Lack of haplotype structuring for two candidate genes for trypanotolerance in cattle

Abstract

Bovine trypanotolerance is a heritable trait associated to the ability of the individuals to control parasitaemia and anaemia. The INHBA (BTA4) and TICAM1 (BTA7) genes are strong candidates for trypanotolerance-related traits. The coding sequence of both genes (3951 bp in total) were analysed in a panel including 79 Asian, African and European cattle (Bos taurus and B. indicus) to identify naturally occurring polymorphisms on both genes. In general, the genetic diversity was low. Nineteen of the 33 mutations identified were found just one time. Seventeen different haplotypes were defined for the TICAM1 gene, and 9 and 12 were defined for the exon 1 and the exon 2 of the INHBA gene, respectively. There was no clear separation between cattle groups. The most frequent haplotypes identified in West African taurine samples were also identified in other cattle groups including Asian zebu and European cattle. Phylogenetic trees and principal component analysis confirmed that divergence among the cattle groups analysed was poor, particularly for the INHBA sequences. The European cattle subset had the lowest values of haplotype diversity for both the exon1 (monomorphic) and the exon2 (0.077 ± 0.066) of the INHBA gene. Neutrality tests, in general, did not suggest that the analysed genes were under positive selection. The assessed scenario would be consistent with the identification of recent mutations in evolutionary terms.

Differences in genetic structure assessed using Y‐chromosome and mitochondrial DNA markers do not shape the contributions to diversity in African sires

“…The interest in the preservation of West African cattle usually centres on their unique ability of tolerance to trypanosomosis and the increasing interest in the ascertainment of the genetic basis of this trait (Álvarez, Pérez‐Pardal, Traoré, Fernández, & Goyache, ). Animal trypanosomosis is a major obstacle to the development of sustainable livestock production in Africa.…”

“…In contrast, subgroup WA1 took unfavourable contributions to mtDNA diversity (0.3% for gGD T and À1.0% for C T 12 ).This was probably caused by the relatively small sample size of the resulting WA1 group causing stochastic bias in a scenario of no genetic structuring. The interest in the preservation of West African cattle usually centres on their unique ability of tolerance to trypanosomosis and the increasing interest in the ascertainment of the genetic basis of this trait ( Alvarez, P erez-Pardal, Traor e, Fern andez, & Goyache, 2016). Animal trypanosomosis is a major obstacle to the development of sustainable livestock production in Africa.…”

“…Breeding practices aiming at increasing the size of taurine cattle have made cross-breeding with zebu cattle frequent. This unsupervised breeding policy is leading to a dilution of trypanotolerance in West African cattle ( Alvarez et al, 2014;Traor e et al, 2015Traor e et al, , 2016.…”

“…African cattle are well known to show large morphological differences even between neighbouring subpopulations. This can be partially explained by the intermingled presence of Bos taurus (taurine), Bos indicus (zebu) and sanga (taurine x zebu crosses) cattle in the same areas (Traor e et al, 2015(Traor e et al, , 2016. However, genetic differences in African livestock are usually found to be linked to geographic distance (Hanotte et al, 2002;Traor e et al, 2012) rather than to morphological differences or expected different origin.…”

Evolving anti-disease strategies from biochemical pathogenesis of african trypanosomiasis

“…[27][28][29] Further details on the genetic basis of trypanotolerance across various species are available in a recent review by Yaro et al, 24 and the limitations of genetic studies with regard to their application in genomic selection are also reviewed by Meuwissen et al, 30 offering insights into improved genomic selection in animal breeding.…”