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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Molecular evidence for the antiquity of group I introns inter-rupting transfer RNA genes in cyanobacteria / Molecular Bestätigung des hohes Alters von introns in Cyanobakterien

Fewer, David 31 January 2002 (has links)
No description available.
2

Impact shocked rocks as protective habitats on an anoxic early Earth

Bryce, C.C., Horneck, G., Rabbow, E., Edwards, Howell G.M., Cockell, C.S. 2014 May 1914 (has links)
No / On Earth, microorganisms living under intense ultraviolet (UV) radiation stress can adopt endolithic lifestyles, growing within cracks and pore spaces in rocks. Intense UV irradiation encountered by microbes leads to death and significant damage to biomolecules, which also severely diminishes the likelihood of detecting signatures of life. Here we show that porous rocks shocked by asteroid or comet impacts provide protection for phototrophs and their biomolecules during 22 months of UV radiation exposure outside the International Space Station. The UV spectrum used approximated the high-UV flux on the surface of planets lacking ozone shields such as the early Earth. These data provide a demonstration that endolithic habitats can provide a refugium from the worst-case UV radiation environments on young planets and an empirical refutation of the idea that early intense UV radiation fluxes would have prevented phototrophs without the ability to form microbial mats or produce UV protective pigments from colonizing the surface of early landmasses.

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