Investigation of polymorphism of DGAT۱ gene and its association with body size and tail dimensions traits in Sanjabi sheep

Background and Aim: DGAT۱ is a microsomal enzyme that accelerates the final step of synthesis of triglycerides, namely conversion of diacylglycerol to triacylglycerol. The aim of this study was to identify mutations in DGAT۱ gene and their relationship with body size traits and dimensions tail in Sanjabi rams.Methods: Blood samples from ۹۶ rams were taken and tail length, tail width, tail circumference, body length, body width and height were simultaneously recorded. DNA was extracted from blood and a pair of specific primers was used to amplify a ۸۲۴ bp fragment including of exons ۱۳ to ۱۷ of the DGAT۱ gene. By sequencing for some samples, it was found that three mutations C۸۵۳۹T, C۸۵۲۲T and T۸۳۵۷G have occurred in exon ۱۷ and intron ۱۶ regions of the gene. Therefore, PCR products were digested with AluI, Bsh۱۲۳۶۱ and Adel restriction enzymes in order to genotype all animals in these regions. The collected data was analysed using SAS software and Proc GLM with significant level of ۰.۰۵ to show significant differences.Results: The results of AluI digestion for exon ۱۷ of C۸۵۳۹T showed two CC and CT genotypes with frequencies of ۰.۷۶ and ۰.۲۴, respectively. Digestion of PCR products by BSH ۱۲۳۶۱ restriction enzyme for exon ۱۷ of C۸۵۲۲T position showed two CC and CT genotypes with frequency of ۰.۹۱and ۰.۰۹, respectively. Adel restriction enzyme for Intron ۱۶ T۸۳۵۷G also revealed three TT, TG and GG genotypes with frequencies of ۰.۷۰, ۰.۲۹, ۰.۰۱, respectively. The results of assosiation analyse showed that there was no significant relationship between different genotypes of DGAT۱ and body size traits (P <۰.۰۵). However, there was a significant relationship between genotypes of C۸۵۲۲T mutation and tail length (P <۰.۰۵). The animals with CC genotype had the highest tail length scale compared to CT genotype (P <۰.۰۵). The results also showed that the polymorphism in TG۳۵۷G locus of DGAT۱ gene was significantly correlated with tail length and tail length as animals with GG genotype had the highest tail length compared to other genotypes (P> ۰.۰۵), and the animals with TT genotype had the highest tail width compared to other genotypes (P> ۰.۰۵).Conclusion: In this research, investigation of genetic polymorphisms at the DGAT۱ gene showed that this candidate gene can used as one useful tool in sheep breeding and selection programs but it seems that more studies with more samples on other sheep breeds are necessary to confirm results of this research.

Keywords:

DGAT۱ , Sanjabi sheep , polymorphism , body size , PCR-RFLP