To study the genetic influence of low-dose ionizing radiation at the chromosomal level, frozen human lymphoblastoid TK6 cells were exposed to a 10 cGy dose delivered by a carbon-ion (24.5 ± 2.0 keV/μm) beam. Mutation assays were performed within a few days or after about one month of preservation at -80°C following irradiation. The results showed an increase in mutation frequencies at the thymidine kinase (TK) gene locus of 1.6-fold (2.5 × 10^-6 to 3.9 × 10^-6) and 2.1-fold (2.5 × 10^-6 to 5.3 × 10^-6), respectively. The relative distributions of the observed mutation classes were not changed by the radiation exposure in either assay. Multilocus analysis using two TK locus markers and eleven microsatellite loci spanning chromosome 17 were used for the analysis of TK mutants exhibiting a loss of heterozygosity (LOH). An interesting characteristic was detected using this system; interstitial deletion patterns were observed in hemizygous LOH mutants, which were specific for radiation exposure, and considered to be the result of end-joining repair of carbon-ion-induced DNA double-strand breaks. The relative increase in TK mutation frequency of the irradiated cells after the longer preservation at -80°C is probably due to the lower cell-viability compared to the unirradiated level. These results clearly demonstrate that this type of analysis can be used for the detection of low-dose ionizing radiation effects in frozen cells.

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Developing oocytes arrest at the prophase of meiosis I, while the hormone progesterone restarts the process, leading to full maturation as fertile eggs. In this study we investigated the effects of hypergravity on this phase of maturation using oocytes of Xenopus. No differences were found between 2G and 5G treated groups and untreated controls regarding time to resumption of maturation, as judged by the appearance of a white spot in the animal hemisphere. However the white spot itself was larger and brighter in treated oocytes at time of appearance, and became even more pronounced as maturation proceeded. These findings suggest that although hypergravity does not affect the resumption of maturation, it might adversely affect the subsequent process and final results.

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As a countermeasure for bone loss experienced by astronauts during the microgravity of spaceflight, and by aging patients (e.g., osteoporosis), the designs of devices for the application of lateral loads to the knee joint are described. These "knee-loading joint supporters (KJS)" are intended to clamp onto the human knee and provide variable, intermittent pulses of mechanical load. Based on previous experimentation with mouse models, it is expected that these KJS devices will facilitate human bone strengthening.

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Mars On Earth® (MOE) is a demonstration/research project that will develop systems for maintaining 4 people in a sustainable (bioregenerative) life support system on Mars. The overall design will address not only the functional requirements for maintaining long term human habitation in a sustainable artificial environment, but the aesthetic need for beauty and nutritional/psychological importance of a diversity of foods which has been noticeably lacking in most space settlement designs. Key features selected for the Mars On Earth® life support system build on the experience of operating Biosphere 2 as a closed ecological system facility from 1991-1994, its smaller 400 cubic meter test module and Laboratory Biosphere, a cylindrical steel chamber with horizontal axis 3.68 meters long and 3.65 meters in diameter. Future Mars On Earth® agriculture/atmospheric research will include: determining optimal light levels for growth of a variety of crops, energy trade-offs for agriculture (e.g. light intensity vs. required area), optimal design of soil-based agriculture/horticulture systems, strategies for safe re-use of human waste products, and maintaining atmospheric balance between people, plants and soils.

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Chemical evolution process to synthesize biomolecules should take place prior to the origin of life. Simulation experiments for the chemical evolution revealed that biomolecules such as amino acids, components of nucleic acids could be formed abiogenetically. Living organisms require both an information carrier and a catalyst. The RNA world theory hypothesizes that RNA played the roles of an information carrier and a catalyst in an early stages of origins of life. Here, I describe some simulation reactions of chemical evolution, and plausible model reactions of the prebiotic synthesis of RNA using a catalyst such as metal ions and clay minerals. Model reactions showed that replication of short-chained RNAs took place non-enzymatically. Obstacles for the RNA world theory are also described briefly.

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Several aspects of early evolution of life has been studied in several different research fields including planetary science, earth physics, geology, chemical evolution, environmental microbiology and molecular evolution. In this review I have summarized the recent results of geology, environmental microbiology on deep-sea hydrothermal area, and our recent studies on the common ancestor of all the living organisms on the earth (Commonote). The possible scenario on the origin and early evolution of life is also discussed.

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Eukaryotic autotrophs, generally assembled as plants, are polyphyletic and they appear across at least five super groups of eukaryotes, which indicate that photosynthesis has been horizontally transferred between different lineages of eukaryotes. This situation is explained by secondary endosymbioses that should have occurred between heterotrophic eukaryotes and primary plants (red and green algae). Evolutionary process generating new algal lineage can be considered by comparison of dinoflagellates and Hatena, a flagellate we recently found, all of which are likely under intermediate stages of secondary endosymbioses. Evolution of protein transport machinery to send nuclear encoded proteins back into the plastids was also considered referring recent reports of molecular biology.

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