We are pursuing three projects that extend from our interests in the development of tissues and the innovative application of light microscopy to biology: Developmental cell fusion, Second-harmonic generation microscopy, and Genome-wide imaging of C. elegans development.

Developmental cell fusion:

Formation of multinucleate syncytia (giant cells) is essential to the development and regeneration of human skeletal muscle, and is key to fertilization and the formation of various specialized cell types in many species. Yet the mechanism by which fusing cells recognize each other and merge their membranes is poorly understood. We use genetics and microscopy in the nematode worm C. elegans to study the mechanisms by which cells fuse during this animal's development. Our recent studies of the unique cell-fusion protein EFF-1 indicate that the molecular machinery of cell fusion has been re-invented during evolution of different cell types and divergent organisms. We are also investigating the mechanism of mammalian myoblast fusion, combining experimental tools developed specifically for that system with our experience from the study of C. elegans syncytia.

Second-harmonic generation (SHG) imaging:

We recently discovered that thick myosin filaments in the actomyosin lattice of striated muscle cells produce second-harmonic generation. This non-linear optical effect produces bright contrast from the endogenous unlabeled proteins themselves. The second harmonic light can be imaged at high three-dimensional spatial resolution on a microscope, yielding a digital profile of the arrangement and internal structure of muscle fibers in live tissue. We are applying SHG microscopy to the study of degenerative muscle diseases and aging, as well as the process of myofibrillogenesis in the differentiation of muscle cells.

Genome-wide imaging of C. elegans development:

We are working to develop a database of genome and proteome activity in the developing nematode C. elegans. This tiny yet complex animal is remarkable both for its transparency and the cell-by-cell invariance its developmental program. We plan to use two distinct fluorescence imaging technologies to record the dynamics of expression and localization of GFP-tagged gene products within live worms and embryos. The standardized digital data produced by these instruments will then be correlated to find genes and proteins that work coordinately in the formation of specific cell types and tissues.