Genetic Effects And Expression Of Genes Related To Carcass And Meat Quality Traits In Domestic Pigeons(Columba Livia)

This research was conducted to detect SNPs in DGAT2,ADSL,FABP1,FABP2 and FABP3 genes in Taishen King Pigeons(Columba livia),and analyse the associations between the SNPs and carcass and meat quality traits.In addition,real-time PCR was performed to study the gene expression characteristics of the five genes at different weeks of age,and histological section method was also performed to reveal the law of muscle fiber development.Furthermore,lentivirus mediated RNA interference was applied to evaluate the influence of proliferation and apoptosis in pigeon embryo fibroblast cells after knocking down FABP1,FABP2 and FABP3 gene.The main results are listed as follows:1.Direct DNA sequencing was used to detect polymorphisms in DGAT2,ADSL,FABP1,FABP2 and FABP3 genes,and associations between the SNPs and carcass and meat quality traits were also analyzed.The analysis results are as follows:(1)Five SNPs were found in DGAT2 gene,and two of them had significantly associations with carcass and meat quality traits.In the G18398T,the abdominal fat weight and abdominal fat rate in AA and AB genotypes were higher than these in BB genotype(P<0.01),while BB genotype had higher IMP and IMF content than AA and BB genotype.In the SNP of G22484C,the genotype AA showed highest carcass trait values(P<0.01),while the genotype BB represented better meat quality,compared with AA and AB genotypes.(2)Nine SNPs were found in ADSL gene,and two of them had significantly associations with carcass and meat quality traits.In the SNP of C13065G which was located in exonll,the IMP content of breast muscle in AA and AB genotype was higher than BB genotype(P<0.01).And another SNP G10696A located in exon10 was significantly associated with carcass rate,in which AA and AB genotype were higher than BB genotype(P<0.01).(3)Five SNPs were found in FABP1 gene,and three of them had significantly associations with carcass and meat quality traits.Association analysis revealed that in the SNP of T1298C,the genotype AA and BB showed higher(P<0.05)live weight,semi-eviscerated weight and eviscerated weight than AB genotype.In the SNP of G161C,the genotype BB had higher(P<0.05)concentrations of inosinic acid in breast muscle than AA genotype.In the SNP of C1376T,individuals with BB genotype showed higher(P<0.05)L*and b*value than AB genotype,and BB genotype had higher(P<0.05)centrations of inosinic acid than AA genotype,while genotype AB showed higher(P<0.05)intramuscular fat than genotype AA genotype.(4)Nine SNPs were found in FABP3 gene,and three of them had significantly associations with carcass and meat quality traits.In the SNP of C3128T located in exon2,AA genotype had the highest(P<0.05)live weight,carcass weight and eviscerated weight.In the SNP of G3305A located in exon3,individuals with genotype AB had significantly higher(P<0.05)intramuscular fat.In the SNP of A3313G located in exon3,the genotype AA showed higher(P<0.01)inosinic acid and intramuscular fat,compared with BB genotype.(5)No SNPs was found in FABP2 gene.DGAT2,ADSL,FABP1 and FABP3 gene polymorphisms are significantly associated with carcass and meat quality traits in domestic pigeons,and could be used as genetic markers in the breeding of pigeons.2.Real-time PCR was performed to research the gene expression characteristics of the five genes at different weeks of age.The results showed that 5 genes expressed widely in different tissues of pigeons at different weeks of age.DGAT2 gene had relatively higher expression level in spleen,glandular stomach,lung,liver and fat tissues,while heart and breast muscle had lower expression level.Meanwhile,the expression levels of most tissues in 3 and 4 weeks were higher than those of 1,2 and 3 weeks.ADSL gene had relatively higher expression level in muscular stomach,lung,spleen and kidney,while liver showed lower expression level.FABP1 gene expressed highest in liver,and fat and small intestine also had relatively high expression level,while heart and glandular stomach had low expression level.FABP2 gene had relatively higher expression level in liver,small intestine,fat and spleen,while in glandular stomach and breast muscle it was relatively lower.In all weeks of age,liver and spleen had significantly higher FABP3 gene expression level than other tissues,while heart,breast muscle and glandular stomach showed lower expression level.3.Histological section method was firstly applied to reveal the law of pigeon muscle fiber development,including fiber diameter,cross-sectional area,density,and thickness of endomysium and perimysium.Results showed that muscle fiber of pigeon developed relatively fast from Ow to 4w.The fiber diameter,cross-sectional area,endomysium and perimysium thickness increased linearly with the increasing age,while fiber density decreased with the increasing ages.Muscle fiber density showed a very significant negative correlation with fiber diameter,cross-sectional area and endomysium and perimysium thickness.4.Pigeon embryo fibroblast cell line was built to research the influence of proliferation and apoptosis after knocking down FABP1,FABP2 and FABP3 gene by lentivirus mediated RNA interference.Result showed that he proliferation rate of fibroblasts decreased at some degree after knocking down FABP1,FABP2 and FABP3 gene.After knocking down FABP1gene,the FAS and Caspase-3 gene up-regulated 3.1 and 2.2 times respectively;after knocking down FABP2 gene,the FAS and Caspase-3 gene up-regulated 1.95 and 1.82 times respectively;after knocking down FABP3 gene,the FAS and Caspase-3 gene up-regulated 5.64 and 4.98 times respectively,indicating that apoptosis significantly increased after knocking down FABP1,FABP2 and FABP3 gene.In conclusion,DGAT2,ADSL,FABP1 and FABP3 gene polymorphisms are significantly associated with carcass and meat quality traits in domestic pigeons,and could be used as genetic markers for marker-assisted breeding of pigeons.The real-time PCR results indicated that 5 genes widely expressed in different tissues at different weeks of age.What's more,The fiber diameter,cross-sectional area,endomysium and perimysium thickness increased linearly with the increasing age,and muscle fiber density showed a very significant negative correlation with fiber diameter,cross-sectional area and endomysium and perimysium thickness.In addition,RNAi results showed that the proliferation rate of fibroblasts decreased and apoptosis increased significantly after interfering FABP1,FABP2 and FABP3 gene,indicating that these 3 genes had an important function in cells.