| Animal lipid metabolism is mainly affected by factors such as heredity,rearing,and external environment.There are differences in fat metabolism and genetic mechanisms among different species.The intramuscular fat content of cattle is closely related to meat quality and taste,affecting the tenderness of meat quality,flavor,marble pattern and key factors of nutritional value.The proper amount of intramuscular fat deposition can increase the marble pattern grade,reduce the shearing force of beef,and increase beef The palatability.However,fat deposition and fatty acid metabolism are complex and highly coordinated gene expression programs.Therefore,lipid metabolism has been a hot and difficult topic in animal and poultry research.Based on previous transcriptomic analysis,this study screened the carnitine palmitoyltransferase 1B(CPT1B),a candidate gene related to lipid metabolism in cattle.CPT1 B is a member of the CPTs family.The protein encoded by this gene is located in the outer mitochondrial membrane and is the key rate-limiting enzyme for fatty acid beta-oxidation.It plays an important role in the regulation of fatty acid depletion and can be regulated by interaction with other genes in the lipid metabolism signaling pathway.Intracellular lipid metabolism.It has a higher expression level in heart and skeletal muscle tissue.Carnitine,also known as vitamin Bt,is a type of vitamin that is a high-level compound in animal tissues that is involved in fat metabolism.Carnitine mediates long-chain fatty acids in the cytosol and enters the mitochondria for ?-oxidation.The acyl-CoA formed in the cytoplasm cannot pass through the inner mitochondrial membrane and must rely on the three carnitine enzymes on the inner membrane(meat Toxalkin acyltransferase 1,carnitine-acylcarnitine translocase and carnitine acyltransferase 2)can enter the mitochondrial matrix.This delivery system is called the carnitine shuttle system.The content of carnitine in chicken and fish is very low,while the content of carnitine in beef is very high.This experiment is to study the carnitine acyltransferase 1b necessary for the transport of carnitine into mitochondria,and then analyze the effect of CPT1 B gene on the quality and fat metabolism related traits of Chinese Simmental beef,in order to improve the quality of beef traits and select Education provides molecular genetic markers.In this experiment,the Chinese Simmental cattle population was selected as the study object.First,the genetic polymorphism of CPT1 B gene in Chinese Simmental cattle population was screened,and the gene frequency of CPT1 B gene-related mutation sites in Chinese Simmental cattle population was analyzed.And genotype frequency and correlation with bovine carcass traits,meat quality and fat deposition traits.Secondly,the overexpression vector and knockout vector of CPT1 B gene were constructed to analyze the effect of up-regulation and silencing of CPT1 B gene on the changes of triglyceride levels in bovine fetal fibroblasts.The results showed that:(1)CPT1B gene has 4 SNPs in Chinese Simmental herds,which are I533T>C,I997G>C,E1241C>A,I7763T>C.The I533T>C locus was significantly correlated with the carcass length of Chinese Simmental cattle(P<0.05);The I997G>C locus was significantly associated with the backfat thickness of Chinese Simmental cattle(P<0.05).There was a significant correlation between the E1241C>A locus and Chinese Simmental cattle slaughter rate and eye muscle area(P<0.05);The I7763T>C locus was significantly correlated with body length,waist thickness,and eye muscle area in Chinese Simmental cattle(P<0.05),and was significantly associated with liver weight and spleen weight(P<0.01).(2)12 haplotype combinations were formed at the 4 SNPs of the CPT1 B gene in the Simmental herds: CCAC,CCAT,CCCC,CCCT,CGAC,CGAT,CGCC,CGCT,TCAC,TCAT,TCCC,TCCT,where TCCT,CCAC,and CGAC are dominant haplotypes.There was a significant correlation between TCCT and China's Simmental hepatic weight,kidney fat weight,slaughter pH,back fat thickness and fat coverage(P<0.05);CCAC and China's Simmental cow's liver Weight,weight of kidney,slaughter,PH,back fat thickness and fat coverage were significantly correlated(P<0.05);There was significant correlation between liver weight,slaughter pH,back fat thickness and fat coverage of CGAC and Chinese Simmental cattle(P<0.05).(3)Analysis of the fatty acid composition of the four SNPs of CPT1 B gene and Chinese Simmental cattle showed that the CPT1 B gene has the I533 T>C,I997 G>C and E1241 C>A and Chinese Ximen Tower.There was no significant correlation between the fatty acid composition of er cattle and only the I7763 T>C site was significantly associated with arachidonic acid in Chinese Simmental cattle(P<0.05).(4)With the increase of CPT1 B gene expression in bovine fetal fibroblasts,the content of triglyceride increased significantly(P<0.05).In the CPT1 B knockout bovine fetal fibroblasts,as the expression level of CPT1 B decreased,the triglyceride content showed a decreasing trend but did not reach a significant level(P>0.05).CPT1B gene regulates the synthesis of triglyceride and deposition of fat during the fat metabolism of cattle,but the function and mechanism of CPT1 B gene need further study. |
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