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Release: Aug. 28, 2002

Biologist Conducts Research On Origins Of 'Red Tide'

A University of Iowa researcher is studying a phenomenon that may help scientists to better understand the cause of the ecologically and financially costly "red tide" that periodically kills millions of fish along the U.S. Atlantic and Gulf coasts.

Debashish Bhattacharya, assistant professor of biological sciences in the University of Iowa College of Liberal Arts and Sciences, whose work is published in the Aug. 9 issue of the journal Proceedings of the National Academy of Sciences, says his goal is to explain the origin of the cell component called a "plastid," responsible for photosynthesis in marine algae.

"The dinoflagellates, or marine plankton, are one of the most economically important single-celled organisms because of the toxic red tides that they cause resulting in fish and shellfish mortality. Our work lays the foundation for understanding the basic biology of these species," he says.

Red tide is a natural phenomenon that results from massive blooms of tiny, single-celled algae called Karenia brevis, usually found in warm salt water.

Bhattacharya notes that algae, as primary producers in the food chain, are critical to maintaining life on Earth, and the plastid, in turn, is the cell organelle responsible for algae photosynthesis. As a result, the question of plastid origin is an important problem in evolutionary biology, Bhattacharya's primary field of research.

"We show in this paper that the dinoflagellate plastid originates from a so-called tertiary endosymbiosis in which the dinoflagellate 'host' cell has stolen its photosynthetic ability from another algal group, the haptophytes," he says. "My lab is interested in how endosymbiosis has driven the origin and diversification of the huge diversity of photosynthetic eukaryotes (single-celled organisms) on our planet. We believe that endosymbiosis is one of the most important evolutionary forces in the history of the Earth."

Bhattacharya says that his laboratory has the best phylogenetic resources to unravel the evolutionary history of these algae. He adds that his group recently was awarded a $790,000 grant from the National Science Foundation and the U.S. Department of Agriculture to generate a genomic database for the toxic dinoflagelate Alexandrium tamarense. He says the database will be valuable to a large number of scientists working on the evolution and basic biology of various algae.