| Chicken,as the second largest meat product in China,is favored by consumers for its high protein and low fat.Animal fat can be divided into abdominal fat(AF),subcutaneous fat and intramuscular fat(IMF)according to different deposition sites,which will affect the economic value of livestock and poultry products.IMF content is closely related to meat quality and properties such as tenderness and flavor,abdominal fat is the waste of broiler slaughtering and processing,the excessive deposition of which will reduce feed remuneration and affect production benefits.As there is the positive correlation between IMF and AF,which makes it difficult to improve the two traits simultaneously.At present,the molecular mechanism of differential deposition of IMF and AF in chickens has not been systematically elucidated yet.The key genes and signaling pathways affecting the differential deposition of breast muscle and abdominal fat tissue of Wenchang Chicken were mined by high-throughput sequencing technology on the basis of the variation of lipid metabolism between breast muscle and abdominal fat tissue of Wenchang Chicken,which is capable of providing the theoretical basis for genetic improvement of high-quality chicken with high IMF and low AF,and also providing ideas for the integration of nutrition regulation technology with promoting high-quality chicken production in the further.In Experiment 1,the relative fat content,lipid composition,fatty acid composition and metabolites in breast muscle and abdominal fat tissue of 98-day-old Wenchang hens(n = 50)were determined and compared.The results showed that triglyceride(TG)was the main lipid component in the two tissues,but TG content in breast muscle was significantly lower than that in abdominal fat(P < 0.01),while PLIP content was significantly higher than that in abdominal fat(P < 0.01).The results of the experiments in vitro showed that the TG content of preadipocytes in the abdominal fat was significantly higher than that of intramuscular adipocytes(P < 0.05),but there was no difference in PLIP content,which suggested that the difference of fat deposition between breast muscle and abdominal fat tissue is mainly due to TG and the difference of PLIP mainly comes from muscle cells.The results of fatty acid(FA)composition showed that C16:0,C16:1,C18:1n9c,C18:2n6c may be the main fatty acids leading to the difference of TG.The results of metabonomics showed that the metabolites in breast muscle and abdominal fat were significantly enriched in carbon metabolism pathway(P < 0.05),including citric acid,acetyl phosphate and other differential metabolites,which were significantly higher than those in the abdominal fat tissue,suggesting that IMF deposition was mainly from de novo synthesis,while the deposition of abdominal fat was mainly from exogenous intake.In Experiment 2,transcriptome sequencing technology was adopted to analyze the expression profiles of breast muscle and abdominal fat tissues of random individuals,moreover,the weighted coexpression network analysis(WGCNA)(n = 18)and differential gene analysis(n = 3)were performed subsequently.Combined analysis of WGCNA and differential genes showed that the breast muscle tissue mainly synthesized IMF through GAPDH,LDHA,GPX1,GBE1 and other genes,while abdominal fat tissue mainly caused abdominal fat deposition through FABP1,ELOVL6,SCD and ADIPOQ and other genes involved in the metabolism of acetyl-coenzyme A and glycerophospholipids.Among them,glycolysis / glucose production,starch and sucrose metabolism play an important role in IMF deposition,while PPAR signaling pathway,glycerophospholipid metabolism and other fat metabolism related signaling pathways regulate abdominal fat deposition.In conclusion,this study identified the key regulatory genes of IMF deposition and abdominal fat deposition.The molecular mechanism of IMF and AF differential deposition was elucidated by key differential metabolites and signal pathway,which provided theoretical support for the production of highquality broilers. |
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