Association of swine vertnin (VRTN) gene with production traits in Duroc pigs improved using a closed nucleus breeding system.

Vertnin (VRTN) is involved in the variation of vertebral number in pigs and it is located on Sus scrofa chromosome 7. Vertebral number is related to body size in pigs, and many reports have suggested presence of an association between body length (BL) and meat production traits. Therefore, we analyzed the relationship between the VRTN genotype and the production and body composition traits in purebred Duroc pigs. Intramuscular fat content (IMF) in the Longissimus muscle was significantly associated with the VRTN genotype. The mean IMF of individuals with the wild-type genotype (Wt/Wt) (5.22%) was greater than that of individuals with the Wt/Q (4.99%) and Q/Q genotypes (4.79%). In addition, a best linear unbiased predictor of multiple traits animal model showed that the Wt allele had a positive effect on the IMF breeding value. No associations were observed between the VRTN genotype and other production traits. The VRTN genotype was related to BL. The Q/Q genotype individuals (100.0 cm) were longer than individuals with the Wt/Q (99.5 cm) and Wt/Wt genotypes (98.9 cm). These results suggest that in addition to the maintenance of an appropriate backfat thickness value, VRTN has the potential to act as a genetic marker of IMF.

Overexpression of NUDT7, a candidate quantitative trait locus for pork color, downregulates heme biosynthesis in L6 myoblasts.

While testing a quantitative trait locus (QTL) for pork color in a cross population of pigs from the mating of Large White dams to a Japanese wild boar, our laboratory discovered a candidate gene (NUDT7) that might affect heme biosynthesis in porcine muscle. Therefore, this experiment was designed to test the effect of NUDT7 on heme biosynthesis in cultured myoblasts. Rat L6 myoblasts were transfected with a mammalian expression vector for pig NUDT7 immediately after the induction of cell differentiation, and samples were harvested at 2, 4, 6, and 8 days. Expression of exogenous NUDT7 mRNA was highest on day 4, when the heme content was substantially lower (P<0.01) than that of the control (14.2 vs. 63.9 pmol/10(5) cells). These results suggest that overexpression of pig NUDT7 may be associated with heme biosynthesis downregulation in skeletal muscle, which may partially explain differences in meat color among breeds of livestock.