德国小蠊菊酯抗性与钠离子通道机制研究进展

菊酯杀虫剂长期使用会导致昆虫产生抗性,严重影响德国小蠊等有害昆虫的治理。德国小蠊产生菊酯击倒抗性(kdr)与钠离子通道发生kdr突变有关。本文介绍了德国小蠊钠离子通道的跨膜分子结构、功能和基因表达调节方式,同时讨论了钠离子通道kdr突变导致德国小蠊产生菊酯抗性的机制。理解钠离子通道kdr突变机制,不仅为德国小蠊种群抗性监控提供有效分子靶标,还可为新型杀虫剂研制提供思路。     

site-3毒素对心肌细胞钠通道的电生理效应与作用机制

site-3毒素是从海葵和蝎子等生物中提取出来的多肽类毒素,能够与电压门控钠通道IV区域的S4段附近site-3位点结合,从而抑制钠通道的快速失活。本文综述了site-3毒素作用于心肌细胞钠通道的电生理效应及与心肌细胞钠通道相互作用的分子机制。     

家蝇拟除虫菊酯抗药性的分子生物学监测

目的　建立一种可以早期检测昆虫拟除虫菊酯抗药性的方法 ,以利于抗药性的控制。方法　采用聚合酶链反应 (PCR)方法 ,用自行设计的特异引物 ,对昆虫的钠离子通道基因进行扩增。结果　共检测敏感家蝇和溴氰菊酯抗性家蝇各 2 0只 ,在所有抗性家蝇的钠离子通道基因中均扩增出特定大小基因片段 ( 183bp) ,表明基因发生了抗性突变。而在所有敏感家蝇的钠通道基因中均未扩增出该基因片段 ,表明未发生基因突变。结论　PCR能够在短时间内完成对昆虫拟除虫菊酯抗性的检测 ,为早期监测昆虫对拟除虫菊酯的抗药性提供了快速可行的方法。     

麻痹性贝类毒素小鼠生物法检测中位数法与均数法差异性比较

麻痹性贝类毒素（Paralytic shelfrish poison，PSP）广泛分布于全球各大海域，是一类对人类生命健康危害极大的海洋生物毒素，也是目前危害最大的贝类毒素。织纹螺对PSP有独特的富集能力，近年来，沿海地区时有因食用被PSP污染的贝类而中毒的事件发生。     

广州市售贝类麻痹性贝毒和腹泻性贝毒污染状况分析

目的对广州市售双壳经济贝类麻痹性贝毒(PSP)和腹泻性贝毒(DSP)污染状况进行为期一年的抽样调查,了解其食用安全性。方法采用AOAC推荐的小鼠生物检测法进行PSP和DSP的毒力测定,采用HPLC进行PSP成分分析,根据FAO、日本和欧盟水产食品卫生要求及我国渔政渔港监督管理局制订的贝类安全食用标准对贝类水产品的食用安全性进行评价。结果在所调查的7种贝类中,有2种染有PSP,毒素含量在安全食用范围内,毒力大小随季节而变化,春冬两季含量相对较高;7种贝类中有6种共计36个样品染有DSP,有10个样品毒素含量超出安全食用标准,春冬两季染毒率较高。结论广州市售贝类PSP含量和检出率整体水平较低;DSP检出率稍高,毒素含量也较高,应引起有关部门的关注,加强DSP监测工作。     

德国小蠊钠离子通道抗性研究进展

德国小蠊在医学与经济方面的重要性和危害性促使人们对其进行广泛的化学防治,但随之产生严重的抗性.该文以德国小蠊钠离子通道抗性即击倒抗性(knockdown resistance,kdr)为主题,重点论述了德国小蠊kdr抗性的发现历史、分子与进化机制,扼要介绍了钠离子通道结构特征、kdr突变的功能研究方法以及近期所取得的代表性研究结果.此外,概述了该领域的最新研究方向及结果对德国小蠊防制、抗性监测与治理等的理论与指导意义.     

蚊虫抗药性分子机制研究进展

蚊虫是重要的医学昆虫,可以通过叮咬传播疾病(例如疟疾、丝虫病、登革热等),其行为与人类生活息息相关.由于长久以来大量、广泛地使用杀虫剂,使蚊虫抗性日益严重.蚊虫的抗性机制主要有靶标抗性(包括神经轴突钠离子通道、乙酰胆碱酯酶和γ-氨基丁酸受体氯离子通道的突变)和代谢抗性(包括非特异性羧酸酯酶、细胞色素P450和谷胱甘肽-S-转移酶的活性增加)两方面.现对这些机制的研究进展进行综述,试图全面了解大量、广泛使用杀虫剂之后蚊虫抗性产生的分子机制.     

连云港地区织纹螺食物中毒的流行病学研究

目的：分析连云港地区织纹螺食物中毒的流行病学特征,探讨预防织纹螺食物中毒的方法。方法：收集近年织纹螺中毒资料,对连云港地区织纹螺进行形态学鉴定。应用生物测定法检测螺肉中麻痹性贝类毒素(PSP)含量。结果：连云港海域生长4种织纹螺,其中半褶织纹螺导致10起中毒,中毒表现主要是下行性神经麻痹,毒素对温度不敏感。结论：鉴于海洋污染的严重性,为保障海贝的食用安全,应对贝类进行毒素安全指标检测。     

家蝇对高效氯氰菊酯抗药性机制的探索

目的研究揭示家蝇对高效氯氰菊酯抗药性机制。方法生物测定、遗传学、生物化学以及分子生物学方法。结果经过25代选育，选育品系家蝇对高效氯氰菊酯抗性高达4419．07倍；抗性遗传为隐性遗传；抗性家蝇羧酸酯酶比活力是敏感家蝇的2．436倍；抗性品系的钠离子通道基因发现了2个氨基酸的改变。结论家蝇对高效氯氰菊酯抗性可能与钠离子通道基因的突变有关。     

贝类麻痹性毒素的检测

海洋软体动物贝类麻痹性毒素（paralytic shellfish poison，PSP）的检测方法，通用的方法为生物测定法，即根据小鼠注射贝类提取液后的死亡时间，查出相应的鼠单位并进行体重校正后，计算确定每100g贝肉中PSP毒素的含量。这种方法的局限性是以小鼠活体实验为基础，判定贝类产品的毒性大小。由于小鼠个体差异，使得检测结果具有高变异性和低敏感性。因此，欧盟对贝类产品PSP含量，特别规定了允许80μg／100g的限量。目前，我国检测PSP含量的方法SN0352—95《出口贝类麻痹性贝类毒素（PSP）检验方法》和SC／T3023—2004无公害食品《麻痹性贝类毒素的测定》仍采用小鼠生物测定法。为了准确检测贝类等水产品中PSP毒素的含量，本次用ELISA法进行实验，取得了满意的结果，方法如下：     

麻痹性贝毒在广州市售经济贝类中污染状况分析

目的通过对广州市黄沙海产品批发市场7种经济贝类为期一年的麻痹性贝毒(PSP)污染状况的调查分析,了解海产品食用的安全性。方法毒性测定按照AOAC小白鼠法进行,成份分析利用高效液相色谱(HPLC),安全性评价采用联合国粮农组织(FAO)及我国渔政渔港监督管理局制定的贝类安全食用标准(4MUg肉)。结果在调查的84份贝样中,染毒贝整体毒力(消化腺与肉的加权平均毒力)低于4MUg肉,毒素最高含量仅为184MUg肉,所有贝类均在安全食用范围之内。染毒贝类主要为栉孔扇贝(ChlamysMimachlamysnobilis)和嵌条扇贝(Pectenalbicans)。毒素在2个种9份样品的消化腺中检出,某些样品肌肉组织出现小白鼠毒性反应。一份样品消化腺中毒素含量高达1452MUg,高效液相色谱(HPLC)分析表明,该样品毒素成份主要为B1、GTX23、GTX14及C类。结论广州市市售鲜贝PSP含量和检出率整体水平均较低;贝中消化腺毒素含量及检出率明显高于肌肉,个别腺体毒素含量超出标准。毒素分布存在季节性差异,春季毒素比较强,夏秋季检出率高。因此有针对性的加强贝毒监测非常必要。     

麻痹性贝类毒素细胞检测法的建立

目的:麻痹性贝类毒素的N-2a细胞检测方法的建立并确定可能的检测限值。方法:使用不同浓度毒素标准品结合藜芦定和乌本苷共同作用对数生长期的N-2a细胞,通过cck-8试剂盒检测细胞毒性,确立细胞检测方法的检出限及比较各毒素作用大小,并同步利用小鼠生物法进行验证,通过精确记录小鼠死亡时间,比较各毒素的毒作用大小。结果:麻痹性贝类毒素能明显降低藜芦定和乌本苷的细胞毒性,且具有剂量-反应关系,通过比较得出毒素各成分毒性大小为:neoSTX>STX>dcSTX>GTX1,4>GTX2,3>dcGTX2,3;小鼠生物法的毒作用平均死亡时间为:neoSTX组(6.5 min),GTX1,4组(8.0 min),STX组(9.0 min),dcSTX组(15 min);GTX2,3组和dcGTX2,3组未见动物死亡。结论:细胞检测与小鼠生物法具有较好的一致性,表明所建立的细胞检测法可行,且细胞毒性试验检测方法具有较高的灵敏度,最低检出限值可达到10-9mol/L剂量水平,其中浓度在10-6~10-8mol/L间具有较好的线性。     

Identification of a point mutation associated with pyrethroid resistance in the para-type sodium channel of Triatoma infestans, a vector of Chagas' disease

The voltage-gated sodium channel is the target site of pyrethroid insecticides. Point mutations in the domain II region of the channel have been implicated in pyrethroid resistance of several insect species. We identified the sequence of domain II from the para sodium channel in Rhodnius prolixus, a vector of Chagas' disease. With this information, we cloned and sequenced the domain II of the sodium channel from the other main Chagas' disease vector: Triatoma infestans. We also identified the presence of a resistance-conferring mutation (L1014F) in a pyrethroid-resistant population of T. infestans from Argentina, and present a PCR-based method to detect this mutation in individuals from field populations. These findings have important implications for the implementation of strategies for resistance management, and for the rational design of campaigns for the control of Chagas' disease transmission.     

中国沿海的贝毒问题研究

我国对贝毒的调查研究工作目前正在开始，除了已查明江瑶具有内源性贝毒之外，主要的研究工作集中在赤潮产生的麻痹性贝毒（ＰＳＰ）上面，ＰＳＰ中毒案例主要发生在中国南方的浙江、福建、广东及台湾等地，其中有一些案例是致命性的。科研人员研究了广东省各种贝类中ＰＳＰ的含量，组织中分布及季节变化的情况，对其组份进行分析发现主要成份为ＳＴＸ，ｎｅｏＳＴＸ及ＧＴＸ１～４等。在我国沿海已发现了三种产生ＰＳＰ的毒藻，其中的Ａｌｅｘａｎｄｒｉｕｍｔａｍａｒｅｎｓｅ已分离出孢子并培养出单株克隆体供研究用，值得注意的是，我国沿海还发现过产生腹泻性贝毒，神经性贝毒及失忆性贝毒等毒源藻类，应提高警惕其形成“赤潮”，并在贝体内大量积累的可能性     

Cluster analysis of toxins profile pattern as a tool for tracing shellfish contaminated with PSP-toxins

Paralytic shellfish poisoning (PSP) is one of the most lethal biotoxin-induced diseases worldwide, which may pose serious public health threat and potential devastating economic damage on fisheries industry in the affected region(s). To prevent the importation of PSP contaminated shellfish to a community, detailed documentation on the supply chain and routine surveillance systems are, in principle, crucial measures to protect people from this intoxication. However, difficulties have always been encountered on the traceability of the source/origin of contaminated shellfish.In the present study, we reported the potential application of PSP-toxins profiles with similarity analysis that can be used to identify epidemiological linkage between shellfish samples collected from markets and patients during a PSP outbreak. PSP-toxins were identified and quantified by ion-pair chromatographic separation followed by post-column oxidation to fluorescent imino purine derivatives. Samples from a PSP incident and other surveillance samples collected in our past 7-year record were also compared for their similarity in PSP-toxins profiles patterns. Molar distributions (nmol%) of 10 PSP-toxins were analyzed by Unweighted Pair Group Method with Arithmetric averages (UPGMA). Three prominent clusters emerged with similarity levels reaching over 80% for each, suggesting that each group of samples probably originated from a same source/batch. The PSP-toxins profiles and toxicities determined from surveillance samples could provide premonitory clues on the occurrences of PSP incident and outbreak with corresponding toxin profiles in the later time. Due to species-specific characteristics of PSP-toxins composition and profile in shellfish under varieties of environmental and physiological conditions, PSP-toxins profile can be a specific and useful biochemical indicator for tracing PSP contaminated shellfish provided that spatio-temporal occurrence patterns of toxins profiles are available in a databank for inter-laboratory comparison and standardized methodologies such as consentaneous toxins extraction and identification criteria are used for analysis and comparison.     

宁波市有毒织纹螺地域分布分析

目的了解宁波市有毒织纹螺的分布。分析各栖息地有毒织纹螺的毒性变化，为控制织纹螺中毒提供依据。方法采用美国分析化学家学会（AOAC）和中国进出口检验检疫（CIQ）的小鼠生物测试法，以美国食品药物管理局（FDA）的贝类麻痹性毒素（PSP）标准，判定本地织纹螺毒性的强弱，按年观察结果。结果1986～2003年，宁波市127份被检织纹螺中毒素平均含量最高的年份为1991年，达11900MU／100g螺肉，最低年份为1988年，其毒素含量也达403MU／100gN肉，其他年份的毒性波动在一定范围内。不同栖息地毒螺检出率镇海区为31．43％，北仑区为39．29％，宁海县为73．08％，奉化市为25．00％，经统计学处理差异有统计学意义（P〈0．01）；除宁海外，其余3个县（市、区）毒螺检出率差异无统计学意义（P〉0．05）。从新增织纹螺栖息地象山采集的30份织纹螺样品，毒素测定值均≤400MU／100g肉，未检出毒螺。结论宁波市各栖息地的织纹螺带毒严重，是一种引起织纹螺中毒的原因食物。各栖息地织纹螺毒性存在差异，以宁海县的织纹螺带毒最普遍。毒螺的分布和毒性的强弱与地域相关。织纹螺毒素的毒性可消长，但无规律性。     

Update on the frequency of Ile1016 mutation in voltage-gated sodium channel gene of Aedes aegypti in Mexico

We analyzed 790 Aedes aegypti from 14 localities of Mexico in 2009 to update information on the frequency of the Ile1016 allele in the voltage-gated sodium channel gene that confers resistance to pyrethroids and DDT. The Ile1016 mutation was present in all 17 collections, and was close to fixation in Acapulco (frequency = 0.97), Iguala (0.93), and San Nicolas (0.90). Genotypes at the 1016 locus were not in Hardy-Weinberg proportions in collections from Panuco, Veracruz, Cosoleacaque, Coatzacoalcos, Tantoyuca, and Monterrey due in every case to an excess of homozygotes. The high frequencies of this mutation in Ae. aegypti are probably due to selection pressure from pyrethroid insecticides, particularly permethrin, which has been used in mosquito control programs for >10 years in Mexico.     

Altered brain activity in brevetoxin-exposed bluegill, Lepomis macrochirus, visualized using in vivo 14C 2-deoxyglucose labeling

This study investigated the neurological effects of sublethal brevetoxin (PbTx-2) exposure in bluegill (Lepomis macrochirus) by measuring alterations in 2-deoxyglucose (2-DG) uptake in the brains of exposed fish. Changes in regional brain activity were quantified using digitized autoradiographs from exposed and control fish. Brains of brevetoxin-exposed fish had significantly higher labeling of 2-DG than brains of control fish. Regional increases in labeling were observed in the optic lobes, telencephalon, and cerebrum of PbTx-2 exposed fish. From these observations, we conclude that sublethal brevetoxin exposure in vivo in bluegill increases neurological stimulation, measured through quantification of [14C]2-DG uptake in the brain. Increases in the uptake of [14C]2-DG from this study may be indicative of differences in neural activity in the PbTx-exposed fish and are likely associated with the action of PbTx-2 on voltage-gated sodium channels (VGSC), as well as neurological alterations in calcium and neurotransmitter release downstream resulting from VGSC activation. These techniques quantify physiological alterations in fish brain activity resulting from exposure to brevetoxin and possibly other harmful algal bloom toxins.     

Paralytic shellfish poisoning --- southeast Alaska, May--June 2011

On June 6, 2011, the Section of Epidemiology (SOE) of the Alaska Division of Public Health was notified of a case of paralytic shellfish poisoning (PSP) in southeast Alaska. In collaboration with local partners, SOE investigated and identified a total of eight confirmed and 13 probable PSP cases that occurred during May--June 2011. Warnings to avoid noncommercially harvested shellfish were broadcast on local radio and television and displayed at beaches and in post offices, government offices, and businesses throughout the region. Commercially harvested shellfish, which are tested for the presence of PSP-causing toxins, were safe. Because the risk for PSP is unpredictable, persons who consume noncommercially harvested Alaskan shellfish should know that they are at risk for PSP, and suspected cases should be reported promptly to SOE to initiate control measures in the affected area.