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Academic literature on the topic 'Toxin'

Author: Grafiati

Published: 4 June 2021

Last updated: 9 June 2025

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Journal articles on the topic "Toxin"

1

McMillin, David E., Lycurgus L. Muldrow, and Shwanda J. Laggette. "Simultaneous detection of toxin A and toxin B genetic determinants of Clostridium difficile using the multiplex polymerase chain reaction." Canadian Journal of Microbiology 38, no. 1 (January 1, 1992): 81–83. http://dx.doi.org/10.1139/m92-013.

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A multiplex polymerase chain reaction was developed to simultaneously detect the presence of toxin A and toxin B genes of Clostridium difficile. A 1050-bp fragment of the toxin B gene and a 1217-bp fragment of the toxin A gene were amplified from 42 toxic strains of C. difficile; however, from 10 nontoxic strains the toxin gene fragments were not amplified; these data demonstrate that this multiplex polymerase chain reaction procedure can be used to differentiate between toxic and nontoxic strains. This sensitive and specific multiplex polymerase chain reaction for C. difficile toxins may prove to be a valuable diagnostic procedure. Key words: Clostridium difficile, polymerase chain reaction, bacterial toxins.

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Zhang, Yuchengmin, Hongchen Zhu, Tomohiro Takatani, and Osamu Arakawa. "Toxin Accumulation, Distribution, and Sources of Toxic Xanthid Crabs." Toxins 17, no. 5 (May 5, 2025): 228. https://doi.org/10.3390/toxins17050228.

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Several species of crabs from the Xanthidae family are recognized as dangerous marine organisms due to their potent neurotoxins, including paralytic shellfish toxin (PST), tetrodotoxin (TTX), and palytoxin (PLTX). However, the mechanisms of toxin accumulation and transport and the origin of these toxins in toxic xanthid crabs remain unknown. The identification of toxic crab species, their toxicity and toxin composition, and toxin profiles have been studied thus far. To date, more than ten species of xanthid crabs have been confirmed to possess toxins. Recently, several new studies on crabs, including the geographic distribution of toxin profiles and the ecological role of crabs, have been reported. Therefore, this review provides a summary of global research on toxic xanthid crabs, containing new findings and hypotheses on the toxification in and the origins of these crabs. Furthermore, the challenges and future perspectives in this field are also discussed.

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Qu, Jiangqi, Liping Shen, Meng Zhao, Wentong Li, Chengxia Jia, Hua Zhu, and Qingjing Zhang. "Determination of the Role of Microcystis aeruginosa in Toxin Generation Based on Phosphoproteomic Profiles." Toxins 10, no. 7 (July 23, 2018): 304. http://dx.doi.org/10.3390/toxins10070304.

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Microcystis aeruginosa is the most common species responsible for toxic cyanobacterial blooms and is considered a significant contributor to the production of cyanotoxins, particularly the potent liver toxins called microcystins. Numerous studies investigating Microcystis spp. blooms have revealed their deleterious effects in freshwater environments. However, the available knowledge regarding the global phosphoproteomics of M. aeruginosa and their regulatory roles in toxin generation is limited. In this study, we conducted comparative phosphoproteomic profiling of non-toxic and toxin-producing strains of M. aeruginosa. We identified 59 phosphorylation sites in 37 proteins in a non-toxic strain and 26 phosphorylation sites in 18 proteins in a toxin-producing strain. The analysis of protein phosphorylation abundances and functions in redox homeostasis, energy metabolism, light absorption and photosynthesis showed marked differences between the non-toxic and toxin-producing strains of M. aeruginosa, indicating that these processes are strongly related to toxin generation. Moreover, the protein-protein interaction results indicated that BJ0JVG8 can directly interact with the PemK-like toxin protein B0JQN8. Thus, the phosphorylation of B0JQN8 appears to be associated with the regulatory roles of toxins in physiological activity.

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Possani, L. D., B. M. Martin, I. Svendsen, G. S. Rode, and B. W. Erickson. "Scorpion toxins from Centruroides noxius and Tityus serrulatus. Primary structures and sequence comparison by metric analysis." Biochemical Journal 229, no. 3 (August 1, 1985): 739–50. http://dx.doi.org/10.1042/bj2290739.

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The complete primary structures of toxin II-14 from the Mexican scorpion Centruroides noxius Hoffmann and toxin gamma from the Brazilian scorpion Tityus serrulatus Lutz and Mello have been determined. Cleavage of toxin gamma after Met-6 with CNBr produced the 55-residue peptide 7-61, which maintained the four disulphide bonds but was not toxic to mice at a dose 3 times the lethal dose of native toxin gamma. Pairwise comparison by metric analysis of segment 1-50 of toxin gamma and the corresponding segments from two other South American scorpion toxins, five North American scorpion toxins, nine North African scorpion toxins and one Central Asian scorpion toxin showed that the three Brazilian toxins are intermediate between the North American and North African toxins. This result is consistent with the hypothesis that the South American and African continents were joined by a land connection in the distant past.

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Roderer, Daniel, and Stefan Raunser. "Tc Toxin Complexes: Assembly, Membrane Permeation, and Protein Translocation." Annual Review of Microbiology 73, no. 1 (September 8, 2019): 247–65. http://dx.doi.org/10.1146/annurev-micro-102215-095531.

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Tc toxin complexes are virulence factors of many bacteria, including insect and human pathogens. Tc toxins are composed of three subunits that act together to perforate the host membrane, similar to a syringe, and translocate toxic enzymes into the host cell. The reactions of the toxic enzymes lead to deterioration and ultimately death of the cell. We review recent high-resolution structural and functional data that explain the mechanism of action of this type of bacterial toxin at an unprecedented level of molecular detail. We focus on the steps that are necessary for toxin activation and membrane permeation. This is where the largest conformational transitions appear. Furthermore, we compare the architecture and function of Tc toxins with those of anthrax toxin and vertebrate teneurin.

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Archana, M. S. "Toxin yet not toxic: Botulinum toxin in dentistry." Saudi Dental Journal 28, no. 2 (April 2016): 63–69. http://dx.doi.org/10.1016/j.sdentj.2015.08.002.

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Blanco, Juan. "Accumulation of Dinophysis Toxins in Bivalve Molluscs." Toxins 10, no. 11 (November 2, 2018): 453. http://dx.doi.org/10.3390/toxins10110453.

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Several species of the dinoflagellate genus Dinophysis produce toxins that accumulate in bivalves when they feed on populations of these organisms. The accumulated toxins can lead to intoxication in consumers of the affected bivalves. The risk of intoxication depends on the amount and toxic power of accumulated toxins. In this review, current knowledge on the main processes involved in toxin accumulation were compiled, including the mechanisms and regulation of toxin acquisition, digestion, biotransformation, compartmentalization, and toxin depuration. Finally, accumulation kinetics, some models to describe it, and some implications were also considered.

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Goulard, Céline, Sophie Langrand, Elisabeth Carniel, and Sylvie Chauvaux. "The Yersinia pestis Chromosome Encodes Active Addiction Toxins." Journal of Bacteriology 192, no. 14 (May 14, 2010): 3669–77. http://dx.doi.org/10.1128/jb.00336-10.

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ABSTRACT Toxin-antitoxin (TA) loci consist of two genes in an operon, encoding a stable toxin and an unstable antitoxin. The expression of toxin leads to cell growth arrest and sometimes bacterial death, while the antitoxin prevents the cytotoxic activity of the toxin. In this study, we show that the chromosome of Yersinia pestis, the causative agent of plague, carries 10 putative TA modules and two solitary antitoxins that belong to five different TA families (HigBA, HicAB, RelEB, Phd/Doc, and MqsRA). Two of these toxin genes (higB2 and hicA1) could not be cloned in Escherichia coli unless they were coexpressed with their cognate antitoxin gene, indicating that they are highly toxic for this species. One of these toxin genes (higB2) could, however, be cloned directly and expressed in Y. pestis, where it was highly toxic, while the other one (hicA1) could not, probably because of its extreme toxicity. All eight other toxin genes were successfully cloned into the expression vector pBAD-TOPO. For five of them (higB1, higB3, higB5, hicA2, and tox), no toxic activity was detected in either E. coli or Y. pestis despite their overexpression. The three remaining toxin genes (relE1, higB4, and doc) were toxic for E. coli, and this toxic activity was abolished when the cognate antitoxin was coexpressed, showing that these three TA modules are functional in E. coli. Curiously, only one of these three toxins (RelE1) was active in Y. pestis. Cross-interaction between modules of the same family was observed but occurred only when the antitoxins were almost identical. Therefore, our study demonstrates that of the 10 predicted TA modules encoded by the Y. pestis chromosome, at least 5 are functional in E. coli and/or in Y. pestis. This is the first demonstration of active addiction toxins produced by the plague agent.

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Loh, Zhi Hung, Diane Ouwerkerk, Athol V. Klieve, Natasha L. Hungerford, and Mary T. Fletcher. "Toxin Degradation by Rumen Microorganisms: A Review." Toxins 12, no. 10 (October 20, 2020): 664. http://dx.doi.org/10.3390/toxins12100664.

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Animal feeds may contain exogenous compounds that can induce toxicity when ruminants ingest them. These toxins are secondary metabolites originating from various sources including plants, bacteria, algae and fungi. Animal feed toxins are responsible for various animal poisonings which negatively impact the livestock industry. Poisoning is more frequently reported in newly exposed, naïve ruminants while ‘experienced’ ruminants are observed to better tolerate toxin-contaminated feed. Ruminants can possess detoxification ability through rumen microorganisms with the rumen microbiome able to adapt to utilise toxic secondary metabolites. The ability of rumen microorganisms to metabolise these toxins has been used as a basis for the development of preventative probiotics to confer resistance against the poisoning to naïve ruminants. In this review, detoxification of various toxins, which include plant toxins, cyanobacteria toxins and plant-associated fungal mycotoxins, by rumen microorganisms is discussed. The review will include clinical studies of the animal poisoning caused by these toxins, the toxin mechanism of action, toxin degradation by rumen microorganisms, reported and hypothesised detoxification mechanisms and identified toxin metabolites with their toxicity compared to their parent toxin. This review highlights the commercial potential of rumen inoculum derived probiotics as viable means of improving ruminant health and production.

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Hanna, B. A. "Toxic shock syndrome toxin." JAMA: The Journal of the American Medical Association 254, no. 15 (October 18, 1985): 2062b—2062. http://dx.doi.org/10.1001/jama.254.15.2062b.

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Dissertations / Theses on the topic "Toxin"

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Javid-Khojasteh, Vahideh. "Toxic Shock Syndrome Toxin-1 : detection of the toxin, anti-toxin antibodies and producer organisms in a paediatric burns unit." Thesis, University of Salford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365993.

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Guttenberg, Gregor [Verfasser], and Manfred [Akademischer Betreuer] Jung. "Clostridiale Glukosylierende Toxine: Untersuchungen zur Autoprozessierung von Clostridium sordellii Letalem Toxin und Clostridium novyi alpha-Toxin sowie funktionelle Charakterisierung von Clostridium perfringens TpeL-Toxin." Freiburg : Universität, 2012. http://d-nb.info/1123467994/34.

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Maldonado-Arocho, Francisco J. "Characterization of host-pathogen interaction of two bacterial toxins anthrax edema toxin and Escherichia coli cytolethal distending toxin /." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1973060671&sid=4&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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Fernandes, da Costa Sérgio Paulo. "Molecular and structural characterisation of epsilon toxin and necrotic enteritis toxin B : two pore-forming toxins from Clostridium perfringens." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14608.

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Epsilon toxin (Etx) and necrotic enteritis toxin B (NetB) are two pore-forming toxins produced by C. perfringens. While Etx has been shown to be the key virulence factor for enterotoxemia in goats and sheep, NetB has been associated with the pathogenesis of avian necrotic enteritis (NE), a gastro-intestinal disease causing economic damage to the poultry industry worldwide. The crystal structure of Etx H149A (an Etx variant with 6x reduced toxicity relative to wild type toxin) was solved to 2.4 Å and showed that the H149A mutation in domain III does not affect organization of the receptor binding region in domain I. The Etx H149A structure also revealed a second putative glycan binding site in domain III. In addition, site-directed mutagenesis in domain I of Etx H149A affirmed the important role of tyrosine residues for toxin binding and demonstrated the capability of Etx H149A to be used as a platform for further receptor binding studies in the future. The crystal structure of the pore-form of NetB was solved to 3.9 Å and revealed high similarities to the Staphylococcus aureus α-hemolysin heptameric structure. However, in particular the region thought to interact with the target cell membrane showed some interesting divergence in amino acid composition. Site-directed mutagenesis within this domain significantly affected binding and toxicity of NetB to target cells. Mutagenesis within the β-sandwich domain of NetB revealed important amino acid residues for toxin oligomerisation and pore-formation. In order to test NetB toxoids as candidate vaccines, a NetB genetic toxoid and a formaldehyde NetB toxoid were used to immunise poultry in an in vivo NE disease model. Vaccination with any of the two antigens resulted in the induction of specific antibody responses against NetB and provided significant protection against disease.

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Hovey, Bianca T. "Cholera toxin and heat-labile enterotoxin : structural studies of assembly and design of active A-subunit constructs /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/9263.

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Edwards-Jones, Valerie. "Toxic shock syndrome toxin production in relation to burned patients." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244871.

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Kuk, Chiu Ying. "Anthrax Lethal Toxin Is a Tumor Hemorragic Toxin." Thesis, Van Andel Research Institute, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10973827.

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<p> Blood supply is crucial for tumor growth and metastasis. However, current anti-angiogenic therapy is not as effective as predicted, thus a better understanding of the tumor angiogenic process and new anti-angiogenic agent are urgently required. Anthrax lethal toxin (LeTx) has an anti-angiogenic effect on tumors. Tumors treated with LeTx are smaller, paler, and have lower mean vessel density compared to control treated tumors. Most interestingly, compared to current anti-angiogenic treatment, LeTx does not cause normalization of tumor vessels. Instead, tumors treated with LeTx have massive hemorrhages, pointing to a potential alternative mechanism to inhibit tumor angiogenesis. I hypothesize that instead of causing “normalization” of tumor vasculature, LeTx’s anti-angiogenic effects works in a manner similar to a hemorrhagic toxins. To test this hypothesis, I compared the effect of LeTx to snake venom metalloproteinase, a known hemorrhagic toxin, in tumor vasculature. Quantified by Nuance multispectral imaging system, both LeTx and SVMP caused an increase in tumor hemorrhage. Futher analysis of vasculature integrity using continued vessel length showed disruption of vessels by LeTx and SVMP. With these results, I conclude that the anti-angiogenic effects of LeTx are due to its hemorrhagic nature, and not due to normalization of tumor vasculature. Further understanding of LeTx mechanism can help design novel anti-angiogenic agent that compliments current therapy.</p><p>

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Pellino, Christine A. "Characterization of Shiga Toxin Potency and Assembly." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1418909563.

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Penha, Marcelo De Luca. "Detecção dos genes das toxinas alfa, beta e épsilon de Clostridium perfringens isolados a partir de amostras clínicas de bovinos pela reação em cadeia da polimerase." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/10/10134/tde-06072005-101119/.

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O Clostridium perfringens é um microrganismo anaeróbio que está presente no solo e no trato intestinal dos mamíferos. Provoca intoxicação alimentar nos seres humanos, doenças enterotoxêmicas nos animais domésticos e gangrena gasosa em ambos os grupos. O C. perfringens é classificado em cinco tipos (A, B, C, D e E) mediante a produção de quatro toxinas principais (alfa, beta, épsilon e iota). Neste trabalho foi possível padronizar a técnica de PCR para detectar a presença dos genes cpa, cpb e etx a partir de culturas de C. perfringens. A sensibilidade analítica da técnica de PCR a partir de culturas de C. perfringens foi de 2,27 ng/µL para o gene cpa, 22,7 pg/µL para o gene cpb e 22,7 pg/µL para o gene etx. A pesquisa dos genes cpa, cpb e etx partir de 35 amostras de C. perfringens isoladas de bovinos revelou que 16 (45,7%) eram do tipo A; 18 (51,4%) eram do tipo C e 1 (2,9%) era do tipo B. Não foi observada nenhuma amostra do tipo D. A metodologia de PCR revelou-se útil na tipificação de amostras de C. perfringens isoladas de bovinos, contribuindo para o diagnóstico dessa bacteriose neste país, eliminando as dificuldades de tipificação oriundas do alto custo e da indisponibilidade de anti-soros para a tipificação pela reação de soroneutralização e evitando a utilização de animais de laboratório.<br>Clostridium perfringens is an anaerobic micro-organism that is present in the soil and gastrointestinal tract of mammals. It causes food poisoning in humans, enterotoxemic diseases in domestic animals and gas gangrene in both. C. perfringens is classified into five types (A, B, C, D and E) according to the production of four major toxins (alpha, beta, epsilon and iota). In this trial was possible to standardize the PCR?s technique to detect cpa, cpb and etx genes from cultures of C. perfringens. PCR?s analythical sensibility was 2.27 ng/µL for cpa gene, 22.7 pg/µL for cpb gene and 22.7 pg/µL for etx gene. The research of cpa, cpb and etx genes from 35 samples of C. perfringens isolated from cattle reveals that 16 (45.7%) were classified as type A, 18 (51.4%) as type C and 1 (2.9%) as type B. No sample of type D was observed. PCR?s technique reveals to be usefull to typify samples of C. perfringens isolated from cattle, contributing to diagnose of this bacterial disease in this country and solving typifing problems represented by the high costs of the process and by the lack of antiserum that is required to typify the micro-organism by seroneutralization. PCR?s technique avoid the use of laboratory animals, too.

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Rosten, Patricia Melanie. "The role of toxic shock syndrome toxin-1 in the pathogenesis of toxic shock syndrome." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26527.

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Toxic shock syndrome toxin-1 (TSST-1), an exoprotein produced by some strains of Staphylococcus aureus, is implicated in the pathogenesis of menstrual TSS. However, its role in nonmenstrual TSS is less certain. In order to study the pathogenetic role of TSST-1 in TSS, three approaches were taken: a) to develop an ELISA for detection of TSST-1 in biologic fluids in order to verify TSST-1 production in vivo in TSS patients, b) to quantitate TSST-1 specific antibodies in the serum of TSS patients and controls to determine whether such antibodies are protective, and c) to attempt to identify other staphylococcal products which may be implicated in some forms of TSS. A sensitive and specific noncompetitive enzyme-linked immunosorbent assay (ELISA) capable of detecting TSST-1 at concentrations from 0.5 to 16 ng/ml was developed. This assay did not detect other staphylococcal enterotoxins including A, B, C₁, C₂, C₃, D and E. Possible interference by protein A was readily eliminated by pretreatment of test samples with 10% nonimmune rabbit serum. The assay was adapted for rapid screening of TSST-1 production by S. aureus isolates in culture supernatants in vitro, and for the detection of TSST-1 in vaginal washings and urine of TSS patients and healthy controls in vivo. All 35 S. aureus isolates confirmed to be TSST-1 positive by Ouchterlony immunodiffusion, and 59 of 60 isolates confirmed to be TSST-1 negative, gave concordant results by ELISA. Interestingly, toxigenic S. aureus strains isolated from TSS patients quantitatively produced significantly more toxin in vitro compared to toxigenic control strains (p<0.05, Mann-Whitney rank sum test). TSST-1 could be detected by ELISA in 3 of 4 vaginal washings collected within 3 days of hospitalization from 3 women with acute menstrual TSS, compared to 0 of 17 washings from 9 TSS women collected greater than 3 days after hospitalization (p=0.003, Fisher's exact test) and 1 of 15 washings from 14 healthy control women (p=0.016). TSST-1 was not detected in the urine of 4 acute TSS patients, 2 convalescent TSS patients or in 3 control urine tested. A sensitive and reproducible ELISA was also developed for the quantitation of TSST-1 specific IgG in serum. Anti-TSST-1 was assessed in acute and convalescent sera from 16 nonmenstrual (9 female, 7 male) and 14 menstrual TSS patients, and from 87 healthy women and 66 healthy men as controls. Quantitative levels of anti-TSST-1 in the study groups were calculated as the percent of standard activity (POSA) relative to a medium titre reference serum standard. ELISA titers in acute sera from menstrual TSS (26.2 ± 5.2, mean POSA ± S.E.M.), but not nonmenstrual TSS women (71.8 ± 18.6), were significantly lower than in healthy controls (78.9 ± 7.3) (p<0.01, Mam-Whitney test). Titers from menstrual TSS patients remained low (25.2 ± 10.7) even during late convalescence (mean duration 20 months after illness onset), compared to healthy female controls (p<0.05). Acute titers in males with TSS (37.0 ± 15.6) were also significantly lower than those in control men (114.6 + 11.0) (p<0.05). An inverse relationship of recovery of toxigenic S. aureus and anti-TSST-1 titers in acute sera of TSS patients was observed. Interestingly, antibody titers in control men were significantly higher than in control women (p<0.001). No age-dependent effects or interactive effects of age and sex on ELISA titers were observed. To enable immunoblot analyses, TSST-1 was produced and partially purified using column chromatography techniques. Percent recovery of TSST-1 from culture supernatant through to the final procedure was approximately 15.5%. The relative purity of TSST-1 (TSST-l/total protein, w/w) was increased from 0.21% in culture supernatants to 94.4% in the final product. Ouchterlony immunoprecipitation against reference rabbit antitoxin demonstrated identity with reference TSST-1 as well as with TSST-1 prepared in other laboratories. Physical characterization demonstrated a molecular weight of 24 kd and a pi of 7.0. Using pooled normal human serum as a first antibody probe, several bands in addition to the 24 kd TSST-1 band were visualized by immunoblot against our partially purified toxin as well as similar preparations obtained from other investigators. To determine whether any of the additional bands might be implicated in TSS, acute and convalescent sera from TSS patients were used to probe for immunoreactive bands in our partially purified TSST-1 as well as a commercially obtained preparation. Seroconversion was demonstrated to the 24 kd TSST-1 protein in 7 of 10 TSS patients from whom toxigenic S. aureus was isolated. In addition, seroconversion was noted to a 49 kd band in 4 patients, to a 21 kd band in 3 patients, to a 28 kd band in 1 patient and to a 32 kd band in 2 patients. In conclusion: 1) the ability to measure TSST-1 in biologic fluids lends stronger support for the role of TSST-1 in menstrual TSS patients; 2) the serologic data support the etiologic role of TSST-1 in menstrual TSS and in nonmenstrual TSS patients from whom toxigenic S. aureus could be cultured, but not for nonmenstrual TSS women from whom toxigenic S. aureus was not isolated; 3) immunoblotting results with acute and convalescent sera from TSS and control patients, not only add further support to the role of TSST-1 in patients from whom toxigenic S. aureus could be isolated, but also indicate that there may be several other staphylococcal products implicated in TSS, particularly in whom antibody to TSST-1 pre-existed in acute sera. The nonresponsiveness or lack of seroconversion to TSST-1 in some patients could suggest either: a) TSST-1 was not the etiologic agent for such patients; b) TSST-1 was the etiologic agent, but the exposure was sufficient for an immune response (similar to tetanus), or; c) some immunologic defect may be present. Future studies are required to clarify these possibilities.<br>Science, Faculty of<br>Microbiology and Immunology, Department of<br>Graduate

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Books on the topic "Toxin"

1

L, Simpson Lance, ed. Botulinum neurotoxin and tetanus toxin. San Diego: Academic Press, 1989.

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Robin, Cook. Toxin. New York: Putnam, 1998.

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Robin, Cook. Toxin. New York: Berkley Books, 1999.

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Robin, Cook. Toxin. London: BCA, 1998.

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Robin, Cook. Toxin. New York: Berkley Books, 1999.

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Robin, Cook. Toxin. Thorndike, Me: G.K. Hall, 1998.

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F, Brin Mitchell, Jankovic Joseph, and Hallett Mark, eds. Scientific and therapeutic aspects of botulinum toxic. Philadelphia: Lippincott William & Wilkins, 2002.

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Ronald, Sekura, Moss Joel, Vaughan Martha 1926-, National Institute of Child Health and Human Development (U.S.), National Heart, Lung, and Blood Institute., and Pertussis Toxin Conference (1984 : National Institutes of Health), eds. Pertussis toxin. Orlando: Academic Press, 1985.

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NIH Consensus Development Conference on Clinical Use of Botulinum Toxin (1990 Bethesda, Md.). Botulinum toxin. Bethesda, Md: U.S. Dept. of Health and Human Services, Public Health Service, National Institutes of Health, Office of Medical Applications of Research, 1990.

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B, Sommer, and Sattler G. 1955-, eds. Botulinum toxin in aesthetic medicine. Berlin: Blackwell-Wissenschaft-Verlag, 2001.

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Book chapters on the topic "Toxin"

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Bährle-Rapp, Marina. "Toxin." In Springer Lexikon Kosmetik und Körperpflege, 561. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_10623.

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Gressner, A. M., and O. A. Gressner. "Toxin." In Springer Reference Medizin, 2326–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2019. http://dx.doi.org/10.1007/978-3-662-48986-4_3072.

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Gressner, A. M., and O. A. Gressner. "Toxin." In Lexikon der Medizinischen Laboratoriumsdiagnostik, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49054-9_3072-1.

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Gooch, Jan W. "Toxin." In Encyclopedic Dictionary of Polymers, 928. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_14984.

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Ohlendorf, Douglas H., David T. Mitchell, G. Sridhar Prasad, R. Radhakrishnan, Cathleen A. Earhart, and Patrick M. Schlievert. "Structure of Toxic Shock Syndrome Toxin-1." In Protein Toxin Structure, 217–29. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-662-22352-9_11.

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Oeltmann, Thomas N., and Ronald G. Wiley. "Hormone, lectin and toxin-toxin conjugates." In Immunotoxins, 281–95. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-1083-9_16.

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Rzany, Berthold, and Alexander Nast. "Botulinum Toxin." In Evidence-Based Procedural Dermatology, 333–42. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-0-387-09424-3_19.

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Yarwood, Jeremy M., and Patrick M. Schlievert. "Toxin Production." In Infectious Agents and Pathogenesis, 93–115. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/0-306-46848-4_6.

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el Bayâ, Ali, Ruth Linnemann, Lars von Olleschik-Elbheim, and M. Alexander Schmidt. "Pertussis Toxin." In Advances in Experimental Medicine and Biology, 83–86. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4419-8632-0_9.

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Hexsel, Doris M., Mariana Soirefmann, and Camile L. Hexsel. "Botulinum Toxin." In Dermatologic Surgery, 253–58. Oxford, UK: Wiley-Blackwell, 2012. http://dx.doi.org/10.1002/9781118412633.ch34.

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Conference papers on the topic "Toxin"

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Merchant, Fatima A., and Mehmet Toner. "Spatial and Dynamic Characterization of the Interaction of Staphylococcus Aureus Alpha-Toxin With Cell Membranes." In ASME 1997 International Mechanical Engineering Congress and Exposition, 3–8. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1305.

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Abstract Genetically engineered pore-forming proteins such as the H5 mutant of the staphylococcal aureus α-toxin, have been specially designed to achieve controlled and reversible plasma membrane permeabilization. Hence, quantitative information regarding the dynamics of poration is critical for designing applications employing α-toxins for the permeabilization of cell membranes. We have employed immunofluorescence imaging techniques in conjunction with viability assays to elucidate the spatial and temporal interactions of α-toxin with living cells. This information would aid in the design and development of better permeabilization protocols that effectively utilize the toxin to achieve efficient poration of a large number of cells.

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Dichtelmuller, H., and W. Stephan. "IN VIVO AND IN VITRO NEUTRALIZATION OF BACTERIAL TOXINES BY IGM ENRICHED AND CONVENTIONAL I. V. IMMUNOGLOBULINS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644255.

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Severe septic phenomena are caused bybacterial toxins. We therefore investigated the neutralization of toxins derived from Staphylococcus aureus and Pseudcmonas aeruginosa by different i.v. irtmunoglobulin preparations using hemolysis inhibition tests and mouse protection tests. The efficacy of conventional i.v. immunoglobulin containing preparations were compared with an IgM enriched i.v. immunoglobulin (Pentaglobin).For hemolysis inhibition tests sterile filtered supernatant of Staphylococcusaureus was prepared and given to human erythrocytes. When IgM enriched immunoglobulin was added, toxin depended hemolysis was inhibited. By addition of three different i.v. immunoglobulin preparationsno inhibition of hemolysis was observed. In order to confirm these results in vivo, mice were exposed to the toxic supernatant of Staphylococcus aureus intraperitoneally and treated with i.v. immunoglobulins (3.1 mg/animal) 30 min after toxin exposure. Significant protection of toxin exposed animals was achieved by IgM enriched i.v. immunoglobulin (92 % protection) but not by conventional i.v. immunoglobulin (17 % protection). Similar results were obtained when mice were exposed to toxic supernatant of Pseudcmonas aeruginosa instead of Staphylococcus aureus. We therefore conclude, that IgM is essential for neutralization of bacterial toxins and IgM enriched i.v. immunoglobulins are more effective in therapy of severe septic phenomena, compared to conventional i.v. immunoglobulins.

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Taylor, Graham, Donald Leo, and Andy Sarles. "Detection of Botulinum Neurotoxin/A Insertion Using an Encapsulated Interface Bilayer." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-8101.

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Many signaling mechanisms in living cells occur at biological boundaries via cell surface receptors and membrane proteins embedded in lipid bilayers. The coordination of actions of sensory and motor neurons in the nervous system represents one example of many that heavily depends on lipid membrane bound receptor mediated signaling. As a result, chemical and biological toxins that disrupt these neural signals can have severe physiological effects, including paralysis and death. Botulinum neurotoxin Type A (BoNT/A) is a proteolytic toxin that inserts through vesicle membranes and cleaves membrane receptors involved with synaptic acetylcholine uptake and nervous system signal conduction. In this work, we investigate the use of a Bioinspired liquid-supported interface bilayer for studying the insertion of BoNT/A toxin molecules into synthetic lipid bilayers. DPhPC lipid bilayers are formed using the regulated attachment method (RAM), as developed by Sarles and Leo, and we perform current measurements on membranes exposed to BoNT/A toxin to characterize activity of toxin interacting with the synthetic bilayer. Control tests without toxin present are also presented. The results of these tests show an increase in the magnitude of current through the bilayer when the toxin is included. We interpret these initial results to mean that incorporation of BoNT/A toxin at a high concentration in an interface bilayer increases the permeability of the membrane as a result of toxin molecules spanning the thickness of the bilayer.

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Kelly, Dan, Xuedong Song, Daniel K. Frayer, Sergio B. Mendes, Nasser Peyghambarian, Basil I. Swanson, and Karen M. Grace. "Integrated optical toxin sensor." In Photonics East '99, edited by Mahmoud Fallahi and Basil I. Swanson. SPIE, 1999. http://dx.doi.org/10.1117/12.372899.

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Menking, Darrell E., Jonathon M. Heitz, Nabil A. Anis, and Roy G. Thompson. "Antibody-based bacterial toxin detection." In Optical Tools for Manufacturing and Advanced Automation, edited by Robert A. Lieberman. SPIE, 1994. http://dx.doi.org/10.1117/12.170668.

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Bachran, Christopher, Suzanne Abdelazim, Radka Hasikova, Shihui Liu, and Stephen H. Leppla. "Abstract 5601: Efficient tumor therapy by anthrax toxin fusion proteins that contain cytolethal distending toxin B." In Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC. American Association for Cancer Research, 2013. http://dx.doi.org/10.1158/1538-7445.am2013-5601.

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Ghosh, H., and C. RoyChaudhuri. "Nanocrystalline Porous silicon for sensitive toxin detection." In 2012 Sixth International Conference on Sensing Technology (ICST 2012). IEEE, 2012. http://dx.doi.org/10.1109/icsenst.2012.6461765.

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Fan, Z. Hugh, Q. Mei, R. Khnouf, and S. Jin. "Microfluidic protein synthesis array for toxin detection." In TRANSDUCERS 2009 - 2009 International Solid-State Sensors, Actuators and Microsystems Conference. IEEE, 2009. http://dx.doi.org/10.1109/sensor.2009.5285971.

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Couture, O., M. Tanter, E. Dransart, S. Dehay, and L. Johannes. "Targeting microbubbles with Shiga-Toxin B-subunit." In 2009 IEEE International Ultrasonics Symposium. IEEE, 2009. http://dx.doi.org/10.1109/ultsym.2009.5441692.

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Wittendorp, Paul, Catarina Moreirinha, Mariana Raposo, S. R. Maria Teresa Gomes, Michal Melnik, Alisa Rudnitskaya, and Froydis Sved Skottvoll. "Microfluidic electronic tongue for marine toxin detection." In 2024 IEEE International Symposium on Olfaction and Electronic Nose (ISOEN). IEEE, 2024. http://dx.doi.org/10.1109/isoen61239.2024.10556210.

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Reports on the topic "Toxin"

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Gurevitz, Michael, Michael E. Adams, Boaz Shaanan, Oren Froy, Dalia Gordon, Daewoo Lee, and Yong Zhao. Interacting Domains of Anti-Insect Scorpion Toxins and their Sodium Channel Binding Sites: Structure, Cooperative Interactions with Agrochemicals, and Application. United States Department of Agriculture, December 2001. http://dx.doi.org/10.32747/2001.7585190.bard.

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Integrated pest management in modern crop protection may combine chemical and biological insecticides, particularly due to the risks to the environment and livestock arising from the massive use of non-selective chemicals. Thus, there is a need for safer alternatives, which target insects more specifically. Scorpions produce anti-insect selective polypeptide toxins that are biodegradable and non-toxic to warm-blooded animals. Therefore, integration of these substances into insect pest control strategies is of major importance. Moreover, clarification of the molecular basis of this selectivity may provide valuable information pertinent to their receptor sites and to the future design of peptidomimetic anti-insect specific substances. These toxins may also be important for reducing the current overuse of chemical insecticides if they produce a synergistic effect with conventional pesticides. Based on these considerations, our major objectives were: 1) To elucidate the three-dimensional structure and toxic-site of scorpion excitatory, "depressant, and anti-insect alpha toxins. 2) To obtain an initial view to the sodium channel recognition sites of the above toxins by generating peptide decoys through a phage display system. 3) To investigate the synergism between toxins and chemical insecticides. Our approach was to develop a suitable expression system for toxin production in a recombinant form and for elucidation of toxin bioactive sites via mutagenesis. In parallel, the mode of action and synergistic effects of scorpion insecticidal toxins with pyrethroids were studied at the sodium channel level using electrophysiological methods. Objective 1 was achieved for the alpha toxin, LqhaIT Zilberberg et al., 1996, 1997; Tugarinov et al., 1997; Froy et al., 2002), and the excitatory toxin, Bj-xtrIT (Oren et al., 1998; Froy et al., 1999; unpublished data). The bioactive surface of the depressant toxin, LqhIT2, has been clarified and a crystal of the toxin is now being analyzed (unpublished). Objective 2 was not successful thus far as no phages that recognize the toxins were obtained. We therefore initiated recently an alternative approach, which is introduction of mutations into recombinant channels and creation of channel chimeras. Objective 3 was undertaken at Riverside and the results demonstrated synergism between LqhaIT or AaIT and pyrethroids (Lee et al., 2002). Furthermore, negative cross-resistance between pyrethroids and scorpion toxins (LqhaIT and AaIT) was demonstrated at the molecular level. Although our study did not yield a product, it paves the way for future design of selective pesticides by capitalizing on the natural competence of scorpion toxins to distinguish between sodium channels of insects and vertebrates. We also show that future application of anti-insect toxins may enable to decrease the amounts of chemical pesticides due to their synergism.

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Mevarech, Moshe, Jeremy Bruenn, and Yigal Koltin. Virus Encoded Toxin of the Corn Smut Ustilago Maydis - Isolation of Receptors and Mapping Functional Domains. United States Department of Agriculture, September 1995. http://dx.doi.org/10.32747/1995.7613022.bard.

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Ustilago maydis is a fungal pathogen of maize. Some strains of U. maydis encode secreted polypeptide toxins capable of killing other susceptible strains of U. maydis. Resistance to the toxins is conferred by recessive nuclear genes. The toxins are encoded by genomic segments of resident double-strande RNA viruses. The best characterized toxin, KP6, is composed of two polypeptides, a and b, which are not covalently linked. It is encoded by P6M2 dsRNA, which has been cloned, sequenced and expressed in a variety of systems. In this study we have shown that the toxin acts on the membranes of sensitive cells and that both polypeptides are required for toxin activity. The toxin has been shown to function by creating new pores in the cell membrane and disrupting ion fluxes. The experiments performed on artificial phospholipid bilayers indicated that KP6 forms large voltage-independent, cation-selective channels. Experiments leading to the resolution of structure-function relationship of the toxin by in vitro analysis have been initiated. During the course of this research the collaboration also yielded X-ray diffracion data of the crystallized a polypeptide. The effect of the toxin on the pathogen has been shown to be receptor-mediated. A potential receptor protein, identified in membrane fractions of sensitive cells, was subjected to tryptic hydrolysis followed by amino-acid analysis. The peptides obtained were used to isolate a cDNA fragment by reverse PCR, which showed 30% sequence homology to the human HLA protein. Analysis of other toxins secreted by U. maydis, KP1 and KP4, have demonstrated that, unlike KP6, they are composed of a single polypeptide. Finally, KP6 has been expressed in transgenic tobacco plants, indicating that accurate processing by Kex2p-like activity occurs in plants as well. Using tobacco as a model system, we determined that active antifungal toxins can be synthesized and targeted to the outside of transgenic plant cells. If this methodology can be applied to other agronomically crop species, then U. maydis toxins may provide a novel means for biological control of pathogenic fungi.

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Gurevitz, Michael, Michael Adams, and Eliahu Zlotkin. Insect Specific Alpha Neurotoxins from Scorpion Venoms: Mode of Action and Structure-Function Relationships. United States Department of Agriculture, June 1996. http://dx.doi.org/10.32747/1996.7613029.bard.

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This study was motivated by the need to develop new means and approaches to the design of future, environmentally-safe, insecticides. Utilization of anti-insect selective toxins from scorpion venoms and clarification of the molecular basis for their specificity, are a major focus in this project and may have an applicative value. Our study concentrated on the highly insecticidal toxin, LqhaIT, and was devoted to: (I) Characterization of the neuropharmacological and electrophysiological features of this toxin. (II) Establishment of a genetic system for studying structure/activity relationships of the toxin. (III) Analysis of the insecticidal efficacy of an entomopathogenic baculovirus engineered and expressing LqhaIT. The results obtained in this project suggest that: 1) The receptor binding site of LqhaIT on insect sodium channels differs most likely from its analogous receptor site 3 on vertebrate sodium channels. 2) The effects of LqhaIT are presynaptic. Hyperexcitation at the neuromuscular results from dramatic slowing of sodium channel inactivation and enhanced peak sodium currents causes by LqhaIT. 3) The putative toxic surface of LqhaIT involves aromatic and charged amino acid residues located around the C-terminal region and five-residue-turn of the toxin (unpublished). 4) The anti-insect/anti-mammalian toxicity ratio can be altered by site-directed mutagenesis (publication 8). This effect was partly shown at the level of sodium channel function. 5) The insecticidal efficacy of AcNPV baculovirus increased to a great extent when infection was accompanied by expression of LqhaIT (publication 5).

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Wisniewski, Michael, Samir Droby, John Norelli, Dov Prusky, and Vera Hershkovitz. Genetic and transcriptomic analysis of postharvest decay resistance in Malus sieversii and the identification of pathogenicity effectors in Penicillium expansum. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597928.bard.

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Use of Lqh2 mutants (produced at TAU) and rNav1.2a mutants (produced at the US side) for identifying receptor site-3: Based on the fact that binding of scorpion alpha-toxins is voltage-dependent, which suggests toxin binding at the mobile voltage-sensing region, we analyzed which of the toxin bioactive domains (Core-domain or NC-domain) interacts with the DIV Gating-module of rNav1.2a. This analysis was based on the assumption that the dissociation of toxin mutants upon depolarization would vary from that of the unmodified toxin should the substitutions affect a site of interaction with the channel Gating-module. Using a series of toxin mutants (mutations at both domains) and two channel mutants that were shown to reduce the sensitivity to scorpion alpha-toxins, and by comparison of depolarization-driven dissociation of Lqh2 derivatives off their binding site at rNav1.2a mutant channels we found that the toxin Core-domain interacts with the Gating-module of DIV. Details of the experiments and results appear in Guret al (2011). Mapping receptor site 3 at Nav1.2a by extensive channel mutagenesis (Seattle): Since previous studies with photoaffinity labeling and antibody mapping implicated domains I and IV in scorpion alpha-toxin binding, Nav1.2 channel mutants containing substitutions at these extracellular regions were expressed and tested for receptor function by whole-cell voltage clamp. Of a large number of channel mutants, T1560A, F1610A, and E1613A in domain IV had ~5.9-, ~10.7-, and ~3.9-fold lower affinities for the scorpion toxin Lqh2, respectively, and mutant E1613R had 73-fold lower affinity. Toxin dissociation was accelerated by depolarization for both wild-type and mutants, and the rates of dissociation were also increased by mutations T1560A, F1610A and E1613A. In contrast, association rates for these three mutant channels at negative membrane potentials were not significantly changed and were not voltage-dependent. These results indicated that Thr1560 in the S1-S2 loop, Phe1610 in the S3 segment, and Glu1613 in the S3-S4 loop in domain IV participate in toxin binding. T393A in the SS2-S6 loop in domain I also showed a ~3.4-fold lower affinity for Lqh2, indicating that this extracellular loop may form a secondary component of the toxin binding site. Analysis with the Rosetta-Membrane algorithm revealed a three-dimensional model of Lqh2 binding to the voltage sensor in a resting state. In this model, amino acid residues in an extracellular cleft formed by the S1-S2 and S3-S4 loops in domain IV that are important for toxin binding interact with amino acid residues on two faces of the wedge-shaped Lqh2 molecule that are important for toxin action. The conserved gating charges in the S4 transmembrane segment are in an inward position and likely form ion pairs with negatively charged amino acid residues in the S2 and S3 segments (Wang et al 2011; Gurevitz 2012; Gurevitzet al 2013).

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Gordon, Dalia, Ke Dong, and Michael Gurevitz. Unexpected Specificity of a Sea Anemone Small Toxin for Insect Na-channels and its Synergic Effects with Various Insecticidal Ligands: A New Model to Mimic. United States Department of Agriculture, November 2010. http://dx.doi.org/10.32747/2010.7697114.bard.

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Motivated by the high risks to the environment and human health imposed by the current overuse of chemical insecticides we offer an alternative approach for the design of highly active insect-selective compounds that will be based on the ability of natural toxins to differentiate between insect and mammalian targets. We wish to unravel the interacting surfaces of insect selective toxins with their receptor sites on voltage-gated sodium channels. In this proposal we put forward two recent observations that may expedite the development of a new generation of insect killers that mimic the highly selective insecticidal toxins: (i) A small (27aa) highly insecticidal sea anemone toxin, Av3, whose toxicity to mammals is negligible; (ii) The prominent positive cooperativity between distinct channel ligands, such as the strong enhancement of pyrethroids effects by anti-insect selective scorpion depressant toxins. We possess a repertoire of insecticidal toxins and sodium channel subtypes all available in recombinant form for mutagenesis followed by analysis of various pharmacological, electrophysiological, and structural methods. Our recent success to express Av3 provides for the first time a selective toxin for receptor site-3 on insect sodium channels. In parallel, our recent success to determine the structures and bioactive surfaces of insecticidal site-3 and site-4 toxins establishes a suitable system for elucidation of toxin-receptor interacting faces. This is corroborated by our recent identification of channel residues involved with these two receptor sites. Our specific aims in this proposal are to (i) Determine the bioactive surface of Av3 toward insect Na-channels; (ii) Identify channel residues involved in binding or activity of the insecticidal toxins Av3 and LqhaIT, which differ substantially in their potency on mammals; (iii) Illuminate channel residues involved in recognition by the anti-insect depressant toxins; (iv) Determine the face of interaction of both site-3 (Av3) and site-4 (LqhIT2) toxins with insect sodium channels using thermodynamic mutant cycle analysis; and, (v) Examine whether Av3, LqhIT2, pyrethroids, and indoxacarb (belongs to a new generation of insecticides), enhance allosterically the action of one another on the fruit fly and cockroach paraNa-channels and on their kdr and super-kdr mutants. This research establishes the grounds for rational design of novel anti-insect peptidomimetics with minimal impact on human health, and offers a new approach in insect pest control, whereby a combination of allosterically interacting compounds increases insecticidal action and reduces risks of resistance buildup.

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Gurevitz, Michael, Michael E. Adams, and Boaz Shaanan. Structural Elements and Neuropharmacological Features Involved in the Insecticidal Properties of an Alpha Scorpion Neurotoxin: A Multidisciplinary Approach. United States Department of Agriculture, August 1995. http://dx.doi.org/10.32747/1995.7573061.bard.

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Integrated pest management in modern crop protection requires the use of chemical or biological insecticides in many instances. Nontheless, the use non-selective chemical insecticides poses risks to the environment and livestock and consequently urgent need exists for safer alternatives, which target insects more specifically. Scorpions produce anti-insect selective polypeptide toxins that are biodegradable and not toxic to wam-blooded animals. Therefore, mobilization of these substances into insect pest targets is of major interest. Moreover, clarification of the molecular basis of this selectivity may provide valuable information pertinent to their receptor sites and to the future design of peptidomimetic anti-insect specific substances. These toxins may also be important for reducing the current overuse of chamical insecticides provided they have a synergistic effect with conventional pesticides. All of these objectives were addressed in this research. A direct approach for plant protection was the mobilization of toxins into target pests using baculoviral vectors. The other approach was to develop a suitable system enabling the elucidation of the toxin bioactive site, which would enable design of insecticidal peptidomimetics. In parallel, the mode of action and synergistic effects of scorpion insecticidal toxins, were studied at the sodium channel receptor site. All the above approaches show great promise and clearly indicate that scorpion insecticidal toxins may provide powerful means in insect pest control.

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Trammel, Harold L. Development of a Toxin Knowledge System. Fort Belvoir, VA: Defense Technical Information Center, November 1990. http://dx.doi.org/10.21236/adb152646.

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Leppla, Stephen H. Production and Purification of Anthrax Toxin. Fort Belvoir, VA: Defense Technical Information Center, May 1986. http://dx.doi.org/10.21236/ada170131.

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Iandolo, John J., and Stephen K. Chapes. Anti-Idiotype Probes for Toxin Detection. Fort Belvoir, VA: Defense Technical Information Center, September 1991. http://dx.doi.org/10.21236/ada242099.

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Gurevitz, Michael, William A. Catterall, and Dalia Gordon. Learning from Nature How to Design Anti-insect Selective Pesticides - Clarification of the Interacting Face between Insecticidal Toxins and their Na-channel Receptors. United States Department of Agriculture, January 2010. http://dx.doi.org/10.32747/2010.7697101.bard.

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Structural details on the interacting faces of toxins and sodium channels (Navs), and particularly identification of elements that confer specificity for insects, are difficult to approach and require suitable experimental systems. Therefore, natural toxins capable of differential recognition of insect and mammalian Navs are valuable leads for design of selective compounds in insect control. We have characterized several scorpion toxins that vary in preference for insect and mammalian Navs, and identified residues important for their action. However, despite many efforts worldwide, only little is known about the receptor sites of these toxins, and particularly on differences between these sites on insect and mammalian Navs. Another problem arises from the massive overuse of chemical insecticides, which increases resistance buildup among various insect pests. A possible solution to this problem is to combine different insecticidal compounds, especially those that provide synergic effects. Our recent finding that combinations of insecticidal receptor site-3 toxins (sea anemone and scorpion alpha) with scorpion beta toxins or their truncated derivatives are synergic in toxicity to insects is therefore timely and strongly supports this approach. Our ability to produce toxins and various Navs in recombinant forms, enable thorough analysis and structural manipulations of both toxins and receptors. On this basis we propose to (1) restrict by mutagenesis the activity of insecticidal scorpion -toxins and sea anemone toxins to insects, and clarify the molecular basis of their synergic toxicity with antiinsect selective -toxins; (2) identify Nav elements that interact with scorpion alpha and sea anemone toxins and those that determine toxin selectivity to insects; (3) determine toxin-channel pairwise side-chain interactions by thermodynamic mutant cycle analysis using our large collection of mutant -toxins and Nav mutants identified in aim 2; (4) clarify the mode of interaction of truncated -toxins with insect Navs, and elucidate how they enhance the activity of insecticidal site-3 toxins. This research may lead to rational design of novel anti-insect peptidomimetics with minimal impact on human health and the environment, and will establish the grounds for a new strategy in insect pest control, whereby a combination of allosterically interacting compounds increase insecticidal action and reduce risks of resistance buildup.

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