Association Of Polymorphisms Of CD36, KEAP1Gene With Body Measurements And Meat Quality Traits In Qinchuan Cattle

Fatty acid translocase, CD36(cluster of differentiation36) is a membrane glycoprotein,belongs to class B scavenger receptor, present on skeletal muscle, cardiac muscle, fat, liver. Itis involved in metabolism, atherosclerosis, angiogenesis, immunity. CD36plays an importantrole in lipid metabolism and obesity related complications. As the upstream regulatory gene ofCD36, Nrf2(nuclear factor erythroid2-related factor2), which suppressed, is bound toKEAP1(Kelch-like ECH-associate protein1) in the cytoplasm in the physiological state.Electrophilic and oxidative stress can cause dissociation of Nrf2from the KEAP1/Nrf2complex. Consequently, Nrf2can now accumulate, translocate to the nucleus, then activated,and regulate expression of CD36gene.This research treat CD36and KEAP1gene as candidate gene. In this study,578Qinchuan heifers from18to24month old under similar feeding conditions were randomlyselected. Direct DNA sequencing and polymerase chain reaction-restriction fragment lengthpolymorphism (PCR-RFLP) methods were used to genotype the polymorphisms in CD36gene. The polymorphisms of bovine CD36gene and their associations with bodymeasurement traits and meat traits were analyzed. The aims of the study was to researchpolymorphism of CD36and KEAP1and analyze its effect on body measurement traits andmeat traits in Qinchuan cattle, then find molecular breeding methods of improving bodymeasurement traits and meat traits in Qinchuan cattle. The main results of our study are asfollows:1. In CD36gene, One insertion mutation g.90356indelCTAATTTG (intron5) of eightbases and three SNPs g.90702C>T (intron6), g.91837A>G (intron7) and g.92968A>G (exon8, aa. Asn>Asp) were detected, named SV1, SV2, SV3and SV4respectively. Statisticalanalysis showed that SV1, SV2and SV3were moderate polymorphism, but SV4was lowpolymorphism. All the four mutation sites met Hardy-Weinbery. Further, the linkagedisequilibrium and haplotyes were analyzed among the four loci, suggested that SV1and SV2were complete linkage, SV1-SV2and SV3were strong linked, and SV4was little linked withSV1-SV2and SV3respectively. Interestingly, haplotype of ITA was dominant (withfrequency of60.4%). Except differentiation of EMD at SV4, the result of association analysis showed that the different genotypes of single and combined site were all significantly orextremely significantly associated with meat traits of Qinchuan cattle, and the individualswith combined genotype IITTAG had a lower IFC than that of the individuals with combinedgenotype IITTAG (P<0.05), and combined genotype WWCCAA (P<0.01).(Conclusion) Asthe result showed, CD36gene had a significant effect on meat trait in Qinchuan cattle, andreducing the ratio of individuals with combined genotype IITTAG may be a method toimprove meat traits.2. In KEAP1gene, three SNPs g.3126C>T (exon1, aa. Ala Ala), g.6326T>C (exon2,aa. Ala Ala) and g.6335C>G (exon2, aa. Pro Pro) were detected, named KV1, KV2andKV3respectively. Statistical analysis showed that KV1was low polymorphism, but KV2andKV3were moderate polymorphism. All the three mutation sites met Hardy-Weinbery. Further,the linkage disequilibrium and haplotyes were analyzed among the three loci, suggested thatKV1was little linked with KV2and KV3respectively. KV2and KV3were strong linked.Interestingly, haplotype of CTC was dominant (with frequency of50.6%). The result ofassociation analysis showed the differentiation of BL and IFC at KV1, the differentiation ofHG at KV2, the differentiation of BFT at KV3. The individuals with combined genotypeCTTCCG had a higher EMA than that of the individuals with other combined genotypes(P<0.05)(P<0.01). As the result showed, KEAP1gene had a significant effect on meat traitin Qinchuan cattle, and reducing the ratio of individuals with combined genotype CTTCCGmay be a method to improve meat traits.