蜘蛛多肽毒素研究进展

蜘蛛肽类神经毒素按分子量大小可分为2种,除了黑寡妇蜘蛛毒素属于高分子量多肽,其余的毒素均属于小分子量肽类。不同的多肽毒素其功能不同,它们或仅作用于昆虫,或仅作用于哺乳动物,或对二者皆有影响。本文综述了近十年来这方面的研究成果,根据功能将毒素分成4类,逐一介绍了毒素的结构与作用机制。这些毒素的研究对神经生物学,新药的研究与开发及植物的抗虫育种等方面的发展具有重要的意义。     

蜘蛛肽类神经毒素研究进展

对目前已知一级结构的蜘蛛肽类神经毒素的结构和生理活性作了扼要的介绍,这类毒素基本上可分为短链（33-40个氨基酸残基）和长链（66-77个氨基酸残基）两大类.不同种属蜘蛛的肽类毒素之间在一级结构上同源性很小,在生理活性机制上有较大差异.其中某些毒素可选择性的作用于昆虫或脊推动物神经突触上钙与钠离子通道,显示出在神经生物学和神经药理学研究上有很大的应用前景.     

O-超家族芋螺毒素研究进展

O-超家族芋螺毒素是芋螺毒素中较复杂的超家族之一,它包括δ、μO-、ω-、κ-等若干成员,通常由24-33个氨基酸组成,具有相同的三对二硫键骨架,形成ICK模体,能特异性作用于电压门控离子通道。本文主要对该芋螺毒素生物化学及分子遗传学特征、生理学和药理学特征、结构与性能的关系及应用研究与前景等进行综述。     

动物离子通道毒素与药物开发

就离子通道和动物离子通道毒素的来源、种类、特性及其对新药开发的意义进行了综述。各种来源的动物毒素通常分子量较小,富含二硫键,是直接作用于分子靶标（如离子通道、受体及酶）的小分子蛋白质。很多动物毒素对电压门控离子通道具有高度的专一性和有效性,具有独特、简洁的三维空间结构。其对新药的发现、设计以及寻找潜在的治疗靶标具有重要的指导意义。     

A-超家族芋螺毒素研究进展

芋螺毒素是生物毒素中迅速发展的新领域,是很有价值的药物或药物先导化合物,其中A-超家族芋螺毒素是研究最早、了解较为全面的芋螺毒素家族之一,由于其高丰度、化学多样性、强专一性作用等突出特点成为创新药物发展的宝库。A-超家族芋螺毒素因能选择性阻断nAChRs的某种亚型,使它们可作为鉴定nAChRs及其亚基的有效工具。此外,在药理学方面,A-超家族芋螺毒素除了作为镇痛药物已进入临床研究外,也有望开发成用于治疗焦虑症、帕金森氏病、肌肉紧张和高血压等病症的药物。     

毒菌毒素及其应用价值

毒菌毒素及其应用价值孟国良李凤玲（郑州牧业工程高等专科学校,４５００４５）毒菌,是指不能直接食用的大型有毒真菌。目前全世界已发现毒菌２００余种,我国１８０多种。在这些毒菌中,有不少种含毒轻微或在一定条件下尚可食用,真正能够引起人们食后中毒致死的有３０...     

动物毒素及相关药物研究进展

动物毒素是指有毒动物毒器分泌的毒液中,结构和功能丰富多样的蛋白质和多肽,其具有高活力、高结构多样性、高专一性等特点,是药物开发的重要资源。综述了动物毒素药物的特点以及进入临床药物和候选药物分子的研究进展,同时分析了我国动物毒素类药物研发中需要重视的问题。     

生物毒素的医药应用研究进展

生物毒素是一大类具有重要意义的生物源化学物质,生物毒素研究已发展成为与多种学科交叉的“生物毒素学”新学科,其发展对于生命科学、生源合成化学、化学生物学、化学生态学、医学、药物学都有重要意义,对药物创新研究更具有积极作用。该文概述了生物毒素的种类,详细阐述了生物毒素的医药应用及最新进展,指出了生物毒素在医药研究上的热点。     

稻田蜘蛛研究进展

稻田蜘蛛研究是稻虫生态管理的基础工作之一，从生态学的观点出发，介绍中国近年稻田蜘蛛研究的主要内容及进展，阐明蜘蛛的保护利用在可持续农业发展中的地位和作用，分析稻田蜘蛛生态研究的可行性，探讨蜘蛛群落研究方向，主要任务和应用前景。     

蜘蛛繁殖行为研究进展

蜘蛛的繁殖行为可以分为求偶行为、交配行为、产卵和携卵行为、携幼行为,本文根据国内外研究进展,对蜘蛛的繁殖行为进行简要综述.     

Bacterial toxins and their application

The review deals with the structure of protein bacterial toxins, steps of the toxin molecule interaction with the target cell, molecular mechanisms of the toxic effect, as well as with the fields of application of toxins as research tools and as medicinal preparations.     

海洋生物毒素的药物开发前景

本对海洋生物毒素的研究现状及其在神经系统、心血管系统等方面的作用做了简要的综述,并对海洋生物毒素在药物开发中的应用前景及展望予以探讨。     

Biotechnological applications of brown spider (Loxosceles genus) venom toxins

Loxoscelism (the term used to define accidents by the bite of brown spiders) has been reported worldwide. Clinical manifestations following brown spider bites are frequently associated with skin degeneration, a massive inflammatory response at the injured region, intravascular hemolysis, platelet aggregation causing thrombocytopenia and renal disturbances. The mechanisms by which the venom exerts its noxious effects are currently under investigation. The whole venom is a complex mixture of toxins enriched with low molecular mass proteins in the range of 5–40 kDa. Toxins including alkaline phosphatase, hyaluronidase, metalloproteases (astacin-like proteases), low molecular mass (5.6–7.9 kDa) insecticidal peptides and phospholipases-D (dermonecrotic toxins) have been identified in the venom. The purpose of the present review is to describe biotechnological applications of whole venom or some toxins, with especial emphasis upon molecular biology findings obtained in the last years.     

Biochemical and pharmacological studies on a lethal neurotoxic polypeptide fromPhoneutria nigriventer spider venom

Fractionation ofPhoneutria nigriventer spider venom by gel filtration and HPLC yielded a few fractions that induced different effects when administered intraperitoneally in mice. One of these fractions, PF3, was chemically characterized as a cysteine-rich polypeptide of 8360 MW. Administered at 0.1 mg/kg, i.p., PF3 induced a progressive paralysis and death of mice within 30 minutes. Partial sequence analysis of PF3 revealed certain homologies with other spider toxins already described, particularly omega-AGAIIA (60%) fromAgelenopsis aperta. Pharmacological characterization carried out in superfused chopped rat striatal tissues preloaded with [³H]-Dopamine ([³H]-DA) showed that PF3 (0.1 g/ml) decreased the [³H]-DA release induced by 20 mM K⁺ or 100 M glutamate without changing the basal release. At 1 g/ml, PF3 inhibited 33% of the basal release of [³H]-DA; the transmitter release stimulated by K⁺ or by glutamate was reduced by respectively, 87% and 77% of corresponding control values. PF3 (0.1 g/ml) altered the doseresponse curves of glutamate (1 M–10mM), by reducing by 36% of its maximal effect. Naloxone (1 M) did not influence the effect of PF3. The results indicate that PF3 inhibits the [³H]-DA release induced by membrane depolarization or that mediated by NMDA glutamate receptors. These data suggest that the mechanism of action of PF3 may involve a blockade of Ca²⁺ channels as well as a direct effect on the exocytotic machinery.Financial support of FAPESP—Fundação de Amparo a Pesquisa do Estado de São Paulo.     

Phoneutria nigriventer venom: a cocktail of toxins that affect ion channels

1. We review the pharmacological actions of toxins present in the venom of the aggressive spider Phoneutria nigriventer.2. This venom is rich in toxins that affect ion channels and neurotransmitter release. Voltage-gated sodium, calcium, and potassium channels have been described as the main targets of these toxins.3. In addition to these classical actions Phoneutria toxins have also been shown to affect glutamate transporter.4. It is expected that molecular genetics in addition to biochemical, biophysical and pharmacological approaches will help to further define Phoneutria toxins and their mechanisms of action in the near future.     

An examination of the potential role of spider digestive proteases as a causative factor in spider bite necrosis

Tissue necrosis following spider bites is a widespread problem. In the continental United States, the brown recluse (Loxosceles reclusa), hobo spider (Tegenaria agrestis), garden spider (Argiope aurantia) and Chiracanthium species, among others, reportedly cause such lesions. The exact mechanism producing such lesions is controversial. There is evidence for both venom sphingomyelinase and spider digestive collagenases. We have examined the role of spider digestive proteases in spider bite necrosis. The digestive fluid of A. aurantia was assayed for its ability to cleave a variety of connective tissue proteins, including collagen. Having confirmed that the fluid has collagenases, the digestive fluid was injected into the skin of rabbits to observe whether it would cause necrotic lesions. It did not. The data do not support the suggestions that spider digestive collagenases have a primary role in spider bite necrosis.     

Forces in the spider orb web

Summary Pretensile forces were measured in individual threads of intact spider webs. In the orb web of Araneus diadematus forces decrease from mooring threads to frame threads and radii, a typical ratio being 1071. The smaller number of radii in the upper than in the lower half of the orb is paralleled by force ratios of 21 to 31. A similar difference between radii built first during web construction and radii added after completion of the frame underlines the importance of the former as part of the scaffolding. High tensions in the auxiliary spiral stabilize the radii in addition to providing a pathway for the spider when inserting the sticky spiral. Radial pretension (F) changes with spider mass (m). F/m is similar for different animals indicating an adaptation of radial forces to those resulting from spider mass. Several observations suggest tension control by the spider. When forced to anchor its web to thin flexible rods tension in the threads remains in the normal range. Tension values are similar in the webs of A. diadematus, Zygiella x-notata, Nuctenea umbratica, and Nephila clavipes indicating independence from details of web geometry. Only the mooring threads of Nephila show unusually large forces suggesting a narrower working range of tensions for the catching area than for the scaffolding.     

The roles of intracellular regions in the activation of voltage-dependent potassium channels

The involvement of the transmembrane regions S2, S3 and S4 in the activation of potassium channels by depolarization has been well clarified. However, a role of the intracellular regions in channel function is emerging. Here we review recent evidence for the roles of intracellular regions in the functioning of members of two families of channels. The Kv2.1 potassium channel, a member of the voltage activated Kv family, has long intracellular regions. By mutagenesis studies and expression in oocytes, we identify residues in both the N- and C-terminal regions that contribute to determining activation kinetics of this channel. It seems that the C-terminus wraps around the N-terminus and interacts with it functionally. The voltage-activated ether-a-go-go (eag) channels also have long intracellular regions. Despite considerable homology, eag1 and eag2 channels display different activation kinetics. By making chimeras between these channels and again expressing in oocytes, we show that residues in both the N-terminal region and the membrane-spanning region are involved in determining these differences in activation kinetics. The intracellular N- and C-terminal regions are likely to continue to prove fertile regions in future investigations into the functioning of ion channels.Presented at the Biophysical Society Meeting on Ion channels—from structure to disease held in May 2003, Rennes, France     

Lattice deformation and thermal stability of crystals in spider silk

The X-ray diffraction of dragline silks, produced by Nephila and Cyrtophora spiders, were measured by synchrotron radiation in their original states or in situ during stretching and heating. Nephila pilipes spiders construct a two-dimensional orb web that must be rebuilt in one or 2 days, but Cyrtophora spiders form a three-dimensional tent web that can exist for several weeks in a tropical forest. Diffraction patterns of N. pilipes and Cyrtophora draglines resemble each other. Crystals of two kinds are identified in these draglines; one is aligned parallel to the silk direction and another is less oriented. The less oriented crystal in Cyrtophora dragline is aligned better than that in N. pilipes dragline, which generates about three times stronger diffract intensity. Crystals in N. pilipes and C. moluccensis dragline silks have remarkable thermal stability. Equatorial reflections remain undiminished until 350 and 450 °C for N. pilipes and C. moluccensis, respectively. In contrast, the meridional reflections S and (0 0 2), which are parallel to the silk thread, disappear at a temperature less than 100 °C for C. moluccensis but remain for Nephila up to 100 °C. Meridional reflections S and (0 0 2) shift to a smaller angle during stretching, whereas equatorial reflections remain constant in a range 1.0–1.3 times the original length. The position of the S reflection shifts rapidly in the first 10% of elongation from the original length but remains constant during subsequent stretching, whereas the (0 0 2) reflection shifts rapidly during the first 5% elongation from the original length and continues to shift subsequently. In contrast, the features of N. pilipes dragline alter insignificantly during stretching. Examination of the composition of amino acids of the draglines of N. pilipes and C. moluccensis indicates that a dragline of N. pilipes contains more glycine, but much less alanine, than that of C. moluccensis.     

Inheritance of sex ratio in the Kanzawa spider mite,Tetranychus kanzawai Kishida

Population Ecology - The frequency distributions in sex ratios of offspring from 4 fieldTetranychus kanzawai populations were examined. No significant difference was observed between average sex...