Coumarin based fluorescent dye for monitoring of siliceous structures in living organisms

Fluorescence dyes capable to specific interactions with definite substances are applied in biology for visualization of organelles and tracking of single molecules. The dyes which bear basic moieties are capable to stain acidic vesicles, including lysosomes and silica deposition vesicles in diatom algae. A new coumarin based fluorescent dye Q-N2 which contains amine fragment was synthesized. The new dye shows blue fluorescence which spectrum in water solutions does not depend on pH value but a green fluorescence appears when the dye is aggregated with siliceous surfaces or is entrapped into siliceous materials, e.g. valves of diatom algae. This effect allows to use Q-N2 dye for tracking silicification and biosilicification processes. Cultivation of diatom algae Ulnaria ferefusiformis (M.Kulikovskiy & H.Lange-Bertalot, 2016) in the presence of Q-N2 shows presence of condensed siliceous particles in the cell cytoplasm in several seconds after beginning of silicic acid consumption from the environment. This observation affords a basis to suppose formation of condensed siliceous structures (oligosilicates) during transportation of silicic acid through the cell membrane.