The rapid analysis of single marine cells by flow cytometry

Abstract

Analytical flow cytometry (AFC) is a novel technique for the rapid (more than 103 s-1) analysis and sorting of single cells based upon simultaneous, multiple measurements of laser-induced particle fluorescence, light scatter and impedance. Originally developed for biomedical use, AFC is now being adapted to analyse single-celled organisms such as phytoplankton and bacteria which are present as trace but functionally important components in seawater. Marine AFC has been used to analytically differentiate and sort these organisms from the heterogeneous assemblage of particles present in seawater. Chlorophyll autofluorescence is an unique biomarker for photosynthetic organisms and has been used to analyse phytoplankton cytometrically both in the laboratory and at sea. A theoretical and practical framework for the cytometric quantitation of cellular chlorophyll in phytoplankton based on autofluorescence is presented. Other subcellular constituents such as enzymes, lipids, nucleic acids and toxins in phytoplankton have recently been analysed by AFC using immuno-, induced or applied fluorescent labelling techniques. Examples are presented together with novel developments in fringe areas of cytometry that are likely to influence AFC of single marine cells in the near future.