VIDEO DATA ACQUISITION FOR MOVEMENT RESPONSES IN INDIVIDUAL ORGANISMS

Abstract— We describe a simple approach for the semiautomatic acquisition of data from video recordings of movement responses of microorganisms. For a sessile microorganism like Phycomyces blakesleeanus, we describe an angle transducer consisting of a precision rolary potentiometer and a transparent ruler. This device is placed in front of a video monitor during playback from a time‐lapse video recorder. The experimenter maintains the ruler parallel to the image of the upper region of the bending sporangiophore; a voltage proportional to the bending angle is directed to a strip‐chart recorder. The chart provides a continuous and precise graph of the bending angle as a function of time, so that the latency, bending rate, and other parameters may be readily measured. For motile microorganisms, such as Euglena gracilis, paths from video recordings are traced onto acetate sheets during playback. A rotary and a linear potentiometer convert the angle and length of successive path elements into analog voltages which are transmitted by analog‐to‐digital converters to a microcomputer for subsequent statistical and mathematical treatment. The general approaches presented here should be applicable to the study of movement responses of many types of organisms.