title: Flow cytometric analysis to evaluate physiological alterations in herbicide-exposed Chlamydomonas moewusii cells.
abstract: Investigation of herbicide toxicology in non-target aquatic primary producers such as microalgae is of great importance from an ecological point of view. In order to study the toxicity of the widely used herbicide paraquat on freshwater green microalga Chlamydomonas moewusii, physiological changes associated with 96 h-exposures to this pollutant were monitored using flow cytometry (FCM) technique. Intracellular reactive oxygen species concentration, cytoplasmic membrane potential, metabolic activity and cell protein content were monitored to evaluate the toxicological impact of paraquat on algal physiology. Results showed that herbicide paraquat induced oxidative stress in C. moewusii cells, as it indicated the increase of both superoxide anion and hydrogen peroxide levels observed in non-chlorotic cells of cultures exposed to increasing herbicide concentrations. Furthermore, a progressive increase in the percentage of depolarised cells and a decrease in the metabolic activity level were observed in response to paraquat when non-chlorotic cells were analysed. Chlorotic cells were probably non-viable cells, based on the cytoplasmic membrane depolarisation, its metabolically non-active state and its drastically reduced protein content. In view of the obtained results, we have concluded that a range of significant physiological alterations, detected by flow cytometry, occur when C. moewusii, an ubiquitous microalga in freshwater environments, is challenged with environmentally relevant concentrations of the herbicide paraquat.
authors.affiliation: Laboratorio de Microbiología, Facultad de Ciencias, Universidad de A Coruña, Coruña, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Prado
authors.forename: Carmen
authors.initials: C
authors.lastname: Rioboo
authors.forename: Concepción
authors.initials: C
authors.lastname: Herrero
authors.forename: Paula
authors.initials: P
authors.lastname: Suárez-Bregua
authors.forename: Angeles
authors.initials: A
authors.lastname: Cid
mesh_terms: D002462:Cell Membrane / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002696:Chlamydomonas / Q000187:drug effects* / Q000378:metabolism; D004784:Environmental Monitoring; D005434:Flow Cytometry / Q000379:methods*; D006540:Herbicides / Q000633:toxicity*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008564:Membrane Potentials; D018384:Oxidative Stress / Q000187:drug effects; D010269:Paraquat / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D006540:Herbicides; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D013481:Superoxides; D006861:Hydrogen Peroxide; D010269:Paraquat