Light-regulated collective contractility in a multicellular choanoflagellate

Abstract

Collective cell contractions that generate global tissue deformations are a signature feature of animal movement and morphogenesis. Nonetheless, the ancestry of collective contractility in animals remains mysterious. While surveying the Caribbean island of Curacao for choanoflagellates, the closest living relatives of animals, we isolated a previously undescribed species (here named Choanoeca flexa sp. nov.), that forms multicellular cup-shaped colonies. The colonies rapidly invert their curvature in response to changing light levels, which they detect through a rhodopsin-cGMP pathway. Inversion requires actomyosin-mediated apical contractility and allows alternation between feeding and swimming behavior. C. flexa thus rapidly converts sensory inputs directly into multicellular contractions. In this respect, it may inform reconstructions of hypothesized animal ancestors that existed before the evolution of specialized sensory and contractile cells.\n\nOne Sentence SummaryA newly described choanoflagellate species forms cup-shaped colonies that reversibly invert their curvature in response to light.