THE PAS ACCUMULATION BODIES IN PROROCENTRUM-LIMA AND PROROCENTRUM-MACULOSUM (DINOPHYCEAE) ARE DINOFLAGELLATE LYSOSOMES/

Numerous spherical bodies containing electron-dense material, fibrous material, and membranous material are present in the cytoplasm of two dinoflagellate species, Prorocentrum lima (Ehr.) Dodge and Prorocentru m maculosum Faust. Similar bodies have been observed in other dinoflag ellates and have been termed accumulation bodies or PAS bodies. In bot h Prorocentrum species, these bodies autofluoresce under blue light ex citation and increase in size with cell culture age. They possess acid phosphatase activity, react positively with the periodic acid/Schiff reagent, and stain with acridine orange. All these properties are char acteristic of eukaryotic lysosomes; thus, we propose that dinoflagella te accumulation bodies and PAS bodies are identical organelles and are , in fact, dinoflagellate lysosomes.