Experimental Soft Condensed Matter Group Harvard University, Prof. D. A. Weitz Cool Picture of the Moment

Actin and Microtubules are two filaments found in the cytoplasm of cells that are thought to be important for cell strength, motility, and organization. We are studying the local mechanical properties and the microstructure of fibroblast cells. Here we show a series of pictures taken by Heather Rose or Megan Valentine showing the microstructure of the cytoskelton using fluorescent dyes that tag either tubulin, the basic unit of the microtubule, or actin.

		The upper pictures show the microtubule structure in the cells. Microtubules can be seen throughout the cell, but appear densest near the nucleus, and provide an outline of the nuclear membrane.
		The lower pictures show the actin cytoskeleton. The actin is dense near the outer edge of the cell, and some actin bundles, probably stress fibers, can be seen stretching across the cell.

On the left, a DIC picture of a fibroblast cell. On the right, a similar cell to which we have introduced small fluorescent colloidal particles by endocytosis that move by Brownian motion and can be used to measure local mechanical response and microstructure.

Here is an overlay of red fluorescent particles and green-stained actin filaments. We can use pictures like these to measure the transport of the particles into cell and also to correlate local mechanics with structure.

Past cool pictures...