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Transcriptomic effects of two Forafac® fluorosurfactants in turbot

ABSTRACT: Fluorosurfactants are the key components in aqueous film forming foams (AFFF). They provide these fire fighting agents with the required low surface tension and they enable film formation on top of lighter fuels to prevent burn back. Development of effective and environmentally acceptable PFOS alternatives is one of the most important priorities in the fire fighting foam industry. DuPontTM offers the fluorosurfactant mixtures Forafac®1157 and Forafac®1157N for the formulation of AFFFs which are alternatives to the persistent and toxic perfluorooctane sulphonate (PFOS). Ecotoxicological testing of these inadequately documented mixtures is necessary to include them in AFFF hazard and risk assessment. Juvenile turbot (Scophthalmus maximus) was exposed for 14 days to 0.5 and 1.5 mg/l of the fluorosurfactant mixtures used in Forafac®1157 and Forafac®1157N. In a first transcriptomics experiment, microarray analysis revealed differentially expressed gene transcripts which were mainly involved in digestion and in the immune system. This discovery-driven screening approach offered the basis for new hypotheses that were tested in two subsequent experiments in which food intake, energy reserves, growth and a set of haematological parameters were examined. Additionally, effects of the two mixtures were compared to those of PFOS. Based on the results of this study, the mode of action of Forafac®1157N was the activation of the acute phase reaction resulting in increased leukocyte concentrations and the inhibition of growth due to the high energetic cost of toxicant exposure. For Forafac®1157, evidences of immunosuppression were found on the transcriptional level and the altered differential leukocyte profiles indicated that stress was induced in these fish. However, food intake, energy reserves and growth were not compromised, even at high exposure concentrations, which was in contrast to the effects seen after PFOS exposure. Taking into account that Forafac®1157 appeared to be less toxic than PFOS, this mixture could be considered as a more environmentally acceptable PFOS alternative for the use in AFFFs.

ORGANISM(S): Scophthalmus maximus

PROVIDER: GSE28488 | GEO | 2011/05/22

SECONDARY ACCESSION(S): PRJNA139301

REPOSITORIES: GEO

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Project description:Fluorosurfactants are the key components in aqueous film forming foams (AFFF). They provide these fire fighting agents with the required low surface tension and they enable film formation on top of lighter fuels to prevent burn back. Development of effective and environmentally acceptable PFOS alternatives is one of the most important priorities in the fire fighting foam industry. DuPontTM offers the fluorosurfactant mixtures Forafac®1157 and Forafac®1157N for the formulation of AFFFs which are alternatives to the persistent and toxic perfluorooctane sulphonate (PFOS). Ecotoxicological testing of these inadequately documented mixtures is necessary to include them in AFFF hazard and risk assessment. Juvenile turbot (Scophthalmus maximus) was exposed for 14 days to 0.5 and 1.5 mg/l of the fluorosurfactant mixtures used in Forafac®1157 and Forafac®1157N. In a first transcriptomics experiment, microarray analysis revealed differentially expressed gene transcripts which were mainly involved in digestion and in the immune system. This discovery-driven screening approach offered the basis for new hypotheses that were tested in two subsequent experiments in which food intake, energy reserves, growth and a set of haematological parameters were examined. Additionally, effects of the two mixtures were compared to those of PFOS. Based on the results of this study, the mode of action of Forafac®1157N was the activation of the acute phase reaction resulting in increased leukocyte concentrations and the inhibition of growth due to the high energetic cost of toxicant exposure. For Forafac®1157, evidences of immunosuppression were found on the transcriptional level and the altered differential leukocyte profiles indicated that stress was induced in these fish. However, food intake, energy reserves and growth were not compromised, even at high exposure concentrations, which was in contrast to the effects seen after PFOS exposure. Taking into account that Forafac®1157 appeared to be less toxic than PFOS, this mixture could be considered as a more environmentally acceptable PFOS alternative for the use in AFFFs. Juvenile turbot with a mean weight of 7.21 ± 1.91 g and a mean length of 7.34 ± 0.33 cm were exposed to nominal concentrations of 0 mg/L; 0.5 mg/L and 1.5 mg/L for both Forafac®1157 and Forafac®1157N during 14 days. Three different 45 L aquaria per exposure condition were used resulting in 3 tank replicates. Each replicate aquarium contained six turbot. After decapitation, the liver was dissected, homogenized in liquid nitrogen and stored at -80 °C until further analysis. The liver homogenates of the 6 fish per aquarium of exposure experiment 1 were pooled prior to RNA extraction. After RNA extraction, fluorescently labelled cRNA was constructed with each sample labelled with Cy3 as well as with Cy5.An Agilent custom 15k oligonucleotide microarray (Agilent Technologies) was used to measure gene transcription levels. The microarray platform, constructed by ACUIGEN (University de Santiago de compostela, Spain), contained 4 305 turbot-specific oligonucleotide fragments originating from an immune-related EST turbot database. Two probe volumes (Cy3 vs. Cy5) corresponding with 300 ng cRNA were mixed and applied onto every microarray. The hybridization design comprised one separate n+2 A-optimal design for each of the Forafac® mixtures.

Project description:Perfluorooctane sulfonate (PFOS) has been manufactured for over 50 years in increasing quantities and has been used for several industrial and commercial aims. Due to the persistence and the bioaccumulation of this pollutant, it can be found worldwide in wildlife and humans. Biochemical effects of PFOS exposure are mainly studied in mammalian model species and information about effects on fish species remain largely scarce. This lack of toxicity data points out that there is an urgent need for the mechanistic molecular understanding of the mode of action of this pollutant. In the present study, common carp (Cyprinus carpio) was exposed through water for 14 days at concentrations of 0.1; 0.5 and 1 mg/l PFOS. Liver was selected as target tissue. Custom microarrays were constructed from cDNA libraries obtained with Suppression Subtractive Hybridization-Polymerase chain reaction (SSH-PCR) experiments. Microarray data revealed that the expression of several genes in the liver was influenced by PFOS exposure and real-time PCR was used to confirm these gene expression changes. The affected genes were mainly involved in energy metabolism, reproduction and stress response. Furthermore, the relative condition factor and the hepatosomatic index of the exposed fish were significantly lower after 14 days of exposure as well as the available glycogen reserves. At all levels of biological organization, indications of a trade-off between the metabolic cost of toxicant exposure on one hand and processes vital to the survival of the organism on the other hand were seen. Our results support the prediction that increases in energy expenditure negatively affects processes vital to the survival of an organism, such as growth. Keywords: PFOS, common carp, microarray, condition factor, energy reserves, metabolic cost There were 3 biological replicates for each exposure concentration. For each biological replicate control versus exposed hybridizations were carried out. The mean of the biological replicates was calculated for the differentially expressed genes.

Project description:Purpose: the goal of this project is to study the effects of the PFOS (perfluorooctanesulfonate) in the transcriptome profiling (RNA-seq) of exposed zebrafish larvae. Methods: Total RNA was isolated from the samples using AllPrep DNA/RNA Mini Kit (Qiagen, CA, USA) as described by the manufacturer. Three high quality sample per condition were chosen to the mRNA enrichment using KAPA Stranded mRNA-Seq Kit Illumina® Platforms (Kapa Biosystems). Transcriptomic profiles were generated by deep sequencing using Illumina TruSeq SBS Kit v3-HS (pair-ended; 2x76bp) on a HiSeq2000 sequencing system. Image analysis, base calling and quality scoring of the run were processed using the manufacturer’s software Real Time Analysis (RTA 1.13.48) and followed by generation of FASTQ sequence files by CASAVA. Statistical analysis: RNA-seq reads were aligned to the D. rerio reference genome (GRCz10) using STAR version 2.5.1b . Genes annotated in GRCz10.84 were quantified using RSEM version 1.2.28 with default parameters. Differential expression analysis between all PFOS conditions was performed with the DESeq2 (v.1.10.1) R package with the Likelihood ratio test option. ANOVA-PLS was performed on the normalized data using the lmdme package in R (v. 1.0.136, R Core Team). Results: We generated on average 39 million paired-end reads for each sample and identified aproximatelly 24500 transcripts. 1434 differentially expressed genes (DEGs) were detected which could be divided in 2 clusters including 767 and 667 genes, respectively. Affected metabolic pathways were analyzed from the DEGs: lipid transport and metabolism, protein ubiquination, antigen processing, immune system, apoptosis, trans-membrane, cell matrix, Zn-ion binding, cytokines and JAK-STAT signaling pathways', among others, were down or upregulated. Conclusions: Our results suggest a complex, multiple endocrine disruption-like toxic effects at a concentrations well bellow the 1 mg/L, considered as the LOAEC/NOAEC for many of the macroscopic effects traditionally linked to PFOS toxicity in zebrafish embryos. While our results confirm the known effect of PFOS in lipid metabolism, we found a clear decrease on expression of many genes related to natural immunity and defense against infections. We propose that this transcriptional pattern may be a marker for the immunotoxic effects of PFOS and other related substances in fish and other vertebrates, including humans. We concluded that our analysis allowed us the identification of underlying molecular mechanisms occurring simultaneously at the exposed animals. While this approach is very useful to analyze the effects of compounds, like PFOS, able to interact with different cellular targets, we believe that it can be also applied to the characterization of the different toxic components present in complex natural mixtures.

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Transcriptomic effects of two Forafac® fluorosurfactants in turbot

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