Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different...Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different organs,S.suis 2 must colonize the host,break the blood barrier,and cause exaggerated inflammation.In the last few years,most studies have focused on a single virulence factor and its influences on the host.Membrane vesicles(MVs)can be actively secreted into the extracellular environment contributing to bacteria-host interactions.Gram-negative bacteria-derived outer membrane vesicles(OMVs)were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide(LPS),causing host cell pyroptosis.However,little is known about the effect of the MVs from S.suis 2(Gram-positive bacteria without LPS)on cell pyroptosis.Thus,we investigated the molecular mechanism by which S.suis 2 MVs participate in endothelial cell pyroptosis.In this study,we used proteomics,electron scanning microscopy,fluorescence microscope,Western blotting,and bioassays,to investigate the MVs secreted by S.suis 2.First,we demonstrated that S.suis 2 secreted MVs with an average diameter of 72.04 nm,and 200 proteins in MVs were identified.Then,we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.The S.suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway,resulting in cell pyroptosis,but it did not activate the Caspase-4/-5 pathway.More importantly,endothelial cells produce large amounts of reactive oxygen species(ROS)and lost their mitochondrial membrane potential under induction by S.suis 2 MVs.The results in this study suggest for the first time that MVs from S.suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage,which produced mtDNA and ROS under induction,leading to the pyroptosis of endothelial cells.展开更多
Cells are surrounded by a double-layered phospholipid cell membrane responsible for the isolation of intracellular contents, active regulation of uptake from the extracellular environment, and intercellular connection...Cells are surrounded by a double-layered phospholipid cell membrane responsible for the isolation of intracellular contents, active regulation of uptake from the extracellular environment, and intercellular connection and communication. These cell membranes must be intact and functionally active for cell survival and biological functioning. Compromised damage repair mechanisms usually result in impaired cellular homeostasis, leading to early or late problems. Chronic myopathies, certain myocardial diseases, aging, and acute or chronic neurodegenerative diseases (like Parkinson and Alzheimer) are directly related to cell membrane damage. This study examined the effect of a cholesterol-loaded nanoparticle (methyl-beta cyclodextrin) or the silk protein sericin on cell membrane and DNA integrity and cell viability in an in vitro cell damage model (frozen-thawed rabbit sperm cells). The cells were stored in liquid nitrogen (-196°C), thawed in small batches, and treated with cholesterol-loaded cyclodextrin or sericin before incubation at 35°C for 4 hours. Cell membrane integrity, DNA damage, and viability rates were assessed immediately after thawing and after the incubation period. The administration of sericin and cholesterol in a cell damage model increased cell survival and reduced DNA damage over a 4-hour post-thaw incubation period, suggesting their potential use as a “first aid” intervention at the cellular level.展开更多
This study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of lab...This study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of laboratory mice was investigated. C57BL/6 mice （n = 7） were housed in a microclimate chamber at 37℃-38℃ for 8 h per day for three consecutive days, while control mice （n = 7） were kept at 23℃-24℃. Cauda epididymal spermatozoa were obtained 16 h after the last heat treatment. The results showed that sperm numbers were similar in the two groups （P = 0.23）, but after heat treatment, a significant reduction in the percentage of motile sperm was present （P 〈 0.0001）. Membrane changes of the spermatozoa were investigated by staining with phycoerythrin （PE）- conjugated Annexin V, which detects exteriorization of phosphotidylserine from the inner to the outer leaflet of the sperm plasma membrane, and 7-aminoactinomycin D （7-AAD）, which binds to the sperm nucleus when the plasma membrane is damaged. The percentage of spermatozoa showing positive staining with Annexin V-PE or 7-AAD or both, was significantly higher （P 〈 0.05） in heat-exposed mice compared with controls. These results show that whole-body heat exposure to 37℃-38℃ induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.展开更多
We show that the cytotoxic effect of carbon nanotubes (CNTs) on bacteria is mediated by mechanical damage to the cell wall and membrane. Two β-galactosidase-producing strains of Escherichia coli harboringgenomically ...We show that the cytotoxic effect of carbon nanotubes (CNTs) on bacteria is mediated by mechanical damage to the cell wall and membrane. Two β-galactosidase-producing strains of Escherichia coli harboringgenomically integrated reporter gene constructs, namely pchbB:lacZand prpoS:lacZ, were used for the purpose. We first verified that CNTs result in an inhibition of cell growth. Enzyme activity was determined using a reporter gene assay in which CNTs were used without the lysis buffer (containing detergent). β-galactosidase activity in the presence of CNTs alone measured several fold more than the controls used (without nanotubes). This suggests that CNTs damage the cell membrane in a manner similar to the detergent in the lysis buffer and render E. coli cell walls porous, causing cell contents including enzymes to leak out into the medium. Our results support the hypothesis that mechanical damage to bacterial cell membranes is the prevailing cause of CNT-cytotoxicity.展开更多
Traditional culture methods may underestimate the tolerance of microorganisms to disinfectants because of the existence of viable but nonculturable or sublethally injured cells after disinfection.The selection of a st...Traditional culture methods may underestimate the tolerance of microorganisms to disinfectants because of the existence of viable but nonculturable or sublethally injured cells after disinfection.The selection of a strict method is crucial for the evaluation of disinfection performance.The actions of 2 typical disinfectants–ultraviolet（UV）and chlorine–on the fecal indicator Escherichia coli were investigated by the detection of culturability,membrane permeability,metabolic activity,deoxyribonucleic acid（DNA）,and messenger ribonucleic acid（m RNA）.During UV disinfection,the irreversible damages in the cell membrane and cellular adenosine triphosphate（ATP）were negligible at low UV doses（80 m J/cm^2）.However,membrane permeability was damaged at low doses of chlorine（5 mg/L）,leading to leakage of cellular ATP.Our study showed that a slight lesion in DNA was detected even at high doses of UV（400 m J/cm^2）and chlorine（5 mg/L）treatments.The decay of m RNA was more rapid than that of DNA.The degradation level of m RNA depended on the choice of target genes.After exposure to 50 m J/cm^2UV dose or 5 mg/L chlorine for30 min,the DNA damage repair function（Rec A m RNA）was inhibited.The m RNA involved in the DNA damage repair function can be a potential indicator of bacterial viability.展开更多
Laser Raman spectroscopy was used to investigate the photodamage characteristics of human erythrocyte membranes sensitized by hypocrellin B (HB) at the molecular level. It brought to light that the essence of the chan...Laser Raman spectroscopy was used to investigate the photodamage characteristics of human erythrocyte membranes sensitized by hypocrellin B (HB) at the molecular level. It brought to light that the essence of the changes of erythrocyte membranes’ functions caused by membrane protein cross linking and membrane lipid peroxidation, including increase of fluidity and ion permeability of membranes, etc., was that the orderly structure of erythrocyte membranes had been damaged by the active oxygen ( 1O 2, O 2 .- and .OH) generated by HB, including the decrease of α helix, β sheet and the increase of random coil in the main chain of membrane proteins, the decrease of mercapto groups, indole rings, p hydroxy phenyl rings, monosubstituted phenyl rings, etc. in the side chain, and the changes of the conformations of membrane lipids as well. With the increase of the irradiation time, the trans conformation of membrane lipids increased first, then decreased. On the contrary, the gauche conformation decreased first, then increased. In addition, the decrease of the intensities of the lines assigned to bending vibration of the conformation insensitive CH 2 and CH 3 of membrane proteins and lipids suggested that break of their chains had occurred.展开更多
To treat leaf discs with solutions of various osmotic potentials of polyethylene glycols (MW 6000) by adopting the floating treatment could increase the membrane permeability, decrease the formation of malondialdehyde...To treat leaf discs with solutions of various osmotic potentials of polyethylene glycols (MW 6000) by adopting the floating treatment could increase the membrane permeability, decrease the formation of malondialdehyde,and reduce the activity of peroxidase. Nevertheless, the activities of superoxide dismutase and catalase were not obviously altered. In verifying if the membrane damage was caused by lipid peroxidation initiated by active oxygen species, diethyldithiocarbamate was chosen as inhibitor superoxide dismutase,aminotriazole as catalase and mannitol as scavenger of hydroxyl free radicals.The results have shown that there is not any correlation between lipid peroxidation and membrane damage.Therefore,membrane damage caused by water stress is probably not due to free radical initiation.展开更多
Environmental stress factors could lead to the excess generation of reactive oxygen species（ROS） that induces various forms of skin damage related to oxidative stress. Polyhydroxylated fullerene derivative C（60）...Environmental stress factors could lead to the excess generation of reactive oxygen species（ROS） that induces various forms of skin damage related to oxidative stress. Polyhydroxylated fullerene derivative C（60）（OH）n, acting as an effective agent for prevention of skin aging, is widely used in the lotion and sunscreens in the field of cosmetics, but rarely used in the masks. In this study, we prepared C（60）（OH）n loaded nanofibrous membranes to protect human keratinocyte cells from ROS-associated damage and suppress the elevation of intracellular ROS and Ca（2＋） along with the apoptotic cell death. Two FDAapproved biodegradable polymers, PLGA and PCL, have been used for making the electrospun nanofibers,with C（60）（OH）n added to the polymers as an antioxidant. The nanofibrous membranes with good biocompatibility might be potentially applied in clinical practice to reduce skin aging.展开更多
基金supported by the National Natural Science Foundation of China(U22A20520)the Innovation Team Project of Modern Agricultural Industrial Technology System of Guangdong Province,China(2023KJ119)the Natural Science Foundation Program of Guangdong Province,China(2023A1515012206)。
文摘Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different organs,S.suis 2 must colonize the host,break the blood barrier,and cause exaggerated inflammation.In the last few years,most studies have focused on a single virulence factor and its influences on the host.Membrane vesicles(MVs)can be actively secreted into the extracellular environment contributing to bacteria-host interactions.Gram-negative bacteria-derived outer membrane vesicles(OMVs)were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide(LPS),causing host cell pyroptosis.However,little is known about the effect of the MVs from S.suis 2(Gram-positive bacteria without LPS)on cell pyroptosis.Thus,we investigated the molecular mechanism by which S.suis 2 MVs participate in endothelial cell pyroptosis.In this study,we used proteomics,electron scanning microscopy,fluorescence microscope,Western blotting,and bioassays,to investigate the MVs secreted by S.suis 2.First,we demonstrated that S.suis 2 secreted MVs with an average diameter of 72.04 nm,and 200 proteins in MVs were identified.Then,we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.The S.suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway,resulting in cell pyroptosis,but it did not activate the Caspase-4/-5 pathway.More importantly,endothelial cells produce large amounts of reactive oxygen species(ROS)and lost their mitochondrial membrane potential under induction by S.suis 2 MVs.The results in this study suggest for the first time that MVs from S.suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage,which produced mtDNA and ROS under induction,leading to the pyroptosis of endothelial cells.
文摘Cells are surrounded by a double-layered phospholipid cell membrane responsible for the isolation of intracellular contents, active regulation of uptake from the extracellular environment, and intercellular connection and communication. These cell membranes must be intact and functionally active for cell survival and biological functioning. Compromised damage repair mechanisms usually result in impaired cellular homeostasis, leading to early or late problems. Chronic myopathies, certain myocardial diseases, aging, and acute or chronic neurodegenerative diseases (like Parkinson and Alzheimer) are directly related to cell membrane damage. This study examined the effect of a cholesterol-loaded nanoparticle (methyl-beta cyclodextrin) or the silk protein sericin on cell membrane and DNA integrity and cell viability in an in vitro cell damage model (frozen-thawed rabbit sperm cells). The cells were stored in liquid nitrogen (-196°C), thawed in small batches, and treated with cholesterol-loaded cyclodextrin or sericin before incubation at 35°C for 4 hours. Cell membrane integrity, DNA damage, and viability rates were assessed immediately after thawing and after the incubation period. The administration of sericin and cholesterol in a cell damage model increased cell survival and reduced DNA damage over a 4-hour post-thaw incubation period, suggesting their potential use as a “first aid” intervention at the cellular level.
文摘This study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of laboratory mice was investigated. C57BL/6 mice （n = 7） were housed in a microclimate chamber at 37℃-38℃ for 8 h per day for three consecutive days, while control mice （n = 7） were kept at 23℃-24℃. Cauda epididymal spermatozoa were obtained 16 h after the last heat treatment. The results showed that sperm numbers were similar in the two groups （P = 0.23）, but after heat treatment, a significant reduction in the percentage of motile sperm was present （P 〈 0.0001）. Membrane changes of the spermatozoa were investigated by staining with phycoerythrin （PE）- conjugated Annexin V, which detects exteriorization of phosphotidylserine from the inner to the outer leaflet of the sperm plasma membrane, and 7-aminoactinomycin D （7-AAD）, which binds to the sperm nucleus when the plasma membrane is damaged. The percentage of spermatozoa showing positive staining with Annexin V-PE or 7-AAD or both, was significantly higher （P 〈 0.05） in heat-exposed mice compared with controls. These results show that whole-body heat exposure to 37℃-38℃ induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.
文摘We show that the cytotoxic effect of carbon nanotubes (CNTs) on bacteria is mediated by mechanical damage to the cell wall and membrane. Two β-galactosidase-producing strains of Escherichia coli harboringgenomically integrated reporter gene constructs, namely pchbB:lacZand prpoS:lacZ, were used for the purpose. We first verified that CNTs result in an inhibition of cell growth. Enzyme activity was determined using a reporter gene assay in which CNTs were used without the lysis buffer (containing detergent). β-galactosidase activity in the presence of CNTs alone measured several fold more than the controls used (without nanotubes). This suggests that CNTs damage the cell membrane in a manner similar to the detergent in the lysis buffer and render E. coli cell walls porous, causing cell contents including enzymes to leak out into the medium. Our results support the hypothesis that mechanical damage to bacterial cell membranes is the prevailing cause of CNT-cytotoxicity.
基金supported by the National Natural Science Foundation of China (No. 51578441)the National Program of Water Pollution Control (No. 2013ZX07310-001)+2 种基金the Scientific Research Program funded by the Shaanxi Provincial Education Department (No. 15JK1442)the National Key Technology Support Program (No. 2014BAC13B06)the Program for Innovative Research Team in Shaanxi Province (No. 2013KCT-13)
文摘Traditional culture methods may underestimate the tolerance of microorganisms to disinfectants because of the existence of viable but nonculturable or sublethally injured cells after disinfection.The selection of a strict method is crucial for the evaluation of disinfection performance.The actions of 2 typical disinfectants–ultraviolet（UV）and chlorine–on the fecal indicator Escherichia coli were investigated by the detection of culturability,membrane permeability,metabolic activity,deoxyribonucleic acid（DNA）,and messenger ribonucleic acid（m RNA）.During UV disinfection,the irreversible damages in the cell membrane and cellular adenosine triphosphate（ATP）were negligible at low UV doses（80 m J/cm^2）.However,membrane permeability was damaged at low doses of chlorine（5 mg/L）,leading to leakage of cellular ATP.Our study showed that a slight lesion in DNA was detected even at high doses of UV（400 m J/cm^2）and chlorine（5 mg/L）treatments.The decay of m RNA was more rapid than that of DNA.The degradation level of m RNA depended on the choice of target genes.After exposure to 50 m J/cm^2UV dose or 5 mg/L chlorine for30 min,the DNA damage repair function（Rec A m RNA）was inhibited.The m RNA involved in the DNA damage repair function can be a potential indicator of bacterial viability.
文摘Laser Raman spectroscopy was used to investigate the photodamage characteristics of human erythrocyte membranes sensitized by hypocrellin B (HB) at the molecular level. It brought to light that the essence of the changes of erythrocyte membranes’ functions caused by membrane protein cross linking and membrane lipid peroxidation, including increase of fluidity and ion permeability of membranes, etc., was that the orderly structure of erythrocyte membranes had been damaged by the active oxygen ( 1O 2, O 2 .- and .OH) generated by HB, including the decrease of α helix, β sheet and the increase of random coil in the main chain of membrane proteins, the decrease of mercapto groups, indole rings, p hydroxy phenyl rings, monosubstituted phenyl rings, etc. in the side chain, and the changes of the conformations of membrane lipids as well. With the increase of the irradiation time, the trans conformation of membrane lipids increased first, then decreased. On the contrary, the gauche conformation decreased first, then increased. In addition, the decrease of the intensities of the lines assigned to bending vibration of the conformation insensitive CH 2 and CH 3 of membrane proteins and lipids suggested that break of their chains had occurred.
文摘To treat leaf discs with solutions of various osmotic potentials of polyethylene glycols (MW 6000) by adopting the floating treatment could increase the membrane permeability, decrease the formation of malondialdehyde,and reduce the activity of peroxidase. Nevertheless, the activities of superoxide dismutase and catalase were not obviously altered. In verifying if the membrane damage was caused by lipid peroxidation initiated by active oxygen species, diethyldithiocarbamate was chosen as inhibitor superoxide dismutase,aminotriazole as catalase and mannitol as scavenger of hydroxyl free radicals.The results have shown that there is not any correlation between lipid peroxidation and membrane damage.Therefore,membrane damage caused by water stress is probably not due to free radical initiation.
基金financially supported by the project Electro Med(No.11-115313) from the Danish Council for Strategic Researchthe National Science Fund for Excellent Young Scholars(No.31622026)+2 种基金the National Natural Science Foundation of China(Nos.U1532122,11435002,21471044)the National Key Research and Development Plan(Nos.2016YFA0201600,2016YFA0203204)CAS Youth Innovation Promotion Association(No.2014031)
文摘Environmental stress factors could lead to the excess generation of reactive oxygen species（ROS） that induces various forms of skin damage related to oxidative stress. Polyhydroxylated fullerene derivative C（60）（OH）n, acting as an effective agent for prevention of skin aging, is widely used in the lotion and sunscreens in the field of cosmetics, but rarely used in the masks. In this study, we prepared C（60）（OH）n loaded nanofibrous membranes to protect human keratinocyte cells from ROS-associated damage and suppress the elevation of intracellular ROS and Ca（2＋） along with the apoptotic cell death. Two FDAapproved biodegradable polymers, PLGA and PCL, have been used for making the electrospun nanofibers,with C（60）（OH）n added to the polymers as an antioxidant. The nanofibrous membranes with good biocompatibility might be potentially applied in clinical practice to reduce skin aging.
