Search results for "INSECTICIDES"
showing 10 items of 166 documents
Increased recovery of brain acetylcholinesterase activity in dichlorvos-intoxicated European eels Anguilla anguilla by bath treatment with N-acetylcy…
2003
Organophosphate (OP) pesticides are widely used as antiparasitic chemicals in finfish aquaculture. However, current antidotes cannot be applied to treat intoxicated fish. We showed in previous studies the importance of glutathione (GSH) metabolism in pesticide resistance of the European eel Anguilla anguilla L. The present work studied the effects of the antioxidant and glutathione pro-drug N-acetyl-l-cysteine (NAC) on the recovery of European eels exposed for 96 h to a sublethal concentration (0.17 mg l^-1; 20% of its 96 h LC50) of the OP pesticide dichlorvos (2,2-dichlorovinyl dimethyl phosphate; DDVP). This insecticide and acaricide decreased muscular GSH content and increased oxidised g…
Phenothiazines interfere with dopaminergic neurodegeneration in Caenorhabditis elegans models of Parkinson's disease
2010
Oxidative stress is involved in the pathogenesis of various neurodegenerative disorders, conventional antioxidant strategies have yet been of limited success. We have employed transgenic Caenorhabditis elegans expressing DsRed2 in dopaminergic neurons and CFP pan-neuronally, to characterize in larval and adult animals the effects of rotenone and 1-methyl-4-phenyl-pyridinium (MPP(+)) on the dopaminergic system. Investigating the antioxidant phenothiazine and different derived antipsychotic drugs, it was found that free phenothiazine exerted strong neuroprotection at the cellular level and resulted in a better performance in behavioral assays, whereas apomorphine and other dopamine agonists o…
Domain shuffling between Vip3Aa and Vip3Ca: chimera stability and insecticidal activity against European, American, African, and Asian pests
2020
The bacterium Bacillus thuringiensis produces insecticidal Vip3 proteins during the vegetative growth phase with activity against several lepidopteran pests. To date, three different Vip3 protein families have been identified based on sequence identity: Vip3A, Vip3B, and Vip3C. In this study, we report the construction of chimeras by exchanging domains between Vip3Aa and Vip3Ca, two proteins with marked specificity differences against lepidopteran pests. We found that some domain combinations made proteins insoluble or prone to degradation by trypsin as most abundant insect gut protease. The soluble and trypsin-stable chimeras, along with the parental proteins Vip3Aa and Vip3Ca, were tested…
Screening for Bacillus thuringiensis Crystal Proteins Active against the Cabbage Looper, Trichoplusia ni
2000
Abstract Toxicity tests were performed to find among Cry1 and Cry2 Bacillus thuringiensis crystal proteins those with high activity against the cabbage looper. Tests were performed with neonate larvae on surface-contaminated artificial diet. The crystal proteins found to be toxic were, from higher to lower toxicity: Cry1Ac, Cry1Ab, Cry1C, Cry2Aa, Cry1J, and Cry1F (LC50 of 1.1–4.1, 3.4–4.4, 12, 34, 87, and 250 ng/cm2, respectively). Cry1B, Cry1D, and Cry1E can be considered nontoxic (LC50 higher than 2500 ng/cm2). Cry1Aa was moderately toxic to nontoxic, depending on the source (LC50 of 420 ng/cm2 from PGS and 8100 ng/cm2 from Ecogen). In vitro binding assays with trypsin-activated 125I-labe…
Synergism and Antagonism between Bacillus thuringiensis Vip3A and Cry1 Proteins in Heliothis virescens, Diatraea saccharalis and Spodoptera frugiperda
2014
Made available in DSpace on 2015-03-18T15:56:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-10-02Bitstream added on 2015-03-18T16:28:28Z : No. of bitstreams: 1 WOS000342591500006.pdf: 270331 bytes, checksum: c280e3f5bc5e3bb0b92bf74d046135f0 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Spanish Ministry of Economy and Competivity FEDER Second generation Bt crops (insect resistant crops carrying Bacillus thuringiensis genes) combine more than one gene that codes for insecticidal proteins in the same plant to provide better control of agricultural pests. Some of the new combinations involve co-expression of cry and vip genes. Because Cry and Vip proteins …
A Genomic and Proteomic Approach to Identify and Quantify the Expressed
2018
The combined analysis of genomic and proteomic data allowed us to determine which cry and vip genes are present in a Bacillus thuringiensis (Bt) isolate and which ones are being expressed. Nine Bt isolates were selected from Spanish collections of Bt based on their vip1 and vip2 gene content. As a first step, nine isolates were analyzed by PCR to select those Bt isolates that contained genes with the lowest similarity to already described vip1 and vip2 genes (isolates E-SE10.2 and O-V84.2). Two selected isolates were subjected to a combined genomic and proteomic analysis. The results showed that the Bt isolate E-SE10.2 codifies for two new vegetative proteins, Vip2Ac-like_1 and Sip1Aa-like_…
Different mechanisms of resistance to Bacillus thuringiensis toxins in the indianmeal moth.
2001
ABSTRACT Susceptibility to protoxin and toxin forms of Cry1Ab and the binding of 125 I-labeled Cry1Ab and Cry1Ac has been examined in three Plodia interpunctella colonies, one susceptible (688 s ) and two resistant (198 r and Dpl r ) to Bacillus thuringiensis . Toxicological studies showed that the 198 r colony was 11-fold more resistant to Cry1Ab protoxin than to Cry1Ab activated toxin, whereas the Dpl r colony was 4-fold more resistant to protoxin versus toxin. Binding results with 125 I-labeled toxins indicated the occurrence of two different binding sites for Cry1Ab in the susceptible insects, one of them shared with Cry1Ac. Cry1Ab binding was found to be altered in insects from both re…
Susceptibility of Spodoptera exigua to 9 toxins from Bacillus thuringiensis
2007
Nine of the most common lepidopteran active Cry proteins from Bacillus thuringiensis have been tested for activity against Spodoptera exigua. Because of possible intraspecific variability, three laboratory strains (FRA, HOL, and MUR) have been used. Mortality assays were performed with the three strains. LC(50) values for the active toxins were determined to the FRA and the HOL strains, whereas susceptibility of the MUR strain was assessed using only two concentrations. The results showed that Cry1Ca, Cry1Da, and Cry1Fa were the most effective toxins with all strains. Cry1Ab was found effective for the HOL strain, but very little effective against FRA (6.5-fold) and MUR strains. Cry1Aa and …
Mechanism of Resistance to Bacillus thuringiensis Toxin Cry1Ac in a Greenhouse Population of the Cabbage Looper, Trichoplusia ni
2007
ABSTRACT The cabbage looper, Trichoplusia ni , is one of only two insect species that have evolved resistance to Bacillus thuringiensis in agricultural situations. The trait of resistance to B. thuringiensis toxin Cry1Ac from a greenhouse-evolved resistant population of T. ni was introgressed into a highly inbred susceptible laboratory strain. The resulting introgression strain, GLEN-Cry1Ac-BCS, and its nearly isogenic susceptible strain were subjected to comparative genetic and biochemical studies to determine the mechanism of resistance. Results showed that midgut proteases, hemolymph melanization activity, and midgut esterase were not altered in the GLEN-Cry1Ac-BCS strain. The pattern of…
Binding of individual Bacillus thuringiensis Cry proteins to the olive moth Prays oleae (Lepidoptera: Yponomeutidae)
2009
The microlepidopteran Prays oleae is one of the main insect pests causing significant crop losses in the Mediterranean olive groves. Bacillus thuringiensis based insecticides are being successfully used to minimize the impact of the second and third generations of this pest. However, because of its very small size and difficulty of rearing, very few studies have been carried out to determine the potency and mode of action of B. thuringiensis Cry proteins in this insect. In this study, Cry1Ac, Cry1Ca, and Cry1Fa proteins were shown to be toxic to third instar larvae of P. oleae. Furthermore, binding assays with (125)I-Cry1Ac and brush border membrane vesicles from midguts of last-instar larv…