Biology subjects

Merle, T.

Publications and source records attributed to Merle, T..

3 recordsLinked to original sources

bioRxiv2024

Compressive stress drives morphogenetic apoptosis

Tissues and organs are constantly submitted to physical stress, including compression, stretching, shear stress. The impact of compression due to overcrowding on cell extrusion has been the focus of recent studies. However, how tissue compression impact cell death in the context of morphogenesis is mostly unexplored. Here, we showed that a natural compression is exerted on the Drosophila developing leg by the surrounding tissue (or envelope) that is required for correct leg morphogenesis. In this tissue, apoptosis, preferentially localized in the future fold region, contributes to drive tissue folding through the generation of a pulling force on the apical surface. However, only a subset of these cells are dying within the expression domain of proapoptotic genes and how this precise pattern of cell death is established is totally unknown. We found that the natural compression exerted by the envelope contributes to the regulation of apoptosis, revealing that compression constitutes an integral part of apoptosis regulation during leg morphogenesis. We further reveal that compression drives a significant increase in lateral tension and favors apoptosis through the mechanosensor Piezo. Finally, perturbing cell cortex anchoring or membrane stiffness prove sufficient to block this process. Altogether, these results open new perspectives in term of mechanotransduction during morphogenesis.

developmental biology↗

bioRxiv2023

An easy-to-use microfluidic mechano-chemostat for tissues and organisms reveals that confined growth is accompanied with increased macromolecular crowding

Conventional culture conditions are oftentimes insufficient to study tissues, organisms, or 3D multicellular assemblies. They lack both dynamic chemical and mechanical control over the microenvironment. While specific microfluidic devices have been developed to address chemical control, they are often hard to use and do not allow the control of compressive forces. Here, we present a set of microfluidic devices which all rely on the use of sliding elements consisting of microfabricated rods that can be inserted inside a microfluidic device. Sliding elements enable the creation of reconfigurable sealed culture chambers for the study of whole organisms or model micro-tissues. By confining the micro-tissues, we studied the biophysical impact of growth-induced pressure and showed that this mechanical stress is associated with an increase in macromolecular crowding, shedding light on this understudied type of mechanical stress. Our mechano-chemostat is an easy-to-use microfluidic device that allows the long-term culture of biological samples and can be used to study both the impact of specific conditions as well as the consequences of mechanical compression.

biophysics↗

bioRxiv2020

Evolutionary Emergence of First Animal Organisms Triggered by Environmental Mechano-Biochemical Marine Stimulation

The evolutionary emergence of the first animals is thought to have been intimately associated to the formation of a primitive endomesodermal gut (i.e gastrulation) from ancestral multi-cellular spheres, blastulae, more than 700 million years ago. However, the biochemical cues having been at the origin of endomesoderm formation remain a mystery. Here we find that hydrodynamic mechanical strains developed by sea wavelets on pre-bilaterian Nematostella vectensis and pre-metazoan Choanoeca flexa representatives, which common ancestor dates back to more than 700 million years ago, can trigger gastrulation in a Myo-II dependent mechanotransductive process. Gastrulation in turn induces endomesoderm first biochemical specification through the mechanical activation of the {beta}cat pathway in pre-bilaterian Nematostella vectensis, like in Drosophila and zebrafish embryos, which common ancestor dates back to 600-700 million years ago. These observations converge to animal emergence that has been mechanotransductively triggered by wavelet mechanical strains on the sea-shore in multicellular choanoflagellates through Myo-II more than 700 million years ago, a process achieved in first metazoan through mechanosensitive Y654-containing {beta}cat evolutionary emergence found as conserved in all metazoan. One sentence summaryMarine hydrodynamic strains have activated first gastric organ formation from ancestral pre-animal cell colonies.

evolutionary biology↗