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Abstract: It has been suggested that reactive oxygen species (ROS) participate in the injury and death of sensitive plants treated with auxin herbicides. However, their precise role in the phytotoxicity [...]

Recent research has focused on the importance of behavior in mediating the effects of landscape change on amphibian populations and communities. Factors such as chemical contaminants may affect habitat selection and movement of amphibians in human-altered habitats and contribute to landscape-level patterns of distribution and abundance. The objective of this study was to determine if the Strawberry Poison Frog (Oophaga pumilio (Schmidt, 1857)) can use olfactory cues to detect and avoid the glyphosate-based herbicide Roundup(tm). Fifty frogs were captured in the field in Costa Rica and tested in experimental arenas where they were given a choice between a control and an herbicide treatment. Analysis of time spent in treatment areas revealed a significant interaction between sex and treatment. Analyses of choice at the start and end of the trials indicated that sex and cardinal direction were important factors influencing orientation behavior. These results suggest that males and females differed in their behavioral responses, and that male O. pumilio may use olfactory cues to detect and avoid areas treated with glyphosate-based herbicide. However, the sampled population was male-biased, which resulted in a lower sample size and lower power to detect an effect for females. Further work is needed to better understand amphibian behavioral responses to herbicides, as well as the role of sex and individual variation in modifying these responses. Key words: amphibian, avoidance, glyphosate, terrestrial, agricultural, landscape, sex, dispersal, choice, experiment, land use, Oophaga pumilio, Strawberry Poison Frog. Des travaux recents se sont interesses a l'importance du comportement sur la mediation des effets des modifications du paysage sur les populations et les communautes d'amphibiens. Des facteurs comme les polluants chimiques peuvent avoir une incidence sur la selection de l'habitat et les deplacements des amphibiens dans les habitats modifies par les humains et ainsi influer sur leur repartition et leur abondance a l'echelle du paysage. L'objectif de l'etude consistait a verifier si le dendrobate fraise (Oophaga pumilio (Schmidt, 1857)) peut utiliser des signaux olfactifs pour detecter et eviter le RoundupMC, un herbicide a base de glyphosate. Cinquante grenouilles ont ete capturees sur le terrain au Costa Rica et fait l'objet d'essais dans des arenas experimentales ou elles avaient le choix entre un traitement temoin et un traitement a l'herbicide. L'analyse du temps passe dans les zones de traitement revele une interaction significative entre le sexe et le traitement. Des analyses du choix au debut et a la fin des essais indiquent que le sexe et la direction cardinale etaient des facteurs qui avaient une importante influence sur le comportement d'orientation. Les resultats indiqueraient des reactions comportementales differentes pour les males et les femelles, et que les O. pumilio males pourraient utiliser des signaux olfactifs pour detecter et eviter les zones traitees a l'herbicide a base de glyphosate. La population echantillonnee comptait toutefois plus de males que de femelles, ce qui se traduit par un plus petit echantillon de femelles et donc une puissance de detection plus faible des effets chez ces dernieres. D'autres travaux sont necessaires pour etablir une meilleure comprehension des reactions comportementales des amphibiens aux herbicides, ainsi que du role du sexe et des variations entre individus dans la modification de ces reactions. [Traduit par la Redaction] Mots-cles : amphibien, evitement, glyphosate, terrestre, agricole, paysage, sexe, dispersion, choix, experience, utilisation du territoire, Oophaga pumilio, dendrobate fraise., Introduction Worldwide amphibian populations are experiencing dramatic declines (Stuart et al. 2004; Whitfield et al. 2007). Of the factors contributing to declines, habitat loss and degradation are among the most [...]

Introduction Chickpea (Cicer arietinum L.), originating from present day southeastern Turkey and Syria (Van der Maesen 1987), is a relatively new pulse crop introduced to the Canadian Prairies as a [...], Chickpea (Cicer arietinum L.) production in the Canadian prairies is challenging due to a lack of effective weed management mainly because of poor competition ability of the crop and limited registered herbicide options. Chickpea genotype with resistance to imidazolinone (IMI) herbicides has been identified. A point mutation in the acetohydroxyacid synthasel (AHAS1) gene at C581 to T581, resulting in an amino acid substitution from Ala194 to Val194 (position 205, standardized to arabidopsis), confers the resistance to imazamox in chickpea. However, the molecular mechanism leading to the resistance is not fully understood. In many plant species, contrasting transcription levels of AHAS gene has been implicated in the resistant and susceptible genotypes in response to IMI. The objectives of this research were to compare the AHAS gene expression and AHAS enzyme activity in resistant and susceptible chickpea cultivars in response to imazamox herbicide treatment. Results from RT-qPCR indicated that there is no significant change in the transcript levels of AHAS1 between the susceptible and the resistant genotypes in response to imazamox treatment. Protein hydrophobic cluster analysis, protein-ligand docking analysis, and AHAS enzyme activity assay all indicated that the resistance to imazamox in chickpea is due to the alteration of interaction of the AHAS1 enzyme with the imazamox herbicide. Key words: chickpea, resistance, imazamox, acetohydroxyacid synthase, enzyme activity, colorimetric assay. La production du pois chiche (Cicer arietinum L.) dans les Praires canadiennes est difficile surtout en raison du mauvais controle des mauvaises herbes, lequel decoule de la faible capacite concurrentielle de la culture et du nombre limite d'herbicides enregistres. Un genotype du pois chiche avec une resistance aux imidazolinones (IMI) a ete identifie. Une mutation ponctuelle (C581 a T581) au sein du gene de l'acetohydroxyacide-synthetase 1 (AHAS1) entrame une substitution d'un acide amine (Ala194 a Val194, position 205 chez arabidopsis), laquelle confere la resistance a l'imazamox chez le pois chiche. Cependant, le mecanisme moleculaire menant a cette resistance n'est pas pleinement compris. Chez plusieurs especes vegetales, des differences dans l'abondance du transcrit du gene AHAS ont ete trouvees responsables des genotypes resistants et sensibles en reponse aux IMI. Les objectifs de ce travail etaient de comparer l'expression genique et l'activite enzymatique de l'AHAS chez des cultivars resistant ou sensible en reponse a l'application de l'herbicide imazamox. Les resultats d'une analyse RT-qPCR n'ont indique aucune difference significative en ce qui a trait a l'abondance du transcrit de ce gene chez les genotypes sensible et resistant suite a l'arrosage avec l'imazamox. Une analyse des groupements hydrophobes de la proteine, de l'arrimage proteine-ligand ainsi qu'une mesure de l'activite enzymatique ont toutes indique que la resistance a l'imazamox chez le pois chiche serait due a une alteration de l'interaction entre l'enzyme AHAS1 et l'herbicide imazamox. [Traduit par la Redaction] Mots-cles : pois chiche, resistance, imazamox, acetohydroxyacide-synthetase, activite enzymatique, mesure colorimetrique.

ABSTRACT. Agricultural chemicals, such as pesticides and herbicides, play an important role in agricultural operations to control unwanted pests and maximize crop yield. However, these chemicals may also threaten aquatic [...]

Acetyl-CoA carboxylases (ACCs) are crucial metabolic enzymes and are attractive targets for drug discovery. Haloxyfop and tepraloxydim belong to two distinct classes of commercial herbicides and kill sensitive plants by inhibiting the carboxyltransferase (CT) activity of ACC. Our earlier structural studies showed that haloxyfop is bound near the active site of the CT domain, at the interface of its dimer, and a large conformational change in the dimer interface is required for haloxyfop binding. We report here the crystal structure at 2.3 [Angstrom] resolution of the CT domain of yeast ACC in complex with tepraloxydim. The compound has a different mechanism of inhibiting the CT activity compared to haloxyfop, as well as the mammalian ACC inhibitor CP-640186. Tepraloxydim probes a different region of the dimer interface and requires only small but important conformational changes in the enzyme, in contrast to haloxyfop. The binding mode of tepraloxydim explains the structure-activity relationship of these inhibitors, and provides a molecular basis for their distinct sensitivity to some of the resistance mutations, as compared to haloxyfop. Despite the chemical diversity between haloxyfop and tepraloxydim, the compounds do share two binding interactions to the enzyme, which may be important anchoring points for the development of ACC inhibitors. diabetes | fatty acid metabolism | herbicides | structure-based drug design doi/10.1073/pnas.0908431106

INTRODUCTION: Investigators have hypothesized that consuming pesticide-contaminated well water plays a role in Parkinson's disease (PD), and several previous epidemiologic studies support this hypothesis. OBJECTIVES: We investigated whether consuming water [...]

To probe the connection between longevity and stress resistance, we compared the sensitivity of Ames long-lived dwarf mice and control littermates with paraquat, diquat, and dobutamine. In young adult animals, 95% of male and 39% of female controls died after paraquat administration, but no dwarf animals died. When the experiment was repeated at an older age or a higher dosage of paraquat, dwarf mice still showed greater resistance. Dwarf mice also were more resistant to diquat; 80% of male and 60% of female controls died compared with 40% and 20% of dwarf mice, despite greater sensitivity of dwarf liver to diquat. Dwarf mice were also less sensitive to dobutamine-induced cardiac stress and had lower levels of liver and lung [F.sub.2]-isoprostanes. This is the first direct in vivo evidence that long-lived Ames dwarf mice have enhanced resistance to chemical insult, particularly oxidative stressors. Key Words: Reactive oxygen species--Liver--Ames dwarf mice--Paraquat--Diquat.

A comprehensive review of atrazine including its use, properties, environmental fate, toxicological effects, occurrence in water, a summary of criteria for drinking water and the efficiency of various water treatment options for its removal was Conducted. Atrazine is ubiquitous in surface water, groundwater, and precipitation, due to its widespread use for the control of broadleaf and grassy weeds mainly in com crops. Atrazine is considered a priority substance by (he USEPA, Agriculture Canada, and the European Commission. It causes developmental deformities and impacts behavior in frogs and fish. Atrazine has been implicated as a possible endocrine disrupting compound and has been associated with various cancers in humans such as stomach, prostate, breast, and non-Hodgkin's lymphoma. Guidelines and standards governing maximum acceptable concentrations in fresh and marine waters are scarce and those for drinking water vary significantly between agencies. The effectiveness of tertiary water treatment technologies for the removal of atrazine demonstrates varying efficiencies. Variations in the quality of source water and the presence of natural organic matter present significant challenges for its removal. Key words: atrazine. endocrine disrupter, potable water, tertiary treatment, natural organic matter. On a fait un compte rendu detaille sur l'atrazine y compris ses usages, ses proprietes, son devenir dans l'environnement, sa toxieite, sa presence dans l'eau, un sommaire des criteres pour l'eau potable et l'efficacite de diverses methodes de traitement de l'eau potable. L'atrazine est omnipresenle dans les eaux de surface, dans les eaux souterraine et dans les precipitations a cause de son usage tres repandu pour la lutte conlre les mauvaises herbes dicotyledones el graminees en cultures de mais. L'herbicide atrazine est considere comme un contaminant prioritaire par l'USEPA, Agriculture Canada et la Commission Europeenne. Plusieurs chercheurs ont etabli un lien entre l'exposition a l'atrazine et des malformations on des effets sur le comportement des grenouilles et des poissons. L'atrazine pouvait perturber les systemes endocriniens. De plus, l'herbicide a ete aussi associee aux cancers de l'estomac, de la prostate, du sein et de lymphome non hodgkinien. Les criteres des concentrations maximales aceeptables des eaux douces et sales sont rares et ceux pour l'eau potable varient considerablement entre les agences de l'environnement. L'efficacite des technologies tertiaires de traitement de l'eau potable demontrent des niveaux d'enlevement tres variables. La qualite de l'eau brute et la presence des matieres organiques sont les facteurs qui posent les plus grands defis pour son elimination dans l'eau potable. Mots-des : atrazine, perturbateur endocrinien. eau potable, traitement tertiaire, matieres organiques., Introduction Atrazine is a chloro-s-triazine belonging to the triazine group of synthetic organic herbicides. It is one of the most frequently applied herbicides in the agricultural sector for selective control [...]