The Polymorphisms Of SIX1and SIX4and Their Association Analysis With Body Measurements And Meat Quality Traits Of Qinchuan Cattle

SIX1and SIX4which belong to SIX home family are evolutionarily conservedtranscription factors. SIX1and SIX4are key factors in the development and differentiation ofskeletal muscle during embryonic period. SIX1and SIX4work together and can directlyregulate related genes in the development of muscle or play a key role through the help ofmyogenic determining factor.Accordingly, in this study487qinchuan cattle were studied. We analyzed the geneticmutations of SIX1and SIX4which play important role in the development of muscle by DNAsequencing, PCR-RFLP and PCR-SSCP. Gene frequencies and polymorphic information werealso revealed in this study. Meanwhile, associations between these mutations and bodymeasurements and meat quality traits were analyzed. We did so to explore the effect of theseSNPs in the hope of finding some DNA markers which significantly affect economiccharacters, so we can provide some basic theory to improve production and meat traits duringmolecular breeding.As followed are some results from this study.Mutation analysis of SIX1and SIX4geneAccording to NCBI, SIX1（GeneID:511371）has2exons. We designed4pairs of primerand no mutation in the2exons of SIX1gene was found after PCR amplification and DNAsequencingAccording to NCBI, SIX4（GeneID:526104）has3exons. We designed5pairs of primerand5mutations in exon2and exon3of SIX4gene were found after PCR amplification andDNA sequencing. These mutations are g.1546A>G, g.1726C>T, g.1886G>T, g.5456G>A andg.5843A>G of which g.1546A>G, g.1726C>T were in exon2and g.1886G>T, g.5456G>Aand g.5843A>G were in exon3. g.1546A>G(Ala>Ala) and g.1726C>T(Asp>Asp) weresynonymous mutations and g.1886G>T(Val>Leu), g.5456G>A(Glu>Lys) andg.5843A>G(Ala>Thr) were missense mutations. Of all the five mutations, there are only twogenotypes and the heterozygous genotypes were mutant, whose frequencies are11.4%、8.2%、 11.0%、15.0%、12.6%respectively. All five mutations in Qinchuan cattle were in low geneticdiversity.2. Association analysis between body measurements and meat quality traits of QinchuancattleNo mutations were found in SIX1gene after DNA sequencingSIX4gene has five mutations including g.1546A>G, g.1726C>T, g.1886G>T,g.5456G>A and g.5843A>GAt the g.1546A>G locus, Qinchuan cattle individuals with genotype AA had greater hipheight than those with genotype AG, and AA had much greater chest depth than those withgenotype AG. However, there was no association between the two genotypes for otherparameters.At the g.1726C＞T locus animals with genotype CC had significantly greater hip height,chest circumference, ultrasound loin muscle area and ultrasound backfat thickness than thosewith genotype CT. Meanwhile significant statistical differences were found in body lengthand chest depth between the two genotypes. However, there was no association between thetwo genotypes for other parameters.At the g.1886C＞T locus, Qinchuan cattle individuals with genotype GG had greaterbody length, chest circumference and ultrasound loin muscle area than those with genotypeGT. However, there was no association between the two genotypes for other parameters.At the g.5456C＞T locus, analysis of the association between the polymorphism andbody measurement traits showed that there was very significant difference between genotypeAG and genotype GG for chest circumference. Significant difference was also found betweengenotype AG and AG for body length, hip height, hip width, chest depth, loin muscle area andbackfat thickness. However, there was no association between the two genotypes for otherparameters.At the g.5483A＞G locus, Qinchuan cattle individuals with genotype AA had greaterand hip height, chest circumference and backfat thickness than those with genotype AG, andAA had much greater body length and chest depth than those with genotype AG. However,there was no association between the two genotypes for other parameters.