Abstract
Tan sheep (Ovis aries), a Chinese indigenous breed, has special curly fleece after birth, especially at one month old. However, this unique phenotype disappears gradually with age and the underlying reasons of trait evolvement are still unknown. In this study, skin transcriptome data was used to study this issue. In total 51,215 transcripts including described transcripts and transfrags were identified. Pathway analysis of the top 100 most highly expressed transcripts, which included TCHH and keratin gene family members, such as KRT25, KRT5, KRT71, KRT14 and others, showed pathways known to be relevant to hair/fleece development and function. Six hundred differentially expressed (DE) transcripts were detected at two different physiological ages (one-month-old with curly fleece and 48-month-old without curly fleece) and were categorized into three major functional groups: cellular component, molecular function, and biological process. The top six functional categories included cell, cell part, cellular process, binding, intracellular, metabolic process. The detected differentially expressed genes were particularly involved in signal, signal peptide, disulfide bond, glycoprotein and secreted terms, respectively. Further splicing isoform analysis showed that the metallothionein 3 isoform was up-regulated in Tan lamb skin, indicating that it may be related to the conformation of curly fleece in Chinese Tan lamb. The hair-related important differentially expressed genes (SPINK4, FGF21, ESRα, EphA3, NTNG1 and GPR110) were confirmed by qPCR analysis. We deduced that the differences existed in expressed transcripts, splice isoforms and GO categories between the two different physiological stages, which might constitute the major reasons for explaining the trait evolvement of curly fleece in Chinese Tan sheep. This study provides some clues for elucidating the molecular mechanism of fleece change with age in Chinese Tan sheep, as well as supplying some potential values for understanding human hair disorder and texture changes.
Highlights
Chinese Tan sheep (Ovis aries) is one of the most important sheep breeds used for production of high quality pelts in China
Expressed transcripts were identified in lamb and adult sheep skin, respectively (Table S3), and there were 50,786 commonly expressed transcripts between two groups
The detailed reads density on each chromosome can be found in the supplementary material (Table S4)
Summary
Chinese Tan sheep (Ovis aries) is one of the most important sheep breeds used for production of high quality pelts in China. It is a short-tailed indigenous sheep breed distributed in northwestern. The lamb pelts from Tan sheep are characterized by a natural white color and a lustrous curly fleece. The curly fleece appears when Tan lambs are one month old. The lamb pelts with curly fleece tend to be thin and light weight, which are well suited for the production of fur coats, carpets, furniture covering, and various forms of handicrafts (Figure 1). The curly fleece disappears gradually with age and the mechanisms behind the phenomenon are still unclear
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