水化电子e_(aq)~-对乙酰甲胺磷的作用

利用60Co-γ辐射降解有机磷农药乙酰甲胺磷的稀水溶液,以乙酰胆碱酯酶抑制率为指标,研究了不同吸收剂量下水化电子对乙酰甲胺磷稀水溶液辐照前后的毒性变化;并采用高效液相色谱、离子色谱、气-质联用等检测手段对降解产物进行了分析.结合溶液毒性变化和降解率、生成的无机离子浓度、降解产物结构分析等,初步推导了60Co-γ辐射降解过程中水化电子对乙酰甲胺磷的作用机理.     

新烟碱类杀虫剂吡虫啉和啶虫脒对人神经母细胞瘤SK-N-SH细胞的毒性作用

吡虫啉和啶虫脒是目前使用较广的2种新烟碱类杀虫剂,它们在环境、食品和人体样品中的普遍残留,对人体健康构成威胁,但目前关于其对人的神经毒性仍知之甚少.本文以人神经母细胞瘤SK-N-SH细胞为模型,采用体外细胞实验,研究不同浓度吡虫啉和啶虫脒暴露对细胞活力、细胞形态、烟碱型乙酰胆碱受体(nAChRs)α7亚基的mRNA和蛋白表达、乙酰胆碱酯酶活性以及氧化应激的影响,为这2种杀虫剂的健康风险评价提供依据.实验中,先将SK-N-SH细胞分别暴露于不同浓度的吡虫啉和啶虫脒24 h,通过测定细胞活力,确定2种杀虫剂的10％抑制浓度(IC10)值.在此基础上,设定3个梯度的低暴露浓度(0.01、0.1和1 mmol· L-1)和溶剂对照,研究吡虫啉和啶虫脒对SK-N-SH细胞其他指标的影响(暴露24 h后).细胞活力、氧化损伤和乙酰胆碱酯酶活性分别用相应的试剂盒测定,细胞形态用倒置光学显微镜观察,nAChRs α7亚基的mRNA和蛋白表达分别用RT-qPCR和Western Blot测定.结果 表明,吡虫啉和啶虫脒的IC10值分别约为1.5 mmol· L-1和2.0 mmol· L-1.1 mmo1·L-1吡虫啉对nAChR α7的mRNA表达和蛋白表达均显著提高,对乙酰胆碱酯酶活性有显著抑制,并引起细胞显著的氧化应激(P＜0.05).0.1 mmol· L-1吡虫啉对乙酰胆碱酯酶活性有显著抑制(P＜0.05).1 mmol· L-1啶虫脒对nAChR α7的mRNA表达和蛋白表达均有显著提高(P＜0.05).为进一步揭示吡虫啉的影响,对0.1 mmol· L-1吡虫啉暴露组和溶剂对照组细胞进行了转录组分析,发现吡虫啉暴露对一些神经退行性疾病相关基因及其他一些重要通路相关基因有显著影响.本研究证明,吡虫啉和啶虫脒在非致死浓度条件下会对细胞产生一系列显著影响,吡虫啉的影响大于啶虫脒.     

苹果和土壤中甲基硫菌灵及其代谢物残留消解动态

研究了甲基硫菌灵及其代谢物多菌灵在苹果和土壤中的消解动态和最终残留。苹果和土壤中甲基硫菌灵及多菌灵采用乙酸乙酯提取,提取液经旋转蒸发仪浓缩后经SPE氨基净化柱净化,过0.22μm滤膜后上机,采用超高效液相色谱和272 nm紫外检测器检测,外标法定量。添加浓度为0.05、1.0、5.0 mg·kg-1时,苹果中甲基硫菌灵的添加回收率在76.3%~108.5%之间,相对标准偏差为1.7%~5.7%;土壤中甲基硫菌灵的添加回收率在90.0%~106.7%之间,相对标准偏差为2.6%~7.4%;苹果中多菌灵的添加回收率在82.7%~109.3%之间,相对标准偏差为8.6%~11.5%;土壤中多菌灵的添加回收率在77.9%~116.9%之间,相对标准偏差为4.8%~7.3%;检测方法满足农药留分析要求。在山东省泰安市、安徽省宿州市、河北省保定市3个试验点两年的消解动态试验结果表明:施药后,甲基硫菌灵在苹果和土壤中均很快转化为多菌灵。甲基硫菌灵在苹果和土壤中的半衰期均小于6.3 d,属于易降解农药。两年三地的最终残留试验结果表明,甲基硫菌灵及代谢物多菌灵在苹果和土壤中最终残留量均低于0.05 mg·kg-1,小于我国规定的最大残留限量(MRL)3.0 mg·kg-1和欧盟规定的MRL 0.5 mg·kg-1。说明按照推荐的甲基硫菌灵在苹果上的施用方法:施用药量(有效成分)500 mg·kg-1,施药2次,施药间隔7 d,采收间隔期大于21 d,在以上条件下施药是安全的。     

辛硫磷和敌百虫协同抑制斑马鱼乙酰胆碱酯酶(AChE)活性

以辛硫磷和敌百虫为供试毒物,研究其对斑马鱼的单一和联合毒性效应。结果显示,辛硫磷和敌百虫对斑马鱼的96 h半致死浓度(96 h-LC_(50))值分别为6.482 mg·L~(-1)和27.877 mg·L~(-1);按照农药毒性分级标准,辛硫磷对斑马鱼是高毒,敌百虫对斑马鱼是中毒。在辛硫磷和敌百虫联合急性毒性实验中,24、48、72和96 h的相加指数均大于0,表明辛硫磷和敌百虫对斑马鱼的联合毒性为协同效应。采用生化法测定乙酰胆碱酯酶活性发现,乙酰胆碱酯酶活性与辛硫磷、敌百虫以及辛硫磷+敌百虫之间有显著的剂量-效应关系,而且联合作用毒性均大于单一作用毒性。     

磷酸三苯酯对斑马鱼早期生命阶段的神经毒性研究

磷酸三苯酯(triphenyl phosphate,TPP)作为多溴联苯醚类阻燃剂的替代产品,是一类生产和需求量均相当高的有机磷酸酯类阻燃剂,目前已在多种环境介质以及生物体内均有不同程度检出。由于结构和有机磷农药具有相似性,其对生物的神经毒性值得关注。本研究以斑马鱼为实验动物,研究了TPP(5~625%g·L-1)的胚胎发育毒性和行为毒性,并通过检测乙酰胆碱酯酶活性以及神经系统相关基因的转录水平,探讨其可能的毒性机制。研究发现,TPP可导致斑马鱼胚胎孵化时间延长,体长变短,心率变慢。同时,TPP暴露也可以影响斑马鱼幼鱼在持续光照和明暗周期刺激下的游泳行为,表现为低浓度增加而高浓度降低其游泳速度。而TPP暴露后幼鱼乙酰胆碱酯酶活性以及神经发育相关基因转录水平的变化可能是导致其行为毒性的原因。虽然实验中所设定的暴露浓度高于环境中一般浓度,但TPP在短期暴露中所表现出的胚胎和神经发育毒性表明TPP对于水生生物可能存在一定风险,需要进一步研究加以确认。     

4种农药复合污染对斑马鱼仔鱼联合毒性效应

为探明农药混合污染对斑马鱼的联合毒性效应,以斑马鱼仔鱼为研究对象,开展了氯氰菊酯、咪鲜胺、马拉硫磷和杀螟硫磷等4种农药的联合毒性效应研究。研究表明,氯氰菊酯、马拉硫磷,杀螟硫磷和咪鲜胺对斑马鱼仔鱼的96 h-LC_(50)值分别为0.12、17.88、12.39和1.45 mg·L~(-1)。根据96 h-LC_(50)值采用等毒比(1∶1)进行二元及多元联合毒性试验。二元农药混合污染(氯氰菊酯+马拉硫磷、氯氰菊酯+杀螟硫磷、氯氰菊酯+咪鲜胺和杀螟硫磷+咪鲜胺)对斑马鱼仔鱼联合作用表现协同作用。马拉硫磷+杀螟硫磷对斑马鱼仔鱼联合毒性在24 h时表现为协同作用,在其他不同时间均表现为相加作用。马拉硫磷+咪鲜胺二元农药对斑马鱼仔鱼联合毒性表现为拮抗作用。氯氰菊酯、咪鲜胺、马拉硫磷和杀螟硫磷4种农药的所有三元和四元混合污染对仔鱼联合毒性作用均表现为协同作用。研究表明,在真实的环境中,农药以混合物形式存在可能增加其对水生生物的毒性效应,给生态环境造成严重影响。     

12种杀菌剂制剂对半闭弯尾姬蜂的急性毒性及安全性评价

采用试管药膜法测定了12种杀菌剂制剂对半闭弯尾姬蜂成蜂的急性接触毒性,结合安全性系数评价了供试药剂对半闭弯尾姬蜂的安全性。急性毒性测定结果表明,氟硅唑和啶菌噁唑对半闭弯尾姬蜂成蜂的接触毒性最高,LC50值分别为220.022和223.115 mg·L-1;其次为多抗霉素、丙森锌和戊唑醇,LC50值分别为436.496、472.358和638.638 mg·L-1;其余7种杀菌剂制剂嘧霉胺、啶酰菌胺、苯醚甲环唑、多菌灵、嘧菌酯、嘧菌环胺和异菌脲对半闭弯尾姬蜂成蜂的触杀毒性都较低,LC50值均大于1 000 mg·L-1。安全性评价结果表明,丙森锌和啶菌噁唑对半闭弯尾姬蜂成蜂具有高风险性,安全系数分别为0.16和0.42;嘧霉胺、多抗霉素、氟硅唑和戊唑醇为中等风险性,安全系数分别为1.43、1.56、2.20和3.23;其余6种杀菌剂制剂啶酰菌胺、苯醚甲环唑、多菌灵、嘧菌酯、嘧菌环胺和异菌脲对半闭弯尾姬蜂表现为低风险性,安全系数均大于5。结果显示:甾醇脱甲基抑制剂氟硅唑、戊唑醇和啶菌噁唑以及苯胺基嘧啶类杀菌剂嘧霉胺、有机硫杀菌剂丙森锌和抗菌素多抗霉素对半闭弯尾姬蜂成蜂具有急性毒性风险,在有害生物综合治理中应谨慎使用,特别是啶菌噁唑和丙森锌,以免对半闭弯尾姬蜂造成不良影响和危害。     

Methylobacterium sp. YAL-2对乙酰甲胺磷的降解特性

从有机磷生产厂家的下水道污泥中分离出一株对高浓度和低浓度乙酰甲胺磷都具有高效降解能力的寡营养菌YAL-2,根据形态、生理生化和16S rRNA基因系统发育分析,将菌株YAL-2鉴定为Methylobacterium sp.降解特性实验表明,菌株YAL-2能利用乙酰甲胺磷为唯一碳源生长和降解;在添加了甲醇的无机盐培养基中,84 h可完全降解300mg L-1乙酰甲胺磷,24 h将50 mg L-1和10 mg L-1乙酰甲胺磷降至非检测水平;4 d能完全去除100 mg L-1甲胺磷,5 d分别降解58.4%和40.6%的100 mg L-1乐果、敌敌畏.小青菜农药残留去除实验显示,菌株YAL-2可在7 d内将乙酰甲胺磷和甲胺磷将至限量水平.结果表明,将菌株YAL-2应用于保证果蔬等食品的食用安全是可行的.     

典型重金属胁迫对日本沼虾的氧化损伤及交互作用

为深入探讨水体不同浓度重金属联合对水生生物的慢性毒性机制,本研究以日本沼虾(Macrobranchium nipponense)为受试生物,镉(Cd)和铅(Pb)为目标金属,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、金属硫蛋白(MT)和丙二醛(MDA)为测试终点,研究不同浓度的Cd和Pb单一及联合暴露对日本沼虾的氧化损伤及交互作用。实验结果表明:Cd对虾的致死浓度为1 mg·L-1,当其与同浓度Pb联合时,致死毒性增强;在0.01 mg·L-1和0.1 mg·L-1下联合时均表现为拮抗作用。不同处理组对标志物产生不同程度的诱导或抑制效应,其中,SOD活性均受到胁迫抑制,0.1 mg·L-1Cd暴露10 d后对肝胰腺SOD抑制率达53.38%,0.1 mg·L-1Pb暴露10 d后对肌肉SOD抑制率达70.02%;CAT活性整体受胁迫激活,肝胰腺与肌肉CAT活性在时间尺度上呈现相反的变化规律;肝胰腺中MT和MDA对重金属的敏感性要高于肌肉;综合生物标志物响应(IBR)评价表明,机体在时间尺度上可通过酶活性调节而具有一定的解毒功能,但并不能消除重金属引起的氧化损伤,且重金属单一毒性要高于联合毒性,其中Cd对肝胰腺毒性最大,Pb对肌肉毒性最大。研究结果能够为水体重金属生态风险预警、水质基准制定及流域水环境管理提供依据。     

花翅摇蚊乙酰胆碱酯酶的底物专一性及对胆碱酯酶抑制剂敏感度的比较

摇蚊是重要的水生昆虫,可用于水环境质量的生物学评价.本研究以花翅摇蚊(Chironomus kiinensis)为材料,研究了花翅摇蚊乙酰胆碱酯酶(Acetylcholinesterase, AChE)的底物专一性及其对胆碱酯酶抑制剂的敏感度.结果表明,花翅摇蚊AChE对乙酰硫代胆碱(ATCh)的水解活性最高,其次是β-甲基硫代乙酰胆碱(β-MTCh)、丙酰硫代胆碱(PrTCh)和丁酰硫代胆碱(BuTCh);氨基甲酸酯药剂对花翅摇蚊AChE的抑制能力高于有机磷类,其中克百威对摇蚊AChE的抑制能力最强, I50值为1×10-8 mol L-1.有机磷和氨基甲酸酯类抑制剂对摇蚊AChE的抑制趋势基本一致,均随着抑制时间延长,抑制率不断增加.由此可得出,花翅摇蚊AChE的最适底物是ATCh;离体条件下,摇蚊AChE对低浓度的有机磷和氨基甲酸酯药剂比较敏感.     

Acute toxicity evaluation of triazophos,deltamethrin and their combination on earthworm,Eudrilus eugeniae and its impact on AChE activity

The acute toxicity of three formula grade pesticides namely, triazophos (an organophosphate, OP), deltamethrin (a pyrethroid) and combined pesticide (triazophos?+?deltamethrin) was determined in earthworm, Eudrilus eugeniae. They were exposed to different concentrations of these pesticides for 48 h by paper contact toxicity method. The LC₅₀ values for triazophos, deltamethrin and of combination were determined as 0.076, 0.031 and 0.065?μg/cm², respectively. To study the sublethal effect of these pesticides, E. eugeniae were exposed to 5% and 10% of LC₅₀ of pesticides for 48 h. Morphological alterations such as coiling, clitellar swelling, mucus release and bleeding followed by body segmentation were observed in exposed earthworm. Acetylcholinesterase (AChE) activity assayed in different regions of body segment exhibited a significant (p?<?0.05) decrease in its activity particularly in the pre-clitellar region as compared to other regions. The altered behavioural responses in pesticides exposed earthworms would have been due to decline in AChE activity of the nervous system.     

Organophosphate Residues in Grasshoppers from Sprayed Rangelands

Grasshoppers (Orthoptera) were collected in pastures that had been sprayed with malathion and acephate to estimate the secondary exposure of insectivorous birds to those pesticides. Residues of malathion were below 3 ppm at 30 and 54 hours after spraying and no malaoxon was detected. In contrast, acephate was found at 8 and 9 ppm 4 hours after spray; 3-5 ppm of the toxic metabolite methamidophos were also detected at that time. By 53 hours postspray, acephate levels declined to 2 ppm and methamidophos to less than 1 ppm. These results suggest that although malathion may not be a hazard to insectivorous species, acephate may be hazardous through metabolic transformation to methamidophos.     

Sublethal pesticide concentrations and predation jointly shape life history: behavioral and physiological mechanisms.

Despite their relevance for risk assessment, the interactive effects of pesticide and predation cues are poorly understood because the underlying behavioral and physiological mechanisms are largely unknown. To explore these mechanisms, we reared larvae of the damselfly Coenagrion puella at three different predation risk levels and a range of environmentally realistic concentrations of three pesticides used worldwide (atrazine, carbaryl, and endosulfan). We compared key development responses (growth rate, developmental time, and final size) against food ingestion, assimilation, and conversion efficiency, and acetylcholinesterase (AChE) activity. Predation risk impaired all endpoints, including AChE activity, while the effects of pesticide stress were smaller for atrazine and endosulfan and absent for carbaryl. The effects of both stressors and their interaction on life history were mostly indirect through resource acquisition and energy allocation. Compensatory physiological mechanisms to pesticide stress (atrazine and endosulfan) were present in larvae reared in the absence of predation stress but were offset under predation stress. As a result, smaller size (atrazine and endosulfan) and lower growth rate (endosulfan) from pesticide stress were only found in the highest predation risk treatment. Our results provide insight as to the conditions under which interactions between stressors are likely to occur: damselfly populations at high density and living in fish ponds will be more affected by pesticides than populations at low densities in fishless ponds. By identifying variables that may shape the interaction between predation stress and other stressors such as pesticides, our mechanistic approach may help to bridge the gap between laboratory and field studies.     

BDE-47和BDE-209对乙酰胆碱酯酶(AChE)活性的抑制特性及分子作用力研究

多溴联苯醚(PBDEs)是应用广泛的溴代阻燃剂,其中2,2',4,4'-四溴联苯醚(BDE-47)和2,2',3,3',4,4',5,5',6,6'-十溴联苯醚(BDE-209)广泛存在于环境中。PBDEs具有神经毒性,但其致毒机制尚不明确。本文通过研究BDE-47与BDE-209对乙酰胆碱酯酶(AChE)活性的影响及二者与AChE相互作用的光谱分析,揭示BDE-47与BDE-209导致神经毒性的致毒机制。BDE-47和BDE-209在一定浓度范围内均能够抑制AChE分解乙酰胆碱;随着浓度的增加,两者的抑制率均呈现出先增加后降低的规律。BDE-47浓度为400μmol·L-1时抑制率达到最大,为22.3%;BDE-209浓度为200μmol·L-1时抑制率达到最大,为11.2%。相同浓度下,BDE-47对AChE的抑制率始终大于BDE-209,表明AChE对BDE-47更加敏感。荧光光谱分析结果表明BDE-47和BDE-209与AChE之间的相互作用均主要为疏水作用,同时不存在范德华引力作用;BDE-47与AChE的结合常数大于BDE-209与AChE的结合常数,表明BDE-47更易与AChE相互作用。此外,温度的升高不利于BDE-47和BDE-209与AChE之间相互作用。BDE-47和BDE-209抑制AChE活性很可能是导致神经毒性通路之一。     

氧化型染发剂对沙蚕的毒性效应及对部分酶活性的影响

在实验室模拟条件下,研究了氧化型染发剂对双齿围沙蚕(Perinereis aibuhiteusis Grube)的急性毒性效应及不同暴露浓度(0、40、80、160、320mg·L-1)和暴露时间(0、4、6、8、10d)下对其体内乙酰胆碱酯酶(AChE)和超氧化物歧化酶(SOD)活性的影响.结果表明,1)暴露3d后氧化型染发剂对沙蚕的半数致死浓度(LC50)为1849.6mg·L-1;2)沙蚕体内AChE和SOD活性受到氧化型染发剂暴露浓度的显著影响:暴露3d后,随暴露浓度的升高(0～320mg·L-1),AChE和SOD活性均呈先被诱导后逐渐下降的变化趋势;3)沙蚕体内AChE和SOD活性也受到暴露时间的显著影响:40mg·L-1浓度下,随暴露时间的延长(0～10d),SOD活性呈先下降又缓慢上升的趋势,而AChE活性变化没有显著规律;4)通过比较发现,相对于AChE,SOD的活性变化更能反映氧化型染发剂对沙蚕的毒性作用.     

Nerve conduction studies in sprayers occupationally exposed to mixture of pesticides in a mango plantation at Lucknow,North India

In this study, nerve conduction, organochlorine (OC) pesticide residues in blood and cholinesterase activity levels of pesticide sprayers employed in mango plantations at Lucknow, North India, were determined. Fifty-two sprayers from mango plantations who regularly spray mixture of pesticides like organophosphates (OP), OCs, and carbamates were considered as exposed group. Eighteen subjects with similar socio-economic status of exposed group, who do not handle pesticides, were selected as controls. Questionnaire-based interviews related to personal and occupational histories of the study subjects were carried out. Sprayers did not use any personal protective equipment during pesticide handling. The blood-pesticide analyses of sprayers show higher mean values of hexachlorohexane (HCH), γ-HCH, δ-HCH, total HCH, op-DDT compared with the controls. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activites were significantly reduced among sprayers. Risk of motor nerve conduction deficits was observed in sprayers with low AChE activity. Negative correlation of motor and sensory nerve conduction deficits was observed with the duration of exposure and age among sprayers. The study demonstrated that the prolonged exposure to mixture of pesticides, ergonomic factors, decline in cholinesterase activity may lead to nerve conduction dysfunction. The findings suggest the need for controlled use of pesticides in the plantation and indicated the need for training and implementation of hygiene practices like proper usage of personal protective equipments.     

Carbofuran-induced effects on acetylcholinesterase (AChE) in erythrocytes and liver of Cyprinus carpio

A study was conducted to determine the effects of long-term exposure to carbofuran on erythrocyte and liver acetylcholinesterase (AChE) activity in Cyprinus carpio, and assess which tissue was more sensitive to pesticide exposure examining this enzyme. Fish were allowed to accilimatize in toxicant-free water for 24 days after 60-day exposure. AChE activity was determined with a spectrophotometer using acetylthiocholine iodide as a substrate in erythrocytes and liver. Enzymic activity of erythrocytes and liver decreased over time. A higher degree of enzyme inhibition was observed in erythrocyte compared to liver. The degree of enzyme inhibition was positively correlated with exposure time. When exposed fish were transferred to clean water, recovery was greater in erythrocytes than liver. Erythrocyte AChE activity recovered after 18 days, while it required 21 days in liver. The findings of this study indicate that erythrocyte AChE is more sensitive to carbofuran than liver. The greater sensitivity of erythrocyte AChE suggests that it may be more useful as a biomarker for monitoring status of pollution in freshwater bodies.     

Determination of pesticides in apples,grapes and apple juice from a Kosovo market by gradient liquid chromatography with tandem mass spectrometry

Apple, grape, and apple juice were analyzed for pesticides using a multireaction mode (MRM) method in samples taken from a Kosovo market. With this method it was possible to analyze about 100 pesticides in the ESI mode. In these samples some types of pesticides were found, but most of them did not exceed the maximum tolerance levels. In apple samples, six pesticides were detected but only three of them were in sufficient quantitites. Dimethoat was below the limit, while acephate and imazalil exceeded the limit. In grape and apple juice samples, all of pesticides which were found did not exceed the maximum tolerable limits.     

3种有机磷农药对水生生物的乙酰胆碱酯酶抑制效应的物种敏感度分析初探

通过筛选敌敌畏、马拉硫磷和对硫磷3种有机磷农药对水生生物的急性毒性数据和乙酰胆碱酯酶抑制效应数据,构建物种敏感度分布曲线进行了比较分析。结果表明,敌敌畏对水生生物的急性毒性和乙酰胆碱酯酶抑制效应的大小顺序为:酶体内抑制效应酶体外抑制效应急性毒性;马拉硫磷和对硫磷的乙酰胆碱酯酶抑制效应数据不足但趋势相似,顺序为:酶体内抑制效应急性毒性酶体外抑制效应。敌敌畏的急性毒性和酶体外抑制效应的5%危害浓度(HC5)分别为2.07μg·L~(-1)和1.53μg·L~(-1),两者相差1.4倍。在水质基准推导中,乙酰胆碱酯酶抑制效应数据对有机磷农药的水生生物基准具有重要的参考价值。