title: A DNA-based assay for toxic chemicals in wastewater.
abstract: Chemical toxicants, particularly metal ions, are a major contaminant in global waterways. Live-organism bioassays used to monitor chemical toxicants commonly involve measurements of activity or survival of a freshwater cladoceran (Ceriodaphnia dubia) or light emitted by the marine bacterium Vibrio fischeri, used in the commercial Microtox® bioassay. Here we describe a novel molecule-based assay system employing DNA as the chemical biosensor. Metals bind to DNA, causing structural changes that expel a bound (intercalated) fluorescent reporter dye. Analyses of test data using 48 wastewater samples potentially contaminated by metal ions show that the DNA-dye assay results correlate with those from C. dubia and Microtox bioassays. All three assays exhibit additive, antagonistic, and synergistic responses that cannot be predicted by knowing individual metal concentrations. Analyses of metals in these samples imply the presence of chemical toxicants other than metal ions. The DNA-dye assay is robust, has a 12-month shelf life, and is only slightly affected by sample pH in the range 4 to 9. The assay is completed in a matter of minutes, and its portability makes it well suited as a screening assay for use in the field. We conclude that the DNA-dye test is a surrogate bioassay suitable for screening chemical toxicity.
authors.affiliation: The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Foreman
authors.forename: Leo
authors.initials: L
authors.lastname: Phillips
authors.forename: Vangelis G
authors.initials: VG
authors.lastname: Kanellis
authors.forename: Daoud
authors.initials: D
authors.lastname: Hammoudeh
authors.forename: Christoph
authors.initials: C
authors.lastname: Naumann
authors.forename: Henri
authors.initials: H
authors.lastname: Wong
authors.forename: Robert
authors.initials: R
authors.lastname: Chisari
authors.forename: D Brynn
authors.initials: DB
authors.lastname: Hibbert
authors.forename: Garry S H
authors.initials: GS
authors.lastname: Lee
authors.forename: Ronald
authors.initials: R
authors.lastname: Patra
authors.forename: Moreno
authors.initials: M
authors.lastname: Julli
authors.forename: John
authors.initials: J
authors.lastname: Chapman
authors.forename: A Roger
authors.initials: AR
authors.lastname: Cooke
authors.forename: Cristobal G
authors.initials: CG
authors.lastname: dos Remedios
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001681:Biological Assay / Q000379:methods; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D003621:Daphnia / Q000187:drug effects / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry; D008670:Metals / Q000633:toxicity; D023382:Toxicity Tests, Acute / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical; D004247:DNA