Key Subject Research Fund Of Animal Genetics, Breeding And Reproduction Of Sichuan Agricultural University

Partial Coding sequence(CDS) and 5'untranslated sequence of melanoeortin-4 receptor(MC4R) gene of rabbits was cloned and sequenced for the first time(GenBank Accession Number:EU410480).Single nucleotide polymorphism in the coding sequence of melanoeortin-4 receptor(MC4R) gene was detected by PCR-SSCP and DNA sequencing in 5 breeds including Haerbing white rabbit,Tianfu black rabbit,Belgian hare,ZIKA rabbit and California rabbit,and the effect of genotypes on performance traits was studied by GLM analysis.The results were as follows:Fragment length of melanoeortin-4 receptor gene(MC4R) was 828 bp by cloning and sequencing.It is showed that MC4R gene have high homology among different species including human(NM005912),mice(AY684817),swine(DQ388767),cattle (BC148892),sheep(AF345913) and chicken(AY545058) by Multiple Sequences Alignment(MSA),and nucleotide homology with rabbit is 93%,91%,90%,88%,86%, 84%.respectively.Two genotypes was detected by PCR-SSCP,A/G conversion mutation at base position 237 was found by cloning and sequencing with high frequency in Haerbing white rabbit, Belgian hare and Zika rabbit and low frequency in Tianfu black rabbit and California rabbit.A1A1 genotype and A1 allele frequency was higher than A1A2 genotype and A2 allele for each of meat rabbit breeds.A1A1 genotype and A1 allele were preponderant genotypes and alleles and their frequency were 0.755,0.879 respectively.PIC value of breeds are 0.249 for Haerbing white rabbit,0.057 for Tianfu black rabbit,0.253 for Belgian hare,0.261 for ZIKA rabbit,0.049 for California rabbit,respectively.PIC value of Belgian hare and ZIKA rabbit was higher than 0.25,is medium polymorphism.The rest is low polymorphism.GLM analysis for the effect of genotypes on performance traits demonstrated that A1A2 genetics effect genotypes was significantly associated with body weight, eviscerated weight,Feed conversion ratio and head weight(P＜0.05),but no significant association with cooking loss,liver weight and kidney weight(P＞0.05).The results showed that A/G conversion mutation at base position 237 have significant influence on body weight,eviscerated weight and Feed conversion ratio,the polymorphic loci may be used as molecular markers for improving body weight and carcass quality in meat rabbits, MC4R gene could be a candidate modifier gene that affect or control the body weight and carcass traits of rabbits.