tailieunhanh - Báo cáo khoa học: Cold exposure and associated metabolic changes in adult tropical beetles exposed to fluctuating thermal regimes

Environmental stress deleteriously affects every aspect of an ectotherm’s biological function. Frequent exposure of terrestrial insects to temperature variation has thus led to the evolution of protective biochemical and phy-siological mechanisms. However, the physiological mechanisms underlying the positive impact of fluctuating thermal regimes (FTRs) on the fitness and survival of cold-exposed insects have not been studied. | ỊFEBS Journal Cold exposure and associated metabolic changes in adult tropical beetles exposed to fluctuating thermal regimes L. Lalouette1 V. Kostal2 H. Colinet3 D. Gagneul4 5 and D. Renault1 1 UMR CNRS 6553 Université de Rennes 1 Rennes France 2 Institute of Entomology Biology Centre AS CR Ceske Budejovice Czech Republic 3 Unite d Ecologie et de Biogeographie Centre de Recherche sur la Biodiversite Universite catholique de Louvain Louvain-la-Neuve Belgium 4 UMR CNRS 6026 Universite de Rennes 1 Rennes France 5 Department of Plant Biology Michigan State University East Lansing MI USA Keywords amino acid fluctuating thermal regime insect polyol sugar Correspondence D. Renault UMR CNRS 6553 University of Rennes 1 Bat. 14A 263 Avenue du Gal Leclerc CS 74205 35042 Rennes Cedex France Fax 33 2 23235046 Tel 33 2 23236627 E-mail Website http Received 13 November 2006 revised 26 January 2007 accepted 1 February 2007 doi Environmental stress deleteriously affects every aspect of an ectotherm s biological function. Frequent exposure of terrestrial insects to temperature variation has thus led to the evolution of protective biochemical and physiological mechanisms. However the physiological mechanisms underlying the positive impact of fluctuating thermal regimes FTRs on the fitness and survival of cold-exposed insects have not been studied. We have thus investigated the metabolic changes in adults of the beetle Alphitobius diaperinus in order to determine whether FTRs trigger the initiation of a metabolic response involving synthesis of protective compounds such as free amino acids FAAs and polyols. The metabolic profile was analyzed during constant fluctuating thermal regimes the beetles had daily pulses at higher temperatures that enabled them to recover and compared with constant cold exposure and untreated controls. The increase of several essential amino acids Lys Iso Leu Phe and Trp in