title: Effects of organophosphate compounds on a soil protist, Colpoda inflata (Ciliophora, Colpodidae).
abstract: Many investigations on protists indicate that they play an important role in agricultural soils. We have tested the effects of three organophosphate (OP) pesticides, basudin, cidial, and fenix, on the soil ciliate Colpoda inflata, and examined its viability, fission rate, ability to excyst and extrude macronuclear chromatin into cytoplasm. Exposure to these OPs caused a dose-dependent effect on cell viability, and significantly reduced the mean fission rate at a concentration of 1/10(5) v/v. After exposure of resting cysts to 1/10(5) v/v or 1/10(6) v/v concentrations of basudin or cidial, the number of excysted cells was significantly lower than that of the controls. Conversely, exposure to a 1/10(5) v/v fenix concentration did not affect excystment and exposure to 1/10(6) v/v was found to promote excystment. Moreover, exposure to these OPs (1/10(4) v/v or 1/10(5) v/v) interferred with the ability to extrude macronuclear chromatin. The median lethal concentration in 60 min for each OPs tested was at least a hundred times lower than the doses recommended by the manufacturer. Finally, as the inhibition of cholinesterase (ChE) activity is the first target of OPs, the presence of ChE activity was checked in C. inflata. Three ChE activities were found, hydrolyzing the substrates acetyl-beta-methyl thiocholine iodide, propionyl thiocholine iodide and butyryl thiocholine iodide, that appeared to be very low and not inhibited by OP-exposure.
authors.affiliation: Department for the Study of the Territory and its Resources, University of Genoa, Corso Europa, 26, I-16132 Genova, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Trielli
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Chessa
authors.forename: Andrea
authors.initials: A
authors.lastname: Amaroli
authors.forename: Marzia
authors.initials: M
authors.lastname: Ognibene
authors.forename: Maria Umberta
authors.initials: MU
authors.lastname: Delmonte Corrado
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D002802:Cholinesterases / Q000378:metabolism; D016798:Ciliophora / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D009946:Organothiophosphorus Compounds / Q000494:pharmacology; D010575:Pesticides / Q000494:pharmacology*; D012988:Soil Microbiology
chemical_list: D002800:Cholinesterase Inhibitors; D009943:Organophosphorus Compounds; D009946:Organothiophosphorus Compounds; D010575:Pesticides; C518693:basudin; C518694:fenix; D002802:Cholinesterases; C008838:phenthoate