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Insect toxin

Hamid S Kachel, Steven D Buckingham, David B Sattelle
Insect toxins comprise a diverse array of chemicals ranging from small molecules, polyamines and peptide toxins. Many target nervous system and neuromuscular ion channels and so rapidly affect the behaviour of animals to which the toxin is applied or injected. Other modes of action have also been identified. Wasps, bees, flies, beetles and ants generate a rich arsenal of channel-active toxins, some of which offer selective pharmacological probes that target particular ion channels, while others act on more than one type of channel...
December 2018: Current Opinion in Insect Science
Hong Zhang, Meiting Zhao, Yiran Liu, Zhongshi Zhou, Jianying Guo
Cytochrome P450 monooxygenases (P450s) are a large class of enzymes that play essential roles in metabolic processes such as hormone synthesis and the catabolism of toxins and other chemicals in insects. In the present study, we identified 82 P450 genes using comprehensive RNA sequencing in the flea beetle Agasicles hygrophila, and all of the sequences were validated by cloning and sequencing. Phylogenetic analysis showed that the P450 genes in A. hygrophila fell into the mitochondrial clan, CYP2 clan, CYP3 clan and CYP4 clan and were classified into 20 families and 48 subfamilies...
December 14, 2018: Scientific Reports
Sílvia de Oliveira Dorta, Juliana Balbinotte, Rose Monnerat, João Roberto Spotti Lopes, Tatiane da Cunha, Odimar Zanuzo Zanardi, Marcelo Pedreira de Miranda, Marcos Antonio Machado, Juliana de Freitas-Astúa
Bacillus thuringiensis (Bt) toxins are effective in controlling insect pests either through the spraying of products or when expressed in transgenic crops. The discovery of endophytic Bt strains opened new perspectives for studies aimed at the control of sap-sucking insects, such as the Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae), a vector of 'Candidatus Liberibacter spp.', associated with citrus huanglongbing (HLB). In this study, translocation of endophytic Bt strains in citrus seedlings inoculated with Bt suspension delivered by soil-drench, and their systemic pathogenicity to D...
December 10, 2018: Insect Science
Jiahe Wu, Yingchuan Tian
An optimized vip3A gene, designated as vip3A*, was chemically synthesized, and a chloroplast transit peptide sequence of thi1 gene was attached to its 5' end to produce the tvip3A*. vip3A* and tvip3A* genes were transformed into Gossypium hirsutum cv. Zhongmiansuo35 mediated by Agrobacterium tumefaciens. Four independent transgenic T1 lines with single-copy insertions and comparable phenotypes (CTV1 and CTV2 for tvip3A*, and CV1 and CV2 for vip3A*) were selected by polymerase chain reaction (PCR), reverse transcription (RT)-PCR, Southern blotting, enzyme-linked immunosorbent assay (ELISA), and insect bioassay...
2019: Methods in Molecular Biology
Wei Ma, Tianzhen Zhang
Transgenic crops expressing Bacillus thuringiensis (Bt) toxins have become a cornerstone in integrated pest management. To counter rapidly increasing pest resistance to transgenic crops producing single Bt toxins, transgenic plant "pyramids" producing two or more Bt toxins targeting the same pest have been widely adopted. However, cross-resistance and antagonism between Bt toxins limit the sustainability of this approach. Here we describe a new type of pyramid combining protection from a Bt toxin and RNA interference (RNAi)...
2019: Methods in Molecular Biology
Haifeng Chen
Viral vectors carrying suicide genes such as diphtheria toxin, Pseudomonas exotoxin, or barnase are very useful tools in cancer gene therapy and cell ablation research. However, such viral vectors are extremely difficult to produce due to the fact that trace amounts of the toxin will kill any cells used for viral vector production. To overcome this obstacle, we inserted mammalian introns that are not recognized by insect cells to break up the open reading frames (ORFs) of the toxic genes and successfully produced at normal levels of baculoviral and adeno-associated viral (AAV) vectors carrying these toxic genes...
2019: Methods in Molecular Biology
Jian Chen, Tahir Rashid, Guolei Feng, Yan Feng, Aijun Zhang, Michael J Grodowitz
Although insecticidal properties of certain benzoates have been investigated for pest insects and mites, toxicity of benzoates to the red imported fire ants, Solenopsis invicta Buren, has never been reported. In this study, 15 commercially available benzoates were assessed for their contact and fumigation toxicity to S. invicta workers and their chemical structure-activity relationships. Among tested benzoates, benzylbenzoate, n-pentybenzoate, and n-hexylbenzoate were three most potent contact toxins against S...
December 10, 2018: Journal of Economic Entomology
Sridevi Devadas, Subha Bhassu, Tze Chiew Christie Soo, Fatimah M Yusoff, Mohamed Shariff
We sequenced the genome of Vibrio parahaemolyticus strain ST17.P5-S1, isolated from Penaeus vannamei cultured in the east coast of Peninsular Malaysia. The strain contains several antibiotic resistance genes and a plasmid encoding the Photorhabdus insect-related (Pir) toxin-like genes, pirAvp and pirBvp , associated with acute hepatopancreatic necrosis disease (AHPND).
September 2018: Microbiology resource announcements
Kara A Tinker, Elizabeth A Ottesen
Praying mantids are predators that consume a wide variety of insects. While the gut microbiome of carnivorous mammals is distinct from that of omnivores and herbivores, the role of the gut microbiome among predatory insects is relatively understudied. Praying mantids are the closest known relatives to termites and cockroaches, which are known for their diverse gut microbiota. However, little is known about the mantid gut microbiota or their importance to host health. In this work, we report the results of a 16S rRNA gene-based study of gut microbiome composition in adults and late-instar larvae of three mantid species...
2018: PloS One
Abby Basya Finkelstein, Gro V Amdam
Eusocial insects divide their labour so that individuals working inside the nest are affected by external conditions through a cascade of social interactions. Honey bees (Apis mellifera) transfer food and information via mouth-to-mouth social feeding, ie trophallaxis, a process known to be modulated by the rate of food flow at feeders and familiarity of food's scent. Little is understood about how aversive foraging conditions such as predation and con-specific competition affect trophallaxis. We hypothesized that aversive conditions have an impact on food transfer inside the colony...
December 10, 2018: Scientific Reports
Bai-Zhong Zhang, Kang-Sheng Ma, Jun-Jie Liu, Liu-Yang Lu, Xi-Ling Chen, Shou-Ping Zhang, Xi-Wu Gao
BACKGROUND: Insecticides act as toxins, inhibitors of digestion, and deterrents that affect the expression changes of a plenty of genes in insect. To assess the key genes associated with detoxification or regulation of imidacloprid in greenbug, Schizaphis graminum (Rondani), the transcriptome and digital gene expression (DGE) profiling were analyzed by Illumina sequencing. RESULTS: A total of 48,763,494 clean reads were obtained by sequencing. The expression profile analysis showed that 2,782 unigenes were differently expressed between imidacloprid treatment and control groups...
December 7, 2018: Pest Management Science
Ping Lin, Tingcai Cheng, Tieshan Feng, Jiao Gong, Chun Liu, Qingyou Xia
Bacillus thuringiensis (Bt) produces Cry toxins that are widely used as insecticides in agriculture and forestry. Receptors are important to elucidate the mode of interaction with Cry toxins and toxicity in lepidopteran insects. Here, we purified the Cry toxin from Bt and identified this toxin by flight mass spectrometry as Cry1Ac, and then recombinantly expressed aminopeptidase N (BmAPN6) and repeat domains of cadherin-like protein (CaLP) of B. mori. Using co-immunoprecipitation (co-IP), Far-Western blotting, and enzyme-linked immunosorbent assays (ELISAs), we identified the interaction between Cry1Ac and BmAPN6...
November 25, 2018: Sheng Wu Gong Cheng Xue Bao, Chinese Journal of Biotechnology
Jordan D Reinders, Brianna D Hitt, Walter W Stroup, B Wade French, Lance J Meinke
Repeated use of field corn (Zea mays L.) hybrids expressing the Cry3Bb1 and mCry3A traits in Nebraska has selected for field-evolved resistance in some western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) populations. Therefore, this study was conducted to characterize spatial variation in local WCR susceptibility to Cry3Bb1 and mCry3A traits in Keith and Buffalo counties, Nebraska, and determine the relationship between past management practices and current WCR susceptibility. Adult WCR populations were collected from sampling grids during 2015 and 2016 and single-plant larval bioassays conducted with F1 progeny documented significant variation in WCR susceptibility to Cry3Bb1 and mCry3A on different spatial scales in both sampling grids...
2018: PloS One
Katharina Springer, Philipp-Albert Sänger, Christian Moritz, Angela Felsl, Thomas Rattei, Thilo M Fuchs
The genus Yersinia comprises 19 species of which three are known as human and animal pathogens. Some species display toxicity toward invertebrates using the so-called toxin complex (TC) and/or determinants that are not yet known. Recent studies showed a remarkable variability of insecticidal activities when representatives of different Yersinia species (spp.) were subcutaneously injected into the greater wax moth, Galleria mellonella . Here, we demonstrate that Y. intermedia and Y. frederiksenii are highly toxic to this insect...
2018: Frontiers in Cellular and Infection Microbiology
Xenia Bogdanovic, Silvia Schneider, Nadezhda Levanova, Christophe Wirth, Christoph Trillhaase, Marcus Steinemann, Carola Hunte, Klaus Aktories, Thomas Jank
The nematode mutualistic bacterium Photorhabdus asymbiotica produces a large virulence-associated multifunctional protein toxin named PaTox. A glycosyltransferase domain and a deamidase domain of this large toxin function as effectors that specifically target host Rho GTPases and heterotrimeric G proteins, respectively. Modification of these intracellular regulators results in toxicity toward insects and mammalian cells. In this study, we identified a cysteine protease-like domain spanning PaTox residues 1844-2114 (PaToxP ), upstream of these two effector domains and characterized by three conserved amino acid residues (Cys-1865, His-1955, and Asp-1975)...
November 26, 2018: Journal of Biological Chemistry
Angelika Hilbeck, Nicolas Defarge, Thomas Bøhn, Michelle Krautter, Constanze Conradin, Caroline Amiel, Jean-Michel Panoff, Miluse Trtikova
The insecticidal crystal proteins from Bacillus thuringiensis (Bt) are widely-used biopesticides that are used both as Bt spore-crystal preparations in sprayable formulations and as activated toxins in genetically modified (GM) plants. Models for their modes of action have been proposed but many issues remain unresolved. Among those is the role of commensal gut bacteria in target insect death: previous studies showed that antibiotics attenuate the toxicity of Bt sprays. We tested whether antibiotics interfere with the effects of GM plant-produced Bt toxins in larvae of two Lepidopteran species, the European corn borer Ostrinia nubilalis and the cotton leafworm Spodoptera littoralis ...
November 23, 2018: Toxins
Anupama Tuladhar, Robert J Hondal, Ricardo Colon, Elyssa L Hernandez, Kathleen S Rein
The activities of two effectors, brevetoxin (PbTx) and manumycin-A (Man-A), of thioredoxin reductase (TrxR) have been evaluated against a series of fourteen TrxR orthologs originating from mammals, insects and protists and several mutants. Man-A, a molecule with numerous electrophilic sites, forms a covalent adduct with most selenocystine (Sec)-containing TrxR enzymes. The evidence also demonstrates that Man-A can form covalent adducts with some non-Sec-containing enzymes. The activities of TrxR enzymes towards various substrates are moderated by Man-A either positively or negatively depending on the enzyme...
November 23, 2018: Comparative Biochemistry and Physiology. Toxicology & Pharmacology: CBP
Diogo Vieira Tibery, Leandro Ambrósio Campos, Caroline Barbosa Farias Mourão, Steve Peigneur, Andréa Cruz E Carvalho, Jan Tytgat, Elisabeth Ferroni Schwartz
To1, previously named Tc49b, is a peptide neurotoxin isolated from venom of the scorpion Tityus obscurus that is responsible for lethal human poisoning cases in the Brazilian Amazonian region. Previously, To1 was shown to be lethal to mice and to change Na+ permeation in cerebellum granular neurons from rat brain. In addition, To1 did not affect Shaker B K+ channels. Based on sequence similarities, To1 was described as a β-toxin. In the present work, To1 was purified from T. obscurus venom and submitted to an electrophysiological characterization in human and invertebrate NaV channels...
January 2019: Biochimica et biophysica acta. Biomembranes
Huidong Wang, Yu Shi, Lu Wang, Shuai Liu, Shuwen Wu, Yihua Yang, René Feyereisen, Yidong Wu
The cotton bollworm Helicoverpa armigera, is one of the world's major pest of agriculture, feeding on over 300 hosts in 68 plant families. Resistance cases to most insecticide classes have been reported for this insect. Management of this pest in agroecosystems relies on a better understanding of how it copes with phytochemical or synthetic toxins. We have used genome editing to knock out a cluster of nine P450 genes and show that this significantly reduces the survival rate of the insect when exposed to two classes of host plant chemicals and two classes of insecticides...
November 16, 2018: Nature Communications
Dawn L Arnold, Gail M Preston
The lifecycle and pathogenicity mechanisms of Pseudomonas syringae. Transmission: P. syringae can be disseminated by rainsplash, aerosols and airborne plant particles (1), insect vectors (2) or as a seed-borne pathogen (3). If carried into the atmosphere (4), ice-nucleating P. syringae strains can contribute to ice nucleation in clouds and be disseminated in snow or rainfall (5). P. syringae can also be disseminated through terrestrial water systems (6, 8) and through plant debris in soil (7, 8). Symptoms: P...
November 14, 2018: Microbiology
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