Physiological Response And Apoptosis Genes Screening And Expressing At Leukocyte Of Cows Under Heat Stress

Threaten dairy industry by heat stress was emphasised by insider of dairy industry.Dairy healthy were affected by heat stress,even death.It focused the research on the relationship between heat stress and cellular apoptosis because that is important for exploring molecular mechanism of cell apoptosis in the future.In this study,dry Jersey cattle were used as experimentals(n=10,360±40 kg,6.0±0.5 year).Four experiments have been examined under different temperature humidity index(THI)including physiological response,transcriptome analysis and sequencing of leukocyte performed by mRNA-seq,screened key apoptosis genes,verification for FAS pathway through Western blotting and q-PCR as well.Results are as follows:1.The temperature and humidity index(THI)is highest in July-August in southern Chongqing at 2019.Meteorological indicators of dry bulb,wet bulb,humidity and THI were significantly different effected by time of 6:00,10:00 and 14:00(P<0.01).Simultaneously,physiological responses of respiration rate(RR),sweating rate(SR),rectal temperature(RT),skin temperature with hair(ST(hair))and skin temperature without hair(ST(no hair))were significantly different(P<0.01).2.The number of differential expression genes(DEGs)is 1649 at leukocyte of dry Jersey cattle under different THI(THI=77,THI=82 and THI=88).Results showed1303 DEGs were detected in leukocytes at THI=82 within 1093 genes were up-regulated but 201 genes were down-regulated while 857 DEGs at THI=88,within 579 up-regulated but 254 down-regulated,compared to THI=77.Among the genes obtained by transcriptome sequencing,there are 596 genes related to apoptosis,within 29 apoptosis genes with differential expression.There were 24 up-regulating genes including(FAS?CASP3?PARP3)but 5 down-regulating genes including FASLG gene.It showed 127 genes related to heat shock protein(HSP),which was 5 DEGs,within 4 up-regulated(HSP70,CARD15?ENSBTAG00000007746 and DNAJB13)but 1 down-regulated HSPB8.3.GO enrichment analysis on 29 apoptosis DEGs,and 792 GO terms were screened.GO enrichment is mainly in regulation of apoptotic process,regulation of programmed cell death,extrinsic apoptotic signaling pathway,and the death domain receptor,extrinsic apoptotic signaling pathway via death domain receptors,positive regulation of cell death and regulation of cell death.4.KEGG analyzes the functional annotation and enrichment of 29 apoptosis DEGs.KEGG functional annotation mainly focus on three major functions: cell growth and death,immune system and signal transduction.KEGG-enriched signaling pathways mainly include apoptosis signaling pathway,Fox O signaling pathway,TNF signaling pathway,p53 signaling pathway,T cell receptor signaling pathway,natural killer cell-mediated cytotoxicity and IL-17 signaling pathway.5.Western blotting and q-PCR confirmed the selected apoptotic DEGs and HSP70.HSP70,CASP3 and PARP3 increase significantly with increasing THI(P<0.01).However,FASLG decreased significantly with increasing THI(P<0.01).Furthermore,FAS increased from THI = 77 to THI = 82,and then gradually decreased with the increase of THI.Therefore,heat stress can change the expression levels of HSP70,FAS,FASLG,CASP and PARP3.Conclusions:(1)Physiological indicators of RR,SR,RT,ST(hair)and ST(no hair)increase with the increase of THI.(2)It was 1093 up-regulated but 201 down-regulated at THI=82 while 579 up-regulated but 254 down-regulated at THI=88,compared to THI=77.(3)29 apoptosis DEGs were screened from leukocyte of Jersey cattle under heat stress including 24 up-regulated genes but5 down-regulated genes.Meanwhile,5 DEGs to HSP were screened,within 4 up-regulated genes but 1 down-regulated.(4)29 apoptotic DEGs were enriched with GO and KEGG,of which GO enrichment regulation of apoptotic process,regulation of programmed cell death,extrinsic apoptotic signaling pathway,extrinsic apoptotic signaling pathway via death domain receptors,positive regulation of cell death and regulation of cell death;and KEGG function is enriched in apoptosis signaling pathway.(5)Heat stress affects the expression of HSP70,FAS,FASLG,CASP3 and PARP3.