Effect of the bioactive metabolite euplotin C on phagocytosis and fluid-phase endocytosis in the single-celled eukaryote Paramecium.
The effect of euplotin C -- a lipophilic bioactive metabolite produced by the ciliate Euplotes crassus -- on the kinetics of both phagocytosis of latex particles and fluid-phase uptake of dextran, was studied in the single-cell ciliate Paramecium primaurelia. The inhibition of food vacuole formation was concentration- and time-dependent (p<0.001), even if euplotin C did not completely block the phagocytosis. Following a 15 min treatment with a euplotin C (0.5 microg/ml), the latex particle uptake was inhibited up to 25%. Furthermore, the pretreatment of cells with taxol strongly counteracted euplotin C effect. The amount of extracellularly provided dextran, which is internalized exclusively by fluid-phase uptake, was quantified in cells whose phagocytic activity was blocked by trifluoperazine. The amount of the internalized dextran was about 50% of that in controls after 15 min incubation in the presence of euplotin C. Fluorescence confocal images showed that no endosomes were formed on the surface of these cells. The effect of euplotin C on the food vacuole formation and fluid-phase endocytosis is apparently mediated by a modification of microtubule network.
Ramoino
Paola
P
Dipartimento per lo Studio del Territorio e delle sue Risorse (DIP.TE.RIS.), Università di Genova, Corso Europa 26, I-16132, Genova, Italy. ramoino@dipteris.unige.it
Usai
Cesare
C
Maccione
Silvia
S
Beltrame
Francesco
F
Diaspro
Alberto
A
Fato
Marco
M
Guella
Graziano
G
Dini
Fernando
F
D000818:Animals; D000906:Antibodies / Q000032:analysis / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects*; D007840:Latex / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects; D017239:Paclitaxel / Q000494:pharmacology; D010247:Paramecium / Q000187:drug effects* / Q000502:physiology; D010587:Phagocytosis / Q000187:drug effects; D012717:Sesquiterpenes / Q000737:chemistry / Q000633:toxicity*; D013997:Time Factors; D014268:Trifluoperazine; D050257:Tubulin Modulators / Q000494:pharmacology; D014617:Vacuoles / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D000906:Antibodies; D003911:Dextrans; D007840:Latex; D012717:Sesquiterpenes; D050257:Tubulin Modulators; D014874:Water Pollutants, Chemical; C493253:euplotin C; D014268:Trifluoperazine; D017239:Paclitaxel