Hormesis and debilitation effects in stress experiments using the nematode worm Caenorhabditis elegans:: the model of balance between cell damage and HSP levels

In this article, we discuss mechanisms responsible for the effects of heat treatment on increasing subsequent survival in the nematode worm Caenorhabditis elegans. We assume that the balance between damage associated with exposure to thermal stress and the level of heat shock proteins produced plays a key role in forming the age-pattern of mortality and survival in stress experiments. We propose a stochastic model of stress, which describes the accumulation of damage in the cells of the worm as the worm ages. The model replicates the age trajectories of experimental survival curves in three experiments in which worms were heat-treated for 0, 1, 2, 4, 6, or 8 h. We also discuss analytical results and directions of further research. The proposed method of stochastic modelling of survival data provides a new approach that can be used to model, analyse and extrapolate experimental results. (C) 2001 Elsevier Science Inc. All rights reserved.