Biodevices for Space Research.

This review focuses on the realisation of optical sensors able to monitor the effect of complex space radiation on biological components, based on the biosensor concept. A biosensor is a device that can reveal a biochemical variable using a biological component interfaced with a transducer. It issues an electric signal which is easy to process, depending on the analysed variable. Biosensors are useful to study the effect of stress conditions on living organisms. One of the goals of this research was to develop two types of biosensors able to monitor directly the response of oxygenic photosynthetic organisms to radiation present in space in view of their importance for future space colonization. In ground experiments and in balloon stratosphere flights, the photosynthetic process has been analysed at the level of photosystem II (PSII), the supramolecular pigment-protein complex in the chloroplast which catalyses the light-induced transfer of electrons from water to plastoquinone; PSII splits water into molecular oxygen, protons and electrons, thereby sustaining an aerobic atmosphere on Earth and providing the reducing equivalents necessary to fix carbon dioxide to organic molecules, creating biomass, food and fuel. The results indicated that presence of space radiation in the dark has a synergistic effect on photosystem II activity, suggesting that PSII D1 protein turnover may be involved in resistance to space stress. The resistance of the tested microorganisms to space stress seems to be related to their position on the evolutive scale of photosynthesis. The present studies allow to establish a regular and reliable correlation between measured physical characteristics of space radiation and biological radiation effect. [ABSTRACT FROM AUTHOR]