ANALYZING MICROTUBULE MOTORS IN REAL-TIME

This chapter describes the basics of the computer-assisted video microscope setup and outlines some of the results obtained using the system. This relatively inexpensive computer-assisted program can analyze the movements displayed by video images in real time. The setup consists basically of a high-quality differential interference contrast (DIC) light microscope connected to a high-sensitivity, high-resolution video camera with externally controllable gain and black level. The output of the video camera is mixed with the output of a computer, resulting in a superimposed video image of both the light microscope sample and the computer screen. By control of the position of the computer cursor with the “mouse,” the position and velocity of moving microtubules can be measured in real time at relatively low cost. Moreover, with the proper optics and video enhancement, it is possible to clearly observe individual microtubules under the light microscope without the need for additional digital image enhancement. This real-time system for analysis of microtubule motility has proved to be an extremely useful and potentially versatile system for a number of applications such as to characterize sea urchin egg kinesin-driven motility, for the detailed characterization of a number of mechanoenzymes, and for measurements of cellular growth and chemotaxis. © 1993, Elsevier Science Publishers, B.V.