Association of a single nucleotide polymorphism in akirin 2 gene with marbling in Japanese Black beef cattle

A SNP in the 3' untranslated region of the AKIRIN2, referred to as c.*188G>A, was the only difference detected between high- and low-marbled steer groups. The SNP was associated with marbling in 3 experiments using 100 sires (P = 0.041), 753 paternal half-sib progeny steers from 4 sires heterozygous for the c.*188G>A (P = 0.005), and 730 paternal half-sib progeny steers from 3 sires homozygous for the A allele at the c.*188G>A (P = 0.047), in Japanese Black beef cattle. The effect of genotypes of the SNP on subcutaneous fat thickness was not statistically significant (P > 0.05).These findings suggest that the AKIRIN2 SNP polymorphism is associated with marbling and may be useful for effective marker-assisted selection to increase the levels of marbling in Japanese Black beef cattle.Generally, marbling means the amount of intramuscular fat [1]. In Japan, marbling is characterized as the amount and distribution of intramuscular fat in a cross section of musculus longissimus muscle, and called Shimofuri [1]. High levels of such marbling improve the palatability and acceptability of beef by affecting the taste and tenderness of the meat [2-4]. Because of the importance of marbling on the economics of beef production, there is great interest in gaining a better understanding of the molecular architecture of marbling and in generating new opportunities for more effective marker-assisted breeding.We have previously undertaken differential-display PCR (ddPCR) in low-marbled and high-marbled steer groups at 8, 10, 12, and 14 months of age, encompassing the time that marbling starts to appear, to explore genes showing marbling-associated expression changes in musculus longissimus muscle [5]. Among the detected genes, the c17-25 expressed sequence tag (EST) showed higher expression levels in low-marbled steer group than in high-marbled steer group in the middle and late stages of the test period [5]. We have also located the c17-25 EST within genomic region of a quantitative t