第6回海洋・極限環境生物圏 領域セミナー
開催場所:Main Lecture Hall, JAMSTEC Headquarter Area at Yokosuka


・Dr. Hiroshi Kitazato (Biogeos, JAMSTEC): Brief introduction

・Dr. Yoshinori Takano (Biogeos, JAMSTEC)
Title: A linkage between past and present microbes in sub-seafloor

Since discovery of the deep biosphere in the 1990’s, comprehensive knowledge of prokaryotes have created a new area of scientific investigation because deep-sea sediments represent a novel biosphere comprising global carbon cycle with phylogenic lineages of domain Archaea and Bacteria. Recent sub-seafloor studies among Integrated Ocean Drilling Program (IODP) revealed that past organic matter content in the sediment could represent a crucial factor in the growth and reproduction of heterotrophic sub-seafloor Archaea. As the putative predominant archaea are viable but non-cultureable and on-shore laboratory studies remain problematic, we are developing a new organic geochemical tool to compensate the limitation toward a next milestone of deep biosphere studies.

・Dr. Hiroyuki Imachi (Biogeos, JAMSTEC)
Title: Challenge for previously uncultivated subseafloor methanogens potentially supporting vast subseafloor methane pools

Recent cultivation-independent molecular studies showed that phylogenetically diverse microbes are present in marine subsurface environments. However, these microbes, especially for major microbial components and key-biogeochemical players including methanogens, have been highly resistant to in vitro cultivation. For the successful cultivation of these recalcitrant marine subsurface microbes, I used a continuous-flow bioreactor system that has been often used for treatment of municipal wastewater. Using the bioreactor, I have successfully made a methanogenic microbial community from marine subsurface sediment after 1 year of the reactor operation. The microbial community contained phylogenetically diverse microbes including uncultured methanogens.

・Prof. Dr. Judith McKenzie (ETH, Switzerland)
Title: Dolomite Formation in Time and Space

Since its discovery in 1791, dolomite, the mineral and the rock, has stimulated much research. Despite a profusion of hypotheses and idealized models for dolomite formation, the specific conditions for its origin have remained and enigma. Recently, a new geomicrobiological approach has been applied to the study of modern and ancient dolomite offering an actualistic solution for the long-standing Dolomite problem.

・Free Discussions in terms of deep subsurface biosphere research

第5回海洋・極限環境生物圏 領域セミナー
講演者:Dr. Duhgal J. Lindsay(海洋生物多様性プログラム、深海生態系研究チーム)

(Development of a system to survey planktonic diversity and ecosystem functioning on a global scale)

In this talk I will explain the background behind why such a system is necessary as well as the steps that have already been taken towards the development of such a system. There will be an introduction to cutting edge survey techniques using imaging technology, DNA barcoding and traditional taxonomic methods, real data from Antarctica, and a vision towards the development of new infrastructure to realize the goal of the next phase of the Census of Marine Life.

第4回海洋・極限環境生物圏 領域セミナー
開催日時: 7月24日(金) 16:00〜17:30
開催場所: 横須賀本部本館
講演者:高木 善弘 博士(深海・地殻内生物圏研究プログラム、環境メタゲノム研究チーム)


我々は、これまでに極限微生物としてBacillus halodurans C-125、それに続く2株のBacillus属類縁細菌のゲノム解析を 行ってきた。現在、ここで得た技術や情報を基礎に、深海に生息す る微生物の進化やその能力について研究を行っている。我々は、い つも“ゲノムから何を知ることできるのか?”、“ゲノム全体をみ なければ理解できないこととは何であるか?”に留意しています。 最近、熱水孔に生息するイプシロンプロテオバクテリアゲノムから N-結合型糖鎖付加遺伝子を発見から、深海化学合成系の共生システ ムにおける糖鎖分子を介したコミュニケーションの研究へと発展し てます。また、シロウリガイ共生細菌ゲノム比較により、ゲノム縮 小プロセスについて一つの仮説を導く事ができました。今回のセミ ナーにおいて、これら興味深い極限環境生物圏における微生物のゲ ノム解析について話します。

Title: Microbial genome in extremobiosphere
We have been investigating on genome analyses of Extremophiles, namely Bacillus halodurans C-125 and two Bacillus related strains. Since then, based on the technique and information of genome analysis, we are studying on activities and evolution of deep-sea microorganisms. Our studies usually concentrated on what we can know or understand through whole genome analysis. Recently, we found genes involving N-linked glycosylation in the genome of Epsilonproteobacteria, which develops into a study on communication via carbohydrate chains between bacteria and invertebrate in deep-sea chemosynthetic symbioses. We also formulated a hypothesis about genome reduction process upon genome comparison of two deep-sea Calyptogena symbionts. In this seminar, I describe an interesting genome research in extremobiosphere.

第3回海洋・極限環境生物圏 領域セミナー
開催日時:6月15日(月)16:00 〜 17:30
開催場所:横須賀本部1階 大講義室
講演者:Dr. Florence Padallion (Marine Biodiversity Program)

Title:Dispersal and colonization strategies in polychaete species inhabiting deep-sea chemosynthetic environments

第2回海洋・極限環境生物圏 領域セミナー
開催場所:横須賀本部 本館1階大講義室
講演者 :力石 嘉人(海洋環境・生物圏変遷過程研究プログラム)

演 題 :有機化合物の化合物レベル安定同位体比解析が導く生物地球化学研究の新展開

GC/IRMS(ガスクロマトグラフ/同位体比質量分析計)を用いた有機化合物の分子レベル安定同位体比分析は,生物試料や環境試料に含まれる多種多様な有機化合物の安定同位体比(D/H, 13C/12C, 15N/14N, 18O/16Oなど)を化合物レベ ルで測定することができる。 今日のセミナーでは、この手法の簡単なレビューを行い、また、応用例の一つとして、アミノ酸の窒素同位体比を用いた生物の栄養段階推定法について、最近我々の研究グループで得られている知見を中心に発表する。

Title: Compound-specific stable isotope analysis of organic compounds and its application to biogeochemistry
One of the most powerful tools in the molecular isotope studies is compound-specific isotope analysis (CSIA) by gas chromatograph/isotope ratio mass spectrometer (GC/IRMS), which allows a rapid and precise determination of stable carbon, nitrogen, and hydrogen (and oxygen) isotopic compositions of individual compounds even in complex mixture of components.In this seminar, I will review this tool briefly and show a recent application to ecological studies: estimation of the trophic level of organisms in food webs.

第1回海洋・極限環境生物圏 領域セミナー
開催場所:横須賀本部 本館1階大講義室

1.講演者:布浦 拓郎 博士
演題 :海溝生命圏の発見? (Discovery of possible “Trench Biosphere” )

2.講演者:長野 由梨子 博士
演題 :深海環境における真菌研究
真菌は地球上の多くの生態系において主要なバイオマスとして存 在し、その生態や生理機能は実に様々である。近年、極限環境であ る深海環境においても真菌の存在が認められつつあるが、その分布 や多様性の多くは謎のままであった。しかし、分子生物学的手法を 用いた研究により深海底泥には新規性の高い真菌、特に原始的な性 質をもった進化上重要なグループに属するものが多く存在する事が 明らかとなってきた。さらに、我々のグループでは、深海由来真菌 の応用研究にも着手しており、基盤研究から応用研究への展開も進 めていきたい。

Title: Studies on fungi in deep-sea environments
Fungi are one of the most important components in ecosystems and they occupy a wide variety of environments by virtue of their highly versatile physiology function. Although the presence of fungi in deep- sea environments has started to be recognized, its distribution and diversity are still largely unknown. Environmental gene library analyses of deep-sea sediments have recently demonstrated the presence of diverse highly novel fungi, including new taxonomic groups that may be relevant to the early evolution of fungi. Our research team has also started to work on deep-sea delivered fungi for application use. We believe that fungi in deep-sea environments hold great potential for both science and industry.

3.講演者:土屋 正史 博士
演題 :貧酸素環境の底生有孔虫は単細胞真核生物の進化のモデルとなる?
 貧酸素環境下での底生有孔虫Virgulinella fragilisの生存 戦略を理解するために,細胞内の内生生物の種類と起源を分子系統 解析と電子顕微鏡(TEM, SEM)から推測した。貧酸素環境で 底生有孔虫は,共生生物を介して生存していると推測されている。 本研究では,V. fragilisに存在する2種類の内生生物 (バクテリアと盗葉緑体)について解析を行い,宿主有孔虫と内生 生物間の関係から貧酸素環境における生存にどのように関わるかを 推測した。

Title: Molecular characterization of benthic foraminifer Virgulinella fragilis to understand the survival strategy in oxygen-depleted environment)
Molecular phylogenetic analyses and ultrastructural observation were conducted in order to understand the survival strategy of Virgulinella fragilis, a benthic foraminifer restricted to dysoxic environments. Many benthic foraminifers can persist in sediment in dysoxic environments. Some of them probably live in symbiosis with bacteria that can denitrificate and also putatively oxidize sulfide. Observations of endosymbiotic bacteria and kleptoplasts in V. fragilis may allow the foraminifer to survive in low oxygen environments, which reveal the important role of speciation via endosymbiosi.