Abstract below

Rushikesh SHINDE

Active Fluids on Curved Surfaces

PhD supervised by Andrew Callan-Jones and Raphaël Voituriez

Abstract:

Epithelial tissues (thin layers of cells that cover our organs) or the actomyosin networks inside cells — Can be thought of as living materials. The actomyosin network is a molecular machine present inside cells, that allows cells to move and change shape by converting chemical energy (ATP) into mechanical work. When many such cells come together to form a tissue, these tiny molecular engines organize collectively, allowing the tissue itself to bend, flow, or change shape. Active hydrodynamics is a mathematical description that tries to capture the long-time fluid-like behavior of such a biological matter. A mathematical theory describing active fluids on curved surfaces had already been developed, since most biological tissues and cells naturally have curved shapes. In my thesis, I started from this existing theory and explored in detail how it behaves : In particular, how curvature affects the behavior of the active fluids. In addition to this theoretical work, we also collaborated with experimental biologists on two projects. In one, we studied how myoblast cells (the precursors of muscle cells) organize into chiral–helical structures on curved surfaces. In another, we examined how the actomyosin cortex — a thin active layer beneath the cell membrane — reorganizes right after fertilization in egg cells, and how this active fluid interacts with surrounding material to drive cell shape changes, thereby initiating embryogenesis.