X-RAY-MICROANALYSIS IN CRYOSECTIONS OF NATIVELY FROZEN PARAMECIUM-CAUDATUM WITH REGARD TO ION DISTRIBUTION IN CILIATES

Abstract

Cells of P. caudatum were shock-frozen without pretreatment for cryoultramicrotomy and freeze-dried for subsequent X-ray microanalysis. Na, Mg, P, S, Cl, K and Ca were detected in different amounts in several subcellular compartments. In particular, Ca was localized below the cell surface (pellicle). Trichocysts contained significant amounts of Na in their base but not in the tip. Na, Mg, P, S, Cl, K and Ca were found in electron dense deposits within the lumen of the contractile vacuole. A small K concentration was found in the cytoplasm and in the mitochondria. X-ray microanalysis of the element distribution in different subcellular compartments provides information for the understanding of cellular functions such as exocytosis, locomotion and ion regulation.