Collaborative Proposal: Cellular and Molecular Dissection of "Organizing Activity" during Development in the Spiralia

在正常发育过程中，早期胚胎细胞之间的信号可以对身体的发育产生重大影响，例如眼睛和大脑如何定位在头部，或者脊髓如何定位在背部而不是腹部。这些早期事件对身体内组织的组织有巨大的影响，对所有动物的正常发育至关重要。该项目将确定早期发育机制的变化如何导致新身体部位的形成。这三种研究动物都是分节蠕虫，当这些关键的早期信号发生时，它们的胚胎只有16到64个细胞。这与脊椎动物胚胎在可比较阶段的大约1000个细胞形成对比。因此，将在单细胞水平上研究发育，并且可以在远亲动物中比较相似的细胞。这项研究的具体目标是确定信号细胞和负责引导周围细胞正确定位和生成身体部位的分子。这项研究将为大学生、研究生和博士后学者提供强大的STEM培训机会，将科学培训与研究相结合。此外，还将持续开展社区外展活动，包括在当地学区与几个不同的K-12年龄组开展实践活动，教授海洋动物生物多样性，以及与当地社区的成年人进行一般性谈话。该项目旨在了解发育变化如何导致一系列身体计划，并提供了一个独特的机会来深入了解发育计划的演变。一群被称为螺旋藻的动物表现出复杂的身体计划多样性，然而这个分支中的许多门都有一个高度定型的胚胎学程序，称为螺旋藻发育。这一保守性使得研究同源胚胎细胞谱系的进化成为可能。具体而言，将确定单个细胞的分子信号库，并通过比较远亲物种来评估其组织活动的进化可塑性。本文将对Capitella teleta、Platynereis dumerilii和Chaetopterus sp.的螺旋体发育进行实验研究。这三个物种的胚胎遗传位置和胚胎研究将用于重建环节动物组织活动的祖先细胞和分子特征。利用这三种环节动物的项目的具体目标是：1）删除早期胚胎中的单细胞以鉴定具有“组织活性”的细胞，2）鉴定介导组织活性的分子信号，3）通过敲低和错误表达研究确定组织信号的功能。这项研究将通过将科学培训与研究相结合，提供强有力的培训机会，并继续开发Capitella和Platynereis作为Evo-Devo研究的环节动物模型。将持续开展社区外展活动，包括与当地学区几个不同年龄组的实践活动，强调海洋生物多样性，并为当地社区的成年观众提供一般性讲座。

During normal development, signals between cells in the early embryo can havesubstantial influence on how the body develops, such as how the eyes and brainbecome localized in the head or how the spinal cord becomes localized on the back andnot the belly. These early events have a tremendous effect on the organization of thetissues within the body and are critical for normal development of all animals. Thisproject will determine how changes in early developmental mechanisms can lead toformation of new body parts. The three study animals are segmented worms, and offerthe advantage that their embryos possess only 16 to 64 cells when these critical earlysignaling events occur. This contrasts with the approximately 1000 cells at a comparablestage in the vertebrate embryo. Thus, development will be studied on the single cell level,and similar cells can be compared across distantly related animals. The specific goals ofthis study are to identify the signaling cell and the molecules responsible for instructingsurrounding cells to correctly position and generate body parts. The proposed study willprovide strong STEM training opportunities by integrating scientific training with researchfor college students, graduate students and postdoctoral scholars. In addition, there willbe ongoing community outreach activities, including hands-on activities with severaldifferent K-12 age groups in the local school districts to teach about animal biodiversityof the oceans, and general talks to adults in the local community.This project seeks to understand how developmental changes lead to a range of bodyplans, and represents a unique opportunity to gain insight into the evolution ofdevelopmental programs. A group of animals known as the Spiralia exhibit enormousbody plan diversity, yet many phyla in this clade share a highly stereotypic embryologicalprogram called spiralian development. This conservation allows studies of the evolutionof homologous embryonic cell lineages with single cell resolution across diverse taxa.Specifically, the molecular signaling repertoire of a single cell will be determined, and theevolutionary plasticity of its organizing activity will be assessed by comparing distantlyrelated species. Spiralian development will be investigated experimentally in theannelids Capitella teleta, Platynereis dumerilii and Chaetopterus sp. The phylogeneticposition and embryonic studies of the three species will be used to reconstruct theancestral cellular and molecular characteristics of annelid organizing activity. Specificgoals of the project utilizing the three annelids are: 1) deletion of single cells in earlystage embryos to identify cell(s) possessing 'organizing activity', 2) identification ofmolecular signals that mediate organizing activity, 3) determination of the function oforganizing signals by knockdown and mis-expression studies. The proposed study willprovide strong training opportunities by integrating scientific training with research, andcontinue to develop Capitella and Platynereis as annelid models for Evo-Devo studies.There will be ongoing community outreach activities, including hands-on activities withseveral different age groups in the local school districts that highlight biodiversity in theoceans, and general talks to adult audiences in the local community.