Mixture effects in samples of multiple contaminants - An inter-laboratory study with manifold bioassays.

Chemicals in the environment occur in mixtures rather than as individual entities. Environmental quality monitoring thus faces the challenge to comprehensively assess a multitude of contaminants and potential adverse effects. Effect-based methods have been suggested as complements to chemical analytical characterisation of complex pollution patterns.

Hepatic transcriptional responses to copper in the three-spined stickleback are affected by their pollution exposure history.

Some fish populations inhabiting contaminated environments show evidence of increased chemical tolerance, however the mechanisms contributing to this tolerance, and whether this is heritable, are poorly understood. We investigated the responses of two populations of wild three-spined stickleback (Gasterosteus aculeatus) with different histories of contaminant exposure to an oestrogen and copper, two widespread aquatic pollutants. Male stickleback originating from two sites, the River Aire, with a history of complex pollution discharges, and Siblyback Lake, with a history of metal contamination, were depurated and then exposed to copper (46μg/L) and the synthetic oestrogen ethinyloestradiol (22ng/L).

Molecular toxicity of cerium oxide nanoparticles to the freshwater alga Chlamydomonas reinhardtii is associated with supra-environmental exposure concentrations.

Ceria nanoparticles (NPs) are widely used as fuel catalysts and consequently are likely to enter the environment. Their potential impacts on. biota at environmentally relevant concentrations, including uptake and toxicity, remain to be elucidated and quantitative data on which to assess risk are sparse.

Molecular basis of carcinogenicity of tungsten alloy particles.

The tungsten alloy of 91% tungsten, 6% nickel and 3% cobalt (WNC 91-6-3) induces rhabdomyosarcoma when implanted into a rat thigh muscle. To investigate whether this effect is species-specific human HSkMc primary muscle cells were exposed to WNC 91-6-3 particles and responses were compared with those from a rat skeletal muscle cell line (L6-C11). Toxicity was assessed by the adenylate kinase assay and microscopy, DNA damage by the Comet assay.

Molecular responses of European flounder (Platichthys flesus) chronically exposed to contaminated estuarine sediments.

Molecular responses to acute toxicant exposure can be effective biomarkers, however responses to chronic exposure are less well characterised. The aim of this study was to determine chronic molecular responses to environmental mixtures in a controlled laboratory setting, free from the additional variability encountered with environmental sampling of wild organisms. Flounder fish were exposed in mesocosms for seven months to a contaminated estuarine sediment made by mixing material from the Forth (high organics) and Tyne (high metals and tributyltin) estuaries (FT) or a reference sediment from the Ythan estuary (Y).

The toxicological application of transcriptomics and epigenomics in zebrafish and other teleosts.

Zebrafish (Danio rerio) is one of a number of teleost fish species frequently employed in toxicology. Toxico-genomics determines global transcriptomic responses to chemical exposures and can predict their effects. It has been applied successfully within aquatic toxicology to assist in chemical testing, determination of mechanisms and environmental monitoring.

Transcriptomic responses of European flounder (Platichthys flesus) liver to a brominated flame retardant mixture.

Male European flounder (Platichthys flesus) were exposed to a technical mixture of brominated diphenyl ethers (PDBEs, DE-71, Pentamix) that had been purified to remove contaminating dioxins. Controls were exposed to carrier solvent alone. Fish were exposed to decadally increasing concentrations of Pentamix via both sediment and spiked food.

Disruption of DNA methylation via S-adenosylhomocysteine is a key process in high incidence liver carcinogenesis in fish.

Interactions between epigenome and the environment in biology and in disease are of fundamental importance. The incidence of hepatocellular adenomas in flatfish exceeds 20% in some environments forming a unique opportunity to study environmental tumorigenesis of general relevance to cancer in humans. We report the novel finding of marked DNA methylation and metabolite concentration changes in histopathologically normal tissue distal to tumors in fish liver.

Gene expression and epigenetic changes by furan in rat liver.

Furan, a widely used industrial compound, has been found in a number of heated food items. Furan is carcinogenic to rats and mice, but the mechanism behind its carcinogenic effect is still not well understood. In this study, we tested the hypothesis that alteration of gene expression relating to cell cycle, apoptosis, DNA damage and of epigenetic modifications including miRNA and DNA methylation may contribute to rodent carcinogenicity of furan.

Towards a system level understanding of non-model organisms sampled from the environment: a network biology approach.

The acquisition and analysis of datasets including multi-level omics and physiology from non-model species, sampled from field populations, is a formidable challenge, which so far has prevented the application of systems biology approaches. If successful, these could contribute enormously to improving our understanding of how populations of living organisms adapt to environmental stressors relating to, for example, pollution and climate. Here we describe the first application of a network inference approach integrating transcriptional, metabolic and phenotypic information representative of wild populations of the European flounder fish, sampled at seven estuarine locations in northern Europe with different degrees and profiles of chemical contaminants.

Integrating omic technologies into aquatic ecological risk assessment and environmental monitoring: hurdles, achievements, and future outlook.

Background: In this commentary we present the findings from an international consortium on fish toxicogenomics sponsored by the U.K. Natural Environment Research Council (Fish Toxicogenomics-Moving into Regulation and Monitoring, held 21-23 April 2008 at the Pacific Environmental Science Centre, Vancouver, BC, Canada).

Identifying health impacts of exposure to copper using transcriptomics and metabolomics in a fish model.

Copper (Cu) is a micronutrient essential for the biochemical functioning of numerous processes in vertebrates but is also often present in the aquatic environment at concentrations able to cause adverse health effects in aquatic organisms. This study investigated the signaling pathways mediating the effects of exposure to Cu using a toxicogenomic approach in a fish model, the stickleback ( Gasterosteus aculeatus ). Freshwater-acclimated male fish were exposed via the water to Cu, including at environmentally relevant concentrations (3.

Hepatic gene expression in flounder chronically exposed to multiply polluted estuarine sediment: Absence of classical exposure 'biomarker' signals and induction of inflammatory, innate immune and apoptotic pathways.

The effects of chronic long-term exposure to multiply polluted environments on fish are not well understood, but environmental surveys suggest that such exposure may cause a variety of pathologies, including cancers. Transcriptomic profiling has recently been used to assess gene expression in European flounder (Platichthys flesus) living in several polluted and clean estuaries. However, the gene expression changes detected were not unequivocally elicited by pollution, most likely due to the confounding effects of natural estuarine ecosystem variables.

Hepatic transcriptomic and metabolomic responses in the stickleback (Gasterosteus aculeatus) exposed to environmentally relevant concentrations of dibenzanthracene.

A three-spined stickleback (Gasterosteus aculeatus) cDNA array and one-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy-based metabolomics approach, together with individual biomarkers,were employed to investigate the responses of male sticklebacks to polycyclic aromatic hydrocarbon exposure. Fish were exposed to 1,2:5,6-dibenzanthracene (DbA) at concentrations between 0.01 and 50 microg per liter dissolved in the ambient water for four days, and hepatic transcript and metabolite profiles were determined in comparison with those of solvent-exposed controls.

Hepatic transcriptomic and metabolomic responses in the Stickleback (Gasterosteus aculeatus) exposed to ethinyl-estradiol.

An established three-spined stickleback (Gasterosteus aculeatus) cDNA array was expanded to 14,496 probes with the addition of hepatic clones derived from subtractive and normalized libraries from control males and males exposed to model toxicants. Microarrays and one-dimensional (1)H nuclear magnetic resonance (NMR) spectroscopy, together with individual protein and gene biomarkers were employed to investigate the hepatic responses of the stickleback to ethinyl-estradiol (EE(2)) exposure. Male fish were exposed via the water to EE(2), including environmentally relevant concentrations (0.

Comparative aquatic toxicity of propranolol and its photodegraded mixtures: algae and rotifer screening.

Transformation products of pharmaceuticals formed by human metabolism within sewage treatment plant or receiving waters are predicted, in most cases, to be less toxic than the parent compound to common aquatic species. However, there is little available data to demonstrate whether this is generally the case. In the present study, a framework was developed to guide testing of transformation products using phototransformation of the beta-blocker propranolol to test the hypothesis for this particular transformation route.

Changes in gene expression and assessment of DNA methylation in primary human hepatocytes and HepG2 cells exposed to the environmental contaminants-Hexabromocyclododecane and 17-beta oestradiol.

We evaluated the effects of two putative non-genotoxic hepatic carcinogens, hexabromocyclododecane (HBCD) and 17-beta oestradiol (E(2)) on global and CpG promoter DNA methylation in both primary human hepatocytes and hepatocellular carcinoma (HepG2) cells. The mRNA gene expression levels of genes involved particularly in cell cycle were also evaluated and potential correlation with DNA methylation status examined. HBCD at 0.

Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants.

The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 microg/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert-butyl-hydroperoxide (5 mg/kg in saline), Lindane (25mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments.

High-throughput functional annotation and data mining with the Blast2GO suite.

Functional genomics technologies have been widely adopted in the biological research of both model and non-model species. An efficient functional annotation of DNA or protein sequences is a major requirement for the successful application of these approaches as functional information on gene products is often the key to the interpretation of experimental results. Therefore, there is an increasing need for bioinformatics resources which are able to cope with large amount of sequence data, produce valuable annotation results and are easily accessible to laboratories where functional genomics projects are being undertaken.

Global genomic methylation levels in the liver and gonads of the three-spine stickleback (Gasterosteus aculeatus) after exposure to hexabromocyclododecane and 17-beta oestradiol.

Alteration of DNA methylation is a major epigenetic mechanism associated with the effects of nongenotoxic carcinogens. We evaluated the effects of two environmental pollutants, hexabromocyclododecane (HBCD), 17-beta oestradiol (E(2)) as well as 5-aza 2' deoxycytidine (5AdC) on global DNA methylation levels (5-methyl 2' deoxycytidine) in the liver and gonads of the three-spine stickleback (Gasterosteus aculeatus). HBCD at 30 and 300 ng/L of water did not produce statistically significant differences in global genomic methylation in liver of female stickleback.

Evaluation of the reproductive effects of tamoxifen citrate in partial and full life-cycle studies using fathead minnows (Pimephales promelas).

Laboratory studies were conducted to investigate potential adverse effects on development, growth, reproduction and biomarker responses (vitellogenin [VTG] and gonad histology) in fathead minnows (Pimephales promelas) exposed to tamoxifen citrate. Based on the results of a partial life cycle study (nominal [mean measured] concentrations ranged from 0.18 [0.

Gene expression responses of European flounder (Platichthys flesus) to 17-beta estradiol.

Male European flounder (Platichthys flesus) were intraperitoneally injected with 10mg/kg 17-beta estradiol and tissues taken from individuals over a timecourse of 16 days. The GENIPOL P. flesus cDNA microarray was employed to detect hepatic gene expression differences between fish treated with estradiol and saline controls.

Development of the GENIPOL European flounder (Platichthys flesus) microarray and determination of temporal transcriptional responses to cadmium at low dose.

We have constructed a high density, 13 270-clone cDNA array for the sentinel fish species European flounder (Platichthys flesus), combining clones from suppressive subtractive hybridization and a liver cDNA library; DNA sequences of 5211 clones were determined. Fish were treated by single intraperitoneal injection with 50 micrograms cadmium chloride per kilogram body weight, a dose relevant to environmental exposures, and hepatic gene expression changes were determined at 1, 2, 4, 8, and 16 days postinjection in comparison to saline-treated controls. Gene expression responses were confirmed by real-time reverse transcription polymerase chain reaction (RT-PCR).

Functional analysis of a metal response element in the regulatory region of flounder cytochrome P450 1A and implications for environmental monitoring of pollutants.

Cytochrome P450 1A (CYP 1A) is a member of a multigene family of xenobiotic metabolizing enzymes. CYP 1A is highly inducible by numerous environmental contaminants including polycyclic aromatic hydrocarbons (PAHs) and is widely used in biomonitoring studies. Therefore, understanding the regulation of this gene is important for accurate interpretation of biomarker data.