Project description:The aim of this study was to identify TBBPA-degrading organisms in a complex microbial community by a metagenome-based functional metaproteomic approach, using protein-based stable isotope probing (protein-SIP). Firstly, the degradation kinetics were evaluated in order to simulate the decrease of residual mass of the labelled compound based on experimental data. In sequence, a metagenome was generated, and biomass was collected in different time-points for protein-SIP in incubations with 13C-TBBPA. This approach allowed for the identification organisms assimilating labelled carbon from the cometabolic degradation of a micropollutant.
Project description:3,3’,5.5’-Tetrabromobisphenol A (TBBPA) is a widely used brominated flame-retardant utilized in the production of electronic devices and plastic paints. The objective of this study is to use zebrafish as a model and determine the effects of TBBPA exposure on early embryogenesis. We initiated TBBPA exposures (0, 10, 20 and 40μM) at 0.75 h post fertilization (hpf) and monitored early developmental events such as cleavage, blastula and epiboly that encompass maternal-to-zygotic transition (MZT) and zygotic genome activation (ZGA). Our data revealed that TBBPA exposures induced onset of developmental delays by 3 hpf (blastula). By 5.5 hpf (epiboly), TBBPA-exposed (10-20 μM) embryos showed concentration-dependent developmental lag by up to 3 stages or 100% mortality at 40 μM. Interestingly, while continued 0.75- 48 hpf TBBPA exposures (10 μM) led to severely deformed embryos, replacing exposure solution with chemical-free media at 6 hpf mitigated this effect, with 100% normal embryos at 48 hpf. To examine the genetic basis of TBBPA-induced delays, we conducted mRNA-sequencing on embryos exposed to 0 or 40 μM TBBPA from 0.75 hpf to 2, 3.5 or 4.5 hpf. Read count data showed that while TBBPA exposures had no overall impacts on maternal or maternal-zygotic genes, collective read counts for zygotically activated genes were lower in TBBPA treatment at 4.5 hpf compared to time-matched controls, suggesting that TBBPA delays ZGA. Gene ontology assessments for both time- and stage-matched differentially expressed genes revealed TBBPA-induced inhibition of chromatin assembly- a process regulated by histone modifications. Since acetylation is the primary histone modification system operant during early ZGA, we hypothesized that TBBPA inhibits histone acetylation, resulting in lack of open chromatin within promoters of zygotic genes and delaying ZGA. Therefore, we co-exposed embryos to 20 μM TBBPA and 100 μM N-(4-Chloro-3-(trifluoromethyl)phenyl)-2-ethoxybenzamide (CTB) -a histone acetyltransferase activator that promotes histone acetylation- and showed that TBBPA-CTB co-exposures from 0.75- 3 hpf significantly reversed TBBPA-only developmental delays, suggesting that TBBPA-induced phenotypes are indeed driven by repression of histone acetylation. Collectively, our work demonstrates that TBBPA disrupts ZGA and early developmental morphology, potentially by inhibiting histone acetylation. Future studies will focus on mechanisms of TBBPA-induced chromatin modifications.
Project description:Vertebrate eye devlopment is partially regulated by thyroid hormones. TBBPA is a chemical that interacts with thyroid receptors. We investigated the effects of TBBPA on eye development of zebrafish. We expected TBBPA exposure to cause transcriptional changes of visual-system-related genes, which find their phenotypic anchoring in eye malformations and dysfunction, as observed in our previous studies. Additionally, the reversibility of effects after recovery in clean water for three days was investigated.
Project description:To identify liver transcripts differentially expressed due to treatment with tetrabromobisphenol A-bis(2,3-dibromopropyl ether) (TBBPA-DBPE), we collected RNA from male Harlan Sprague Dawley rats exposed to 0, 0.1, 0.94, 9.4, 94.3 or 943 mg/kg TBBPA.DBPE, 5 days after exposure for animals 7 weeks of age. These samples were interrogated with the Affymetrix Rat Genome 230 2.0 GeneChip array. A total of 0,0,0,0,0, and 0 gene transcripts were differentially expressed due to TBBPA.DBPE treatment after exposure to 0.1, 0.94, 9.4, 94.3 or 943 mg/kg TBBPA.DBPE (false discovery rate (FDR) < 0.05).
Project description:Study purpose: to explore the entire spectrum of proteomic and genomic changes (amongst others) involved in diseases and in healthy/control populations. The Study is designed to discover biomarkers, develop and validate diagnostic assays, instruments and therapeutics as well as other medical research. Specifically, researchers may analyze proteins, RNA, DNA copy number changes, including large and small (1,000-100,000 kb) scale rearrangements, transcription profiles, epigenetic modifications, sequence variation, and sequence in both diseased tissue and case-matched germline DNA from Subjects.
Project description:AT rich interactive domain 1A (ARID1A) is one of the most commonly mutated genes in a broad variety of tumors. The mechanisms that involve ARID1A in ampullary cancer progression remains elusive. Here, we evaluated the frequency of ARID1A and KRAS mutations in ampullary adenomas and adenocarcinomas and in duodenal adenocarcinomas from two cohorts of patients from Singapore and Romania, correlated with clinical and pathological tumor features, and assessed the functional role of ARID1A. In the ampullary adenocarcinomas, the frequency of KRAS and ARID1A mutations was 34.7% and 8.2% respectively, with a loss or reduction of ARID1A protein in 17.2% of the cases. ARID1A mutational status was significantly correlated with ARID1A protein expression level (P=0.023). There was a significant difference in frequency of ARID1A mutation between Romania and Singapore (2.7% versus 25%, P=0.04), suggestive of different etiologies. One somatic mutation was detected in the ampullary adenoma group. In vitro studies indicated the tumor suppressive role of ARID1A. Our results warrant further investigation of this chromatin remodeller as a potential early biomarker of the disease, as well as identification of therapeutic targets in ARID1A mutated ampullary cancers.
Project description:Clostridium difficile, a major cause of antibiotic-associated diarrhea, produces highly resistant spores that contaminate hospital environments and facilitate efficient disease transmission. We purified C. difficile spores using a novel method and show that they exhibit significant resistance to harsh physical or chemical treatments and are also highly infectious, with <7 environmental spores per cm(2) reproducibly establishing a persistent infection in exposed mice. Mass spectrometric analysis identified approximately 336 spore-associated polypeptides, with a significant proportion linked to translation, sporulation/germination, and protein stabilization/degradation. In addition, proteins from several distinct metabolic pathways associated with energy production were identified. Comparison of the C. difficile spore proteome to those of other clostridial species defined 88 proteins as the clostridial spore "core" and 29 proteins as C. difficile spore specific, including proteins that could contribute to spore-host interactions. Thus, our results provide the first molecular definition of C. difficile spores, opening up new opportunities for the development of diagnostic and therapeutic approaches.