title: Action mechanisms of the secondary metabolite euplotin C: signaling and functional role in Euplotes.
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 Ca(2+) 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.
authors.affiliation: Dipartimento per lo Studio del Territorio e delle sue Risorse, Università di Genova, 16132 Genova, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Trielli
authors.forename: Davide
authors.initials: D
authors.lastname: Cervia
authors.forename: Graziano
authors.initials: G
authors.lastname: Di Giuseppe
authors.forename: Chiara
authors.initials: C
authors.lastname: Ristori
authors.forename: Thomas
authors.initials: T
authors.lastname: Kruppel
authors.forename: Bruno
authors.initials: B
authors.lastname: Burlando
authors.forename: Graziano
authors.initials: G
authors.lastname: Guella
authors.forename: Aldo
authors.initials: A
authors.lastname: Viarengo
authors.forename: Paola
authors.initials: P
authors.lastname: Bagnoli
authors.forename: Maria Umberta
authors.initials: MU
authors.lastname: Delmonte Corrado
authors.forename: Fernando
authors.initials: F
authors.lastname: Dini
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D016812:Euplotes / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000187:drug effects; D008124:Locomotion / Q000187:drug effects; D008247:Lysosomes / Q000737:chemistry; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D015388:Organelles / Q000187:drug effects; D010587:Phagocytosis / Q000187:drug effects; D012717:Sesquiterpenes / Q000633:toxicity*; D012964:Sodium / Q000378:metabolism; D055672:Static Electricity
chemical_list: D012717:Sesquiterpenes; C493253:euplotin C; D012964:Sodium; D002118:Calcium