Studies On Cloning And Polymorphic Analysis Of Melanocortin Receptor-4 Gene In Goose

Melanocortin receptor-4(MC4R)can cooperate with leptin,neuropeptide Y and melanocyte-stimulating hormone to regulate body weight and feeding in mammals.In poultry,MC4R gene expressing had a close relationship with body fat depositing.In this study,MC4R gene which related to fat depositing was selected as candidate gene.By genome comparison,the goose MC4R gene was cloned and sequenced. Meanwhile,the MC4R gene sequence and the amino acid residues were also analyzed.The RFLP of goose MC4R gene were detected using the restriction enzymes TaqI and HinfI, which association with important economic traits in goose was analyzed.The results as follows:1.The goose MC4R gene was cloned and sequenced.The cDNA length of the gene was 996bp,and the sequence had been submitted to the GenBank,accession No:DQ482582.2.Sequence analysis showed that the homology between goose and chicken was 95.3%. The homologies between goose and other animals were 75%to 79%.The phylogenetic tree from different species of MC4R gene showed that the differentiation between birds and mammals started early,and the differentiation among herbivore,pig,primate and sarcophagi was evident specificities.3.The goose MC4R gene coded 331 amino acids.The protein compared with other 12 species showed that the goose was most closely related to chicken,and more closely related to mammals and fishes.4.The codon usage frequency of MC4R gene in goose was calculated,and the codon usage frequency was compared with other 12 species.The results showed that the Ala prefered to GCA;Arg prefered to AGG,CGC and CGG;Gly prefered to GGC and GGG;Leu prefered to CUC and CUG;Pro prefered to CCU;which showed the nonrandomness of codon usage. Comparing the results,conspicuous difference was found in the codon usage of different species,The similarity coefficient of codon usage between goose and chicken was 0.801, between goose and mammal such as human,was 0.630,and 0.50～0.60 between goose and other species.These showed that,different species had different codon usage.5.Hydrophilicity,average charge and surface probability of amino acid residues of MC4R in goose were analyzed.The results showed that the hydrophilicity,averagy charge and surface probability of amino acid residues varied with MC4R seven transmembrane characteristic. 6.By PCR-HinfI-RFLP,two genotypes(AA and AB)were tested in Wanxi White gander×Sichuan White goose,results of association analysis between the RFLP and the traits showed that only AA genotype had significantly effect(P＜0.01)in increasing body weight, Half-eviscerated weight and eviscerated weight,had significantly negative effect(-2.008 and-2.214)in stomachus muscularis ratio and abdomen fat ratio,also had significantly effect(P＜0.05)in increasing liver weight heart weight,AA genotype had significantly effect(P＜0.05)in losting dehydration of chest muscle;but AB genotype had no significantly effect in all economic traits(P＞0.05).