Effect of Selection for Wool Growth on Seasonal Patterns of Yield, Fibre Diameter, and Colour in Romney LinesSeasonal wool growth and associated wool characteristics were measured in a Romney line selected for high fleece weight and an unselected control line in 1990 and 1991. Both had a significant (P < 0.01) decline in wool growth rate in winter compared with summer. The wool growth rate advantage (P < 0.001) of the selected line over the control averaged 19 and 33% for ewes, and 24 and 36% for hoggets, in summer and winter, respectively. Staple strength, yield, and fibre diameter differences were closely associated with wool growth. Colour analysis showed no difference between lines in either brightness (Y) or yellowness (Y - Z). However, both the Y and Z values were lower in spring and summer, while Y - Z was highest in summer. The results suggest that selection for high fleece weight also improves major wool characteristics and reduces the relative winter wool growth decline in Romneys.
- Previous molecular genetic studies of physiology and pigmentation of sheep skin have focused primarily on a limited number of genes and proteins. To identify additional genes that may play important roles in coat color regulation, Illumina sequencing technology was used to catalog global gene expression profiles in skin of sheep with white versus black coat color.
- MicroRNAs (miRNAs) are small, non-coding 21–25 nt RNA molecules that play an important role in regulating gene expression. Little is known about the expression profiles and functions of miRNAs in skin and their role in pigmentation. Alpacas have more than 22 natural coat colors, more than any other fiber producing species. To better understand the role of miRNAs in control of coat color we performed a comprehensive analysis of miRNA expression profiles in skin of white versus brown alpacas.
Characterisation of the Melanocortin-1 Receptor Gene in Alpaca and Identification of Possible Markers Associated with Phenotypic Variations in ColourThe aim of this study was to determine if any correlation exists between melanocortin-1 receptor (MC1R) polymorphisms and skin and fibre colour in alpacas. Primers capable of amplifying the entire alpaca MC1R gene were designed from a comparative alignment of Bos taurus and Mus musculus MC1R gene sequences. The complete MC1R gene of 41 alpacas exhibiting a range of fibre colours, and which were sourced from farms across Australia, was sequenced from PCR products. Twenty-one single nucleotide polymorphisms were identified within MC1R. Two of these polymorphisms (A82G and C901T) have the potential to reduce eumelanin production by disrupting the activity of MC1R. No agreement was observed between fibre colour alone and MC1R genotype in the 41 animals in this study. However, when the animals were assigned to groups based on the presence or absence of eumelanin in their fibre and skin, only animals that had at least one allele with the A82/C901 combination expressed eumelanin. We propose that A82/C901 is the wild-type dominant ‘E’ MC1R allele, while alpacas with either G82/T901 or G82/Y901 are homozygous for the recessive ‘e’ MC1R allele and are therefore unable to produce eumelanin.
- Melanin plays important roles in the formation of animal hair color, the members of TYR gene family participate in the synthesis of melanin. For exploring the relationship between gene expression of alpaca TYR gene family and alpaca's coat color, the relative expression quantity of TYR,TRP1,TRP2 in alpaca of different colors were analyzed by using real-time quantitative PCR in this research. Results showed that the relative expression quantity of TYR,TRP1,TRP2 in Brown alpaca respectively were 13.669,3.417,8.593 times than that in White alpaca, all results were corrected by the household gene. The findings indicated that gene expression level of TYR gene family in Brown alpaca were higher than that in White alpaca, and the gene expression level of TYR gene family were related with phenotype of alpacas' coat color.