Among more than 75 variants of microcystin （MC）, microcystin-LR （MC-LR） is one of the most common toxins. In this study, the feasibility of using Caenorhabditis elegans to evaluate MC-LR toxicity was studied. C. e...Among more than 75 variants of microcystin （MC）, microcystin-LR （MC-LR） is one of the most common toxins. In this study, the feasibility of using Caenorhabditis elegans to evaluate MC-LR toxicity was studied. C. elegans was treated with MC-LR at different concentrations ranging from 0.1 to 80 μg/L. The results showed that MC-LR could reduce lifespan, delay development, lengthen generation time, decrease brood size, suppress locomotion behavior, and decreases hsp-16-2-gfp expression. The endpoints of generation time, brood size, and percentage of the population expressing hsp-16-2-gfp were very sensitive to 1.0μg/L of MC-LR, and would be more useful for the evaluation of MC-LR toxicity. Furthermore, the tissue-specific hsp-16-2-gfp expressions were investigated in MC-LR-exposed animals, and the nervous system and intestine were primarily affected by MC-LR. Therefore, the generation time, brood size, and hsp-16-2-gfp expression in C. elegans can be explored to serve as valuable endpoints for evaluating the potential toxicity from MC-LR exposure.展开更多
Different temperatures of water bath was used to extract the intracellular microcystin-LR(MC-LR) of Microcystis aeruginosa. Researching the extraction efficiency under the suitable temperature, so that it could find o...Different temperatures of water bath was used to extract the intracellular microcystin-LR(MC-LR) of Microcystis aeruginosa. Researching the extraction efficiency under the suitable temperature, so that it could find out the best temperature and time for extracting MC-LR from Microcystis aeruginosa cells. Five equal Microcystis aeruginosa was used to find out the best temperature, extracting at 60℃, 70℃, 80℃, 90℃ and 100℃ for 15 minutes, respectively. Results showed that the content of MC-LR extracted with the water under 100℃ was the highest. But meanwhile, the type and the content of impurities was the highest, too. In addition, another six equal Microcystis aeruginosa was extract with the water under 100℃ for 5min, 10 min, 15 min, 20 min, 25 min and 30 min respectively. It was proved that 20 minutes was enough for extracting MC-LR from Microcystis aeruginosa, no long time was needed.展开更多
This study investigates the photocatalytic degradation of microcystin-LR (MC-LR) under simulated solar light using Pt modified nano-sized tungsten trioxides (Pt/WO3). Photocatalytic activity was higher during the degr...This study investigates the photocatalytic degradation of microcystin-LR (MC-LR) under simulated solar light using Pt modified nano-sized tungsten trioxides (Pt/WO3). Photocatalytic activity was higher during the degradation of MC-LR with Pt/WO 3 than with pure WO 3 or Ti O2 . The catalyst loading greatly affect the degradation performance. The rate of degradation is influenced by the initial pH of the reaction solution. This study also investigates the photocatalytic inactivation of cyanobacteria. The results show that the algal growth was successfully controlled by the Pt/W O 3 . This study suggests Pt/W O 3 photocatalytic oxidation with solar light is a promising treatment for water containing MC-LR.展开更多
In this study, we report on the degradation of microcystin-LR （MC-LR） by gas- liquid interracial discharge plasma. The influences of operation parameters such as average input voltage, electrode distance and gas flo...In this study, we report on the degradation of microcystin-LR （MC-LR） by gas- liquid interracial discharge plasma. The influences of operation parameters such as average input voltage, electrode distance and gas flow rate are investigated. Experimental results indicate that the input voltage and gas flow rate have positive influences on MC-LR degradation, while the electrode distance has a negative one. After 6 min discharge with 25 kV average input voltage and 60 L/h air aerati by discharge both in on, the degradation rate of MC-LR achieves 75.3%. distilled water and MC-LR solution are measured H202 and 03 generated Moreover, an emission spectroscopy is used as an indicator of the processes that take place on the gas-liquid boundary and inside plasma. Varied types of radicals （O, .OH, CO, 03, etc.） are proved to be present in the gas phase during gas-liquid interfacial discharge.展开更多
Objective:We explored the role and molecular mechanism of Microcystin-LR(MC-LR) in hepatocarcinogenesis.Methods:The two-stage-medium-term theory was applied to the establishment of the animal model.The promoting effec...Objective:We explored the role and molecular mechanism of Microcystin-LR(MC-LR) in hepatocarcinogenesis.Methods:The two-stage-medium-term theory was applied to the establishment of the animal model.The promoting effect of MC-LR on liver tumor was evaluated with the Albert γ-GT methods.During the tumor-promoting course,the effects of MC-LR on the regulation and expression of the Bcl-2 and Bax genes were studied with immunohistochemical technique and RT-PCR.Results:MCLR could enhance the positive reaction of Albert γ-GT(GGT),a preneoplasm marker.The positive reaction rate of GGT in diethylnitrosamine(DEN) + MC group was significantly higher than that in the DEN control group.The protein and RNA expression of Bcl-2 was significantly increased by MC-LR,and that the protein expression of Bax was decreased simultaneously.Conclusion:These results indicate that the MC-LR can inhabit apoptosis through the Bcl-2 and Bax genes.Therefore,we conclude that the expression change of Bcl-2 and Bax genes possibly plays an important role in the promotion of liver tumor by MC-LR.展开更多
Microcystins （ MCs ） are well known as hepatotoxins produced by blooms of toxic cyanobacteria （blue-green algae） abundant in surface water used as drinking water resource and have drawn attention of environmentali...Microcystins （ MCs ） are well known as hepatotoxins produced by blooms of toxic cyanobacteria （blue-green algae） abundant in surface water used as drinking water resource and have drawn attention of environmentalists world over by leading to adverse health effects. A study on efficiency and reaction kinetics of microcystin-LR （ MC-LR ） degradation by CIO2 was performed. Experimental results indicated that MC-LR was removed by CIO2 effectively and the residual concentration of MC-LR could meet the national guideline（GB5749 - 2006） （1.0 μg · L^-1）, the efficiency of removal was in positive correlation to CIO2 dosage and reaction time and in negative correlation to initial concentration of MC-LR and pH value, whereas it was affected by temperature slightly. CIO2 dosage was the most important reaction factor on base of the orthogonal test results. The reaction was second order overall and first order with respect to both CIO2 and MC- LR, and had an activation energy of 78.81 kJ · mo1^-1 . The reaction rate constant was 4.74× 10-^2 L/（mol · min） at 10 ℃. Therefore, oxidation of CIO~ could be taken as an effective technology for removing MC-LR from drinking water resources in traditional drinking water supplies.展开更多
Photochemical reactions of microcystin-LR, a toxic compound produced by some blue green algae, were investigated. Ultraviolet absorption of microcystin-LR was assessed. Time-dependent density functional theory (TDDFT)...Photochemical reactions of microcystin-LR, a toxic compound produced by some blue green algae, were investigated. Ultraviolet absorption of microcystin-LR was assessed. Time-dependent density functional theory (TDDFT) calculations indicated that absorption peak at 238 nm was mainly due to excitation of electrons from the linear chain structure Adda of microcystin-LR. Irradiation of microcystin-LR with UV light resulted in the reduction of the 238 nm absorption peak and the appearance of a new peak at 300 nm. Density functional theory (DFT) and TDDFT calculations with a model molecule suggested that this 300 nm peak was due to tricyclo-Adda microcystin-LR, an intermediate in photochemical reactions of microcystin-LR. Analysis of the rate of this photochemical reaction showed that it was a first order reaction.展开更多
Microcystins(MCs),a family of cyclic heptapeptide cyanotoxins,exists in aquatic environment where cyanobacterial bloom happens,which will accumulate in aquatic organisms and transfer through the food chain to higher t...Microcystins(MCs),a family of cyclic heptapeptide cyanotoxins,exists in aquatic environment where cyanobacterial bloom happens,which will accumulate in aquatic organisms and transfer through the food chain to higher trophic levels,posing a health risk to both animals and human bodies.Among various MCs,Microcystin-LR(MC-LR)is worthiest studied for its strong toxicity,ubiquity and widespread.Here in this work,iminodiacetic acid(IDA)decorated magnetic mesoporous silica(mSiO_(2))nanocomposites(Fe_(3)O_(4)@mSiO_(2)-IDA)were facilely synthesized which possessed the merits of large surface area(188.21 m^(2)/g),accessible porosity(2.66 nm),excellent hydrophilicity and rapid responsiveness to magnetic field.Then the composites were successfully employed to the removal process of Microcystin-LR in real water samples followed by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS)analysis,achieving the removal efficiency above 92.5%even after ten recycles of the composites.It provided a potential method for removing MC-LR in aqueous environment with high effectiveness,lower costs and less secondary contamination.展开更多
Microcystin-LR(MC-LR),the most prevalent and diverse cyanotoxin produced by harmful cyanobacterial blooms,has been linked to gastrointestinal toxicity.Therefore,we conducted a case-control study across four regions in...Microcystin-LR(MC-LR),the most prevalent and diverse cyanotoxin produced by harmful cyanobacterial blooms,has been linked to gastrointestinal toxicity.Therefore,we conducted a case-control study across four regions in China to investigate this relationship.Inflammatory bowel disease(IBD)cases(219)were matched with healthy controls(438)based on age and gender and conditional logistic regression models and Restricted cubic splines were used to evaluate the association between MC-LR exposure and IBD risk.We used quantitative real-time polymerase chain reaction to measure the expression levels of inflammatory factors.The levels of protein expression in the colorectum were determined using Western blotting(WB).Compared to the lowest quartile of serum MC-LR levels,the adjusted odds ratios and 95%confidence intervals(CI)for the highest quartiles of serum MC-LR levels were 5.51(2.70,11.21).The RCS was shown the association between serum MC-LR levels and IBD risk was nonlinear(Pnonlinear<0.001).In the animal experiments,MC-LR resulted in colorectal injury via the PI3K/AKT signaling pathway.Our study provides the evidence that serum MC-LR exposure is significantly associated with the risk of IBD in China.Animal study results indicate that MC-LR probably causes IBD via the PI3K/AKT signaling pathway.展开更多
N-doped nano-crystalline TiO2 powders have been synthesized by the sol-gel method.The shape and crystal structure of the resulting N-doped TiO2 were investigated by X-ray Photoelectron Spectroscopy (XPS),X-ray spectro...N-doped nano-crystalline TiO2 powders have been synthesized by the sol-gel method.The shape and crystal structure of the resulting N-doped TiO2 were investigated by X-ray Photoelectron Spectroscopy (XPS),X-ray spectroscopy (XRD),Transmission Electron Microscopy (TEM) and UV-vis reflection spectrum.The results showed that doping TiO2 with nitrogen can lower its band gap and apparently shift its optical response to the visible region.Under the visible light (λ】 420 nm) irradiation,the MC-LR was degraded by the synthesized N-TiO2 nano-material.The variation of MC-LR amount and its intermediates were detected by high performance liquid chromatography (HPLC) and LC-MS,respectively.The mineralization of MC-LR was determined by total organic carbon (TOC) analysis.Simultaneously,transient oxidative species generated during photocatalysis were tracked by electron spin resonance (ESR) and Peroxidase method.All these results indicated that visible-light excited N-TiO2 can activate molecular oxygen and thereby achieve degradation of MC-LR completely within 14 h.The removal of 59% of TOC was achieved after 20 h irradiation.The major oxidative species in the system were hydroxyl radical (·OH) and H2O2.13 Kinds of intermediates were primarily identified in the process.Based on these results,a reasonable conclusion was drawn for the degradation of MC-LR wherein its four positions are easy to be attacked by the photo-generated OH radical followed by the hydrolyzation of peptides.展开更多
A new kind of low-cost syntactic adsorbent from bamboo charcoal and chitosan was developed for the removal of microcystin-LR from drinking water. Removal effciency was higher for the syntactic adsorbent when the amoun...A new kind of low-cost syntactic adsorbent from bamboo charcoal and chitosan was developed for the removal of microcystin-LR from drinking water. Removal effciency was higher for the syntactic adsorbent when the amount of bamboo charcoal was increased. The optimum dose ratio of bamboo charcoal to chitosan was 6：4, and the optimum amount was 15 mg/L; equilibrium time was 6 hr. The adsorption isotherm was non-linear and could be simulated by the Freundlich model （R2 = 0.9337）. Adsorption efficiency was strongly afflected by pH and natural organic matter （NOM）. Removal efficiency was 16% higher at pH 3 than at pH 9. Efficiency rate was reduced by 15% with 25 mg/L NOM （UV254 = 0.089 cm-1） in drinking water. This study demonstrated that the bamboo charcoal modified with chitosan can effectively remove microcystin-LR from drinking water.展开更多
Due to their toxicity,the increased distribution of microcystins(MCs) has become an important worldwide problem.MCs have been recognized as inhibitors of protein phosphatase 2A(PP2A) through their binding to the PP2A ...Due to their toxicity,the increased distribution of microcystins(MCs) has become an important worldwide problem.MCs have been recognized as inhibitors of protein phosphatase 2A(PP2A) through their binding to the PP2A catalytic subunit.However,the exact mechanism of MC toxicity has not been elucidated,especially concerning the cellular response and its autoregulation.To further dissect the role of PP2A in MC-induced toxicity,the present study was undertaken to determine the response of PP2A in human amniotic epithelial(FL) cells treated with microcystin-LR(MCLR),one of the MC congeners.The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity,and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A,as expected.The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A.Furthermore,MCLR altered microtubule post-translational modifications through PP2A.These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.展开更多
In this study,a point-of-care sensing protocol has been reported for rapid and sensitive detection of Microcystin-LR(MC-LR)in water by personal glucose meter.The proposed immunosensor has been fabricated by using a pr...In this study,a point-of-care sensing protocol has been reported for rapid and sensitive detection of Microcystin-LR(MC-LR)in water by personal glucose meter.The proposed immunosensor has been fabricated by using a primary antibody coated ZnFe2O4 nanoparticles to capture the target MC-LR.Consequently,the invertase@secondary antibody-conjugated graphene oxide-Au NPs can be immobilized for formating the sandwich immuno-complexes,which allowed for enzymatic conversion of sucrose to glucose.Thus,the concentration of MC-LR can be refelected by the converted glucose,which can be easily measured by the personal glucose meter(PGM).The PGM readout immunosensing method possessed good reproducibility and stability,which may have significant potential for other applications.展开更多
An electrochemical immunosensor was developed for ultrasensitive detection of microcystin-LR in water. MIL-101, a porous metal-organic frameworks(MOFs) material based on trivalent chromium skeleton were synthesized by...An electrochemical immunosensor was developed for ultrasensitive detection of microcystin-LR in water. MIL-101, a porous metal-organic frameworks(MOFs) material based on trivalent chromium skeleton were synthesized by hydrothermal synthesis method, and loaded with Au nanoparticles(Au NPs) to prepare Au NPs@MIL-101 composite materials which were used as a marker to label anti microcystin-LR(Anti-MC-LR). The composite materials have strong catalytic properties to the oxidation of ascorbic acid. Anti-MC-LR was immobilized on glassy carbon electrode surface using electrodeposition graphene oxide(GO) as an immobilization matrix to construct a competitive microcystin-LR immunosensor. The electrochemical immunosensor display linear relationship in the range of 0.05 ng/mL-75 μg/mL with linear correlation coefficient of 0.9951 and detection limit of 0.02 ng/mL(S/N = 3). This sensor was used to detect microcystin-LR in the water sample. The recovery was 102.43%,which is satisfied. The good testing results indicate the sensor has a great prospect in practical application.展开更多
The degradation of Microcystin-LR (MC-LR) in water by hydrogen peroxide assisted ultraviolet (UV/H2O2) process was investigated in this paper. The UV/H2O2 process appeared to be effective in removal of the MC-LR. MC-L...The degradation of Microcystin-LR (MC-LR) in water by hydrogen peroxide assisted ultraviolet (UV/H2O2) process was investigated in this paper. The UV/H2O2 process appeared to be effective in removal of the MC-LR. MC-LR decomposition was primarily ascribed to production of strong and nonselective oxidant-hydroxyl radicals within the system. The intensity of UV radiation, initial concentration of MC-LR, MC-LR purity, dosages of H2O2, the initial solution pH, and anions present in water, to some extent, influenced the degradation rate of MC-LR. A modified pseudo-first-order kinetic model was developed to predict the removal efficiency under different experimental conditions.展开更多
A promising bacterial strain for biodegradingmicrocystin-LR(MC-LR)as the sole carbon and nitrogensource was successfully isolated from Lake Dianchi,China.The strain was identified as Sphingopyxis sp.USTB-05,which was ...A promising bacterial strain for biodegradingmicrocystin-LR(MC-LR)as the sole carbon and nitrogensource was successfully isolated from Lake Dianchi,China.The strain was identified as Sphingopyxis sp.USTB-05,which was the first isolated MCs-biodegradingSphingopyxis sp.in China.The average biodegradationrate of MC-LR by Sphingopyxis sp.USTB-05 was 28.8mg·L^(-1)per day,which was apparently higher than those ofother bacteria reported so far.The optimal temperature andpH for both strain USTB-05 growth and MC-LRbiodegradation were 30℃and 7.0,respectively.Therelease of MC-LR from the cyanobacterial cells collectedfrom Lake Guishui and the biodegradation of MC-LR byboth strain and cell-free extract(CE)were investigated.The results indicated that MC-LR with the initialconcentration of 4.0 mg·L^(-1)in water was biodegraded bySphingopyxis sp.USTB-05 within 4 d,while MC-LR withthe initial concentration of 28.8 mg·L^(-1)could be completelyremoved in 3 h by CE of Sphingopyxis sp.USTB-05 containing 350 mg·L^(-1)protein.During enzymaticbiodegradation of MC-LR,two intermediate metabolitesand a dead-end product were observed on an HPLCchromatogram.Moreover,the similar scanning profiles ofMC-LR and its metabolic products indicate that the Addaside-chain of MC-LR was kept intact in all products.展开更多
Microcystin-LR （MC-LR） is the most abundant and toxic microcystin congener and has been classified as a potential human carcinogen （Group 2B） by the International Agency for Research on Cancer. However, the mechan...Microcystin-LR （MC-LR） is the most abundant and toxic microcystin congener and has been classified as a potential human carcinogen （Group 2B） by the International Agency for Research on Cancer. However, the mechanisms underlying the genotoxic effects of MC-LR during chronic exposure are still poorly understood. In the present study, human-hamster hybrid （AL） cells were exposed to MC-LR for varying lengths of time to investigate the role of nitrogen radicals in MC-LR-induced genotoxicity. The mutagenic potential at the CD59 locus was more than 2-fold higher （p 〈 0.01） in AL ceUs exposed to a cytotoxic concentration （1 μmol/L） of MC-LR for 30 days than in untreated control ceils, which was consistent with the formation of micronucleus. MC-LR caused a dose-dependent increase in nitric oxide （NO） production in treated cells. Moreover, this was blocked by concurrent treatment with the NO synthase inhibitor NC-methyl-L-arginine （L-NMMA）, which suppressed MC-LR- induced mutations as well. The survival of mitochondrial DNA-depleted （pO） AL ceils was markedly decreased by MC-LR treatment compared to that in AL cells, while the CD59 mutant fraction was unaltered. These results provided clear evidence that the genotoxicity associated with chronic MC-LR exposure in mammalian cells was mediated by NO and might be considered as a basis for the development of therapeutics that prevent carcinogenesis.展开更多
基金supported by the National Natural Sci-ence Foundation of China (No. 30771113, 30870810)the Doctoral Program of Higher Education of China (No.20050286035)+1 种基金the Jiangsu 333 Project Foundation (No.07056)the Natural Science Foundation of Jiangsu Province (No. BK2006107, BK2008320)
文摘Among more than 75 variants of microcystin （MC）, microcystin-LR （MC-LR） is one of the most common toxins. In this study, the feasibility of using Caenorhabditis elegans to evaluate MC-LR toxicity was studied. C. elegans was treated with MC-LR at different concentrations ranging from 0.1 to 80 μg/L. The results showed that MC-LR could reduce lifespan, delay development, lengthen generation time, decrease brood size, suppress locomotion behavior, and decreases hsp-16-2-gfp expression. The endpoints of generation time, brood size, and percentage of the population expressing hsp-16-2-gfp were very sensitive to 1.0μg/L of MC-LR, and would be more useful for the evaluation of MC-LR toxicity. Furthermore, the tissue-specific hsp-16-2-gfp expressions were investigated in MC-LR-exposed animals, and the nervous system and intestine were primarily affected by MC-LR. Therefore, the generation time, brood size, and hsp-16-2-gfp expression in C. elegans can be explored to serve as valuable endpoints for evaluating the potential toxicity from MC-LR exposure.
文摘Different temperatures of water bath was used to extract the intracellular microcystin-LR(MC-LR) of Microcystis aeruginosa. Researching the extraction efficiency under the suitable temperature, so that it could find out the best temperature and time for extracting MC-LR from Microcystis aeruginosa cells. Five equal Microcystis aeruginosa was used to find out the best temperature, extracting at 60℃, 70℃, 80℃, 90℃ and 100℃ for 15 minutes, respectively. Results showed that the content of MC-LR extracted with the water under 100℃ was the highest. But meanwhile, the type and the content of impurities was the highest, too. In addition, another six equal Microcystis aeruginosa was extract with the water under 100℃ for 5min, 10 min, 15 min, 20 min, 25 min and 30 min respectively. It was proved that 20 minutes was enough for extracting MC-LR from Microcystis aeruginosa, no long time was needed.
文摘This study investigates the photocatalytic degradation of microcystin-LR (MC-LR) under simulated solar light using Pt modified nano-sized tungsten trioxides (Pt/WO3). Photocatalytic activity was higher during the degradation of MC-LR with Pt/WO 3 than with pure WO 3 or Ti O2 . The catalyst loading greatly affect the degradation performance. The rate of degradation is influenced by the initial pH of the reaction solution. This study also investigates the photocatalytic inactivation of cyanobacteria. The results show that the algal growth was successfully controlled by the Pt/W O 3 . This study suggests Pt/W O 3 photocatalytic oxidation with solar light is a promising treatment for water containing MC-LR.
基金supported by National Natural Science Foundation of China(Nos.21006017 and 20906079)Zhejiang Provincial Natural Science Foundation of China(Grant Y5100356)
文摘In this study, we report on the degradation of microcystin-LR （MC-LR） by gas- liquid interracial discharge plasma. The influences of operation parameters such as average input voltage, electrode distance and gas flow rate are investigated. Experimental results indicate that the input voltage and gas flow rate have positive influences on MC-LR degradation, while the electrode distance has a negative one. After 6 min discharge with 25 kV average input voltage and 60 L/h air aerati by discharge both in on, the degradation rate of MC-LR achieves 75.3%. distilled water and MC-LR solution are measured H202 and 03 generated Moreover, an emission spectroscopy is used as an indicator of the processes that take place on the gas-liquid boundary and inside plasma. Varied types of radicals （O, .OH, CO, 03, etc.） are proved to be present in the gas phase during gas-liquid interfacial discharge.
基金Supported by grants from the Natural Science Foundation of Fujian Province (No C0710019)the Science & Technology Program of Fuzhou (No 2006S-G24)
文摘Objective:We explored the role and molecular mechanism of Microcystin-LR(MC-LR) in hepatocarcinogenesis.Methods:The two-stage-medium-term theory was applied to the establishment of the animal model.The promoting effect of MC-LR on liver tumor was evaluated with the Albert γ-GT methods.During the tumor-promoting course,the effects of MC-LR on the regulation and expression of the Bcl-2 and Bax genes were studied with immunohistochemical technique and RT-PCR.Results:MCLR could enhance the positive reaction of Albert γ-GT(GGT),a preneoplasm marker.The positive reaction rate of GGT in diethylnitrosamine(DEN) + MC group was significantly higher than that in the DEN control group.The protein and RNA expression of Bcl-2 was significantly increased by MC-LR,and that the protein expression of Bax was decreased simultaneously.Conclusion:These results indicate that the MC-LR can inhabit apoptosis through the Bcl-2 and Bax genes.Therefore,we conclude that the expression change of Bcl-2 and Bax genes possibly plays an important role in the promotion of liver tumor by MC-LR.
基金the National Nature Science Foundation of China(No.50178022)the National863Projects(No.2006AA06Z309)
文摘Microcystins （ MCs ） are well known as hepatotoxins produced by blooms of toxic cyanobacteria （blue-green algae） abundant in surface water used as drinking water resource and have drawn attention of environmentalists world over by leading to adverse health effects. A study on efficiency and reaction kinetics of microcystin-LR （ MC-LR ） degradation by CIO2 was performed. Experimental results indicated that MC-LR was removed by CIO2 effectively and the residual concentration of MC-LR could meet the national guideline（GB5749 - 2006） （1.0 μg · L^-1）, the efficiency of removal was in positive correlation to CIO2 dosage and reaction time and in negative correlation to initial concentration of MC-LR and pH value, whereas it was affected by temperature slightly. CIO2 dosage was the most important reaction factor on base of the orthogonal test results. The reaction was second order overall and first order with respect to both CIO2 and MC- LR, and had an activation energy of 78.81 kJ · mo1^-1 . The reaction rate constant was 4.74× 10-^2 L/（mol · min） at 10 ℃. Therefore, oxidation of CIO~ could be taken as an effective technology for removing MC-LR from drinking water resources in traditional drinking water supplies.
文摘Photochemical reactions of microcystin-LR, a toxic compound produced by some blue green algae, were investigated. Ultraviolet absorption of microcystin-LR was assessed. Time-dependent density functional theory (TDDFT) calculations indicated that absorption peak at 238 nm was mainly due to excitation of electrons from the linear chain structure Adda of microcystin-LR. Irradiation of microcystin-LR with UV light resulted in the reduction of the 238 nm absorption peak and the appearance of a new peak at 300 nm. Density functional theory (DFT) and TDDFT calculations with a model molecule suggested that this 300 nm peak was due to tricyclo-Adda microcystin-LR, an intermediate in photochemical reactions of microcystin-LR. Analysis of the rate of this photochemical reaction showed that it was a first order reaction.
基金financially supported by National Key R&D Program of China(No.2018YFA0507501)the National Natural Science Foundation of China(Nos.22074019,21425518,22004017,22205085,and 32160305)+2 种基金Key Science and Technology Project of Jiangxi Province(Nos.20213AAG01012 and 2022KSG01004)Water Science and Technology Project of Jiangxi Province(Nos.202124ZDKT19 and 202223YBKT07)Shanghai Sailing Program(No.20YF1405300).
文摘Microcystins(MCs),a family of cyclic heptapeptide cyanotoxins,exists in aquatic environment where cyanobacterial bloom happens,which will accumulate in aquatic organisms and transfer through the food chain to higher trophic levels,posing a health risk to both animals and human bodies.Among various MCs,Microcystin-LR(MC-LR)is worthiest studied for its strong toxicity,ubiquity and widespread.Here in this work,iminodiacetic acid(IDA)decorated magnetic mesoporous silica(mSiO_(2))nanocomposites(Fe_(3)O_(4)@mSiO_(2)-IDA)were facilely synthesized which possessed the merits of large surface area(188.21 m^(2)/g),accessible porosity(2.66 nm),excellent hydrophilicity and rapid responsiveness to magnetic field.Then the composites were successfully employed to the removal process of Microcystin-LR in real water samples followed by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS)analysis,achieving the removal efficiency above 92.5%even after ten recycles of the composites.It provided a potential method for removing MC-LR in aqueous environment with high effectiveness,lower costs and less secondary contamination.
基金National Natural Science Foundation of China(U23A20492)Hunan Province Key Research and Development Projects(2022SK2089)Huxiang Youth Talent Program(2021RC3107).
文摘Microcystin-LR(MC-LR),the most prevalent and diverse cyanotoxin produced by harmful cyanobacterial blooms,has been linked to gastrointestinal toxicity.Therefore,we conducted a case-control study across four regions in China to investigate this relationship.Inflammatory bowel disease(IBD)cases(219)were matched with healthy controls(438)based on age and gender and conditional logistic regression models and Restricted cubic splines were used to evaluate the association between MC-LR exposure and IBD risk.We used quantitative real-time polymerase chain reaction to measure the expression levels of inflammatory factors.The levels of protein expression in the colorectum were determined using Western blotting(WB).Compared to the lowest quartile of serum MC-LR levels,the adjusted odds ratios and 95%confidence intervals(CI)for the highest quartiles of serum MC-LR levels were 5.51(2.70,11.21).The RCS was shown the association between serum MC-LR levels and IBD risk was nonlinear(Pnonlinear<0.001).In the animal experiments,MC-LR resulted in colorectal injury via the PI3K/AKT signaling pathway.Our study provides the evidence that serum MC-LR exposure is significantly associated with the risk of IBD in China.Animal study results indicate that MC-LR probably causes IBD via the PI3K/AKT signaling pathway.
基金supported by the National Natural Science Foundation of China (20877048)the Major State Basic Research Development Program of China (2008CB417206)The Plan of Scientific and Technological Innovation Team of Outstanding Young in Universities of Hubei Province (T200703)
文摘N-doped nano-crystalline TiO2 powders have been synthesized by the sol-gel method.The shape and crystal structure of the resulting N-doped TiO2 were investigated by X-ray Photoelectron Spectroscopy (XPS),X-ray spectroscopy (XRD),Transmission Electron Microscopy (TEM) and UV-vis reflection spectrum.The results showed that doping TiO2 with nitrogen can lower its band gap and apparently shift its optical response to the visible region.Under the visible light (λ】 420 nm) irradiation,the MC-LR was degraded by the synthesized N-TiO2 nano-material.The variation of MC-LR amount and its intermediates were detected by high performance liquid chromatography (HPLC) and LC-MS,respectively.The mineralization of MC-LR was determined by total organic carbon (TOC) analysis.Simultaneously,transient oxidative species generated during photocatalysis were tracked by electron spin resonance (ESR) and Peroxidase method.All these results indicated that visible-light excited N-TiO2 can activate molecular oxygen and thereby achieve degradation of MC-LR completely within 14 h.The removal of 59% of TOC was achieved after 20 h irradiation.The major oxidative species in the system were hydroxyl radical (·OH) and H2O2.13 Kinds of intermediates were primarily identified in the process.Based on these results,a reasonable conclusion was drawn for the degradation of MC-LR wherein its four positions are easy to be attacked by the photo-generated OH radical followed by the hydrolyzation of peptides.
基金supported by the Program for Excellent Young Teachers in Hangzhou Normal University (No.JTAS 2011-01-012)the project of China Postdoctoral Science Foundation (No. 20070421175)the New Talents Plan Program of Zhejiang Province (No. 2010R421005)
文摘A new kind of low-cost syntactic adsorbent from bamboo charcoal and chitosan was developed for the removal of microcystin-LR from drinking water. Removal effciency was higher for the syntactic adsorbent when the amount of bamboo charcoal was increased. The optimum dose ratio of bamboo charcoal to chitosan was 6：4, and the optimum amount was 15 mg/L; equilibrium time was 6 hr. The adsorption isotherm was non-linear and could be simulated by the Freundlich model （R2 = 0.9337）. Adsorption efficiency was strongly afflected by pH and natural organic matter （NOM）. Removal efficiency was 16% higher at pH 3 than at pH 9. Efficiency rate was reduced by 15% with 25 mg/L NOM （UV254 = 0.089 cm-1） in drinking water. This study demonstrated that the bamboo charcoal modified with chitosan can effectively remove microcystin-LR from drinking water.
基金Project supported by the National Natural Science Foundation of China (Nos. 30771827 and 20777067)the Key Special Program on the S & T of China for the Pollution Control and Treatment of Water Bodies (No. 2008ZX07421-001)
文摘Due to their toxicity,the increased distribution of microcystins(MCs) has become an important worldwide problem.MCs have been recognized as inhibitors of protein phosphatase 2A(PP2A) through their binding to the PP2A catalytic subunit.However,the exact mechanism of MC toxicity has not been elucidated,especially concerning the cellular response and its autoregulation.To further dissect the role of PP2A in MC-induced toxicity,the present study was undertaken to determine the response of PP2A in human amniotic epithelial(FL) cells treated with microcystin-LR(MCLR),one of the MC congeners.The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity,and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A,as expected.The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A.Furthermore,MCLR altered microtubule post-translational modifications through PP2A.These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.
基金the Natural Science Foundation of Shandong(No.ZR2017MB017)for the financial support
文摘In this study,a point-of-care sensing protocol has been reported for rapid and sensitive detection of Microcystin-LR(MC-LR)in water by personal glucose meter.The proposed immunosensor has been fabricated by using a primary antibody coated ZnFe2O4 nanoparticles to capture the target MC-LR.Consequently,the invertase@secondary antibody-conjugated graphene oxide-Au NPs can be immobilized for formating the sandwich immuno-complexes,which allowed for enzymatic conversion of sucrose to glucose.Thus,the concentration of MC-LR can be refelected by the converted glucose,which can be easily measured by the personal glucose meter(PGM).The PGM readout immunosensing method possessed good reproducibility and stability,which may have significant potential for other applications.
基金supported by the National Natural Science Foundation of China(Nos. 21165023,21465026, 21765026, 21605130)the National Key Scientific Program of China(Nos. 2011CB911000,01100205020503104)
文摘An electrochemical immunosensor was developed for ultrasensitive detection of microcystin-LR in water. MIL-101, a porous metal-organic frameworks(MOFs) material based on trivalent chromium skeleton were synthesized by hydrothermal synthesis method, and loaded with Au nanoparticles(Au NPs) to prepare Au NPs@MIL-101 composite materials which were used as a marker to label anti microcystin-LR(Anti-MC-LR). The composite materials have strong catalytic properties to the oxidation of ascorbic acid. Anti-MC-LR was immobilized on glassy carbon electrode surface using electrodeposition graphene oxide(GO) as an immobilization matrix to construct a competitive microcystin-LR immunosensor. The electrochemical immunosensor display linear relationship in the range of 0.05 ng/mL-75 μg/mL with linear correlation coefficient of 0.9951 and detection limit of 0.02 ng/mL(S/N = 3). This sensor was used to detect microcystin-LR in the water sample. The recovery was 102.43%,which is satisfied. The good testing results indicate the sensor has a great prospect in practical application.
基金supported by the National Key Technologies Supporting Program of China during the 11th Five-Year Plan Period (No. 2006BAJ08B06)the National Major Project of Science & Technology Ministry of China (No. 2008ZX07421-002)the Shanghai Science & Technology Commission Key Scientific & Technological Project (No. 072312001), China
文摘The degradation of Microcystin-LR (MC-LR) in water by hydrogen peroxide assisted ultraviolet (UV/H2O2) process was investigated in this paper. The UV/H2O2 process appeared to be effective in removal of the MC-LR. MC-LR decomposition was primarily ascribed to production of strong and nonselective oxidant-hydroxyl radicals within the system. The intensity of UV radiation, initial concentration of MC-LR, MC-LR purity, dosages of H2O2, the initial solution pH, and anions present in water, to some extent, influenced the degradation rate of MC-LR. A modified pseudo-first-order kinetic model was developed to predict the removal efficiency under different experimental conditions.
基金The first and second authors did same contribution to this paper.This work was supported by the National Natural Science Foundation of China(Grant No.203777008)State Key Joint Laboratory of Environment Simulation and Pollution Control(No.09K08ESPCT),and Educational Committee of Beijing.
文摘A promising bacterial strain for biodegradingmicrocystin-LR(MC-LR)as the sole carbon and nitrogensource was successfully isolated from Lake Dianchi,China.The strain was identified as Sphingopyxis sp.USTB-05,which was the first isolated MCs-biodegradingSphingopyxis sp.in China.The average biodegradationrate of MC-LR by Sphingopyxis sp.USTB-05 was 28.8mg·L^(-1)per day,which was apparently higher than those ofother bacteria reported so far.The optimal temperature andpH for both strain USTB-05 growth and MC-LRbiodegradation were 30℃and 7.0,respectively.Therelease of MC-LR from the cyanobacterial cells collectedfrom Lake Guishui and the biodegradation of MC-LR byboth strain and cell-free extract(CE)were investigated.The results indicated that MC-LR with the initialconcentration of 4.0 mg·L^(-1)in water was biodegraded bySphingopyxis sp.USTB-05 within 4 d,while MC-LR withthe initial concentration of 28.8 mg·L^(-1)could be completelyremoved in 3 h by CE of Sphingopyxis sp.USTB-05 containing 350 mg·L^(-1)protein.During enzymaticbiodegradation of MC-LR,two intermediate metabolitesand a dead-end product were observed on an HPLCchromatogram.Moreover,the similar scanning profiles ofMC-LR and its metabolic products indicate that the Addaside-chain of MC-LR was kept intact in all products.
基金supported by the National Basic Research Program (973) of China (No. 2014CB932002)the Chinese Academy of Sciences Strategic Priority Research Program (No. XDB14030502)the National Natural Science Foundation of China (Nos. 21177133, U1232144)
文摘Microcystin-LR （MC-LR） is the most abundant and toxic microcystin congener and has been classified as a potential human carcinogen （Group 2B） by the International Agency for Research on Cancer. However, the mechanisms underlying the genotoxic effects of MC-LR during chronic exposure are still poorly understood. In the present study, human-hamster hybrid （AL） cells were exposed to MC-LR for varying lengths of time to investigate the role of nitrogen radicals in MC-LR-induced genotoxicity. The mutagenic potential at the CD59 locus was more than 2-fold higher （p 〈 0.01） in AL ceUs exposed to a cytotoxic concentration （1 μmol/L） of MC-LR for 30 days than in untreated control ceils, which was consistent with the formation of micronucleus. MC-LR caused a dose-dependent increase in nitric oxide （NO） production in treated cells. Moreover, this was blocked by concurrent treatment with the NO synthase inhibitor NC-methyl-L-arginine （L-NMMA）, which suppressed MC-LR- induced mutations as well. The survival of mitochondrial DNA-depleted （pO） AL ceils was markedly decreased by MC-LR treatment compared to that in AL cells, while the CD59 mutant fraction was unaltered. These results provided clear evidence that the genotoxicity associated with chronic MC-LR exposure in mammalian cells was mediated by NO and might be considered as a basis for the development of therapeutics that prevent carcinogenesis.
