Molecular cloning and expression analysis of the mstn and myod genes in the hybrids derived from Megalobrama amblycephala × Xenocypris davidi Bleeker.

The hybrids (BY) derived from blunt snout bream (Megalobrama amblycephala, BSB, ♀) and Bleeker’s yellow tai (Xenocypris davidi Bleeker, YT, ♂) have a fast growth rate and body thickness. However, the molecular mechanisms underlying the growth advantage of BY are still unclear. MSTN, a member of the TGF-β superfamily, is a negative regulator of muscle growth and development. MYOD, a member of the myogenic regulatory factor family (MRFs), is a positive regulator of muscle growth and development. MSTN and MYOD interact to coregulate muscle growth and development. In this study, we cloned the full-length cDNAs of mstn and myod in BY, analyzed differential expression of the two genes in muscle of BY and its parents, and observed the localization of the two genes during embryonic development of BY. Multiple sequence alignment of amino acids and phylogenetic analysis showed that mstn and myod were highly conserved in BY, BSB, YT, and other carp family fishes. Quantitative Real-time PCR (qRT-PCR) showed that mstn and myod were primarily expressed in muscle of BY, and there were significant differences in the expression of the two genes in the red and white muscles of BY, BSB, and YT at different age. The results of in situ hybridization of embryos showed an overlap in the temporal and spatial expression of mstn and myod in BY embryo development, suggesting that the two genes might interact to co-regulate embryo growth and development. This study provides a theoretical basis for further research on the mechanisms of mstn and myod in muscle growth of hybrid fishes. [ABSTRACT FROM AUTHOR]