CAREER: Development of the Ascidian Peripheral Nervous System

脊椎动物进化的关键一步是发育出一个巨大的骨头骨，其中包含专门的成对感觉器官，使脊椎动物能够成为活跃的捕食者。脊椎动物的头部和成对感觉器官的相关细胞主要来自两类细胞，神经脊和颅骨安慰剂。尽管研究已经使人们更好地了解了神经脊和安慰剂在脊椎动物发育过程中是如何被指定的，但人们对它们的进化起源知之甚少。这项拟议的研究将通过检测海鞘幼虫周围神经系统(PNS)的发育来研究颅骨安慰剂的进化和胚胎学起源。海鞘动物是一种无脊椎动物，非常适合研究脊索特征的进化。幼虫三叉神经节由大约30多个细胞组成，主要是表皮感觉神经元，在形态上以及关键调控分子的表达模式上都与胎盘来源的感觉细胞相似。这项研究将确定PNS的细胞谱系和功能，并开始定义指定PNS在海鞘胚胎中发育的基因调控网络。研究生和本科生将率先使用三种技术来研究海洋无脊椎动物胚胎的发育：(1)基于转基因的细胞谱系分析；(2)通过毒素在细胞内的表达来选择性地杀死细胞；(3)使用RNA抑制技术进行体内基因功能测试。此外，还将使用比较基因组学方法、原位杂交、实时定量聚合酶链式反应和转基因胚胎分析来破译PNS基因调控网络。这些实验将为海鞘幼虫PNS和脊椎动物颅骨安慰剂之间的功能和基因调控相似性提供深入的见解。本项目将有助于PI作为教师-学者的发展。它包括面向本科生、研究生、研究生和小学学生和教师的教育课程。拟议的研究将主要由研究生和本科生进行。学生的研究将发表在科学期刊上，并将鼓励学生在科学会议上展示他们的发现。为本科生提供的一系列为期一年的研究机会，包括一个暑期项目，将为4到6名学生提供独立的项目，以及一个专注于发育生物学和实验技术的期刊俱乐部。新的实验方法将被纳入伍兹霍尔胚胎学课程中高级研究生和博士后研究员的关于海鞘发育的密集实验室/讲座部分。最后，将为小学生创建一个互动网站，为他们提供生物学研究的感觉。该网站将把实验室带入课堂，让年轻学生接触到参与科学研究的创造力和兴奋。这一创新计划将作为一个典范，鼓励其他实验室与小学课堂合作，为儿童提供更好的科学教育。

A key step in the evolution of vertebrates was the development of a large bony head containing specialized paired sensory organs that allowed vertebrates to become active predators. Vertebrate heads and the associated cells of the paired sensory organs are largely derived from two populations of cells, the neural crest and cranial placodes. Although research has led to a greater understanding of how neural crest and placodes are specified during vertebrate development, very little is known about their evolutionary origins. The proposed research will investigate the evolutionary and embryological origins of cranial placodes by examining the development of the ascidian larva peripheral nervous system (PNS). Ascidians are invertebrate chordates ideally suited for studying the evolution of chordate characteristics. The larval PNS, consisting of about three dozen cells that are primarily epidermal sensory neurons, shows similarities with placode-derived sensory cells both morphologically as well as in the expression patterns of key regulatory molecules. This research will determine the cell lineage and function of the PNS, and begin to define the gene-regulatory network specifying PNS development in the ascidian embryo. Graduate and undergraduate students will pioneer the use of three technologies to study marine invertebrate embryo development: (1) transgene-based cell-lineage analysis, (2) selective cell killing by the intracellular expression of a toxin and (3) in-vivo assays of gene function using RNA inhibition. Additionally, comparative-genomics approaches, in-situ hybridization, quantitative real-time PCR and analysis of transgenic embryos will be employed to decipher the PNS gene-regulatory network. These experiments will provide insights into the functional and gene-regulatory similarities between the ascidian larval PNS and vertebrate cranial placodes.This project will contribute to the development of the PI as a teacher-scholar. It incorporates educational programs for undergraduate, graduate, postgraduate and elementary school students and teachers. The proposed research will be performed primarily by graduate and undergraduate students. Student research will be published in scientific journals, and students will be encouraged to present their findings at scientific meetings. A series of year-long research opportunities for undergraduates, including a summer program, will provide 4 to 6 students with independent projects and a journal club focused on developmental biology and experimental techniques. New experimental approaches will be incorporated into an intense laboratory/lecture section on ascidian development for advanced graduate and postdoctoral fellows in the Woods Hole Embryology Course. Finally, an interactive Web site will be created for elementary-schoolstudents, providing them with a feel for biological research. The Web site will bring the laboratory into the classroom, exposing young students to the creativity and excitement involved in scientific research. This innovative program will serve as a model to encourage other laboratories to partner with elementary-school classrooms to provide improved science education to children.