title: Fluorescence imaging of microbe-containing particles shot from a two-stage Light-gas gun into an aerogel.
abstract: We have proposed an experiment (the Tanpopo mission) to capture microbes on the Japan Experimental Module of the International Space Station. An ultra low-density silica aerogel will be exposed to space for more than 1 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 an 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 ~8 km/s are expected to collide with the aerogel. To simulate these collisions, we shot Deinococcus radiodurans-containing Lucentite particles into the 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.
authors.affiliation: Department of Applied Life Sciences School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Sugino
authors.forename: Makoto
authors.initials: M
authors.lastname: Tabata
authors.forename: Kyoko
authors.initials: K
authors.lastname: Okudaira
authors.forename: Eichi
authors.initials: E
authors.lastname: Imai
authors.forename: Hajime
authors.initials: H
authors.lastname: Yano
authors.forename: Sunao
authors.initials: S
authors.lastname: Hasegawa
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Hikaru
authors.initials: H
authors.lastname: Yabuta
authors.forename: Kensei
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kawai
authors.forename: Hajime
authors.initials: H
authors.lastname: Mita
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Yokobori
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamagishi
mesh_terms: D052160:Benzothiazoles; D004269:DNA, Bacterial / Q000032:analysis*; D034301:Deinococcus / Q000235:genetics / Q000302:isolation & purification*; D003959:Diamines; D005118:Extraterrestrial Environment; D005782:Gels; D009930:Organic Chemicals; D010316:Particle Size; D011804:Quinolines; D012822:Silicon Dioxide / Q000032:analysis; D013050:Spectrometry, Fluorescence
chemical_list: D052160:Benzothiazoles; D004269:DNA, Bacterial; D003959:Diamines; D005782:Gels; D009930:Organic Chemicals; D011804:Quinolines; C098022:SYBR Green I; D012822:Silicon Dioxide
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