Genetic variability of bovine GHR, IGF-1 and IGFBP-3 genes in Indian cattle and buffalo

The identification of genetic polymorphisms in the genes that play a crucial role in regulatiing growth and development of livestock enables us to evaluate the biological similarities and to acquire a better perspective of quantitative traits. The present study was undertaken to characterize genetic variability in the bovine growth hormone receptor (GHR), insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3) genes among Bos indicus (Malnad Gidda, Khillar), Bos taurus (Holstein Friesian, Jersey) cattle and Asian water buffalo Bubalus bubalis (Murrah, Surti) using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis. These polymorphisms were confirmed by direct sequencing. The comparative gene sequence analysis in cattle and buffalo breeds revealed 18 single nucleotide polymorphisms (SNPs) across different loci. Eight SNPs were detected in the bovine growth hormone receptor (GHR) gene, of which four were found in the promoter region and four in the exon 4 region. In the IGF-1 gene, two SNPs were observed in the 5ˈUTR, three SNPs in the intron 3 region and two SNPs in the coding region of exon 4. Three SNPs were detected in the exon 2 region of the bovine IGFBP-3 gene. The frequency of rare alleles observed in the present study ranged from 0.04 to 0.16. The present results revealed high levels of genetic variability in the GHR, IGF-1 and IGFBP-3 genes in cattle and buffalo reared in India. Keywords: PCR-SSCP, genetic polymorphism, cattle, buffalo