|Chase, Chadwick - Chad|
Submitted to: Mexican Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2012
Publication Date: 5/1/2012
Citation: Luna-Nevarez, P., Rincon, G., Medrano, J.F., Riley, D.G., Chase, C.C., Jr., Coleman, S.W., Deatley, K.L., Islas-Trejo, A., Silver, G.A., Thomas, M.G. 2012. Identification of one polymorphism from the PAPP-A2 gene associated to fertility in Romosinuano beef heifers raised under a subtropical environment. Mexican Journal of Animal Science. 3(2):185-200. Interpretive Summary: The growth endocrine axis, primarily growth hormone (GH) and insulin-like growth factor (IGF) have been shown to influence reproductive processes. This endocrine axis has been extensively studied for its role in growth, lactation, and adiposity in domestic animals. Chromosome 5 harbors quantitative trait loci (QTL) that have been associated with fertility traits in cattle and the IGF-I gene map to this locus. There at least 6 additional genes that underlie these QTL that are known to influence the endocrine and cell signaling pathways of GH and IGF-I. Likewise, there are numerous other genes and tissues involved in the growth endocrine axis. For example, pappalysin-2 encoded by the pregnancy associated plasma protein A2 (PAPP-A2) gene cleaves IGF binding protein (IGFBP) -4 and -5 from IGF-I and –II. This gene maps to chromosome 16 and single nucleotide polymorphisms (SNP) in this gene are associated with fertility traits in Holstein cattle. The objective of this study was to identify genetic markers (SNP) associated to fertility traits in beef cows raised in a subtropical environment. Seventy-five SNP were identified as useful in an associative genetic study; however, only 7 were polymorphic and unique to the Romosinuano breed. Then DNA were analyzed from 129 Romosinuano heifers to determine genotypes corresponding to each SNP. Analyses identified PAPP-A2 as a significant predictor of reproductive performance and was associated with lower age at first and second calving. In conclusion, these results provide evidence to support PAPP-A2 gene as a candidate gene associated to reproductive performance in young Romosinuano cows raised in the subtropics.
Technical Abstract: The objective of this study was to identify single nucleotide polymorphisms (SNP) associated to fertility in female cows raised under a subtropical environment. Re-sequencing of 9 genes associated to GH-IGF endocrine pathway located in bovine chromosome 5, identified 75 SNP useful for associative genetic studies; however, only 7 resulted as polymorphic and unique to the Romosinuano breed. Then, DNA samples were extracted from 129 Romosinuano beef heifers and used to determine genotypes corresponding to each SNP. Mixed model analysis identified the SNP PAPPA2_3889 as predictor (P < 0.05) of reproductive performance. The allele T was the most favorable allele (P < 0.05), because it was associated with lower age at first calving (-37.1 ± 14.4 d) and age at second calving (-65.43 ± 30.8 d). In the contrast analysis, the linear term resulted as significant and quadratic term as non significant, which suggested an additive effect of the alleles. In conclusion, these results provide evidence to support the PAPP-A2 gene as a candidate gene associated to reproductive performance in heifers and first-calf cows from the Romosinuano breed, raised under a subtropical environment.