[
Journal of Nematology,
1979]
Since it is sometimes difficult to distinguish between living and dead nematodes, dyes are used, such as New Blue R, Chrysoidin, Eosin-Y, and several fluorochromes, with varied success. A method is described here that is rapid (results in 15 min) and has a mechanism of staining that is understood. The technique was described first by Rotman and Papermaster, working with living mammalian cells, and later by Heslop-Harrison and Heslop-Harrison, working with plant material. It takes advantage of the presence of esterases which hydrolyse nonfluorescent fatty acid esters of fluorescein to yield fluorescein, which accumulates and is detectable by its fluorescence. Since esterases are known to be present in quantity in nematodes, concentrated principally in the nervous system, male spicules, and gut, this technique seemed worth testing as a rapid means of distinguishing between living and dead nematodes.