Genetic Variation and Relationship of N'Dama Cattle Toll-like Receptor 5 with Other Bovine Species

摘要

Toll-like receptor 5 is involved in innate immune responses that are initiated by host pattern recognition receptors (PRRs), which recognize molecular structures of conserved pathogenassociated molecular patterns (PAMPs) expressed by microorganisms especially bacteria. In this study, we sequenced 2577 bp bovine TLR5 in N’Dama cattle and discovered four synonymous mutations with one (C2127T) being shared between the N’Dama and the wild cattle. Sequences of other bovine species including Bos taurus, Bos indicus and Bos javanicus from public domain revealed higher number of non-synonymous mutations 19, 7 and 6 in wild cattle, Bos indicus subspecies and the Bos taurus respectively with a higher ratio of total number of non-synonymous mutations to that of synonymous mutations suggesting that the gene is evolving under adaptive evolution. The results of genetic diversity revealed a combination of high haplotype diversity and low nucleotide diversity which is an evidence of past and rapid demographic expansion from a small effective population size. Haplotype reconstructions, median-joining networks and phylogenetic analysis revealed haplotype sharing among Bos taurus, Bos indicus and their hybrid suggesting retention of conserved ancestral variation that predates subspecies divergence in this immune gene. There is no haplotype sharing between the wild and the domestic cattle, but a close relationship of the wild cattle clade with one of the N’Dama cluster suggesting little exchange of genetic material between these two groups of cattle. This results will facilitate effort towards understanding the relationship between mutations in different bovine species and their involvement in differential susceptibility and or tolerance to various diseases.