title: The good, the bad, and the toxic: approaching hormesis in Daphnia magna exposed to an energetic compound.
abstract: A hormetic response is characterized by an opposite effect in small and large doses of chemical exposure, often resulting in seemingly beneficial effects at low doses. Here, we examined the potential mechanisms underlying the hormetic response of Daphnia magna to the energetic trinitrotoluene (TNT). Daphnia magna were exposed to TNT for 21 days, and a significant increase in adult length and number of neonates was identified at low concentrations (0.002-0.22 mg/L TNT), while toxic effects were identified at high concentrations (0.97 mg/L TNT and above). Microarray analysis of D. magna exposed to 0.004, 0.12, and 1.85 mg/L TNT identified effects on lipid metabolism as a potential mechanism underlying hormetic effects. Lipidomic analysis of exposed D. magna supported the hypothesis that TNT exposure affected lipid and fatty acid metabolism, showing that hormetic effects could be related to changes in polyunsaturated fatty acids known to be involved in Daphnia growth and reproduction. Our results show that Daphnia exposed to low levels of TNT presented hormetic growth and reproduction enhancement, while higher TNT concentrations had an opposite effect. Our results also show how a systems approach can help elucidate potential mechanisms of action and adverse outcomes.
authors.affiliation: U.S. Army Engineer Research and Development Center , Environmental Laboratory, 3909 Halls Ferry Road, Vicksburg, Mississippi 39180, USA.
authors.forename: Jacob K
authors.initials: JK
authors.lastname: Stanley
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Perkins
authors.forename: Tanwir
authors.initials: T
authors.lastname: Habib
authors.forename: Jerre G
authors.initials: JG
authors.lastname: Sims
authors.forename: Pornsawan
authors.initials: P
authors.lastname: Chappell
authors.forename: B Lynn
authors.initials: BL
authors.lastname: Escalon
authors.forename: Mitchell
authors.initials: M
authors.lastname: Wilbanks
authors.forename: Natàlia
authors.initials: N
authors.lastname: Garcia-Reyero
mesh_terms: D000818:Animals; D049628:Body Size / Q000187:drug effects; D003621:Daphnia / Q000187:drug effects*; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling; D059165:Hormesis; D050356:Lipid Metabolism / Q000187:drug effects; D012098:Reproduction / Q000187:drug effects; D059467:Transcriptome; D014303:Trinitrotoluene / Q000008:administration & dosage*
chemical_list: D014303:Trinitrotoluene
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