Japanese tree frogs (Hyla japonica ) were sent to the MIR station and spent eight days in orbit in December, 1990. On the MIR, floating frogs stretched four legs out, bent their bodies backward and expanded their abdomens. Some frogs showed tumbling. On a surface of something, more than half of frogs bent their neck backward, pressed their abdomens against the substrate with relaxation of their hindlimbs, and walked backward. This behavior was observed on parabolic flights and resembles the retching behavior of sick frogs on ground. The frequency of failure to land after a jump decreased in the later observation period. This result suggests that frogs could adapt to microgravity. Behaviors ofthe flight frogs became normal as early as 2.5 hours after landing.

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Microgravity effects on human factor were observed through a series of manual control experiments conducted in the First Material Processing Test. The Japanese Payload Specialist, who operated a stick to control a double integral controlled element against pseudo-random disturbance, felt pain in fast eye movement during orbital experiments. He was obliged to fix his line of sight at the center of display and to watch the displayed error movement using peripheral view. He also felt difficulty in supporting his body against reaction force of his hand movement. During two or three days after landing, disturbance was observed in the PS's posture. The operator's input and output data wiIl be analyzed by the cross spectral analysis to obtain the operator describing function and the remnants. Such data wiII be utilized in space man-machine system design. EIectro-myogram of hand and electro-oculogram data will also be analyzed.

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A variety of animal behavior under microgravity has been found in the experiments using parabolic aircraft flights and in space. Forward looping in fish and tadpoles is contrast to backward looping of pigeons, while frogs and hamsters extend their extremities with the head turning backward. Postures of monkeys and man, on the other hand, are different from those of above animals. Loss of vestibular input must be common to all of these animals and there may be some similarities among the species in the sensory conflict against it. Advancing animals experiments in space, it is important to make further progress in comparative neurology particularly regarding the posture control and behavior of animals.

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Human clearly perceive and respond to microgravity as an individual unit and manifest such abnormalities as space sickness, and decrease in Calcium in the bones. It is not fully understand, however, whether each of the cells perceives and responds to microgravity. This is a problem of a major scope in gravitational and space biology. I discussed here methods of studying ceIIular response to microgravity cellular response in the space, and others. The cell culture can be applied to elucidate the mechanism of gravity response in cells. FMPT was conducted in the space shuttle Endeavor launched on September 12, 1992, and I and my colleagues had a study concerned the effects of microgravity on the ultrastructure and function of mammalian cells in culture. The study was conducted with the following three major objectives: The first objective was to study the change under microgravity in the cytoskeletons using Monkey's renal cells JTC-12. The second objective was to study energy consumption by cultured cells under microgravity and production of urokinase of the ceIIs. The third objective was to establish the basic techniques of cell culture in the space. Dr. Mouri, payload scientist, conducted the experiments during the flight as scheduled. Cells cultured in culture chambers ACCl and ACC2 were used for the objective 1 and phase contrast microscopic photographs taken in the space laboratory. After trypsinization, the cells were cultured again and fixed with glutaraldehyde after a prescribed period of time. Culture chambers ACC2 and ACC4 were for the objective 2 and 3 and the used cells were brought back to the earth alive. Analysis of photos taken by Dr. Mouri is in progress. Cultured cells were in good conditions under microgravity, and satisfactory results for establishing cell culture techniques, were obtained. Cultured human and animal cells have been used in more than 20 space experiments since Discoverer 17 Iaunched in 1960 and the cellular response to microgravity may differ depending on the cell types. It is possible to conduct experiments on earth using short term microgravity by a drop tower or simulated microgravity using clinostat. Hypergravity using a centrifuge is also useful for studying the cell response to gravity. Since opportunities for space laboratory experiments are Iimited, these equipments are believed to be most useful for sophistication of space experiments.

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In space environment, radiation dose due to high charge and high energy particles (HZE) and other cosmic radiation is, in general, 2 to 3 orders of magnitude greater than the dose from cosmic rays which are falling on the surface of the Earth. Although radiation dose during 7 to 8 day Shuttle mission is so small as to cause any harmful effect on astronauts, this will change with the advent of Space Station and manned Mars Mission. The purpose of our experiment is to examine possible effects of space radiation on living organisms, particularly the genetic effects. For this, we are analyzing mutations induced in fruit flies of the species Drosophila melanogaster during the space flight.

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