Interactions of species in an Anabaena flos-aquae association from the Plußsee (East-Holstein, Federal Republic of Germany).

Fluorescent probes have been applied to study by epifluorescence microscopy interactions between species in an Anabaena flos-aquae association, derived from a freshwater community. Glycoconjugates (macromolecules containing carbohydrate residues) have been shown to play a vital role in recognition processes and in formation of attachment sites between cells. By use of a group of proteins (lectins) with specific affinities to certain sugar residues we were able to clucidate specific patterns expressed at cellular surfaces, thereby indicating the physiological state of a cell. Low molecular weight fluorochromes, like the fluorescent brightener calcofluor white have been shown to be extremely useful tools for visualizing structural entities (and species) which otherwise escape notice by microscopy. We have demonstrated that the decline of the bloom of Anabaena flos-aquae was caused or at least accelerated by action of a fungus (chytrid). We also proved that the shell (lorica) of a choanoflagellate most likely is built from chitin.