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University of Iowa News Release


Feb. 8, 2011

UI biologist describes genome of 'canary in coal mine' for freshwater ecology

Genes that may appear, at first glance, to be duplicates can be essential to the nature of an organism.

That is the message of a paper published in the Feb. 4 issue of the journal Science by John Manak, assistant professor of biology in the University of Iowa College of Liberal Arts and Sciences, and colleagues. They describe the draft genome of an organism that serves as a kind of "canary in the coal mine" for the ecology of freshwater streams and ponds.

The water flea, also known as Daphnia pulex, is important to freshwater ecosystems as a principal grazer of algae, a primary food source for fish and a sentinel of healthy still-water, inland ecosystems.

The tiny crustacean shows a range of development, such as switching between clonal and sexual reproduction, in response to varying environmental conditions. Also, some species change migration behavior and develop exaggerated morphological defenses in response to predators.

The researchers found that the water flea's genome contains at least 30,907 genes -- a very high number -- with more than a third having no counterparts in any similar organism and with the most amplified gene groups being specific to the Daphnia lineage.

The finding suggests that the maintenance of duplicate genes is not random. The analysis of gene expression under different environmental conditions reveals that numerous gene groups acquire divergent expression patterns soon after duplication.

In summary, it's the genes specific to Daphnia that show the greatest response to ecological challenges, according to Manak, also a researcher in the Roy J. Carver Center for Genomics.

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