High yield isolation procedure for intact secretory organelles (trichocysts) from different Paramecium tetraurelia strains.
The secretory organelles (trichocysts) of Paramecium tetraurelia, wild type (7S) and some mutant cells (non-discharge strains, nd), were isolated with their intact membranes using a self-generating Percoll gradient. This has become possible by detaching trichocysts before (nd) or during (7S) homogenization from the cell membrane, where they are normally firmly attached. Membrane integrity was tested in several ways (acridine orange trapping, Ca2+ insensitivity). Measurement of several marker enzymes, DNA and tubulin content showed considerable enrichment of trichocysts over other subcellular constituents. Calculation of the yield showed that more than 50% of the whole amount of trichocysts per cell can be isolated. However, with the method described trichocysts can be isolated in an intact state from a variety of Paramecium tetraurelia strains so that they now have become amenable to further analyses.