Characterization of the melanocortin-4 receptor gene from Spinibarbus hollandi and the association between its polymorphisms and S. hollandi growth traits

Abstract

The melanocortin-4 receptor gene (MC4R) is a member of the central melanocortin pathway, which influences development, growth, metabolism, and appetite. In this study, MC4R was cloned and characterized in Spinibarbus hollandi. MC4R DNA is composed of 3068 nucleotides with a 978 nucleotide open reading frame encoding a protein of 326 amino acids. Quantitative real-time polymerase chain reaction (PCR) analysis revealed that MC4R messenger RNA was ubiquitously expressed in tissues, with the most transcriptional abundance in brain and gonad, and that the expression level of MC4R was significantly higher in the lightest group than in the heaviest group of S. hollandi. A primary assessment of sequence variability revealed six single nucleotide polymorphisms (SNPs), among which, four were in the promoter (−698A>G, −679C>T, −326C>T, and −202A>G) and two were in the exon (36A>G and 234C>T). Three SNPs, −698A>G, −679C>T, and 234C>T, were significantly associated with growth traits, two of which, −698A>G and −679C>T, were in complete linkage. The other three SNPs showed no significant associations with any of the growth traits. Our data indicated a significant association between genetic variations in the S. hollandi MC4R and growth traits. Accordingly, the SNPs identified in the MC4R could be used as potential genetic markers in future breeding programs for S. hollandi and other fish.