Abstract
Simple SummaryThe keratin-associated proteins (KAPs) are structural components of cashmere fibres. The human and sheep orthologous gene encoding high-sulphur (HS)-KAP24-1 is now described for the goat species. Our study identified the caprine KAP24-1 gene on goat chromosome 1, and we found that the gene was polymorphic and that variation in the gene affected cashmere fibre diameter.The keratin-associated proteins (KAPs) are structural components of cashmere fibres. The gene encoding the high-sulphur (HS)-KAP24-1 (KRTAP24-1) has been identified in humans and sheep, but it has not been described in goats. In this study, we report the identification of caprine KRTAP24-1, describe variation in this gene, and investigate the effect of this variation on cashmere traits. A search for sequences orthologous to the ovine gene in the goat genome revealed a 774 bp open reading frame on chromosome 1, which could encode an HS-KAP. Based on this goat genome sequence and comparison with ovine KRTAP24-1 sequences, polymerase chain reaction (PCR) primers were designed to amplify an 856 bp fragment that would contain the entire coding region of the putative caprine KRTAP24-1. Use of this PCR amplification with subsequent single-strand conformation polymorphism (SSCP) analysis of the amplicons identified four distinct patterns of DNA bands on gel electrophoresis, with these representing four different DNA sequences (A to D), in 340 Longdong cashmere goats reared in China. The variant sequences had the highest similarity to KRTAP24-1 sequences from sheep and humans, suggesting that they are variants of caprine KRTAP24-1. Nine single-nucleotide polymorphisms (SNPs) were detected in the gene, including four non-synonymous SNPs and an SNP in proximity to the ATG start codon. Of the three common genotypes (AA, AB, and BB) found in these Longdong cashmere goats, cashmere fibres from goats of genotype AA had lower mean fibre diameter (MFD) than did those of genotype AB, and cashmere fibres from goats of genotype AB had lower MFD than did those from goats of genotype BB.
Highlights
The fleece of cashmere goats comprises cashmere, which is the fibre produced by the secondary fibre follicles, and higher-fibre-diameter “guard hairs” that are produced by the primary fibre follicles.As cashmere is a valuable product, it is separated by combing from the guard hairs, which are discarded, and the value of goat fleece is determined by particular cashmere fibre traits
We report the identification of caprine KRTAP24-1, describe variation in this gene, and investigate the effect of this variation on cashmere traits
Fibres collected from the mid-side region of the goats were measured to ascertain the crimped fibre length and the mean fibre diameter (MFD), which was assessed by the Inner Mongolia Agricultural University, Inner Mongolia, China
Summary
The fleece of cashmere goats comprises cashmere, which is the fibre produced by the secondary fibre follicles, and higher-fibre-diameter “guard hairs” that are produced by the primary fibre follicles. As cashmere is a valuable product, it is separated by combing from the guard hairs, which are discarded, and the value of goat fleece is determined by particular cashmere fibre traits. The weight fleece weight and the mean fibre diameter (MFD) are the most valuable of the cashmere traits that can be measured. They, in large part, control the financial return to cashmere producers [1]. It is known that both genetic and environmental factors affect variation in cashmere traits. The identification of genes that regulate cashmere quantity and quality offers some opportunity to improve cashmere production
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