Genetic polymorphism of the melatonin receptor (MTNR1A) gene in populations of fine-fleece sheep breeds in Bulgaria

Milena Bozhilova-Sakova, Ivona Dimitrova

Abstract: In the present study was investigated the single nucleotide polymorphism in exon II of the melatonin
receptor (MTNR1A) gene in a total of 90 individuals representing three fine fleece sheep breeds:
Caucasian Merino, Ascanian Merino and Karnobat Merino. By means of PCR-RFLP analysis two allele
variants of MTNR1A gene (C and T) and three genotypes (CC, CT and TT) have been identified.
The obtained genotype frequencies of alleles C and T in the investigated sheep breeds were: 0.60 and
0.40 in Caucasian Merino sheep, 0.47 and 0.53 in Askanian Merino sheep, 0.60 and 0.40 in Karnobat
Merino sheep, respectively. The genetic diversity at MTNR1A gene was with the highest value in the
population of Ascanian Merino (Ho = 0.533 и He = 0.498). The lowest coefficient of inbreeding (Fis
= -0.070) was also observed in this group and it was in correspondence with HWE equilibrium (p =
0.4). The frequency of mutant allele T was higher (0.53) than the wild allele C (0.47). In Caucasian and
Karnobat Merino breeds the allele frequencies were the same – 0.60 and 0.40 for allele C and allele
T, respectively. Despite the same allelic frequencies, the two breeds had different distributions in the
genotype frequencies, with the most significant difference in the heterozygous genotype CT – 0.40
for Caucasian Merino and 0.27 for Karnobat Merino. The population of Karnobat Merino sheep breed
was not consistent with HWE with p = 0.02. The results in this study showed polymorphism in exon II
of the ovine MTNR1A gene in all tested breeds. Due to that fact, it could be concluded that this gene
is suitable for genetic marker.

Keywords: MTNR1A gene; PCR; polymorphism; reproduction; RFLP; sheep

Date published: 2022-06-28