Transcriptional variants of Dmrt1 and expression of four Dmrt genes in the blunt snout bream, Megalobrama amblycephala

Abstract

Doublesex and Mab3 related transcription factor (DMRT), characterized by a conserved DM domain, function as sex-related transcription factors and also play critical roles in ontogenesis. In this study, 4 Dmrt genes in the blunt snout bream, Megalobrama amblycephala, were identified, characterized and their mRNA expression in different adult organs, during embryogenesis and gonadal development in larvae were determined by quantitative real time PCR. There are 4 Dmrt1 isoforms in the M. amblycephala genome, which were expressed highly in the testis and weakly in the ovary. The complete cDNAs of the M. amblycephala Dmrt2a, Dmrt2b and Dmrt3 were predicted to encode 510, 328 and 449 amino acids, respectively. The M. amblycephala Dmrt2a mRNA peaked at 11hpf (hour post fertilizing) during early embryonic stages, while Dmrt2b was highly expressed during late embryonic stages. Both the M. amblycephala Dmrt2a and Dmrt2b were expressed highly in the gill and exhibited a sexually dimorphic expression pattern. The M. amblycephala Dmrt3 was expressed highly in the gill, muscle and brain, at 40dph (day post hatching) during early development and at stage V in the testis during gonadal development. All fish Dmrts except Dmrt5 were found in the M. amblycephala genome. The observed expression patterns of these Dmrts in developing embryos and larvae, as well as different adult organs indicate conserved sexual or extragonadal functions of the Dmrts through evolution.

Keywords: Alternative splicing; DM domain; Dmrt2a; Dmrt2b; Dmrt3; Gonadal development; Relative expression.