产气荚膜梭菌ε毒素的细胞毒机制及致病机理的研究进展

产气荚膜梭菌ε毒素（Epsilon toxin ，ETX）由B、D型产气荚膜梭菌产生并分泌至宿主动物体内，在临床上主要症状为肠毒血症．ETX属于以七聚体形式存在的β‐样成孔毒素，它能够形成由14个β折叠片组成的“β‐桶状”结构，这个“β‐桶状”结构可以插入真核细胞的质膜形成穿孔．在细胞水平，ETX能够迅速使细胞膜肿胀、多种细胞器破坏，最终导致靶细胞的坏死．在哺乳动物体内，ETX能够使哺乳动物血管产生水肿，从而穿透血脑屏障而聚积在动物肾和脑中，导致机体随着谷氨酸盐的释放而产生过度兴奋，这一系列反应的发生可以引起机体出现脑水肿和肾衰竭，最终导致动物的死亡．目前， ETX备受关注的主要原因不仅仅因为它是一种β‐样成孔毒素，而是可以作为潜在的一种工具类药物，经改造后可以携带治疗药物在短时间内靶向性地到达哺乳动物脑和中枢神经系统，继而为脑和中枢神经系统疾病的治疗提供新的方向．结合国内外相关研究，对ETX细胞毒机制及致病机理进行了综和评述．     

Zinc antagonizes the effect of botulinum type A toxin at the mouse neuromuscular junction

Summary Zn²⁺ (10–100 M) elevated the frequency of miniature end-plate potentials (MEPPs) in the mouse diaphragm. The effect did not depend on external Ca²⁺. Botulinum type A toxin (BTX_A, 50 ng/ml) abolished MEPPs almost completely within 30 min. Zn²⁺ (100 M) restored MEPPs and increased their frequency after they had been abolished by BTX_A in Ca²⁺-free solutions. The antagonistic effect of Zn²⁺ in the Ca²⁺-free solution was reduced by exposing the diaphragm to the toxin in the Ca²⁺-free solutions containing high K⁺. Thus, the action of BTX_A is probably enhanced by depolarization of the motor nerve terminals.     

Inhibition by tetanus and botulinum A toxin of the release of [3H]noradrenaline and [3H]GABA from rat brain homogenate

Summary Rat brain homogenate was preloaded with [³H]noradrenaline or [³H]GABA and stimulated with high K⁺. Tetanus toxin and botulinum A neurotoxin partially prevent the evoked [³H]noradrenaline release in the same range of toxin concentrations starting below 10^–10M. In contrast, release of -amino butyric acid (GABA) is much more sensitive to tetanus than to botulinum A toxin.     

Non-host-selective fungal phytotoxins: Biochemical aspects of their mode of action

During the last decade increasing attention has been directed towards the biochemical mechanisms responsible for the biological activity of phytotoxins. Studies on the mode of action of some non-host-selective phytotoxins, some following on from previous observations, have demonstrated a very specific interaction with particular components of the cell machinery, and have suggested the possible use of these phytotoxins as tools for the investigation of important biochemical processes. This review article reports and discusses results of studies carried out in the 1980s with seven non-host-selective fungal toxins: brefeldin A, cercosporin,Cercospora beticola toxin, fusicoccin, ophiobolins, tentoxin, and zinniol. Each of these interferes with the life of the host by interacting with a different biochemical target.     

棉花黄萎病毒素在早期抗病性检测中的应用研究

用棉花黄萎病（Ｖ．ｄａｈｌｉａｅ）毒素,处理不同抗性品种二叶期幼苗,结果表明,黄萎病毒素对棉花幼苗有明显致萎作用,其萎蔫指数与田间病情指数呈显著正相关,同时发现黄萎病毒素对种子发芽也有明显的抑制作用     

卟啉杀虫剂对稻蝗的毒杀作用及机理初探

以太原晋源区的中华稻蝗为材料，用以5-氨基乙酰丙酸(ALA)为主要成份的卟啉杀虫剂作用蝗虫，7d内处理组雄虫全部死亡，而对照组雄虫死亡数约为一半，雌虫死亡数在低浓度下无明显差异．用荧光检测法和考马斯亮蓝蛋白测定法对试虫作进一步的毒性分析，发现卟啉杀虫荆作用于蝗虫后，导致雄虫体内每克组织蛋白含量与对照组相比显著降低，A分析组平均降低73．049mg／g，B分析组降低106．271mg／g．雌虫体内每克组织蛋白含量与对照组相比下降不显著，A分析组平均降低22．741mg／g，B分析组为6．640mg／g．由此得知，卟啉杀虫剂对试虫的作用效果与试虫体内每克组织蛋白含量呈相关关系．此外，分析表明，卟啉杀虫荆作用于试虫后，处理组与对照组相比，试虫体内每毫克蛋白原卟啉Ⅸ(PpⅨ)的含量普遍提高，这一点与Constantin A．Rebeiz的部分实验结果基本吻合．同时还发现，A分析组中雄虫平均每毫克蛋白PpⅨ含量处理组比对照组高0．351gg／mg，雌虫的高0．277pg／mg，前者比后者多0.074pg／mg．B分析组中雄虫平均每毫克蛋白PpⅨ含量处理组比对照组高0．171μg／mg，雌虫的高0．103μg／mg，前者比后者高0．068μg／mg．从实验结果可以看出卟啉杀虫剂对试虫的作用效果与试虫体内每毫克蛋白中PpⅨ含量呈相关关系，结果表明卟啉杀虫剂对试虫的作用效果是由PpⅨ的光敏毒性引起的．     

稻瘟病菌粗毒素对水稻幼胚愈伤组织的影响及抗性筛选

利用目前稻瘟病不同的优势小种菌株的液体培养提取的粗毒素对水稻幼胚进行处理,稻瘟病菌粗毒素提取液对水稻幼胚的愈伤的诱导和分化的有明显的抑制效应。随着毒素浓度的增加,水稻胚性愈伤获得率和分化能力显著降低。在诱导培养基中加入毒素对幼胚的筛选取效果较好,可以获得较多的胚性愈伤和较多的分化苗。培养基中毒素的浓度处理以30%效果好。水稻幼胚的抗性筛选过程中胚性愈伤获得和分化苗数较高,是很好的培养材料;而且不同的水稻品种产生的耐性不同,并可以同时筛选出抗稻瘟病的突变体。     

百日咳毒素的等电点测定及层析分离

百日咳毒素是百日咳杆菌(Bordetellapertussis)产生的一种主要毒力因子,也是百日咳菌苗的主要成分之一.用等电聚焦法测得其等电点为pH6 8.将百日咳杆菌液体培养液在等电点盐析后,通过DEAE-Sephadex-A50阴离子交换剂进一步分离纯化了百日咳毒素.ELISA测定其比活力表明,3批样品的提纯倍数分别为1 47,1 37和1 36.     

利用溃疡菌毒素筛选抗溃疡病杨树品种

通过测定杨树溃疡病毒素粗提物处理的6种杨树枝务的叶片电导率、脯氨酸含量、多酚氧化酶和过氧化物酶的活性，研究了毒素的致病性及不同杨树品种的抗病性．结果表明：叶片电导率越大，杨树的抗性越差；叶片脯氨酸含量越多，杨树抗性越强；多酚氧化酶和过氧化物酶的活性越强，杨树抗性越好．这4个指标均能很好的反映杨树不同品种对溃疡菌的抗病性．这表明，用溃疡菌毒素筛选抗溃疡病杨树品种具有可行性．     

Conotoxins of the O-superfamily affecting voltage-gated sodium channels

The venoms of predatory cone snails harbor a rich repertoire of peptide toxins that are valuable research tools, but recently have also proven to be useful drugs. Among the conotoxins with several disulfide bridges, the O-superfamily toxins are characterized by a conserved cysteine knot pattern: C-C-CC-C-C. While ω-conotoxins and κ-conotoxins block Ca²⁺ and K⁺ channels, respectively, the closely related δ- and μO-conotoxins affect voltage-gated Na⁺ channels (Na_v channels). δ-conotoxins mainly remove the fast inactivation of Na_v channels and, thus, functionally resemble long-chain scorpion α-toxins. μO-conotoxins are functionally similar to μ-conotoxins, since they inhibit the ion flow through Na_v channels. Recent results from functional and structural assays have gained insight into the underlying molecular mechanisms. Both types of toxins are voltage-sensor toxins interfering with the voltage-sensor elements of Na_v channels. Received 27 December 2006; received after revision 30 January 2007; accepted 19 February 2007