Tetanus toxin does not affect the release of noradrenaline and taurine from rat cerebral cortex slices evoked by high K+ and Na+-free media

Summary Noradrenaline and taurine release from superfused rat cerebral cortex slices was stimulated by potassium ions, veratrine, ouabain and omission of sodium ions. Tetanus toxin enhanced only the ouabain-evoked calcium-dependent noradrenaline release and the ouabain-evoked calcium-independent taurine release. The uptake of both was marginally affected.     

Tetanus intoxication causes an increment of serotonin in the central nervous system

Summary Mice injected with tetanus toxin (TTx) showed an increase of 5-hydroxytryptamine (serotonin, 5-HT) levels in the central nervous system. The increment was not uniform thoughout the central nervous system. Particularly significant were the 25% and 80% increases observed, respectively, in whole brain and spinal cord. The levels of dopamine and norepinephrine remained unchanged. The subsequent studies of 5-HT turnover revealed a synthesis rate in the tetanic animals that was almost double that of controls. The degradation rate of the amine as well as the levels of 5-hydroxyindolacetic acid were unaffected.     

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     

Cholera toxin structure, gene regulation and pathophysiological and immunological aspects

Many notions regarding the function, structure and regulation of cholera toxin expression have remained essentially unaltered in the last 15 years. At the same time, recent findings have generated additional perspectives. For example, the cholera toxin genes are now known to be carried by a non-lytic bacteriophage, a previously unsuspected condition. Understanding of how the expression of cholera toxin genes is controlled by the bacterium at the molecular level has advanced significantly and relationships with cell-density-associated (quorum-sensing) responses have recently been discovered. Regarding the cell intoxication process, the mode of entry and intracellular transport of cholera toxin are becoming clearer. In the immunological field, the strong oral immunogenicity of the non-toxic B subunit of cholera toxin (CTB) has been exploited in the development of a now widely licensed oral cholera vaccine. Additionally, CTB has been shown to induce tolerance against co-administered (linked) foreign antigens in some autoimmune and allergic diseases. Received 25 October 2007; accepted 12 December 2007     

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。     

地表水中藻毒素的监测与控制

随着大量含氮和磷的废水流入湖泊和江河,导致淡水污染现象日趋严重.污染的最主要危害是释放多种藻毒素,因此如何有效控制、去除藻毒素是摆在中外环境科学领域的一个难题,目前水体中藻毒素的监测方法主要有生物法、化学法、免疫法等;控制的方法主要有常规净水工艺、生物处理、光降解与光催化氧化以及臭氧氧化等.     

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．     

深圳大亚湾麻痹性贝类毒素成分特征

目的：研究贝类的麻痹性贝毒素（ＰＳＰ）成分特征,探讨局部海域内贝毒素与藻毒素间关系。方法：用高效液相色谱（ＨＰＬＣ）法对深圳大亚湾两个贝类养殖区的华贵栉孔扇贝（Ｃｈａｌｍｙｓ ｎｏｂｉｌｉｓ）和翡翠贻贝（Ｐｅｒｎａ ｖｉｒｉｄｉｓ）消化腺所含的麻痹性贝类毒素进行定性和定量分析。结果：大亚湾两种贝类的麻痹性贝毒素成分特征相似,主要成分为低毒力的Ｎ－磺酸氨甲酰基毒素Ｂ１（ＧＴＸ５）和Ｃ１－２,占毒素总     

肉毒毒素肠溶微球灭鼠剂的制备及性质研究

以肉毒毒素作为主体灭鼠药物,用丙烯酸树脂Ⅱ号为肠溶材料,通过相分离法制备肠溶微球;考察了微球的形态特征、包封率、载体回收率、抗酸能力、体外溶出度以及包封蛋白的活性保留度,并经拌饵投食试验,表明该制剂能有效地提高毒蛋白在肠胃中的稳定性,使其毒力(LD50)提高100倍以上,并且有较强的缓释作用．