| Project/Area Number |
11480194
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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 |
Biophysics
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| Research Institution | HIMEJI INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
TSUDA Motoyuki HIMEJI INSTITUTE OF TECHNOLOGY, FACULTY OF SCIENCE, PROFESSOR, 理学部, 教授 (60045458)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAGAWA Masashi HIMEJI INSTITUTE OF TECHNOLOGY, FACULTY OF SCIENCE, ASSISTANT PROFESSOR, 理学部, 助手 (00212085)
岩佐 達郎 姫路工業大学, 理学部, 助教授 (00133926)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥14,200,000 (Direct Cost: ¥14,200,000)
Fiscal Year 2000: ¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 1999: ¥7,900,000 (Direct Cost: ¥7,900,000)
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| Keywords | ASCIDIAN LARVAE / BRAIN / PHOTOTAXIS / RHODOPSIN / BIOLOGICAL CLOCK / G-PROTEIN / GNRH / REPRODUCTION |
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| Research Abstract |
Since ascidians, a primitive chordate, spawn at a fixed latency period after sunrise, light must regulate a biological clock for reproduction in the ascidians. A retinal protein found in the cerebral ganglion of the ascidian is a candidate for the photoreceptor that drives the changes in gonadal activity of the gonadotropin-releasing hormone (GnRH) system. Photoresponses of the cerebral ganglion of ascidian, Halocynthia roretzi, were examined and two light-evoked responses recorded extracellularly, a light-evoked slow potential and light inhibition of high frequency spontaneous discharges. These results suggest that pacemaker signals of GnRH neurons are regulated by photoreceptor activation. Retinal proteins in the cerebral ganglion of the ascidian, Halocynthia roretzi, were successfully visualized and their localization was determined by the time-resolved fluorescence difference imaging method. Retinal proteins in the cerebral ganglion of adult Halocynthia roretzi, localized mainly at the surface of the anterodorsal root and the posterodorsal root. In the cross sections along the anteroposterio axis of the cerebral ganglion, the cells bearing retinal proteins were found in the peripheral cellular cortex mainly at the dorsal surface. Close localization of retinal protein and GnRH bearing cells suggests that retinal protein may trigger the biological clock for spawning in this ascidian.
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