Tissues Expression Analysis, Novel SNPS Of The Bovine RXRα Gene And Its Effects On Growth Trait

Retinoid X receptor (RXR) α is a member of the nuclear hormone receptorsuperfamily that mediates the biological effects on several hormones, vitamins, andregulates lipid, glucose and energy metabolism. In this study, the gene expressionprofile was detected in various tissues in Jiaxian red cattle by quantitative real-timePCR. While the polymorphism of the RXRα gene were analyzed by DNA poolssequencing, PCR-RFLP method in Jiaxian red cattle, Nanyang cattle, Luxi cattle,Bohai black cattle, Qinchuan cattle and Gaoyuan yak, a total number of413, andinvestigated their associations with growth traits. To assess whether RXRα gene couldbe efficient molecular markers for marker-assisted selection (MAS), the associationsbetween these SNPs or their combinations with growth traits were evaluated in cattle,which will provide some genetic information for the efficient selection program incattle breeding. The results were as follows:1. Tissue expression profile of RXRα gene in Jiaxian red cattleThe mRNA expressions profile showed that the RXRα gene was predominantlyexpressed in adipose and spleen in Jiaxian red cattle, and moderately expressed inheart, liver, lung, kidney, muscle and testis, with minor expression in rumen. Whilethe mRNA expression of RXRα gene was not detected in intestine.2. The genetic polymorphism of bovine RXRα geneAll of the exons of RXRα gene were detected in six populations. Four SNPs(T12856A, G24539A, T28139C and G28142A) in the coding region and one SNP(T27919A) in the noncoding region were discovered. Among them there were threemissense mutations that introduced amino acid changes. One SNP (G24539A)resulted in amino acid substitution that is Ala/Thr. The T28139C locus changedamino acid, Val to Ala and G28142A locus resulted to Arg/Lys. The T12856A,G24539A and G28142A loci were low polymorphism in Jiaxian cattle population andmoderate polymorphism in Bohai black cattle and Nanyang cattle, while T27919Aand G24539A loci were low polymorphism in Luxi cattle and moderate polymorphism in Nanyang and Qinchuan cattle.The results through linkage disequilibrium analysis showed that it was in stronglinkage disequilibrium in five yellow cattle (r2>0.33) for T12856A and G24539A,T12856A and T28139C, T12856A and G28142A, T27919A and T28139C, T27919Aand G28142A loci, while it was in weak linkage disequilibrium (r2<0.33) forT12856A and T27919A, G24539A and T27919A, G24539A and T28139C, G24539Aand G28142A, T28139C and G28142A, respectively.3. The association analysis between the genetic polymorphism of bovine RXRα geneand the growth traitsAssociation between single locus and growth traits revealed that the individualswith TA genotype had greater abdominal circumference and hipbone width than thosewith TT genotype at T12856A locus (P <0.05) in Luxi cattle. At G24539A locus, theindividuals with GA genotype had greater abdominal circumference, body weight andheart girth than those with AA genotype in Luxi cattle (P <0.05). At T27919A locus,the individuals with TA genotype had greater abdominal circumference than thosewith AA genotype in Luxi cattle (P <0.05). The individuals with TC genotype hadgreater body weight and heart girth than those with CC genotype at T28139C locusfor Luxi cattle (P <0.05). At G28142A locus, the individuals with AA genotype hadgreater abdominal circumference than those with GG genotype in Luxi cattle (P <0.05). For Jiaxian red cattle, the individuals with AA genotype had greater bodyheight, heart girth and hip width than those with TT genotype at T12856A locus (P <0.05). At G24539A locus, the individuals with GA genotype had greater body length,abdominal circumference and hip height than those with GG genotype (P <0.05). AtT27919A locus, the individuals with AA genotype had greater body length and bodyweight than those with TT genotype (P <0.05). At T28139C locus, the individualswith TC genotype had greater abdominal circumference than those with TT genotype(P <0.05). At G28142A locus, the individuals with GG genotype had greater heartgirth than those with AA genotype (P <0.05).