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Andrea's Project Page - RISE summer 2003 |
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Intern: Andrea Burbank, Stanford University
Mentor: Jennifer Ross
Faculty Supervisor: Deborah Kuchnir Fygensen
Department: Physics |
DIFFUSION IN MICROTUBULES
Microtubules are integral components of the cytoskeleton and form much of
the cell's framework. Hollow tubes of tubulin, they exist in the cytoplasm
of eukaryotic cells, providing them with structure and strength. With a
diameter of about 25 nanometers, microtubules are large enough to facilitate
transport of small molecules that diffuse in their interiors. Determining the
mechanism for and rate of this diffusion can have implications for drug
delivery as well as providing greater insight into the cell interior; the
anti-cancer drug taxol, for example, has been shown to diffuse in the
microtubule interior, binding reversibly to the dimers along its sides.
Using fluorescently marked compounds and a technique known as Fluorescence
Recovery After Photobleaching (FRAP), our work has focused on investigating
diffusion inside microtubules for molecules with various molecular weights
in an array of different circumstances. The relative rates of diffusion of
molecules in free solution and in loosely and tightly packed microtubule
bundles can provide insight into their modes of diffusion, whether in the
microtubule interior, in the interstices between bundled microtubules, or
in free solution between bundles. Analyzing these regions for diffusion will
further understanding of mobility within the cell and inform future efforts
for drug delivery.
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