9 October 2007 VUV-UV absorption spectroscopy of DNA and UV screens suggests strategies for UV resistance during evolution and space travel
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Abstract
Early life on Earth had to cope with harsh conditions, including full spectrum solar UV. Since DNA absorbs in the highly energetic UV-C and VUV, solar irradiation was likely an obstacle to the expansion of life on Earth, until biological mechanisms evolved to cope with UV liability (including the biosynthesis of UV screens) and ozone (derived from oxygen produced by photosynthesis) accumulated in the stratosphere. In an effort to better understand the UV liability of DNA, we used synchrotron light to measure VUV-UV absorption spectra (125-340 nm) for DNA and its components (oligonucleotides and mononucleotides). We also measured VUV-UV absorption spectra for potential and known UV screens, including amino acids, proteins, amines (including polyamines), scytonemin, mycosporine-like amino acids, β- carotene, melanin and flavonoids. Among these, flavonoids seem remarkably suited to protecting DNA in the VUV-UV. Flavonoids accumulate in seed coats, where they confer resistance to monochromatic UV (254 nm) and polychromatic UV (200-400 nm). We discuss these findings in relation to the origin and evolution of life and its potential dispersal through space.
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Andreja Zalar, David Tepfer, Søren V. Hoffmann, Albert Kollmann, Sydney Leach, "VUV-UV absorption spectroscopy of DNA and UV screens suggests strategies for UV resistance during evolution and space travel", Proc. SPIE 6694, Instruments, Methods, and Missions for Astrobiology X, 66940U (9 October 2007); doi: 10.1117/12.733699; https://doi.org/10.1117/12.733699
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