[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determinati...[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determination of growth curve and correlation curve between OD 600 values and viable counts,drug susceptibility tests,pathogenicity analysis,and histopathological observations were carried out.[Results]The Streptococcus strain isolated from infected pigs was identified as Streptococcus suis type 2,which was named TA01 strain.TA01 strain reached the growth peak at 6-8 h post-incubation,and viable counts gradually declined after 8 h of incubation.The correlation equation between OD 600 values and viable counts is y=24.659 x-1.076 1,R^2=0.996 7.TA01 strain was sensitive to penicillin,erythromycin,florfenicol and oxacillin,and resistant to ciprofloxacin,polymyxin B and clindamycin.According to the results of pathogenicity analysis,all the mice in 3.6×10^9 cfu/mouse group died within 48,and these dead mice exhibited acute pyaemia septica.Based on the Reed-Muench formula,it was calculated that LD 50 of TA01 strain was 1.137×10^8 cfu/mouse.Pathological examination showed obvious blue-stained bacteria clusters,accompanied by neutrophil infiltration.[Conclusions]TA01 strain was a virulent strain of Streptococcus suis type 2.Compared with Streptococcus strains which were isolated and reported in China,TA01 strain exhibited strong virulence and rapid proliferation.展开更多
Organophosphate esters(OPEs)are widespread in various environmental media,and can disrupt thyroid endocrine signaling pathways.Mechanisms by which OPEs disrupt thyroid hormone(TH)signal transduction are not fully unde...Organophosphate esters(OPEs)are widespread in various environmental media,and can disrupt thyroid endocrine signaling pathways.Mechanisms by which OPEs disrupt thyroid hormone(TH)signal transduction are not fully understood.Here,we present in vivo-in vitro-in silico evidence establishing OPEs as environmental THs competitively entering the brain to inhibit growth of zebrafish via multiple signaling pathways.OPEs can bind to transthyretin(TTR)and thyroxine-binding globulin,thereby affecting the transport of TH in the blood,and to the brain by TTR through the blood-brain barrier.When GH3 cells were exposed to OPEs,cell proliferation was significantly inhibited given that OPEs are competitive inhibitors of TH.Cresyl diphenyl phosphate was shown to be an effective antagonist of TH.Chronic exposure to OPEs significantly inhibited the growth of zebrafish by interfering with thyroperoxidase and thyroglobulin to inhibit TH synthesis.Based on comparisons of modulations of gene expression with the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases,signaling pathways related to thyroid endocrine functions,such as receptor-ligand binding and regulation of hormone levels,were identified as being affected by exposure to OPEs.Effects were also associated with the biosynthesis and metabolism of lipids,and neuroactive ligand-receptor interactions.These findings provide a comprehensive understanding of the mechanisms by which OPEs disrupt thyroid pathways in zebrafish.展开更多
基金Supported by National Key Basic Research Program of China(973 Program)(2017YFD0500605)
文摘[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determination of growth curve and correlation curve between OD 600 values and viable counts,drug susceptibility tests,pathogenicity analysis,and histopathological observations were carried out.[Results]The Streptococcus strain isolated from infected pigs was identified as Streptococcus suis type 2,which was named TA01 strain.TA01 strain reached the growth peak at 6-8 h post-incubation,and viable counts gradually declined after 8 h of incubation.The correlation equation between OD 600 values and viable counts is y=24.659 x-1.076 1,R^2=0.996 7.TA01 strain was sensitive to penicillin,erythromycin,florfenicol and oxacillin,and resistant to ciprofloxacin,polymyxin B and clindamycin.According to the results of pathogenicity analysis,all the mice in 3.6×10^9 cfu/mouse group died within 48,and these dead mice exhibited acute pyaemia septica.Based on the Reed-Muench formula,it was calculated that LD 50 of TA01 strain was 1.137×10^8 cfu/mouse.Pathological examination showed obvious blue-stained bacteria clusters,accompanied by neutrophil infiltration.[Conclusions]TA01 strain was a virulent strain of Streptococcus suis type 2.Compared with Streptococcus strains which were isolated and reported in China,TA01 strain exhibited strong virulence and rapid proliferation.
基金financially supported by National Key Research and Development Program of China,China(2021YFC3200104)National Natural Science Foundation of China(41773085 and 41977364)+2 种基金Beijing Outstanding Talent Training Programsupported by the“High Level Foreign Experts”program(#GDT20143200016)funded by the State Administration of Foreign Experts Affairs,China,to Nanjing Universitythe Einstein Professor Programof the Chinese Academy of Sciences.
文摘Organophosphate esters(OPEs)are widespread in various environmental media,and can disrupt thyroid endocrine signaling pathways.Mechanisms by which OPEs disrupt thyroid hormone(TH)signal transduction are not fully understood.Here,we present in vivo-in vitro-in silico evidence establishing OPEs as environmental THs competitively entering the brain to inhibit growth of zebrafish via multiple signaling pathways.OPEs can bind to transthyretin(TTR)and thyroxine-binding globulin,thereby affecting the transport of TH in the blood,and to the brain by TTR through the blood-brain barrier.When GH3 cells were exposed to OPEs,cell proliferation was significantly inhibited given that OPEs are competitive inhibitors of TH.Cresyl diphenyl phosphate was shown to be an effective antagonist of TH.Chronic exposure to OPEs significantly inhibited the growth of zebrafish by interfering with thyroperoxidase and thyroglobulin to inhibit TH synthesis.Based on comparisons of modulations of gene expression with the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases,signaling pathways related to thyroid endocrine functions,such as receptor-ligand binding and regulation of hormone levels,were identified as being affected by exposure to OPEs.Effects were also associated with the biosynthesis and metabolism of lipids,and neuroactive ligand-receptor interactions.These findings provide a comprehensive understanding of the mechanisms by which OPEs disrupt thyroid pathways in zebrafish.
