title: Validation of photosynthetic-fluorescence parameters as biomarkers for isoproturon toxic effect on alga Scenedesmus obliquus.
abstract: Photosynthetic-fluorescence parameters were investigated to be used as valid biomarkers of toxicity when alga Scenedesmus obliquus was exposed to isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] effect. Chlorophyll fluorescence induction of algal cells treated with isoproturon showed inactivation of photosystem II (PSII) reaction centers and strong inhibition of PSII electron transport. A linear correlation was found (R2>or=0.861) between the change of cells density affected by isoproturon and the change of effective PSII quantum yield (PhiM'), photochemical quenching (qP) and relative photochemical quenching (qP(rel)) values. The cells density was also linearly dependent (R2=0.838) on the relative unquenched fluorescence parameter (UQF(rel)). Non-linear correlation was found (R2=0.937) only between cells density and the energy transfer efficiency from absorbed light to PSII reaction center (ABS/RC). The order of sensitivity determined by the EC-50% was: UQF(rel)>PhiM'>qP>qP(rel)>ABS/RC. Correlations between cells density and those photosynthetic-fluorescence parameters provide supporting evidence to use them as biomarkers of toxicity for environmental pollutants.
authors.affiliation: University of Quebec in Montreal, Department of Chemistry, Environmental Toxicology Research Center--TOXEN, 2101, Jeanne-Mance, Montreal, Quebec H2X 2J6, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Dewez
authors.forename: Olivier
authors.initials: O
authors.lastname: Didur
authors.forename: Jonathan
authors.initials: J
authors.lastname: Vincent-Héroux
authors.forename: Radovan
authors.initials: R
authors.lastname: Popovic
mesh_terms: D002734:Chlorophyll; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D005453:Fluorescence; D006540:Herbicides / Q000633:toxicity*; D016014:Linear Models; D010671:Phenylurea Compounds / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000187:drug effects; D044444:Scenedesmus / Q000187:drug effects / Q000378:metabolism*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D006540:Herbicides; D010671:Phenylurea Compounds; D045332:Photosystem II Protein Complex; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; C028904:isoproturon