The effect of euplotin C-a cytotoxic secondary metabolite produced by the protist ciliate Euplotes crassus-on the voltage-dependent Ca(2+) channel activity was studied in a single-celled system by analyzing the swimming behavior of Paramecium. When the intraciliary Ca(2+) concentration associated with plasma membrane depolarization increases, a reversal in the direction of ciliary beating occurs, and consequently the swimming direction changes. The ciliary reversal duration is correlated with the amount of Ca(2+) influx. The present study demonstrates that the duration of continuous ciliary reversal (CCR), triggered by high external KCl concentrations, is longer in euplotin C-treated cells. Using selective Ca(2+) channel blockers, we demonstrate that euplotin C modulates Ca(2+) channels similar to the T-and L-types that occur in mammalian cells. Indeed, the increase of CCR duration significantly decreased when flunarizine and nimodipine-verapamil blockers were employed. Membrane fluidity measurements using a fluorescent dye, 6-lauroyl-2-dimethylaminonaphtalene (laurdan), indicated that membranes in euplotin C-treated cells are more tightly packed and ordered than membranes in control cells. Our data suggest that euplotin C enhances backward swimming in our unicellular model system by interacting with the ciliary Ca(2+) channel functions through the reduction of cell membrane fluidity.

Biophysical effects of the natural product euplotin C on the Paramecium membrane

RAMOINO, PAOLA;BIANCHINI, PAOLO;DIASPRO, ALBERTO GIOVANNI;USAI, CESARE
2009

Abstract

The effect of euplotin C-a cytotoxic secondary metabolite produced by the protist ciliate Euplotes crassus-on the voltage-dependent Ca(2+) channel activity was studied in a single-celled system by analyzing the swimming behavior of Paramecium. When the intraciliary Ca(2+) concentration associated with plasma membrane depolarization increases, a reversal in the direction of ciliary beating occurs, and consequently the swimming direction changes. The ciliary reversal duration is correlated with the amount of Ca(2+) influx. The present study demonstrates that the duration of continuous ciliary reversal (CCR), triggered by high external KCl concentrations, is longer in euplotin C-treated cells. Using selective Ca(2+) channel blockers, we demonstrate that euplotin C modulates Ca(2+) channels similar to the T-and L-types that occur in mammalian cells. Indeed, the increase of CCR duration significantly decreased when flunarizine and nimodipine-verapamil blockers were employed. Membrane fluidity measurements using a fluorescent dye, 6-lauroyl-2-dimethylaminonaphtalene (laurdan), indicated that membranes in euplotin C-treated cells are more tightly packed and ordered than membranes in control cells. Our data suggest that euplotin C enhances backward swimming in our unicellular model system by interacting with the ciliary Ca(2+) channel functions through the reduction of cell membrane fluidity.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/249532
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 3
  • ???jsp.display-item.citation.isi??? 2
social impact