Immunochemical recognition of oligotrich ciliates

A protocol is presented for the application of immunochemical methods to the identification of planktonic ciliates, exemplified by the oligotrich Strombidium sp. Probes were produced in late 1989—early 1990 to Strombidium sp. in two forms: homogenates of (1) intact cells and (2) unassimilated Strombidium sp. antigens recovered from copepod fecal pellets. The antigen-antibody reaction was detected by dot blot assays using alkaline-phosphatase conjugated secondary antibodies as a reporter, and the reaction intensity was quantified by reflection densitometry. The immunogenic fraction of the antigen solutions was characterized by Western blots. Analysis of cross-reactions of anti-Strombidium sp. serum with 28 other species revealed a single strong cross-reaction, which was effectively eliminated by immunoadsorption. The antisera are suitable for detection of predation on ciliates in situ, free from the artifacts of laboratory incubations, and potentially for automated procedures for recognition of ciliates.