A missense mutation in the coding region of the toll-like receptor 4 gene affects milk traits in Barki sheep

Abstract

Objective: Milk production is one of the most desirable traits in livestock. Recently, the toll-like receptor (TLR) has been identified as a candidate gene for milk traits in cows. So far, there is no information concerning the contribution of this gene in milk traits in sheep. This study was designed to investigate the <i>TLR 4</i> gene polymorphisms in Barki ewes in Egypt and then correlate that with milk traits in order to identify potential single nucleotide polymorphisms (SNPs) for these traits in sheep.Methods: A part of the ovine <i>TLR 4</i> gene was amplified in Barki ewes, to identify the SNPs. Consequently; Barki ewes were genotyped using polymerase chain reaction-single strand conformation polymorphism protocol. These genotypes were correlated with milk traits, which were the daily milk yield (DMY), protein percentage (PP), fat percentage (FP), lactose percentage, and total solid percentage (TSP).Results: Age and parity of the ewe had a significant effect (p<0.05 or p<0.01) on DMY, FP, and TSP. The direct sequencing identified a missense mutation located in the coding sequence of the gene (rs592076818; c.1710C>A) and was predicted to change the amino acid sequence of the resulted protein (p.Asn570Lys). The association analyses suggested a significant effect (p<0.05) of the TLR genotype on the FP and PP, while the DMY tended to be influenced as well (p = 0.07). Interestingly, the presence of the G allele tended to increase the DMY (+40.5 g/d) and significantly (p<0.05 or p<0.01) decreased the FP (–1.11%), PP (–1.21%), and TSP (–7.98%).Conclusion: The results of this study suggested the toll-like receptor 4 (<i>TLR4</i>) as a candidate gene to improve milk traits in sheep worldwide, which will enhance the ability to understand the genetic architecture of genes underlying SNPs that affect such traits.

Sequence analysis of TLR4 gene in river buffalo (Egyptian breed) and SNPs association with Mastitis

“…No SNPs were reported in TLR4 exon2 of river buffalo breeds except in the study byTantia et al (2012) who reported a single SNP at position 1341nt. These Genetic variations between breeds of buffaloes can be attributed to environmental and/or genetic factors.The relative high frequency of non-synonymous SNPs in TLR4 detected in the present study was also reported in 11 different cattle breeds(White et al 2003); in Barki sheep(Sallam 2021), and Murrah buffalo (Roldan-Montes et al 2020) is justi ed since the TLR4 gene is a cell-surface pattern-recognition receptor important to recognition of a broad of PAMPs.It is worth mentioning that the reported three SNPs in the putative binding sites of TLR4 promotor region SNP c.1-g 27,. c1.-g.149 and c1.-g.150 has been previously reported in bovine promoter of TLR4 genes {Sharma et al 2006; Wang et al 2009; Mishra et al 2018 ) and in human and mouse TLR4 gene(Rehli et al 2000).…”

The investigation of SNP in SOCS2 gene associated with mastitis resistance, milk composition, and quality in Awassi sheep.

“…Abousoliman (2021) carried out a genome-wide association study in the Egyptian Burki sheep breed and identified genomic regions in the important genes ABHD5, TBC1D1, KLF3, NUB1, and SLC5A8 for milk yield and other important regions in the genes FBLN1 and PPARA related to milk quality traits. Furthermore, Sallam (2021) identified a significant missense mutation rs592076818 in the TLR4 gene and concluded that the TLR4 gene can serve as a target for improving milk yield and milk quality characteristics in sheep worldwide. Sutera (Sutera et al 2021) found significant SNPs related to fat yield, protein percentage, and milk yield the SNP were identified in the OAR region of the chromosomes 2, 3, and 20 of the Valle del Sheep.…”

Genetic profiling of HSP70 gene in local Iraqi goats

“…Depending on their type, mutations may affect transcription, translation, and mRNA transportation (Goymer, 2007). Conversely, missense mutations can damage the protein, make it nonfunctional (Minde et al, 2011), or sometimes enhance its action, indicating that they are beneficial to the animal as a whole (Sallam, 2021).…”