1988 Fiscal Year Final Research Report Summary
Regulatory mechanism of spawning time in fishes
| Project/Area Number |
60480067
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | University of Tokyo |
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Principal Investigator |
AIDA Katsumi University of Tokyo, Faculty of Agriculture, 農学部, 助教授 (50012034)
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| Co-Investigator(Kenkyū-buntansha) |
FURUKAWA Kiyoshi University of Tokyo, Faculty of Agriculture, 農学部, 助手 (40134514)
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| Project Period (FY) |
1985 – 1986
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| Keywords | spawning / ovulation / GTH surge / carp / goldfish / メラトニン |
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| Research Abstract |
I. Regulatory mechanism of preovulatory GTH surge onset time (1) In the carp, it has been ascertained that the onset time of preovulatory GTH surge is determined by a photoperiodic cue. The onset time was also considered to be determined by circardian rhythm, since the ovulation also occurred at the period correspond to the night-time of the acclimation photoperiod (16L-8D) after changing photoperiod to continuous dark or light condition. (2) RIA for melatonin has been established and plasma melatonin levels were measured. Plasma melatonin levels were high during dark phase and low during light phase under both long and short photoperiods in the carp and goldfish. (3) Plasma GTH levels increased after electric stimulation of olfactory tract or brain in the goldfish.
II. Endocrinological analysis of spawning behaviour in both sexes. (1) Sexually matured female and male goldfish were transferred into a aqualium and ovulation was induced by a temperature increase from 12 to 20 C. Males with ovulatory females showed clear GTH surge coincidently with the preovulatory GTH surge in females. Males with non-ovulatory females failed to show GTH surge. (2) Olfactory tract sectioned (OTX) and sham operated (Sham) male goldfish were made. each male was paird with a matured female and ovulation was induced by temperature increase from 12 to 20 C. Males with ovulatory females showed clear GTH surge, whereas males with non-ovulatory females failed to show GTH surge. These results clearly indicate that pheromone is secreted into the water from ovulatory females and the GTH surge in males is induced by this pheromone through olfaction.
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