权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Origin and evolution of echinoderm pentamery, a combined paleontological and molecular biological approach

棘皮动物五体的起源和进化，古生物学和分子生物学相结合的方法

基本信息

批准号：
05404001
负责人：
OJI Tatsuo
金额：
$ 9.98万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05404001/
关键词：
Echinoderms Evolution Molecular biology Development 5放射相称

项目摘要

Echinoderms constitute one of the invertebrate animal phyla that originated in the Cambrian and survived to the Recent seas. The phylum is characterized by the pentamerous symmetry in the adult body plan. The purpose of this project has been to clarify when and how this character evolved, as well as its functional significance, from the viewpoints of paleontology, embryology and molecular biology.1. Fossil records ; Because the late pre-Cambrian Tribrachidium has trimerous symmetry, some researchers consider that trimery presedes pentamery in echinoderms. However, it is dubious that Tribrachidium is an echinoderm. It is known that Cambrian echinoderms already had pentamerous symmetry. The pentamerous pattern of Cambrian echinoderms is in fact the '2-1-2 pattern', in which two of the three branches branches into two to make five branches. This pattern is wide spread in later echinoderms, therefore, it is reasonable to consider that the true pentamerous pattern evolved from the 2-1-2 pattern.2. Embryology ; In the development of echinoderms, pentamerous symmetry first appear when the water vascular system is formed and where the water vascular system is segmented into five projections. Detailed observation of the development of water vascular systems is therefore important to understand the mechanisms of the formation of pentamerous symmetry.3. Molecular biology ; It is not yet known what kind of genes control the formation of pentamerous body plan. From the known significance of homeogenes in body plan formation, it is not too much a speculation to consider that homeogenes are involved in the making of pentamery in echinoderms. In this study, DNA primers have been designed to PCR amplify a region of homeobox of some echinoids. As a result, some target DNA fragments have successfully amplified. The relationship between the expression of homeogenes and the formation of pentamery is now being investigated.

棘皮动物是起源于寒武纪的无脊椎动物门之一，并在近代海洋中生存。该门的特征是在成年人的身体平面五角对称。该项目的目的是从古生物学、胚胎学和分子生物学的角度阐明这种特征是何时以及如何进化的，以及它的功能意义。化石记录由于前寒武纪晚期的三臂虫具有三倍对称性，一些研究者认为棘皮动物的三倍对称性预示着五倍对称性。然而，Tribrachidium是棘皮动物是值得怀疑的。据了解，寒武纪棘皮动物已经具有五角对称性。寒武纪棘皮动物的五角模式实际上是“2-1-2模式”，即三个分支中的两个分支成两个分支，形成五个分支。这一模式在后来的棘皮动物中广泛存在，因此，我们有理由认为真正的五齿模式是从2-1-2模式进化而来的.胚胎学;在棘皮动物的发育过程中，当水维管系统形成时，即水维管系统被分割成五个突起时，首次出现五角对称。因此，详细观察水维管系统的发育对于理解五角体的形成机制非常重要。分子生物学：目前还不知道是什么样的基因控制着五角体的形成。从已知的同源基因在身体计划形成中的重要性来看，认为同源基因参与棘皮动物五配体的形成并不是什么太多的推测。本研究设计了一对DNA引物，对棘球蚴的同源盒基因进行了PCR扩增。结果，一些靶DNA片段成功扩增。同源基因的表达与五聚体形成之间的关系正在研究中。