Weisshaar Group - Research

The Weisshaar group brings to together a variety of biophysical interests. The unifying theme of our work is to bring quantitation to the field of light microscopy. We believe that using microscopy as merely an imaging modality is a waste of important information that can be obtained by analyzing the quantitative nature of of a micrograph. This quantitative information is in both the individual pixel counts and how these values change in time. There are three larger projects that our group works on, but they all utilize common techniques which allows us to work collaboratively. Click on the title of each project for more information.

Fusion

One area of research that we are interested in is studying the dynamics of vesicle fusion. We use our imaging techniques to quantify the dynamics and extent of fusion under different experimental conditions.

Bacteria

The space within living cells is often quite crowded and complex. To study and quantify the physical nature of these spaces we employ techniques of fluorescence microscopy. Our model system, Escherichia coli, is a Gram-negative bacterium. Unlike eukaryotes, prokaryotes do not have membrane bound organelles or a membrane enclosed nucleus. This, and their small size, have led some to claim that bacteria are merely sacks of biomolecules with little to no internal structure. This hypothesis has been largely discredited by careful studies by light and electron microscopists. Many of these studies have been unable to quantify dynamic properties of these complex media because their techniques often require fixing the cells and/or high doses of harmful radiation. We use the diffusion of tracer particles to study dynamics in these crowded and complex media. We use genetically encoded fluorescent proteins like GFP because they are easy to work with biologically.

How to measure diffusion in a bacteria (2)

PALM

Our final area of research is using the new high resolution fluorescent microscopy technique of photo activated localization microscopy (PALM) to gain insight into biological systems.