Tracking Molecular Motors Along Microtubules

An axon is a long narrow fiber that extends away from a nerve cell body and makes contact with other cells. In addition to serving as the wire for transmission of electrical signals from the nerve, the axon also provides a pathway for transport of molecular-scale cargo, such as mitochondria, lipids, proteins, and other organelles, to and from the nerve cell. Molecules called molecular motors carry cargo along a dense bundle of long parallel filaments inside the axon. We are interested in understanding the physical mechanism molecular motors use to transport cargo over long distances in the axon, and the role this plays in nervous system development. Our collaborators, Professors Peter Baas and Anand Rao at Drexel University, used fluorescence recovery after photobleaching (FRAP) microscopy to produce time-lapse movies of the movement of short microtubules along an axon. My research is to analyze the movement of the microtubules in an attempt to understand how the molecular motors transport them. Using the program ImageJ with the plug-in TrackMate, I can take the experimental images and analyze the microtubule’s movements over a time period. The plug-in TrackMate works by using detectors, filters and other parameters to identify bright spots in the image corresponding to an object, and tracking these bright spots from one frame to the next. This research may someday lead to innovations in Alzheimer’s disease and cancer because, with knowing how the motors are supposed to move, one can locate those that move irregularly