This award will support a two-year collaborative project between Professor Martin H. Spalding, Department of Botany, Iowa State University, and Dr. Murray R. Badger, Australian National University, Canberra, under the U.S.-Australia Cooperative Science Program. The scientists will study aspects of the photosynthetic process in the unicellular alga Chlamydomonas reinhardtii. This and other unicellular algae are very efficient in their use of external inorganic carbon for photosynthesis, and exhibit additional interesting photosynthetic characteristics as well. The cooperating researchers believe these effects are the result of intracellular carbon dioxide concentration levels in the algae which are significantly greater than in most higher plants. A "carbon dioxide-concentrating mechanism" has been proposed by the investigators which involves energy-requiring transport of inorganic carbon (as carbon dioxide or bicarbonate ion) into and within the algal cells, followed by enzyme-catalyzed conversion of accumulated bicarbonate ion to yield enhanced levels of carbon dioxide. It is the aim of this cooperative project to understand better the transport mechanism and to determine the location of the enzyme (carbonic anhydrase) within the cell. Both the U.S. and Australian groups have been active in this area of research, using complementary approaches and techniques. Professor Spalding and his colleagues have emphasized molecular genetic studies of the CO2-concentrating mechanism in microalgae, while Dr. Badger and his group in Australia have focused their related efforts on cyanobacteria, and have developed special mass spectrometric and centrifugation techniques to aid in the analyses. The cooperative project will build upon the strengths of both groups, and will involve exchanges by the principal investigators as well as by their postdoctoral associates.
