This degree of resolution is noteworthy since A. anophagefferens is so small and non-descript that normal microscopic identification and enumeration are highly uncertain at low cell concentrations. One obvious application of antibody probes would be in automated cell enumeration for field programs. As with other field applications, this has not yet been accomplished, however, but is under active investigation using solution and solid support-based formats. A useful instrument in this context is the flow cytometer, which uses a laser beam to excite individual cells in a flow stream, and characterizes their fluorescence and several other optical properties simultaneously. One current obstacle to flow cytometric analysis of immunolabeled cells is that the intensity of positive labeling is often not significantly higher than the background fluorescence of control or unlabeled cells.
Signal enhancement is clearly necessary, and several promising approaches are being explored.
Another problem is the loss of cells during the multiple steps involved in antibody labeling. Expectations are high that these problems can be overcome, but at this writing, automated applications of immunofluorescent techniques for harmful algae await further technique development. One of the problems that arises immediately when such work is initiated with HAB species is that little or no sequence information is available. Molecular studies of HAB species are still very much in their infancy. If the target gene or gene fragment has not been sequenced previously for the species, genus, or class of interest, it is necessary to establish the sequence database at the outset.