一些科學(xué)家相信,，微生物（如圖）能夠在行星之間傳遞——當(dāng)一顆隕星與另一顆天體碰撞后，前者爆炸所產(chǎn)生的巖石碎片最后會落到后者的表面,。
據(jù)美國《科學(xué)》雜志在線報道,，如今，一個國際研究小組在原則上證實了這一假設(shè)——這些“天外來客”能夠在碰撞過程中幸免于難,?？茖W(xué)家用炸藥轟擊包含有微生物的地球巖石，旨在模擬隕星在空中爆炸時的景象,。結(jié)果表明,，盡管一些細(xì)菌因此死掉，但仍有一些細(xì)菌活了下來,。研究人員在2月份出版的《天體生物學(xué)》（Astrobiology）雜志上報告了這一發(fā)現(xiàn),。（來源：科學(xué)時報 群芳）
生物谷推薦原始出處：
（Astrobiology），doi:10.1089/ast.2007.0134,，Gerda Horneck, Natalia A. Artemieva
Microbial Rock Inhabitants Survive Hypervelocity Impacts on Mars-Like Host Planets: First Phase of Lithopanspermia Experimentally Tested
Gerda Horneck, Dieter Stoffler, Sieglinde Ott, Ulrich Hornemann, Charles S. Cockell, Ralf Moeller, Cornelia Meyer, Jean-Pierre de Vera, Jorg Fritz, Sara Schade, Natalia A. Artemieva.
ABSTRACT
The scenario of lithopanspermia describes the viable transport of microorganisms via meteorites. To test the first step of lithopanspermia, i.e., the impact ejection from a planet, systematic shock recovery experiments within a pressure range observed in martian meteorites (5–50 GPa) were performed with dry layers of microorganisms (spores of Bacillus subtilis, cells of the endolithic cyanobacterium Chroococcidiopsis, and thalli and ascocarps of the lichen Xanthoria elegans) sandwiched between gabbro discs (martian analogue rock). Actual shock pressures were determined by refractive index measurements and Raman spectroscopy, and shock temperature profiles were calculated. Pressure-effect curves were constructed for survival of B. subtilis spores and Chroococcidiopsis cells from the number of colony-forming units, and for vitality of the photobiont and mycobiont of Xanthoria elegans from confocal laser scanning microscopy after live/dead staining (FUN-I). A vital launch window for the transport of rock-colonizing microorganisms from a Mars-like planet was inferred, which encompasses shock pressures in the range of 5 to about 40 GPa for the bacterial endospores and the lichens, and a more limited shock pressure range for the cyanobacterium (from 5–10 GPa). The results support concepts of viable impact ejections from Mars-like planets and the possibility of reseeding early Earth after asteroid cataclysms. Astrobiology 8, 17–44.
