title: Assessment of the LuminoTox leachate phase assay as a complement to the LuminoTox solid phase assay: effect of fine particles in natural sediments.
abstract: The LuminoTox solid phase assay (Lum-SPA), developed to assess the potential ecotoxicity of natural polluted sediments, employs stabilized thylakoids isolated from spinach plant extracts. When thylakoids are exposed to polluted samples, the action of pollutants can interfere with transmission of chlorophyll fluorescence linked to Photosystems I and II, causing a decrease in fluorescence emission. To differentiate between bulk and leachate effects, we developed a complementary assay of the Lum-SPA named the LuminoTox leachate phase assay (Lum-LPA). Twelve natural sediments were selected on the basis of their potential ecotoxicity and different quantities of fines. Results showed that in the Lum-LPA, the IC50s were always lower than those observed in the Lum-SPA. Significant inverse correlations were found between the IC50s obtained with the Lum-SPA and the percentage of fines (silt+clay fraction). In order to identify the cause of the higher ecotoxicity found in the Lum-LPA, we tested the supernatant of the liquid phase recovered after centrifugation (3000 g), and it appeared far less toxic than the Lum-LPA filtrates. To confirm the hypothesis that sensitivity in the Lum-LPA could be due to the presence of very fine particles, Photosynthetic Enzyme Complexes (PECs) were exposed to two kinds of clay materials with and without copper (0.6 mg L(-1)). Similar results were obtained in the Lum-LPA for both cases, revealing the sensitivity of this test to very fine particles.
authors.affiliation: Université de Lorraine, Laboratoire des Interactions Ecotoxicologie, Biodiversité, Ecosystèmes, UMR 7146, Metz F-57070, France. karenburga@yahoo.com
authors.forename: Karen F
authors.initials: KF
authors.lastname: Burga Pérez
authors.forename: Rayna
authors.initials: R
authors.lastname: Charlatchka
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Férard
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D005453:Fluorescence; D019015:Geologic Sediments / Q000032:analysis*; D020128:Inhibitory Concentration 50; D010316:Particle Size; D012989:Soil Pollutants / Q000633:toxicity*; D018724:Spinacia oleracea / Q000187:drug effects* / Q000378:metabolism; D020524:Thylakoids / Q000187:drug effects* / Q000378:metabolism; D018675:Toxicity Tests / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D002734:Chlorophyll