Browsing by Author "Matson, Cole W"

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    Development of the morpholino gene knockdown technique in Fundulus heteroclitus: a tool for studying molecular mechanisms in an established environmental model.
    (Aquat Toxicol, 2008-05-30) Matson, Cole W; Clark, Bryan W; Jenny, Matthew J; Fleming, Carrie R; Hahn, Mark E; Di Giulio, Richard T
    A significant challenge in environmental toxicology is that many genetic and genomic tools available in laboratory models are not developed for commonly used environmental models. The Atlantic killifish (Fundulus heteroclitus) is one of the most studied teleost environmental models, yet few genetic or genomic tools have been developed for use in this species. The advancement of genetic and evolutionary toxicology will require that many of the tools developed in laboratory models be transferred into species more applicable to environmental toxicology. Antisense morpholino oligonucleotide (MO) gene knockdown technology has been widely utilized to study development in zebrafish and has been proven to be a powerful tool in toxicological investigations through direct manipulation of molecular pathways. To expand the utility of killifish as an environmental model, MO gene knockdown technology was adapted for use in Fundulus. Morpholino microinjection methods were altered to overcome the significant differences between these two species. Morpholino efficacy and functional duration were evaluated with molecular and phenotypic methods. A cytochrome P450-1A (CYP1A) MO was used to confirm effectiveness of the methodology. For CYP1A MO-injected embryos, a 70% reduction in CYP1A activity, a 86% reduction in total CYP1A protein, a significant increase in beta-naphthoflavone-induced teratogenicity, and estimates of functional duration (50% reduction in activity 10 dpf, and 86% reduction in total protein 12 dpf) conclusively demonstrated that MO technologies can be used effectively in killifish and will likely be just as informative as they have been in zebrafish.
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    Emerging contaminant or an old toxin in disguise? Silver nanoparticle impacts on ecosystems.
    (Environ Sci Technol, 2014-05-06) Colman, Benjamin P; Espinasse, Benjamin; Richardson, Curtis J; Matson, Cole W; Lowry, Gregory V; Hunt, Dana E; Wiesner, Mark R; Bernhardt, Emily S
    The use of antimicrobial silver nanoparticles (AgNPs) in consumer-products is rising. Much of these AgNPs are expected to enter the wastewater stream, with up to 10% of that eventually released as effluent into aquatic ecosystems with unknown ecological consequences. We examined AgNP impacts on aquatic ecosystems by comparing the effects of two AgNP sizes (12 and 49 nm) to ionic silver (Ag(+); added as AgNO3), a historically problematic contaminant with known impacts. Using 19 wetland mesocosms, we added Ag to the 360 L aquatic compartment to reach 2.5 mg Ag L(-1). Silver treatments and two coating controls were done in triplicate, and compared to four replicate controls. All three silver treatments were toxic to aquatic plants, leading to a significant release of dissolved organic carbon and chloride following exposure. Simultaneously, dissolved methane concentrations increased forty-fold relative to controls in all three Ag treatments. Despite dramatic toxicity differences observed in lab studies for these three forms of Ag, our results show surprising convergence in the direction, magnitude, and duration of ecosystem-scale impacts for all Ag treatments. Our results suggest that all forms of Ag changed solute chemistry driving transformations of Ag which then altered Ag impacts.
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    Silver toxicity across salinity gradients: the role of dissolved silver chloride species (AgCl x ) in Atlantic killifish (Fundulus heteroclitus) and medaka (Oryzias latipes) early life-stage toxicity.
    (Ecotoxicology, 2016-08) Matson, Cole W; Bone, Audrey J; Auffan, Mélanie; Lindberg, T Ty; Arnold, Mariah C; Hsu-Kim, Heileen; Wiesner, Mark R; Di Giulio, Richard T
    The influence of salinity on Ag toxicity was investigated in Atlantic killifish (Fundulus heteroclitus) early life-stages. Embryo mortality was significantly reduced as salinity increased and Ag(+) was converted to AgCl(solid). However, as salinity continued to rise (>5 ‰), toxicity increased to a level at least as high as observed for Ag(+) in deionized water. Rather than correlating with Ag(+), Fundulus embryo toxicity was better explained (R(2) = 0.96) by total dissolved Ag (Ag(+), AgCl2 (-), AgCl3 (2-), AgCl4 (3-)). Complementary experiments were conducted with medaka (Oryzias latipes) embryos to determine if this pattern was consistent among evolutionarily divergent euryhaline species. Contrary to Fundulus data, medaka toxicity data were best explained by Ag(+) concentrations (R(2) = 0.94), suggesting that differing ionoregulatory physiology may drive observed differences. Fundulus larvae were also tested, and toxicity did increase at higher salinities, but did not track predicted silver speciation. Alternatively, toxicity began to increase only at salinities above the isosmotic point, suggesting that shifts in osmoregulatory strategy at higher salinities might be an important factor. Na(+) dysregulation was confirmed as the mechanism of toxicity in Ag-exposed Fundulus larvae at both low and high salinities. While Ag uptake was highest at low salinities for both Fundulus embryos and larvae, uptake was not predictive of toxicity.