decreased firstly and recovered subsequently in male stage. The present study speculated the potential roles of gERs during female maturation and female to male sex reversal induced by MT in the protogynous grouper E. coioides. (C) 2011 Elsevier Inc. All rights reserved