The central nervous system is a complex organ whose proper function is critical for coordination of locomotion, sensing and responding to environmental conditions, and is closely tied to animal survival. Understanding how such a complex organ develops represents a fundamental question in animal biology. Detailed cellular and molecular knowledge of neural development is limited to studies in model systems of two of the three major bilaterian clades, the ecdysozoans and deuterostomes. Capitella is a segmented worm and member of the third bilaterian clade, the lophotrochozoans. This project employs cellular, molecular and developmental approaches to characterize development of the centralized nervous system in this annelid model. Capitella offers several advantages for neurogenic studies, most notably that it undergoes both embryonic and adult neurogenesis, it exhibits robust adult regeneration and its genome has been fully sequenced. Early stages of brain development will be investigated using cell labeling methods, time-lapse video microscopy, and gene silencing techniques. The origin, specification, mode of internalization, and mitotic activity of neural progenitor cells of the Capitella nervous system will be determined. Molecular mechanisms controlling these processes will be analyzed using a combination of knockdown, mis-expression and pharmacological approaches. The project will provide crucial information of how the central nervous system is generated in polychaete annelids, fill a current gap in knowledge of the lophotrochozoans, and yield insights into the evolution of the centralized nervous system.
The results of this project are of interest to several fields of biology including neurobiology, developmental biology and evolutionary biology. In addition, the proposed work will refine and further methodology for studying gene function in the model Capitella. The project will integrate training with research and through a commitment by the PI to training in the laboratory environment. Women and underrepresented groups such as Pacific Islanders will be encouraged to participate in the nation's scientific enterprise. Results will be disseminated through peer-reviewed publications, conference presentations and outreach activities to the local community.
Nervous systems are critical for many aspects of animal life; they sense and respond to the environment, and control movement and behavior. Understanding how nervous systems develop and were elaborated upon during the course of evolution are fundamental questions in animal biology. The Spiralia are a large group of animals that include mollusks, annelids, nemerteans, brachiopods, among others. Compared to animals such as mice and fruit flies, the Spiralia have received little attention with respect to building an understanding of the mechanisms of how the adult and larval forms during development. In this project, we are currently investigating the formation of the components of the nervous system responsible for sensing the surrounding environment, including structures that can act as biosensors for disturbed habitats. Capitella teleta is a small marine worm, a member of the Spiralia, and suitable for studies of the nervous system. We have extensive knowledge of many aspects of the biology of Capitella, and we have pioneered several techniques in Capitella for our studies. The nervous system of Capitella includes a brain and ventral nerve cord (Picture 1), and there are a number of sensory structures in the head. Execution of the goals of this project has integrated research and training in the laboratory (Picture 2). For example, college students were involved in identifying additional molecular markers of the nervous system, one of our stated goals (Picture 3). In the lab, the students learned the development and anatomy of Capitella, advanced microscopy and imaging skills, molecular techniques, experimental design and trouble shooting skills through their participation in the project. Another goal was to investigate the question of whether the development of sensory structures is maintained across different stages of the life cycle. In Capitella, the eyes are a conspicuous, sensory structure in both larval and juveniles (Picture 4). The larval and juvenile eyes are thought to be separate structures, but it is unclear whether the larval eye is used to build the juvenile eye or if it is built de novo. To address whether these sensory structures are maintained in the juvenile after metamorphosis and become the adult sensory structures, we used an infrared laser to delete the larval eye (Picture 5). We found that the larval eye does not regenerate prior to metamorphosis, and does not reform in 7-day old juveniles, proving that formation of the adult eye is dependent upon the presence of the larval eye. These experiments involved training for a student working towards earning her masters degree. The principle investigator of the project participates in outreach activities with the local community, including general lectures to local volunteers (older adults), as well as presenting in a public lecture series (called ‘Evenings at Whitney’). To expose high school and college students to local marine invertebrate biodiversity, the PI participates in ‘touch tank’ visits to the marine lab, which often represents a first exposure to live marine animals. The PI leads the NSF-funded REU program (Research Experiences for Undergraduates) at the Whitney Laboratory, a STEM program designed to provide opportunities for college students to participate in scientific research during an 11-week intensive summer program (Picture 6).
