| Xinjiang brown cattle(BC)is an excellent local beef breed with dual-purpose of milk and meat characterized by its tolerance to rough feeding,cold weather and good grazing performance.Whereas Angus cattle(AC)is a well-known beef cattle breed worldwide by its early maturity,fast fattening,tender meat with the obvious marbling.The most of beef quality traits,such as back fat thickness,marbling,tenderness,and the intramuscular fat deposition,are closely involved in the process of body fat metabolism.A large number of studies on beef quality traits and related regulatory factors of AC have been well documented,however,systematic comparative study on the fat metabolism related beef quality traits(LMRBQT)and their control mechanism between BC and AC are lacking.Studies have found that the gut microbiota is closely associated with the host’s metabolism,growth and development,and diseases.It is suggested that changes of the gut microbiota composition and their metabolites may be correlated with some LMRBQT in XC and AC.Therefore,in this study,10 BC and 10 AC raised under the same environmental and feeding condition were selected and sloughed at 18-month-old,LMRBQT of the loin muscle aera,the muscular fiber area,the backfat thickness,the intramuscular fat content,and the morphometry of fat cells were measured;the rectal fecal samples were collected for analyzing gut microbiota diversity,metagenomics and metabolomics to reveal the correlation of differential features of gut microbiota structure,function,and metabolic pathways with host’s LMRBQT thereafter the differential controlling mechanism.between BC and AC.Differential proteins in longissimus muscle were analyzed by means of high-throughput proteomic sequencing;Proteomics was used to analyze the differential proteins of longissimus dorsi muscle to elucidate the regulation of intramuscular fat metabolism.Therefore to explore the correlation of the changes of gut microbiota and their metabolites with host’s LMRBQT and the differential controlling mechanism.The experimental results were as the fallowing:1.Differentials in beef quality between BC and AC: Xinjiang brown cattle’s eye muscle area,intramuscular fat content and ash content were significantly lower than Angus cattle(P <0.05);Xinjiang brown cattle backfat thickness was significantly higher than Angus cattle(P <0.01);Xinjiang brown cattle muscle fiber cross-sectional area and total intramuscular fat area were significantly lower than Angus cattle(P <0.05).It is suggested that the beef quality traits related to lipid metabolism of the longissimus dorsi muscle of Angus cattle are better than Xinjiang brown cattle in this experiment.2.Differential gut microbiota and their functions between BC and AC: the relative richness of Proteobacteria in Xinjiang brown cattle is significantly higher than that of Angus cattle(P<0.01);the relative richness of Chlorobi is significantly higher than that of Angus cattle(P <0.05).The relative richness of Roseburia in Xinjiang was extremely significantly higher than that of Angus cattle(P <0.01),and the relative richness of Clostridium was significantly lower than that of Angus cattle(P <0.05);5-7N15 and Prevotella was significantly higher than Angus cattle(P<0.05).The relative richness of Blautia wexlerae and Ruminococcus gnavus in Xinjiang brown cattle was significantly higher than that of Angus cattle(P <0.01);the relative richness of Prevotella copri was significantly higher than that of Angus cattle(P <0.05).In the functional pathway of lipid metabolism,the relative richness of Prevotella intermedia and Escherichia coli in Xinjiang brown cattle was significantly higher than that of Angus cattle(P <0.05).Correlation analysis between lipid metabolism-related beef quality indicators and lipid metabolism-related functional flora found that Escherichia coli is a lipid metabolism-related functional flora,and is correlated with lipid metabolism-related beef quality indicators,which is the key to the difference in fat metabolism-related beef quality between the two varieties.3.Differential gut microbial metabonomics between BC and AC: the different metabolites of the gut microbiota of Xinjiang brown cattle and Angus cattle mainly include: oxoglutaric acid,succinic acid,L-malic acid,fumaric acid,L-aspartic acid,L-Glutamic acid,L-asparagine and γ-aminobutyric acid.Spearman correlation analysis shows that these different metabolites are all related to beef quality traits related to lipid metabolism.Among them,Escherichia coli is positively correlated with γ-aminobutyric acid,L-asparagine and fumaric acid,and negatively correlated with oxoglutaric acid.It is suggested that oxoglutaric acid,γ-aminobutyric acid,Lasparagine and fumaric acid are biomarkers related to lipid metabolism in the gut microbiota of Xinjiang brown cattle.4.Differential proteins in Longissimus muscle: proteomics analysis and functional studies of differential proteins found that there are 66 differentially expressed proteins in Xinjiang Brown Cattle and Angus,of which 51 are up-regulated proteins and 15 are down-regulated proteins;the functions of differentially expressed proteins are mainly enriched In the MAPK pathway,glyoxylic acid and dicarboxylic acid metabolism pathways.Knockdown of MDH1 and ACAA2 genes in 3T3-L1 cells reduces the expression of PPARγ protein and m RNA,and inhibits the adipogenesis induction of 3T3-L1 cells;successfully isolates BSSCs,which had good cell viability,and can successfully induce adipocytes and myoblasts;After MDH1 and ACAA2 gene knockdown,BSSCs reduced the expression of PPARγ and C/EBPa protein and m RNA,and inhibited the adipogenesis induced by BSSCs.The results showed that the meat quality traits related to fat metabolism of Angus cattle were better than those of Xinjiang brown cattle.The difference of intestinal flora related to lipid metabolism between the two species was Escherichia coli.γ-aminobutyric acid,fumaric acid,Lasparagine and glutaric acid were the differential products of intestinal flora related to lipid metabolism.Protein genes MDH1 and ACAA2 have been shown to inhibit adipogenesis in bovine skeletal muscle satellite cells.This study laid a scientific foundation for exploring the causes of meat quality traits related to fat metabolism in Xinjiang brown cattle,which is of great significance for improving meat quality of xinjiang local beef cattle breeds. |
PDF Full Text Request