| Project/Area Number |
13640685
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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 |
動物生理・代謝
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
ICHIKAWA Toshio KYUSHU UNIVERSITY, Graduate School of Science, Associate Professor, 大学院・理学研究院, 助教授 (50136420)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Silkworm / neurosecretory cell / neuropeptide / insulin / firing activity / ultradian rhythm / circadian rhythm / coupling |
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| Research Abstract |
Four pairs of cerebral neurosecretory cells producing bombyxin (an insulin-like peptide) in the silkmoth Bombyx mori show rhythmic firing activity. Analyses of activity rhythms of individual cells and cross-correlation between cells revealed a large variability in ultradian firing rhythms and heterogeneity in cellular coupling. A total firing activity of a population of bombyxin producing cells showed a complex rhythmicity with multiple frequency components. Based on the total firing patters of cells and time course of bombyxin degradation in the haemolymph, temporal patters of bombyxin concentration in the haemolymph were estimated and power spectra were calculated. Power spectra showed a typical 1/f characteristics of fluctuation in a broad range of frequency, thereby suggesting that neurosecretory cells coupled weakly with each other to generate such a characteristic patter of hormone secretion, a temporal pattern which seems suitable for maintaining biological actions of the hormone. Brain-CC-CA complex was isolated and placed in a physiological saline and firing activity of bombyxin producing cells was examined. Similar rhythmic firing activity was observed in such an in vitro system and it was completely blocked by application of atropine in the saline bath, hence the activity of neurosecretory cells is regulated by cholinergic neurons in the brain. Cellular organization and behavior of the bombyxin producing cell system may be a simple model for understanding weakly-coupled multi-oscillator systems in vertebrates and invertebrates.
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