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第29回宇宙環境利用シンポジウム (2015年1月24日-25日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県, Space Utilization Research (January 24-25, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 18名, 資料番号: SA6000035008, レポート番号: ISAS-SUR29-S03

第29回宇宙環境利用シンポジウム (2015年1月24日-25日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県, Space Utilization Research (January 24-25, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 12名, 資料番号: SA6000035017, レポート番号: ISAS-SUR29-S12

近年、多くの生物種のゲノム配列が明らかにされるにつれ、遺伝子発現後の生体内でのタンパク質の動態を明らかにするためのプロテオミクス解析が多く行われている。植物においてもステージ毎や、塩や乾燥などのストレスに対するタンパク質の発現解析がシロイヌナズナ、イネ、トウモロコシ、エンドウを用いて行われている。本研究では、植物の根の重力屈性に関わるタンパク質を解析するために、シロイヌナズナ根およびトウモロコシコルメラ細胞を用いてプロテオミクス解析を行った。その結果、シロイヌナズナ根において、pyruvate dehydrogenase E1 component βsubunit、fructose-bisphosphate aldolaseおよび20S proteasome β subunit E1の3分子種が、電力刺激の経過時間に伴って、一過性的に分子量変化を起こしていることが明らかになった。また、重力刺激を処理すると、シロイヌナズナおよびトウモロコシの両植物とも、リン酸化タンパク質の発現が著しく減少していることも明らかになり、植物の重力屈性機構において、同一タンパク質の分子量変化およびリン酸化タンパク質が、重要な意義を持つ可能性が示唆された。, Gravity direction and force exert a profound influence on plant growth. When vertically growing plants are placed in a horizontal orientation, the so-called gravitational stimulation acts on the plants, resulting in the upward and downward growth of the apical shoot and root tip, respectively. This phenomenon in plants is called gravitropism. Proteomics may be the most promising technique to identify the proteins that are induced, repressed, or post-transcriptionally modified during gravity response in plants. In this study, Arabidopsis root apices and Maize columella cells proteins induced and/or changed by gravitational stimulation were analyzed using a proteomic method. As a result, the beta subunit of the E1 component of pyruvate dehydrogenase, fructose bisphosphate aldolase, and 20S proteasome beta subunit E1 protein appeared in two different molecular weight types during gravitational stimulation in Arabidopsis. The transitory changes in molecular weight in these three identified proteins were important findings although their functions in the gravity response remain uncertain. In addition, the phospho-protein was found remarkably decreasing by the gravitational stimulation in Arabidopsis and Maize, so, it was suggested that the phospho-protein was importance in gravity response mechanisms., 資料番号: AA0049799005, レポート番号: JAXA-SP-05-037

Gravity exerts a profound influence on plant growth. Proteomics may be the most promising technique to identify the proteins that are induced, repressed, or post-transcriptionally modified during gravity response in plants. In this research, the proteins controlled by gravity condition were identified. First, total protein extracted from Arabidopsis seedlings grown in 1 G-stationary and clino-rotated condition for seven days was used. Then, gravity-regulated proteins expression was analyzed by two-dimensional gel electrophoresis (2-DE). Several proteins which appeared different expressions between stationary and clino-rotated conditions were identified by Matrix Assisted Laser Desorption Ionization - Time Of Flight Mass Spectrometry (MALDI-TOFMS) analysis and Peptide Mass Fingerprinting (PMF)., 資料番号: AA0048095071

When cucumber (Cucumis sativus L.) seeds germinate in a horizontal position, a protuberance called a peg forms on the lower side of the transition zone. It has been shown that the endogenous levels of IAA that induces peg formation are significantly lower in the upper side of the transition zone than that in the lower side. To understand the mechanism of decrease of auxin in the upper side of the transition zone in response to gravity, cucumber cDNAs similar to PIN auxin efflux carrier gene were isolated and tissue specificity of their mRNA accumulation was investigated. The results indicate that mRNAs of CsPIN1, CsPIN4 and CsPIN6 accumulate in the transition zone of 24-h-old cucumber seedlings that initiate peg formation. CsPIN1 mRNA abundantly accumulates in xylem and endodermis. CsPIN4 mRNA abundantly accumulates in xylem. CsPIN6 mRNA abundantly accumulates in phloem and pith, and also accumulates in endodermis and cortex. Further study of these CsPINs will reveal the auxin transport system regulating peg formation of cucumber., 資料番号: AA0048095068

Gravity exerts a profound influence on plant growth. In gravity response of plants, gravitropism and gravimorphogenesis are known well. In the study of gravity response in plants, gravity signal transduction and transmission and expression analysis of protein-level are poorly reported. Cucurbit seedlings have unique gravity response as gravimorphogenesis. Namely, cucurbit seedlings develop a peg on the transition zone between the hypocotyls and root. Seedlings grown in a horizontal position on the ground suppress the development of the peg (negatively-controlled) on the upper side of the transition zone in response to gravity. Gravity-regulated protein expression was analyzed by two-dimensional (2-D) gel electrophoresis. As a result, the expression of 26kDa/pI5.5 and 90kDa/pI8.5 protein spots was more abundant in the lower (peg-developed) side than the upper (peg-suppressed) side of the transition zone. On the other hand, the expression of 44kDa/pI7.5 protein was more reduced in the lower side than the upper side of the transition zone. Next, to isolate putative genes cording protein spots, Arabidopsis and other plants protein databases were referred. As a result, isolated were a novel auxin-inducible gene, CsIAA4 and CsIAA3 as a transcript of 26kDa/pI5.5 protein and cell wall and glyoxylate cycle related genes, Csxylosidase and Csisocitrate lyase (CsICL), respectively, as a transcript of 90kDa/pI8.5 protein. The accumulation of CsIAA4, CsIAA3, Csxylosidase and CsICL mRNAs was more abundant in the lower side than the upper side of the transition zone. Furthermore, these genes expression of tissue specificity and gravity dependability was analyzed using 3-D clinostat. Especially, it was found that CsICL gene expression was tissue specific and only existed in the transition zone. Furthermore, the accumulation of CsIAA4, Csxylosidase and CsICL mRNAs was suppressed by clinorotation, but the accumulation of CsIAA3 mRNA increased by clinorotation. These data suggest that auxin, cell wall and glyoxylate cycle related genes were bearing the important and complicated role in gravity response of cucumber plants., 資料番号: AA0046917036

ウリ科植物の重力依存形態形成機構解明のためキュウリ苗条でのペグ(胚軸の鉤形突起)形成に対する微小重力の影響を調べた。宇宙飛行実験によって、ペグ形成、胚軸かぎ、および成長方向が重力によって支配されることを実証した。宇宙では胚軸と根茎との遷移部の両側にペグが発生し、地上ではペグ形成は重力によって負の制御を受けることを示している(Takahashiら、2000)。オーキシンに制御される遺伝子CS-IAA1はペグ形成の起こるゾーンで強く発現した(Fujiiら、2000)。地上実験で水平方向に成長させた苗では、CS-IAA1の転写は遷移部下側に非常に多かったが、宇宙実験で成長させたキュウリでは発現の差はなかった(Kamadaら、2000)。これらの結果は、ペグ形成における重力の影響は、オーキシンの再分布に起因することを意味している。負の制御においては、水平成長させた苗の遷移部の上側におけるペグ形成はオーキシン濃度の減少によって抑制されるかもしれない。オーキシン濃度のしきい値理論によって、重力による形態形成の負の制御、という新しい概念を説明することが出来た(Kamadaら、2000)。解剖学的な研究によれば、ペグとなるべき標的細胞があり、それは成長の初期段階で識別可能であることが示されている。超構造解析によれば、内部原形質の網状組織はペグとなるべき細胞中で良く発達すると考えられる。さらに、ペグ形成のためには標的細胞内での小胞体の発達と皮層微小管の配列変化が必要であることが分かった。また、キュウリの苗を用いる宇宙実験では、微小重力下で根茎は重力屈性応答の干渉なしに正の屈水性をしめした(Takahashiら、1999b)。したがって、この宇宙実験から、地上実験の結果と総合して、キュウリ苗条は重力依存形態形成、屈水性およびそれらの相互作用研究の理想的材料であることを示した。ペグ形成はウリ科植物に特有の現象であるが、これは、細胞成長の極性に対する重力感知機構、オーキシンの輸送と再分布、および細胞骨格の改変を含むものである。この系は植物生物学の重要課題を研究するための有用なモデルになり得る。, The effect of microgravity on the peg formation of cucumber seedlings was examined for clarifying the mechanism of gravimorphogenesis in cucurbitaceous plants. The space flight experiments verified that gravity controls the formation of peg, hypocotyl hook and growth orientation of cucumber seedlings. Space grown cucumber developed a peg on each side of the transition zone of the hypocotyl and root, indicating that on the ground peg formation is regulated negatively by gravity (Takahashi et al. 2000). It was found that the auxin-regulated gene, CS-IAA1, was strongly expressed in the transition zone where peg develops (Fujii et al. 2000). In the seedlings grown horizontally on the ground, CS-IAA1 transcripts were much abundant on the lower side of the transition zone, but no such differential expression of CS-IAA1 was observed in the space-grown cucumber (Kamada et al. 2000). These results imply that gravity plays a role in peg formation through auxin redistribution. By the negative control, peg formation on the upper side of the transition zone in the horizontally growing seedlings might be suppressed due to a reduction in auxin concentration. The threshold theory of auxin concentration accounted for the new concept, negative control of morphogenesis by gravity (Kamada et al. 2000). Anatomical studies have shown that there exists the target cells destined to be a peg and distinguishable at the early stage of the growth. Ultra-structural analysis suggested that endoplasmic reticulum develops well in the cells of the future peg. Furthermore, it was found that reorganization of cortical microtubules is required for the change in cell growth polarity in the process of peg formation. The space flight experiment with cucumber seedlings also suggested that in microgravity positive hydrotropic response of roots occurred without interference by gravitropic response (Takahashi et al. 1999b). Thus, this space flight experiment together with the ground-based studies has shown that cucumber seedling is an ideal for the study of gravimorphogenesis, hydrotropism and their interaction. Although peg formation is seen specifically in cucurbitaceous seedlings, it involves graviperception, auxin transport and redistribution and cytoskeletal modification for controlling cell growth polarity. This system could be a useful model for studying important current issues in plant biology., 資料番号: AA0003840003, レポート番号: NASDA-TMR-000004E

An agravitropic mutant of morning glory (Pharbitis nil.), weeping, has defect in shoot gravitropism. The previous results showed that weeping also showed defect in proper endodermis development and in shoot circumnutation, and such defect in circumnutation was also observed in similar endodermis-less Arabidopsis mutant, scarecrow (scr). In search of the mutated gene of weeping, cDNAs for SCR homolog from morning glory (PnSCR) were cloned from both wild type and weeping, respectively, and analyzed. An amino acid insertion was found in PnSCR from weeping. To investigate whether this insertion inactivates the PnSCR functions, complementation test was performed by introducing wild and weeping type PnSCR to the different Arabidopsis scr mutants respectively. As a result, endodermis-less and shoot agravitropic phenotypes were rescued by wild type introducing PnSCR, whereas introduction of weeping type PnSCR did not rescue them. Moreover, shoot circumnutation was also restored in scr mutant to which wild type PnSCR was transformed, but transformed weeping type PnSCR did not restore shoot circumnutation. These results strongly suggest that defects in gravitropism, proper endodermis development, and circumnutation observed in weeping are attributable to the loss of function of PnSCR. Possibility for usage of weeping morning glory as a new model plant in space biology is discussed., 資料番号: AA0048095069

Plants determine the directional growth by responding to various environmental stimuli such as gravity, moisture, light and touch. Plant movements due to tropisms, nutation and other morphism represent those responses that interact from one another. However, plants must somehow integrate such various responses to environmental cues for exerting a proper response leading to an appropriate directional growth under specific stressful conditions. It has been shown that gravitropism strongly interacts with hydrotropism in seedling roots and suggested that the mechanisms for controlling auxin transport and distribution play essential roles in those responses. To understand molecular mechanisms of auxin dynamics to be destined by different environmental stimuli, genes of putative auxin carriers, CS-PIN1 and CS-AUX1, were isolated from cucumber and their expression patterns at both transcriptional and post-transcriptional levels were examined. The results suggested that a balance of the activity and/or localization of the two types of carriers (influx and efflux carriers) played an important role in controlling the localized concentration of auxin in gravistimulated tissues of cucumber seedlings. Because auxin dynamics also plays an essential part in hydrotropism, the expression patterns of CS-PIN1 and CS-AUX1 in hydtrostimulated roots of cucumber are now analyzed and it is compared with that in gravistimulated ones. In addition, this approach will be extended to gravitropism, hydrotropism, waving response and phototropism in Arabidopsis roots because unique mutants has been recently discovered that show specific interactions among those responses. A system of spaceflight experiment will be established for the study of auxin dynamics in microgravity, which reveals mechanisms underlying the integration of different stimulus-sensing systems by roots for controlling their directional growth., 資料番号: AA0045438031

第26回宇宙利用シンポジウム(2010年1月25日-26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan), A fundamental study was conducted to develop the experimental system to investigate effects of space environment on vegetative and reproductive growth of plants in their life cycles. Sap flow in plant stems plays an important role to transport fluid and nutrients internally from roots to leaves. In this study, the sap flow in tomato stems was assessed using a heat flow method at 0.01 and 1.0 g for 20 seconds each during parabolic airplane flights in order to clarify the effect of microgravity on the sap flow in stems. Heat generated with a small heater installed in the stem was transferred upstream and downstream by conduction and upstream by convection with the sap flow through xylems of the vascular tissue. Thermal images of stem surfaces near heated points were captured using infrared thermography and the internal heat convection corresponding to the sap flow was analyzed. In results, the sap flow in stems at 0.01 g was suppressed under a retarded air condition at a wind speed of 0.1 m/s compared with that at 1 g. No suppression of the sap flow was observed under a stirred air condition at a wind speed of 0.5 m/s. Suppressed sap flow in stems would be caused by suppression of transpiration in leaves and would cause restriction of water and nutrient uptake in roots. The forced air movement is essential to grow healthy plants under microgravity condition in space., 形態: カラー図版あり, 共催: 日本学術会議, 著者人数: 16人, Physical characteristics: Original contains color illustrations, joint hosting: The Science Council of Japan, 資料番号: AA0064730062

第26回宇宙利用シンポジウム(2010年1月25日-26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan), Plant roots display not only gravitropism but also hydrotropism for determining their growth orientation. Previously, we found that gravitropism interferes with hydrotropism, which led us to prepare a spaceflight experiment for separating hydrotropism from gravitropism under microgravity condition, namely in KIBO module of International Space Station. Cucumber seeds are embedded in the water-absorbable plastic foam before launch. The cultivation chamber has two ports; one is for supplying water to this foam and the other is for supplying water or NaCl solution to a filter paper situated at the opposite side of the foam. Onboard, crew will connect plastic syringe and the port by tubing and supply water or NaCl solution for allowing seed germination and for controlling moisture gradient. Considering microgravity conditions, we were concerned about feasibility of these water- and salt-solution-delivery systems. We therefore conducted parabolic-flight-experiments to test these systems under altered gravity conditions. Under microgravity conditions, we injected 9.5 mL of water to the foam by using this system, and its absorption pattern was recorded by video camera and compared it with the result on the ground. The results showed that on the ground the injected solution tended to accumulate on the bottom flank of the foam and took longer than 90 seconds to be fully distributed into the foam. Under microgravity conditions, on the contrary, the solution rapidly distributed, and it took just 15 seconds to complete injection. These results allow us to properly calculate crew time required for onboard operation and to validate the systems to supply solutions into the chamber in space., 共催: 日本学術会議, joint hosting: The Science Council of Japan, 資料番号: AA0064730066

第26回宇宙利用シンポジウム(2010年1月25日-26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan), The space environment, such as microgravity and space radiation, is a kind of stress for the living organisms which influence from a cell to an individual organism level, and the stress biology in space research working group has been examining concretely the basic biological research subjects of space environment stress responses on living organisms. In this year, we have participated in a sample-share research program of the ASI-MDS (Mice Drawer System) mission using mice through science reviews by ASI (Agenzia Spaziale Italiana)., 形態: カラー図版あり, 共催: 日本学術会議, 著者人数: 26人, Physical characteristics: Original contains color illustrations, joint hosting: The Science Council of Japan, 資料番号: AA0064730075

第26回宇宙利用シンポジウム(2010年1月25日-26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan), When cucumber seeds are placed in a horizontal position for germination, resulting seedlings develop a specialized protuberance, termed the peg, on the lower side of the transition zone between the hypocotyl and the root, due to gravistimulation. On the other hand, in our spaceflight experiment of STS-95, cucumber seedlings grown under microgravity conditions developed a peg on each side of the transition zone, suggesting that gravistimulation was required for suppressing the peg formation on the upper side of the transition zone. We considered this as negative regulation of morphogenesis (peg formation) by gravity. We have shown that exogenous auxin induces peg formation and that indole-3-acetic acid (IAA) content in the upper side of the gravistimulated transition zone is less than that in the lower side. Furthermore, inhibition of auxin efflux by TIBA treatment induces the peg formation on the upper side of the transition zone in addition to the lower side. Therefore, we proposed that gravistimulation activates auxin efflux, decreases auxin level and suppresses peg formation on the upper side of the transition zone. To examine this hypothesis, we first investigated the localization pattern of auxin efflux carrier CsPIN1 proteins in endodermal cells that are thought to sense gravity. The results suggested that its localization pattern changed to transport auxin to the lower side of the transition zone 30 min after gravistimulation. We then analyzed IAA contents in the transition zone after gravistimulation using GC-SIM-MS. Results of our quantification of IAA contents indicated that asymmetric IAA distribution was induced 30 min after gravistimulation. These results suggested that auxin efflux carrier CsPIN1 proteins in endodermal cells would induce asymmetric auxin distribution in the transition zone and play an important role in negative regulation of peg formation by gravity., 共催: 日本学術会議, 著者人数: 11人, joint hosting: The Science Council of Japan, 資料番号: AA0064730065

第26回宇宙利用シンポジウム(2010年1月25日-26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan), Plant life cycle consists of successive phases of vegetative and reproductive growth. The effects of altered gravity conditions on reproductive growth are not understood well compared to vegetative growth. We have performed proteome analysis to examine the effect of hypergravity on reproductive growth of Arabidopsis (Arabidopsis thaliana (L.) Heynh. ecotype Columbia-0). Plants grown for 20-26 days under were exposed to hypergravity at 300 x g or placed at 1 x g for 24 h in the dark. Proteins extracted from the flower buds with a buffer containing Triton X-100 were subjected to two-dimensional electrophoresis. The polypeptides, that were up-regulated or down-regulated by hypergravity, were analyzed by matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry, to compare the present proteome results with our previous transcriptome results. Proteome analysis showed that hypergravity changed the expression of proteins involved in protein folding and translocation, ethylene synthesis and stress response., 共催: 日本学術会議, 著者人数: 29人, joint hosting: The Science Council of Japan, 資料番号: AA0064730067

第26回宇宙利用シンポジウム(2010年1月25日-26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan), Studies of our working group are aimed at understanding the graviperception mechanism and its interactions with mechanisms of other gravity-influenced phenomena of plant growth and development. Our collaborative works will bring about hypotheses on the molecular mechanisms underlying plant responses to gravity, which will be further verified by spaceflight experiments. This approach will also lead to the establishment of technology useful for controlling plant growth and development in space. We have continued our studies to reveal mechanisms underlying graviperception and its signal transduction in plants by using gravitropic mutants, and found various genes and molecules responsible for the mutations. Also, we have studied the gravity-influenced growth and development of plants; namely, gravimorphogenesis of cucumber seedlings, shoot circumnutation, and hydrotropism in seedling roots. The results obtained suggested molecular cascades for graviresponse and molecular networks for the interactions among the gravity-influenced phenomena. Based on these accomplishments, we are attempting to establish models and hypotheses to be verified by spaceflight experiments. Some of the subjects being dealt in this project are to be flown in this year. Currently, we are preparing to propose another spaceflight experiment on circumnutation and its relationship to graviresponse in plants., 共催: 日本学術会議, 著者人数: 17人, joint hosting: The Science Council of Japan, 資料番号: AA0064730068

第25回宇宙利用シンポジウム(2009年1月14日-15日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan), When root are exposed a moisture gradient, roots sense the gradient and bend toward the higher water potential or moisture, which is so called root hydrotropism. Because root system is responsible for water acquisition, root hydrotropism is considered to be important for drought avoidance. Although the difficulty of separating hydrotropism from gravitropism on Earth prevented us from analyzing the genuine hydrotropism, our previous results suggested that root gravitropism interferes hydrotropism and that auxin plays an important role in both tropisms. Furthermore, in cucumber, both hydrotropism and gravitropism are found to be accompanied with asymmetric expressions of auxin-inducible genes. To reveal the role of auxin in root hydrotorpism, it is necessary to use microgravity condition for differentiating hydrotropism from gravitropism. We proposed to use the microgravity environment to separate hydrotropism from gravitropism and dissect respective mechanisms in cucumber roots, which has been approved as a forthcoming spaceflight experiment by International Space Life Science Working Group in 2004. In this presentation, our recent ground-based experiments for demonstration of cucumber root hydrotropism in space are described., 資料番号: AA0064297009

第25回宇宙利用シンポジウム(2009年1月14日-15日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan), A fundamental study was conducted to develop the experimental system to investigate effects of space environment on vegetative and reproductive growth of plants in their life cycles. In this study, the transpiration rate of plant leaves were evaluated at 0.01, 1.0 and 2.0 g for 20 sec each during parabolic airplane flights in order to clarify effects of microgravity on the water vapor exchange between plants and the ambient air. The transpiration rate of leaves was suppressed by increasing the water vapor transfer resistance due to restricted free air convection under microgravity conditions. Planning for evaluating performance of the water recycle system in a plant growth chamber under microgravity conditions is also described., 形態: カラー図版あり, 資料番号: AA0064297011

第25回宇宙利用シンポジウム(2009年1月14日-15日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan), In order to assess the effect of gravity on life cycle in the Arabidopsis plant, we have organized a working group, consisting of 29 members from different research fields of plant science. The goal of our working group is to clarify whether or not the seed to seed life cycle of a higher plant, Arabidopsis thaliana L., is normally completed under microgravity condition in the International Space Station, using plant experiment units embarked in JAXA's cell biology experiment facility with a centrifuge to produce 1 g condition. In this year, we examine the effect of hypergravity (300 x g) on proteome in floral buds. Proteins were extracted from floral buds excised from plants grown at 300 x g or 1 x g for 24 hr, and then subjected to two dimensional electrophoresis. It was turned out that hypergravity increased the expression of 9 protein spots, and decreased that of 5 spots. These protein spots were analyzed by matrix-assisted laser desorption ionization time flight mass spectrometry. Proteomics results were compared with our previous transcriptome data., 資料番号: AA0064297012

第22回宇宙利用シンポジウム(2006年1月17日-19日, 日本学術会議6階会議室 六本木、東京), The Twenty-second Space Utilization Symposium (January 17-19, 2006: Science Council of Japan, Roppongi, Tokyo, Japan), In order to develop the experimental system for carrying out experiments with plants in space successfully, a working group was organized. The main objective is to clarify the effects of space environment on vegetative growth and reproductive growth of plants in their life cycles., 共催: 日本学術会議, 著者人数: 15人, Meeting sponsors: The Science Council of Japan, The Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS)(JAXA), 資料番号: AA0064113101

第22回宇宙利用シンポジウム(2006年1月17日-19日, 日本学術会議6階会議室 六本木、東京), The Twenty-second Space Utilization Symposium (January 17-19, 2006: Science Council of Japan, Roppongi, Tokyo, Japan), Terrestrial plants control their orientation of growth for obtaining water and nutrients, harvesting light for photosynthesis, and anchoring themselves. This is the feature fundamentally important for plants to survive under various environmental conditions and to achieve efficient production of carbohydrates as primary energy of all organisms. To accomplish this task, plants respond to gravity for controlling their growth and development under terrestrial environment. For example, roots and stems display gravitropism. In addition, graviresponse has been implicated to be involved with circumnutation in plants. Another example of gravimorphogenesis is seen in the seedlings of cucurbitaceous plants; namely, unilateral positioning of a peg on the transition zone between the root and the hypocotyl. Plants also respond to various environmental cues, which interacts with graviresponse. However, mechanisms underlying the graviresponse and its relationship to other growth and development are not fully understood. Members of our working group have attempted to reveal the molecular mechanisms that essentially function in graviperception system and its involvement in various aspects of plant growth and development. We will further develop our research on the molecular dissections for obtaining general principles underlying the graviperception and its role in plant growth and development. Then, we will establish a model for spaceflight experiments to verify the hypothesis., 共催: 日本学術会議, 著者人数: 16人, Meeting sponsors: The Science Council of Japan, The Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS)(JAXA), 資料番号: AA0064113095

本研究は、旧宇宙開発事業団宇宙環境利用研究システムで実施されていた先導的研究、「力学刺激の細胞内生体信号への変換過程の研究」、「血管内皮細胞等を利用した重力感受・応答機構の解明」、「植物の重力応答研究」を、2003年10月の独立行政法人宇宙航空研究開発機構の発足に伴い、宇宙科学研究本部ISS科学プロジェクト室のISS/JEM利用科学プロジェクト研究として、「重力感受応答に関わる細胞内外への分子実体および重力刺激の生体内信号への変換と伝達過程の解明」という表題のもと、実施した。本研究では、生体における個体、組織、細胞レベルでの重力感受と応答機構の解明を目標として、特に、重力感受分子実体の同定、細胞骨格系と重力感受機構との関連性、重力刺激情報の伝達機構の分子的解明を目指した。本稿の構成を以下に示す。(1)骨芽細胞を用いた力学刺激の細胞内生体信号への変換過程の研究(2)培養細胞の重力ベクトル変化環境下における細胞骨格系への影響(3)植物の重力応答に機能する分子のプロテオミクス研究。第1章では、宇宙滞在による骨量減少のメカニズム、特に骨形成や骨吸収の現場で機能する個々の細胞が、重力環境情報を取得し応答する機構について、分子レベルでの研究を進めた。第2章では、機械的刺激の受容応答機構に関する研究が進んでいる血管内皮細胞を用い、細胞レベルでの重力感受応答機構について微小管やアクチンファイバーなどの細胞骨格系とその形成にかかわる低分子量Gタンパク質を中心に解析した。第3章では、植物における重力応答反応において、重力の変化によって発現が変化するタンパク質を網羅的に解析した。各テーマはそれぞれ異なる切り口から重力感受応答メカニズムの解明を進めているが、細胞骨格系と生体内信号伝達における重力影響や力学刺激の細胞内外の情報伝達系との関連、プロテオミクス解析による細胞骨格やホルモン制御タンパク質の発現変化などが明らかされ、種の違いを超えた、生物に共通な生体物質にそれぞれ焦点が絞られてきており、重力刺激情報の生体内信号への変換とその情報伝達の分子実体と伝達経路の解明に向けて大きく前進した。, In previous space flight experiments, the effects of microgravity on living organism were observed. The molecular mechanisms of microgravity effect, however, have not been cleared. In order to elucidate the detail of the gravity sense and response mechanisms on life, focused were the three topics as follows: 1) the transferring mechanisms of mechano-stress into innercellular signal in osteoblast cells, 2) cytoskeleton and small G proteins involved in gravity sense and response in endothelial cells, 3) proteomic approaches of gravitropic-related molecules in higher plants. In each topic, it could be found that the common signal pathways functioned as gravity response in various species. The studies could be advanced greatly on how gravity signals were transferred into biochemical reactions and what molecules are important on the transferring process., 資料番号: AA0048705000, レポート番号: JAXA-RR-04-049