Biology subjects

Guirao, B.

Publications and source records attributed to Guirao, B..

3 recordsLinked to original sources

bioRxiv2026

Tissue mechanics sets developmental scaling of collective cell migration

Despite substantial variation in adult size, animals within a species maintain consistent tissue patterns and shapes, a core property known as developmental scaling or size invariance. Developmental scaling has predominantly been attributed to the scaling of morphogen gradients and gene patterns to maintain positional information and cell fate specification1,2. However, development also necessitates collective cell flows that reshape tissues and reposition cells3,4. How these flows adapt to body size remains unclear. By combining quantitative live imaging, experimental perturbations, and physical modeling in the Drosophila thorax epithelium, we address this question in the context of a fundamental process: collective cell migration. We find that migration velocity scales linearly with tissue size, accounting for size-invariant cell positioning. While gene patterning scales with tissue size and modulates force generation, it is not sufficient to ensure proper velocity scaling. Instead, tissue mechanical properties govern the dependence of migration velocity on tissue size, enabling developmental scaling within the physiological range of animal sizes. These findings uncover principles and limits of size invariance by revealing how tissue mechanics sets the scaling behavior of collective cell flows with organismal size.

developmental biology↗

bioRxiv2022

Apical size and deltaA expression predict adult neural stem cell decisions along lineage progression

The maintenance of neural stem cells (NSCs) in the adult brain depends on their activation frequency and division mode. We use long-term intravital imaging of NSCs in the zebrafish adult telencephalon to link activation and division mode with predictive cellular and molecular parameters. We reveal that apical surface area and expression of the Notch ligand DeltaA predict NSC activation frequency, while deltaA expression marks NSC commitment to neurogenesis. We also find that deltaA-negative NSCs constitute the bona fide self-renewing NSC pool and systematically engage in asymmetric divisions generating a self-renewing deltaAneg and a neurogenic deltaApos NSC. Finally, modulation of Notch signaling during imaging indicates that the prediction of activation frequency by apical size, and the asymmetric divisions of deltaAneg NSCs, are functionally independent of Notch. These results provide dynamic qualitative and quantitative readouts of NSC lineage progression in vivo and support a hierarchical organization of NSCs in differently fated sub-populations.

neuroscience↗

bioRxiv2019

From heterogenous morphogenetic fields to homogeneous regions as a step towards understanding complex tissue dynamics

Within developing tissues, cell proliferation, cell motility, and other cell behaviors vary spatially, and this variability gives a complexity to the morphogenesis. Recently, novel formalisms have been developed to quantify tissue deformation and underlying cellular processes. A major challenge for the study of morphogenesis now is to objectively define tissue sub-regions exhibiting different dynamics. Here we propose a method to automatically divide a tissue into regions where the local deformation rate is homogeneous. This was achieved by several steps including image segmentation, clustering, and region boundary smoothing. We illustrate the use of the pipeline using a large dataset obtained during the metamorphosis of the Drosophila pupal notum. We also adapt it to determine regions where the time evolution of the local deformation rate is homogeneous. Finally, we generalize its use to find homogeneous regions for the cellular processes such as cell division, cell rearrangement, or cell size and shape changes. We also illustrate it on wing blade morphogenesis. This pipeline will contribute substantially to the analysis of complex tissue shaping and the biochemical and bio-mechanical regulations driving tissue morphogenesis. 1 Summary statementTissue morphogenesis is driven by multiple mechanisms. This study proposes a methodology to identify regions in the developing tissue, where each of the regions has distinctive cellular dynamics and deformation.

developmental biology↗