title: Genetic polymorphisms of the IGF-II gene intron 8 coding region and its association with growth and carcass traits in yak.
abstract: Insulin-like growth factor II (IGF-II) plays a key role in mammalian growth and is involved in stimulating fetal cell division, differentiation, and metabolic regulation. IGF-II is considered a candidate gene for genetic markers of growth and carcass traits. Therefore, in this study, the associations of single nucleotide polymorphisms (SNPs) in the IGF-II gene region with growth and carcass characteristics in five yak breeds were investigated. Two SNPs, G(330)C and A(358)G, were identified by sequencing intron 8 of the IGF-II gene in homozygotes. Two alleles, A and B, and three genotypes, AA, AB, and BB, were identified by polymerase chain reaction. Genotypic frequencies of IGF-II allele B were 0.8623, 0.8936, 0.8535, 0.8676, and 0.8300 for Datong yak, Gannan yak, Tianzhu white yak, Qinghai Plateau yak, and Xinjiang yak, respectively. Allele and the genotype of IGF-II were strongly associated with growth and carcass traits. Least square analysis revealed a significant effect (P < 0.01) of genotypes AA and AB compared with genotype BB on live-weight (at 12, 13-24, and 25-36 months of age), average daily weight gain (P < 0.01) and carcass weight (P < 0.05). Animals with genotype AB had a higher mean rib eye area, and a lower mean yield grade. The results indicated that the IGF-II gene acts by a primarily additive biological mechanism by adding weight independently of skeletal growth.
authors.affiliation: College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.
authors.forename: Y F
authors.initials: YF
authors.lastname: Zeng
authors.forename: X Z
authors.initials: XZ
authors.lastname: Ding
authors.forename: S R
authors.initials: SR
authors.lastname: Cheng
authors.forename: S J
authors.initials: SJ
authors.lastname: Yu
mesh_terms: D000483:Alleles; D000818:Animals; D001823:Body Composition / Q000235:genetics; D001835:Body Weight / Q000235:genetics*; D001947:Breeding; D002417:Cattle / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D002681:China; D005819:Genetic Markers; D014644:Genetic Variation; D005838:Genotype; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008460:Meat / Q000032:analysis; D016133:Polymerase Chain Reaction / Q000662:veterinary*; D020641:Polymorphism, Single Nucleotide; D015430:Weight Gain / Q000235:genetics*
chemical_list: D005819:Genetic Markers; D007335:Insulin-Like Growth Factor II