Tardigrades are a little-studied phylum of animals whose phylogenetic position makes them an ideal group for studies of how development evolves. The tardigrades are members of a clade that includes two of the most well-understood metazoan model organisms, Drosophila and C. elegans. They also share some of the key features of Drosophila or C. elegans that are useful to developmental biologists, including segment-like repeating body units and limbs, a small and reportedly constant cell number, and optically clear embryos. Despite this, very little is known about their development. The three most informative studies of tardigrade development were published before 1930, and there exists almost no developmental data from live embryos. For example, there is no fate map, nor even a rudimentary cell lineage. The Goldstein lab has begun to study tardigrade embryonic development. The goal is to test hypotheses regarding how cell lineage and cell fate specification have evolved, while providing the basic information required to make tardigrades a model system for studying evolution of development. Four-dimensional microscopy is being used to trace cell lineages and generate a fate map. Methods used for laser-ablation of individual cells in C. elegans are being extended to tardigrades to identify cell interactions that play roles in specifying cell fates. The long-term goal of this work is to contribute toward understanding how the developmental programs elucidated in model organisms have evolved to produce the morphological diversity found in nature.
Broader impacts resulting from the proposed activity (1) Discovery, understanding, teaching, training, learning: This research project will include training undergraduate students in scientific research, and each undergraduate student will attend an annual conference to present their findings. (2) Underrepresented groups: The principal investigator is a faculty mentor in UNC Chapel Hill's Research Education Support Program, which supports students from underrepresented minority groups to gain research experiences and to enroll in Ph.D. programs. (3) Research and education infrastructure: Live-embryo microscopy methods will be openly shared with other labs upon request. (4) Broad dissemination: As well as publishing results in scientific journals, a web page of films of tardigrade development will be constructed, similar to the Goldstein lab's widely-used C. elegans movies web page, for use as a freely-available educational material by others. (5) Benefits to society: This work will contribute to both the research and education missions of American universities, and any results of broad interest will also be disseminated at publication time through UNC Chapel Hill's news service.