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

在正常发育过程中，早期胚胎细胞间的信号对身体的发育有重大影响，比如眼睛和大脑是如何在头部发育的，脊髓是如何在背部而不是腹部发育的。这些早期事件对体内组织的组织有巨大的影响，对所有动物的正常发育都至关重要。该项目将确定早期发育机制的变化如何导致新的身体部位的形成。这三种被研究的动物是分节的蠕虫，它们的优势在于，当这些关键的早期信号事件发生时，它们的胚胎只有16到64个细胞。这与脊椎动物胚胎中处于相同阶段的大约1000个细胞形成了对比。因此，发育将在单细胞水平上进行研究，相似的细胞可以在远亲动物之间进行比较。本研究的具体目标是识别负责指示周围细胞正确定位和生成身体部位的信号细胞和分子。本研究将为大学生、研究生和博士后提供强大的STEM培训机会，将科学训练与研究相结合。此外，还会有持续的社区外展活动，包括与当地学区几个不同的K-12年龄段的学生进行实践活动，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讲座。该项目旨在了解发育变化如何导致一系列身体计划，并为深入了解发育计划的演变提供了独特的机会。一组被称为螺旋体动物的动物表现出巨大的身体计划多样性，然而这个分支中的许多门都有一个高度刻板的胚胎学程序，称为螺旋体发育。这种保守性使得同源胚胎细胞系的进化研究具有跨不同分类群的单细胞分辨率。具体来说，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。本文将通过实验研究三种环节动物的螺旋体发育，通过对这三种动物的系统发育定位和胚胎研究来重建环节动物组织活动的祖先细胞和分子特征。该项目利用三种环节动物的具体目标是：1)在早期胚胎中删除单细胞以鉴定具有“组织活性”的细胞；2)鉴定介导组织活性的分子信号；3)通过敲低和错表达研究确定组织信号的功能。拟议的研究将通过将科学训练与研究相结合，提供强大的训练机会，并继续将Capitella和Platynereis作为进化- devo研究的环节动物模型。将会有持续的社区外展活动，包括在当地学区与几个不同年龄段的人进行的实践活动，强调海洋的生物多样性，以及在当地社区与成年观众进行的一般性演讲。

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.