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Automated characterization of cell shape changes during amoeboid motility by skeletonization.

Xiong Y, Kabacoff C, Franca-Koh J, Devreotes PN, Robinson DN, Iglesias PA - BMC Syst Biol (2010)

Bottom Line: The method uses skeletonization, a technique from morphological image processing to reduce a shape into a series of connected lines.We illustrate the algorithms on movies of chemotaxing Dictyostelium cells and show that our method makes it possible to capture the spatial and temporal dynamics as well as the stochastic features of the pseudopodial behavior.Thus, the method provides a powerful tool for investigating amoeboid motility.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.

ABSTRACT

Background: The ability of a cell to change shape is crucial for the proper function of many cellular processes, including cell migration. One type of cell migration, referred to as amoeboid motility, involves alternating cycles of morphological expansion and retraction. Traditionally, this process has been characterized by a number of parameters providing global information about shape changes, which are insufficient to distinguish phenotypes based on local pseudopodial activities that typify amoeboid motility.

Results: We developed a method that automatically detects and characterizes pseudopodial behavior of cells. The method uses skeletonization, a technique from morphological image processing to reduce a shape into a series of connected lines. It involves a series of automatic algorithms including image segmentation, boundary smoothing, skeletonization and branch pruning, and takes into account the cell shape changes between successive frames to detect protrusion and retraction activities. In addition, the activities are clustered into different groups, each representing the protruding and retracting history of an individual pseudopod.

Conclusions: We illustrate the algorithms on movies of chemotaxing Dictyostelium cells and show that our method makes it possible to capture the spatial and temporal dynamics as well as the stochastic features of the pseudopodial behavior. Thus, the method provides a powerful tool for investigating amoeboid motility.

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Individual pseudopods analysis. A-C. State and angle dynamics for pseudopods with consistent protrusions (A), consistent retractions (B) and protrusions followed by retractions (C). The movie was obtained courtesy of N. Andrew and R. H. Insall. The images show superimposed cell shapes (from the beginning of each pseudopod) and activity trajectories (red for protrusions, blue for retractions). The numbers represent the time (in seconds) from the beginning of the movie. The corresponding activity profiles relative to the chemoattractant gradient are plotted in D-F. In these plots red and blue dots represent protrusions and retractions, respectively, and the green lines join activities coming from the same pseudopod. G-J. The angle dynamics of all pseudopods superimposed by the directions of cell centroid (light-blue dots). Pseudopods with consistent protrusion pattern, consistent retraction pattern, protrusion followed by retraction pattern are highlighted in frame G-I, respectively. All the short-lived pseudopods are highlighted in J.
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Figure 5: Individual pseudopods analysis. A-C. State and angle dynamics for pseudopods with consistent protrusions (A), consistent retractions (B) and protrusions followed by retractions (C). The movie was obtained courtesy of N. Andrew and R. H. Insall. The images show superimposed cell shapes (from the beginning of each pseudopod) and activity trajectories (red for protrusions, blue for retractions). The numbers represent the time (in seconds) from the beginning of the movie. The corresponding activity profiles relative to the chemoattractant gradient are plotted in D-F. In these plots red and blue dots represent protrusions and retractions, respectively, and the green lines join activities coming from the same pseudopod. G-J. The angle dynamics of all pseudopods superimposed by the directions of cell centroid (light-blue dots). Pseudopods with consistent protrusion pattern, consistent retraction pattern, protrusion followed by retraction pattern are highlighted in frame G-I, respectively. All the short-lived pseudopods are highlighted in J.

Mentions: Despite huge differences in positions and sizes among the long-lived pseudopods, their protrusion/retraction state dynamics fall into three main activity patterns: consistent protrusions, consistent retractions, or alternating periods of protrusions and retractions (Figure 5 and Additional file 4). The average state persistence for this cell is 0.80, which means that pseudopods tends either to protrude or to retract during most of their lifetime. We observed that whether a pseudopod extends or retracts depends on the angle of the pseudopod relative to the chemoattractant gradient. Pseudopods near the front have higher probability of maintaining fast growth (Figures 5D, G). This probability decreases if the pseudopod drifts away from the front (Figures 5F, I). Similarly, the probability of retraction is low at the front of the cell, but increases as the pseudopod approached the back (Figures 5E, H). These observations are consistent with previous results [27,31].


Automated characterization of cell shape changes during amoeboid motility by skeletonization.

Xiong Y, Kabacoff C, Franca-Koh J, Devreotes PN, Robinson DN, Iglesias PA - BMC Syst Biol (2010)

Individual pseudopods analysis. A-C. State and angle dynamics for pseudopods with consistent protrusions (A), consistent retractions (B) and protrusions followed by retractions (C). The movie was obtained courtesy of N. Andrew and R. H. Insall. The images show superimposed cell shapes (from the beginning of each pseudopod) and activity trajectories (red for protrusions, blue for retractions). The numbers represent the time (in seconds) from the beginning of the movie. The corresponding activity profiles relative to the chemoattractant gradient are plotted in D-F. In these plots red and blue dots represent protrusions and retractions, respectively, and the green lines join activities coming from the same pseudopod. G-J. The angle dynamics of all pseudopods superimposed by the directions of cell centroid (light-blue dots). Pseudopods with consistent protrusion pattern, consistent retraction pattern, protrusion followed by retraction pattern are highlighted in frame G-I, respectively. All the short-lived pseudopods are highlighted in J.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2864235&req=5

Figure 5: Individual pseudopods analysis. A-C. State and angle dynamics for pseudopods with consistent protrusions (A), consistent retractions (B) and protrusions followed by retractions (C). The movie was obtained courtesy of N. Andrew and R. H. Insall. The images show superimposed cell shapes (from the beginning of each pseudopod) and activity trajectories (red for protrusions, blue for retractions). The numbers represent the time (in seconds) from the beginning of the movie. The corresponding activity profiles relative to the chemoattractant gradient are plotted in D-F. In these plots red and blue dots represent protrusions and retractions, respectively, and the green lines join activities coming from the same pseudopod. G-J. The angle dynamics of all pseudopods superimposed by the directions of cell centroid (light-blue dots). Pseudopods with consistent protrusion pattern, consistent retraction pattern, protrusion followed by retraction pattern are highlighted in frame G-I, respectively. All the short-lived pseudopods are highlighted in J.
Mentions: Despite huge differences in positions and sizes among the long-lived pseudopods, their protrusion/retraction state dynamics fall into three main activity patterns: consistent protrusions, consistent retractions, or alternating periods of protrusions and retractions (Figure 5 and Additional file 4). The average state persistence for this cell is 0.80, which means that pseudopods tends either to protrude or to retract during most of their lifetime. We observed that whether a pseudopod extends or retracts depends on the angle of the pseudopod relative to the chemoattractant gradient. Pseudopods near the front have higher probability of maintaining fast growth (Figures 5D, G). This probability decreases if the pseudopod drifts away from the front (Figures 5F, I). Similarly, the probability of retraction is low at the front of the cell, but increases as the pseudopod approached the back (Figures 5E, H). These observations are consistent with previous results [27,31].

Bottom Line: The method uses skeletonization, a technique from morphological image processing to reduce a shape into a series of connected lines.We illustrate the algorithms on movies of chemotaxing Dictyostelium cells and show that our method makes it possible to capture the spatial and temporal dynamics as well as the stochastic features of the pseudopodial behavior.Thus, the method provides a powerful tool for investigating amoeboid motility.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.

ABSTRACT

Background: The ability of a cell to change shape is crucial for the proper function of many cellular processes, including cell migration. One type of cell migration, referred to as amoeboid motility, involves alternating cycles of morphological expansion and retraction. Traditionally, this process has been characterized by a number of parameters providing global information about shape changes, which are insufficient to distinguish phenotypes based on local pseudopodial activities that typify amoeboid motility.

Results: We developed a method that automatically detects and characterizes pseudopodial behavior of cells. The method uses skeletonization, a technique from morphological image processing to reduce a shape into a series of connected lines. It involves a series of automatic algorithms including image segmentation, boundary smoothing, skeletonization and branch pruning, and takes into account the cell shape changes between successive frames to detect protrusion and retraction activities. In addition, the activities are clustered into different groups, each representing the protruding and retracting history of an individual pseudopod.

Conclusions: We illustrate the algorithms on movies of chemotaxing Dictyostelium cells and show that our method makes it possible to capture the spatial and temporal dynamics as well as the stochastic features of the pseudopodial behavior. Thus, the method provides a powerful tool for investigating amoeboid motility.

Show MeSH
Related in: MedlinePlus