Genetic polymorphism in melatonin receptor 1A and arylalkylamine N-acetyltransferase and its impact on seasonal reproduction in Egyptian sheep breeds

Abstract

This study was carried out to detect polymorphisms in the melatonin receptor 1A (MTNR1A) and arylalkylamine N-acetyltransferase (AA-NAT) genes and their association with reproductive traits. Blood samples of 126 animals from three Egyptian sheep breeds were collected. DNA was extracted and subjected to PCR restriction fragment length polymorphism (RFLP) analysis using the RsaI and SmaI enzymes. Two alleles (C and T) and three genotypes (CC, CT and TT) for MTNR1A and for AA-NAT (A and G; GG, GA and AA) were detected. The alleles C and A and the genotypes CT and GA showed the highest frequencies for the MTNR1A and AA-NAT genes, respectively. Association analysis of the MTNR1A single nucleotide polymorphism (SNP) with ewe reproductive traits revealed significant associations in the Ossimi and Rahmani breeds with age at first lambing, and the C allele seemed to be the favorable allele. The results for the AA-NAT SNP demonstrated significant correlations in Ossimi with age at first lambing and litter size and in Rahmani with lambing interval; the G allele seemed to be the desirable allele. In the first conception season, ewes carrying CT exhibited a significantly lower age of first lambing in the unfavorable season. Additionally, GG ewes exhibited a significantly lower age of first lambing in the early favorable season, followed by the unfavorable season. To the best of our knowledge, this is the first study of these associations in Egyptian sheep breeds. In conclusion, the polymorphisms revealed in this study could be used as genetic markers to improve reproductive efficiency during the unfavorable season, and the obtained desirable genotypes could be considered in new genetic selection schemes.

Polymorphisms of the melatonin receptor 1A (MTNR1A) gene influence the age at first mating in autumn-born ram-lambs and sexual activity of adult rams in spring

“…The frequency of the mutant allele G at position g.17355452 G>A of the MTNR1A gene exon II sequence in our study was similar to those found in other sheep breeds [16,[29][30]. Our results, moreover, showed that at the position g.17355458 C>T, the frequency of the T allele was higher than it is in the Sarda breed, but very similar to those in some Indian and Egyptian sheep breeds [31][32][33].…”

Association of melatonin receptor 1 A with litter size in sheep: A review

“… 7 , 21 Ewes’ seasonal reproductive activity is linked to the presence of many polymorphic sites at the MTNR1A locus, which can be found to be variable. 5 , 22 Despite the fact that the ramifications of the MTNR1A gene on reproductive seasonality have only been investigated to a limited extent up until this point, those studies have shown that these effects are tied to three specific mutations discovered in exon II at locations 606, 612, and 706, 7 , 21 only sheep of the Sarda and Aragonese breeds have had the remaining portions of this gene examined. 12 , 13 , 23 – 25 …”

“…It has been noted that in sheep breeds where estrous activity peaks during short days, variations in day length may function as a main factor determining seasonal variations in estrous activity. 5 – 7 In the pineal gland, the indole hormone melatonin (MT) is produced, 8 which is linked to changes in light signals of the external natural environment. 9 – 13 …”

Endocrine disorders and fertility and pregnancy: An update

“…The relationship between melatonin receptors polymorphism and female fertility has been proven (32,(39)(40)(41). There are also numerous reports suggesting a protective effect of melatonin administration on fertility, maintenance of pregnancy and prevention of birth defects in females exposed to cytostatics, insecticides, herbicides and alcohol (42-46), which is directly related to its antioxidant nature.…”