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CeleST: Computer Vision Software for Quantitative Analysis of C. elegans Swim Behavior Reveals Novel Features of Locomotion

Figure 3

CeleST analysis reveals features of C. elegans swimming considerable individuality, gait preference, and reverse swimming.

A–C, C. elegans exhibit diverse swimming abilities, despite genetic and environmental homogeneity. CeleST can plot scores for two parameters against each other, for example: A, Travel speed vs. Asymmetry; B, Body wave number vs. Activity index; C, Brush stroke vs. Stretch. Data for WT 4-day old animals from 9 independent trials are plotted. D, C. elegans swim at specific wave initiation rates. We plotted in the form of line histograms the distribution of median Wave initiation rates (WIR) in wild-type animals as occurs over a 30 second interval. WIR values are binned to integers and the plot line delineates the contour of the bins in the histogram. X axis is median WIR, Y axis is the number of individuals exhibiting the indicated WIR. Data in this panel are combined to represent 3,372 animals ranging from 4 to 20 days old from 9 independent trials to emphasize the peaked distribution. Although animals in this large population do swim over the range of possible median WIRs (see Figure S1F for example), CeleST analysis reveals an unexpected bias for particular “gaits” in a subset of the population (about 14% total appear in favored WIRs). Older animals swim at lower median WIRs than young adult animals, but the preferred WIRs remain. WIR distributions for specific individual ages are depicted in Figure S1. Note that mean WIR rates do not exhibit a distribution bias (Figure S1F), so this study emphasizes the value of also considering median scores in swim behavioral analysis. E–G, For brief periods, swimming animals reverse, with the tail initiating the body wave. Reverse swimming is illustrated in Videos S3 and S4 on http://celest.mbb.rutgers.edu. In 4-day old animals, the glr-1(ky176) mutant, lacking a neuronal glutamate receptor, reversal frequency is increased relative to WT (E), although the trend to increased time spent in reverse is not statistically significant () (F). Unexpectedly, glr-1 mutants swim more symmetrically than WT at day 4 (G). from 3 independent trials for each strain. Data for all 10 measures, young and old age are shown in Figure S2. Error bars show SEM, **** .

doi: https://doi.org/10.1371/journal.pcbi.1003702.g003