Survival Strategies Cannot Be Devised, They Do Exist Already: A Case Study on Lichens

Abstract

Lichens found the strategy to survive in a physiologically dormant dehydrated state. Like reverse micelles or ternary systems lipid, surfactant, protein systems used as models of membrane functions in biochemistry (Darszon et al. 1979; Strasser et al. 1992; Srivastava et al. 2000), so called low water systems. In the dehydrated state they become inactive, but extremely resistant to long term high and low temperatures, high salt and high light conditions. Traces of water (like in ternary lipid photo active protein complexes (Gruszecki et al. 1994) can activate these complexes, which however become sensitive to extreme temperatures and light intensities. We know that 1-6% of water v/v is enough to activate the dormant biochemical reactions of immobilized cells, photochemically active chlorophyll light harvesting complexes and photo-synthetic membranes of bacteria. Lichens seem to behave this way. Primary reactions as well as integral photosyn-thetic activities are detectable and distinguishable by measuring the fast fluorescence rise (Strasser 1978; Strasser et al. 1995). The JIP test equations allow calculations that estimate the activation of several photosynthetic parameters within a time range of second or sub-second. The immediate activation of photosynthetic functions upon adding water to dry lichens is shown in the present study.