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    • Keywords


      ageing; Drosophila melanogaster ; isofemale lines; hormesis; Hsp70; mild heat stress; molecular chaperones

    • Abstract


      In a number of animal species it has been shown that exposure to low levels of stress at a young age has a positive effect on stress resistance later in life, and on longevity. The positive effects have been attributed to the activation of defence/cleaning systems (heat shock proteins (Hsps), antioxidases, DNA repair) or to effects of a changed metabolic rate, or both. We investigated the effect of mild stress exposures early in life on Hsp70 synthesis after a harder stress exposure later in life in five isofemale lines ofDrosophila melanogaster. Female flies were either exposed to repeated bouts of mild heat stress (3 h at 34‡C) at a young age (days 2, 4 and 6 post-eclosion) or held under standard laboratory conditions. At 16 and 32 days of adult age, respectively, flies were exposed to a high temperature treatment known to induce Hsp70 in the investigated species (1 h at 37‡C). Thereafter, the inducible Hsp70 levels were measured. Our data show a tendency towards increased Hsp70 synthesis with increased age for both ’mild stress’ and ’no stress’ flies. Moreover, the results show that flies exposed to mild stress at a young age synthesized more Hsp70 upon induction, compared to control flies, and that this difference was accentuated at 32 days compared to 16 days of age. Thus, bouts of mild heat stress at a young age impact on the physiological stress response system later in life. This may be caused by an increased ability to react to future stresses. Alternatively, the mild stress exposure at a young age may actually have caused cellular damages increasing the need for Hsp70 levels after stress exposure later in life. The importance of an Hsp70 upregulation (throughout life) in explaining the phenomenon of hormesis is discussed, together with alternative hypotheses, and suggestions for further studies.

    • Author Affiliations


      Torsten Nygaard Kristensen1 2 Jesper Givskov SØrensen1 Volker Loeschcke1

      1. Aarhus Centre for Environmental Stress Research (ACES), Department of Ecology and Genetics, University of Aarhus, Building 540, Ny Munkegade, Aarhus C - DK-8000, Denmark
      2. Department of Animal Breeding and Genetics, Danish Institute of Agricultural Sciences, P.O. Box 50, Tjele - DK-8830, Denmark
    • Dates

  • Journal of Genetics | News

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