Unknown,Transcriptomics,Genomics,Proteomics

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Transcriptomic response of zebrafish embryos to Polyamidoamine (PAMAM) dendrimers

ABSTRACT: We are presenting here the application of toxicogenomics to perform the evaluation of toxic effects of two polyamidoamine dendrimers (Generation3 and Generation4) on the developing zebrafish embryo. They are nanomaterials of special concern under the toxicological point of view because of their relatively high solubility in water and bioavailability. Zebrafish embryo toxicity assays (zFET) showed that G3 was more toxic to zebrafish than G4, and that both compounds were several orders of magnitude more toxic than other carbonaceous nanomaterials, like carbon fullerenes or nanotubes. The results suggest a variety of MoA for different dendrimers, probably related to the nature and number of the chemical groups attached to their surface. They also confirm the relatively high bioavailability of these compounds, a key factor for the assessment of the risk associated to their use and release into the environment. About 5% genes were affected by the treatment. Gene ontology (GO) analyses show that these genes are involved in the oxidation-reduction process and also in the nervous system development. Representatives of each GO functional groups were selected and quantified by real-time PCR to validate the microarray data and to differentiate the action of generations of dendrimers studied. Two different treatments were performed in this study. Zebrafish fertlized eggs were exposed to PAMAM dendrimer G3 and G4 during 48h. 3 biological replicates per studied dendrimer are included such as each control sample.

ORGANISM(S): Danio rerio

SUBMITTER: Eva Oliveira

PROVIDER: E-GEOD-41333 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Atmospheric particulate matter (PM) is a recognized risk factor for the global burden of disease in human populations. We are presenting here the application of toxicogenomics in the evaluation of the toxic effects of organic content of atmospheric particle matter (PM), from urban and rural environments (city of Barcelona and village of La Pobla, NE Spain), using the developing zebrafish embryo. The main goal is to identify the metabolic pathways involved in the adverse effects observed in zebrafish embryos exposed to PM organic content from urban and rural environments, also allowing the selection of genes of interest that are differentially expressed. The relevance of particle size to the PM toxicity is also addressed. Indeed, the zebrafish embryos were exposed to PM of aerodynamic diameter larger than 7.2 Î¼m and smaller than 0.5 Î¼m (PM10 and PM0.5, respectively). PM0.5 concentrated biological and toxic activities linked to organic substances. Transcriptomic analyses showed strong induction of the AhR signalling pathway (a.k.a. dioxin-like activity) for embryos exposed to both rural and urban extracts, correlating with the concentrations of PAHs. Urban extracts, with strong contribution of traffic emissions, specifically de-regulated oxidative stress-related genes, as well as pancreatic and eye-lens specific genes, two organs known to be affected by air pollution in humans. Exposure to rural extracts, with high contribution of wood burning emissions, affected genes implicated in basic cellular functions, in agreement with their strong embryotoxicity. Extracts from rural and urban samples elicited both common and specific transcriptome responses, suggesting different potentially adverse outcomes depending on PM source and composition. The authors thank the financial support of the Spanish Ministry (project TEA-PARTICLE, grant number CGL2011-29621) and the Portuguese Foundation for Science and Technology for the doctoral grant of Sofia R. Mesquita (SFRH/BD/80710/2011) funded by the Program POPH-QREN through the Portuguese Ministry of Education and Science and the European Social Fund, and support through project PEst-C/MAR/LA0015/2013. The PM filter samples used in the present study were PM10 and PM0.5 from the urban site - total of 4 samples from 2 sampling months; and PM0.5 from the rural site - total of 2 samples from 2 sampling months (PM10 samples from the rural site were not tested due to their very low concentration in organic compounds, and insignificant biological activity, previously measured). Sampling occurred during the cold periods of the year 2012/2013. The organic fraction of PM samples was extracted by sonication using a mixture of dichloromethane:methanol. Then, the extracts were filtered, evaporated and re-dissolved in Dimethyl sulfoxide (DMSO). Zebrafish fertilized eggs were exposed to PM organic extracts (0.2% DMSO) from the urban and rural sites from 24 to 120h post-fertilization. Total RNA was isolated from whole embryos (pools of 20 individuals), using Trizol reagent protocol (Invitrogen Life Technologies, Carlsberg, CA). The microarray study was performed using the Agilent Two-colour D. rerio Oligo Microarray v3 platform, following the Agilent Microarray â?? Based Gene Expression Analysis protocol. Three biological replicates were performed for each PM sample and controls. Biological replicates, a technical replicate and a self-to-self, were simultaneously amplified and labelled using Cyanine 3 (Cy3) and Cyanine 5 (Cy5) dye. After cRNA purification (RNeasy Kit, Quiagen GmbH, Hilden, Germany), the cRNA concentration and labelling were quantified in the NanoDrop spectrophotometer, obtaining incorporation rates in the range of 15-20pmol of cyanide dye/Âµl cRNA and yield values > 0.825ug, as recommended. cRNA was fragmented and hybridized in 4x44K arrays, for 17h at 65oC. After the hybridization the array slides were washed, and immediately scanned using Microarray Scanner Agilent G2505C system. Data was extracted using Agilent Feature Extraction Software v10.5.1.1, and the quality of microarray data was evaluated using the Quality Control report provided by Agilent Software. Based on the microarray data analysis, 22 primers were selected and designed using Primer Express 2.0 software (Applied Biosystems, Foster City, CA). Genes were quantified by real-time PCR to validate the microarray data, and a subset of 13 genes were further selected by their robust behaviour in the validation assays, allowing to differentiate the toxic potential of PM from urban and rural sources.

Project description:Within the regulatory framework on the approval of new substances, the assessment of immunotoxic modes of action (MoA) is currently not covered. This is not least due to the lack of standardized methods and reliable validated biomarkers for immunotoxic effects. The experimental set up was designed to analyze the compound-specific response of zebrafish embryos to two immunomodulative reference substances, clobetasol propionate (CP, CAS 25122-46-7) and imiquimod (IMQ, CAS 99011-02-6), on the global level of gene expression. The obtained results were used to (i) identify potential biomarker candidates for the assessment of immunotoxic MoAs, (ii) identify compound-specific molecular signatures, (iii) evaluate the reliability of data acquisition using OMICs-coupled approaches and (iv) to assess the suitability of the zebrafish embryo as an alternative model for the human-representative investigation of psoriatic effects. For this, the transcriptomic profiles of embryos were bioinformatically analysed subsequent to an CP-induced immunosuppression in absence or presence of an IMQ-induced immune challenge, i.e. the simulation of a resting and an activated immune system. In a modified version of the zebrafish embryo toxicity test (OECD 236), 15 fertilized eggs were exposed to either CP (250 nM) or to IMQ (4000 nM) or to a combination of both under semi static conditions. Exposure to CP started at 2 hours post fertilization (hpf) until 72 hpf. Exposure to IMQ started at 48 hpf until 72 hpf. Untreated embryos reared in medium without CP nor IMQ dissolved was used as a negative control. All conditions comprised three biological replicates. Medium was exchanged on a daily basis by renewing half its volume. Occurrence of morphological changes and indicators of lethality as described in the OECD test guideline 236 were examined microscopically on a daily basis. At 72 hpf, all larvae were pooled for each sample for RNA extraction using a NucleoSpin RNA/Protein kit (Macherey-Nagel) following the manufacturer’s protocol. RNA quality was assessed with a 2100 Bioanalyzer system (Agilent) before coding RNA was purified (PolyA selection with TruSeq RNA Library Prep Kit v2) and sequenced on an Illumina NovaSeq 6000 System (Illumina) in 150 bp paired-end mode, producing a minimum of 30 million reads per sample. Adapter sequences were removed with trimmomatic and sequences were aligned to the Danio rerio reference genome GRCz11 with STAR. Counting of feature mapped reads was performed through featureCounts. Library gene count tables were then merged to a single count matrix as input for differential gene expression analysis with DESeq2.

Project description:DRM is a conserved transcription factor complex that includes E2F/DP and pRB family proteins and plays important roles in development and cancer. Here we perform microarray expression profiling analysis of lin-54, a DNA-binding member of the DRM complex. To identify genes regulated by LIN-54 in soma and germline, we analyzed wild-type and lin-54 mutant C. elegans embryos and isolated germlines. We chose embryos because they consist primarily of somatic cells, at a developmental stage with both active cell divisions and dynamic developmental gene expression programs. Since lin-54 null animals are sterile, embryos were obtained from a strain carrying the partial loss-of-function allele lin-54(n2990). Germlines were dissected from lin-54(n3423) null adults that lack detectable transcript and protein. The results revealed conserved roles for DRM in regulating genes involved in cell division, development, and reproduction. We find LIN-54 promotes expression of reproduction genes in the germline, but prevents ectopic activation of germline-specific genes in embryonic soma. Strikingly, genomics and cytological analyses show that DRM binding, a DRM binding motif, and LIN-54-regulated genes are all autosome-enriched. One paradoxical exception occurs the germline, where DRM binds autosomes but genes down-regulated in DRM mutants are enriched on X chromosomes. We compared embryonic or germline gene expression profile of lin-54 mutants with that of wild-type N2 C. elegans. Embryos were obtained from a strain carrying the partial loss-of-function allele lin-54(n2990) grown at 25C for one generation. Germlines were isolated from lin-54(n3423) null adults that lack detectable lin-54 transcript and protein. We isolated the germline region from the tip until late pachytene stage of meiosis, because nuclei in this region are morphologically similar between wild-type and mutant and are all undergoing X chromosome silencing. 3 biological replicates of each genotype/tissue were examined.

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Transcriptomic response of zebrafish embryos to Polyamidoamine (PAMAM) dendrimers

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