Genetic polymorphism of the melatonin receptor MT1 gene in four Bulgarian sheep breeds

D. Hristova, S. Georgieva, Ts. Yablanski, S. Tanchev, R. Slavov, G. Bonev
Abstract. The polymorphism of the melatonin receptor MT1 gene, for the first time was investigated on a total of 204 individuals representing four Bulgarian sheep breeds: Local Starozagorska, Local Karnobatska, Breznishka and Sofiiska (Elin-Pelinska). Two genetic variants of MTNRIA gene (C and T) and three genotypes (CC, CT and TT) have been identified using PCR-RFLP analysis. The obtained gene frequencies of MTNRIA C and T in two investigated breeds, were opposite: 0,302 and 0,698 in Local Starozagorska, versus 0,729 and 0,271 in Local Karnobatska, respectively. Similar allele frequencies were found in the other sheep breed: 0,520 and 0,480 in Breznishka and 0,526 and 0,474 in Sofiiska, respectively. The most prevalent genotype at the MTNRIA was CT, with the highest frequency 0,532 in Local Karnobatska, while in Local Starozagorska it was low (0,229). The mean observed heterozygosity was 0.401 and varied in the particular populations between 0.226 (Local Starozagorska) to 0.541 (Local Karnobatska). Generally, the average genetic diversity at MTNR1A was 0.458, with the highest value in Breznishka (0.504). The exact P-values for the separate breeds were obtained and all breeds were in correspondence with HWE equilibrium. The results presented in this study show, clearly polymorphism of the MTNR1A gene with respect to Bulgarian local sheep breeds and thus would be confirm the importance of this gene as a potential DNA marker in marker – assisted selection as well as for preservation genetic diversity of the examined populations.