Parasite-infected dragonflies suffer the same metabolic disorders that have led to an epidemic of obesity and type-2 diabetes in humans, reveal the findings of research conducted at Penn State University that are due to be published in the 5 December 2006 issue of the Proceedings of the National Academy of Science and also in the PNAS early online edition at www.pnas.org on 21 November. The discovery expands the known taxonomic breadth of metabolic disease and suggests that the study of microbes found in human intestines may provide a greater understanding of the root causes of human metabolic dysfunction.

James Marden, professor of biology and an insect physiologist at Penn State, and Ruud Schilder, who in August 2006 earned his doctorate in biology at Penn State and is now a postdoctoral fellow at the University of Nebraska, are the first to show a non-mammalian species suffering from metabolic dysfunction in ways similar to humans. "Metabolic disease isn't some strange thing having just to do with humans," said Marden. "Animals in general suffer from these symptoms."

The work is also novel because it links metabolic disease to a supposedly harmless parasite living in the dragonfly's gut. The parasites, known as gregarines, belong to the Apicomplexa, a group of microorganisms that includes protozoa, which cause diseases like malaria and cryptosporidiosis. The dragonfly species that Marden and Schilder studied is Libellula pulchella. The microbes disrupting the dragonfly metabolism may hold clues for scientists looking for the root causes of metabolic diseases in humans, according to Marden and Schilder's paper

"All of these symptoms, and the underlying processes behind these symptoms that we're seeing in these dragonflies, are pretty much identical to what you see in mammalian metabolic syndrome and obesity," said Marden. "We're seeing it all relate back to this non-invasive protozoan in the
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Contact: Barbara K. Kennedy
science@psu.edu
814-863-4682
Penn State
20-Nov-2006