Influence Of Glycolysis On Meat Quality Traits And Identification Of Differentially Expressed Proteins In Bei Jing Black Pigs

In this paper,the effects of metabolic differences on meat quality were studied by investigating the activity of muscle glycolytic enzymes and their products after slaughter,and the molecular mechanism affecting meat quality traits was revealed by proteomics.The longissimus dorsi muscles from Beijing black pigs(210 days)were collected.The 24 h pH,24 h L*,and the 72 h Drip(DL)loss were measured.The activity of PK and LDH,as well as the content of pyruvate and lactic acid were measured at 6 h and 24 h after slaughter.Correlation analysis was carried out on meat quality traits and glycolysis related enzymes and metabolites to reveal the effects of muscle glycolysis on meat quality traits.Identified by TMT proteomic quantification technology.Differential proteins of two groups of samples(group G: high pH,low meat color,and low DL;Group B: low pH,high meat color,and high DL,which had 4 individuals in each group were screened.The regulation roles of differencial proteins related to identified was analyzed.The results are as follows:1.(1)The means of 24 h pH,24 h L* and 72 h DL were 5.937,50.612 and 1.412,respectively.The24 h pH showed extremely significant negative correlation with both the 24 h L* and the 72 h DL(P <0.01).The 24 h L* showed extremely significant positive correlation with 72 h DL(P < 0.01).(2)The activities of PK and LDH in 24 h were lower than those in 6 h(P < 0.01).The 6 h LDH activity was significantly and positively associated with lactate concentration either in 6 or 24 h(P < 0.05).(3)The 6h lactate concentration and LDH activity had extremely significant positive correlation with 72 h DL(P< 0.01),and extremely significant negative correlation with the 24 h pH(P < 0.01).The 24 h L* had extremely significant positive correlation with the 6 h lactate concentration(P < 0.01),and significant positive correlation with the 6 h LDH activities(P < 0.05).2.By using TMT proteomic quantification technology,differential proteins from the longissimus dorsi muscle samples were screened.A total of 3591 proteins were identified,and a total of 140 differential proteins were identified with criterion of p-value < 0.05 and 1.3 fold change.Compared with group B,there were 17 upregulated proteins and 123 down-regulated proteins in group G.3.According to the GO analysis results,the differential proteins were mainly involved in the biological processes of glucose metabolism,Ubiquitin-dependent protein catabolism,glucagon signaling pathway,muscle contraction,insulin signaling pathway,insulin signaling pathway,proteasome,calcium ion transport,cAMP signaling pathway,adhesion.Including down-regulated proteins such as TPM1,PPP1R3 A,RACK1,AHNAK,BSG,BZW2,GSTO1,hnRNPK,KRT18 and up-regulated proteins such as PYGB,CAMK2 A and HRC.In summary,LDH might have more important role in the regulation of muscle glycolysis after slaughter and its activity is closely related to lactate concentration and meat quality.The LDH activity and lactate concentration could be used to evaluate the meat quality.In the study of porcine proteomics,the glucose metabolism,adhesion,muscle contraction pathway and calcium channel are were more important in the regulation of meat quality metabolic pathways affecting muscle metabolism.