著者

永野 匡昭 高辻 俊宏 吉川 勲 遠藤 暁 高田 純 星 正治

出版者

日本宇宙生物科学会

雑誌

宇宙生物科学 = Biological sciences in space (ISSN:09149201)

巻号頁・発行日

vol.12, no.3, pp.192-193, 1998-11

被引用文献数

1

著者

中村 輝子

出版者

日本宇宙生物科学会

雑誌

宇宙生物科学 = Biological sciences in space (ISSN:09149201)

巻号頁・発行日

vol.17, no.2, pp.144-148, 2003-08-01

著者

平林 久

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.17, no.4, pp.324-340, 2003 (Released:2005-12-27)

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It is much easier to find extraterrestrial intelligence than to detect simple organisms living on other planets. However, it is hard to communicate with such intelligence without the mutual understanding of inter-stellar communication protocol. The radio SETI (The Search for Extra-Terrestrial Intelligence) was initiated with the pioneering work of F. Drake in 1960, one year after the historical SETI paper by Cocconi and Morrison(1959). This talk explains that SETI evolves with two bases of science; the understanding of our universe and the development of technology. Since SETI has had strong connection with radio astronomy from its early beginning, the impacts of radio astronomical findings and technological breakthrough can be seen in many aspects of the SETI history. Topics of this talk include the detection of microwave 3 K background radiation in the universe. Interstellar atomic and molecular lines found in radio-wave spectra provide the evidence of pre-biotic chemical evolution in such region. Radio telescope imaging and spectral technique are closely associated with methodology of SETI. Topics of the talk extend to new Allen Telescope Array and projected Square Kilometer Array. Recent optical SETI and the discoveries of extra solar planets are also explained. In the end, the recent understanding of our universe is briefly introduced in terms of matter, dark matter and dark energy. Even our understanding of the universe has been evolutionarily revolved and accumulated after 1960, we must recognize that our universe is still poorly understood and that astronomy and SETI are required to proceed hand in hand.

著者

井上 勲

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.19, no.4, pp.276-283, 2005 (Released:2006-09-06)

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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.

著者

中村 輝子 吉田 正人

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.14, no.3, pp.123-131, 2000 (Released:2006-02-01)

参考文献数

67

被引用文献数

6 5 6

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: In this review, we attempted to summarize the effect of gravity on growth of woody plants, broad leaved trees, on earth. It is well known that in tilted broad leaved trees, tension wood formed in the secondary xylem causes negative gravitropism. Gibberellin has been shown to induce tension wood in weeping branch, causing its upright growth. Recent study has shown that seedling of Japanese cherry tree grew on three dimensional clinostat, a device that simulates microgravity, grew at random angles, and that the formation of secondary xylem, as supporting tissue for upright growth, decreased. In the decreased xylem formation, the inhibition of the differentiation and development of fiber cell was clearly observed. These results suggest that in attitude control and morphogenesis of stem in woody plant, secondary xylem formation seriously relates to gravity on earth. In woody plant, the mechanism of gravity perception and the following signal transduction have not yet been elucidated, although the recent study reported the possibility that endodermal starch sheath cells and plant hormones may play some role in the mechanism. Space experiment is expected to study these problem.

著者

最上 善広 石井 淳子 馬場 昭次

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.9, no.1, pp.17-35, 1995 (Released:2006-02-01)

参考文献数

28

被引用文献数

4 3

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In order to get an insight into the cellular mechanisms for the integration of the effects of gravity,we investigated the gravitactic behaviour in Paramecium. There are two main categories for the model of the mechanism of gravitaxis; one is derived on the basis of the mechanistic properties of the cell (physical model) and the other of the physiological properties including cellular gravireception (physiological model). In this review article, we criticized the physical models and introduced a new physiological model. Physical models postulated so far can be divided into two; one explaining the negative gravitactic orientation of the cell in terms of the static torque generated by the structural properties of the cell (gravity-buoyancy model by Verworn, 1889 and drag-gravity model by Roberts, 1970), and the other explaining it in terms of the dynamic torque generated by the helical swimming of the cell (propulsion-gravity model by Winet and Jahn, 1974 and lifting-force model by Nowakowska and Grebecki, 1977). Among those we excluded the possibility of dynamic-torque models because of their incorrect the oretical assumptions. According to the passive orientation of Ni2+-immobilized cells, the physical effect of the static torque should be inevitable for the gravitactic orientation. Downward orientation of the immobilized cells in the course of floating up in the hyper-density medium demonstrated the gravitactic orientation is not resulted by the nonuniform distribution of cellular mass (gravity-buoyancy model) but by the for-aft asymmetry of the cell (drag-gravity model). A new model explaining the gravitactic behaviour is derived on the basis of the cellular gravity sensation through mechanoreceptor channels of the cell membrane. Paramecium is known to have depolarizing receptor channels in the anterior and hyperpolarizing receptors in the posterior of the cell. The uneven distribution of the receptor may lead to the bidirectional changes of the membrane potential by the selective deformation of the anterior and posterior cell membrane responding to the orientation of the cell in the gravity field; i.e. negative- and positive-going shift of the potential due to the upward and downward orientation, respectively. The orientation dependent changes in membrane potential with respect to gravity, in combination with the close coupling of the membrane potential and the ciliary locomotor activity, may allow the changes in swimming direction along with those in the helical nature of the swimming path; upward shift of axis of helix by decreasing the pitch angle due to hyperpolarization in the upward-orienting cell, and also the upward shift by increasing the pitch angle due to depolarization in the downward-orienting cell. Computer simulation of the model demonstrated that the cell can swim upward along the “super-helical” trajectory consisting of a small helix winding helically an axis parallel to the gravity vector, after which the model was named as “super-helix model”. Three-dimensional recording of the trajectories of the swimming cells demonstrated that about a quarter of the cell population drew super-helical trajectory under the unbounded, thermal convection-free conditions. In addition, quantitative analysis of the orientation rate of the swimming cell indicated that gravity-dependent orientation of the swimming trajectory could not be explained solely by the physical static torque but complementarily by the physiological mechanism as proposed in the super-helix model.

著者

山岸 明彦 矢野 創 奥平 恭子 小林 憲正 横堀 伸一 田端 誠 河合 秀幸

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.21, no.3, pp.67-75, 2007 (Released:2007-12-26)

参考文献数

21

被引用文献数

15 13 2

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TANPOPO, dandelion, is the name of a grass whose seeds with floss are spread by the wind. We propose the analyses of interplanetary migration of microbes, organic compounds and meteoroids on ISS-JEM. Ultra low density aerogel will be used to capture micrometeoroid and debris. Particles captured by aerogel will be used for several analyses after the initial inspection of the gel and tracks. Careful analysis of the tracks in the aerogel will provide the size and velocity dependence of debris flux. The particles will be analyzed for mineralogical, organic and microbiological characteristics. To test the survival of microbes in space environment, microbial cells will be exposed. Organic compounds are also exposed to evaluate the possible denaturation under the conditions. Aerogels are ready for production in Japan. Aerogels and trays are space proven. All the analytical techniques are ready.

著者

中村 輝子

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.17, no.2, pp.144-148, 2003 (Released:2006-01-31)

参考文献数

11

被引用文献数

1 1

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Using the weeping branch of Japanese flowering cherry tree and its woody stem of the seedling grown under simulated microgravity condition by three dimensional clinostat, it was elucidated that the morphogenesis of its secondary xylem supporting the plant itself to grow upward is seriously controlled by gravity on earth with a sedimentable amyloplast as its sensor. Space experiment of woody plant is expected to elucidate such problem.