Search

Dominant black pigment synthesis in sheep is caused by alterations of the melanocortin-1 receptor (MC1-R) coding sequence. Using five bovine microsatellite markers we have mapped the sheep MC1-R gene to chromosome 14, corresponding to the location in other mammalian species. The existence of two independent mutations, both causing an amino acid substitution, in distantly related breeds of sheep, support the hypothesis that the observed black pigment synthesis is caused by a mutual effect of the two mutations. As similar mutations are found separately at both locations in dominant black variants of other animal species, it is also possible that any of the two mutations could be sufficient for a partial pigment switch. [ABSTRACT FROM AUTHOR]

The article presents research which focused on the presence of TYRP1 allele in German Shepherd dogs with recessive brown liver color. Topics covered include the involvement of canine tyrosinase-related protein 1 gene in animals' coat color. Also mentioned are the color patterns that could be developed by the allele.

A letter to the editor is presented that discussed the existence of the multihorned character in domestic goats which is associated with split upper eyelid deformity.

Different mutations in the Bone Morphogenetic Protein 15 (BMP15) and the Growth Differentiation Factor 9 (GDF9) genes cause increased ovulation rate and infertility in a dosage-sensitive manner in sheep. They cause increased ovulation rate and twin and triplet births in heterozygotes, and complete primary ovarian failure in homozygotes resulting in total infertility. We are here presenting a novel mutation in the second exon of the ovine BMP15 gene, found in the Spanish breed Rasa Aragonesa. It consists of a 17 bp deletion resulting in displacement of the open reading frame and premature stop codons. As a consequence, nearly 85% of the sequence of the wild type aminoacidic chain in the second exon of the BMP15 pro-protein is modified or suppressed as only the first 45 amino acids are conserved of the 245 original. The mature peptide is lost. The ewes heterozygous for this deletion present very high prolificacy (2.66 lambs/birth) when compared to a mean flock prolificacy of 1.36 lambs. The deletion causes a complete lack of functionality of the second exon of BMP15, comparable to the effect of premature stop codons in other mutations. Therefore, homozygous females for the deletion are expected to present primary ovarian failure. DNA sequence analysis of the GDF9 coding regions detected only a synonymous Single Nucleotide Polymorphism (SNP), apparently not linked to changes in prolificacy.