DETECTION OF THE ICHTHYOTOXIC DINOFLAGELLATE GYRODINIUM (CF) AUREOLUMAND MORPHOLOGICALLY RELATED GYMNODINIUM SPECIES USING MONOCLONAL-ANTIBODIES - A SPECIFIC IMMUNOLOGICAL TOOL

Sixteen monoclonal antibodies which recognize different cell surface a ntigens of the ichthyotoxic marine dinoflagellate Gyrodinium cf. aureo lum were prepared and characterized for use in identification by both immunofluorescence microscopy and flow cytometry. Based on the labelin g results obtained from indirect immunofluorescence assays the monoclo nals could be divided into 3 groups: (I) fluorescence of the overall c ell surface, (II) fluorescence of the overall cell surface together wi th the flagella, and (III) fluorescence of granular-like structures ra ndomly distributed along the cell surface and at the edges of the sulc us and cingulum. Cross-reactivity of 6 selected monoclonals with other phytoplankton species revealed that labeling was restricted to G. aur eolum/G. cf. aureolum and to the morphologically closely related speci es Gymnodinium nagasakiense and G. mikimotoi. This suggests a taxonomi c proximity of these species. Fixation of samples with paraformaldehyd e produced the optimal immunochemical response, resulting in the stron gest fluorescence intensities. In flow cytometric analyses, labeled ce lls of G. cf. aureolum could be distinguished sufficiently from unlabe led controls when monoclonals of Group II and a pooled serum (combined antibodies of Groups I, II, and III) were used. This immunochemical t echnique will be applied in an early warning system to detect G. aureo lum cells at dilute concentrations using flow cytometry or, alternativ ely, image analysis.