Scientists capture, identify parasitic killer of Pacific oysters

Researchers say they've captured a tiny, elusive parasite plaguing oysters from British Columbia to California, and making the delicacy unappealing to humans. University of British Columbia researchers say they've managed to isolate the Microcytos mackini, a parasite that infects mainly Pacific oysters, leading to unsightly green lesions and then death. "M. mackini has eluded capture for more than 50 years because it lives inside the oyster's cells and has proved impossible to grow and study in a lab," UBC researcher Patrick Keeling said. Writing in the journal Current Biology, the research team from UBC and Canada's Department of Fisheries and Oceans report they have isolated the parasites from infected oysters and analyzed their genes. "We figured out where M. mackini came from in the evolutionary tree of life -- it is part of an enigmatic group of amoebae called Rhizaria that was only itself discovered a few years ago," Keeling said. "These parasites have an extremely reduced metabolism. They can't survive in oxygen and its mitochondria -- or cellular powerhouse -- can't produce energy, so they probably steals most things from the oyster host in order to survive," he said. While not considered a health threat to humans, the parasite disease makes the oysters unappealing for human consumption and have had a negative impact on British Columbia oyster production, an industry said to be worth $9.2 million in 2011.