Biology subjects

Dumond, M.

Publications and source records attributed to Dumond, M..

4 recordsLinked to original sources

bioRxiv2024

Highly expressed cell wall genes contribute to robustness of sepal size

Reproducibility in organ size and shape is a fascinating trait of living organisms. The mechanisms underlying such robustness remain, however, to be elucidated. Taking the sepal of Arabidopsis as a model, we investigated whether variability of gene expression plays a role in variation of organ size and shape. Previous work from our team identified cell-wall related genes as being enriched among the genes whose expression is highly variable. We then hypothesized that the variation of measured morphological parameters in cell-wall related single knockout mutants could be correlated with the variation in gene expression of the corresponding gene (the knocked-out gene) in wild-type plants. We analyzed sepal size and shape from 16 cell-wall mutants and found that sepal size variability correlates positively, not with gene expression variation, but with mean gene expression of the corresponding gene in wild type. These findings support a contribution of cell-wall related genes to the robustness of sepal size.

plant biology↗

bioRxiv2022

Robustness of organ morphology is associated with modules of co-expressed genes related to plant cell wall

Control of organ morphology is a fundamental feature of living organisms. There is, however, observable variation in organ size and shape within a given genotype. Taking the sepal of Arabidopsis as a model, we investigated whether we can use variability of gene expression alongside variability of organ morphology to identify gene regulatory networks potentially involved in organ size and shape determination. We produced a dataset composed of morphological parameters and genome-wide transcriptome obtained from 27 individual sepals from wild-type plants with nearly identical genetic backgrounds, environment, and developmental stage. Sepals exhibited appreciable variability in both morphology and transcriptome, with response to stimulus genes and cell-wall related genes displaying high variability in expression. We additionally identified five modules of co-expressed genes which correlated significantly with morphology, revealing biologically relevant gene regulatory networks. Interestingly, cell-wall related genes were overrepresented in two of the top three modules. Overall, our work highlights the benefit of using coupled variation in gene expression and phenotype in wild-type plants to shed light on the mechanisms underlying organ size and shape determination. Although causality between gene expression and sepal morphology has not been established, our approach opens the way to informed analysis for mutant characterization and functional studies.

plant biology↗

bioRxiv2021

3D Cell Neighbour Dynamics in Growing Pseudostratified Epithelia

During morphogenesis, epithelial sheets remodel into complex geometries. How cells dynamically organize their contact with neighbouring cells in these tightly packed tissues is poorly understood. We have used light-sheet microscopy of growing mouse embryonic lung explants, three-dimensional cell segmentation, and physical theory to unravel the principles behind 3D cell organization in growing pseudostratified epithelia. We find that cells have highly irregular 3D shapes and exhibit numerous neighbour intercalations along the apical-basal axis as well as over time. Despite the fluidic nature, the cell packing configurations follow fundamental relationships previously described for apical epithelial layers, i.e., Eulers formula, Lewis law, and Aboav-Weaires law, at all times and across the entire tissue thickness. This arrangement minimizes the lateral cell-cell surface energy for a given cross-sectional area variability, generated primarily by the distribution and movement of nuclei. We conclude that the complex 3D cell organization in growing epithelia emerges from simple physical principles.

cell biology↗

bioRxiv2018

Cellular heterogeneity in pressure and growth emerges from tissue topology and geometry

Cell-to-cell heterogeneity prevails in many biological systems, although its origin and function are often unclear. Cell hydrostatic pressure, alias turgor pressure, is essential in physiology and morphogenesis, and its spatial variations are often overlooked. Here, based on a mathematical model describing cell mechanics and water movement in a plant tissue, we predict that cell pressure anticorrelates with cell neighbour number. Using atomic force microscopy, we confirm this prediction in the Arabidopsis shoot apical meristem, a population of stem cells that generate all plant aerial organs. Pressure is predicted to correlate either positively or negatively with cellular growth rate depending on osmotic drive, cell wall extensibility, and hydraulic conductivity. The meristem exhibits one of these two regimes depending on conditions, suggesting that, in this tissue, water conductivity is non-negligible in growth control. Our results illustrate links between local topology, cell mechanical state and cell growth, with potential roles in tissue homeostasis.

biophysics↗