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Resistance of Arabidopsis thaliana seeds exposed to monochromatic and simulated solar polychromatic UV radiation: Preparation for the EXPOSE space missions to the International Space Station (ISS)

Abstract : Ultraviolet (UV) radiation has a strong impact on all known biological systems and it is considered as one of the main limitation factors for dispersal of life on Earth and beyond. In space, the full solar spectrum can be encountered, including the UV-A (315-365 nm), the UV-B (280-315 nm), and highly energetic UV-C (200-280 nm) and the VUV (<200 nm). Neither VUV nor UV-C reaches the surface of the present-day Earth, thanks to filtration by the stratospheric ozone layer. However, life on the early Earth had probably to cope with damaging short-wavelength solar UV. In an effort to better understand the UV viability of DNA, we studied VUV-UV absorption properties of DNA and its components (nucleotides). One of the strategies for resisting UV radiation is a biosynthesis of UV screens. By measuring VUV-UV absorption spectra, we estimated the protection capacities for some ubiquitous potential UV screens (proteins, amino acids, polyamines, tyramine and nucleotides, including ATP), as well as specialized UV screens, isolated from phylogenetically distinct groups of organisms (mycosporine-like amino acids (MAA), scytonemin, carotenoids, melanins and flavonoids). Flavonoids, the phenolic compounds in plants, seemed the best suited to provide efficient UV screening protection to DNA. Flavonoids accumulate in high concentration in plant seeds. The UV protective role of flavonoids was demonstrated in experiments in vivo, using Arabidopsis thaliana seeds, which exhibited exceptionally high resistance to monochromatic UV-C254 (up to 6 x 105 kJm-2), and simulated solar polychromatic UV200-400 (1.5 x 105 kJm-2) under simulated space vacuum and simulated Mars CO2 atmosphere. In order to further evaluate the resistance of seeds to the full spectrum of solar light and to test the plausibility of panspermia theory, we prepared the experiments for space missions EXPOSE carried out on the exterior of the International Space Station (ISS).
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Contributor : Andreja Zalar <>
Submitted on : Monday, July 26, 2021 - 4:18:14 PM
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Andreja Zalar. Resistance of Arabidopsis thaliana seeds exposed to monochromatic and simulated solar polychromatic UV radiation: Preparation for the EXPOSE space missions to the International Space Station (ISS). Vegetal Biology. Université de Versailles Saint Quentin en Yvelines (UVSQ), 2010. English. ⟨tel-03299728⟩

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