title: Survival of Deinococcus radiodurans against laboratory-simulated solar wind charged particles.
abstract: In this experimental study, cells of the radiation-resistant bacterium Deinococcus radiodurans were exposed to several different sources of radiation chosen to replicate the charged particles found in the solar wind. Naked cells or cells mixed with dust grains (basalt or sandstone) differing in elemental composition were exposed to electrons, protons, and ions to determine the probability of cell survival after irradiation. Doses necessary to reduce the viability of cell population to 10% (LD(10)) were determined under different experimental conditions. The results of this study indicate that low-energy particle radiation (2-4 keV), typically present in the slow component of the solar wind, had no effect on dehydrated cells, even if exposed at fluences only reached in more than 1000 years at Sun-Earth distance (1 AU). Higher-energy ions (200 keV) found in solar flares would inactivate 90% of exposed cells after several events in less than 1 year at 1 AU. When mixed with dust grains, LD(10) increases about 10-fold. These results show that, compared to the highly deleterious effects of UV radiation, solar wind charged particles are relatively benign, and organisms protected under grains from UV radiation would also be protected from the charged particles considered in this study.
authors: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil. igplima@gmail.com
authors: Ivan Gláucio
authors: IG
authors: Paulino-Lima
authors: Eduardo
authors: E
authors: Janot-Pacheco
authors: Douglas
authors: D
authors: Galante
authors: Charles
authors: C
authors: Cockell
authors: Karen
authors: K
authors: Olsson-Francis
authors: John Robert
authors: JR
authors: Brucato
authors: Giuseppe Antonio
authors: GA
authors: Baratta
authors: Giovanni
authors: G
authors: Strazzulla
authors: Tony
authors: T
authors: Merrigan
authors: Robert
authors: R
authors: McCullough
authors: Nigel
authors: N
authors: Mason
authors: Claudia
authors: C
authors: Lage
mesh_terms: D002244:Carbon; D003198:Computer Simulation; D034301:Deinococcus / Q000166:cytology* / Q000528:radiation effects* / Q000648:ultrastructure; D004583:Electrons; D007753:Laboratories; D050296:Microbial Viability / Q000528:radiation effects; D011522:Protons; D017640:Silicates / Q000737:chemistry; D013472:Sunlight; D014919:Wind
chemical_list: D011522:Protons; D017640:Silicates; C060346:basalt; D002244:Carbon