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In this research, we clarify the aerosol dynamics during thin film formation by using the Aerosol Deposition (AD) technique under the microgravity conditions. The aerosol deposition technique is useful for making thin film of ceramics materials. We are now trying this technique to make thin film of thermally unstable materials, such as clathrate compounds and/or amorphous materials. However, it is difficult to make homogeneously the aerosol of these materials in the terrestrial conditions, because in the terrestrial conditions the fine particles of these materials are settled down below the chamber during making its aerosol. Thus, in the microgravity conditions, we hope to make homogeneously aerosol for good quality of thin film by the aerosol deposition technique. For this purpose, we developed the system of AD technique under microgravity conditions during parabolic flight by airplane. Using the system, we succeeded to make thin films of (Pb (Ti, Zr) O3)(PZT(Lead Zirconate Titanate)) by the AD technique under microgravity conditions. From present results, we discussed about the relationship between aerosol flow and deposition conditions under microgravity conditions.

Two Gy of heavy ion particles activated ERK1/2 at 2-5 min and 4-6 h after irradiation. Treatment of cells with 30 G for 10 sec activated ERK1/2 at 2-5 min and 4-6 h after treatment. Treatment of cells with 3D clinostat for 20 sec activated ERK1/2 at 2-5 min and 1 h after treatment. All these ERK1/2 activations were attributed to EGF receptor activation/transactivation.

It is important for human life in space to study the effects of environmental factors during spaceflight on a number of physiological phenomena. In the ICE-first experiment (International Caenorhabditis elegans Experiment-1, Mission DELTA, April 2004), we found that (1) both pachytene-checkpoint apoptosis and physiological apoptosis in germ cells occurred normally under spaceflight conditions and (2) certain genes related to signaling pathway of G-protein coupled receptor protein and to locomotory behavior tended to decrease in the spaceflown C. elegans. (3) In the hypergravity condition, we determined that the most susceptible aspect in the life cycle of this organism is the oocyte meiotic division for exclusion of polar bodies and the anterior-posterior polarization shortly after fertilization. (4) We also found several genes specifically responding to environmental stresses such as radiation by transcriptome analyses of entire genome using DNA microarray in several mutants and RNA interference (RNAi) animals. Since these phenomena and the identified genes are highly conserved in mammalian systems, the model experiments using this organism are useful to study the effects of space environment on human life. We are now attempting to study the RNAi effect, signal transduction, adaptation and evolution responding to space environment in future space experiments using the nematode C. elegans., 本研究では、モデル生物の1つである線虫C.elegansを用いて、微小重力や宇宙放射線をはじめとする複合的な宇宙環境ストレスが生物に及ぼす影響について調べることを目的としている。(1)我々はこれまでに、国際宇宙線虫実験ICE-first(2004年4月フライト)に参画し、宇宙で成長した線虫においても地上の対照区と同様に、減数分裂チェックポイント制御下のアポトーシスならびに卵母細胞成熟に伴う発生制御下のアポトーシスがともに正常に行われること、(2)筋肉関連の幾つかの遺伝子群ならびにタンパク質が発現レベルで顕著に低下することを見出してきた。(3)また、過重力による影響は受精直後の卵核の減数第1・第2分裂に最も影響を及ぼすことを証明してきた。(4)さらに、様々な環境ストレス(放射線など)の生物影響について、各種突然変異体やRNA干渉法(RNA interference: RNAi)による特異的な遺伝子発現の抑制体とDNAマイクロアレイを用いることにより、ゲノムワイドな分子モニターができることを明らかにしてきた。これらの結果から、複合的な宇宙環境ストレスが個体レベルに及ぼす分子影響を解析する上で、モデル生物の線虫が大変有効であることが示唆された。今後は、第1に宇宙環境におけるRNA干渉機構(RNAi)の効果を検証し、RNAiによりDNA損傷のチェックポイント制御を抑制した場合における細胞内での諸変化について調べる。さらに、アクチンや細胞骨格の再構築を介し、重力感受にも関わる可能性が想定されるRho-guanine nucleotide exchange factor(RhoGEF)の一変異体であるunc-73と野生株N2との遺伝子およびタンパク質発現の変化を比較し、シグナル伝達を含めたタンパク質のリン酸化に対する宇宙環境の影響について明らかにしたい。また、宇宙環境下で長期間、連続的な世代交代を通して生じる適応と変異・進化の方向性について明らかにすることを次なる研究課題として位置づけている。, JAXA Research and Development Report, 宇宙航空研究開発機構研究開発報告

The origin of Vestibular Evoked Myogenic Potentials (VEMP) is considered to include the sacculus as a sense receptor of vertical linear acceleration. In this paper, we report the influences of VEMP amplitude and latency to changes in the acceleration of gravity during a parabolic aircraft flight experiment. The parabolic flight was performed between an altitude of 7,000 and 9,500 meters and the detailed time course was as follows: (1) horizontal flight (1 G), (2) rapid ascending at 45 deg pitch up causing 2 G for 20 sec, (3) free falling causing microgravity for 20 sec, (4) descending at 35 deg pitch down causing 1.5 G. VEMP was recorded for 60 sec from the start of flight condition two to the end of flight condition four, during which the stimulating intensity was 105 dBnHL, and the stimulating frequency, 5 Hz. Seven healthy adults (six males and one female) who had no history of vertigo, deafness, or ear disease were selected as subjects, and VEMP was recorded from the left sternocleidomastoid muscles when the left ears were stimulated. The VEMP amplitude during microgravity was significantly greater than that during excessive gravity. By contrast, there were no differences among the three conditions which regard to latent VEMP. Changes in the sensitivity of the peripheral vestibular organ, i.e., sacculus, and/or the neural pathway of VEMP might increase the amplitude of VEMP during the microgravity condition. Furthermore, parabolic flight would be appropriate stimulation for evaluating saccular function on brief changes in vertical acceleration.

In osteoclast activity during space flight, inconsistent results have been reported in an in vivo study while osteoblastic function is consistently reduced by space flight. Bone matrix is an important function in the response to physical stress. However, there is no suitable in vitro co-culture system of osteoblasts and osteoclasts including bone matrix. On the other hand, fish scale is a calcified tissue that contains osteoblasts, osteoclasts, and bone matrix, all of which are similar to those found in human bones. Recently, we developed a new in vitro model system using goldfish scale. This system can be used to simultaneously detect the activities of both scale osteoclasts and osteoblasts with tartrate-resistant acid phosphatase and alkaline phosphatase as the respective markers and precisely analyze the co-relationship between osteoblasts and osteoclasts. In our co-culture system, osteoblasts and osteoclasts reacted sensitively to several degrees of acceleration, ultrasound stimulation, and micro-gravity of 3D clinostat. Therefore, we strongly believe that our in vitro co-culture system is suitable model for the analysis of bone metabolism under micro-gravity, such as that experienced in space flight.