Evidence for regular sporulation by Haplosporidium nelsoni (MSX) (Ascetospora; Haplosporidiidae) in spat of the American oyster, Crassostrea virginica. |
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Authors: | R D Barber S A Kanaley S E Ford |
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Institution: | Shellfish Research Laboratory, Rutgers University, Cook College, Port Norris, New Jersey. |
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Abstract: | The spore stage of Haplosporidium nelsoni, the ascetosporan parasite causing multinucleated sphere unknown (MSX) disease in oysters, Crassostrea virginica, has been reported so rarely (less than 0.01% of infected oysters) that a second host has been postulated. However, recent intensive sampling of young (less than 1 year) oysters in Delaware Bay, U.S. suggests that spore formation occurs regularly in this group and that spores are produced in at least 75-85% of all infections reaching the advanced stage. Sporulation was seasonal, occurring over two to three weeks in late June/early July and again in late summer/early fall. Our data indicate that sporulation by H. nelsoni in oysters is more common than previously suspected, occurring in a segment of the host population that may not have been sufficiently sampled in the past, and that a direct life cycle should be reconsidered. |
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