Meeting Abstract
Aquaporins are channel proteins that transport water and, sometimes, small solutes across membranes. Aquaporins have been shown to increase the movement of water by 10-fold the rate of passive diffusion, and are involved in important functions like cell volume regulation and maintenance of osmotic homeostasis. Despite the importance of aquaporins, little is known about the evolutionary history of aquaporins in animals, especially early diverging taxa that are all marine. Here we report on the phylogenetic diversity and relationship of aquaporins from four representative species, Mnemiopsis leidyi (Ctenophora), Amphimedon queenslandica (Porifera), Trichoplax adherens (Placozoa) and Nematostella vectensis (Cnidaria), with metazoan and single cell outgroups. We utilized heterologous expression assays to determine how phylogenetic identity relates to structure and function in these membrane proteins. Aquaporins from Mnemiopsis, Amphimedon, Trichoplax and Nematostella were cloned, expressed in Xenopus oocytes, and assayed for transport function of water, urea and glycerol. Aquaporins were predicted to have functions reflective of their phylogenetic relationship to related membrane proteins in bilatarian species whose structure and functions are known. Comparisons of protein sequence, phylogenetic relationship and function provide insight into the early evolution of these critical proteins.
