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Lectins are carbohydrate binding proteins which are widely distributed in nature: they have been isolated from microorganisms, fungi, plants and animals. Many of these proteins were tested for their potential biocide effect on lot of pests. Indeed, lectins can cause dramatic changes in the cellular morphology and metabolism, particularly on the digestive system of insect having ingested them, by lectin binding to membrane glycosyl groups of the digestive tract cells. A fungal lectin, namely Xerocomus Chrysenteron lectin (XCL) was previously purified and was shown to be toxic to several pests including aphids. At the cell level, an increase in the endocytosis, the induction of morphological changes such as the actin cytoskeleton shape was determined. In this work, the recombinant XCL was produced and was tested for its potential aphicid...
Extensive utilization of pesticides against insects provides us with a good model for studying the adaptation of a eukaryotic genome to a strong selective pressure. One mechanism of resistance is the alteration of acetylcholinesterase (EC 3.1.1.7), the molecular target for organophosphates and carbamates. Here, we report the sequence analysis of the Ace gene in several resistant field strains of Drosophila melanogaster. This analysis resulted in the identification of five point mutations associated with reduced sensitivities to insecticides. In some cases, several of these mutations were found to be combined in the same protein, leading to different resistance patterns. Our results suggest that recombination between resistant alleles preexisting in natural populations is a mechanism by which insects rapidly adapt to new selective press...
Widespread contamination of land and groundwater has resulted from the use, manufacture, and storage of the military explosive hexa-hydro-1,3,5-trinitro-1,3,5-triazine (RDX). This contamination has led to a requirement for a sustainable, low-cost method to remediate this problem. Here, we present the characterization of an unusual microbial P450 system able to degrade RDX, consisting of flavodoxin reductase XplB and fused flavodoxin-cytochrome P450 XplA. The affinity of XplA for the xenobiotic compound RDX is high (K d = 58 μM) and comparable with the K m of other P450s toward their natural substrates (ranging from 1 to 500 μM). The maximum turnover (k cat) is 4.44 per s, only 10-fold less than the fastest self-sufficient P450 reported, BM3. Interestingly, the presence of oxygen determines the final products of RDX degradation, demonst...
The reversible addition-fragmentation chain transfer (RAFT) polymerization technique has been employed to synthesize various linear tetrathiafulvalene end-functionalized polymers. n-Butyl acrylate, N-isopropylacrylamide, and styrene monomers were polymerized in the presence of azobis(isobutyronitrile) and a new tetrathiafulvalene (TTF) trithiocarbonate derivative as reversible chain transfer agent. All RAFT polymerizations exhibited pseudo-first-order kinetics, a linear increase of the number-average molar mass (M-n SEC) with conversion and narrow molar mass distributions (polydispersity < 1.3). The resulting homopolymers exhibited alpha-TTF and omega-trithiocarbonyl end groups. Cyclic voltammetry Was Used to investigate the electrochemical properties of the TTF polymers. Finally, we have shown that the TTF moiety at the alpha-chain...
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