Molecular characterization of the partial coding sequence (CDS) of the luteinizing hormone receptor (LHR) gene in Indian cattle breeds

Luteinizing hormone receptor (LHR) gene codes for LH receptors in ovaries that are important site for binding of luteinizing hormone (LH), which affects the reproductive physiology in dairy animals. In the present study, partial coding sequence (CDS) including exon 11 (>1100 bp) of LHR gene was cloned and characterized in Sahiwal and Hariana cattle breeds. Sequencing and chromatogram study of LHR Exon 11 sequence showed two heterozygous condition revealed A→G and G→A non-synonymous substitutions at position 107 and 524, respectively, which resulted into substitution of asparagine (N) to aspartic acid (D) and valine (V) to methionine (M) at 36 and 175 amino acid position, respectively. Therefore these two heterozygous conditions identified as NV and DM genotypes in Sahiwal breed. Sequence comparison of LHR exon 11 of Sahiwal (NV and DM) and Hariana showed 98.7% to 100% homology with exotic cattle breeds at nucleotide and amino acid level, respectively. DNA polymorphism was also investigated using HhaI/ PCR-RFLP assay. It showed three types of genotypes namely, TT (303 bp), TC (303, 155, and 148 bp) and CC (155 and 148 bp), where TT genotype was more frequent (45.0%) than TC (42.5%) and CC (12.5%) genotype and frequency of T allele was higher (0.66) than C allele (0.34) in all the screened animals. Chi square (χ2) analysis indicated that all the screened animals were found in Hardy-Weinberg equilibrium. Association analysis revealed no significant association with milk production and reproduction traits.