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Hunt for early diverged stramenopiles and construction of taxonomic system

寻找早期分叉原生藻菌并构建分类系统

基本信息

批准号：
12440239
负责人：
INOUYE Isao
金额：
$ 8.83万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The following results were obtained during the period of this research :1. Undescribed two heterotrophic stramenopiles were discovered and reported as two new genera, Wobblia and Placidea. Molecular analyzes indicated these organisms diverged before emergence of the heterokont chromophytes, and that they form a clade independent from any known clades of the stramenopiles. A new class Placididea or Placidiophyceae was proposed.2. A new class of heterokont chromophytes, Pinguiophyceae, was proposed. This class is biochemically characterized : all the members so far known produce rich omega 3 fatty acids.3. Non-photosynthetic stramenopiles, Ptendomonas and Ciliophrys, were revealed to have chloroplast encoded gene rbcL. The gene was almost intact and unlikely a pseudogene. In Pteridomonas, the presence of vestigial chloroplast was confirmed with the electron microscope.4. Three orders of the class Dictyochophyceae were investigated with EM and molecular data (18S rDNA and rbcL). Taxonomic characters appeared in previously published articles were reevaluated based on cladistics of using morphological (LM and EM) and behavioral characters, and diagnostic characters of genera were considered. Practical guide for classification of Pedinellales genera was proposed.5. An amoeboid alga presumably a primitive member of the class Dictyochophyceae was discovered and examined. This organism formed a clade with Sulcochrysis described as incertae cedis. A proposal of a new order Sulcochrysidaies is under process.6. An amoeboid alga that produce biflagellate swimming cells in the life cycle was discovered. Comparison of this alga with other members of the Dictyochophyceae suggested that primitive state of the class was biflagellate and possession of typical stramenopile flagellar apparatus.The results obtained allowed to reconstruct character evolution presumably occurred in major clades of the stramenopiles.

本研究取得了以下成果：1.发现了两个尚未描述的异养层虫属，并报道为两个新属，Wobblia和Placidea。分子分析表明，这些生物分歧出现之前的异鞭毛有色植物，他们形成一个分支独立于任何已知的分支的层藻。提出了一个新纲-提出了一个新的异鞭毛型有色植物纲--珠母贝藻纲。这类生物化学特征：迄今已知的所有成员产生丰富的欧米茄3脂肪酸。3.在非光合的禾本科植物中，发现了叶绿体编码基因rbcL。该基因几乎是完整的，不太可能是假基因。在蕨类植物中，电子显微镜证实了退化叶绿体的存在.应用电镜和分子生物学技术（18 S rDNA和rbcL）对网枝藻纲的3个目进行了研究。利用形态学（LM和EM）和行为学特征的分支系统学方法，重新评价了以往文献中出现的分类特征，并考虑了属的诊断特征。提出了叉丝藻目各属分类的实用指南.一个变形虫状的寄生虫被发现并进行了检查，推测它是网枝藻纲的一个原始成员。这种生物与Sulcochrysis形成了一个分支，被描述为incertae cedis。一项关于Sulcochrysidaies新目的建议正在处理中。发现了一种在生活史中产生双鞭毛游泳细胞的变形虫。与网藻科其他成员的比较表明，该纲的原始状态是双鞭毛的，并具有典型的层状鞭毛器。所获得的结果可以重建可能发生在层状鞭毛主要分支中的性状进化。