GLIS1, a potential candidate gene affect fat deposition in sheep tail

Abstract

Fat deposition in sheep tails is as a result of a complicated mechanism. Mongolian sheep (MG) and Small Tail Han sheep (STH) are two fat-tailed Chinese indigenous sheep breeds while DairyMeade and East Friesian (DS) are two thin-tailed dairy sheep breeds recently introduced to China. In this study, population genomics analysis was applied to identify candidate genes associated with sheep tails based on an in-depth whole-genome sequencing of MG, STH and DS. The selective signature analysis demonstrated that GLIS1, LOC101117953, PDGFD and T were in the significant divergent regions between DS and STH-MG. A nonsynonymous point mutation (g.27807636G>T) was found within GLIS1 in STH-MG and resulted in a Pro to Thr substitution. As a pro-adipogenic factor, GLIS1 may play critical roles in the mesodermal cell differentiation during fetal development affecting fat deposition in sheep tails. This study gives a new insight into the genetic basis of species-specific traits of sheep tails.

Keywords: Fat tail; GLIS1; Mongolian sheep; PDGFD; Population Genomics.

Fig. 1

Selective-sweep analysis by comparing genomes between thin-tailed DS (dairy sheep, DairyMeade and East Friesian) and fat-tailed STH–MG (Small Tail Han sheep and Mongolian sheep). (a) Distribution of population differentiation index ($F_{\mathrm{ST}}$, top panel) and the lineage-specific branch length (LSBL, bottom panel) between DS and STH–MG in a 50 kb sliding window with a 25 kb step increment across all autosomes. (b) π and LSBL values around the genomic region on chromosome 1 (from 27.4 to 28.4 Mb) between DS and STH–MG populations. GLIS1 is located in this genomic sweep region. The red, green and blue cells represent DS, STH and MG population, respectively. (c) Haplotype pattern of the selective-sweep region. Haplotype pattern in a region defined by SNPs that are at a high frequency in DS and at a low frequency in STH–MG. Each column is a polymorphic genomic location, each row is a phased haplotype, and the colored column on the left denotes the population identity of the individuals. The reference/alternative allele is indicated in light yellow/green. (Color figure online)

Fig. 2

Alignment of the amino acid sequences of GLIS1 protein in different mammals. Positions in which the amino acids differ are highlighted in grey