title: Ultrastructural alterations in ciliated protozoa under heavy metal exposure.
abstract: Transmission electron microscopy was used to study the ultrastructural changes induced by exposure to Cd or Zn in three species of ciliated protozoa: Colpoda steinii, Cyrtolophosis elongata and Drepanomonas revoluta. The main cytoplasmic alterations were partial mitochondrial degeneration, cytoplasmic vacuolisation, accumulation of membranous debris and autophagosome formation. At the nuclear level we detected nucleolar fusion in the macronucleus, and micronuclear membrane modifications. We compared these modifications with those coinciding with ciliate encystment (a differentiation process induced by environmental nutritional stress) and with changes in eukaryotic cells treated with staurosporine, a potent protein kinase inhibitor considered to be an apoptosis inducer. Exposure to heavy metals also coincided with the appearance of electron-dense accumulations in the cytoplasm, which might be related to metallothionein-mediated detoxification. The results are compared with previously reported data from ciliates and microalgae treated with heavy metals.
authors.affiliation: Departamento de Microbiología III, Facultad de Biología, Universidad Complutense (UCM), C/. José Antonio Novais 2, 28040 Madrid, Spain. anamarti@bio.ucm.es
authors.forename: Ana
authors.initials: A
authors.lastname: Martín-González
authors.forename: Sara
authors.initials: S
authors.lastname: Borniquel
authors.forename: Silvia
authors.initials: S
authors.lastname: Díaz
authors.forename: Ruth
authors.initials: R
authors.lastname: Ortega
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Gutiérrez
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D016798:Ciliophora / Q000187:drug effects* / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D015032:Zinc / Q000633:toxicity*
chemical_list: D002104:Cadmium; D015032:Zinc