Shape classification of cells in wild-type MDCK cell monolayer.
a) Raw experimental data. b) - f) Minkowski tensor, visualized using ϑp and qp, Equation 7 (see Methods and materials) for p = 2, 3, 4, 5, 6, respectively. The brightness and the rotation of the p-atic director indicates the magnitude and the orientation, respectively. The visualization uses rotationally-symmetric direction fields (known as p-RoSy fields in computer graphics (Vaxman et al., 2016)).
Statistical data for cell shapes identified in Figure 1 (see Methods and materials).
a) Mean and standard deviation σ(qp) of qp. b) - f) Probability distribution function (PDF) of qp for p = 2, 3, 4, 5, 6, respectively. Kde-plots are used to show the probability distribution.
Schematic description of a two-dimensional object 𝒞 with contour ∂𝒞.
We denote the center of mass with xc and vectors from xc to points x on ∂𝒞 with r. The outward-pointing normals are denoted by n, the corresponding angle with the x-axis by θn.
For regular shapes, the corresponding magnitude of qp is always 1.0 and the detected angle is the minimal angle of the p-atic orientation with respect to the x-axis. Note that no shape with q2 = 1.0 is shown, as this would be a line. The visualization is according to Figure 1.
Illustrative description of the definition of q3 for an equilateral triangle.
Considering rotational symmetries under a rotation 120°= 2π/3 means that vectors with an angle of 120°or 240°are treated as equal. Applied to the normals n (left), this means that under this rotational symmetry the normals on the three different edges are equal. Mathematically this is expressed through resulting in the triatic director shown instead of the normals n (middle). One leg of the triatic director always points in the direction as the normal. While only shown for 3 points on each edge, we obtain an orientation with the respective symmetry on every point of the contour ∂𝒞. Considering the line integral along the contour provides the dominating triatic director, shown in the center of mass (right). To get a value between 0.0 and 1.0 for q3 we normalize this integral with the length of the contour, which corresponds to q0. As all triatic directors point in the same direction we obtain q3 = 1.0 in this specific example. To be consistent with other approaches we rotate the resulting triatic director by 60°= π/3 leading to the orange triadic director, which is the quantity used for visualization.
Defining p-atic order for deformable objects requires robust shape descriptors.
Shown is the strength of p-atic order for a polygon converging to an equilateral triangle. a) using qp and b) using γp. The considered vectors used in the computations, normals n of the contour for the Minkowski tensors and ri for γp, are shown. Note that the removal of the forth vertex highly influences the value of γp. How xc is calculated - as the mean of the vertex coordinates or as the center of mass of the polygon - can also slightly alter the results. We here used the described approach following Armengol-Collado et al. (2023).
a) Cell contour of the active vertex model. Red arrows represent the polarity vectors that set each cell’s instantaneous direction of self-propulsion. b) Zoom in on a vertex surrounded by three cells showing how the direction of self-propulsion on a vertex is calculated.
a) Cell contours of the multiphase field model. b) Corresponding phase field functions along the horizontal line in a). Colours correspond to the once in a).
Nematic (p = 2) and hexatic (p = 6) order are independent of each other.
q6 (y-axis) versus q2 (x-axis) for all cells in the multiphase field model (blue) and active vertex model (red). For each cell and each timestep we plot one point (q2, q6). Each panel corresponds to specific model parameters; Ca and v0 for multiphase field model, and p0 and v0 for the active vertex model, representing deformability and activity, respectively.
Nematic (p = 2) and hexatic (p = 6) order depend on activity and deformability of the cells.
Mean value for p = 2 (left) and p = 6 (right) as function of deformability p0 or Ca and activity v0 for active vertex model (a) and b)) and multiphase field model (c) and d)).
Coarse-gained nematic (p = 2) and hexatic (p = 6) order for R/Rcell = 8 depend on activity and deformability of the cells.
Mean value for p = 2 (left) and p = 6 (rigth) as function of deformability p0 or Ca and activity v0 for active vertex model (a) and b)) and multiphase field model (c) and d)).
a): Probability distribution functions (PDFs) using kde-plots, for q2 (yellow) and q6 (blue), once using the polygonal approximation of the cell shape and once using the detailed cell outline obtained from the microscopy pictures. b): q6 (y-axis) versus q2 (x-axis) for all cells from the experimental data in Armengol-Collado et al. (2023), once using the polygonal approximation of the cell shape (blue) and once using the detailed cell outline obtained from the microscopy pictures (red). For each cell and each timestep we plot one point (q2, q6).
On the left side a) we use the polygonal approximation of the cell shape, on the right side b) we use the detailed cell outline obtained from the microscopy pictures. Qp was calculated according to Equation 11, the averaging of this and the choice of R𝒞 follow the description in Coarse-grained quantities. The maximal coarse-graining radius corresponds to half the domain width. A logarithmic scaling was used for both axis. Error bars are obtained as s.e.m..
Mean value as function of deformability p0 and activity v0 for active vertex model.
a) nematic order (p = 2), b) hexatic order (p = 6).
We use only the polygonal approximation of the cell shape as γp can only work with polygons. Qp was calculated according to Equation 12, the averaging of this and the choice of R𝒞 follow the description in Coarse-grained quantities. The maximal coarse-graining radius corresponds to half the domain width. A logarithmic scaling was used for both axis. Error bars are obtained as s.e.m..
Values of the dimensionless parameters used in the active vertex model
Values of the dimensionless parameters used in the multiphase-field model simulations
PDFs for q3 using kde-plots, for varying deformability p0 or Ca and fixed activity v0.
Inlets show mean values of q3 as function of deformability. a) - d) active vertex model, e) - h) multiphase field model for decreasing activity.
PDFs for q4 using kde-plots, for varying deformability p0 or Ca and fixed activity v0.
Inlets show mean values of q4 as function of deformability. a) - d) active vertex model, e) - h) multiphase field model for decreasing activity.
PDFs for q5 using kde-plots, for varying deformability p0 or Ca and fixed activity v0.
Inlets show mean values of q5 as function of deformability. a) - d) active vertex model, e) - h) multiphase field model for decreasing activity.
PDFs for q3 using kde-plots, for varying activity v0 and fixed deformability p0 or Ca.
Inlets show mean values of q3 as function of activity. a) - d) active vertex model and e) - h) multiphase field model for decreasing deformability.
PDFs for q4 using kde-plots, for varying activity v0 and fixed deformability p0 or Ca.
Inlets show mean values of q4 as function of activity. a) - d) active vertex model and e) - h) multiphase field model for decreasing deformability.
PDFs for q5 using kde-plots, for varying activity v0 and fixed deformability p0 or Ca.
Inlets show mean values of q5 as function of activity. a) - d) active vertex model and e) - h) multiphase field model for decreasing deformability.
Mean value for p = 3 (left), p = 4 (middle) and p = 5 (right) as function of deformability p0 or Ca and activity v0 for active vertex model (a) - c)) and multiphase field model (d) - f)).
Shape classification of cells in wild-type MDCK cell monolayer.
a) Raw experimental data. b) - f) Polygonal shape classification, visualized using γp calculated by Equation 8 and Equation 9 for p = 2, 3, 4, 5, 6, respectively. The brightness and the rotation of the p-atic director indicates the magnitude and the orientation, respectively.
(a) Mean and standard deviation σ(| γp|) of |γp|. b) - f) Probability distribution function (PDF) of |γp| for p = 2, 3, 4, 5, 6, respectively. Kde-plots are used to show the probability distribution. For this first analysis we regard only one frame with 235 cells.
|γ6| (y-axis) versus |γ2| (x-axis) for all cells in the active vertex model.
For each cell and each timestep we plot one point (|γ2|, |γ6|). Each panel corresponds to specific model parameters p0 and v0, representing deformability and activity.
We use the polygonal approximation of the cell shape as γp can only work with polygons. a): Probability distribution functions (PDFs) using kde-plots, for |γ2| (orange) and |γ6| (blue). b): Nematic (p = 2) and hexatic (p = 6) order are independent of eachother. |γ6| (y-axis) versus |γ2| (x-axis) for all cells. For each cell and each timestep we plot one point (|γ2|, |γ6|).
Distance correlation dCor(q2, q6) between q2 and q6 for all cells in the multiphase field model (MPF - purple box) and active vertex model (AV - green box).
Each panel corresponds to specific model parameters; Ca and v0 for multiphase field model, and p0 and v0 for the active vertex model, representing deformability and activity, respectively. We compute one value for every timestep and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 × (Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles.
P-values of the distance correlation between q2 and q6 for all cells in the multiphase field model (MPF - purple box) and active vertex model (AV - green box).
Each panel corresponds to specific model parameters; Ca and v0 for multiphase field model, and p0 and v0 for the active vertex model, representing deformability and activity, respectively. We compute one value for every timestep and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 ×(Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles. 0.05 and 0.1 are marked with a grey dotted/grey dashed line to guide the eye.
Nematic (p = 2) and hexatic (p = 6) order depend on deformability of the cells.
Probability distribution functions (PDFs) for q2 (shades of orange) and q6 (shades of blue), using kde-plots, for varying deformability p0 or Ca and fixed activity v0. Inlets show mean values of q2 and q6 as function of deformability. a) - d) active vertex model, e) - h) multiphase field model for decreasing activity.
Nematic (p = 2) and hexatic (p = 6) order depend on activity of the cells.
Probability distribution functions (PDFs) for q2 (shades of orange) and q6 (shades of blue), using kde-plots, for varying activity v0 and fixed deformability p0 or Ca. Inlets show mean values of q2 and q6 as function of activity. a) - d) active vertex model and e) - h) multiphase field model for decreasing deformability.
versus for different coarse graining radii in the active vertex model.
Qp was calculated according to Equation 11, the averaging of this and the choice of R𝒞 follow the description in Coarse-grained quantities. The maximal coarse-graining radius corresponds to half the domain width. Each panel corresponds to specific model parameters; p0 and v0, representing deformability and activity. A logarithmic scaling was used for both axis. Error bars are obtained as s.e.m..
versus for different coarse graining radii in the multiphase field model.
Qp was calculated according to Equation 11, the averaging of this and the choice of R𝒞 follow the description in Coarse-grained quantities. The maximal coarse-graining radius corresponds to half the domain width. Each panel corresponds to specific model parameters; Ca and v0, representing deformability and activity. A logarithmic scaling was used for both axis. Error bars are obtained as s.e.m..
a) and the cell shapes used for the shape quantification, b) detailed cell outline obtained from the microscopy image, c) polygonal approximation of the cell shape. Shown for frame number 1.
Distance correlation dCor(q2, q6) between q2 and q6.
On the left side a) we use the polygonal approximation of the cell shape, on the right side b) we use the detailed cell outline obtained from the microscopy pictures. We compute one value for every frame and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 × (Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles.
P-values of the distance correlation between q2 and q6.
On the left side a) we use the polygonal approximation of the cell shape, on the right side b) we use the detailed cell outline obtained from the microscopy pictures. We compute one value for every frame and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 × (Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles. 0.05 and 0.1 are marked with a grey dotted/grey dashed line to guide the eye.
Distance correlation dCor(|γ2|, | γ6|) for the simulation data of the active vertex model.
Each panel corresponds to specific model parameters p0 and v0, representing deformability and activity. We compute one value for every timestep and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 × (Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles.
P-values of the distance correlation for the simulation data of the active vertex model.
Each panel corresponds to specific model parameters p0 and v0, representing deformability and activity. We compute one value for every timestep and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 × (Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles. 0.05 and 0.1 are marked with a grey dotted/grey dashed line to guide the eye.
versus for different coarse graining radii in the active vertex model.
Γp was calculated according to Equation 12, the averaging of this and the choice of R𝒞 follow the description in Coarse-grained quantities. The maximal coarse-graining radius corresponds to half the domain width. Each panel corresponds to specific model parameters; p0 and v0, representing deformability and activity. A logarithmic scaling was used for both axis. Error bars are obtained as s.e.m..
We use the polygonal approximation of the cell shape as γp can only work with polygons. We compute one value for every frame and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 × (Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles.
We use the polygonal approximation of the cell shape as γp can only work with polygons. We compute one value for every frame and present the resulting distribution with a box plot. In the box plots the orange line corresponds to the median of the data and the box ranges from the first to the third quartile of the data. The whiskers go from the lowest data point greater than (value of the first quartile) − 1.5 × (Interquartile range) to the highest data point below (value of the third quartile) + 1.5 × (Interquartile range). Outliers are shown with circles.