1997 Fiscal Year Final Research Report Summary
Gene Control of Synaptic Transmission
| Project/Area Number |
08044245
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
神経・脳内生理学
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| Research Institution | Gunma University |
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Principal Investigator |
KIDOKORO Yoshiaki Gunma University School of Medicine Institute for Behavioral Sciences Professor, 医学部, 教授 (00053083)
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| Co-Investigator(Kenkyū-buntansha) |
UMBACH JA UCLA School of Medicine, 助手
GUNDERSEN CB UCLA School of Medicine, 助教授
SAITOE Minoru Gunma University School of Medicine Institute for Behavioral Sciences Professor, 医学部, 助手 (50261839)
YOSHIHARA Motojiro Gunma University School of Medicine Institute for Behavioral Sciences Professor, 医学部, 助手 (80222397)
GUNDERSEN Cameron.B UCLA School of Medicine Department of Pharmacology Associate Professor
UMBACH Joy A. UCLA School of Medicine Department of Pharmacology Assistant Professor
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| Project Period (FY) |
1996 – 1997
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| Keywords | csp mutants / Drosophila melanogaster / presynaptic Ca^<2+>channel / synaptic transmission / shibire mutant / synaptic vesicle iecycling / cysteine-string protein / Ca^<2+>influx / Ca^<2+>imaging |
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| Research Abstract |
Cysteine string proteins (csps) are synaptic proteins that are important for evoked neurotransmitter release at Drosophila neuromuscular junctions. In a temperature-sensitive csp mutant it has been reported that nerve-evoked synaptic potentials are not observed in non-permissive temperature while spontaneous synaptic potentials remain. When csp proteins were expressed together with Ca^<2+>channel proteins in Xenopus oocytes Ca^<2+>inward currents were greater than when Ca^<2+>channel proteins alone were expressed. Thus it has been speculated that csp proteins are interacting Ca^<2+>channels for Ca^<2+>influx at the nerve terminal. In this project we measured changes of Ca^<2+>concentration in the presynaptic nerve terminal during action potentials in 3rd instar larvae using a dye, Ca^<2+>Crimson AM.Upon repetitive nerve stimulation in csp mutant larvae Ca^<2+>signals were clearly detected at rcom temperature. However, at non-permissive temperature (32ﾟC) no signals were observed upon identical stimulation. In wild-type larvae Ca^<2+>signals were detected even at 32ﾟC.Therefore, we suggest that the normal functin of csp proteins is necessary for Ca^<2+>influx. Since csp proteins are on the synaptic vesicle membrane, synaptic vesicles have to be in the right position at the time of action potentia1 arrival. If there are no synaptic vesicles we expect no Ca^<2+>influx. To test this hypothesis we used another mutant, shibire, in which vesicle recycling is impaired at non-permissive temperature. In this mutant it has been shown that vesicles are depleted and no nerve evoked synaptic potentials are observed when the nerve was stimulated repetitively at non-permissive temperature. In this depleted condition no Ca^<2+>signals were observed at the nerve terminal upon repetitive nerve-stimulation. Thus, using two completely independent Drosophila mutants, we demonstrated that synaptic vesicles and csps are vital for the function of presynaptic Ca^<2+>channels.
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