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(58-04) Exogeneous cycles, endogeneous cycles and microevolution: sources of stress marker variability and baselines for ecotoxicological effect assessment. Köhler, Heinz-R.*,1, Abdel-Latif, Hassan2,3, Adam, Stefan1, Gayle, Peter4, Knigge, Thomas1, Schill, Ralph1, Seniczak, Anna5, Triebskorn, Rita1,6, 1 Animal Physiological Ecology, University of Tübingen, Konrad-Adenauer-Str. 20, Tübingen, Germany2 Dept. of Zoology, Faculty of Science, University of Alexandria, Alexandria, Egypt3 Dept. of Biology, University of Umm Al Qura, P.O. Box 715, Makkah, Saudi-Arabia4 Center for Marine Sciences, Discovery Bay Marine Lab, University of the West Indies, St. Ann, Jamaica5 Dept. of Ecology, University of Technology and Agriculture, ul. Ks. Kordeckiego 20, Bydgoszcz, Poland6 Steinbeis-Transfer Center for Ecotoxicology and Ecophysiology, Kreuzlinger Str. 1, Rottenburg, Germany ABSTRACT- Even though, in recent years, there has been an increasing interest in the use of subcellular biomarkers for the assessment of potentially adverse effects of stressors on individual and population "health", reported variability of biochemical endpoints has raised occasional scepticism on the applicability of these endpoints as biomarkers in the field. This paper will address the variability of stress marker (hsp70) responses which, at the first look, seem to prevent their use in natural systems. The paper, however, will also show, how the sources for this variability can be identified and handled, even in the field. These sources of biomarker variability are of different origin: endogenous cycles (e.g. cycles of fertility in a freshwater snail), exogenous cycles (e.g. the diurnal or annual temperature cycle influencing central European fish or tropical chitons) or micro-evolutionary processes (e.g. the selection of insensitive phenotypes in two woodlice species) contribute to stress marker variability. Considering these effects, we should accept that some biomarkers, like hsp70, are monitoring the individual potential of an organism to respond adequately to the entirety of (proteotoxic) stressors actually affecting it. Nevertheless, it is hard to attribute distinct quantities of this stress action to particular stress factors (chemicals, parasites, heat) when they act together and, thus, it must be emphasized that hsp70 is a tool to monitor stress effects rather than exposure to distinct chemicals. Since effects, but not exposure, determine the integrity of biological systems, field variation of biomarkers of effect does not only reflect actual stress situations (and, therefore, enables us to assess the impact of a suit of stress factors in the environment) but may also indicate hot spots of susceptibility and vulnerability (caused by particular phases in e.g. ontogeny, reproduction, habitat features, etc) in time and space. Key words: biomarker variability, stress proteins, (a)biotic cycles, microevolution |
