Search results for "Colorado"
showing 10 items of 45 documents
Role of toxin activation on binding and pore formation activity of the Bacillus thuringiensis Cry3 toxins in membranes of Leptinotarsa decemlineata (…
2004
AbstractBinding and pore formation constitute key steps in the mode of action of Bacillus thuringiensis δ-endotoxins.In this work, we present a comparative analysis of toxin-binding capacities of proteolytically processed Cry3A, Cry3B and Cry3C toxins to brush border membranes (BBMV) of the Colorado potato beetle Leptinotarsa decemlineata (CPB), a major potato coleopteran-insect pest. Competition experiments showed that the three Cry3 proteolytically activated toxins share a common binding site. Also heterologous competition experiments showed that Cry3Aa and Cry3Ca toxins have an extra binding site that is not shared with Cry3Ba toxin. The pore formation activity of the three different Cry…
A membrane associated metalloprotease cleaves Cry3Aa Bacillus thuringiensis toxin reducing pore formation in Colorado potato beetle brush border memb…
2007
AbstractInsect proteases are implicated in Bacillus thuringiensis insecticidal proteins mode of action determining toxin specificity and sensitivity. Few data are available on the involvement of proteases in the later steps of toxicity such as protease interaction with toxin–receptor complexes and the pore formation process. In this study, a Colorado potato beetle (CPB) midgut membrane metalloprotease was found to be involved in the proteolytic processing of Cry3Aa. Interaction of Cry3Aa with BBMV membrane proteases resulted in a distinct pattern of proteolysis. Cleavage was demonstrated to occur in protease accessible regions of domain III and was specifically inhibited by the metalloprote…
Proteolytic Processing ofBacillus thuringiensisCryIIIA Toxin and Specific Binding to Brush-Border Membrane Vesicles ofLeptinotarsa decemlineata(Color…
1996
Abstract The mode of action of Bacillus thuringiensis insecticidal proteins in lepidopteran insects is known to involve five steps: ingestion, solubilization, protease activation, binding to midgut membrane receptors, and disruption of the intestinal membrane. Two of these steps, protease activation and binding to midgut membrane receptors, have been analyzed in the major potato pest, the coleoptera Leptinotarsa decemlineata (Colorado potato beetle). Unlike recently proposed, after treatment of the coleopteran-specific B. thuringiensis toxin CryIIIA with gut content from the Colorado potato beetle, a 42-kDa processing polypeptide has been identified. The study of binding to midgut membrane …
Functional significance of membrane associated proteolysis in the toxicity of Bacillus thuringiensis Cry3Aa toxin against Colorado potato beetle.
2012
Abstract Bacillus thuringiensis Cry toxins are widely used as biocontrol agents in bioinsecticides and transgenic plants. In the three domain-Cry toxins, domain II has been identified as an important determinant of their highly specific activity against insects. In this work, we assessed the role in membrane associated proteolysis and toxicity in Colorado potato beetle (CPB) of a previously reported ADAM recognition motif present in Cry3Aa toxin domain II. We used site-directed mutagenesis to modify the Bacillus thuringiensis cry3A gene in amino acid residues 344, 346, 347, 351 and 353 of the ADAM recognition motif in Cry3Aa toxin. Cry3Aa toxin mutants displayed decreased toxicity when comp…
Unveiling gene expression regulation of the Bacillus thuringiensis Cry3Aa toxin receptor ADAM10 by the potato dietary miR171c in Colorado potato beet…
2021
Background The Colorado potato beetle (CPB) is a worldwide devastating pest of potato plants and other Solanaceae characterized by its remarkable ability to evolve resistance to insecticides. Bacillus thuringiensis (Bt) Cry3Aa toxin represents an environmentally-safe alternative for CPB control but larvae susceptibility to this toxin has been reported to vary depending on the host plant on which larvae feed. To gain more insight into how nutrition mediates Bt tolerance through effects on gene expression here we explored the post-transcriptional regulation by miRNAs of the CPB-ADAM10 gene encoding the Cry3Aa toxin functional receptor ADAM10. Results The lower CPB-ADAM10 gene expression in CP…
Pre-invasion history and demography shape the genetic variation in the insecticide resistance-related acetylcholinesterase 2 gene in the invasive Col…
2012
Abstract Background Invasive pest species offers a unique opportunity to study the effects of genetic architecture, demography and selection on patterns of genetic variability. Invasive Colorado potato beetle (Leptinotarsa decemlineata) populations have experienced a rapid range expansion and intense selection by insecticides. By comparing native and invasive beetle populations, we studied the origins of organophosphate (OP) resistance-associated mutations in the acetylcholinesterase 2 (AChE2) gene, and the role of selection and demography on its genetic variability. Results Analysis of three Mexican, two US and five European populations yielded a total of 49 haplotypes. Contrary to the exp…
Energy use, diapause behaviour and northern range expansion potential in the invasive Colorado potato beetle
2011
Summary 1. As organisms expand their range towards northern latitudes they will encounter selective factors like harsh winter conditions. The ability to cope with and adapt to harsh winters may depend on the variability and evolutionary potential of relevant traits. 2. One adaptation in insects is winter diapause. It is characterized by changes in physiology, behaviour or in both. Physiological changes include lowered metabolic rate that enhances survival by saving limited energy reserves during overwintering. Active behavioural changes like burrowing into the soil allow individuals to escape harsh conditions. 3. We examined variation in overwintering body mass, resting metabolic rate (CO2 …
Northward range expansion requires synchronization of both overwintering behaviour and physiology with photoperiod in the invasive Colorado potato be…
2014
Abstract. Photoperiodic phenological adaptations are prevalent in many organisms living in seasonal environments. As both photoperiod and growth season length change with latitude, species undergoing latitudinal range expansion often need to synchronize their life cycle with a changing photoperiod and growth season length. Since adaptive synchronization often involves a large number of time-consuming genetic changes, behavioural plasticity might be a faster way to adjust to novel conditions. We compared behavioural and physiological traits in overwintering (diapause) preparation in three latitudinally different European Colorado potato beetle (Leptinotarsa decemlineata) populations reared u…
The voyage of an invasive species across continents: genetic diversity of North American and European Colorado potato beetle populations
2005
The paradox of successful invading species is that they are likely to be genetically depauperate compared to their source population. This study on Colorado potato beetles is one of the few studies of the genetic consequences of continent-scale invasion in an insect pest. Understanding gene flow, population structure and the potential for rapid evolution in native and invasive populations offers insights both into the dynamics of small populations that become successful invaders and for their management as pests. We used this approach to investigate the invasion of the Colorado potato beetle (Leptinotarsa decemlineata) from North America to Europe. The beetles invaded Europe at the beginnin…
Responses in metabolic rate to changes in temperature in diapausing Colorado potato beetleLeptinotarsa decemlineatafrom three European populations
2015
Many insects survive adverse periods in seasonal environments by entering diapause, a deep resting stage, during which energy consumption is typically low and gas exchange is in the form of a discontinuous gas exchange cycle (DGC). Because insects in high-latitude environments are severely time constrained during summer, an effective diapause termination with careful regulation of metabolic rate is important. The present study examines whether diapausing Colorado potato beetles Leptinotarsa decemlineataSay originating from three latitudinally different regions in Europe differ in their quantitative or qualitative gas exchange patterns in response to an increasing temperature. Overall produc…