| Project/Area Number |
11640680
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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 | OKAYAMA UNIVERSITY |
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Principal Investigator |
SAKAI Masaki Okayama Univ., Dept.Biol.Prof., 大学院・自然科学研究科, 教授 (30027502)
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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 |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | cricket / male / genitalia / mating / nerve / neuron / spermatophore / timer / 交尾行動 / 精包放出 / 神経 / 最終腹部神経節 |
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| Research Abstract |
To understand neural mechanisms of motor actions in the final stage of copulation in the male cricket, spike activity was recorded from motoneurons innervating muscles of the genital organs during spermatophore extrusion and subsequent transfer to the female. Each genital motoneuron was identified by axonal backfilling with nickel and cobalt. Spermatophore extrusion was caused by the simultaneous jerky contraction of four muscles of the dorsal pouch which was triggered by stimulation of mechano-sensilla in the epiphallus. On the other hand, spermatophore tansfer, in which the spermatophore is inserted into the copulatory chamber of the female, was achieved by the expansion of the two membraneous structure, the ventral lobes and median pouch, with the hemolymph. Extracellular recording indicated that dorsal pouch contraction was triggered by the spike discharge of a single motoneuron (mDP) in the terminal abdominal ganglion whose soma was located postero-laterally on the ventral side. mDP abruptly discharged at a rate up to 120Hz for several seconds in all or none fashion after the continuous stimulation of more than 10 seconds. For spermatophore transfer one motoneuron innervating one of the three epiphallus muscles started to discharge immediately after mDP fired while other two motoneurons innervating different muscles stopped discharging. These reciprocal activity resulted in opening the passages for the hemolymph to enter the ventral lobes and median pouch via the bending of the skeleton of the epiphallic complex. These results allowed us to examine the neural mechanisms of copulatory motor control and to speculate on the neural organization of the reproductive center for spermatophore extrusion and transfer.
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