Project description:Fathead minnow and zebrafish are among the most intensively studied fish species in environmental toxicogenomics. To aid the assessment and interpretation of subtle transcriptomic effects from treatment conditions of interest, there needs to be a better characterization and understanding of the natural variation in gene expression among fish individuals within populations. Little effort, however, has been made in this area. Leveraging the transcriptomics data from a number of our toxicogenomics studies conducted over the years, we conducted a meta-analysis of nearly 600 microarrays generated from the ovary tissue of untreated, reproductively mature fathead minnow and zebrafish samples. As expected, there was considerable batch-to-batch transcriptomic variation; this “batch-effect” appeared to impact the fish transcriptomes randomly. The overall level of variation within-batch was quite low in fish ovary tissue, making it a suitable system for studying chemical stressors with subtle biological effects. The within-batch variation, however, differed considerably among individual genes and molecular pathways. This difference in variability is probably both technical and biological, thus suggesting a need to take into account both the expression levels and variance in evaluating and interpreting the transcriptional impact on genes and pathways by experimental conditions. There was significant conservation of both the genomes and transcriptomes between fathead minnow and zebrafish. The conservation to such a degree would enable not only a comparative biology approach in studying the mechanisms of action underlying environmental stressors, but also effective sharing of a large amount of existing public transcriptomics data for future development of toxicogenomics applications. total RNA from the ovary tissue of treated or control fish labeled in single color was hybridized to Agilent fathead minnow microarray (design 019597)
Project description:Fathead minnow and zebrafish are among the most intensively studied fish species in environmental toxicogenomics. To aid the assessment and interpretation of subtle transcriptomic effects from treatment conditions of interest, there needs to be a better characterization and understanding of the natural variation in gene expression among fish individuals within populations. Little effort, however, has been made in this area. Leveraging the transcriptomics data from a number of our toxicogenomics studies conducted over the years, we conducted a meta-analysis of nearly 600 microarrays generated from the ovary tissue of untreated, reproductively mature fathead minnow and zebrafish samples. As expected, there was considerable batch-to-batch transcriptomic variation; this “batch-effect” appeared to impact the fish transcriptomes randomly. The overall level of variation within-batch was quite low in fish ovary tissue, making it a suitable system for studying chemical stressors with subtle biological effects. The within-batch variation, however, differed considerably among individual genes and molecular pathways. This difference in variability is probably both technical and biological, thus suggesting a need to take into account both the expression levels and variance in evaluating and interpreting the transcriptional impact on genes and pathways by experimental conditions. There was significant conservation of both the genomes and transcriptomes between fathead minnow and zebrafish. The conservation to such a degree would enable not only a comparative biology approach in studying the mechanisms of action underlying environmental stressors, but also effective sharing of a large amount of existing public transcriptomics data for future development of toxicogenomics applications.
Project description:Despite major successes in reducing the risks of lead (Pb) exposure over the past few decades, two issues of considerable importance remain unresolved: (1) how differences in water chemistry influence acute and chronic Pb toxicity, and (2) the elucidation of specific toxic mechanisms and modes of action (MOA). To more clearly define the water chemistry parameters mediating Pb toxicity we evaluated the effects of hardness (as CaSO4) and DOC (as humic acid (HA)) during chronic (150d) exposures to the fathead minnow (Pimephales promelas). Traditional toxicological endpoints were examined alongside gene expression analyses to help clarify the underlying mechanisms and MOA of Pb toxicity and to identify robust molecular markers of exposure and effect. Keywords: time course, chronic lead (Pb) exposure To analyze the gene expression responses to low-level Pb exposures fish were exposed +/- Pb in low ionic strength base water and fish collected at 2d, 4d, 10d, and 30d for microarray analysis. Equal amounts of RNA from all no lead controls were pooled (18 fish total for 2d & 4d exposures; 12 fish total for 10d & 30d exposures) as reference samples for hybridization with each of 3 separate biological replicate pools (6 fish total for 2d & 4d exposures; 4 fish total for 10d & 30d exposures) of RNA from age-matched, lead-exposed fish. Each pair of hybridizations was repeated with dye-swaps. Additional repeats were performed for various arrays to ensure quality of data obtained from initial hybridization.
Project description:Prioritization of Contaminants of Emerging Concern in wastewater treatment plant discharges using transcriptional effects in caged fish
Project description:Derivation and Evaluation of Putative Adverse Outcome Pathways for the Effects of Cyclooxygenase Inhibitors on Reproductive Processes in Fish
Project description:Prior Knowledge-based Approach for Associating Emerging Contaminants with Effects in Fish Exposed In Situ: A Case Study in the St. Croix River Basin, MN, WI, USA.
Project description:Diethylstilbestrol (DES) is a synthetic estrogen that has been banned for use in humans, but still is employed in livestock and aquaculture operations in some parts of the world. Detectable concentrations of DES in effluent and surface waters have been reported to range from slightly below 1 to greater than 10 ng/L. Little is known, however, concerning the toxicological potency of DES in fish. In this study, sexually-mature fathead minnows (Pimephales promelas) of both sexes were exposed to 1, 10 or 100 ng DES/L water in a flow-through system. Tissue concentrations of DES and changes in a number of estrogen-responsive endpoints, including alterations to the hepatic transcriptome in females, were measured in the fish at the end of a 4-d exposure, and after a 4-d depuration/recovery period in clean water. The objectives of the study were to measure accumulation of DES in fish tissues, characterize effects of the chemical on physiological endpoints related to reproductive performance, and to evaluate DES's potency relative to concentrations reported in aquatic environments. The current series includes n=12 microarrays associated with exposure-phase samples (collected from fish exposed continuously for 4 d).