Figures and data in Cortical flow aligns actin filaments to form a furrow

Version of Record: November 22, 2016
Version of Record: November 21, 2016
Accepted Manuscript: October 10, 2016

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Anne-Cecile Reymann

Fabio Staniscia

Anna Erzberger

Guillaume Salbreux

Stephan W Grill

(2016)
Cortical flow aligns actin filaments to form a furrow

eLife 5:e17807.

https://doi.org/10.7554/eLife.17807
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Figures
Videos
Tables

6 figures, 7 videos and 2 tables

Figures

Figure 1 with 1 supplement

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Flow and ingression during pseudocleavage and cytokinesis.

(a) Average active RhoA biosensor intensity profiles along the AP axis (0 represents the embryo center; N = 14 embryos for pseudocleavage and N = 7 for cytokinesis; errors represent the standard …
https://doi.org/10.7554/eLife.17807.005

Figure 1—figure supplement 1

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Details of actin organization during the polarization flow phase.

(a) Actomyosin gel dynamics in the *C. elegans* zygote. Single cortical and medial planes from a timelapse sequence of a representative embryo expressing both Lifeact::mKate2 and NMY-2::GFP. Anterior …
https://doi.org/10.7554/eLife.17807.006

Figure 2 with 5 supplements

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Cortical flows compress the gel to generate alignment.

(a) Filament orientation is quantified by a nematic order parameter; flow fields are obtained from Particle Image Velocimetry (PIV) analysis. (b) Gel flow, compression rate, filament orientation and …
https://doi.org/10.7554/eLife.17807.007

Figure 2—figure supplement 1

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Quantification methods developed.

(a) Example of the filaments alignment quantification (red lines) and the flow velocity field (yellow arrows), as well as nematic order parameters conventions. (b) Time evolution of flow (light …
https://doi.org/10.7554/eLife.17807.008

Figure 2—figure supplement 2

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Spatiotemporal correlations.

Plots of the spatiotemporal correlations between the compression, alignment and ingression data sets taken during the pseudocleavage stationary phase (a) and cytokinesis onset stationary phase (b). …
https://doi.org/10.7554/eLife.17807.009

Figure 2—figure supplement 3

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Nematic order parameter quantification of artificial images with and without directional bias.

(a) Example of a simulated isotropic actin meshwork (see Appendix for details). (b) Example of a simulated actin meshwork for which the angle of the starting direction is biased toward vertical (see …
https://doi.org/10.7554/eLife.17807.010

Figure 2—figure supplement 4

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Impact of image quality on the nematic order parameter quantification.

(a) An artificial filamentous network is obtained by a random iteration process with controllable parameters in Matlab (see Appendix for more details). (**b-d**) We chose to maintain a vertical bias in …
https://doi.org/10.7554/eLife.17807.011

Figure 2—figure supplement 5

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Comparison of different actin labeling strains and actin-binding protein localization.

(**a–c**) Average AP profiles of flow velocity (light green) and nematic order parameter (blue) at the time of stationary flow during pseudocleavage of respectively 22 embryos expressing Lifeact:GFP, …
https://doi.org/10.7554/eLife.17807.012

Figure 3 with 4 supplements

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Theory predicts an alignment peak.

(a) Schematic representation of flow-based alignment. For full theory refer to Appendix. (b) Average AP profiles of gel flow (light green, smoothened), compression rates (dark green) and nematic …
https://doi.org/10.7554/eLife.17807.015

Figure 3—figure supplement 1

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Influence of the gel material parameters for the nematic order parameter.

(a) Nematic order parameter profiles obtained when varying independently each of the fitting parameters $τ$ , $β τ$ , $ℓ$ away from their the best fit values obtained for cytokinesis. Dashed red line, best …
https://doi.org/10.7554/eLife.17807.016

Figure 3—figure supplement 2

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Contribution of active alignment to the nematic order parameter profile.

(a) Average AP profiles of gel flow (light green), compression rates (dashed dark green), nematic order parameter (blue) and myosin fluorescence (magenta) at the time of stationary flow during …
https://doi.org/10.7554/eLife.17807.017

Figure 3—figure supplement 3

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Ingression through anisotropic stress generation in the aligned gel.

(a) Top, a representative embryo is used to visualize the time course of ingression. Bottom, Kymograph obtained from the region specified by the dashed white box in the upper pannel. The …
https://doi.org/10.7554/eLife.17807.018

Figure 3—figure supplement 4

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Shape and ingression distance quantification.

Left column, plots of the cell shape (mean radius for all embryos during the stationary flow phase and eggshell reference) for pseudocleavage (a) and cytokinesis (b). Error bars, the standard error …
https://doi.org/10.7554/eLife.17807.019

Figure 4 with 2 supplements

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Flows and compression are required to generate alignment.

(**a-d**) Average AP profiles of gel flow (light green, smoothened), compression rates (dark green) and nematic order parameter (blue) at the time of stationary flow during pseudocleavage onset for *mlc-4*…
https://doi.org/10.7554/eLife.17807.022

Figure 4—figure supplement 1

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Cytoskeletal organization under RNAi perturbation.

(**a-d**) Actin organization and myosin distribution under *nop-1(RNAi)*, *ani-1(RNAi)* and *mlc-4*(*RNAi).* Inserts with fluorescence intensity profiles during pseudocleavage and cytokinesis onset are overlaid …
https://doi.org/10.7554/eLife.17807.023

Figure 4—figure supplement 2

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Flows, compression and alignment at cytokinesis onset.

(**a-d**) Results of *nop-1(RNAi), ani-1(RNAi)* and *mlc-4(RNAi).* Average AP profiles of gel flow (light green, smoothened), compression rates (dark green) and nematic order parameter (blue) at the time of …
https://doi.org/10.7554/eLife.17807.024

Figure 5

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Compression drives alignment for furrowing.

Schematic illustration of flows, cytoskeletal organization and cell shape changes during pseudocleavage and at the onset of cytokinesis.

https://doi.org/10.7554/eLife.17807.025

Author response image 1

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Actomyosin ring closure dynamics.
https://doi.org/10.7554/eLife.17807.029

Videos

Video 1

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posterframe for video — Actomyosin gel dynamics in the *C. elegans* zygote.

Cortical and medial planes of an embryo expressing both Lifeact::mKate2 and endogenous NMY-2::GFP. Left panel, medial plane Lifeact:mKate2, center, cortical NMY-2::GFP, right panel, cortical …
https://doi.org/10.7554/eLife.17807.003

Video 2

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Video 3

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Video 4

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Video 5

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Video 6

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Video 7

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Tables

Table 1

Best fit gel material parameters, bootstrapping. The median values together with the standard 68% confidence bounds of the distribution of the bootstrap data are given.

https://doi.org/10.7554/eLife.17807.020

	Pseudocleavage	Cytokinesis
	non RNAi	non RNAi
$τ$ , min	< 0.5 (n.d.) ^†	2.26 (1.89, 2.71)
$β τ$ , min	0.626 (0.577, 0.7)	0.646 (0.548, 0.713)
$ℓ$ , μm	4.72 (3.12, 6.09)	1.74 (1.37, 2.44)
	**nop-1 RNAi**	**nop-1 RNAi**
$τ$ , min	n.d. *	< 0.5 (n.d.) ^†
$β τ$ , min	n.d. *	0.771 (0.694, 2.75)
$ℓ$ , μm	n.d. *	2.67 (1.7, 11.5)
	**ani-1 RNAi**	**ani-1 RNAi**
$τ$ , min	< 0.5 (n.d.) ^†	0.989 (0.555, 1.79)
$β τ$ , min	1.45 (0.969, 18) ^‡	0.724 (0.636, 0.929)
$ℓ$ , μm	12.3 (6.39, 58.4) ^‡	3.38 (2.97, 6.16)
	**mlc-4 (5–7 hr) RNAi**	**mlc-4 (5–7 hr) RNAi**
$τ$ , min	< 0.5 (n.d.) ^†	4.76 (3.67, 6.6)
$β τ$ , min	0.467 (0.451, 0.503)	0.637 (0.567, 0.768)
$ℓ$ , μm	2.75 (2.38, 4.1)	6.58 (5.31, 6.85)
	**mlc-4 (7–9 hr) RNAi**	**mlc-4 (7–9 hr) RNAi**
$τ$ , min	n.d. *	< 0.5 (n.d.) ^†
$β τ$ , min	n.d. *	0.916 (0.82, 1.04)
$ℓ$ , μm	n.d. *	3.12 (2.49, 4.18)

*n.d. denotes parameters which could not be determined,
^†< 0.5 (n.d.) denotes parameters which could not be determined, but could be determined to be below 0.5 (see Figure 3—figure supplement 1b),
^‡denotes values that could be determined but that were not well constrained.

Table 2

Best fit gel material parameters, no bootstrapping. The mean values together with its 95% confidence bounds are given.

https://doi.org/10.7554/eLife.17807.021

	Pseudocleavage	Cytokinesis
	non RNAi	non RNAi
$τ$ , min	< 0.5 (n.d.) ^†	2.34 (1.74, 3.14)
$β τ$ , min	0.59 (0.513, 0.806)	0.652 (0.541, 0.764)
$ℓ$ , μm	5.38 (3.27, 8.85)	1.69 (1.04, 2.75)
	**nop-1 RNAi**	**nop-1 RNAi**
$τ$ , min	n.d. *	< 0.5 (n.d.) ^†
$β τ$ , min	n.d. *	0.738 (0.0.614, 0.862)
$ℓ$ , μm	n.d. *	1.79 (0.64, 5.03)
	**ani-1 RNAi**	**ani-1 RNAi**
$τ$ , min	< 0.5 (n.d.) ^†	1.01 (0.989, 1.03)
$β τ$ , min	1.31 (0.428, 2.19)	0.74 (0.588, 0.892)
$ℓ$ , μm	10.4 (4.91, 21.9) ^‡	4.08 (2.68, 6.2)
	**mlc-4 (5–7 hr) RNAi**	**mlc-4 (5–7 hr) RNAi**
$τ$ , min	< 0.5 (n.d.) ^†**	4.37 (3.08, 6.21)
$β τ$ , min	0.454 (0.437, 0.47)	0.614 (0.501, 0.727)
$ℓ$ , μm	2.24 (1.87, 2.67)	5.81 (5.02, 6.72)
	**mlc-4 (7–9 hr) RNAi**	**mlc-4 (7–9 hr) RNAi**
$τ$ , min	n.d. *	< 0.5 (n.d.) ^†
$β τ$ , min	n.d. *	0.97 (0.931, 1.01)
$ℓ$ , μm	n.d. *	2.98 (2.88, 3.08)

*n.d. denotes parameters which could not be determined,
^†< 0.5(n.d.) denotes parameters which could not be determined, but could be determined to be below 0.5 (see Figure 3—figure supplement 1b),
^‡denotes values that could be determined but that were not well constrained. Caption for Videos 1Videos 1 to 7