Allelic variation of melanocortin-1 receptor locus in Saudi indigenous sheep exhibiting different color coats.

Ahmed H Mahmoud,Ashraf M Mashaly,Ahmed M Rady,Khalid M Al-Anazi,Amgad A Saleh

doi:10.5713/ajas.16.0138

Ahmed H Mahmoud, Ashraf M Mashaly + Show 3 more

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https://doi.org/10.5713/ajas.16.0138

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Abstract

ObjectiveThis study was designed to characterize the DNA polymorphisms of the melanocortin-1 receptor (MC1R) gene in indigenous Saudi Arabian sheep breeds exhibiting different color coats, along with individuals of the Sawaknee breed, an exotic sheep imported from Sudan.MethodsThe complete coding region of MC1R gene including parts of 3′ and 5′ untranslated regions was amplified and sequenced from three the indigenous Saudi sheep; Najdi (generally black, n = 41), Naeimi (generally white with brown faces, n = 36) and Herri (generally white, n = 18), in addition to 13 Sawaknee sheep.ResultsFive single nucleotide polymorphisms (SNPs) were detected in the MC1R gene: two led to nonsynonymous mutations (c.218 T>A, p.73 Met>Lys and c.361 G>A, p.121 Asp>Asn) and three led to synonymous mutations (c.429 C>T, p.143 Tyr>Tyr; c.600 T>G, p.200 Leu>Leu, and c.735 C>T, p.245 Ile>Ile). Based on these five SNPs, eight haplotypes representing MC1R Ed and E+ alleles were identified among the studied sheep breeds. The most common haplotype (H3) of the dominant Ed allele was associated with either black or brown coat color in Najdi and Sawaknee sheep, respectively. Two other haplotypes (H6 and H7) of Ed allele, with only the nonsynonymous mutation A218T, were detected for the first time in Saudi indigenous sheep.ConclusionIn addition to investigating the MC1R allelic variation in Saudi indigenous sheep populations, the present study supports the assumption that the two independent nonsynonymous Met73Lys and Asp121Asn mutations in MC1R gene are associated with black or red coat colors in sheep breeds.

Highlights

Genetic variability assessment within and among different sheep breeds is essential to develop a successful breeding program for selecting ewes that express superior production traits, e.g. those concerning meat, milk and wool production [1]
Five single nucleotide polymorphisms (SNPs) were detected in the melano cortin-1 receptor (MC1R) complete open reading frame (ORF; 954 bp)
When the MC1R receptor is bound by its agonist, alpha melanocyte-stimulating hormone (α-MSH), the intracellular www.ajas.info 157 levels of cyclic adenosine monophosphate are elevat ed through a G-protein signaling pathway and the black/brown eumelanin is produced [18]

Summary

Introduction

Genetic variability assessment within and among different sheep breeds is essential to develop a successful breeding program for selecting ewes that express superior production traits, e.g. those concerning meat, milk and wool production [1]. Saudi Arabia has three native sheep breeds, namely Najdi, Naeimi, and Herri. The Najdi and Naeimi sheep are fat-tailed, adaptable to prevailing adverse environments and are considered the breeds of choice among Saudi consumers [2]. The Herri sheep breed that has noticeable adaptability to prevailing ad verse environments is an excellent indigenous breed in Saudi Arabia. The genetic determinants of coat color in farm animals, including sheep, are critical for breed recognition and fiber production. Coat color in farm animals is divergent and bears significant biological and economic impacts [3,4]. In a large number of mammalian species, the coat color diversity is mainly determined by the relative amount of the two basic melanins, eumelanin

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