An examination of melanogenic traits and TYRP1 polymorphism in Nanping and Romney Marsh sheep breeds

G. Li; G. Li; H. Xiong; H. Xiong; D. Xi; S. Memon; S. Memon; L. Wang; X. Liu; X. Liu; W. Deng; W. Deng

An examination of melanogenic traits and TYRP1 polymorphism in Nanping and Romney Marsh sheep breeds

2018

The effects of mutations of the gene for tyrosinase-relatedprotein 1 (TYRP1) on the black muscles and coat color in Nanpingblack-boned sheep were investigated. Tyrosinase activity and melanin contentin plasma were measured and compared in three random groups of sheep: Nanpingblack-boned (101 heads), Nanping normal (106 heads) and Romney Marsh sheep(82 heads, Ovis aries). Eight exons and their partial flankingregions of the TYRP1 gene were amplified. Six intronic mutations andsix exonic polymorphisms including two non-synonymous mutations [c.203C  >  T(p.A68V) and c.1202T  >  C (p.V401A)] were identified. Using abi-directional polymerase chain reaction allele-specific amplification(bi-PASA) of the mutation c.203C  >  T it was shown that the frequencies ofallele C in the Nanping black-boned, Nanping normal and Romney Marsh sheepwere respectively 0.955, 0.967 and 0.744. For the mutation c.1202T  >  C,the frequencies of allele T in the three populations of sheep wererespectively 0.777, 0.745 and 0.793 as measured using the single-strandconformation polymorphism. When the data from sheep of all three populationswith the CC genotype of SNP c.203C  >  T were pooled, it was found that therewas significantly higher (P  <  0.05) tyrosinase activity, content ofalkali-soluble melanin and ratio of eumelanin : total melanin thanin the plasma of sheep with the CT and TT genotypes. This was not so within eachof the three groups of sheep. No significant effect of the TRYP1genotype on coat color was found. Further studies will be necessary todetermine the cause of the black traits in Nanping black-boned sheep.

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