Polymorphism of the Mannose-Binding Lectin Gene (MBL1) in Ukrainian Small and Transboundary Cattle Breeds - Cytology and Genetics

Abstract In recent years, the introduction of genetic methods to create a more disease-resistant livestock of farm animals in breeding practice increased. The studies of the genes responsible for the immune status of the organism (particularly, mannose-binding lectin 1 (MBL1) gene) are of a special importance. The frequencies of alleles and genotypes of the mannose-binding lectin 1 (MBL1) gene in Ukrainian small and transboundary cattle breeds (Lebedyn, Brown Carpathian, Jersey, Ayrshire, and Swiss) were determined by a method of PCR-RFLP testing using the HaeIII restriction enzyme (c.2569 T>C polymorphism). The determination of T- and C-alleles of the MBL1 is of a practical importance since the mannose-binding lectin gene is a candidate for markers of resistance to mastitis. The frequencies of the MBL1 T-allele in the studied breeds vary from 0.27 to 0.47, those of TC-genotypes from 0.13 to 0.4, and those of TT-genotypes from 0.17 to 0.33. In four breeds, a shift in the genetic equilibrium due to an excess of homozygotes was detected. The values of effective alleles in the MBL1 locus in the studied breeds are less than the threshold value, which indicates that the number of effective alleles in the populations for this locus is less than possible. The cow population of the endangered Brown Carpathian breed was the most polymorphic (Na = 1.993). The largest degree of realization of genetic variability was also detected in the Brown Carpathian breed (V = 41.379) (which was grown and kept in the private sector of the mountain area), and the lowest was in the Ayrshire breed (V = 13.236), respectively. The calculation of genetic distances revealed that the Jersey and Lebedyn breeds were the closest, while a maximal genetic distance was registered between animals of the Jersey and Brown Carpathian breeds. The analysis of genetic structure of the studied cattle breeds in Ukraine revealed changes in the frequency of one or another genotype depending on the breed. The results obtained in this study contain important information, which can be used in cattle breeding for resistance to mastitis.