EXTERNAL SEMINAR - Alessandro De Simone (Université de Genève)

Alessandro De Simone (Université de Genève) will give a short external seminar, hosted by Alessandro Chiappori (IBDM).

Location: Hexagone
Date: 02.02.2026
Time: 1:30 PM

CENTURI is also providing for off-campus participants only a zoom link to attend the seminar: https://us02web.zoom.us/j/85941690095?pwd=Nm5NVGhESGlUbG1FMnZ2dU5vSlkxUT09

Meeting ID: 859 4169 0095
Secret Code: 002024

Title: Dynamic signalling in coordinating zebrafish scale regeneration

Abstract: In regeneration, a lost body part regrows to its original size, shape and structure. Regeneration poses fundamental questions regarding how chemical signals and mechanical cues are organized in time and space to control this process. In addition, how are signals and forces coordinated with the biophysical properties of the tissue environment? We investigate these questions with a quantitative approach that combines in vivo imaging of biosensors with measurements and theory. We apply these methods using the zebrafish scale as a model system. Scales are mm-sized bone disks that are accessible to live microscopy, as well as perturbations. The scale bone matrix is deposited by an adjacent monolayer of osteoblasts; after scales loss, osteoblasts regenerate completely in two weeks, through distinct phases of differentiation, proliferation and then hypertrophic growth. Dynamic Fgf/Erk signalling regulates both these processes of proliferation and hypertrophy. During the proliferative phase, Erk activity is uniformly high. At the transition from proliferation to hypertrophy, Erk switches off. Thereafter, osteoblast growth is driven by a series of excitable Erk activity waves that start at a central source and propagate out in concentric rings. I will present our results in investigating how Erk and other signals are patterned and control osteoblast transitions – first from a proliferative to a hypertrophic state, then to a state of arrested growth – as well as how they determine the scale final form. Overall, our research is contributing elucidating how signals are organized dynamically to orchestrate morphogenesis in regeneration.