Project description:Polychlorinated diphenyl ethers are lipophilic, persistent, and bioaccumulable compounds widely used as flame-retardants. These are chemicals of increasing environmental concern due to their lipophilic, persistent, and bioaccumulable characteristics. The objective of this study was to analyze the potential bioavailability and bioaccumulation of BDE-209 as a source of toxicity. Zebrafish embryos were exposed for 8 days to sediments spiked with an environmentally relevant concentration of BDE-209. We analyzed gene expression changes, thyroid function, and several markers for neurotoxicity. Results of this research highlight the need to consider the capability of BDE-209 to be bioavailable and bioaccumulate, indicating the potential hazardous effects.
Project description:Polychlorinated diphenyl ethers are lipophilic, persistent, and bioaccumulable compounds widely used as flame-retardants. These are chemicals of increasing environmental concern due to their lipophilic, persistent, and bioaccumulable characteristics. The objective of this study was to analyze the potential bioavailability and bioaccumulation of BDE-209 as a source of toxicity. Zebrafish embryos were exposed for 8 days to sediments spiked with an environmentally relevant concentration of BDE-209. We analyzed gene expression changes, thyroid function, and several markers for neurotoxicity. Results of this research highlight the need to consider the capability of BDE-209 to be bioavailable and bioaccumulate, indicating the potential hazardous effects. Total RNA was isolated using RNeasy kits (Qiagen, Valencia, CA, USA). The RNA quality was assessed with an Agilent 2100 Bioanalyzer (Agilent, Wilmington, DE, USA) and quantity was determined using a NanodropM-BM-. ND-1000 spectrophotometer. Total RNA was stored at -80oC until analyzed with oligonucleotide microarrays. Zebrafish 44,000 gene arrays (Agilent Single Color 19161, Platform number GPL6457) were purchased from Agilent (Sta. Clara, CA, USA). The Agilent one-color microarray hybridization protocol (One-Color Microarray-Based Gene Expression Analysis, version 5.7, Agilent Technologies, Palo Alto, CA) was used for microarray hybridizations following the manufacturerM-bM-^@M-^Ys protocol and recommendations. Four controls and four treated samples were analyzed, each sample consisting of a pool of embryos. One ug of total RNA was used for all hybridizations. cDNA synthesis, cRNA labeling, amplification and hybridization were performed following the manufacturerM-bM-^@M-^Ys kits and protocols (Quick Amp Labeling kit; Agilent, Palo Alto, CA). An Axon GenePixM-BM-. 4000B Microarray Scanner (Molecular Devices Inc., Sunnyvale, CA) was used to scan microarray images at 5 M-NM-<m resolution. Data were resolved from microarray images using Agilent Feature Extraction software and analyzed using GeneSpring (Agilent Technologies, Palo Alto, CA).
Project description:Methylmercury (MeHg) is an environmental neurotoxicant known to cause adverse effects in fish, such as locomotor abnormalities, visual deficits or teratogenesis. However, very few studies have investigated the effects of environmentally realistic MeHg exposures on the gene expression of fish embryos. Since the primary source of MeHg exposure in wild fish is through the diet, this study analyzed differential gene expression in zebrafish embryos from parents that had been subjected to environmentally relevant dietary MeHg exposures (0, 1, 3, and 10ppm) throughout their whole life cycle.
Project description:The phenylpyrazole fipronil is a widely used insecticide designed to inhibit γ -amino-butyric acid (GABA) receptors, the major inhibitory neurotransmitter in the central nervous system. Fipronil has been detected in some water systems in the ng/L range, and is reported to be neurotoxic. To address the risks associated with fipronil exposure, we measured morphological, physiological, and molecular responses in zebrafish (Danio rerio) embryos following a 48 hour exposure (20 ng/L – 2 mg/L). Survival was not different than controls following treatments below 200 µg fipronil/L but was ~20% higher with concentrations above 200 µg fipronil/L. Once the embryos hatched, they underwent a 7 day depuration phase. At 9 days post-fertilization (9 dpf), body length and notochord length were not different than controls for any dose. To assess sub-lethal effects, transcriptome profiling was conducted in 9 dpf larvae following 48 hour exposure + 7 dpf depuration to environmentally relevant concentrations of fipronil (200 ng fipronil/L), as well as two higher concentrations of the pesticide (200 µg fipronil/L and 2 mg fipronil/L). Transcriptome profiling revealed that all three concentrations affected pathways related to chromosome condensation and the metabolism of estrogens and androgens as well as genes related to methylation. In addition, 200 ng fipronil/L down-regulated genes related to the circadian clock, histone and DNA methylation, and histone acetylation, while the highest dose increased networks related to immune function (e.g. lectin-induced complement pathway and the alternative complement pathway). The two highest concentrations of fipronil increased the expression of transcriptional networks associated with mitochondrial respiratory chain dysfunction and mitochondrial protein transport. As such, we exposed 24 hpf embryos to fipronil for 24 hours and measured oxygen consumption rate to assess mitochondrial function. There were no differences in basal and maximal respiration in the embryos nor ATP production, and fipronil did not affect mitochondrial bioenergetics. This study suggests that fipronil at environmentally relevant concentrations does not adversely affect the survival or morphology of fish embryos, however sub-lethal endpoints should be examined to more fully characterize the long term effects of fipronil exposure in larval fish.
Project description:Polybrominated diphenyl ethers (PBDEs) are persistent organic chemicals implied as flame re-tardants. Humans are mainly exposed to BDE-47, -99 and -209 congeners by diet. PBDEs are metabolic disruptors with liver as main target organ. To investigate their mode of action at a human relevant concentration, we exposed HepG2 cells to these congeners and their mixture at 1 nM for 72h, analyzing their transcriptomic and proteomic profiles. KEGG pathways and GSEA Hallmarks enrichment analyses evidenced that BDE-47 disrupted the glucose metabolism and Hypoxia pathway; all the congeners and the MIX affected lipid metabolism and signaling Hallmarks regulating metabolism as mTORC1 and PI3K/AKT/MTOR. These results were confirmed by glucose secretion depletion and increased lipid accumulation, especially in BDE-47 and -209 treated cells. These congeners also affected the EGFR/MAPK signaling; further, BDE-47 enriched the Estrogen pathway. Interestingly, BDE-209 and the MIX increased ERα gene expression, whereas all the congeners and the MIX induced ERβ and PPARγ. We also found that PBDEs modulated several lncRNAs and that HNRNAP1 represented a central hub in all the four interaction networks. Overall, despite the low concentration used, the PBDEs investigated affected glucose and lipid metabolism with different underlying modes of action, as highlighted by the integrated omics analysis. These results may support the mechanism-based risk assessment of these compounds in relation to liver metabolism disruption.
Project description:Flame retardants are detected globally in the environment, and pose great risks to human health. The potential effects of these chemicals on the development of nervous system have raise public concerns. In this study, to explore the toxicity profiles of these chemicals in the early developmental stage of human nervous system, we induced neural ectoderm from human embryonic stem cells in the presence of individual or mixture of BDE-47, BDE-209, TBBPA, TBBPS, TCBPA. By analyzing the whole transcriptional changes in the samples treated with 1 μΜ of each chemical, we identified a set of neural development relative biological processes that response to these chemicals. Genes involved in the GO terms relative to neural development were further confirmed by qRT-PCR assay, with samples treated with various concentrations (10 nM, 100 nM, 1 μΜ, 5 μΜ) of these chemicals. We found out that axon guidance and synaptogenesis may be the major target of these chemicals. In addition, these flame retardants may dysregulate the WNT and AHR signaling pathways. BDE-209 showed similar toxicity with BDE-47, whereas TBBPS and TCBPA may not be safe alternatives to TBBPA.
Project description:Polybrominated diphenyl ethers (PBDEs) were used as flame-retardant additives in a wide range of polymers starting in 1965 and were recently withdrawn from commerce in North America and Europe. Generations that were exposed perinatally to the highest environmental doses of PBDE have now reached 5-20 years of age and in the U.S. account for 1/5 of the total population. Emerging data indicates long-term impairment of metabolic health by PBDE exposure in humans and laboratory animals. We hypothesize that exposure to PBDE during sensitive developmental windows may result in long-lasting changes in liver metabolism. In this study pregnant CD-1 mice were exposed to 0.2 mg/kg 2,2’,4,4’-tetrabromodiphenyl ether (BDE-47) from gestation day 8 till postnatal day 21 and liver RNA-seq was performed on the last day of dam exposure and on postnatal week 20 in male offspring. Several groups of metabolic genes, including ribosomal and mitochondrial genes were significantly upregulated at both time-points. Genes regulated via mechanistic target of rapamycin (mTOR pathway), the gatekeeper of metabolic homeostasis, were whether up- or down- regulated at both time-points. Thus, perinatal exposure to environmentally relevant doses of BDE-47 in laboratory mice results in long-lasting changes in liver metabolism. Our evidence suggests involvement of the mTOR pathway in the observed metabolic programming of liver.
Project description:Numerous studies report active pharmaceutical compounds detected in both wastewater effluent and surface waters. Exposure to statin drugs in general, and atorvastatin in particular, is likely to be a concern. We hypothesized that chronic exposure to low concentrations of atorvastatin in water would result in an adverse effect on production of steroids regulating growth and development of the model amphibian Xenopus laevis. To assess the potential for impacts we used three experimental assays. The FETAX assay was used to evaluate the effects of a range of doses of atorvastatin on developing embryos. A 60 day metamorphosis assay assessed the effects of aqueous atorvastatin exposure at environmentally concentrations on metamorphosing tadpoles. A 60 day chronic flow-through exposure evaluated the effects of chronic low concentrations of atorvastatin on adults. The data from the FETAX assay confirmed uptake, activity, and effect of atorvastatin in X. laevis tadpoles. The results of the 60-day flow-through exposure on metamorphosing tadpoles showed significant evidence of altered cholesterol biosynthesis. The dose-dependent increase in cyp19a1 expression also indicated that the steroidogenesis pathway was affected. The RNAseq analysis confirmed that exposure to environmentally relevant concentrations of atorvastatin does cause significant alterations to global transcriptional profiles in a manner consistent with dysregulation of the cholesterol biosynthesis pathway, both through the downregulation of many genes involved in that pathway, but also in the impacts to other, related pathways. The qPCR data for both adult males and adult females indicated only slight changes in expression with the exception that hmgcr was significantly downregulated in males, and cyp3a4 expression was significantly downregulated in females. The data we present here indicated that chronic exposure to environmentally relevant concentrations of atorvastatin does have the potential to impact early life stage frogs, particularly by altering expression of genes involved in critical molecular pathways.