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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7341

Evelyn Plumper, Manfred Freiburg, and Klaus Heckmann; Inhibition of Pair Formation by Concanavalin A and Concanavalin A-Binding Glycoconjugates in Euplotes octocarinatus. J.Eukaryot.Microbiol. 42(2):166-173, 1995

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Concanavalin A (>/_50 µg/ml) inhibits pair formation in both of the two complementary mating types of Euplotes octocarinatus studied in this investigation. This effect can be reversed by methyl-alpha-D-mannose. Concanavalin A is accessilbe for methyl-alpha-D-mannose until pairs are formed. Methyl-alpha-D-mannose as well as methyl-alpha-D-glucose and 2-acetamido-2-deoxy-D-glucose alone do not inhibit pair formation unless applied in concentrations >/_60 mM. The Concanavalin A-sensitive phase of preconjugant interaction starts 2 hr after cells are induced to conjugate. Based on these observations we suggest that Concanavalin A might exhibit its action by binding to carbohydrate moieties of preconjugation-specific adhesion molecules and thereby might allosterically block interactions with their counterparts. To identify preconjugation-specific alterations in number of localization of Concanavalin A-binding glycoconjugates, we probed western blots of total cell proteins or fixed cells, respecively, with digoxigenin-labeled Concanavalin A. On Concanabalin A blots 20 different Concanavalin A-binding glycoconjugates were identified in mating-competent cells. Localization of Concanavalin A-binding sites on mating-competent cells by light microscopy resulted in predominant labeling of a comma-shaped structure near the paroral membranelle. During the preconjugation period no changes in number or localization of Con A-binding glycoconjugates were detected. Possible reasons are discussed.