| Project/Area Number |
12440236
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
動物生理・代謝
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SHIMOZAWA Tateo Hokkaido Univ. Res Inst Elctr Sci., Prof, 電子科学研究所, 教授 (10091464)
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| Co-Investigator(Kenkyū-buntansha) |
NISHINO Hiroshi Hokkaido Univ. Res Inst Elctr Sci., Inst, 電子科学研究所, 助手 (80332477)
BABA Yoshitika Univ Illinois at Chicago. Dep. Zool. PD, 電子科学研究所, 助手 (30238232)
MIZUNAMI Makoto Tohoku Univ. Grad Sch Life Sci,. Asso. Prof, 大学院・生命科学科, 助教授 (30174030)
AONUMA Hitoshi Hokkaido Univ. Res Inst Elctr Sci., Inst, 電子科学研究所, 助手 (20333643)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥14,700,000 (Direct Cost: ¥14,700,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2001: ¥6,400,000 (Direct Cost: ¥6,400,000)
Fiscal Year 2000: ¥6,900,000 (Direct Cost: ¥6,900,000)
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| Keywords | mechanoreceptor / energy threshold / energy transduction / Brownian motion / informational entropy / insect / cricket / 機械感覚細胞 / 運熱揺動 / エネルギー増幅機構 / 感覚情報 / 感覚器 / 情報機械 / 機械設計 / 機械感覚 / 感覚細胞 / 刺激受容 / 初期過程 / 熱揺動スペクトル |
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| Research Abstract |
Mechanoreception is a fundamental element of animal-environment interaction and it is essential for the understanding of animal evolution. Mechanoreception has mainly been considered by a rather simple and macroscopic scheme of ionic channels deformed by membrane tension. Enormous high-sensitivities of mechanoreceptors have been reported in the eardrums of human and lacewing as 0.1 Angstrom i.e. one-tenth of a hydrogen atom diameter. It is obviously erroneous, however, to express the sensitivity of mechanical detector by displacement. Sensory cell is a measurement tool that converts external energy to informational entropy. The sensitivity must be discussed in terms of energy. All sensory cells receive a certain amount of energy, because any measurement without energy cost results in the thermodynamic inconsistency of Maxwell's demon. Energy threshold of the wind sensory cells in cricket is measured as very small values about 4×10^<-21> [Joule]. These mechanoreceptors would give rise a response shaken by Brownian motion of a single molecule.
Pathway of conversion from mechanical energy to cellular response, particularly of its initial process is still beyond our comprehension. In order to reveal its cellular mechanisms, a direct measurement of membrane current in response to the extremely weak mechanical stimuli near Brownian motion is attempted.
The receptor current was measured through a voltage clamp electrode, which also gives displacement to hair shaft. Shaft of a 1000 m long hair is clipped at 100 m to have electrical conduction through the hollow of hair shaft. Amount of energy estimated for the electrical current in response to 10-100 nm displacement at 100 m clipped shaft showed an energy amplification of about 10^6 times when compared to the mechanical energy given as the stimulus. The result suggests that the open-close of ionic channels is not a direct initial process of energy transduction in the mechanoreceptor cell.
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