Patterns of gene content and co-occurrence constrain the evolutionary path toward animal association in Candidate Phyla Radiation bacteria

Jaffe, A. L.*; Thomas, A. D.*; He, C.*; Keren, R.*; Valentin-Alvarado, L. E.*; Munk, P.*; Bouma-Gregson, K.*; Farag, I. F.*; 天野 由記; Sachdeva, R.*; et al.

mBio, 12(4), p.e00521-21_1 - e00521-21_21, 2021/08

https://doi.org/10.1128/mBio.00521-21

Candidate Phyla Radiation (CPR) bacteria are small, likely episymbiotic organisms found across Earth's ecosystems. Despite their prevalence, the distribution of CPR lineages across habitats and the genomic signatures of transitions amongst these habitats remain unclear. Hear, we expand the genome inventory for Absconditabacteria (SR1), Gracilibacteria, and Saccharibacteria (TM7), CPR bacteria known to occur in both animal-associated and environmental microbiomes, and investigate variation in gene content with habitat of origin. By overlaying phylogeny with habitat information, we show that bacteria from these three lineages have undergone multiple transitions from environmental habitats into animal microbiomes. Based on co-occurrence analyses of hundreds of metagenomes, we extend the prior suggestion that certain TM7 have broad bacterial host ranges and constrain possible host relationships for SR1 and Gracilibacteria. Full-proteome analyses show that animal-associated TM7 have smaller gene repertoires than their environmental counterparts and are enriched in numerous protein families, including those likely functioning in amino acid metabolism, phage defense, and detoxification of peroxide. In contrast, some freshwater TM7 encodea putative rhodopsin. For protein families exhibiting the clearest patterns of differential habitat distribution, we compared protein and species phylogenies to estimate the incidence of lateral gene transfer and genomic loss occurring over the species tree. These analyses suggest that habitat transitions were likely not accompanied by large transfer or loss events, but rather were associated with continuous proteome remodeling. Thus, we speculate that CPR habitat transitions were driven largely by availability of suitable host taxa, and were reinforced by acquisition and loss of some capacities.

Pedestal conditions for small ELM regimes in tokamaks

大山 直幸; Gohil, P.*; Horton, L. D.*; Hubbard, A. E.*; Hughes, J. W.*; 鎌田 裕; 神谷 健作; Leonard, A. W.*; Loarte, A.*; Maingi, R.*; et al.

Plasma Physics and Controlled Fusion, 48(5A), p.A171 - A181, 2006/05

https://doi.org/10.1088/0741-3335/48/5A/S16

Type I ELMを伴うHモード運転はITERの標準運転シナリオとして考えられているが、type I ELMによる瞬間的な熱・粒子束によるダイバータの損耗が懸念されている。近年、世界中のトカマク装置で振幅の小さなELMを伴うHモード放電の研究が進展しており、幾つかの新しい運転領域が発見されている。本論文は、Alcator C-Mod, ASDEX Upgrade, DIII-D, JET, JFT-2M, JT-60U and NSTX各装置で得られている小振幅ELM放電について、ペデスタル特性の観点から運転領域,周辺揺動,周辺部MHD安定性について比較・要約した結果を報告している。また、ITERプラズマへの適用に向けた研究課題についても議論している。

Laboratory work to examine microbial effects on redox and quantification of the effects of microbiological perturbations on the geological disposal of HLW (TRU)

吉田 英一; 濱 克宏; West, J. M.*; Bateman, K.*; Milodowski, A. E.*; Baker, S. J.*; Coombs, P.*; Hards, V. L.*; Spiro, B.*; Wetton, P. D.*

JNC TJ7400 99-013, 68 Pages, 1999/07

JNC-TJ7400-99-013.pdf:3.15MB

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