Cloning and Sequencing of cnf1 from Escherichia coli Incriminated in Mink and Bovine Colibacillosis

Colibacillosis is responsible for significant losses to the mink and cattle industries. Previous work in our laboratory and by others has suggested that possession of cnf1, the gene encoding cytotoxic necrotizing factor (CNF1), may contribute to the virulence of isolates of E. coli from mink and cattle. The cnf1 gene from E. coli isolated from a mink with colisepticaemia and a bovid with scours was amplified and cloned as a 3.5 kb fragment, and the fragment was sequenced. The cnf1 sequences from the mink and bovine isolates of E. coli were compared to each other and to cnf1 sequences of E. coli from urinary tract and diarrhoea-associated infections of humans. The difference was only 7 nucleotides between the cnf1 sequences of the mink and bovine isolates of E. coli, which translated into 7 differences in amino acids. The cnf1 sequence of the mink isolate of E. coli had 15 nucleotide differences from the cnf1 sequences of the human isolate of E. coli (GenBank X70670), which translated into 11 differences in amino acids between these proteins. The cnf1 sequence of the bovine isolate of E. coli had 14 nucleotide differences from the cnf1 sequence of the human isolate of E. coli (GenBank X70670), which translated into 10 differences in amino acids between these proteins. The highly conserved sequences of the amino acids of CNF1 proteins make them a promising target for detection and control of the CNF1-producing E. coli involved in disease among various host species.     

去除效价的土霉素药渣亚慢性毒性试验

用小鼠对去除效价的土霉素药渣进行亚慢性毒性试验,探讨在处理土霉素药渣过程中是否产生有毒物质。结果表明,饲喂处理后药渣的小鼠与饲喂原药渣的小鼠各脏器系数没有显著差异(P0.05),证明经过处理的药渣不仅与原药渣的各项指标相同,而且使残留效价大幅度降低。     

Work safety in plastination

In this article, information is given on potential physical and health hazards in the steps of the silicone cold temperature method, often referred to as “S 10 Standard Method.” The main potential hazards related to plastination, as well as recommended measures to effectively avoid explosion and health hazards are discussed. Some specialty chemicals pose chronic health hazards. Exposure to these chemicals can be avoided by standard laboratory hygiene, that is wearing personal protective equipment like safety goggles and protective gloves. Inhalation hazard, for example when working at open dehydration containers or when opening a gas curing box, is preferentially avoided by the action of an appropriate ventilation system. Acetone is the standard solvent used for dehydration and defatting of the specimens to be plastinated. Like for other flammable liquids, explosion protection must be considered when handling acetone. The concentration of acetone vapour in the air must be kept below the lower explosion limit through appropriate room or workplace ventilation. Furthermore, all potential sources of ignition should be removed from the explosion hazard zone. If electrical devices need to be operated inside the explosion hazard zone, they need a special design and approval. The conditions covered by this approval can be found on the identification plate of the individual device.     

HACCP体系在冻煮龙虾仁加工中的应用

针对不同类型水产品加工中HACCP的应用特点,通过对冻煮龙虾仁加工流程的每道工序进行危害分析,确定了关键控制点,制定了HACCP工作计划表,构建了冻煮龙虾仁的HACCP管理体系模式。     

农药“毒死蜱”对家蚕“两广二号”残毒期的统计分析

应用SPSS统计学软件,进行了40％“毒死蜱”农药对“两广二号”家蚕残毒期的曲线拟合分析,及残毒期前后的茧质方差分析。结果表明：“毒死蜱”400mg·L^-1和200mg·L^-1浓度的残毒期分别是24天和19天,在它们之后的蚕茧质量正常。它们的数学模型分别为指数曲线方程：y=170．63690-0．1645x和y=241．1498e^0.2332x。该方法克服了以往农药对家蚕残毒期的确定无数学模型可循,或使用的BASIC编程方法陈旧、繁杂的不足,是一种计算简便、准确和严谨的农药残毒期的分析新方法。     

Decaying toxic wood as sodium supplement for herbivorous mammals in Gabon

African rainforest harbors herbivores at high density. However, because plants and soils typically lack in some essential minerals, rainforest is not always a suitable habitat for herbivores. How they fulfill the mineral requirements is therefore an important question to animal ecology and conservation. Although large marshes, called ‘bais’, are often mentioned as efficient mineral-resource, little information on other sodium resources has still been available. Our laboratory works and field surveys found that a peculiar item, decaying wood stumps of Anthostema aubryanum, played as a major sodium resource for herbivores in Moukalaba-Doudou National Park, Gabon. When A. aubryanum is alive, the sodium content of its bark is low and its latex is toxic. Sodium is accumulated in decaying stumps (mean=1,343 mg/kg dry matter). Eight herbivores visited stumps to ingest the dead wood. Fecal sample analysis revealed that western lowland gorillas, a species most-frequently using the stumps, consumed large amount of the dead wood as regular food. Our findings suggest that decaying A. aubryanum is critical sodium-resources and is a key species for herbivores in our study area. Importance of the A. aubryanum may be particularly large there, because it is a limited sodium-rich material that is available year round. Our study site is known as the site where the densities of several herbivores are among the highest at Central Africa. The relatively high herbivores density in our study site may partly depend on decaying A. aubryanum as sodium resources.     

刍议椰心叶甲的危害与防治

前些年,海南、广东等省曾遭受了严重的"椰瘟"——椰心叶甲的危害,给我国的棕榈科植物资源和自然生态环境造成了严重的破坏,后经过长期不懈地努力使疫情得到有效地控制,生态基本实现动态平衡,现又出现反弹现象。结合自身的经验刍议椰心叶甲的危害与防治。     

4种植物精油对瓜实蝇毒杀及驱避作用

瓜实蝇 Bactrocera cucurbitae (Copullett)是我国瓜类蔬菜的重要入侵害虫, 为筛选出对瓜实蝇具有毒杀及驱避作用的植物精油, 室内测定了4种植物精油在不同浓度下对瓜实蝇的毒杀及产卵驱避效果, 并进行了田间验证。结果表明:4种植物精油对瓜实蝇成虫的毒杀效果随精油浓度升高而升高, 浓度为7 mg/mL和10 mg/mL的肉桂精油对瓜实蝇的毒杀效果极显著高于其他精油, 处理后24 h瓜实蝇校正死亡率分别为75.9%和100%;雌虫对冬青精油的嗅觉反应率为93.3%, 显著高于紫苏精油和山苍子精油。不同植物精油对雌虫产卵的驱避效果不同，当植物精油浓度为10 mg/mL时, 冬青精油对雌虫的产卵驱避率为69.04%, 显著高于其他精油。田间试验结果显示:不同植物精油对瓜实蝇成虫具有一定防控效果, 但处理间差异不显著, 可能是由于田间环境复杂、植物精油理化性质存在差异等因素导致。     

水生生物监测农药毒性效应研究进展

农药毒性不仅降低水环境质量、影响水生生物的生长繁殖,更有甚者会给人体健康带来威胁。目前对农药毒性效应的监测方法主要有理化检测法和生物监测法两种,其中生物监测因其快捷、简便等优点,已成为现今研究的热点。通过对近年来国内外大量文献的研究,对水生生物监测农药毒性效应现状进行总结分析,并对其发展前景进行预测展望。     

油库静电危险源辨识及其危害防护措施

针对油库的静电火灾爆炸事故难以预防的难题,分析了油库中存在的静电危险源及内容,提出了“点、线、面”静电危险源分类辨识方法。分析了“点、线、面”危险源会发生的不同静电放电形式,以及放电可能发生的部位。阐述了油库静电火灾爆炸事故发生的原理性和流程性机理,提出了油库可能引起静电事故的原因,并给出了油库静电事故的安全预防措施：接地与跨接、安全检查、防止爆炸性混合物形成、控制流速等,有助于避免和减少静电火灾爆炸事故的发生。