OBSERVATIONS OF THE SYMBIONT-BEARING FORAMINIFER AMPHISTEGINA GIBBOSA UTILIZING CELLTRACKER GREEN AND EPIFLUORESCENT MICROSCOPY

The use of fluorescent microscopy and fluorescent probes, such as the metabolically activated probe CellTracker Green CMFDA (CTG) or the calcite marker Calcein, has become more common in work involving living Foraminifera. CTG is especially useful in determining the vitality of foraminifers collected in situ due to the requirement of metabolic activity in producing fluorescence. This metabolic requirement, as well as the relatively quick production of the fluorescent reaction products, makes CTG a prime candidate for determining mortality in laboratory experiments. Work with the symbiont-bearing foraminifer Amphistegina gibbosa has shown that the species is capable of surviving both acute chemical exposure and extended periods of total darkness by entering a low-activity dormant state. The use of CTG and fluorescent microscopy may help speed the determination of mortality in such experiments, but is complicated by the autofluorescence of the diatom symbionts. Here we present methods adapting fluorescence microscopy for use with symbiont-bearing foraminifera, as well as observations on CTG fluorescence and autofluorescence in A. gibbosa following both chemical exposure and periods of total darkness.