Action Mechanisms of the Secondary Metabolite Euplotin C: Signaling and Functional Role in Euplotes |
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Authors: | FRANCESCA TRIELLI DAVIDE CERVIA GRAZIANO DI GIUSEPPE CHIARA RISTORI THOMAS KRUPPEL BRUNO BURLANDO GRAZIANO GUELLA ALDO VIARENGO PAOLA BAGNOLI MARIA UMBERTA DELMONTE CORRADO FERNANDO DINI |
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Institution: | 1. Dipartimento per lo Studio del Territorio e delle sue Risorse, Università di Genova, 16132 Genova, Italy, and;2. Dipartimento di Scienze Ambientali, Università della Tuscia, 01100 Viterbo, Italy, and;3. Dipartimento di Biologia, Università di Pisa, 56126 Pisa, Italy, and;4. AG Zoophysiologie, FB Biologie/Chemie, Universit?t Osnabrück, 49069 Osnabrück, Germany, and;5. Dipartimento di Scienze dell'Ambiente e della Vita, Università del Piemonte Orientale, 15100 Alessandria, Italy, and;6. Dipartimento di Fisica, Laboratorio di Chimica Bioorganica, Università di Trento, and CNR, Institute of Biophysics, 38050 Trento, Italy |
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Abstract: | ABSTRACT. Among secondary metabolites, the acetylated hemiacetal sesquiterpene euplotin C has been isolated from the marine, ciliated protist Euplotes crassus, and provides an effective mechanism for reducing populations of potential competitors through its cytotoxic properties. However, intracellular signaling mechanisms and their functional correlates mediating the ecological role of euplotin C are largely unknown. We report here that, in E. vannus (an Euplotes morphospecies that does not produce euplotin C and shares with E. crasssus the same interstitial habitat), euplotin C rapidly increases the intracellular concentration of both Ca2+ and Na+, suggesting a generalized effect of this metabolite on cation transport systems. In addition, euplotin C does not induce oxidative stress, but modulates the electrical properties of E. vannus through an increase of the amplitude of graded action potentials. These events parallel the disassembling of the ciliary structures, the inhibition of cell motility, the occurrence of aberrant cytoplasmic vacuoles, and the rapid inhibition of phagocytic activity. Euplotin C also increases lysosomal pH and decreases lysosomal membrane stability of E. vannus. These results suggest that euplotin C exerts a marked disruption of those homeostatic mechanisms whose efficiency represents the essential prerequisite to face the challenges of the interstitial environment. |
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Keywords: | Action potentials cation homeostasis ciliated protists lysosomes marine microorganisms oxidative stress phagocytosis sesquiterpenoids |
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