Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify pro...Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves.Antimicrobial susceptibility tests were performed using the disk diffusion method,and PCR was used to detect resistance and virulence genes.The prevalence of multidrug resistant(MDR)E.coli was 77.8%in dairy cattle and 63.6%in beef cattle.There were high resistance rates to penicillin(100%,100%)and ampicillin(96.3%,86.4%)in E.coli from dairy cattle and beef cattle.Interestingly,resistance rate to antimicrobials and distribution of resistance genes in£coli isolated from dairy cattle were higher than those in beef cattle.Further analysis showed that the most prevalent resistance genes were blojm and oodAl in dairy cattle and beef cattle,respectively.Moreover,seven diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,F41,K99 and STa)were present in the isolates from dairy cattle,with a prevalence ranging from 3.7%to 22.22%.Six diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,hylA and F41)were identified in the isolates from beef cattle,with a prevalence ranging from 2.27%to 63.64%.Our results provide important evidence for better exploring their interaction mechanism.Further studies are also needed to understand the origin and transmission route of£coli in cattle to reduce its prevalence.展开更多
Background:Bovine mammary epithelial cells after calving undergo serious metabolic challenges and oxidative stress both of which could compromise autophagy.Transcription factor EB(TFEB)-mediated autophagy is an import...Background:Bovine mammary epithelial cells after calving undergo serious metabolic challenges and oxidative stress both of which could compromise autophagy.Transcription factor EB(TFEB)-mediated autophagy is an important cytoprotective mechanism against oxidative stress.However,effects of TFEB-mediated autophagy on the oxidative stress of bovine mammary epithelial cells remain unknown.Therefore,the main aim of the study was to investigate the role of TFEB-mediated autophagy in bovine mammary epithelial cells experiencing oxidative stress.Results:H_(2)O_(2) challenge of the bovine mammary epithelial cell MAC-T increased protein abundance of LC3-II,increased number of autophagosomes and autolysosomes while decreased protein abundance of p62.Inhibition of autophagy via bafilomycin A1 aggravated H_(2)O_(2)-induced reactive oxygen species(ROS)accumulation and apoptosis in MAC-T cells.Furthermore,H_(2)O_(2) treatment triggered the translocation of TFEB into the nucleus.Knockdown of TFEB by siRNA reversed the effect of H_(2)O_(2) on protein abundance of LC3-II and p62 as well as the number of autophagosomes and autolysosomes.Overexpression of TFEB activated autophagy and attenuated H_(2)O_(2)-induced ROS accumulation.Furthermore,TFEB overexpression attenuated H_(2)O_(2)-induced apoptosis by downregulating the caspase apoptotic pathway.Conclusions:Our results indicate that activation of TFEB mediated autophagy alleviates H_(2)O_(2)-induced oxidative damage by reducing ROS accumulation and inhibiting caspase-dependent apoptosis.展开更多
Background:In early lactation,bovine mammary epithelial cells undergo serious metabolic challenges and oxidative stress both of which could be alleviated by activation of autophagy.Nuclear factor erythroid 2 related f...Background:In early lactation,bovine mammary epithelial cells undergo serious metabolic challenges and oxidative stress both of which could be alleviated by activation of autophagy.Nuclear factor erythroid 2 related factor 2(NFE2L2),a master regulator of cellular redox homeostasis,plays an important role in the regulation of autophagy and oxidative stress.Thus,the objective of this study was to investigate the role of NFE2L2-mediated autophagy on oxidative stress of bovine mammary epithelial cells in response to exogenous free fatty acids(FFA).Results:Exogenous FFA induced linear and quadratic decreases in activities of glutathione peroxidase(GSH-Px),catalase(CAT),and superoxide dismutase(SOD),and increases in the contents of reactive oxygen species(ROS)and malondialdehyde(MDA).Protein abundance of LC3-phosphatidylethanolamine conjugate(LC3-Ⅱ)and the number of autophagosomes and autolysosomes decreased in a dose-dependent manner,while protein abundance of p62 increased in cells challenged with FFA.Activation of autophagy via pre-treatment with Rap attenuated the FFAinduced ROS accumulation.Importantly,FFA inhibited protein abundance of NFE2L2 and the translocation of NFE2L2 into the nucleus.Knockdown of NFE2L2 by siRNA decreased protein abundance of LC3-Ⅱ,while it increased protein abundance of p62.Furthermore,sulforaphane(SFN)pre-treatment attenuated the FFA-induced oxidative stress by activating NFE2L2-mediated autophagy.Conclusions:The data suggested that NFE2L2-mediated autophagy is an important antioxidant mechanism in bovine mammary epithelial cells experiencing increased FFA loads.展开更多
基金This study was supported by the National Science and Technology Ministry(2014BAD13B03-1)the project supported by the Heilongjiang Province Farms General Administration of China(HNK135-04-03)This work was supported by a grant from the Heilongjiang Bayi Agricultural University Support Program for San Heng San Zong(TDJH202002).
文摘Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves.Antimicrobial susceptibility tests were performed using the disk diffusion method,and PCR was used to detect resistance and virulence genes.The prevalence of multidrug resistant(MDR)E.coli was 77.8%in dairy cattle and 63.6%in beef cattle.There were high resistance rates to penicillin(100%,100%)and ampicillin(96.3%,86.4%)in E.coli from dairy cattle and beef cattle.Interestingly,resistance rate to antimicrobials and distribution of resistance genes in£coli isolated from dairy cattle were higher than those in beef cattle.Further analysis showed that the most prevalent resistance genes were blojm and oodAl in dairy cattle and beef cattle,respectively.Moreover,seven diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,F41,K99 and STa)were present in the isolates from dairy cattle,with a prevalence ranging from 3.7%to 22.22%.Six diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,hylA and F41)were identified in the isolates from beef cattle,with a prevalence ranging from 2.27%to 63.64%.Our results provide important evidence for better exploring their interaction mechanism.Further studies are also needed to understand the origin and transmission route of£coli in cattle to reduce its prevalence.
基金This work was supported by the National Natural Science Foundation of China(Beijing,China,grant no.32002348 and 32072931)the Project funded by China Postdoctoral Science Foundation(Beijing,China+3 种基金grant no.2019 M661316)the Heilongjiang Postdoctoral Science Foundation(Heilongjiang,ChinaGrant No.LBH-Z19090)the Personnel Foundation in Heilongjiang Bayi Agricultural University(XYB201909).
文摘Background:Bovine mammary epithelial cells after calving undergo serious metabolic challenges and oxidative stress both of which could compromise autophagy.Transcription factor EB(TFEB)-mediated autophagy is an important cytoprotective mechanism against oxidative stress.However,effects of TFEB-mediated autophagy on the oxidative stress of bovine mammary epithelial cells remain unknown.Therefore,the main aim of the study was to investigate the role of TFEB-mediated autophagy in bovine mammary epithelial cells experiencing oxidative stress.Results:H_(2)O_(2) challenge of the bovine mammary epithelial cell MAC-T increased protein abundance of LC3-II,increased number of autophagosomes and autolysosomes while decreased protein abundance of p62.Inhibition of autophagy via bafilomycin A1 aggravated H_(2)O_(2)-induced reactive oxygen species(ROS)accumulation and apoptosis in MAC-T cells.Furthermore,H_(2)O_(2) treatment triggered the translocation of TFEB into the nucleus.Knockdown of TFEB by siRNA reversed the effect of H_(2)O_(2) on protein abundance of LC3-II and p62 as well as the number of autophagosomes and autolysosomes.Overexpression of TFEB activated autophagy and attenuated H_(2)O_(2)-induced ROS accumulation.Furthermore,TFEB overexpression attenuated H_(2)O_(2)-induced apoptosis by downregulating the caspase apoptotic pathway.Conclusions:Our results indicate that activation of TFEB mediated autophagy alleviates H_(2)O_(2)-induced oxidative damage by reducing ROS accumulation and inhibiting caspase-dependent apoptosis.
基金supported by the National Natural Science Foundation of China(Beijing,China,grant no.32072931 and 32002348)Natural Science Foundation of Heilongjiang Province(grant no.LH2020C085).
文摘Background:In early lactation,bovine mammary epithelial cells undergo serious metabolic challenges and oxidative stress both of which could be alleviated by activation of autophagy.Nuclear factor erythroid 2 related factor 2(NFE2L2),a master regulator of cellular redox homeostasis,plays an important role in the regulation of autophagy and oxidative stress.Thus,the objective of this study was to investigate the role of NFE2L2-mediated autophagy on oxidative stress of bovine mammary epithelial cells in response to exogenous free fatty acids(FFA).Results:Exogenous FFA induced linear and quadratic decreases in activities of glutathione peroxidase(GSH-Px),catalase(CAT),and superoxide dismutase(SOD),and increases in the contents of reactive oxygen species(ROS)and malondialdehyde(MDA).Protein abundance of LC3-phosphatidylethanolamine conjugate(LC3-Ⅱ)and the number of autophagosomes and autolysosomes decreased in a dose-dependent manner,while protein abundance of p62 increased in cells challenged with FFA.Activation of autophagy via pre-treatment with Rap attenuated the FFAinduced ROS accumulation.Importantly,FFA inhibited protein abundance of NFE2L2 and the translocation of NFE2L2 into the nucleus.Knockdown of NFE2L2 by siRNA decreased protein abundance of LC3-Ⅱ,while it increased protein abundance of p62.Furthermore,sulforaphane(SFN)pre-treatment attenuated the FFA-induced oxidative stress by activating NFE2L2-mediated autophagy.Conclusions:The data suggested that NFE2L2-mediated autophagy is an important antioxidant mechanism in bovine mammary epithelial cells experiencing increased FFA loads.