Symbioses between ascidians and the prokaryotic green alga Prochloron occur in various marine coastal habitats in the IndoPacific tropics. The endosymbiont is intermediate between oxygenic prokaryotes and green plant chloroplasts, and is evolutionarily unique. It has not been successfully cultured. This project will examine the acquisition of nitrogenous nutrients by the symbiosis and evaluate the exchanges of nitrogen between the host and symbiont. The Principal Investigators will also characterize the osmotic and compositional features of the cell sap of Prochloron to direct the development of suitable culture media. The study will promote new insights into the culture; add to our knowledge of the role of symbiotic systems in the nitrogen cycling of tropical coral.reef communities; elucidate the role of fluid dynamics on feeding in active suspension.feeders; and provide data relating to inorganic nitrogen uptake and utilization to the activities and levels of N.assimilation enzymes.
