24/05 : SEMINAIRES ECOBIO DE KEVIN NOORT et SAPHO-LOU MARTI (ECOBIO)
Dans le cadre des séminaires d'équipe ECOBIO, Kevin Noort et Sapho-Lou Marti de l'équipe Phénome présentent leurs travaux de recherche le vendredi 24 mai à 13h au cours de deux séminaires intitulés "Behavioral, physiological and molecular basis of insecticide resistance in an invasive insect Alphitobius diaperinus (Tenebrionidae) in agro-ecosystem" et "Temporal expression of chaperome-related genes in Drosophila melanogaster exposed to thermal stress"
ATTENTION CHANGEMENT DE SALLE le séminaire se passera dans la salle B. Auvray, bâtiment 15.
Résumé des présentations
Behavioral, physiological and molecular basis of insecticide resistance in an invasive insect Alphitobius diaperinus (Tenebrionidae) in agro-ecosystem
Alphitobius diaperinus (Tenebrionidae) is a cosmopolitan pest insect that reduces livestock profits and animal welfare in the poultry farming industry. Firstly, by feeding on chicken feed, weakened chickens and carrion, and effectively reducing poultry weight gain; secondly, by transmitting viruses and pathogens within flocks, among flocks and towards costumers; and lastly, by destroying wall and isolation material of broiler facilities. The conventional method of controlling A. diaperinus populations is by spraying organophosphate or pyrethroid insecticides on the ground and walls when the facility is empty. At a broiler farm near Rennes, this method has been used consistently for 20+ years using the pyrethroid ß-cyfluthrin, during which the beetle population developed resistance against this insecticide. In order to determine the biochemical and behavioral mechanisms by which the resistance is attained, this resistant population, called Mainfray, was compared with a susceptible population, called Envie. These populations were studied on the enzymatic activity of glutathione-s-transferase (GST), cytochrome P450 (P450), non-specific esterase (nsE) and on acetylcholinesterase insensitivity (AChE). These beetles were pre-exposed to indicated concentrations of ß-cyfluthrin or control for 24 hours, after which they were frozen for later biochemical testing. The enzymatic activity was determined for 12 replicates per group, with 3 individuals per replicate. Behavior was assayed by recording 4 beetles for 10 minutes in arenas that were half-treated or untreated with ß-cyfluthrin. Behavior was later quantified using the BEMOVI tracking tool. Our findings show that Mainfray beetles have increased enzymatic activity of GSTs and P450s enzymes compared to Envie beetles. Furthermore, Mainfray’s enzymatic activity of acetylcholinesterase, both inhibited and uninhibited, is also increased. Results of the behavioral analysis are forthcoming, however, there does not seem to be a difference between Envie and Mainfray behavior.
Temporal expression of chaperome-related genes in Drosophila melanogaster exposed to thermal stress
All organisms have mechanisms to resist environmental insults (biotic or abiotic stress). When exposed to stress, cells activate the expression of a particular class of proteins called heat shock proteins (HPSs). The role of these chaperones is to repair damaged proteins (unfolded) by stress or to coordinate their degradation. This mechanism of protection is extremely conserved through evolution from bacteria to humans. The "CHAPEROME" corresponds to all molecular chaperones and co-chaperones that interact in a complex network to ensure cellular homeostasis and the proper functioning of the proteome. The functions of the main and most common chaperones (eg Hsp70 or Hsp90) are quite well known, but functions and expression patterns of the many other chaperones remain very little studied. In addition, the integrative dynamic network of chaperome in response to stress is poorly characterized. Little is known about the whole chaperome reactions even in model organisms. In this project, we studied the temporal expression of 135 D. melanogaster chaperome-related genes over the course of a heat and cold stress exposure and recovery. Increased or decreased expression in many genes was found in response to stress, with differences according to the stress nature (cold or hot). In both cases, we observed peaks of expression of many genes 2 hours after the stress. The most responsive genes in both stress were quite similar, showing a common response to thermal stress. We also identified several genes specifically responding to either cold or heat, showing dissimilarity of the stress response networks between heat and cold stress.
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