Abstract
Haloarchaea thrive in extreme salinity, yet the mechanobiology governing their remarkable adaptability remains largely unexplored. In this thesis, we detail the discovery that uniaxial compression of Haloferax volcanii induces the formation of multicellular tissues. These archaeal tissues exhibit eukaryotic-like features, including a multinucleate pre-cellularization stage, junctional elasticity similar to that of animal tissues, and regulation of membrane fluidity. The tissues form two distinct cell types, central scutoid (Scu) cells and peripheral (Per) cells, characterized by distinguishable actin organization and patterns of protein glycosylation polarization. We found that this multicellularization occurs across 16 genera of haloarchaea. Understanding the physical processes behind the formation of these multicellular tissues is crucial for understanding their evolutionary significance. To further investigate the mechanobiological processes that underlie this phenomenon, we developed several tools and techniques, including a membrane fluidity probe called bSpoJ, a pipeline for identifying curvature-regulating proteins, and an inverted Traction Force Microscopy (TFM) approach to quantify tissue-generated forces. Using these techniques, we have established a systematic framework for studying the biophysics of haloarchaeal multicellularity, which lays the groundwork for understanding the evolution of multicellularity. The thesis concludes with a discussion of future directions for archaeal mechanobiology, highlighting open questions and yet unexplored paths in the field.