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.

Photocatalytic degradation kinetics and mechanisms of fungicide tebuconazole in aqueous TiO2 suspensions

“…Hormesis is a dose-response phenomenon and describes a stimulating effect of sub-inhibitory concentrations of toxic substances in organisms [23]. A hormetic response is characterized by an opposite effect at high and low doses of chemical exposure, often resulting in beneficial effects at low quantities [23].…”

“…Hormesis is a dose-response phenomenon and describes a stimulating effect of sub-inhibitory concentrations of toxic substances in organisms [23]. A hormetic response is characterized by an opposite effect at high and low doses of chemical exposure, often resulting in beneficial effects at low quantities [23]. Hormetic growth stimulation has frequently been observed in different biological systems (animals, plants, and microorganisms) exposed to low concentrations of a great variety of chemical compounds such as heavy metals, pesticides, organic arsenic compounds and antibiotics [24].…”

Blocking the entrance of AMP pocket results in hormetic stimulation of imidazolium-based ionic liquids to firefly luciferase

“…Calabrese (2010) asserted that hormesis is a generalized phenomenon rather than an exceptional case. Numerous studies have revealed that many chemicals such as bisphenol A, energetic trinitrotoluene, pesticide and antibiotic to cell, bacteria or plant display the non-monotonic concentration response (Bouskine et al, 2009;Belz et al, 2011;Pupo et al, 2012;Gressel and Dodds, 2013;Sheng et al, 2013;Stanley et al, 2013;Vandenberg et al, 2013). In our previous work, we also found the HCRs of some organic solvents, ionic liquids and inorganic salts to Vibrio qinghaiensis sp.-Q67 and firefly luciferase Zhang et al, 2013a,b).…”

Endocrinology: Advances through omics and related technologies

“…This organism currently lacks genomic/genetic and molecular tools necessary for advanced research. A recent study by (Stanley et al, 2013) used an integrative approach that included transcriptomics, lipidomics, and apical endpoints to link effects on lipid metabolism to hormetic effects (increased growth and reproduction) on D. magna. Similar findings and effects have been seen in other species including fathead Table 1 Invertebrate species used as alternative for models or disorders in vertebrates.…”