Fig. 3.

FITC-dextran labeled seawater demonstrating endocytosis. (A) Labeled threads (green) associated with the inward cytoplasmic stream and the formation of new vacuoles (v). The symbiotic algae (s) with their red autofluorescence are intracellular (in). (B) Seawater vacuoles in the last peripheral chamber after 25 min of incubation. The yellow color represents combined signal of red (algae) and green (FITC in SWV) fluorescence. (Inset): The average fluorescence intensity of five marked vacuoles along the arrow, note the gradual inward decrease of the fluorescence. v = vacuoles, in = intracellular, ex = extracellular, w = chamber wall, s = algae symbionts.