| Project/Area Number |
18570067
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Animal physiology/Animal behavior
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| Research Institution | Ochanomizu University |
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Principal Investigator |
MOGAMI Yoshihiro Ochanomizu University, Graduate School of Humanities and Sciences, Professor (30166318)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,970,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥270,000)
Fiscal Year 2007: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2006: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | physiological activity / unicellular organisms / Paramecium / gravity response / energy metabolism / cell proliferation / complexity / space biology / 宇宙科学 |
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| Research Abstract |
Paramecium has been known to increase proliferation under microgravity in space, and reduce it under hypergravity. This effect of gravity on the proliferation has been explained in combination with the gravity-dependent control of the motile activity of Paramecium. In this research we attempted to test the hypothesis for the gravity-dependent modulation of the proliferation in Paramecium, in which Paramecium would decrease the energy expenditure for motility under microgravity and increase it under hypergravity because of the characteristics of 'gravitaxis' and 'gravikinesis'. In order to assess the feasibility of this hypothesis, Paramecium was grown under simulated microgravity by using a rotation apparatus (clinostat) to randomize their orientation with respect to gravity. The result was not consistent with the microgravity experiment in space : Paramecium proliferated slower under clinorotation. This may suggest that Paramecium expends more energy under simulated microgravity (clinorotation). We need more detailed discussion about the model. In order to characterize the energy expenditure of Paramecium, we measured the oxygen consumption using a fluorescence oxygen sensor simultaneously with the swimming speed on the basis of the optical slice method. It was revealed that the large amount of the metabolic energy (about 3/4 of the total) is consumed only for propulsive activity. Hydrodynamic calculation of the power liberated to the environment by swimming Paramecium demonstrated the extremely low efficiency of the conversion of the metabolic power to propulsion. These characteristics of energy expenditure would be unique for microorganisms including Paramecium living in a mechanical environment where large dissipation is inevitable of the kinetic energy through the interaction with surrounding water. We also conducted to improve as well as miniaturize the devices aiming at the measurement under altered gravity.
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