拟除虫菊酯类农药的免疫毒性研究进展

拟除虫菊酯类杀虫剂因其高效、对哺乳动物低毒和易降解等特性已被广泛使用,目前对其生态毒理学的研究主要集中在神经及内分泌干扰、发育和生殖毒性方面,而关于其免疫毒性的研究也越来越受到了关注。文章对拟除虫菊酯类农药的免疫毒性及其分子机制研究进展进行了总结,主要从免疫器官、免疫细胞、免疫分子和免疫功能等方面综述了此类杀虫剂对不同生物的免疫毒性及其可能的分子机制,同时总结了拟除虫菊酯类杀虫剂暴露与免疫相关疾病发生的关联,以期为拟除虫菊酯类农药免疫毒性的进一步探究提供参考。     

QuEChERS-气相色谱-质谱联用法测定香蕉中苯醚甲环唑残留量的测量不确定度评定

三唑类杀菌剂因具有高效、广谱及持效期长的特点而被广泛应用于农作物病害防治。大量研究表明,随着三唑类杀菌剂的长期、广泛施用,大量未被有效利用的残留药剂进入土壤或滞留在植株上,最终通过雨水冲刷或地表径流进入水体,危害水生生物的安全。本文综述了三唑类杀菌剂在水环境中的残留现状,并从急性毒性、氧化应激毒性、发育毒性、遗传毒性、内分泌干扰效应、对机体代谢的影响及联合作用毒性等多个方面、多层次概述了该类杀菌剂暴露对鱼类、两栖类、溞类和藻类等水生生物的毒性效应研究进展,并展望了该类杀菌剂的未来研究重点和发展方向,旨在为三唑类杀菌剂的合理应用和有效管理提供参考,为减少三唑类杀菌剂对水生生态系统的影响提供理论依据。

     

有机磷类杀虫剂代谢机制研究进展

文章对有机磷类杀虫剂代谢机制的研究进展以及昆虫对此类杀虫剂的相关代谢抗性机制进行了总结,阐述了有机磷杀虫剂的生物代谢途径及相关代谢酶系。在生物体中,有机磷类杀虫剂主要发生氧化代谢、水解代谢和轭合代谢等反应。其氧化代谢主要在细胞色素P450酶系(P450s)的催化作用下进行,其中,最重要的氧化反应是硫代有机磷酸酯类杀虫剂氧化脱硫形成生物毒性更高的有机磷氧化物的反应,以及氧化脱芳(烷)基化的反应;有机磷杀虫剂及其氧化产物在生物体内还可发生水解代谢反应,在对氧磷酶PON1等磷酸三酯酶的催化作用下,水解生成低毒性或者无毒的代谢物;有机磷杀虫剂的轭合代谢主要是在谷胱甘肽硫转移酶(GSTs)的催化下进行的。昆虫对有机磷类杀虫剂的代谢抗性与昆虫中参与此类杀虫剂代谢的解毒酶的改变密切相关,其中,与有机磷类杀虫剂代谢相关的P450s基因的过量表达和酶活性增强、丝氨酸水解酯酶的过量表达及基因突变、GSTs基因的过量表达等,均可导致铜绿蝇Lucilia cuprina、桃蚜Myzus persicae等昆虫对二嗪磷和马拉硫磷等有机磷类杀虫剂的代谢抗性。明确有机磷类杀虫剂的结构特点、代谢途径以及昆虫对此类杀虫剂的代谢抗性机制,对掌握有机磷类杀虫剂的毒理学机制,安全有效地使用此类杀虫剂,有效治理害虫对有机磷类杀虫剂的抗药性,以及开发生物选择性好的新型有机磷类杀虫剂,均具有重要意义。     

农药对蚯蚓的毒理学效应研究进展

农药在使用过程中会通过液滴飞溅漂移、包装残留、加工泄露以及生物体排泄等多种方式不可避免地进入土壤环境，给土壤生物带来潜在的环境风险。蚯蚓是土壤中主要的生物类群，也是评估农药毒性风险最合适的土壤模式生物。本文基于当前国内外关于农药对蚯蚓毒理学效应影响的研究，概括了农药进入土壤中的途径及其在土壤中的残留现状、农药在蚯蚓体内的富集与消除行为；归纳了农药暴露对蚯蚓产生的生长及生殖毒性、细胞毒性、神经毒性、遗传毒性和氧化应激等毒性影响，着重综述了转录组学、代谢组学及微生物组学等组学方法在揭示农药对蚯蚓毒性作用机制方面的最新研究应用进展。本文可为农药的土壤生态风险评估提供必要的数据支撑，并为农药土壤污染风险管控和修复提供科学依据。     

甲草胺对非靶标生物的毒理学研究进展

甲草胺是一种选择性芽前除草剂,在20世纪末期被广泛应用于防治大豆、花生、水稻田等一年生禾本科及阔叶杂草.目前,甲草胺由于其致畸性及内分泌干扰活性已被多国禁用.文章综述了甲草胺进入环境后对非靶标生物的毒理学研究进展,主要包括急性毒性、慢性毒性和氧化应激效应等,旨在为甲草胺生态环境风险评估提供数据资料.     

拟除虫菊酯类农药对哺乳动物神经毒理的研究进展

对拟除虫菊酯类(SPs)农药对哺乳动物的神经毒理学研究过程及其最新进展进行了综述。拟除虫菊酯类农药是目前使用广泛的一类神经毒性杀虫剂,主要用于农业和卫生害虫的防治。已有研究结果显示拟除虫菊酯类农药对非靶标野生动物和人类的神经系统有一定的毒性作用,其对哺乳动物的神经毒性主要表现为急性和慢性神经毒性,而且其毒性作用与拟除虫菊酯类农药的立体结构相关,有一定的对映体选择性差异。     

三唑磷对麦穗鱼脑组织中乙酰胆碱酯酶的诱导

为了检测有机磷杀虫剂对鱼脑组织中乙酰胆碱酯酶(AChE, EC 3.1.1.7)的诱导,采用间接非竞争酶联免疫吸附测定法(ELISA)检测了三唑磷胁迫下麦穗鱼Pseudorasbora parva脑组织中乙酰胆碱酯酶含量的变化。当暴露浓度仅为0.1 μg /L时,三唑磷即对AChE产生诱导。由于存在诱导效应,三唑磷对酶活性的抑制在一定程度上被酶蛋白含量的提高所掩盖。研究结果表明,以酶蛋白替代总蛋白来衡量粗酶液中AChE的活性,可以明显提高对有机磷胁迫作用的检测灵敏度。     

手性农药选择性生物活性与毒性效应研究进展

手性农药因对映体在生物活性、毒性、环境行为等方面的差异性而备受关注,充分了解对映体的立体选择性对开发高活性农药及减量使用具有重要意义。本文聚焦手性农药对映体的立体选择性效应,系统地调研了对映体生物活性和毒性选择性差异,并进行了分类梳理,重点综述了手性农药对映体的生物活性及毒性和环境风险的差异性,阐述了手性农药对非靶标生物造成的氧化应激、内分泌干扰等慢性毒性,同时关注选择性的规律与机制,为环境友好型高效手性农药的开发、手性农药的风险评估及管理、手性农药对映体立体选择性机制研究提供参考。     

农药助剂烷基酚及其醚的限用或禁用

烷基酚及其醚是一种重要的农用表面活性剂,广泛应用于农药助剂加工,并伴随着农药的使用释放到环境中。它是一种典型的环境激素,具有内分泌干扰效应、生殖和发育等多种毒性效应,在环境中难降解。大量无序的施用于农田,不仅威胁到环境生态安全,而且会影响到农产品质量安全、农业从业人员的职业安全及国际贸易安全。建议限制该类物质在农药助剂领域的使用。     

禾草灵的作用机制及环境生态效应研究进展

禾草灵 (diclofop-methyl)属芳氧苯氧丙酸类除草剂,广泛应用于禾本科杂草防除,其降解受到土壤有机质含量、pH值、氧气等众多因素的影响。母体化合物禾草灵及其主要降解产物禾草灵酸都具有除草活性,并会对环境中的一些非靶标生物产生急性或慢性毒性,是一类环境内分泌干扰物及过氧化物酶体增殖剂;同时,由于部分杂草产生抗性,进而演替成优势种群,迫使禾草灵的用量增加,更加重了其环境压力。文章就禾草灵的作用机制,其在环境中的降解、吸附等行为以及对非靶标生物的生态效应进行了综述,探讨了其中存在的一些问题,如生态毒理尤其是对映体差异性在毒性方面数据的缺乏等,并对今后的发展方向进行了展望。     

A review on the mechanisms involved in hyperglycemia induced by organophosphorus pesticides

Organophosphorus (OP) compounds are cholinesterase-inhibiting chemicals used as pesticide. Exposures to OPs cause a significant number of poisonings and deaths each year. One of the reported adverse effects in human exposure to OPs is hyperglycemia. Animal studies have also shown altered glucose homeostasis following acute or chronic exposures to OPs. The objective of this paper is to provide a brief review of the mechanisms involved in the OP-induced glucose homeostasis alteration. To reach this objective, a search of the literature using Medline/Index Medicus, Scopus, and Chemical Abstract were performed, most of relevant citations were studied and summarized. To better understand the nature of glucose homeostasis, the principles of glucose production, metabolism, and its hormonal control have been discussed. Collection of theses studies support the conclusion that hyperglycemia is the outcome of acute or chronic exposure to OPs. OPs can influence body glucose homeostasis by several mechanisms including physiological stress, oxidative stress, inhibition of paraoxonase, nitrosative stress, pancreatitis, inhibition of cholinesterase, stimulation of adrenal gland, and disturbance in metabolism of liver tryptophan.     

Mutagenic, genotoxic and enzyme inhibitory effects of carbosulfan in rainbow trout Oncorhynchus mykiss

Rainbow trout (Oncorhynchus mykiss; 116.88 ± 21.69 g) were exposed to sublethal concentrations (25 μg/L) of carbosulfan for 60 days to test if the long term exposure of fish to carbosulfan affects red blood cells acetylcholinesterase (AChE), δ-aminolevulinic acid dehydratase (ALA-D) and paraoxonase (PON) enzyme activity and induces genotoxic and/or mutagenic effects. The exposure resulted in inhibition of AChE and ALA-D activity of rainbow trout when compared to control fish. The activity of PON was not affected by carbosulfan. Interestingly, carbosulfan was found to induce DNA damage in red blood cells (comet assay) and proved to be mutagenic as revealed by the Ames test. Results indicate that blood AChE and ALA-D of rainbow trout may be a sensitive biomarker for assessment of carbosulfan contaminated water bodies. Furthermore, because the Ames test and comet assay were proven successful to detect the genotoxicity of carbosulfan, we proposed that nonlethal techniques such as blood collection from caudal vein of fish should be used to determine potential toxic effects of other pesticides to surrounding environment.     

Monocrotophos induced lipid peroxidation and oxidative DNA damage in rat tissues

Monocrotophos (dimethyl(E)-1-methyl-2-(methyl carbamoyl) vinyl phosphate, MCP), a substituted vinyl phosphate, is a potent systemic toxicant and used for control of variety of pests. The present study is undertaken to evaluate the genotoxic potential of monocrotophos and time-dependent repair of the damaged DNA in rats, using single cell gel electrophoresis or comet assay. The involvement of oxidative stress was also examined by estimation of thiobarbituric acid reactive substances (TBARS) in the tissues of MCP exposed rats. The rats were given oral exposure of 4.5 and 9 mg MCP/kg body weight once as well as 0.3 and 0.6 mg MCP/kg body weight for 60 days. A dose-dependent increase was recorded in the levels of TBARS in the liver, kidney, spleen and brain of MCP exposed rats. Cytotoxicity of MCP is evident from the histopathological studies of rat tissues. The level of DNA damage was estimated by scoring 50 cells per animal, dividing into five types, Types 0, I, II, III and IV. The results clearly indicated that exposure to MCP, acutely or chronically, caused a dose-dependent increase in the number of damaged nuclei of Types II, III and IV in the liver, kidney, spleen and brain of rats. When the DNA damage was studied 48 and 72 h post MCP treatment, a significant reduction in the number of types III and IV nuclei was observed in all the tissues indicating a time-dependent repair. From the present study, it can be concluded that oxidative stress may be involved in the toxicity of MCP and MCP induces DNA damage in all the rat tissues exhibiting genotoxic potential in vivo.     

Comet assay in gill cells of Prochilodus lineatus exposed in vivo to cypermethrin

Agricultural chemicals can induce genetic alterations on aquatic organisms that have been associated with effects on growth, reproduction and population dynamics. The evaluation of DNA damage in fish using the comet assay (CA) frequently involves the utilization of erythrocytes. However, epithelial gill cells (EGC) can be more sensitive, as they are constantly dividing and in direct contact with potentially stressing compounds from the aquatic environment. The aim of the present study was to evaluate (1) the sensitivity and suitability of epithelial gill cells of Prochilodus lineatus in response to different genotoxic agents through the application of the CA, (2) the induction of DNA damage in this cell population after in vivo exposure to cypermethrin. Baseline value of the CA damage index (DI) for EGC of juvenile P. lineatus was 144.68 ± 5.69. Damage increased in a dose-dependent manner after in vitro exposure of EGC to methyl methanesulfonate (MMS) and H₂O₂, two known genotoxic agents. In vivo exposure of fish to cypermethrin induced a significant increase in DNA DI of EGC at 0.150 μg/l (DI: 239.62 ± 6.21) and 0.300 μg/l (270.63 ± 2.09) compared to control (150.25 ± 4.38) but no effect was observed at 0.075 μg/l (168.50 ± 10.77). This study shows that EGC of this species are sensitive for the application of the CA, demonstrating DNA damage in response to alkylation (MMS), oxidative damage (H₂O₂), and to the insecticide cypermethryn. These data, together with our previous study on DNA damage induction on erythrocytes of this species, provides useful information for future work involving biomonitoring in regions where P. lineatus is naturally exposed to pesticides and other genotoxic agents.     

Allelochemical ethyl 2-methyl acetoacetate (EMA) induces oxidative damage and antioxidant responses in Phaeodactylum tricornutum

Ethyl 2-methyl acetoacetate (EMA) is a novel allelochemical exhibiting inhibitory effects on the growth of marine unicellular alga Phaeodactylum tricornutum (P. tricornutum). Oxidative damage and antioxidant responses in P. tricornutum were investigated to elucidate the mechanism involved in EMA inhibition on algal growth. The increase in reactive oxygen species (ROS) levels and malondialdehyde (MDA) contents following exposure to EMA suggested that alga was suffered from oxidative stress and severely damaged. The decrease in cell activity and cellular inclusions suggested that cell growth was greatly inhibited. The activities of the antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxide (GSH-PX) and glutathione S-transferase (GST) increased with the exposure concentration and decreased with the prolongation of exposure time. Cellular ascorbic acid (AsA) and reduced glutathione (GSH) systems were also involved in resisting oxidative stress of EMA by altering the composition of AsA and GSH pools. EMA exposure increased the contents of AsA, GSH, dehydroascorbate (DAsA) and glutathione (GSSG). However, the regeneration rate of AsA/DAsA did not change obviously between treatments and the control, while that of GSH/GSSG decreased significantly under 14 mmol/L EMA exposure on the 3rd day. These results showed that EMA-induced oxidative damage might be responsible for EMA inhibition on P. tricornutum growth and cellular antioxidant enzymes and non-enzymatic antioxidants were improved to counteract the oxidative stress.     

The impact of simultaneous intoxication with agrochemicals on the antioxidant defense system in rat

It is known that the presence of pesticides may alter the reproductive performance of animals. We studied the effect of chronic pesticide exposure in rats injected i.p. for 5 weeks with doses between 1/50 and 1/250 LD50 of dimethoate, glyphosate and zineb, either alone or in combination. All tested agrochemicals increased the oxidative stress status in the plasma, liver, and testes, and also modified hormonal parameters involved in reproductive function. The increase in oxidative stress and damage biomarker levels, as well as the alteration of the antioxidant defence system decreased testosterone, FSH and LH levels in the plasma of pesticide-treated rats. These effects were more pronounced when pesticides were administered in combination, and should be considered indicative of involuntary exposure to residual agrochemicals.     

Nanodisks protect amphotericin B from ultraviolet light and oxidation‐induced damage

BACKGROUND: Macrolide polyene antibiotics possess potent broad‐spectrum antifungal properties. Use of these agents in the field or in controlled environments is impeded by their poor water solubility and susceptibility to oxidation‐ and/or light‐induced degradation. While typically used for human disease therapy, there is potential to expand the utility of polyene macrolide antibiotics, such as amphotericin B, for control of fungal disease infestation in agricultural settings. Thus, the susceptibility of this antibiotic to exposure‐induced activity loss was evaluated. RESULTS: Incubation of the prototype polyene amphotericin B (AMB) with phospholipid vesicles and apolipoprotein A‐I results in the formation of nanoscale complexes, termed nanodisks (NDs), capable of solubilizing significant quantities of AMB. To evaluate whether AMB incorporation into NDs conferred protection against light‐ or oxidation‐induced damage, yeast growth inhibition assays were conducted. Compared with AMB solubilized in detergent micelles, AMB incorporated into NDs was protected from damage caused by exposure to UV light as well as by KMnO₄‐induced oxidation. Furthermore, AMB‐NDs inhibited growth of the turfgrass fungus Marasmius oreades Fr. CONCLUSION: Results suggest that this water‐soluble formulation of a natural, biodegradable, antifungal agent represents a potential cost‐effective, non‐toxic and environmentally friendly substitute for chemical agents currently employed to control a range of fungal infestations. Copyright © 2009 Society of Chemical Industry     

Fenthion induced-oxidative stress in the liver of adult rats and their progeny: Alleviation by Artemisia campestris

Fenthion (FEN) is an organophosphate insecticide used in both agricultural and urban areas throughout the world including Tunisia. Recent investigations have proved the crucial role of natural antioxidants to prevent the damage caused by toxic compounds. In this study, we investigated the role of Artemisia campestris (Ac) leaf powder in protection against oxidative damage and hepatotoxicity induced by fenthion in female rats and their pups. Female Wistar rats were divided into four groups: group I served as controls which received standard diet, group II received orally FEN 551 ppm, group III received both 551 ppm of FEN and experimental diet (5% Artemisia) and group IV received experimental diet (5% Artemisia). Oral administration 551 ppm of FEN by drinking water to adult rats caused hepatotoxicity as monitored by the increase in the levels of hepatic markers enzymes (transaminases and lactate dehydrogenase), total cholesterol (TC) and triglycerides (TG), as well as hepatic malondialdehyde (MDA) levels thus causing a drastic alteration in antioxidant defence system. Particularly, the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) and the level of reduced glutathione (GSH) increased by FEN. These biochemical alterations were accompanied by histological changes marked by leucocytes infiltration, sinusoidal dilatation (moderate peliosis), granuloma inflammatory disorders and necrosis in hepatocytes of dams. While, slight leucocytes infiltration was shown in pups. Treatment with Ac prevented the liver damage induced by FEN, as revealed by inhibition of hepatic lipid peroxidation accompanied by an improvement of liver histopathological changes, CAT and GPx activities except GSH and SOD which were not modified. It could be concluded that A. campestris is promising a protective agent against hepatotoxicity during the exposure to fenthion.     

Oxidative stress response and histopathological changes due to atrazine and chlorpyrifos exposure in common carp

Atrazine (ATR) and chlorpyrifos (CPF) are the most common pesticides found in freshwater ecosystems throughout the world. Herein, we investigated the oxidative stress responses and histopathological changes in the liver and gill of common carp after a 40-d exposure to CPF and ATR, alone or in combination, and a 20-d recovery treatment. We found that exposure to ATR, CPF or their mixture for 40 d could induce decrease in antioxidant enzyme (SOD, CAT and GSH-Px) activities and increase in MDA content in a dose-dependent manner in the liver and gill of common carp. Especially with regard to the pathological changes, the tissue damage increased in severity in a dose-dependent manner. The liver tissue of common carp revealed different degree of hydropic degeneration, vacuolisation, pyknotic nuclei, and fatty infiltration. The gills of common carp displayed varied degrees of epithelial hypertrophy, telangiectasis, oedema with epithelial separation from basement membranes, general necrosis, and epithelial desquamation. After a 20-d recovery treatment, the antioxidant enzyme activities and MDA content were significantly lower (p < 0.05) than in the corresponding exposure groups in all of the highest doses, but not in the lower doses. To our knowledge, this is the first report of subchronic oxidative stress and histopathological effects caused by ATR, CPF and their mixture in the common carp. Thus, the information presented in this study is helpful to understand the mechanism of ATR-, CPF- and ATR/CPF-mixture-induced oxidative stress in fish.