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Directional locomotion of C. elegans in the absence of external stimuli.

Peliti M, Chuang JS, Shaham S - PLoS ONE (2013)

Bottom Line: Remarkably, this directional persistence is achieved despite a local orientation memory that decays on the scale of about one minute.This directional behavior requires sensory neurons, but appears to be independent of known sensory signal-transduction pathways.Our results suggest that long-range directional behavior of C. elegans may not be driven by sensory cues.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Developmental Genetics, The Rockefeller University, New York, New York, United States of America.

ABSTRACT
Many organisms respond to food deprivation by altering their pattern of movement, often in ways that appear to facilitate dispersal. While the behavior of the nematode C. elegans in the presence of attractants has been characterized, long-range movement in the absence of external stimuli has not been examined in this animal. Here we investigate the movement pattern of individual C. elegans over times of ∼1 hour after removal from food, using two custom imaging set-ups that allow us to track animals on large agar surfaces of 22 cm×22 cm. We find that a sizeable fraction of the observed trajectories display directed motion over tens of minutes. Remarkably, this directional persistence is achieved despite a local orientation memory that decays on the scale of about one minute. Furthermore, we find that such trajectories cannot be accounted for by simple random, isotropic models of animal locomotion. This directional behavior requires sensory neurons, but appears to be independent of known sensory signal-transduction pathways. Our results suggest that long-range directional behavior of C. elegans may not be driven by sensory cues.

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Directionality is independent of plate parameters.(A) Histogram of radial displacements (see Figure 2) for the entire data set (N  =  250 trajectories) acquired with the scanner-array set-up. (B) Relative direction Δθ of the paths of two animals assayed on the same plate in close succession. The direction of a path is defined as the direction of the end-to-end vector for the path. 0° corresponds to two paths that are parallel to each other, 180° to anti-parallel paths. N = 26 pairs. (C, D) End-to-end vectors of paths of animals started from intermediate positions between the center and the edge of a plate. (C): Freshly poured plates. (D): 12-day-old plates.
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pone-0078535-g003: Directionality is independent of plate parameters.(A) Histogram of radial displacements (see Figure 2) for the entire data set (N  =  250 trajectories) acquired with the scanner-array set-up. (B) Relative direction Δθ of the paths of two animals assayed on the same plate in close succession. The direction of a path is defined as the direction of the end-to-end vector for the path. 0° corresponds to two paths that are parallel to each other, 180° to anti-parallel paths. N = 26 pairs. (C, D) End-to-end vectors of paths of animals started from intermediate positions between the center and the edge of a plate. (C): Freshly poured plates. (D): 12-day-old plates.

Mentions: One explanation for directional persistence is migration towards an external signal. If this were the case, the distribution of path directions should reveal a bias towards a specific sector of the set-up. However, we did not detect such a bias (Figure 3A). Directionality could also arise in response to plate-specific cues. To test this, we examined the movement of individual animals placed sequentially on the same plate. As shown in Figure 3B, path orientations displayed no detectable correlation.


Directional locomotion of C. elegans in the absence of external stimuli.

Peliti M, Chuang JS, Shaham S - PLoS ONE (2013)

Directionality is independent of plate parameters.(A) Histogram of radial displacements (see Figure 2) for the entire data set (N  =  250 trajectories) acquired with the scanner-array set-up. (B) Relative direction Δθ of the paths of two animals assayed on the same plate in close succession. The direction of a path is defined as the direction of the end-to-end vector for the path. 0° corresponds to two paths that are parallel to each other, 180° to anti-parallel paths. N = 26 pairs. (C, D) End-to-end vectors of paths of animals started from intermediate positions between the center and the edge of a plate. (C): Freshly poured plates. (D): 12-day-old plates.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818405&req=5

pone-0078535-g003: Directionality is independent of plate parameters.(A) Histogram of radial displacements (see Figure 2) for the entire data set (N  =  250 trajectories) acquired with the scanner-array set-up. (B) Relative direction Δθ of the paths of two animals assayed on the same plate in close succession. The direction of a path is defined as the direction of the end-to-end vector for the path. 0° corresponds to two paths that are parallel to each other, 180° to anti-parallel paths. N = 26 pairs. (C, D) End-to-end vectors of paths of animals started from intermediate positions between the center and the edge of a plate. (C): Freshly poured plates. (D): 12-day-old plates.
Mentions: One explanation for directional persistence is migration towards an external signal. If this were the case, the distribution of path directions should reveal a bias towards a specific sector of the set-up. However, we did not detect such a bias (Figure 3A). Directionality could also arise in response to plate-specific cues. To test this, we examined the movement of individual animals placed sequentially on the same plate. As shown in Figure 3B, path orientations displayed no detectable correlation.

Bottom Line: Remarkably, this directional persistence is achieved despite a local orientation memory that decays on the scale of about one minute.This directional behavior requires sensory neurons, but appears to be independent of known sensory signal-transduction pathways.Our results suggest that long-range directional behavior of C. elegans may not be driven by sensory cues.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Developmental Genetics, The Rockefeller University, New York, New York, United States of America.

ABSTRACT
Many organisms respond to food deprivation by altering their pattern of movement, often in ways that appear to facilitate dispersal. While the behavior of the nematode C. elegans in the presence of attractants has been characterized, long-range movement in the absence of external stimuli has not been examined in this animal. Here we investigate the movement pattern of individual C. elegans over times of ∼1 hour after removal from food, using two custom imaging set-ups that allow us to track animals on large agar surfaces of 22 cm×22 cm. We find that a sizeable fraction of the observed trajectories display directed motion over tens of minutes. Remarkably, this directional persistence is achieved despite a local orientation memory that decays on the scale of about one minute. Furthermore, we find that such trajectories cannot be accounted for by simple random, isotropic models of animal locomotion. This directional behavior requires sensory neurons, but appears to be independent of known sensory signal-transduction pathways. Our results suggest that long-range directional behavior of C. elegans may not be driven by sensory cues.

Show MeSH
Related in: MedlinePlus