Variability in Nontarget Terrestrial Plant Studies Should Inform Endpoint Selection.

Inherent variability in nontarget terrestrial plant (NTTP) testing of pesticides creates challenges for using and interpreting these data for risk assessment. Standardized NTTP testing protocols were initially designed to calculate the application rate causing a 25% effect (ER25, used in the United States) or a 50% effect (ER50, used in Europe) for various measures based on the observed dose-response. More recently, the requirement to generate a no-observed-effect rate (NOER), or, in the absence of an NOER, the rate causing a 5% effect (ER05), has raised questions about the inherent variability in, and statistical detectability of, these tests.

The G Protein-Coupled Estrogen Receptor Agonist G-1 Inhibits Nuclear Estrogen Receptor Activity and Stimulates Novel Phosphoproteomic Signatures.

Estrogen exerts cellular effects through both nuclear (ESR1 and ESR2) and membrane-bound estrogen receptors (G-protein coupled estrogen receptor, GPER); however, it is unclear if they act independently or engage in crosstalk to influence hormonal responses. To investigate each receptor's role in proliferation, transcriptional activation, and protein phosphorylation in breast cancer cells (MCF-7), we employed selective agonists for ESR1 propyl-pyrazole-triol (PPT), ESR2 diarylpropionitrile (DPN), and GPER (G-1) and also determined the impact of xenoestrogens bisphenol-A (BPA) and genistein on these effects. As anticipated, 17β-estradiol (E2), PPT, DPN, BPA, and genistein each enhanced proliferation and activation of an ERE-driven reporter gene whereas G-1 had no significant impact.

Application of a label-free, gel-free quantitative proteomics method for ecotoxicological studies of small fish species.

Although two-dimensional electrophoresis (2D-GE) remains the basis for many ecotoxicoproteomic analyses, newer non-gel-based methods are beginning to be applied to overcome throughput and coverage limitations of 2D-GE. The overall objective of our research was to apply a comprehensive, liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomic approach to identify and quantify differentially expressed hepatic proteins from female fathead minnows exposed to fadrozole, a potent inhibitor of estrogen synthesis. Female fathead minnows were exposed to 0 (control), 0.

Proteomics in aquatic amphipods: can it be used to determine mechanisms of toxicity and interspecies responses after exposure to atrazine?

Proteomics has gained popularity in the field of ecotoxicology as a holistic tool for unraveling novel mechanisms of toxicity and elucidating subtle effects of contaminant exposure. The holoarctic amphipod Diporeia spp. is declining at precipitous rates in the Great Lakes, and we are evaluating the use of the well-studied amphipod model Hyalella azteca as a surrogate for Diporeia spp.

The use of two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOF-MS) for metabolomic analysis of polar metabolites.

Metabolites produced by an organism can be quite extensive, and one analytical technique alone is not capable of their comprehensive detection and identification. The majority of environmental metabolomic studies have implemented proton nuclear magnetic resonance ((1)H-NMR) spectroscopy with little attention given to mass spectrometry (MS) techniques. In this chapter, an analytical technique is outlined that incorporates two-dimensional gas chromatography-time-of-flight MS (GC×GC-TOF-MS) for the identification and quantification of polar metabolites.