Molecular and cellular mechanisms of multicellular animals to flexibly construct complex bodies according to the environment

In contrast to the traditionally known developmental mechanisms in which cells are “components” to form tissues and external shapes of organisms, we revealed the conceptually different mechanism of morphogenesis in which cells act as “builders” to produce, transport, hold up and connect rigid “components” (siliceous spicules) to build the skeleton of demosponges (Nakayama et al. 2015, Kishimoto et al. 2019). This completely unexpected new paradigm of morphogenesis could be applicable even to vertebrates, since recent studies of fish fin formation revealed that cells produce needle-shaped collagen crystals, arrange them in parallel, and then connect them in fish fin formation (Kuroda et al. 2018, at Osaka Univ.). Thus, we are claiming that the mechanism by which cells manipulate non-cellular materials as workers and build the shape of an organism is an important morphogenetic mechanism of multicellular animals, and that there is a body-shaping of animals beyond embryogenesis which can only be understood by this concept. With the main purpose of presenting a new perspective on developmental biology, we are working to elucidate the cell behaviors and molecular mechanisms that carry out spiculose skeleton construction, and thus the mechanisms underlying the plastic growth and phenotypic plasticity of sponges through the development of our original analysis method.