Project description:Contaminated aquifer (Dusseldorf-Flinger, Germany) templates extracted from 5 sediment depths ranging between 6.4 and 8.4 m below ground and over 3 years of sampling were amplified for amplicon pyrosequencing using the primers Ba27f (5’-aga gtt tga tcm tgg ctc ag-3’) and Ba519r (5’- tat tac cgc ggc kgc tg-3’), extended as amplicon fusion primers with respective primer A or B adapters, key sequence and multiplex identifiers (MID) as recommended by 454/Roche. Amplicons were purified and pooled as specified by the manufacturer. Emulsion PCR (emPCR), purification of DNA-enriched beads and sequencing run were performed following protocols and using a 2nd generation pyrosequencer (454 GS FLX Titanium, Roche) as recommended by the developer. Quality filtering of the pyrosequencing reads was performed using the automatic amplicon pipeline of the GS Run Processor (Roche), with a slight modification concerning the valley filter (vfScanAllFlows false instead of TiOnly) to extract the sequences. Demultiplexed raw reads were furhter trimmed for quality and lenght (>250 bp).
Project description:Contaminated aquifer (Dusseldorf-Flinger, Germany) templates extracted from 5 sediment depths ranging between 6.4 and 8.4 m below ground and over 3 years of sampling were amplified for amplicon pyrosequencing using the primers Ba27f (5’-aga gtt tga tcm tgg ctc ag-3’) and Ba519r (5’- tat tac cgc ggc kgc tg-3’), extended as amplicon fusion primers with respective primer A or B adapters, key sequence and multiplex identifiers (MID) as recommended by 454/Roche. Amplicons were purified and pooled as specified by the manufacturer. Emulsion PCR (emPCR), purification of DNA-enriched beads and sequencing run were performed following protocols and using a 2nd generation pyrosequencer (454 GS FLX Titanium, Roche) as recommended by the developer. Quality filtering of the pyrosequencing reads was performed using the automatic amplicon pipeline of the GS Run Processor (Roche), with a slight modification concerning the valley filter (vfScanAllFlows false instead of TiOnly) to extract the sequences. Demultiplexed raw reads were furhter trimmed for quality and lenght (>250 bp). 15 samples examined in total from important plume zones of the aquifer sampled in Feb. 2006, Sep. 2008 and Jun. 2009 (5 every year of sampling).
Project description:The zebrafish embryo has repeatedly proved to be a useful model for the analysis of effects by environmental toxicants. This study was performed to investigate if an approach combining mechanism-specific bioassays with microarray techniques can obtain more in-depth insights into the ecotoxicity of complex pollutant mixtures as present, e.g., in freeze-dried whole sediment samples and their corresponding organic extracts in parallel. To this end, altered gene expression was compared to data from established bioassays as well as to results from chemical analysis. Microarray analysis revealed several classes of significantly regulated genes which could to a considerable extent be related to the hazard potential. Results indicate that potential classes of contaminants can be assigned to sediment extracts by both classical biomarker genes and corresponding expression profile analyses of known substances. However, it is difficult to distinguish between specific responses and more universal detoxification of the organism. Additionally, different gene expression was shown to be less influenced by the sampling site than by the method of exposure, which could be attributed to differential bioavailability of contaminants. Microarray analyses were performed with early life stages of zebrafish exposed to sediment extracts or freeze-dried sediment from three sampling sites (Ehingen, Lauchert, Sigmaringen) along the Upper part of the Danube River, Germany. The expression profiles were compared within the sampling sites, between the exposure scheme and to the expression pattern of model toxicants, such as 4-chloroaniline, Cadmium, DDT, TCDD, and Valproic acid (Gene Expression Omnibus Series GSE9357). Additionally, mechanism-specific bioassays and chemical analysis of the sediments have been combined and compared to the present gene expression data.
Project description:The zebrafish embryo has repeatedly proved to be a useful model for the analysis of effects by environmental toxicants. This study was performed to investigate if an approach combining mechanism-specific bioassays with microarray techniques can obtain more in-depth insights into the ecotoxicity of complex pollutant mixtures as present, e.g., in freeze-dried whole sediment samples and their corresponding organic extracts in parallel. To this end, altered gene expression was compared to data from established bioassays as well as to results from chemical analysis. Microarray analysis revealed several classes of significantly regulated genes which could to a considerable extent be related to the hazard potential. Results indicate that potential classes of contaminants can be assigned to sediment extracts by both classical biomarker genes and corresponding expression profile analyses of known substances. However, it is difficult to distinguish between specific responses and more universal detoxification of the organism. Additionally, different gene expression was shown to be less influenced by the sampling site than by the method of exposure, which could be attributed to differential bioavailability of contaminants.