BAO01-01

Room:105

Time:May 27 15:15-15:30

Understanding the generality of terrestrial life
YAMAGISHI, Akihiko1∗
1

Tokyo Univ. Pharm. Life Scie., Dep. Applied Life Scie.

We only know the life on the Earth. In this presentation I am going to evaluate the system especially genetic system of terrestrial
life. Water is needed for life to solubilize the molecules and especially important to maintain the structure of protein. Protein isneeded to almost all activity of life, especially catalytic activity that is carried by the protein called enzyme. All terrestrial livingorganism consists of (a) cell(s), surrounded by membrane. Membrane is maintained by the hydrophobic interaction driven by thehydrogen-bonding network between water molecules. Genetic information is used to form the structure of enzymes to induce
catalytic activity, forming the arrangement of amino acid residues. What are the necessities and what are the coincidences? I will
present some clues to the questions. These can be useful for searching for life in the Universe.
Keywords: Cell, Organic compounds, Cell membrane, Genetic material

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BAO01-02

Room:105

Time:May 27 15:30-16:00

Extremophiles under pressure: Integrating experimental and field studies at deep-sea hydrothermal vent sites
FOUSTOUKOS, Dionysis1∗ ; PEREZ-RODRIGUEZ, Ileana1 ; SIEVERT, Stefan M.2 ; SEEWALD, Jeffrey S.3 ;SYLVA, Sean P.3 ; RAWLS, Matthew1 ; MCNICHOL, Jesse2 ; THOMAS, Francois2
1
3

Geophysical Laboratory, Carnegie Institution of Washington, USA, 2 Biology, Woods Hole Oceanographic Institution, USA,
Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, USA

In the great depths of the Earth’s interior, forces capable of moving continents sculpt the seafloor and form volcanoes transferring materials and energy to the ocean. Seawater circulation within these magmatic provinces results in the development of
deep-sea hydrothermal vents that are often considered to resemble the conditions on early Earth. It is under these extreme conditions that, by a synergy of chemistry and biology, life thrives in the absence of light and sparse nutrients. Notably, anaerobic
chemolithoautotropic bacteria that inhabit these extreme environments tend to branch deeply in the tree of life, probably retaining
relics of early metabolic pathways.
Here, we present data from shipboard continuous-culturing incubations of hydrothermal vent fluids conducted during an R/V
Atlantis-ROV Jason/Medea expedition to the deep-sea vents sites (2500 m) at 9o 50’N East Pacific Rise (January of 2014). This
was accomplished through a multi-disciplinary and multi-institutional collaborative effort to collect; transfer and culture ventfluids from the diffuse flow sites, onboard the vessel under seafloor pressure conditions (250 atm). Experiments were designed to
study the cycling of N through the metabolic processes of denitrification and dissimilatory nitrate reduction to ammonia (DNRA)
under in-situ deep-sea vent temperature and pressure conditions.
In detail, we studied the growth/metabolism of nitrate-reducing microorganisms at mesophilic (30 ℃) and thermophilic (60℃) conditions at pressures ranging from 5 to 250 atm. A high pressure bioreactor was employed onboard the ship to allow
direct study of the biological functions of microorganisms collected from diffuse-flow vent fluids (Fig. 1). This experimental
approach facilitates continuous culture of microorganisms at temperatures ranging from 25 to 120 ℃ and pressures up to 680
atm. The system allows incubating microbial communities in medium enriched with dissolved gases, under aerobic or anaerobic
conditions, while permitting periodic sampling of the incubated organisms with minimal physical/chemical disturbance inside
the reactor.
Experiments conducted simulate the subsurface biosphere environment and the continuous mixing of seawater and hydrothermal fluids in the oceanic crust. Vent fluids were delivered to the bioreactor under high pressure and homogeneously mixed withaqueous media solution enriched in dissolved nitrate, hydrogen, and 13 C-labeled bicarbonate to facilitate the growth of nitratereducing chemolithoautotrophic bacteria. Two distinct sets of experiments were carried out for 356 and 100 hours. During
the course of the experiments we monitored the growth of deep-sea microbial communities by measuring cell density and theconcentrations of dissolved aqueous species directly involved in nitrate based metabolism, such as NO3 − , NH4 + , H2(aq) andH2 S(aq) . Subsamples were also collected for a number of shore based analyses to determine: i) the 15 N/14 N isotope compositionof NO3 − /NH4 + and constrain kinetic isotope effects associated with denitrification/DNRA; ii) to study the rates of autotrophic
carbon fixation by NanoSIMS; iii) to perform single cell genomics on the microbial populations grown in the bioreactor and (iv)
to isolate and characterize novel microorganisms from the communities established in these experiments. In short, experimental
results constrain the function and metabolic rates of the native denitrifying microbial communities residing at moderate temperature conditions (30 ℃), while DNRA metabolic pathways were identified for the populations residing at higher temperature
diffuse flow fluids (60 ℃).
Keywords: extremophiles, deep-sea hydrothermal vents, chemolithoautotropic bacteria, high pressure, continuous culture, nitratebased metabolism

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BAO01-03

Room:105

Time:May 27 16:15-16:30

Robustness of the thermophilicity of ancient organisms
BESSHO, Mizumo1∗ ; AKANUMA, Satoshi1 ; YOKOBORI, Shin-ichi1 ; YAMAGISHI, Akihiko1
1Dept. Applied Life Sci., Tokyo Univ. Pharm. Life Sci.

All of the modern organisms are thought to have evolved from a single common ancestor named Commonote (1). In order toinvestigate the environmental temperatures of the ancient organisms, we resurrected amino acid sequences of ancestral nucleoside
diphosphate kinases (NDKs) that might be hosted by the last common ancestors of Archaea and of Bacteria. The enzyme
catalyzes the transfer of a phosphate from a nucleoside triphosphate to a nucleoside diphosphate.The ancestor of NDK family isthought to have been possessed by the ancient organisms because most extant cells, from bacteria to human, contain the gene(s)that encode a member of this family of proteins. More importantly, the denaturation temperature of a NDK correlates well withthe optimal growth temperature of its host. Therefore, we can estimate the environmental temperature of the ancient organisms byreconstruction ancestral NDK’s amino acid sequences and characterizing their thermal stabilities. In our previous study (2), theancestral amino acid sequences of NDK were inferred from two phylogenetic trees with different topologies using a maximum
likelihood program. The sequences were then reconstructed and characterized. From thermal denaturation experiments of thereconstructed enzymes, we estimated that the common ancestors of Archaea and of Bacteria lived at 81-97 ℃ and 80-94 ℃,
respectively. The Commonote was also likely to be a (hyper)thermophile that lived at a temperature above 75 ℃. However, acriticism for our conclusion is that the ancestral sequences have been inferred with an assumption that the amino acid composition
has been constant through evolutionary time. Gouy and coworkers (3) predicted the amino acid sequences of ancestral proteinsusing a Bayesian method that does not assume the constant evolutionary process through time. They estimated the optimal
environmental temperature of the ancestral organisms from the amino acid composition of seven amino acid types: leucine,isoleucine, valine, tyrosine, tryptophan, arginine, and glutamate. Based on the analysis, they suggested that the archaeal andbacterial ancestors were thermophilic but the Commonote was not a thermophilic organism. In this study, we re-inferred ancestral
NDK sequences using the same Bayesian program. The ancestral NDK sequences were inferred from two phylogenetic trees.
One tree was built without constraints and the other with the constraint that Archaea and Bacteria each represent a monophyletic
group. The gene encoding the ancestral NDK sequences were synthesized, expressed in Escherichia coli , and then the ancestral
NDKs were purified. Thermal denaturation measurements showed that the newly inferred ancestral NDK sequences are also
extremely thermally stable. Therefore, our conclusion of the (hyper)thermophilic ancestry is robust even if the ancestral aminoacid sequences were inferred without the assumption that the amino acid composition has been constant over evolution.
(1) Yamagishi et al. In Thermophiles: the keys to molecular evolution and the origin of life? (1998), pp287-295.
(2) Akanuma et al. Proc. Natl. Acad. Sci. USA (2013)110, 11067-11072(3) Boussau et al. Nature (2008)456, 942-947

Keywords: resurrection of ancestral proteins, Commonote, nucleoside diphosphate kinase, hyperthermophile

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BAO01-04

Room:105

Time:May 27 16:30-16:45

Origin of Eukarya based on phylogenetic trees of aminoacyl-tRNA synthetase
FURUKAWA, Ryutaro1∗ ; YOKOBORI, Shin-ichi2 ; YAMAGISHI, Akihiko2
1

Grad. sch. life sci., Tokyo Univ. of Pharm. life sci., 2 Sch. life sci., Tokyo Univ. of Pharm. life sci.

Woese et al. (1990; PNAS 87:4576-4579) classified all extant organisms into three domains based on the phylogenetic analysisof 16S/18S rRNA. Phylogenetic relationship of these three domains, especially the phylogenetic position of Eukarya has beenargued. Besides the three domain hypothesis, the two domain hypothesis has been proposed, where Eukurya are included inArchaea. With recent increase of genome sequences, phylogenetic analayses of all extant organism using concatenate alignment of universal conserved genes supported the two domain hypothesis (Guy & Ettema 2011; Trends Microbiol. 19:580-587,
Williams et al. 2012; Proc. Biol. Sci. 279:4870-4879, Williams et al. 2013; Nature 504:231-236, Willams & Martin Embley
2014;Genome Biol. Evol. 6:474-481). However, the closest archaeal species of Eukarya may be more than one in other analyses (Thiergart et al. 2012; Genome Biol. Evol. 4:466-485, Rochette et al. 2014; Mol. Biol. Evol. 31:832-845). Thus, theorigin of Eukarya is uncertain. In this study, we performed molecular phylogenetic analyses of 23 aminoacyl-tRNA synthetases(ARSs), and discussed phylogenetic relationship of all extant organisms. Clarifying evolutionary pathways of ARSs may extend
our fundamental understanding of early evolution of life. Organellar ARS traced various evolutionary routes different from cytoplasm ARS. Understanding their routes may clarify the origin of organellar and horizontal gene transfer during evolution of
Eukarya. Especially, we focused on the phylogenetic position and eukaryal cytoplasmic ARS. Amino acid sequence data of 23
ARSs (117 species: 56 Bacteria: 23 Archaea: 38 Eukarya) were collected. The ARS gene trees were reconstructed by using
the maximum likelihood method (RAxML) and the Bayesian method (PhyloBayes). The root of the individual gene tree wasinferred from composite tree of several ARSs. Cytoplasm ARSs in 13 trees (LeuRS, GluRS, TrpRS, CysRS, AspRS, GlyRS α2
type, SerRS, PheRS α subunit, PheRS β subunit, IleRS, ValRS, Class II LysRS, ThrRS) of 23 trees showed monophyly, however,
the other 7 trees showed polyphyly (AlaRS, ArgRS, HisRS, MetRS, ProRS, TyrRS, AsnRS). Cytoplasmic ARS is absent in 2
trees of 3 ARSs (Class I LysRS, GlyRS α2 β 2 type, GlnRS) and is sister group of bacterial group in GlnRS tree. 9 monophyletic
cytoplasm ARSs are ingroup of Archaea in 9 trees and 4 monophyletic cytoplasmic ARSs are ingroup of Bacteria in 4 trees. 7
polyphyletic cytoplasmic ARSs are also ingroups of Archaea and Bacteria. These results support the two domain hypothesis. 3
monophyletic cytoplasmic ARSs are closest to TACK superphylum in Archaea and another 3 monophyletic cytoplasmic ARSs
is closest to Euryarchaeota in Archaea. The closest species of monophyletic cytoplasmic ARSs in 9 trees showed that Eukarya
derived from both TACK superphylum and Euryarchaeota and suggest that the ancestor of Eukarya originated from the fusion
between ancestor of TACK superphylum and ancestor of Euryarchaeota. 4 monophyletic cytoplasm ARSs derived from bacteria
are closest to different bacterial species, which showed that independent lateral gene transfer occurred from bacterial genome
to the genome of Eukaryal ancestor and transferred genes replaced the cytoplasm ARS in the genome of Eukaryal ancestor.
Furthermore, 7 polyphyletic cytoplasmic ARSs showed that independent lateral gene transfer from Archaea or Bacteria occurred
during evolution of Eukarya and the genes replaced the cytoplasm ARS. Finally, We propose that the ancestor of Eukarya is fusedorganism between ancestor of TACK superphylum and ancestor of Euryarchaeota and lateral gene transfer of various bacteria
from different lineages have been contributed the formation of Eukaryal cells.
Keywords: phylogenetic analysis, aminoacyl tRNA synthetase, early evolution, origin of Eukarya

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BAO01-05

Room:105

Time:May 27 16:45-17:15

The First Report of the Tanpopo Mission after Its Arrival to the International Space Station
KAWAGUCHI, Yuko1∗ ; YANO, Hajime1 ; HASHIMOTO, Hirofumi1 ; YOKOBORI, Shin-ichi2 ; IMAI, Eiichi3 ;MITA, Hajime4 ; KAWAI, Hideyuko5 ; YABUTA, Hikaru6 ; TOMITA-YOKOTANI, Kaori7 ; NAKAGAWA, Kazumichi8 ;KOBAYASHI, Kensei9 ; OKUDAIRA, Kyoko10 ; TABATA, Makoto5 ; HIGASHIDE, Masumi1 ; HAYASHI, Hironobu11 ;SASAKI, Satishi12 ; KEBUKAWA, Yoko9 ; ISHIBASHI, Yukihiko13 ; YAMAGISHI, Akihiko2
1

ISAS/JAXA, 2 Sch. Life Sci., Tokyo Univ., Pharm., Life Sci., 3 Nagaoka Univ., of Tech.,, 4 Fukuoka Inst., of Tech.,, 5 Chiba
Univ.,, 6 Osaka Univ.,, 7 Univ., of Tukuba,, 8 Kobe Univ.,, 9 Yokohama Natl. Univ.,, 10 Univ., Aizu, 11 Tokyo Univ., Tech.,, 12 Tokyo
Insti., Tech.,, 13 Kyusyu Univ.,
To investigate the panspermia hypothesis and chemical evolution, The Tanpopo mission has been developed as Japan’s first
astrobiology-drivenl space experiments since 2007 (Yamagishi et al., 2009). This “Tanpopo” mission is launched this spring andit will be likely to start its first-year exposure on the ExHAM pallet onboard the Kibo Exposed Facility of International Space
Station (ISS) by the time conference will be held.
The Tanpopo mission is composed of two main experimental apparatus: capture panels and exposure panels. Both will be
prepared inside the Kibo module and exposed via airlock with its robot arm up to the maximum of 4 years. The capture panels
are to intact capture micrometeoroids, space debris and possible terrestrial aerosols uplifted to the ISS orbit by the world’s lowest
density silica aerogels exposed to space. If the Tanpopo succeeds to capture terrestrial microbes embedded in the aerosol particles
in the aerogel capture panels, it will push the upper limit of existing altitude for terrestrial microbes from the current record of
77 km to 400 km from the ground.
We also test both the survivability of some terrestrial microbes and the chemical alteration of astronomical analog organic
compounds in the near Earth space environment. For the former, we emphasize on the importance of cell-aggregates, whose
concept is known as “masapansperimia” (Kawaguchi et al., 2013), as the ark for interplanetary transfer of microbes
It is planned that the first samples of both panels will be retrieved back to the Earth in mid-2016, for post-flight analysis initiallyat ISAS and then at laboratories nationwide by the Tanpopo Team members.
References
Yamagishi et al., 2009, Trans. JSASS Space Tech. Japan, 7, ists26 (2009), pp. Tk 49-55.
Kawaguchi et al., 2013, Origins of Life and Evolution in Biospheres, 43, 411?428.

Keywords: space experiment, ISS, panspermia hypothesisi, chemical evolution

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BAO01-06

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Time:May 27 17:15-17:30

Phosphorus and iron cycles during early diagenesis of sediments under anoxic water massin a meromictic Lake Kai-ike
IIDA, Hajime1∗ ; YAMAGUCHI, Kosei E.2 ; OGURI, Kazumasa3
1

Toho University, 2 Toho University& NASA Astrobiology Institute, 3 JAMSTEC

A meromictic lake Kai-ike is located on the northeastern edge of Kami-koshiki island, Japan. Permanent density stratification
develops due to seawater infiltration through a gravel bar separating the lake from the ocean. The oxygenated surface water
overlays a stagnant, saline, and anoxic deep water containing hydrogen sulfide. Purple sulfur bacteria (Chromatium sp. ) inhabit
the chemocline at 4.5m depth. At the lake bottom, green sulfur bacteria form microbial mat-like structures (Nakajima et al.,2003). Such environment can be regarded as a model for the past anoxic ocean, such as during Oceanic Anoxic Events (Oguri etal., 2003).
We focused on the early diagenesis of phosphorus and iron in the lake. Phosphorus is a bio-essential element and a limiting
nutrient for primary production in the ocean on geological time scales. Biogeochemical processes during early diagenesis in sediments play important roles in controlling oceanic P budget, because P fluxes to and from the sediments depend on redox state of
the overlying water. Therefore, it is of great importance to understand early diagenetic geochemical behaviors of P in sediments
overlain by, for example, oxic, anoxic, and sulfidic (euxinic) water. In this study, we applied sequential extraction procedures toinvestigate geochemical behaviors of P and Fe in the surface sediments overlain by sulfidic water of the Lake Kai-ike.
A 25 cm-long KAI4 sediment core (Yamaguchi et al., 2010) was used for two sequential extraction methods. SEDEX method(Ruttenberg, 1992) was used for partitioning phosphorus-bearing species into Pabs (absorbed), PF e (iron-bound), Pauth (authigenic), Pdet (detrital), and Porg (organic). Iron-bearing species were also divided into FeHCl (dissolved in HCl), Fecarb(carbonate), Feox (oxide), Femag (magnetite), Fepy (pyrite), and Feresi (residue), following Poulton et al. (2005).
Main phosphorus-bearing form was found to be Porg . Its content sharply decreases with increasing depth near the sedimentsurface. Little precipitation of Fe-hydroxides (no significant peak for PF e or Feox ) reflects anoxic water condition. Absence of
Fepy at the sediment surface implies that syngenetic pyrite did not form, The Fepy content showed downcore increase as the mostabundant Fe-bearing phase.
Transformation of Porg and PF e to Pauth is called ”sink-switching”. At sediment surface in an oxygenated ocean, ferric(oxy)hydroxides precipitate to trap phosphate diffusing from deeper-anoxic sediment, and the phosphate concentration in porewater becomes high enough to precipitate authigenic apatite, meaning effective sink-switching (Slomp et al., 1996).
We compared our results with the previous work focusing on early diagenesis under oxic water mass (Ruttenberg and Berner,
1993). Two differences were clearly observed; the abundant Porg with sharp downcore decrease just below the sediment surface, and the similar downcore decrease in Ptot . We suggest that the amount of ferric (oxy)hydroxides relative to that of Porg
(PF e /Porg ) is a key factor for the retention of phosphorus in the sediments. Further, we quantified the degree of sink-switching,which appears to be related to PF e /Porg ratio. These results suggest the importance of PF e /Porg for sink-switching as an usefulproxy to estimate the extent of benthic phosphorus regeneration.
Very low PF e /Porg ratio or absence of PF e and Feox at the sediment surface reflect anoxic water condition, and further, absenceof Fepy and very limited abundance of Fecarb indicate ferruginous condition. Anoxic conditions are also indicated by downcore
increase in the Fepy content, FeHR /Fetot ratios, and DOP (degree of pyritization; Fepy /(Fepy +FeHCl )) values.
This study provides useful clues for modeling geochemical cycles of phosphorus and iron in the sediments overlain by photic
zone anoxia, and for understanding how Fe- and P-related redox proxies recorded early diagenetic processes of the sediments.

Keywords: phosphorus, iron, early diagenesis, photic zone anoxia, anoxic water mass

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BAO01-07

Room:105

Time:May 28 14:15-14:45

Development of Astrobiology with Exoplanet Explorations
TAMURA, Motohide1∗
1

University of Tokyo

Recent exoplanet researches have advanced significantly. More than 5000 exoplanets including promising candidates havebeen reported. Large telescopes like the Subaru Telescope have enabled the direct imaging observations of Jovian planets.
As a result, it has been shown that various types of stars have various types of planets around them. In particular, the transit
observations by the NASA’s Kepler mission and the long-term radial-velocity monitoring from the ground have discovered manysuper-earths and Earth-size planets. However, those planets discovered by the Kepler mission are mostly to far to be followed-up;
the low-mass habitable planets around nearby stars have not yet explored well. In order to study the universality of life undervarious environments, we study (1) to construct dedicated facility for long-term planet searches around red dwarfs (M-dwarfs) and(2) to conduct a large-scale survey for Earth-mass habitable planets around red dwarfs using the newly developed spectrometer
IRD. Those habitable planets are the best targets for a study of life under non-Earth-like environs (around low-luminosity andwith high stellar activities) using the TMT 30 meter telescope (expected FL in 2022).
Keywords: exoplanet, infrared, habitable planet, red dwarf

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BAO01-08

Room:105

Time:May 28 14:45-15:00

Search for extrasolar Earth-like planes in the habitable zone using InfraRed Doppler andthe Subaru
OMIYA, Masashi1∗
1

National Astronomical Observatory of Japan

Planetary systems around low-mass stars are attractive targets to search for Earth-mass planets in the habitable zone because
Doppler signals caused by the planets are relatively large and the habitable zone of the low-mass stars is located at close-inorbits. For the advantages, we have a plan to conduct a planet search program of low-mass stars by the Doppler method using
a new InfraRed Doppler (IRD) instrument to search for Earth-like planets. IRD to be mounted on the Subaru telescope in 2015
is composed of a very stable near-infrared high dispersion echelle spectrograph and a laser-frequency comb as a wavelength
calibrator of the radial velocity measurements. The main goals of the program are to detect Earth-mass planets in the habitablezone and to understand statistical properties, formation and habitability of extrasolar Earth-mass planets around low-mass stars.
We performed a survey simulation of our planet search program using IRD and the Subaru telescope and estimate expected
numbers of detectable planets around low-mass stars based on the results of theoretical population synthesis. In this simulation,
we expect more than 50 planets including the more than 30 Earth-mass planets and 10 Earth-mass planets in the habitable zone
on a suitable survey plan. And we would detect some transiting planets in the habitable zone, which can characterize planetaryatmosphere and may discuss the habitability of the planets by making follow-up observations.

Keywords: Earth-mass planets, low-mass stars, habitable zone

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BAO01-09

Room:105

Time:May 28 15:00-15:15

Absorption efficiencies of light-harvesting complexes exposed to the photoenvironmentof extrasolar planets
KOMATSU, Yu1∗ ; UMEMURA, Masayuki1 ; SHOJI, Mitsuo1 ; MEGUMI, Kayanuma1 ; SHIGETA, Yasuteru1
1

University of Tsukuba

The detectable size of extrasolar planets, which are planets outside our solar system, is getting smaller. Recently, an Earth-size
planet has already been discovered in the habitable zone, the region where a planet can hold liquid water on the surface. By
obtaining spectra of exoplanets, a lot of information is derived. For instance, the surface type affects the spectral shape. If we
detect the signal of vegetation on exoplanets, it will be a direct evidence of trace of life.
However, trace of vegetation on exoplanets is uncertain when the primal star is different from the Sun. As the first step
before detecting trace of vegetation on the planets, it should be examined what kinds of photoenvironments are acceptable forphotosynthetic organisms on the earth. Significant processes of photosynthesis, light absorption and excitation energy transfer(EET) processes, occur in light-harvesting complexes (LHCs) that contain photosynthetic pigments. Particularly, we modeled
the two processes in the LHC in purple bacteria (LH2), which absorb longer radiation than that in plants, since planets around M
dwarfs or M stars (cooler than the Sun) will be the observational targets. We investigated how efficiently the LH2 system absorbs
light energies depending on stellar radiation using the quantum chemical calculations.
To begin with photosynthetic pigments, the absorption spectra are calculated to evaluate absorption efficiencies under sevenstellar radiation spectra at the top of atmosphere (TOA) of the planets. The pigments and LHC have three main absorption bands:
Soret, the Qx and the Qy in order of the wavelength. We found that, among the six major pigments, the efficiencies around higher
temperature stars, the F, G and K type stars, vary depending on whether Soret bands are placed blueward or redward of 4000 Å
break, which is a steep change due to the absorption by some metals in stars below 400 nm. Around the M stars, Soret bands do
not contribute the efficiency anymore. Alternatively, Qy bands affect the efficiencies crucially.
Moreover, the EET process in the aggregation system of LH2 is investigated. The EET velocity becomes double when two
pigments in the central antenna are exchanged to the pigments with low excitation energies (from 850 to 890 nm). We also foundthat the efficiencies using estimated spectrum of the 19 LH2 system are maximized offset from the solar effective temperature(5778 K). The Soret band still has a contribution to the efficiency because the band is just around 4000 Å break.
In order to estimate the efficiencies on planetary surfaces where the organisms inhabit, the planetary atmospheric effects are
considered using simple radiation transfer calculations. The contribution of Qy region is affected due to absorption bands bywater vapor. Atmospheric conditions, i.e. oxidizing earth-like or reducing, vary the efficiencies around M stars significantly thanthose around the Sun. This is particularly because of the spectral overlapping in the Qy region.
In order to examine conditions which would lead to effective light absorption around M stars, we evaluate the efficiencies withdifferent conformations of the pigments and the LH2 and the solvent. The wavelength of absorption shifts about 120 nm longer
in the 19 LH2 system whose central metals of the pigments are exchanged to Pd, compared to that without the metals.
In any conditions as considered the planetary atmospheres, Soret bands contribute the efficiencies due to being enough redward
of 4000 Å break. Therefore, in the history of the Earth, there is a possibility for the organisms to have evolved the Soret band toabsorb light energies effectively.

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BAO01-10

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Time:May 28 15:15-15:30

Verification of abiotic formation of bioorganic compounds by utilizing Low Earth orbital
environment
KOBAYASHI, Kensei1∗ ; KEBUKAWA, Yoko2 ; KANEKO, Takeo2 ; MITA, Hajime3 ; BESSHO, Yoshitaka4 ;NAKAGAWA, Kazumichi5 ; SHIBATA, Hiromi6 ; IMAI, Eiichi7 ; TAKAHASHI, Jun-ichi6 ;ISHIBASHI, Yukihiro8 ; OKUDAIRA, Kyoko9 ; YANO, Hajime10 ; HASHIMOTO, Hirofumi10 ;YOKOBORI, Shin-ichi11 ; YAMAGISHI, Akihiko12
1

Yokohama National University / Natl. Inst. Natural Sciences, 2 Yokohama National University, 3 Fukuoka Institute of Technology, 4 RIKEN SPring8, 5 Kobe University, 6 Osaka University, 7 Nagaoka University of Technology, 8 Kyushu University,
9
University of Aizu, 10 JAXA/ISAS, 11 Tokyo University of Pharmacy and Life Science, 12 Tokyou University of Pharmacy andLife Science / NINSIn prior to the generation of the first terrestrial life, formation of bioorganic compounds such as amino acids seems to havebeen essential. There were two possible organic sources for that: Endogenously formed organic compounds and extraterrestrial organic compounds delivered by small bodies. Previously organic compounds could be formed effectively from strongly
reducing atmospheres. In these days, however, it was suggested that the endogenous formation was limited since primitive Earthatmosphere would have been only mildly reducing: Conventional energies such as thundering was not effective for the synthesis.
On the other hand, laboratory simulations showed that cosmic ray was a possible energy source to form nitrogen-containing organics including amino acids from even only slightly reducing atmospheres. We proposed to expose mildly reducing gas mixture
to the environment of low Earth orbit to see chemical evolution toward origins of life could take place without adding artificial
energies. Gas mixtures, such as a mixture of methane (5%) and nitrogen (95%) will be sealed in mall gas cells with or without
MgF2 windows, and attached to the Ex-HAM facility equipped on the Exposed Facility of JEM, and exposed to cosmic rays
and/or solar UV for more than a year. It is expected the formation of amino acid precursors by the action of cosmic rays and theenhancement of the yield by solar UV. The other possible experiments by using Ex-HAM were also discussed.

Keywords: planetary atmospheres, cosmic rays, Titan, solar ultraviolet light, amino acids, international space station

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BAO01-11

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Time:May 28 15:30-16:00

Formation of nucleobases and amino acids by meteorite impacts on early EarthFURUKAWA, Yoshihiro1∗ ; NAKAZAWA, Hiromoto1 ; SEKINE, Toshimori3 ; KOBAYASHI, Takamichi2 ;KAKEGAWA, Takeshi11Department of Earth Science, Tohoku University, 2 NIMS, 3 Department of Earth and Planetary System Science, Hiroshima
University
Emergence of biologically important molecules on the prebiotic Earth was a critical step for the origins of life. Miller-Urey
type synthesis was once demonstrated the formation of these molecules, such as amino acids and nucleobases. However, reduced atmospheres replicated in those experiments are not realistic considering hot accretion of primitive Earth and hence, thisraised questions about how such biologically important molecules were formed. Impact-induced reaction is a potential process that provides these molecules on the early Earth. Formation of a few simple amino acids, amines, and carboxylic acids
has been demonstrated in experimental simulation of impacts [1-3]. In this presentation, we report the formation of biologically important organic molecules in experiments simulating reactions induced by extraterrestrial objects impacting on the earlyoceans. The products contained cytosine and uracil, which are nucleobases found in both DNA and RNA. Proteinogenic aminoacids, glycine, alanine, serine, aspartic acid, glutamic acid, valine, leucine, isoleucine, and proline, were also formed as well
as non-proteinogenic of β-alanine, sarcosine, α-amino-n-butyric acid, and β-aminoisobutyric acid. Furthermore, methylamine,
ethylamine, propylamine, and butylamine were found in products. These organic molecules were formed from impact-induced
reactions from iron, nickel, forsterite, water, and ammonium bicarbonate. The yields of produced organics were dependent on
the amounts of both metallic iron and ammonium bicarbonate in the starting materials. Estimates based on the experimental
results suggest that the formation rate of biologically relevant organics by impacts exceeded the rate supplied by carbonaceouschondrites and was comparable to the flux of interplanetary dust particles (IDPs), although the concentrations of such organics
in IDPs remains unclear. These results significantly expand the availability of building blocks of life on the prebiotic Earth.
[1] Furukawa, Y., T. Sekine, M. Oba, T. Kakegawa, and H. Nakazawa (2009), Biomolecule formation by oceanic impacts onearly Earth, Nat. Geosci., 2, 62?66. [2] Goldman, N., E. J. Reed, L. E. Fried, I. F. W. Kuo, and A. Maiti (2010), Synthesis ofglycine-containing complexes in impacts of comets on early Earth, Nat. Chem., 2, 949?954. [3] Martins, Z., M. C. Price, N.
Goldman, M. A. Sephton, and M. J. Burchell (2013), Shock synthesis of amino acids from impacting cometary and icy planet
surface analogues, Nat. Geosci., 6, 1045?1049.

Keywords: Origins of life, Astrobiology, Amino acid, Meteorite, Impact, Organic compounds

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BAO01-12

Room:105

Time:May 28 16:15-16:30

Collisional growth and the evolution of the internal structure of Archean organic hazeparticles
FURUKAWA, Hikaru1∗ ; OKUZUMI, Satoshi2
1

Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 2 Department of Earth andPlanetary Science, Graduate School of Science, Tokyo Institute of Technology
The faint young sun paradox has been discussed for almost four decades. While many theories have been suggested regarding
temperatures high enough for primitive life and the existence of liquid water despite the lower luminosity of the Sun during theArchean age, the effect of greenhouse gasses such as CH4 and NH3 has especially been paid close attention. In order to ascertain
how much contribution the greenhouse gasses made to the warming of the early Earth, a more detailed understanding of theproperties of the haze on the Archean Earth, such as its shielding and cooling effects, is essential.
The Archean haze is believed to have been similar to that on Titan. The haze is composed of fractal particles, i.e., fluffy
aggregates of monomers. Although monomers collide with each other as they fall and grow as large fractal aggregates, thisfractal structure had been ignored and a simplified compact aggregate model has been used in the literature. More recently, Wolf
and Toon (2010) conducted simulations considering the fractal structure of the aggregates, but they did not consider compressionof the particles accurately. Their assumption of compression is based on the experiment conducted by Onischuk (2003), whichis considered to be inappropriate to apply to the haze on the Archean Earth.
Our research is aimed at assessing the properties of organic haze on the Archean Earth based on particle dynamics. We
calculate collisional growth and compression of haze particles properly taking into account the physics of collisional and static
compression. The result reflects the internal structural change of particles as they fall through the atmosphere after they areformed at higher altitudes.
We find that neither static compression nor collisional compression occur, thus the particles fall with its fractal structure
maintained. Simulations based on this assumption show that the haze on the Archean Earth were optically thicker in the UV
than the results by Wolf and Toon (2010). Thus, the Archean haze may have had a stronger UV shielding effect than previously
expected. Also, the simulations showed that the difference in the internal structure of particles affects the haze mass distribution
at each altitude. In the Archean organic haze, the haze is optically thin around the altitude where it is formed, and optically thickhaze concentrates below the formation layer.
In conclusion, effective UV shielding by the haze likely protected organics from photolysis and may have helped keep theatmosphere from reducing, which are both favorable for primitive life. The difference in altitude between the haze formation
layer and the haze residence layer could be the key to sustainable production of haze on early Earth. Although there remain
further questions to affirm that CH4 or NH3 provided effective warming effect on the early Earth, our result, combined with theresult of Wolf and Toon (2010), supports the argument for greenhouse gasses as the key solution to the faint young sun paradox.

Keywords: the early Earth, haze, fractal particle, the faint young Sun paradox, the internal structure change, the Archean

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BAO01-13

Room:105

Time:May 28 16:30-16:45

Polypeptide formation from oligopeptides
MUNEGUMI, Toratane1∗
1Department of Science Education, Naruto University of Education

Many scenarios for abiotic polypeptide formation have been proposed for many years, while the research results have shownthat both the large peptides and the structure variety of those from amino acids are difficult. Deamidation of asparagine in aqueous
solutions and dehydration of aspartic acid in dry conditions give polyaspartic acid upon heating. However, many other aminoacids have some difficulties to occupy their residues in backbone structure of the polypeptides. The reason may be considered
the diketopiperazine formation, which is carried out from usual linear dipeptides by intramolecular cyclization. This research
focuses the polypeptide formation from the oligopeptides containing asparagine, which is an anomalous amino acid. Chemicallysynthesized dipeptides Gly-Asn, Ala-Asn were heated in the aqueous solution to afford polypeptides with the molecular weightof 3000 to 5000 Da. Asparagine can be produced in the simulative abiotic conditions. If oligopeptides containing asparagine
residues had been obtained in the primordial conditions, these oligopeptides would have yielded polypeptides.

Keywords: oligopeptides, polypeptides, asparagine, heating

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BAO01-14

Room:105

Time:May 28 16:45-17:15

A reinvestigation of ALH84001 magnetite using SQUID microscopy
BUZ, Jennifer1 ; KIRSCHVINK, Joseph1∗ ; KOBAYASHI, Atsuko2 ; THOMAS-KEPRTA, Kathie3 ;CLEMETT, Simon3
1

California Institute of Technology, Pasadena USA, 2 Earth/Life Science Institute, Tokyo Institute of Technology, Meguro, Japan,
ESCG at NASA/Johnson Space Center, Houston TX, USA, 4 Earth/Life Science Institute, Tokyo Institute of Technology, Meguro, Japan3

The ˜4 Ga Martian meteorite ALH84001 has fine grained magnetite crystals embedded in carbonate blebs along its fracturesurfaces (McKay, 1996). Some of these magnetites are strikingly similar (in grain size, morphology, and composition) to thosemade by magnetotactic bacteria on Earth (Thomas-Keprta et al. 2009). Great debate has raged concerning the origin of theputative biological magnetites. Until recently careful magnetic examination of the magnetite in the carbonate blebs was not possible due to a lack of instrument sensitivity. The ultra-high resolution scanning SQUID microscope (UHRSS) now allows us to
study the magnetization of individual carbonate blebs that have been extracted from the meteorite. We are also able to visualize
magnetization along fracture surfaces and within the bulk rock by scanning thin slices of the meteorite with the UHRSS.
Two leading hypotheses exist to explain the magnetites found within the carbonate blebs: high-temperature shock deformation leading to the decomposition of iron-bearing carbonate minerals to form magnetite (Treiman and Essene, 2011), and thesedimentary deposition of previously-formed, mature magnetite in an aqueous micro-environment as would be the case for abiogenic origin (Thomas-Keprta, 2009). A well-established paleomagnetic technique which can distinguish between these two
hypotheses is the Fuller test of natural remanent magnetization (NRM) (Fuller et al. 1988) which probes the efficiency of themagnetization. If the magnetites grew in a solid state process inside the carbonates (like is suggested by Treiman and Essene(2011) they would be unable to physically rotate as they become stably magnetized and would have a highly efficient magnetization. If the magnetites were detrital (as would be expected from a biological origin scenario) the magnetization would be threeorders of magnitude less efficient because the particles would be subject to Brownian motion as they are deposited. Additionally,
the susceptibility of Anhysteretic Remanent Magnetization (ARM susceptibility) can be measured for the carbonate blebs. The
ARM susceptibility measures the inverse of the effective r.m.s. field strength between magnetic particles (Cisowski 1981). We
expect high ARM susceptibility for magnetites formed in situ because they would be evenly spaced as they form and therefore
not highly interacting. However, magnetite particles falling through a water column will clump together as they fall (Kobayashi
et al. 2006) and will have a low ARM susceptibility.
In order to conduct these paleomagnetic tests on the magnetites found within the carbonates and avoid interaction from othermagnetic particles in the bulk rock, we extracted the carbonate blebs by carefully flaking them from the fracture surfaces using
a non-magnetic needle. We then glued these blebs to magnetically clean microscope slides. We scanned the microscope slides
with the UHRSS and were able to observe quantifiable magnetization from the individual blebs. The Fuller test of NRM requires
demagnetization of the sample followed by application of an isothermal remanent magnetization (IRM). We have begun demagnetization of the sample. Thus far we observe a clear single magnetic component from NRM to 8 mT followed by chaotic changes
in magnetic direction and approximately uniform strength (Figure 1). At this stage it is unclear whether multiple magnetization
components will be recovered, our demagnetization is ongoing. Separately, we have measured slices of the ALH84001 bulk
rock and observed heterogeneous magnetization, consistent with the work done by Weiss et al. (2000). We have also observed
clustering of dipoles within the bulk rock, especially along fracture surfaces. Clustering of dipoles may indicate that multiple
deposition or alteration events occurred or that portions of the meteorite have been fractured after emplacement/formation of the
carbonates.

Keywords: Martian Life, ALH84001, Rock Magnetism, Paleomagnetism, Biogenic Magnetite, Meteorites

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BAO01-14

Room:105

Time:May 28 16:45-17:15

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BAO01-15

Room:105

Time:May 28 17:15-17:30

Were Archean volcanic glasses habitats for microbial organisms?
KAKEGAWA, Takeshi1∗
1

Tohoku Univ., Graduate School of Science

Submicron-tube structures have been found in quenched glasses of pillow lavas from Barberton (ca.3.4 Ga) and Abitibi (ca.2.7
Ga) Greenstone belts. These tubes are interpreted as products of bio-alteration (Furnes et al., 2003). However, abiotic processes
could form the same structure, and some researchers are questioning biogenic origin of the tube structure (Grosch et al., 2014).
Further examination of Archean volcanic glasses is important to constrain habitats of early life.
Here I examined pillow lavas from 2.7 Ga Abitibi Greenstone Belt in Canada. Pillow lavas have clear reaction rims, whichwere quenched and altered glasses before metamorphism. Typical mineral assemblages in reaction rims are paragonite, chlorite,
actinolite, titanite, quartz, calcite, pyrite and epidote. Low metamorphic grade (lower greenschist facies) is suggested by thosemineral assemblage. Mineral chemistries suggest that alkaline solutions was responsible for formation of primary minerals,
implying alkaline 2.7 Ga ocean.
Titanite occurs in aggregates of fine crystals in chlorite matrix, and often accompanied by unclear tubes. Occurrence of titanite
aggregates is identical to bio-alteration features found in other Archean pillow lavas. However, the length and density of tubes
are much less compared to others. The examined samples in the present study were less metamorphosed compared to others(upper greenschist facies). Absence of clear tubes in less metamorphosed rocks suggest that tubes in Archean pillow lavas were
not products of bio-alteration, but products of metamorphism.

Keywords: Archean, pillow lava, microbes, Abitibi

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BAO01-16

Room:105

Time:May 28 17:30-17:45

Mesoarchean pO2 and pCO2 based on REE and oxygen isotope geochemistry of BIF
from Barberton, South Africa
YAMAGUCHI, Kosei E.1∗ ; YAHAGI, Tomotaka R.1 ; KIYOKAWA, Shoichi3
1

Toho University and NASA Astrobiology Institute, 2 Toho University, 3 Kyushu University

A popular mechanism for BIF (Banded Iron Formation) deposition is that Fe-oxides were precipitated in deep-water settingby oxidation of dissolved Fe2+ supplied from submarine hydrothermal activity, by dissolved oxygen supplied from oxygenic
photosynthesis in the surface ocean. When Fe-oxides precipitated, rare earth elements (REEs) were adsorbed on their surface.
REE compositions of seawater have been recognized to reflect redox state of seawater and the extent of input from hydrothermal
activity. In this study, we aimed to estimate Mesoarchean seawater chemistry and temperature based on REE signatures of 3.2
Ga old BIFs. These are directly related to p O2 and p CO2 in the Mesoarchean atmosphere.
Samples were collected from outcrops of the Mapepe Fm at the bottom of the Fig Tree Group and Msauli Member in the Onverwacht Group, both belonging to the Swaziland Supergroup. Powdered rock samples were analyzed for their major element,
REE, and oxygen isotope compositions. Samples with <0.5 wt.% Al2 O3 are considered to be pure chemical precipitates andthus used for further discussion.
Chondrite-normalized REE patterns of the Mapepe samples show positive Eu anomaly,∑elevated Y/Ho ratios, and LREE>HREE.
Furthermore, there exist positive correlations among the extent of positive Eu anomaly, Fe2 O3 contents, and Y/Ho ratios. The
maximum Y/Ho ratios are surprisingly comparable to those of the modern ocean. These characteristics suggest a coherent story
for BIF deposition; Fe2+ emanated from submarine hydrothermal activity was oxidized to Fe3+ , which, with enhanced particle
reactivity, absorbed dissolved REEs and Y in the 3.2 Ga ocean, producing elevated near-modern Y/Ho ratios. The Msauli samples are mostly enriched in Al2 O3 and have clastics-dominated REE patterns, suggesting deposition at shallower, more proximal
setting.
We also estimate temperature of seawater 3.2 Ga ago from which the BIF precipitated to be around 60-70 ℃, based on theiroxygen isotope compositions of silicate- and Fe-oxide phases and their binary mixing model. Although crustal heat flux at thattime was most likely higher than today, the p CO2 in the Mesoarchean atmosphere should have been high enough to warm up theseawater under faint young Sun. The p O2 in the Mesoarchean atmosphere should have been high enough to oxidize dissolved
Fe2+ supplied from submarine hydrothermal activity.

Keywords: Archean, BIF, REE, Oxygen isotope, South Africa

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BAO01-17

Room:105

Time:May 28 17:45-18:00

Birth place of life on Hadean Earth: Geyser model
MARUYAMA, Shigenori1∗ ; EBISUZAKI, Toshikazu2
1

Earth-Life Science Institute, Tokyo Insitute of Technology, 2 RIKEN

Including us human being, life cannot survive with water only. The presence of water itself does not mean the emergence oflife automatically. So what is life? Life is composed of three major big molecules, which is (1) carbon (sugar), big monster
molecules, (2) metabolism which is the key to get energy. It does not work without P +K which is given from only landmass(provider of nutrients), and (3) self-replication, based on base pair. These 3 molecules are enclosed by membrane. That is life.
So where such molecules for life body are made on Hadean Earth. The most possible place for this process is geyser which
locates below the ground. The reason why geyser is thought to be the most suitable site to synthesize building blocks for life
body is (1) the ceiling of geyser located below the ground enable gases to be concentrated, such as CO, NH3, CH4, HCN, PO43and so on. (2) Amino acid or peptide is possible to be synthesized as necessary material can be provided within cavity of geyser.
(3) Periodicity is maintained due to the nature of geyser. (4) Heat source is secured due to the presence of uranium ore deposit
which is the alternative heat source instead of solar energy.

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