Matteo Rauzi - Institute of Biology Valrose - Keywords: development, tissue morphogenesis

Matteo Rauzi - Institute of Biology Valrose - Keywords: development, tissue morphogenesis

Contribution title: Probing an embryo-scale purse-string mechanism driving ventral furrow formation

Tissue morphogenesis is a process by which the embryo is reshaped into the final form of a developed animal. Tissues are constituted by cells that are interconnected one another: local changes of cell mechanical properties and shape drive consequent tissue shape change. Nevertheless the knowledge per se of the mechanisms and mechanics at the cell level which drive cell shape changes is insufficient to explain how tissues change their shape. Emerging properties arise at higher scales resulting from the interaction of cells within tissues and of tissues coordinating and interacting with one another. Studying this is a great challenge both technologically and conceptually. In this study we use the Drosophila embryo as a model system and focus on the process of tissue folding, process that is vital for the animal since folding defects can impair neurulation in vertebrates and gastrulation in all animals which are organized into the three germ layers. During Drosophila embryo development, the process of mesoderm invagination plays a fundamental and vital role since it allows translocating 600 cells inside the embryo where cells will eventually form inner tissues. Invagination impairment causes major embryo defects leading to a precocious animal death. The process of mesoderm invagination can be divided into three steps: 1) the ventral tissue, initially convex, flattens, 2) the tissue bends (furrow formation) and finally 3) the furrow displaces towards the interior of the embryo (furrow internalization). Most of the studies up to now have been modelling this system by capturing the dynamics visible on the embryo cross-section (view from which the curvature of the furrow is clearly visible). While these studies agree on how tissue flattening takes place, there is still much debate on what mechanism drives furrow formation and eventually furrow internalization. Our embryo-scale analysis reveals properties of the process that have not been considered previously. By using embryo mutations and mechanical manipulation, we propose to test an embryo-scale pursestring mechanism along the anterior-posterior axis of the embryo driving furrow formation.