[B-AO01_28PO1] Astrobiology: Origins, Evolution, Distribution of Life

[BAO01-P07] DNA蛍光色素を用いたエアロゲルに衝突した微生物の検出

*河口 優子¹、杉野 朋弘²、田端 誠¹、奥平 恭子³、今井 栄一⁴、矢野 創¹、長谷川 直¹、薮田 ひかる⁵、小林 憲正⁶、河合 秀幸⁷、三田 肇⁸、橋本 博文¹、横堀 伸一²、山岸 明彦² (1.宇宙航空研究開発機構宇宙科学研究所、2.東京薬科大学、3.会津大学、4.長岡技術科学大学、5.大阪大学、6.横浜国立大学、7.千葉大学、8.福岡工業大学)

キーワード：Aerogel, Space experiment, Hypervelocity impact experiment, DNA-specific fluorescence dye

We previously proposed an experiment (the Tanpopo mission) to capture microbes and organic compounds on the Japan Experimental Module of the International Space Station. An ultra low-density silica aerogel will be exposed to space for one year. After retrieving the aerogel, particle tracks and particles found in it will be visualized by fluorescence microscopy after staining it with a DNA-specific fluorescence dye. In preparation for this study, we simulated particle trapping in the aerogel so that methods could be developed to visualize the particles and their tracks. During the Tanpopo mission, particles that have an orbital velocity of about 8 km/s are expected to collide with the aerogel. To simulate these collisions, we shot Deinococcus radiodurans-containing Lucentite particles into an aerogel from a two-stage light-gas gun (acceleration 4.2 km/s). The shapes of the captured particles and their tracks and entrance holes were recorded with a microscope/camera system for further analysis. The size distribution of the captured particles was smaller than the original distribution, suggesting that the particles had fragmented. We were able to distinguish between microbial DNA and inorganic compounds after staining the aerogel with the DNA-specific fluorescence dye SYBR green I as the fluorescence of the stained DNA and the autofluorescence of the inorganic particles decay at different rates. The developed methods are suitable to determine if microbes exist at the International Space Station altitude.
Keywords: Aerogel, Space experiment, Hypervelocity impact experiment, DNA-specific fluorescence dye.