Narrow-angle forward light scattering from individual algal cells: implications for size and shape discrimination in flow cytometry

摘要

Single-cell forward light scattering patterns have been examined for four algal species (one pennate diatom, two green flagellates and one filamentous cyanobacterium), mounted statically in a focused laser beam. In all cases, the distribution of light intensity at narrow angles (within the first scattering lobe) is well described by diffraction theory. Narrow-angle forward scattering measurements can therefore be used in principle to deduce the size and approximate shape of algal cells. The feasibility of using this technique in flow cytometry has been tested using an instrument which orientates elongated cells uniformly in the flow stream, and uses fibre optics to make azimuthally resolved forward scatter measurements at sub-degree polar angles. With this instrument it is possible to discriminate between species with similar volume and fluorescence characteristics using forward light scattering as a shape-sensitive parameter.