| Bactrian camel has a strong ability to adapt to the environment and is an important animal species in desert areas of China.In recent years,with the increasing demand for camel products in China’s consumer market,the number of camels is increasing year by year.About 93% of the surface of Alashan League in Inner Mongolia is desert,Gobi and desert steppe.Alashan Bactrian camels account for about 65% of local large livestock and 30% of the total number of camels in the country.Camels are mostly natural grazing,which can provide natural and high quality protein resources for the market.At the same time,it can also greatly promote local economic development and the enthusiasm of herdsmen to get rich.However,the natural environment in desert area is complex and changeable,nutritional restriction and compensatory growth are practical problems in camel production,and fat deposition and muscle growth directly determine the value of meat products,which is an important economic character in the process of camel meat production.Therefore,it is helpful for people to understand and master the regulation law of camel meat growth by exploring the molecular mechanism of the effect of nutritional restriction and compensation on camel meat fat deposition and muscle growth,and screening out the key influencing factors.It will provide a reference basis for the development of camel meat industry in China in the future.Based on RNA-seq transcriptome sequencing and LC-MS non-targeted metabolic group technology,six Alxa Bactrian camels were selected to undergo normal diet(a),fasting(b)and recovery diet(c),fore hump(F),hind hump(H),subcutaneous fat(S)and biceps femoris(M),were collected for transcriptome and metabolic group sequencing and bioinformatics analysis.The molecular regulation model of each tissue in the process of nutritional restriction and compensation was revealed,and the candidate genes and marker metabolites related to fat deposition and muscle growth were screened and verified by Realtime PCR and phenotypic experiments,which provided a basis for finally revealing the molecular mechanism of fat deposition and muscle growth in camel meat.The specific results of this study are as follows:1.The differential genes and metabolites of(ab)from normal period to fasting period and from fasting period to recovery period were collected and intersected respectively,and the genes and metabolites with significant changes before and after fasting were screened.The differential genes of anterior hump,rear hump,subcutaneous fat and muscle tissue were375,464,64 and 417 respectively,and the differential metabolites were 112,117,93 and114 respectively.These differential genes and differential metabolites are involved in the whole process of nutritional restriction and compensation.2.According to the enrichment results and functional annotation of genes,15(ELOVL5、SCD、HSD17B12、ELOVL6、ELOVL2、FOXO3、CREB3L3、LEP、ACACA、LPL、PPARA、PPARG、EHHADH、PLB1、FASN),17(FADS2、SCD、CPT1B、LPL、PPARA、PPARG、EHHADH、ELOVL5、HSD17B12、FASN、CREB3L3、LEP、AGPAT2、ACADSB、ELOVL6、ACACA、ADCY5),6(FASN、ACACA、LEP、SCD、ELOVL6、LPL)and 7(CPT1A、EHHADH、GALC、NEU3、HACD1、PNPLA2、LOC102522750)genes related to fat deposition were screened out in fore hump,hind hump,subcutaneous fat and muscle tissue,respectively,which are mainly involved in fatty acid oxidation,lipid metabolism and fatty acid synthesis.In addition,a total of 16 genes(GDNF、MYL1、TMOD4、CHRNA1、HOMER1、PGAM2、LOC102510524、LOC106728840、LOC102505376、LOC102508086、TRIB1、HMOX1、FBXO32、MSTN、ACTN3、MYOD1)related to muscle growth were screened,which are involved in biological processes such as muscle cell growth and atrophy and actin cytoskeleton conduction.The up-and-down changes of candidate genes in various tissues suggested that in the fasting stage,the process of fat deposition in anterior hump,posterior hump,subcutaneous fat and muscle tissue was blocked,while the fatty acid oxidation process was enhanced,while the growth of muscle tissue was inhibited.3.Based on the enrichment analysis of differential metabolites,12(cholic acid,glycerophosphate,choline,cis-octadecenoic acid,glycine,glycine-chenodeoxycholic acid,pregnenolone,22 enoic acid,22 carbon hexaenoic acid,palmitic acid,glycyrrhizic acid,cortisol),15(cholic acid,6-keto-prostaglandin E1,cis-octadecenoic acid,glycinechenodeoxycholic acid,taurine,pregnenolone,deoxycortisone,19-hydroxyandrost-4-en-3-line 17-Dione,ethanolamine phosphate,linoleic acid,γ-linolenic acid,22 carbon hexaenoic acid,adrenalone,glycine,phosphocholine)and 12(cholic acid,5-androstane-17’-ol-3-one,6-keto prostaglandin E1,glycine,cis-octadecenoic acid,glycine-chenodeoxycholic acid,deoxycortisone,pregnenolone,linoleic acid,γ-linolenic acid,L-serine,22 carbon hexaenoic acid)fat deposition marker metabolites were screened from fore hump,hind hump and subcutaneous fat respectively,and 12 fat deposition marker metabolites(rape oil sterol,cholic acid,glycine,5’-androstane-17’-ol-3-one,palmitic acid,cis-octadecenoic acid,glycine-chenodeoxycholic acid,phosphocholine,L-serine,adrenaline,deoxycortisone,choline)and 6 muscle growth marker metabolites(rape oil sterol,cholic acid,glycine,5’-androstane-17’-ol-3-one,palmitic acid,cis-octadecenoic acid,glycine-chenodeoxycholic acid,phosphocholine,L-serine,adrenaline,deoxycortisone,choline)were selected from muscle tissue.These metabolites are involved in lipid metabolism,amino acid metabolism,carbohydrate metabolism,biosynthesis of other secondary metabolites and energy metabolism.The up-and-down changes of marker metabolites in each tissue showed that the decomposition process of hump before fasting,posterior hump and subcutaneous fat decomposition accelerated and some anti-inflammatory factors increased,muscle fatty acid oxidation accelerated,and cell growth was blocked.4.In order to explore the changes of fat deposition and muscle growth in each tissue after compensatory growth,we analyzed the function and enrichment of differential genes and metabolites between stages an and c in each tissue.The results showed that before and after compensatory growth,7(ELOVL6、ELOVL5、ELOVL3、FABP3、FADS2、SCD、LPL),5(ELOVL3、ELOVL6、ACOT7、PDE3B、LIPE),3(FASN、ACACA、SCD)and 9(ACSL6、FABP3、PLIN2、SCD、ELOVL6、ITGA4、LPAR2、IQGAP3、MYLK4)candidate genes in front hump,rear hump,subcutaneous fat and muscle tissue were related to fat deposition and muscle growth,respectively.the up-and-down changes of these candidate genes are beneficial to fat deposition and muscle growth in phase C.In addition,8(palmitic acid,choline,cholic acid,glycine,glycine-chenodeoxycholic acid,adrenalone,pregnenolone,phosphocholine),8(adrenaline,cis-octadecenoic acid,cholic acid,glycine,glycine-chenodeoxycholic acid,pregnenolone,deoxycortisone,glycerophosphate),8(cisoctadecenoic acid,cholic acid,glycine,glycine-chenodeoxycholic acid,arachidonic acid,6-keto-prostaglandin E1,linoleic acid,5-androstane-17’-ol-3-one)and 7(cholic acid,glycine,phosphocholine,L-aspartic acid,3-ethyl 5-cyclic adenosine monophosphate,rapeseed sterol,corticosterone)marker metabolites related to fat deposition and muscle growth were screened from front hump,rear hump,subcutaneous fat and muscle tissue,respectively.the up-and-down changes of these marker metabolites are beneficial to fat deposition and muscle growth in phase C.It is suggested that compensatory growth may be beneficial to fat deposition and muscle cell growth in Bactrian camels.5.The relative quantitative and phenotypic test data of Real-time PCR showed that during fasting period,camel lipolysis increased and mediated reversible insulin response,insulin resistance in front hump and rear hump,and increased insulin sensitivity in muscle tissue.It is speculated that this phenomenon may help camels better resist hunger.In this study,transcriptome and metabolome methods were used,combined with Realtime PCR technology and phenotypic test,not only candidate genes and marker metabolites related to camel fat deposition and muscle growth were screened,but also the phenomenon of reversible insulin resistance during fasting period was further revealed,which will provide a reference for revealing the molecular mechanism of camel meat fat deposition and muscle growth. |
