Biology subjects

Quilliet, C.

Publications and source records attributed to Quilliet, C..

3 recordsLinked to original sources

bioRxiv2024

Geometry and cell wall mechanics guide early pollen tube growth in Arabidopsis thaliana

In Arabidopsis thaliana, successful fertilization relies on the precise guidance of the pollen tube tip as it navigates through the female pistil tissues to deliver non-motile sperm cells to ovules. While prior studies have unveiled the role of the pistil in directing pollen tubes to ovules, growth guidance mechanisms within the stigmatic epidermis during the initial phase of the pollen tubes journey remains elusive. A recent analysis comparing wild-type (WT) pollen tube paths in WT and ktn1-5 stigmatic cells revealed a tight connection between directed pollen tube growth and the mechanical properties of the invaded stigmatic cell. Building upon these observations, we constructed here a mathematical model to explore the mechanisms guiding early pollen tube growth through the papilla cell wall (CW). We found that in ktn1-5, the pollen tube moves freely on the curved papilla surface, following geodesics, while the WT papilla exerts directional guidance on the pollen tube. An order of magnitude analysis of the mechanical forces involved in pollen tube growth in papillae suggests a guidance mechanism, where the elongated papilla geometry and the CW elasticity combine to efficiently direct pollen tube growth towards the papilla base.

plant biology↗

bioRxiv2021

Embryo-scale epithelial buckling forms a propagating furrow that initiates gastrulation

Cell apical constriction driven by actomyosin contraction forces is a conserved mechanism during tissue folding in embryo development. While much effort has been made to better understand the molecular mechanisms responsible for apical constriction, it is still not clear if apical actomyosin contraction forces are necessary or sufficient per se to drive tissue folding. To tackle this question, we use the Drosophila embryo model system that forms a furrow on the ventral side, initiating mesoderm internalization. Past computational models support the idea that cell apical contraction forces may not be sufficient and that active or passive cell apico-basal forces may be necessary to drive cell wedging and tissue furrowing. By using 3D computational modelling and in toto embryo image analysis and manipulation, we now challenge this idea and show that embryo-scale force balance of the tissue surface, rather than cell-autonomous shape changes, is necessary and sufficient to drive a buckling of the epithelial surface forming a furrow which propagates and initiates embryo gastrulation.

developmental biology↗

bioRxiv2017

Asymmetric adhesion of rod-shaped bacteria controls microcolony morphogenesis

Bacterial biofilms are spatially structured communities, within which bacteria can differentiate depending on environmental conditions. During biofilm formation, bacteria attach to a surface and use cell-cell contacts to convey the signals required for the coordination of biofilm morphogenesis. How bacteria can maintain both substrate adhesions and cell-cell contacts during the expansion of a microcolony is still a critical yet poorly understood phenomenon. Here, we describe the development of time-resolved methods to measure substrate adhesion at the single cell level during the formation of E. coli and P. aeruginosa microcolonies. We show that bacterial adhesion is asymmetrically distributed along the cell body. Higher adhesion forces at old poles put the daughter cells under tension and force them to slide along each other. These rearrangements increase cell-cell contacts and the circularity of the colony. We propose a mechanical model based on the microscopic details of adhesive links, which recapitulates microcolony morphogenesis and quantitatively predicts bacterial adhesion from simple time lapse movies. These results explain how the distribution of adhesion forces at the subcellular level directs the shape of bacterial colonies, which ultimately dictates the circulation of secreted signals.

biophysics↗