Project description:The application of chemical dispersants during marine oil spills can affect the community composition and activity of native marine microorganisms. Several studies have indicated that certain marine hydrocarbon-degrading bacteria, such as Marinobacter spp., can be inhibited by chemical dispersants, resulting in lower abundances and/or reduced hydrocarbon-biodegradation rates. In this respect, a major knowledge gap exists in understanding the mechanisms underlying these observed physiological effects. Here, we performed comparative proteomics of the Deepwater Horizon isolate Marinobacter sp. TT1 grown under different conditions that varied regarding the supplied carbon sources (pyruvate vs. n-hexadecane) and whether or not dispersant (Corexit EC9500A) was added, or that contained crude oil in the form of a water-accommodated fraction (WAF) or chemically-enhanced WAF (CEWAF). We characterized the proteins associated with alkane metabolism and alginate biosynthesis in strain TT1, report on its potential for aromatic hydrocarbon biodegradation and present a proposed metabolism of Corexit components as carbon substrates for the strain. Our findings implicate Corexit in affecting hydrocarbon metabolism, chemotactic motility, biofilm formation, and inducing solvent tolerance mechanisms like efflux pumps in strain TT1. This study provides novel insights into dispersant impacts on microbial hydrocarbon degraders that should be taken into consideration for future oil spill response actions.
Project description:Polycyclic aromatic hydrocarbons are common pollutants in soil, have negative effects on soil ecosystems, and are potentially carcinogenic. The Springtail (Collembola) Folsomia candida is often used as an indicator species for soil toxicity. Here we report a toxicogenomic study that translates the ecological effects of the polycyclic aromatic hydrocarbon phenanthrene in soil to the early transcriptomic responses in Folsomia candida. Microarrays were used to examine two different exposure concentrations of phenanthrene, namely the EC10 (24.95 mg kg-1 soil) and EC50 (45.80 mg kg-1 soil) on reproduction of this springtail, which evoked 405 and 251 differentially expressed transcripts, respectively. Fifty transcripts were differential in response to either concentration. Many transcripts encoding xenobiotic detoxification and biotransformation enzymes (phases I, II, and III) were upregulated in response to either concentration. Furthermore, indications of general and oxidative stress were found in response to phenanthrene. Chitin metabolism appeared to be disrupted particularly at the low concentration, and protein translation appeared suppressed at the high concentration of phenanthrene; most likely in order to reallocate energy budgets for the detoxification process. Finally, an immune response was evoked especially in response to the high effect concentration, which was also described in a previous transcriptomic study using the same effect concentration (EC50) of cadmium. Our study provides new insights in the molecular mode of action of the important polluting class of polycyclic aromatic hydrocarbons in soil animals. Furthermore, we present a fast, sensitive, and specific soil toxicity test which enhances traditional tests and may help to improve current environmental risk assessments and monitoring of potentially polluted sites.
Project description:Animals have developed extensive mechanisms of response to xenobiotic chemical attacks. Although recent genome surveys have suggested a broad conservation of the chemical defensome across metazoans, global gene expression responses to xenobiotics are not known in most invertebrates. Here, using high density tiling arrays with over 2 million probes, we explored genome-wide gene expression in the tunicate Oikopleura dioica in response to two model xenobiotic chemicals – the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP) the pharmaceutical compound Clofibrate (Clo). The genotoxic compound BaP induced xenobiotic biotransformation and oxidative stress responsive genes, as in vertebrates. Notable exceptions were genes of the aryl hydrocarbon receptor (AhR) signaling pathway. Clo also affected the expression of many biotransformation genes and markedly repressed genes involved in energy metabolism and muscle contraction pathways. Oikopleura appears to have basic defensome toolkit consisting of phase I, phase II and phase III biotransformation genes.
Project description:Polycyclic aromatic hydrocarbons are common pollutants in soil, have negative effects on soil ecosystems, and are potentially carcinogenic. The Springtail (Collembola) Folsomia candida is often used as an indicator species for soil toxicity. Here we report a toxicogenomic study that translates the ecological effects of the polycyclic aromatic hydrocarbon phenanthrene in soil to the early transcriptomic responses in Folsomia candida. Microarrays were used to examine two different exposure concentrations of phenanthrene, namely the EC10 (24.95 mg kg-1 soil) and EC50 (45.80 mg kg-1 soil) on reproduction of this springtail, which evoked 405 and 251 differentially expressed transcripts, respectively. Fifty transcripts were differential in response to either concentration. Many transcripts encoding xenobiotic detoxification and biotransformation enzymes (phases I, II, and III) were upregulated in response to either concentration. Furthermore, indications of general and oxidative stress were found in response to phenanthrene. Chitin metabolism appeared to be disrupted particularly at the low concentration, and protein translation appeared suppressed at the high concentration of phenanthrene; most likely in order to reallocate energy budgets for the detoxification process. Finally, an immune response was evoked especially in response to the high effect concentration, which was also described in a previous transcriptomic study using the same effect concentration (EC50) of cadmium. Our study provides new insights in the molecular mode of action of the important polluting class of polycyclic aromatic hydrocarbons in soil animals. Furthermore, we present a fast, sensitive, and specific soil toxicity test which enhances traditional tests and may help to improve current environmental risk assessments and monitoring of potentially polluted sites. Folsomia candida was exposed to phenanthrene spiked soil or untreated (reference/control) soil for 2 days. Two different concentrations of phenanthrene were used, 24.95 and 45.80 mg/kg soil which represent the EC10 and EC50 on reproduction, respectively. For each concentration treatment 4 biological replicates were used, replicate samples consisted of total RNA extracted from ~30 animals exposed in the same jar to either reference or phenanthrene spiked soil. Phenanthrene treated samples were always hybridized to reference samples in an evenly distributed dye-swap manner, which resulted in total in 8 hybridizations of 16 samples.
Project description:Inhibitors directed towards PARP1 and PARP2 are approved agents for the treatment of BRCA-related cancers. Other members of the PARP family have also been implicated in cancer and are being assessed as therapeutic targets in cancer and other diseases. In fact, an inhibitor of PARP7 (RBN-2397) has now reached early-stage human clinical trials. Here, we performed a genome-wide CRISPR screen for genes that modify the response of cells to RBN-2397. We identify the polycyclic aromatic hydrocarbon receptor AHR and multiple components of the cohesin complex as determinants of resistance to this agent. Activators and inhibitors of AHR modulate the cellular response to PARP7 inhibition, suggesting potential combination therapy approaches.
Project description:The opportunistic pathogen Streptococcus gallolyticus is one of the few intestinal bacteria that has been consistently linked to colorectal cancer (CRC). This study aimed to identify S. gallolyticus-induced pathways that could on the long-term add to CRC progression. Transcription profiling of S. gallolyticus-exposed CRC-cells revealed the persistent induction of enzymes involved in biotransformation pathways. Specifically, a diffusible factor of S. gallolyticus (SGF-X) interacts with the aryl hydrocarbon receptor thereby inducing CYP1 enzymes that catalyze the bioactivation of polycyclic aromatic hydrocarbons (PAHs) into toxic intermediates. Importantly, priming CRC-cells with SGF-X containing medium increased the DNA damaging effect of the PAH 3-methylcholanthrene, which was not observed for other intestinal bacteria. In conclusion, this study shows for the first time that bacteria can modulate the biotransformation capacity of CRC-cells that offers a novel theory for a contributing role of S. gallolyticus in the etiology of sporadic CRC. Key words : Colorectal cancer cells, Streptococcus bovis, streptococcus gallolyticus, host-pathogen interactions, Cytochrome P4501A1, DNA-damage, polycyclic aromatic hydrocarbons
Project description:Background: A structurally diverse group of chemicals, including polycyclic aromatic hydrocarbons (PAHs), can inappropriately activate the aryl hydrocarbon receptor (AHR) and lead to adverse health effects. In the zebrafish model, repression of sox9b has a causal role in several AHR-mediated toxic responses, including craniofacial cartilage malformations; however, the mechanism of sox9b repression remains unknown. We previously identified a long non-coding RNA, slincR, which is increased (in an AHR-dependent manner) by multiple AHR ligands and is required for the AHR-activated repression of sox9b. Objective: Enhance our understanding of the signaling events downstream of AHR activation that contribute to toxic responses. To understand slincR’s role in the TCDD-induced toxicity pathway, we performed RNA-sequencing and gene ontology enrichment analysis on 48 hpf control and slincR morphants exposed to 0.1% DMSO or 1 ng/mL TCDD.