Discrimination of the Cell Surface of the Coccolithophorid Pleurochrysis haptonemofera from Light Scattering and Fluorescence After Fluorescein-Isothiocyanate-Labeled Lectin Staining Measured by Flow Cytometry

We investigated the extent of calcification on the cell surface of the coccolithophorid Pleurochrysis haptonemofera using flow cytometry. Side scattering (SSC) by coccolith-bearing cells was higher than that by naked cells, suggesting the difference was due to scattering of the laser beam by the coccoliths. SSC of coccolith-bearing cells under acidic conditions corresponded well to the extracellular Ca content, although SSC could not be used to detect a delicate change in the coccolith thickness. The increase in SSC during the reproduction of coccoliths after decalcification was consistent with the increase in the number of coccoliths on the cell surface. The fluorescence after fluorescein-isothiocyanate-labeled lectin staining suggests that α-d-mannose, α-d-glucose, d-galactose, d-N-acetylgalactosamine, or derivatives of them are included in the coccoliths. Measurement of SSC and fluorescence after fluorescein-isothiocyanate-labeled lectin staining enabled rapid and quantitative determination of the status on the cell surface and isolation of desirable cells for physiological studies by cell sorting. Received May 22, 2001; accepted July 30, 2001.