Project description:Paper Abstract. Extrapolating toxicological sensitivity information across species can require the use of highly conservative safety factors as prescribed by ecological risk assessment protocols. The objective of our study was to use multipule factors to understand the dynamics of stress responses by comparing ecotoxicological, developmental, and genomic data to quantitatively determine the relative sensitivity of two common model aquatic vertebrates to assess the potential for developing refined safety factors among species. Larval (3-d old) zebrafish (Danio rerio) and fathead minnows (Pimephales promelas) were concurrently exposed in 96-h static exposures to the widely-used military energetic compound cyclotrimethylenetrinitramine (RDX). Endpoints assessed included mortality, incidence of vertebral deformities, swimming behavior, and differential gene (transcript) expression. Analytically verified treatment concentrations ranged from 0.9 to 27.7 mg/L RDX. While RDX concentrations prepared for exposures included 0, 0.9, 1.8, 3.5, 7.5, 15.0, and 30.0 mg/L, analytically verified treatment concentrations were 0, 0.88, 1.75, 3.46, 6.96, 13.79, and 27.7 mg/L, respectively. Changes in prepared RDX concentrations and analytically verified treatment concentrations are a result of chemical breakdown, a well known characteristic of RDX Our results indicated a higher sensitivity to RDX in P. promelas than in D. rerio in both mortality (LOECs 13.79 and 27.7 mg/L, respectively) and vertebral deformity (LOECs 13.79 and >13.79, respectively) endpoints. Swimming behavior was assessed in 10 min behavioral trials using Noldus EthoVision® digital tracking software. Swimming behavior trials indicated non-significant trends of decreased velocity, distance moved, and increased meander (change in direction per cm traveled) for P. promelas. No such trends were apparent in D. rerio swimming behavior. A comprehensive genomic analysis is in progress to determine the genes, gene ontology elements, metabolic pathways and metabolic networks affected in common among species in the RDX exposure. Taken as a whole, the ecotoxicological, developmental and genomic results will provide valuable insights into the similarity in response among these fish species to RDX. Three-day-old fathead minnow (FHM, Pimephales promelas) or Zebrafish (ZF, Danio rerio) fry were exposed to either control water or one of six concentrations of RDX (0.9, 1.9, 3.8, 7.5, 15, or 27.7 mg/L) in 96-h exposures. However, microarray analysis was only performed on FHM exposed to 0, 0.9, 1.9, 7.5, or 15 mg/L RDX and ZF exposed to 0, 0.9, 1.9, 3.8, 7.5, or 15 mg/L RDX due to insufficient tissue for microarray analysis due to animal death at the other RDX concentrations. The experimental design was based on the U.S. EPA (2002) acute testing method for P. promelas, test method 2000.0 and included four replicates per treatment with ten fish per replicate. Whole fish (10 fish per replicate) were investigated for differential expression in response to RDX exposure.
2011-02-08 | E-GEOD-27067 | biostudies-arrayexpress
