Abstract: Researchers observed that the MC1R genotype of Korean native cattle with dark muzzle was e/e or E+/e while the genotype of Korean native cattle with light muzzle was E+/E+ which is a variant of the MC1R genotype in the Korean native cattle. However, 2 genetic variations, E+/e with 4 bands of 174, 207, 328 and 535 bp and E+/e with 3 bands of 174, 207 and 328 bp were identified in Korean brindle cattle. The dark muzzle in Korean native cattle is formed by eumelanin production through MC1R expression which was higher in the melanocyte region of the tissue in Korean native cattle with light muzzle and Korean brindle cattle. However, in Korean brindle cattle while MC1R expression in the melanocytes of tissues and in total mRNA was not higher than in Korean native cattle with dark muzzle, β-catenin formation which affects MITF production was high. High expression of TYR and DCT, the 2 most important factors to increase eumelanin synthesis, increased dark muzzle formation.
Sang-Hwan Kim and Jong-Taek Yoon, 2013. Changes in Melanogenesis-Related Genes by the Variation of MC1R in Dark-Muzzled Korean Native Cattle and Korean Brindle Cattle. Journal of Animal and Veterinary Advances, 12: 1101-1108.