Switching of Reproductive Strategy in planarian

涡虫繁殖策略的转换

基本信息

批准号：
15370097
负责人：
HOSHI Motonori
金额：
$ 6.34万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Various metazoans can reproduce in multiple ways and select an alternative reproductive strategy such as asexual or sexual, and biparental or uniparental depending upon the environmental conditions and/or the phase of life cycle. However, the mechanism underlying the selection and switch of reproductive modes remains to be explored. Many freshwater planarians reproduce asexually by transverse fission as well as sexually by copulation. Asexual worms do not form any sexual organs, while sexual ones have hermaphroditic sexual organs and do not undergo fission. Some populations within the same species switch these reproductive modes seasonally.We have established an experimental system to analyze the mechanism underlying the switch from asexual to sexual reproduction in the planarian, Dugesia ryukyuensis. If the worms of an exclusively asexual clone (OH strain) of the species are fed with sexually mature worms of Bdellocephala brunnea, an exclusively sexual species, all of them gradually develop ovaries, testes and other sexual organs within a few weeks, and then copulate, and eventually lay cocoons filled with fertilized eggs. This suggests that sexually mature worms contain a putative sexualizing substance(s) that is not very genus-specific. The fully sexualized OH worms (acquired sexuals) produce their own sexualizing substance. The head fragments lacking the sexualizing substance regenerated into asexuals, though the other portions containing the sexualizing substance regenerated into sexuals. Thus, it is most likely that they keep the sexuality by producing enough an amount of the sexualizing substance. We are trying to identify the sexualizing substance in the acquired sexuals, and have so far clarified that it is acidic, heat-stable, smaller than 0.5 kDa and pronase-resistant. NMR analysis showed that L-trp is one of candidate for sexualizing substances

各种后生动物可以通过多种方式繁殖，并根据环境条件和/或生命周期的阶段选择一种替代性生殖策略，例如无性或性行为，以及两种或单亲。但是，生殖模式选择和转换的基础机制仍有待探索。许多淡水平面主义者通过横向裂变以及性交繁殖。无性蠕虫不会形成任何性器官，而性器官则具有雌雄同体的性器官，并且不会进行裂变。同一物种中的一些人群切换了这些季节性的这些生殖模式。我们建立了一个实验系统，以分析从普兰氏菌（Dugesia ryukyuensis）中从无性繁殖到有性繁殖的机制。如果该物种的独家无性克隆（OH菌株）的蠕虫被Bdellocephala brunnea的性成熟蠕虫喂食，这是一种独家性的性物种，它们逐渐在几周内逐渐发展出卵巢，睾丸和其他性器官，然后在几周内抚养，然后copulated吻，然后copulated养了肥大的卵子。这表明性成熟的蠕虫含有推定的性化物质，而不是很特定属。完全性的OH蠕虫（获得的性爱）会产生自己的性化物质。缺乏性化物质的头部碎片再生为无性恋者，尽管其他部分包含性化物质再生为性别。因此，他们很可能通过产生足够数量的性化物质来保持性欲。我们正在尝试确定所获得的性爱中的性化物质，到目前为止，它是酸性的，热稳定的，小于0.5 kDa且耐药性的。 NMR分析表明，L-TRP是性化物质的候选者之一