1997 Fiscal Year Final Research Report Summary
Physiological studies on the physiological and behavioral changes after mating in the moth, Bombyx mori
| Project/Area Number |
08640870
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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 Univ.Fac. of Sci. Associate Professor., 理学部, 助教授 (50136420)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Bombyx mori / sex pheromone / mating / neurosecretory cell / neuropeptide / semen / inactivation / anesthesia. |
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| Research Abstract |
Suppression of pheromone production after mating in moths seems to be induced by a neural signal that originates from the abdomen and runs up the ventral nerve cord to inhibit the release of pheromonotropic neuropeptides. The present study demonstrated that the neurosecretory cells releasing the neuropeptides were most sensitive to mechanical stimulation and their firing activities were completely suppressed as soon as mating began. Thus, a mechanical signal induced by physical stimulation during copulation can trigger an inactivation mechanism of the neurosecretory cells. Because mating with a sterile male failed to induce permanent suppression of the cells. a temporal inhibition caused by mechanical stimuli may be released if they cannot receive another signal that may be induced by the sperm and /or testicular factors transferred from a fertile male. When semen obtained from the bursa copulatorix of a mated female were artificially injected into a female which already received tacti
… More
le stimulation from a sterile male, permanent suppression of pheromone production occurred, thereby indicating that the two-step inactivation mechanism of sex pheromone production is true in a mated female.A similar two-step inactivation mechanism has been inferred from observations of mated gypsy moth.Identification and mode of action of the putative-pheromonostatic male factor in Bombyx mori remain to be determined.
Pheromone production often resumed again in mated moths when the females were fixed to a platform after mating. Similar resumption of pheromone production were observed in the females which were anesthetized for 15 min in 95% CO_2 or for 1-2 min in etylether. The results suggest that the permanent suppressioncan be released under some stressful condition, such as restraint or anesthesia.
Virgin females of a mutant strain (XU20), which lay eggs without mating, had very low amount of sex pheromone but had large amonunt of PBAN activity in the extract of the brain-suboesophageal ganglion, thereby suggesting that the neurosecretory cells releasing pheromonotropic neuropeptides may be inactivated even in a virgin female. Less
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