The effects of silver nanoparticles on fathead minnow ( Pimephales promelas) embryos
Abstract
With the commercial explosion of products containing silver (Ag) nanoparticles (NPs) there is clearly a need to understand the risk they may pose to biological systems. Little is known about behavior of NPs under dynamic environmental conditions and effects on aquatic species. The research in this dissertation focused on developing biomarkers to test the toxicity of NPs to assist in filling the present knowledge gap on the effects of these particles. We investigated the effects that Ag NPs exert on a sentinel aquatic species by using the fathead minnow (Promephales promulus) embryo as a test model. Initially, commercial Ag NPs to be used in the study were characterized in terms of size, distribution, the concentration of dissolved Ag they released and the tendency to aggregate over time. The effects of Ag NPs on development of the fathead minnow embryo was investigated with endpoints such as mortality and phenotypic defects using two methods of preparation (sonicated and stirred), comparing calculated LC50 values for the two types of AgNPs compared to a previously defined toxicant AgNO3. The concentration of dissolved Ag released from Ag NPs was determined, separated utilized to investigate the influence of both the particulate form and dissolved forms of Ag on uptake, osmoregulation through Na+ inhibition and genotoxic effects (DNA damage) over time in acute toxicity tests. We determine that AgNPs are seen to cause mortality/defects in fathead minnow embryos, show a genotoxic effect that is measurable by FCM and are also show a strong concentration dependent uptake over time. The effects of AgNPs seem to be coupled to the dissolved Ag released during exposures; however results indicate that both the particulate and dissolved forms may also have independent mechanisms of affecting osmoregulation in fathead minnow embryos. Collectively, these results provides vital information in better understanding the detrimental effects of Ag NPs leaching from nanoproducts and emphasize the need for more research to be done especially when used to advise regulatory bodies on the use of AgNPs commercially. Our work also lays the framework for future studies to further investigate the molecular mechanisms of the effects in aquatic systems.
Degree
Ph.D.
Advisors
Bickham, Purdue University.
Subject Area
Ecology|Toxicology|Surgery|Environmental Studies
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