Search

Chemosynthetic organisms flourish around deep-sea hydrothermal vents where energy-rich fluids are emitted from metal sulfide chimneys. However, microbial life hosted in mineral assemblages in extinct chimneys lacking fluid venting remains largely unknown. The interior of extinct chimneys remains anoxic where the percolation of oxygenated seawater is limited within tightly packed metal sulfide grains. Given the scarcity of photosynthetic organics in deep seawater, anaerobic microbes might inhabit the grain boundaries energetically depending on substrates derived from rock-water interactions. In this study, we reported ultra-small cells directly visualized in grain boundaries of CuFeS2 inside an extinct metal sulfide chimney from the southern Mariana Trough. Nanoscale solid analyses reveal that ultra-small cells are coated with Cu2O nanocrystals in grain boundaries enriched with C, N, and P. In situ spectroscopic and spectrometric characterizations demonstrate the distribution of organics with amide groups and a large molecular organic compound in the grain boundaries. We inferred that the ultra-small cells are anaerobes because of the fast dissolution of Cu2O nanocrystals in oxygenated solution. This Cu2O property also excludes the possibility of microbial contamination from ambient seawater during sampling. It is shown by 16S rRNA gene sequence analysis that the chimney interior is dominated by Pacearchaeota known to have anaerobic metabolisms and ultra-small cells. Our results support the potential existence of photosynthesis-independent microbial ecosystems in grain boundaries in submarine metal sulfides deposits on the early Earth.

A dense magnesium iron silicate polymorph with a structure intermediate between olivine, ringwoodite, and wadsleyite was theoretically predicted about four decades ago. As this group of minerals constitute the major component of shocked meteorites, constraining their transitional forms and behaviour is of potential importance for understanding impact events on their parent bodies. Here we use high-resolution transmission electron microscopy techniques and single-crystal X-ray diffraction analyses to identify naturally occurring examples of this mineral – recently named poirierite – in shocked chondritic meteorites. We observe nanoscale lamellar poirierite topotactically intergrown within wadsleyite, and additionally within ringwoodite as recently reported. Our results confirm the intermediate structure of poirierite and suggest it might be a relay point in the shear transformations between its polymorphs. We propose that poirierite formed during rapid decompression at relatively low temperature in retrograde shock metamorphism of the meteorites., 宇宙から飛来した隕石から新鉱物ポワリエライトを発見 --小天体の衝突過程、地球内部の変化等を探る重要な鍵に--. 京都大学プレスリリース. 2021-01-25.

第8回極域科学シンポジウム/個別セッション：[OA] 南極隕石 / はやぶさ12月5日（火）国立極地研究所 1階交流アトリウムThe Eighth Symposium on Polar Science/Ordinary sessions: [OA] Antarctic meteorites / HayabusaTue. 5 Dec./Entrance Hall (1st floor), National Institute of Polar Research

A new approach at the transcriptional level was applied to lactate-based polyester production. Four sigma factor disruptants, Delta rpoN, Delta rpoS, Delta fliA and Delta fecl, of Escherichia con were used as hosts for poly(lactate-co-3-hydroxybutyrate) production from glucose. Among them, Delta rpoN caused dual positive effects of polymer production, enhanced cellular content and lactate fraction.

第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日（木） 国立極地研究所 2階大会議室前フロア

第30回極域地学シンポジウム「極域から探る固体地球ダイナミクス」ポスター発表

第30回極域地学シンポジウム「極域から探る固体地球ダイナミクス」ポスター発表