2001 Fiscal Year Final Research Report Summary
| Project/Area Number |
10308033
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Developmental biology
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| Research Institution | Keio University (2000-2001)
Tokyo Institute of Technology (1998-1999) |
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Principal Investigator |
HOSHI Motonori Keio University, Foe. of Sci. & Tech., Prof., 理工学部, 教授 (20012411)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Midori Keio University, Foe. of Sci. & Tech., Associate Prof., 理工学部, 助教授 (00211574)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Planarian / Sexual reproduction / Asexual reproduction |
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| Research Abstract |
Asexual worms or an exclusively fissiparous strain (the OH strain) of the planarian Dugesia ryukyuensis keep developing hermaphroditic reproductive organs and eventually undergo sexual reproduction instead of asexual reproduction, namely fission, if they are fed with sexually mature worms of an exclusively oviparous planarian, Bdellocephala brunnea, suggesting that the sexually mature worms has a sexualizing substance(s) The fully sexualized worms no longer need the feeding on sexual worms to maintain the sexuality. Here, we demonstrate that the sexualized worms produce enough of their own sexualizing substance similar to that contained in B. brunnea. In case of surgical ablation of the sexualized worms, the fragments with sexual organs regenerate to become sexual, while those without sexual organs, namely head fragments, regenerate to return to the asexual state. The asexual regenerants from the sexualized worms are also fully sexualized by being fed with B. brunnea. Additionally, it was reported that head region in sexually mature worms lacks the putative sexualizing substance necessary fir complete sexualization (Sakurai, 1981). These results suggest that the fragments without sexual organ lack enough of an amount of the putative sexualizing substance and the sexuality is maintained by the sexualizing substance contained in the sexualized worms.
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