Department of Neuroscience
Associate Professor in the Department of Neuroscience
College of Medicine
Department of Neuroscience
1060 Carmack Road
Columbus OH 43210
Research Areas: The vertebrate brain is immensely complex, yet is wired with equally impressive precision. A fundamental goal in neuroscience is to understand the mechanisms that balance the huge number of cells with the intricacy with which they are connected. My lab is interested in the development of the vertebrate central nervous system, with a particular emphasis on the mechanisms involved in synapse and circuit formation. We study the roles played by cell-adhesion molecules in synapse formation and assembly, both in terms of potential roles in specificity and cell-cell recognition and in the detailed roles these molecules play in assembling synaptic junctions. Currently we focus on members of the cadherin superfamily, including the classical cadherins and the protocadherins.
Much of our work relies on in vivo two-photon laser-scanning time-lapse microscopy in living zebrafish embryos. Two-photon microscopy offers several advantages over conventional confocal imaging: 1) reduced photodamage and photobleaching, 2) increased fluorescence collection efficiency and 3) reduced light scattering of IR light allows deeper imaging in tissue. Zebrafish embryos are transparent and develop rapidly, allowing us to carry out time-lapse imaging of early developmental events with high spatial and temporal resolution.
Clustered Protocadherins: The protocadherins are a large group of neuronal cell-surface receptors (~100 in zebrafish) proposed to play a role in selecting appropriate synaptic partners. They are characterized both by the large number of isoforms, as well as the diversity of their extracellular domains. Zebrafish have four protocadherin clusters: an a and g cluster present on chromosome 10 and a second pair of a and g clusters present on chromosome 14. Each cluster consists of a tandem array of variable exons, each encoding an entire extracellular domain and a single-pass transmembrane domain. Each is spliced to three constant exons that, together, encode a short, common cytoplasmic domain. We are using BAC (Bacterial Artificial Chromosome) engineering technology (recombineering) to investigate the roles of these genes in neural development and synapse formation.
1) N-cadherin. We are investigating the role of N-cadherin in early synapse assembly, both in pre- and postsynaptic cells. Using two-photon time-lapse microscopy in conjunction with the expression of gene fusions of N-cadherin with genetically-encoded fluorescent proteins, we are characterizing the dynamics of N-cadherin within developing neurons, as well as its involvement in synapse formation and stabilization.
2) Type II classical cadherins. We have begun to look at type II cadherins, and their roles in CNS circuit formation, using BAC engineering and time-lapse microscopy.
Imaging: Two-photon laser-scanning time-lapse microscopy, image processing and image analysis.
Electron Microscopy: Ultra-thin sectioning, ultrastructural analysis and retrospective localization of recombinant transgenes.
Cell Biology: Transfection of cultured cells, immunocytochemistry, adhesion assays, Western blotting, antibody production.
Molecular Biology: Cloning of genes, GFP-tagging, expression, site-directed mutagenesis, isolation of promoters, BAC engineering
Zebrafish model system: transient gene expression, production of transgenics, antisense morpholino knockdown of gene expression.
The Scripps Research Institute, La Jolla, CA
Postdoctoral Training: Stanford University School of Medicine