Séminaire du LPTMS : Antoine Fruleux (Ecole Polytechnique)

Fluctuations in biological tissues

Antoine Fruleux (École Polytechnique, LadHyX)

Biophysics — Modeling & Data analysis — Morphogenesis

Online seminar — Zoom Meeting ID: 991 9867 1888 — Passcode: ask L. Mazza and D. Petrov —

Figure 1: Cell growth is heterogeneous in space and time. Example of a sepal (green organ that protects a flower before it opens) from the model plant Arabidopsis thaliana. The colour scale corresponds to growth rates (high in red, low in blue).

The two hands of most humans almost superimpose. Similarly, flowers of an individual plant have
similar shapes and sizes. This is in striking contrast with growth and deformation of cells during
organ morphogenesis, which feature considerable variations in space and in time, raising the question
of how organs and organisms reach well-defined size and shape. In order to link cell and organ scales,
I built a stochastic hydrodynamic model of growing tissue with fibre-like structural elements that may
account for the plant cell wall or animal cytoskeleton or extracellular matrix [1]. The model gave two
important predictions. First, fluctuations occurring at cellular scale exhibit long-range correlations.
Second, the response of fibres to growth-induced mechanical stress may enhance or buffer cellular
variability of growth, making it possible to modulate the robustness of morphogenesis.
I will present in more details these results as well as a mathematical tool I defined to analyze signal
in tissues: the Cellular Fourier Transform (CFT) [2]. It is suited to those signals which can only be
defined at a cellular scale, or which are smoothed out of their sub-cellular variations, and it allows
to overcome the constrains met when studying biological tissue, foams, granular materials or other
geometrically disordered materials. I will introduce the method and explain how it reveals the physical
mechanisms setting spatial heterogeneity in growing tissues.

References

[1] Antoine Fruleux and Arezki Boudaoud. Modulation of tissue growth heterogeneity by responses
to mechanical stress. Proceedings of the National Academy of Sciences, 116(6):1940–1945, 2019.
[2] Antoine Fruleux and Arezki Boudaoud. Cellular fourier analysis for geometrically disordered
materials. Physical Review Research, 3(2):023036, 2021.


Date/Time : 11/05/2021 - 11:00 - 12:00

Location : LPTMS (100% online seminar)

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