Dana García, Ph.D., Professor of Biology
Ever since high school, I’ve been interested in how cells communicate with one another using signaling molecules. As a graduate student in Beth Burnside‘s laboratory at the University of California at Berkeley, I was entranced by the potential of fish retinas as model systems for studying cytoskeleton, cell motility, and cell signaling. As a professor, I pursue my interest in those topics by studying how nerve cells in the retina communicate with the retinal pigment epithelial cells. In fish, the retinal pigment epithelium has long, apical projections which under daylight conditions fill with melanin pigment granules. In the dark, the pigment granules leave the apical processes and reside in the base of the cell around its nucleus. These movements are extensive, making them a good study system for understanding the signaling pathways and mechanical systems that regulate and execute organelle transport.
Richard Nuckels, Ph.D. student
Richard is interested in how fish genomes evolve through whole genome as well as segmental duplication. It is thought that following the divergence of the tetrapod lineage, the ancestors to ray-finned fishes underwent two rounds of whole genome duplication. Although many of the genes “born” as a consequence of those duplications have become pseudogenes, a surprisingly large number of pigmentation-related genes appear to be maintained as functional genes. Richard is using the myosin 5 gene family, which contains five members in fishes, to understand the consequences of these genome duplication events in terms of the maintenance of duplicates and the evolution of new functions for them.
Pedro “Pete” Gonzalez, Jr., M.S. student
Pete is testing the usefulness of zebrafish optic nerve as a model for studying changes in the central nervous system associated with aging. More specifically, Alexander is trying to determine whether the expression of glial fibrillary acidic protein (GFAP) by astrocytes in the optic nerve is an age-dependent process, since previous studies carried out on young adult zebrafish indicated that their optic nerve astrocytes expressed cytokeratin-based intermediate filaments and not GFAP-based intermediate filaments. This finding contrasts with glial cells in the retina, which do express GFAP. The banner image at the top of this web page shows Mueller glial cells of the retina expressing green fluorescent protein under a GFAP promoter. Pete’s longer term goal is to go to medical school so he can start a medical practice in the highly underserved Rio Grande Valley of Texas.
William Wilson, M.S. Biology student
William is using immunogold methodology to examine mouse retinas for the presence of MRP4. Will is taking advantage of the ability of antibodies to single out specific proteins in their natural location and bind to them. The antibody can then be detected with a second antibody which has an electron dense gold particle attached to it. The gold particles appear as little, black spheres when the tissue sections are examined by electron microscopy. Will won a SURF award which will support his and Tasha Roberts’ work.
Chelsea Loeffel, B.S. Biology student
Chelsea’s research focus is on light- and dark-adaptive changes in the retina of mice. Chelsea is using transmission electron microscopy to detect changes in pigment position in the retinal pigment epithelium. Her project is a continuation of work done by former student Sage Stone, who worked to develop a method for quantifying pigment position. Chelsea is examining retinas from light- and dark-adapted mice representing wild type and mutants lacking the cyclic nucleotide transporter Mrp4. Because cyclic AMP is known to be important in regulating pigment position in fishes, we hypothesize that mice lacking Mrp4 will show abnormalities in their pigment distribution.
Amanda Pattillo, B.S. Biology student
Amanda is working with Chelsea to determine whether MRP4 knock-out mice demonstrate normal pigment position in light- and dark-adapted retinas. She has become highly proficient at sectioning and imaging mouse retina using electron microscopy.
Melissa Esparza, B. S. Biology student
Melissa is continuing work on the “aging project” described above (see Pedro Gonzalez, Jr.). Melissa is an Honor’s student and will complete her thesis this fall.