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The heterogeneity of agricultural produces leads to significant loss through the food chain and raises a challenge to the agroindustry. The corresponding key question in developmental biology is how an organ can achieve final robust size and shape in spite of the observed cell-to-cell variability, as exemplified by constant flower morphology in a given species. Growth processes in plants are heterogeneous and both biochemical and mechanical stimuli play a role in this regard. For example, fruit quality heterogeneity might arise from heterogeneity at flower induction and models explaining these phenomena are still lacking. Current models focus on average developmental trajectories; though fluctuations (variability) around this average values contain potentially essential information. In addition, cell-to-cell variability at the gene expression level is well acknowledged and starts to be assessed, while the feedback between cell and organ variability is still not clear. The aim of this project is to improve our understanding of such a stochastic behavior and thus to explain robustness of shapes despite its presence. I build models relating cells’ properties to the overall behavior of growing plant organs. Hypothesizing several cellular mechanisms and with the use of statistical physics tools, I relate it to the properties of the medium at larger scale. These models take as parameter the distribution of cells (the cell-to-cell variability), its inhomogeneity and its time changes. It integrates mechanics and signaling. With the help of live imaging, I aim to test several hypotheses for cell behavior and their consequence at the organ scale. For instance, measuring correlations among cells during development can shed light on coordination mechanisms 'constraining' these stochastic effects. This work helps to understand the robustness of organ morphogenesis and may provide the basis to select crops so as to obtain homogeneous products.
Graduated from a masters of theoretical physics, I oriented my research toward statistical physics entering in contact with Ken Sekimoto at the Ecole Supérieure de Physique et de Chimie Industrielle (ESPCI) to work on a set of microscopic objects called "Brownian Ratchet" and to find an unifying physical mechanism at play in this class of system. Afterward, I studied the collective behavior of the amoeba Dictyostelium Discoideum in its migration stage, with a view to enlighten how mechanical signals may allow the sensing of the external medium by individuals inside a cell aggregate and improve the locomotive action of those cells. I then started a post-doc with Rhoda Hawkins at The University of Sheffield. I proposed a simplistic model to understand how the cytoskeleton surrounding the nucleus is influenced by nuclear properties and its coupling to the extracellular medium. In Arezki Boudaoud’s team at ENS Lyon, I now find a stimulating work environment, surrounded by experimentalists as well as theoreticians. The AgreenSkills program allows me to develop my own research in the continuity of my scientific work.
Hervieux, N., Tsugawa, S., Fruleux, A. et al. & Hamant, O., 2017. Mechanical Shielding of Rapidly Growing Cells Buffers Growth Heterogeneity and Contributes to Organ Shape Reproducibility. Cur. Biol. 27(22):3468-3479.e4. Doi: 10.1016/j.cub.2017.10.033.
Fruleux, A., & Sekimoto, K., 2016. Mesoscopic formulas of linear and angular momentum fluxes. Phys. Rev. E 94(1-1):013004. Doi: 10.1103/PhysRevE.94.013004.
Fruleux, A., & Hawkins, R. J., 2016. Physical role for the nucleus in cell migration. Journal of Physics: Condensed Matter, 28(36):363002. Doi: 10.1088/09538984/28/36/363002.
Kawai R., Fruleux, A., ekimoto K., 2012 A hard disc analysis of momentum deficit due to dissipation Phys. Scr., 86 058508. Doi: 10.1088/00318949/86/05/058508.
Fruleux, A., Kawai, R., & Sekimoto, K., 2012. Momentum transfer in nonequilibrium steady states. Physical review letters, 108(16), 160601. Doi: 10.1103/ PhysRevLett.108.160601.