In vivo cytoskeletal dynamics of living fish embryos
In collaboration with Pat Wadsworth at UMass Amherst I have been studying the dynamics of the tiny fibers within each and every cell that gives the cell its shape, provides "railroad tracks" for the movement of vesicles from one part of a cell to another, and are involved in cell movements. Our approach has been to try to create embryos with fluorescent microtubules (panels A, B above) or microfilaments (panels C,D above) by injecting newly-fertilized eggs with a DNA plasmid for the tubulin or actin gene attached to the gene for green fluorescent protein (GFP). If and when the cells then express this DNA, their cytoskeleton will glow, allowing us to visualize these fibers. What is unique about our study is that we will be watching cells in an intact embryo. The killifish embryo is so exquisitely transparent that we can achieve images of a quality and resolution that used to be possible only with isolated cells crawling on glass.
For the following movies, we injected the GFP-actin plasmid
to label microfilaments. Using a Perkin-Elmer spinning disc laser confocal
microscope, we followed individual deep cell migration (for
differential interference contrast sequences of migrating deep cells,
pages linked here), as well as protrusive activity on the apical surface
of epithelial enveloping layer cells.
INDIVIDUAL MIGRATING DEEP CELLS