Phillips Group Homepage Caltech Website Home About Us Contact Us The Size of Things The Rate of Things DNA Science Advanced Class Projects Bootcamp 2005 Bootcamp February 2006 Bootcamp October 2006 Bootcamp June 2007 Bootcamp September 2007 APh162 2006 APh162 2007

Keratocyte Motility and Galvanotaxis

Keratocytes are the first line of defense when a Cyprinus' (fish/carp) outer scaled region is damaged. They essentially cover the outside of the fish; upon injury their connected network is broken. This break in the network is also accompanied by a small voltage, setup by the Keratocytes. They then follow the potential gradient to find the wound site. Julie Theriot and Eric Kalvins extracted these cells from a living goldfish (Galvin).

Galvin was very distressed...but was overall unharmed.

Their hypothesis was that the cells would exhibit isotropic motion when there was no potential gradient; but in the presence of an external potential the internal actin network would align with the field and polarize the Keratocytes' movement.

After the cells were extracted, Julie and Eric designed and built a small, microscope mounted, galavnotaxis chamber (not bad for two days). Pictured below is their third prototype. A small liquid viewing chamber was flanked by two electrodes connected to a programmable power source. The heat generated by the cell was removed with a very sophisticated heat transfer system...two small bags of ice.

Thus far, their hypothesis is certainly qualitatively correct. After some voltage calibration, they applied the following pulse to the cell, and collected video of the Keratocyte's corresponding motion. Notice the Keratocytes are at first moving rather randomly, but once the field is turned on they all proceed downwards.

Voltage across the cell as a function of time

Corresponding movie of Keratocyte motility/galvanotaxis.


Copyright Phillips Group 2005-2008