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Hydrogen-rich hydrothermal areas, such as those in the Indian Ocean, may have had an influence on early evolution of life on Earth and thus have attracted interest because they may be a proxy for ancient ecosystems. The Kairei and Edmond hydrothermal fields in the Indian Ocean are separated by 160 km, but exhibit distinct fluid chemistry: Kairei fluids are hydrogen-rich; Edmond fluids are hydrogen-poor. At this region, the Central Indian Ridge shows an intermediate spreading rate, 48 mm year )1 as full rate, where the hydrothemal fields occur. Kairei field vent fluids show persistently high concentrations of H 2 . The Kairei field seems to be unique among hydrogen-enriched hydrothermal regions: most similar hydrogen-rich hydrothermal activity occurs along slowly spreading ridge, <40 mm year )1 . The geological and tectonic aspects of the Kairei and Edmond hydrothermal fields were studied to try to elucidate geological constraints on hydrogen production. Visual observations of the seafloor near Kairei from a submersible revealed olivine-rich plutonic rocks with olivine gabbro-troctolite-dunite assemblages exposed within 15 km of the vent field, with serpentinized ultramafic mantle rocks on the Oceanic Core Complex (OCC). The OCC area might be a recharge zone of Kairei hydrothermal activity producing H 2 -rich vent fluids. The chaotic seafloor within 30 km of the Kairei field reflects a magma-starved condition persisting there for 1 Myr. Asymmetric geomagnetic and gravity anomalies near the Kairei field can be used to infer that patchy olivine-rich intrusions are scattered within mantle ultramafics, where infiltrated seawater reacts with magma and ultramafic rocks or olivine-rich rocks. The heterogeneous uppermost lithosphere containing shallow olivine-rich rock facies surrounding the Kairei field provides abundant H 2 into the vent fluid through serpentinization. The hydrogen-rich Kairei field is hosted by basalt, with mafic-ultramafic olivine-rich lithology; the ordinary, hydrogen-poor Edmond field is hosted by a normal basaltic lithology. The contrasting geochemical signatures of the two fields reported here can also be found in ancient rocks from a juvenile Earth. This suggests that lithology-controlled generation of hydrogen may have operated for a long time and be relevant to the origin of life on Earth.

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We examined Daphnia pulex in Japan to clarify if they were representative of indigenous populations or colonized recently. Phylogenetic analysis of mtDNA suggests that Japanese lineages of D. pulex are immigrants from North America, and are hybrids formed with Daphnia pulicaria prior to this immigration. Based on the mtDNA sequences, the D. pulex individuals aggregated into four distinct genetic groups (JPN 1‐4) comprising a total of 21 haplotypes. Surprisingly, microsatellite analysis with 12 loci revealed only a single multilocus genotype per genetic group, suggesting that D. pulex populations in Japan are comprised of asexual individuals, derived from only four clones. According to the reported mutation rate of mtDNA, JPN 1 and 2, now widely distributed across Japan, were estimated to have invaded between 680 yr and 3400 yr ago, while JPN 3 and 4 colonized much more recently. Results also indicated that the invasion of some clones could not be attributed to recent human activities and most likely occurred by rare natural events. Since the evolutional longevity of asexual clones is thought to be limited, genetic diversity of D. pulex in Japan has the possibility of decreasing in the near future without addition of novel gene flow.

Water sorbed in eight coals of different ranks was analyzed by differential scanning calorimetry (DSC) over a temperature range from 123 to 293 K. On the basis of its congelation characteristics, the water was classified into three types: free water that is identical with bulk water, bound water that freezes at a lower temperature than free water, and nonfreezable water that never freezes in the present temperature range. The contents of the free and bound waters were experimentally determined from their respective heats of congelation, and the nonfreezable water was then calculated by difference. The congelation of the freezable water was also observed using proton nuclear magnetic resonance ( 1 H NMR) as the conversion of the slowly decaying into Gaussian components at 213-273 K. The fraction of freezable water as determined by 1 H NMR was in good agreement with that by DSC. The nonfreezable water was also found to have some mobility and thus gave exponential decays even at 213 K.

Scientific drilling at a submarine mud volcano shows that geofluid migration stimulates methanogenesis in the deep biosphere.

Although Texture Profile Analysis (TPA) is useful for most solid foods, the misuse of TPA parameters for liquid foods has led to misunderstandings and confusion. Here, we warn of the risk of misuse of TPA parameters for liquid foods.