Application of a ciliate, Paramecium, as a sensor for a chemical substances

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Ciliate have characteristic cell functions, such as ciliary reversal, contraction of cell body, exocytosis and so on. These cell functions are induced by a contact of several stimuli such as chemical substances. It is known that these cell functions are controlled by intracellular calcium level.In this study, we investigate the relationship between the cell functions and intracellular calcium level in order to apply ciliates as a sensor for chemical substances.In response to the application of picric acid to the cell surface of a Paramecium caudatum cell, the Paramecium discharged trichocysts through the long term calcium transient (>3 s). In the case when ethanol was applied, the Paramecium discharged trichocysts. In this case, the calcium transient was short (<1 s). These results demonstrate that the intracellular calcium behavior is depending on the chemical stimuli.Next, we injected the fluorescent calcium indicator Calcium Green into a ciliate Didiniun nasutum and observed the intra-ciliary calcium level during spontaneous ciliary reversal of the cirri. In D. nasutum, calcium rose throughout the length of the cilia accompanied by ciliary reversal. These results strongly suggest that calcium influx sites for ciliary reversal are distributed throughout the cilium.