2006 Fiscal Year Final Research Report Summary
ANALYSIS OF INSECT CIRCADIAN ORGANIZATION BY IDENTIFICATION OF OPTIC LOBE CLOCK NEURONS
| Project/Area Number |
16370037
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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 |
Animal physiology/Animal behavior
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| Research Institution | OKYAMA UNIVERSITY |
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Principal Investigator |
TOMIOKA Kenji OKAYAMA YUNIVERSITY, GRADUATE SCHOOL OF NATURAL SCIENCE AND TECHNOLOGY, 大学院自然科学研究科, 教授 (30136163)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Akira KYUSHU UNIVERSITY, Research and Development Center for Higher Education, Assistant, 高等教育総合開発研究センター, 助手 (40229539)
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| Project Period (FY) |
2004 – 2006
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| Keywords | insect / circadian clock / clock neuron / clock gene / neural mechanism / circadian rhythm / RNA interference / optic lobe |
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| Research Abstract |
We have investigated the neural mechanism controlling circadian locomotor rhythm in the cricket and obtained the following results.
1)Candidate clock neurons, so-called outer chiasma neurons (OCN) innervated the lamina and had two types of circadian electrical activity rhythm, peaking either during the subjective day or during the subjective night.
2)We have cloned the clock genes, period, timeless, clock, doubletime, and determined their whole or partial nucleotide sequence. These genes had relatively high homology of amino acid sequences with those counterparts of Drosophila. mRNAs of per, tim showed a circadian change, peaking during the mid subjective night. Both per and tim were daily expressed in various tissues and this was controlled by the circadian clock in the optic lobe.
3)Crickets became arrhythmic after injection of per dsRNA into the abodomen. In these arrhythmic crickets per mRNA levels were reduced by about 75% compared with those intact crickets.
4)With in situ PCR using a per specific primer set, a group of cells at the outer chiasma region were labeled. We still need careful reinvestigation, but these cells are the most likely candidate of clock neurons.
5)Results of behavioral experiments suggested that the clock neurons at outer chiasma have some contact with other efferent neurons, and that the output neurons have synaptic contact with descending neurons in the ipsilateral brain hemisphere.
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