Undergraduate Research | George R. Brown School of Engineering

Undergraduate Research | George R. Brown School of Engineering | Rice University

Undergraduate Research in Engineering at Rice

Nathan Spencer, Senior Bioengineering student
Assessing the Distribution of Lectin Binding in the Cochlea
with Dr. Robert Raphael
The surfaces of all cells are coated with complex carbohydrates, whose terminal sugar groups are important for specificity of cell adhesion and cell communication. Little is known about the distribution of these sugars in the cochlea. Lectins are plant-derived proteins that specifically bind to individual terminal sugars. The goal of my summer research was to assess the distribution of lectin binding in the cochlea.
In order to accomplish this, my summer work involved dissecting the guinea pig cochlea to isolate the organ of Corti and stria vascularis. The structures were fixed, cross-linking them in place, permeabilized to open the membranes so that fluorescent molecules could enter the cells, and labeled with conjugated lectins for an hour. The lectins I used were wheat germ agglutinin (WGA), concanavalin A (Con A), dolichos biflorus agglutinin (DBA), and peanut agglutinin (PNA); each is specific to a different terminal membrane sugar group. The preparations were colabelled with phalloidin in order to visualize the distribution of F-actin in lectin-labeled cells. F-actin outlines the cells, making it easier to identify which cells are labeled by the lectins. I used Confocal Microscopy, which has a filter that blocks the passage of light outside the specific plane of focus, giving clear images. I acquired stacks of confocal slices and put together three-dimensional reconstructions.
From this summer’s work, I found that WGA and DBA bind both the stereocilia and baso-lateral walls of hair cells. PNA favored the apical region of the lateral wall of outer hair cells and the basal half of Dieters’ cell phalanges. Con A only weakly labeled the stereocilia of hair cells. In the stria vacularis, WGA, DBA, and PNA bound the marginal cell region. WGA and Con A labeled the cell borders of marginal cells in the region of the junctional complexes. The patterns of WGA and Con A are consistent with previously published studies. Knowledge of lectin binding in the cochlea can be used to design methods for targeted drug delivery to cochlear cells and to perform micromechanical experiments.
I will be presenting an abstract on this work at the 2003 Midwinter meeting of the Association for Research in Otolaryngology in Daytona Beach, Florida.
Department of Bioengineering
Back to Undergraduate Research page

George R. Brown School of Engineering, Rice University grbsoe@rice.edu