During normal development, signals between cells in the early embryo can have substantial influence on how the body develops, such as how the eyes and brain become localized in the head or how the spinal cord becomes localized on the back and not the belly. These early events have a tremendous effect on the organization of the tissues within the body and are critical for normal development of all animals. This project will determine how changes in early developmental mechanisms can lead to formation of new body parts. The three study animals are segmented worms, and offer the advantage that their embryos possess only 16 to 64 cells when these critical early signaling events occur. This contrasts with the approximately 1000 cells at a comparable stage 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 of this study are to identify the signaling cell and the molecules responsible for instructing surrounding cells to correctly position and generate body parts. The proposed study will provide strong STEM training opportunities by integrating scientific training with research for college students, graduate students and postdoctoral scholars. In addition, there will be ongoing community outreach activities, including hands-on activities with several different K-12 age groups in the local school districts to teach about animal biodiversity of the oceans, and general talks to adults in the local community.
This project seeks to understand how developmental changes lead to a range of body plans, and represents a unique opportunity to gain insight into the evolution of developmental programs. A group of animals known as the Spiralia exhibit enormous body plan diversity, yet many phyla in this clade share a highly stereotypic embryological program called spiralian development. This conservation allows studies of the evolution of homologous embryonic cell lineages with single cell resolution across diverse taxa. Specifically, the molecular signaling repertoire of a single cell will be determined, and the evolutionary plasticity of its organizing activity will be assessed by comparing distantly related species. Spiralian development will be investigated experimentally in the annelids Capitella teleta, Platynereis dumerilii and Chaetopterus sp. The phylogenetic position and embryonic studies of the three species will be used to reconstruct the ancestral cellular and molecular characteristics of annelid organizing activity. Specific goals of the project utilizing the three annelids are: 1) deletion of single cells in early stage embryos to identify cell(s) possessing 'organizing activity', 2) identification of molecular signals that mediate organizing activity, 3) determination of the function of organizing signals by knockdown and mis-expression studies. The proposed study will provide strong training opportunities by integrating scientific training with research, and continue to develop Capitella and Platynereis as annelid models for Evo-Devo studies. There will be ongoing community outreach activities, including hands-on activities with several different age groups in the local school districts that highlight biodiversity in the oceans, and general talks to adult audiences in the local community.
