Lipid Metabolism in the Oyster Protozoan Parasite, Perkinsus Marinus

College Of William & Mary Virginia Institute Of Marine Science, Gloucester Point VA

Investigators

Abstract

Diseases caused by parasitic species of the genus, Perkinsus, in bivalve mollusks are a worldwide problem. The parasite, Perkinsus marinus (Dermo) has been one of the two most important protozoan parasites causing severe mortality in the American oyster, Crassostrea virginica, on the east and Gulf coasts since the 1950s. Although this parasite's host is an ecologically and economically important aquatic species, previously no information existed on its lipid metabolism and biosynthesis. A previous NSF award, revealed important information concerning lipid metabolism in P. marinus in relation to its host. Some of the important findings are that this parasite has a capability for phospholipid synthesis similar to the Plasmodium spp. that cause malarial disease and as most other parasitic protozoans, can acquire and metabolize exogenous lipids. However, unlike other parasitic protozoans, which rely on their host for essential lipids, P. marinus is able to synthesize a range of saturated and unsaturated fatty acids, including the essential fatty acid, arachidonic acid. No other parasitic protozoans have been reported to have such a capability. Interestingly, this parasite appears to have different metabolic phases depending upon whether or not it is associated with its host or not. To further elucidate the lipid metabolism in this parasite and its relation to the parasite's development, life cycle completion, disease transmission, and virulence and pathogenesis of the host, the present project employs advanced analytical technology and molecular and genomic approaches to test the key hypotheses built on the previous findings. The study addresses not only basic lipid metabolism questions with potential application to disease control for oyster acquaculture production, but to diseases caused by other Perkinsus spp. in other bivalve species such as clams. An in-depth understanding of the significance of de novo lipid and fatty acid synthesis in P. marinus may lead to the development of parasiticidal drugs to control this parasite and other parasitic protozoans, including those species affecting humans. Lipid biosynthetic pathways are currently being investigated as potential drug targets in several protozoan parasites of humans including Plasmodium and Trypanosoma species. Importantly, this project will provide opportunities to post-graduate, graduate, undergraduate, and high school students to receive hands-on research experience and training in marine science in general and lipid biochemistry, molecular genetics, and parasitology in particular.