Ref ID : 4153
Arno Tiedtke; Selection for and Enrichment of Non-Discharge Mucocyst Variants of Tetrahymena thermophila. J.Protozool. 32(2):317-320, 1985
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The present protocol for selection for and enrichment of potential non-discharge mucocyst variants of Tetrahymena thermophila is based on the ability of wild-type cells to discharge their mucocyst contents simultaneously when stimulated with alcian blue 8 GS. Under appropriate ionic conditions, the discharged mucocyst contents form a capsule around each cell and prevent its locomotion. Non-discharge variants unable to shed a capsule are assumed to retain their ability to swim and are simulated in this study by cells not induced to shed their capsule. For mass phenotype screening, the conditions for maximum capsule shedding were established for wild-type cells. One hour starvation in Wagner's solution rendered 100% of the cells competent to shed a capsule when triggered with a 0.4% solution of alcian blue 8 GS. Decontamination of the shedding mixture by addition of egg albumin in a final concentration of 0.1% guaranteed survival of >95% of these cells that were now encapsulated, but allowed up to 5% of the cells to escape their capsule and swim freely. Cells with intact mucocysts and cells with emptied mucocysts were separated in reconstruction experiments by density-gradient centrifugation in which 95% of the cells with intact mucocysts appeared in a discrete band. Using the same protocol, the efficiency of separation was tested with mixtures of morphologically marked (food vacuoles stained with India ink) and genetically marked (resistance to cycloheximide) cells. Using 1:1 mixtures of marked cells with intact mucocysts and cells with emptied mucocysts (or vice versa), the cells with intact mucocysts were efficiently separated from other cells; one cell with emptied mucocysts per 100 cells with intact mucocysts was found in the upper discrete gradient band.