The phylum Cnidaria is a group of gelatinous, primarily marine animals that includes jellyfish, corals, and sea anemones. Most cnidarians are structurally simple and have radial symmetry. One reason that cnidarians are important is that they are the closest relatives of all bilaterally symmetrical animals, a group that includes insects, worms, and vertebrates. Because of this, studying the molecular or cellular basis of a biological trait in a cnidarian allows biologists to infer how that trait might have functioned in the ancestors of cnidarians and bilaterians. This, in turn, can help scientists understand how the trait currently functions in more complex animals, including humans. In this project, the research team will develop tools to study how genes function in a cnidarian model organism called Hydractinia. Hydractinia is an ideal model organism because it is inexpensive and easy to maintain, and not restricted by ethical considerations. In addition, Hydractinia is a model for many processes that are interesting to biologists studying more complex organisms, including regeneration, stem cell maintenance, and the rejection of transplanted tissues. The goal of this project is to allow biologists to study any Hydractinia gene in any cell type at any spatial location and at any timepoint during the animal's life. The tools developed in this project will be paired with rapid dissemination efforts, including the sharing of protocols and materials with the broader scientific community. In addition, the principal investigators and their teams share a strong commitment to education and outreach activities, and have planned creative methods to engage people, including K-12 students and the general public.
Cnidarians are morphologically simple animals and the closest relatives of bilaterians. As such, they are key to understanding the evolutionary origin of many bilaterian features. Despite the availability of some functional genomics tools in a few cnidarians, it is not currently possible to control gene expression at the level of cell type or temporal/spatial location. This is particularly problematic for the study of genes for which overexpression or knockdown/knockout is embryonic lethal, and for studying context-specific gene function. Moreover, due to the diversity of cnidarian characters, it is either difficult or impossible to study many cnidarian traits, including coloniality, morphological polymorphism, allorecognition, and stem cell pluripotency in existing cnidarian model species that lack these features. This project aims to develop cell type-specific functional genomics in the hydrozoan Hydractinia symbiolongicarpus. Work in Aim 1 will focus on generating an atlas of gene expression for all adult Hydractinia cell types, using single-cell RNAseq data, followed by identifying and validating exclusive cell type markers and generating transgenic reporter animals for as many cell types as possible. Work in Aim 2 will develop a recombinase-based conditional gene knockout system including strains that permit cell type-specific recombinases and strains for conditional alleles in Hydractinia. A diverse set of activities have been planned to rapidly disseminate the tools and techniques resulting from this project to the broader scientific community.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
