Developmental Mechanisms of Body Plan Evolution

身体计划进化的发育机制

• 批准号: 9900538
• 负责人: Rudolf Raff
• 金额: $ 30万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9900538&HistoricalAwards=false
• 关键词: Developmental; Mechanisms; Body; Plan; Evolution

Although there are several million species of animals, they fall into groups representing only 35 basic body plans (phyla). This proposal is to study development of the unusual body plan of adult echinoderms, which, because of the radical reorganization it has undergone, offers a unique model for body plan evolution. Echinoderms are related to chordates. Thier common ancestor was bilateral, but the echinoderm ancestor produced a new body plan by generation of its major body axis from the original ancestral left side. In addition, echinoderms evolved a pentameral, radial symmetry. The new body plan had to have involved a reorganization of development, and this is evident in the formation of the adult rudiment as an outgrowth of left-side tissues of the echinoderm larva. Unlike the model systems most used in studies of development, echinoderms transform their body plan in development, making a transformation from the bilateral symmetry of the larva to the pentameral radial symmetry of the adult. This developmental transformation parallels their evolutionary history. As the crucial steps in echinoderm evolution as well as in echinoderm development are the processes that produce left-right asymmetry and pentamery, the project will focus on these. Development of the echinoderm adult has been little studied. Heliocidaris erythrogramma, a sea urchin with a very large egg develops directly into a juvenile adult in only four days, and is highly amenable to study of adult development. The study will use the following approaches: (1) The mechanisms of development of the asymmetries will be studied by microsurgical techniques to investigate autonomous and local inductive interactions in this embryo. Tissue-specific gene markers will be used to analyze these processes in operated embryos. (2) The roles of regulatory genes involved in asymmetry generation in vertebrates will be investigated, and genes involved in development of asymmetry in H. erythrogramma identified. (3) The function of genes implicated in symmetry determination will be tested by over/ectopic expression experiments into appropriate cells of the H. erythrogramma embryo. The results of this project will provide an insight into the mechanisms that underlie evolutionary modifications of developmental processes, and will yield understanding of the development of asymmetries in embryos.

虽然有数百万种动物，但它们只代表35种基本的身体形态（门）。本研究的目的是研究棘皮动物成虫不同寻常的体表发育，由于其经历了彻底的重组，为体表进化提供了独特的模型。棘皮动物与脊索动物有亲缘关系。他们的共同祖先是双侧的，但棘皮动物祖先通过其主要身体轴从原始祖先的左侧一代产生了新的身体平面图。此外，棘皮动物进化出了五元体径向对称。新的身体计划必须涉及到发育的重组，这在棘皮动物幼虫的左侧组织的成体雏形的形成中是显而易见的。与发育研究中最常用的模型系统不同，棘皮动物在发育过程中改变了它们的身体计划，从幼虫的两侧对称转变为成虫的五边形径向对称。这种发育转变与它们的进化史相似。由于棘皮动物进化和发育的关键步骤是产生左右不对称和五聚体的过程，因此本项目将重点研究这些过程。对棘皮动物成虫的发育研究很少。红胆（Heliocidaris erythrogramma）是一种具有非常大的卵的海胆，仅在四天内就能直接发育成幼成体，非常适合研究成体发育。该研究将采用以下方法：(1)将通过显微外科技术研究不对称的发展机制，以研究该胚胎中的自主和局部诱导相互作用。组织特异性基因标记将用于分析手术胚胎中的这些过程。(2)研究脊椎动物不对称产生的调控基因的作用，并鉴定红红赤囊藻不对称发育的相关基因。(3)与对称性决定相关的基因的功能将通过在红红红细胞胚的适当细胞中进行过/异位表达实验来测试。该项目的结果将提供对发育过程的进化修改机制的深入了解，并将产生对胚胎不对称发育的理解。