ABSTRACT: BACKGROUND:In Sus scrofa, methionine sulfoxide reductase B3 (MSRB3) is a crucial candidate gene for ear size, and an important conformational trait of pig breeds. However, challenges in MSRB3 cDNA amplification have prevented further identification of MSRB3 allelic variants influencing pig ear size. RESULTS:We cloned a full-length cDNA sequence of porcine MSRB3 by rapid-amplification of cDNA ends. The 3,765-bp gene contained a 5'-untranslated region (UTR) (190 bp), a coding region (552 bp), and a 3'-UTR (3,016 bp) and shared 84 %, 84 %, 87 %, 86 %, and 70 % sequence identities with human, orangutan, mouse, chicken, and zebrafish, respectively. The gene encoded a 183-amino acid protein, which shared 88 %, 91 %, 89 %, 86 %, and 67 % identities with human, orangutan, mouse, chicken, and zebrafish, respectively. Tissue expression analysis using qRT-PCR revealed that MSRB3 was expressed in the heart, liver, lung, kidney, spleen, ear, muscle, fat, lymph, skeletal, and hypothalamic tissues. Three single nucleotide polymorphisms (SNPs) were identified in MSRB3: c.-735C?>?T in the 5' flanking region, c.2571 T?>?C in the 3'-UTR, and a synonymous mutation of c.484 T?>?C in the coding region. The SNPs c.-735C?>?T and c.2571 T?>?C were significantly associated with ear size in a Large White?×?Minzhu F2 population other than in Beijing Black pigs. Subsequently, at SNP c.-735C?>?T, the mRNA of MSRB3 was significantly higher expressed in ears of individuals with the TT genotype (Minzhu) than those with CC (Large White). CONCLUSIONS:The porcine MSRB3 owned a 3,765-bp full-length cDNA sequence and was detected to express in ear tissue. Two SNPs of this gene were shown to be significantly associated with ear size in a Large White?×?Minzhu intercross population instead of Beijing Black pig population. What's more, the individuals with higher mRNA expression of MSRB3 have larger ear sizes. These results provide useful information for further functional analyses of MSRB3 influencing ear size in pigs.
