Expression analysis and single-nucleotide polymorphisms of SYNDIG1L and UNC13C genes associated with thoracic vertebral numbers in sheep (Ovis aries)

Abstract

The objective of the current study was to analyze expression levels of synapse differentiation inducing 1-like (SYNDIG1L) and unc-13 homolog C (UNC13C) genes in different tissues, while single-nucleotide polymorphisms (SNPs) of two genes were associated with multiple thoracic vertebrae traits in both Small-tailed Han sheep (STH) and Sunite sheep (SNT). The expression levels of SYNDIG1L and UNC13C were analyzed in the brain, cerebellum, heart, liver, spleen, lung, kidney, adrenal gland, uterine horn, longissimus muscle, and abdominal adipose tissues of two sheep breeds with different thoracic vertebral number (TVN) sheep (T13 groups and T14 groups) by real-time quantitative polymerase chain reaction (RT-qPCR). Meanwhile, the polymorphisms of UNC13C gene g.52919279C $>$ T and SYNDIG1L gene g.82573325C $>$ A in T14 and T13 were genotyped by the Sequenom MassARRAY^® SNP assay, and association analysis was performed with the TVN. The results demonstrated that UNC13C gene was extensively expressed in 11 tissues. The expression of UNC13C gene in longissimus muscle of T14 groups of STH was significantly higher than that of T13 groups ( $P<0.05$ ). SYNDIG1L gene was overexpressed in brain and cerebellum tissues, and the expression level of UNC13C gene in the brain and cerebellum of T13 groups in SNT was significantly higher than that of T14 groups ( $P<0.01$ ). Association analysis showed that SNPs found in the UNC13C gene had no significant effects on TVN for both two genes. The polymorphism of SYNDIG1L g.82573325C $>$ A was significantly correlated with the TVN in both STH ( $P<0.05$ ) and SNT ( $P<0.01$ ). Taken together, the SYNDIG1L gene was related to thoracic vertebral development, and this variation may be potentially used as a molecular marker to select the multiple thoracic vertebrae in sheep.

Figure 1

Genotyping results. (a) Scatter plot of SYNDIG1L genotyping results. (b) Scatter plot of UNC3C genotyping results.

Figure 2

Results of expression level of UNC13C and SYNDIG1L genes in STH and SNT with different TVNs. (a) The comparison of expression levels of UNC3C between SNT and STH. (b) The comparison of expression levels of SYNDIG1L between SNT and STH. The significant results with a $p$ value lower than 0.05 are given one asterisk ($\ast$).