Molecular identification of an androgen receptor and its changes in mRNA levels during 17α-methyltestosterone-induced sex reversal in the orange-spotted grouper Epinephelus coioides

Androgens play a crucial role in sex differentiation, sexual maturation, and spermatogenesis in vertebrates. The action of androgens is mediated via androgen receptors (ARs). The present study reports the cloning of the cDNA sequence of the or in the orange-spotted grouper, with high expression in testis and relatively low in subdivision of brain areas. The cDNA sequence of or was 2358 bp, encoding a protein of 759 amino acids (aa). Phylogenetic analysis showed that the at cDNA sequence was closely related to that of threespot wrasse (Halichoeres trimaculatus) and medaka (Oryzias latipes) ar beta. As deduced from the phylogenetic tree and the high amino acid identity with the AR beta, subtype of other teleosts, grouper or seems to be more closely related to the beta than the alpha subtype cloned to date. In the first week after 17 alpha-methyltestosterone (MT) implantation, the transcript levels of or in the hypothalamus declined significantly, and consistently stayed at low level expression to the second week, but increased back to the control levels in the third and fourth week. In the gonad, the mRNA expression of or was not changed in the first week compared with the control, but increased significantly in the second week, consistently reached the highest level in the third week, dropped slightly but still higher than that of the control in the fourth week. The expression pattern of or in hypothalamus and gonad during MT-induced sex reversal suggests the involvement of or in regulating this process in the orange-spotted grouper. The present study provides the data of the changes in the mRNA levels of or during MT-induced sex reversal in detail to help understand the complicated signals under sex reversal. (C) 2012 Elsevier Inc. All rights reserved.