Evolutionary origins of coordination: Physiological and molecular studies on sponges (Porifera)

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Sponges are members of the Porifera, the most primitive extant animals. Sponges are filter feeders and are the only group of multicellular animals without a nervous system, yet they have various types of slow behaviour that allow them to prevent clogging the filter. The first genome of a sponge is now available, and in it are many molecules that we see in nervous systems in other animals. My students and I study the sponge pre-nervous systems to understand how the first nervous systems might have evolved. We are interested in how sponges sense changes in their environment and how they coordinate whole body responses. This proposal will investigate a) the molecules involved in signaling between cells in the sponge, and the receptors available to receive signals on cells; b) the molecular mechanisms that sponges use to position sensory cells in the filtration system; and c) the physical parameters of fluid flow that guide the formation of the sponge body. Comparing genes found in sponges with those in animals that have nervous systems has highlighted remarkable similarities in the way signaling works in animals even without conventional nerves. Our proposed research program focuses on identifying the regions where signaling occurs between cells (is there a ‘proto-synapse’?) and ultimately determining where new cells involved in sensation and transmission of signals are produced in developing and in adult sponges.