dominant alleles determine pheomelanic phenotypes, whereas recessive alleles cause black coat colour with a few exceptions. Mutations at the Agouti locus have, in general, opposite models of action, i.e. Dominant alleles at the Extension locus induce black pigmentation, whereas recessive alleles extend the production of pheomelanins, determining red/yellow/pale pigmentation. These loci show epistatic interactions in different mammals. Extension and Agouti are the main loci that affect the relative amount of eumelanin and pheomelanin production in these cells. This diversity is due to the presence, distribution and biochemical activity of the melanocytes in which two types of melanin pigments (eumelanins and pheomelanins, that produce black/brown and red/yellow colours, respectively) are synthesized. In particular, the surprising not complete association of the nonsense mutation (p.Q225X) with red coat colour raises a few hypotheses on the determination of pheomelanic phenotypes in goats that should be further investigated.Ī large number of coat colour phenotypes have been described in different mammalian species. However, they are probably not the only factors. ConclusionĪccording to the results obtained in the investigated goat breeds, MC1R mutations may determine eumelanic and pheomelanic phenotypes. Moreover, the same substitution was present in almost all Maltese goats providing evidence of association between this mutation and black coat colour. The p.267W allele was present in all Murciano-Granadina black goats, whereas it was never identified in the brown ones.
![bioedit create haplotype tree bioedit create haplotype tree](https://i.ytimg.com/vi/aPEKX1B0lHU/hqdefault.jpg)
However, its frequency was only 33%, despite the fact that these animals are completely red. The same allele was identified in the Derivata di Siria breed. However, there was not complete association between the presence of red spots in the face and the presence of this allele in homozygous condition. The Girgentana breed was almost fixed for the p.225X allele. These SNPs were investigated in a larger sample of animals belonging to the six breeds. The stop codon at position 225 should cause the production of a shorter MC1R protein whose functionality may be altered. Five single nucleotide polymorphisms (SNPs) were identified: one nonsense mutation (p.Q225X), three missense mutations (p.A81V, p.F250V, and p.C267W), and one silent mutation.
![bioedit create haplotype tree bioedit create haplotype tree](https://i.ytimg.com/vi/QRtrCvd4puo/hqdefault.jpg)
The whole coding region of the MC1R gene was sequenced in goats of six different breeds showing different coat colours (Girgentana, white cream with usually small red spots in the face Maltese, white with black cheeks and ears Derivata di Siria, solid red Murciano-Granadina, solid black or solid brown Camosciata delle Alpi, brown with black stripes Saanen, white F 1 goats and the parental animals). The Extension locus encodes the melanocortin 1 receptor (MC1R) whose permanent activation, caused by functional mutations, results in black coat colour, whereas other inactivating mutations cause red coat colour in different mammals.
#Bioedit create haplotype tree skin#
Agouti and Extension loci control the relative amount of eumelanin and pheomelanin production in melanocytes that, in turn, affects pigmentation of skin and hair.