Correlative X-ray Fluorescence Tomography and Multiphoton Imaging of Zinc in Developing Zebrafish Embryos

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

With this award, the Chemistry of Life Processes Program in the Chemistry Division supports Dr. Christoph J. Fahrni from the Georgia Institute of Technology to establish a multimodal imaging approach for the spatial correlation of Zn pools and areas of proliferating activities within developing zebrafish embryos. The imaging modalities utilized in the proposed work represent the forefront of current trace metal imaging research. Using a series of specifically optimized emission ratiometric fluorescent zinc probes, the 3D redistribution dynamics of labile zinc pools are visualized in live embryos by two-photon excitation microscopy (TPEM). In parallel, areas of mitotic activity are identified using a transgenic zebrafish line (zFucci), in which proliferating cells are expressing a fluorescent marker protein. At selected developmental stages, the total zinc distribution are also visualized by XRF tomography as recently implemented at the Advanced Photon Source of the Argonne National Laboratory. This multimodal imaging approach should provide for the first time direct insights into the redistribution dynamics of zinc pools and their role in the cell cycle progression during early embryogenesis. Zinc is an essential trace nutrient required for the vitality of all living organisms. It plays a central role in major cellular processes, and it is required for cell proliferation and critical to proper embryonic development. As the zinc requirements vary widely between organs, the embryo is most likely forced to redistribute the limited supply of trace nutrients in the course of development. Despite being of fundamental importance, the mechanisms governing zinc regulation and redistribution during development remain largely unexplored. Progress has been hampered in part due to the challenges associated with quantifying the distribution of zinc in situ. The combination of the three imaging modalities will allow to spatially correlate the location of labile Zn pools, the distribution of total Zn, and the cell-cycle progression, in a single embryo, and thus to elucidate the role of Zn in proliferating activities during embryogenesis. The multimodal imaging approach is expected to be readily adaptable for the investigation of a broad range of questions concerning Zn homeostasis during development. Dr. Fahrni will also work with Dr. John Cody at Wheeler High School in Marietta, Georgia to provide students with an opportunity to participate in a four-week summer program that would give them experience in a range of cutting-edge research techniques, including synthetic chemistry, spectroscopy, photophysics, and biological imaging. It is expected that this summer program will increase the enthusiasm of the students for further study in STEM-related fields. This award is being co-funded by the Physiological and Structural Systems (PSS) Cluster of the Integrative Organismal Systems (IOS) Division of the Biological Sciences (BIO) Directorate.