Influence of leptin gene polymorphism on marbling percentage in Simmental cross breed cattle (Bos Taurus)

Abstract

Single nucleotide polymorphisms (SNP’s) are the most frequent type of variation in the genomes of mammals, and they provide powerful tools for genetic selection. Therefore, they can be used to improve different quality traits by means of marker identification. The objective of this study was to detect polymorphisms in the obese gene of Chinese Simmental bulls, that are associated with variations in intramuscular fat content. Therefore, DNA from 51 Simmental bulls was collected and sequenced. Sequenced products were analyzed for SNP’s and compared to the known bovine genome. Five SNP's were found in the leptin gene. There was a C-T substitution at location 14697 of leptin gene exon 2 resulting in a change in amino acid from Arganine (R) to Cysteine (C). In exon 3 an A-G substitution at location 18095, C-T substitution at location 18268, T-C substitution at 19130 and a G-T substitution at 19263 has been determent, however, because these SNP's are located in the non-coding region of the ob-gene, mutations do not result in amino acid substitutions. Two different statistical analyses were carried out: associations of both genotype and haplotypes with intra muscular fat content were evaluated. No significant differences in intra muscular fat content and individual leptin SNP genotypes were observed, nor was there any tendency towards significance. Also, there was no significant effect between different genotypes. These results are comparable as well as conflicting with similar published studies. Therefore, more research is needed before a reliable answer can be formulated for the of leptin gene SNP's in relation to IMF.