Insulin receptor substrate-1(IRS-1) gene is one member of the Insulin receptor substrate (IRS) gene family, which plays an important role in mediating the growth of skeletal muscle and the molecular metabolism of type 2 diabetes. Here, we cloned a 3,573 bp fragment of the partial CDS sequence of porcine IRS-1 gene by in silicon cloning strategy and RT-PCR method. The porcine IRS-1 gene was assigned to SSC15q25 by using IMpRH. Sequencing of PCR products from Duroc and Tibetan pig breeds identified one SNP in exon 1 of porcine IRS-1 gene (C3257A polymorphisms). Association analysis of genotypes with the growth traits, anatomy traits, meat quality traits and physiological biochemical indexes traits showed that different genotypes at locus 3,257 of IRS-1 have significant differences in carcass straight length in pigs (P = 0.0102 \ 0.05).

The nutrient transportation ability of placenta depends on placental size, vascular density and permeability. Regulation of angiogenesis in the placenta is critical for successful gestation. Placenta vascularity exhibits disparity in different gestation stages and different pig breeds. To investigate the expression of genes related to permeability in the porcine placenta of different gestation stages and breeds, molecular cloning and gene expression analysis of six porcine genes, vascular endothelial growth factor (VEGF), VEGF-R1, VEGF-R2, endothelial nitric oxide synthase (eNOS), vascular endothelial cadherin (CDH5) and b-arrestin2 (Arrb2), were performed in this study. The results demonstrated that from gestation day 33 to day 90, Landrace exhibited significant increase ( P , 0.05) in placental VEGF and Arrb2 mRNA expression. Moreover, expression levels of VEGF, VEGF-R1, VEGF-R2 and eNOS mRNA were higher ( P , 0.01) in the placenta of Erhualian than those in Landrace on day 90 of gestation. In contrast, CDH5 placental mRNA expression level exhibited significant decrease ( P , 0.05) from day 33 to day 90 gestation in Landrace. Erhualian placental CDH5 and Arrb2 expression levels were significantly lower ( P , 0.01) than those in Landrace conceptuses on day 90 of gestation. Our study offered new data on the expression of genes in VEGF signal transduction pathway in porcine placenta.