Arisaka, Katushi, David, Angela, Vincent, Nitin, Thatcher, Joseph, Chow, Aaron, Wang, Charles, Dao, Chris, Du, Angela, Alberto, Jasmine, Li, Lina
[
International Worm Meeting,
2017]
In contrast to previous behavioral experiments limited to two dimensional surfaces, we extended the study of C. elegans into three dimensional environments to observe the resulting unconstrained motion. While research has been initiated towards single worm, high magnification tracking, this has limited practicality in terms of gathering a large number of statistics with bulk behavior of many worms simultaneously. Incorporating stimuli allows for a new, more thorough examination of motion and environmental interaction, extending inquiry beyond simple free motion. Previously performed, two dimensional results suggest hypotheses, which may serve as limiting-case projections of greater trends in three dimensional space. A novel, cost effective system was developed to image C elegans' behavior over a period of 30 to 60 minutes using time lapse acquisition. The setup consists of three, perpendicularly oriented DSLR cameras, synchronized via the open source, MIT developed DigiCam control software and illuminated with lowly-invasive, conical, red LED light sources. Samples consisted of N2 type worms embedded in the center of 2% porcine gelatin (4 to 5 cm) quartz cuvettes. Each camera had an affixed aperture to elongate its depth of field, promoting focus throughout the volume of the cubes. In addition to free motion studies, three sets of Helmholtz coils (with axes coinciding with the cameras' optical axes) were utilized to generate a uniform magnetic field at the location of the sample. NaCl concentration gradients throughout the gelatin were also simulated and created for three dimensional chemotaxis experiments. Numerous free motion trials have been conducted alongside magnetic field experiments of field magnitude ranging from 0 Gauss (cancelling the geomagnetic field) to 10 Gauss. Using this data, analysis software tools were developed in MATLAB in order to extract the center of mass trajectory of worms navigating the gelatin, enabling further quantification of motional trends such as the worms' velocities and distributions of initial and final positions. While preliminary results for free motion (with chemical attractants) appear to reflect standard biased random motion, positive verification of magnetic field trials remains elusive.