| 41. |
- Mahaffy, Peter G., et al.
(författare)
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Can Chemistry Be a Central Science without Systems Thinking?
- 2019
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Ingår i: Journal of Chemical Education. - : American Chemical Society (ACS). - 0021-9584 .- 1938-1328. ; 96:12, s. 2679-2681
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- What is the history and justification of the claim that chemistry is "the central science"? Are our students able to see and appreciate such centrality of the knowledge of chemistry in the curriculum as well as in its broader interconnections with other fields of study and with societal issues? In this editorial for the special issue Reimagining Chemistry Education: Systems Thinking, and Green and Sustainable Chemistry, we, as guest editors, highlight the case made in the collective contributions to the special issue that systems thinking, including green and sustainable chemistry, shows promise as an approach to help chemistry students zoom out from detailed and fragmented disciplinary content to obtain a more holistic view of chemistry and its integral connection to earth and societal systems. Indeed, we ask the following question: How can we as a community of chemists and chemistry educators live up to the claim of being practitioners of the central science if we do not equip our students to engage in systems thinking? We further invite the community to make use of and build upon the contributions in this special issue and participate in a paradigm change in chemistry education that will help prepare our students to be citizens and scientists who are better equipped to deal with the grand challenges in the world.
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| 42. |
- Ribbenstedt, Anton, 1986-, et al.
(författare)
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Toxicometabolomics and biotransformation in single zebrafish embryos exposed to carbamazepine
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We report here on the high throughput determination of biotransformation products(bioTPs) and toxicometabolomics in single zebrafish (ZF) embryos exposed to carbamazepine(CBZ). Exposures were carried out in 96-well plates with six CBZ concentrations ranging from 0.5 μg/L to 50 mg/L (n=12 embryos/dose). In the 50 mg/L dose group 33% of the embryos developed edema during the exposure (120hpf) while hatching was significantly delayed in three of the lower dose groups (0.46, 3.85 and the 445 μg/L) compared to the control at 48 hpf. Toxicometabolomic analysis together with random forest modelling revealed a total of 80 significantly affected metabolites (22 identified via targeted lipidomics and 58 via non-target analysis). The wide range of doses tested enabled observation of both monotonic and nonmonotonic dose-responses which fit the known mode of action of CBZ. A novel pathway was also proposed based on changes in PE-Cer (d16:2/24:1; CL 2-3) which could be the result of CBZ induced apoptosis via induction of the enzyme SAMD8. In addition, 2 CBZ bioTPs were identified without additional exposure experiments. Overall this work showcases the potential of toxicometabolomics and bioTP determination in single ZF embryos for improved and comprehensive chemical hazard assessment.
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| 43. |
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| 44. |
- Gutensohn, Mareike Franziska, 1992-
(författare)
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Unraveling the importance of thiol compounds on mercury speciation, uptake and transformation by the iron-reducer Geobacter sulfurreducens
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The biogenic methylation of inorganic, divalent mercury (Hg(II)) by methylating microorganisms leads to formation and bioaccumulation of monomethyl mercury (MeHg) in the environment and can cause severe damage to ecosystems and human health. Diverse microorganisms carry the gene sequence hgcAB and are able to methylate Hg(II) intracellularly. The interplay of biological, chemical and physical parameters is driving mercury (Hg) transformation by microorganisms. The chemical speciation of Hg(II) with thiol compounds, both with dissolved low molecular mass (LMM) thiols and thiols present on microbial membrane surfaces, is one key factor for Hg availability and transformation. In this work the role of thiol compounds with respect to Hg speciation, uptake and transformation was studied by the iron-reducing model organisms Geobacter sulfurreducens. The turnover of dissolved thiols and the role of outer and inner membrane thiols was studied with novel experimental strategies.In Paper I and II the formation of thiol compounds was studied under varying nutrient conditions. It was shown that the formation of LMM-thiol compounds was impacted by divalent iron, Fe(II). Furthermore, we showed the turnover of the small LMM-thiol cysteine to the branched LMM-thiol penicillamine, which was further amplified by the addition of exogenous cysteine or nutrients. This turnover of small to branched LMM-thiols impacted the Hg(II) speciation in methylation assays and the relative contribution between cysteine and penicillamine was important for Hg(II) availability, uptake and methylation. In addition, the partition of Hg(II) between the cell-adsorbed and dissolved phase was shifted towards the latter at higher LMM-thiol concentrations. Nutrient concentrations impacted cell physiology due to a shift to an active metabolism and a faster metabolization of LMM-thiols. We concluded that the interplay between thiol metabolism, Hg(II) speciation and cell physiology are key parameters for Hg(II) methylation by G. sulfurreducens. In Paper III The outer and inner membrane was characterized independently by two X-ray absorption spectroscopy techniques. The determination of the Hg speciation by both X-ray absorption spectroscopy techniques showed coherent results for both the outer and inner membrane of G. sulfurreducens. The concentration of thiol membrane groups was higher on the inner compared to the outer membrane. The differences between the outer and inner membrane suggested that thiol concentration and Hg coordination environment likely impact the Hg(II) internalization. The role of membrane thiols for Hg(II) uptake and transformation was further investigated in Paper IV by selectively blocking these functional groups. Partitioning and uptake of Hg was not affected by blocking the outer and inner membrane thiols of whole cell and spheroplast samples, respectively. However, the Hg(II) methylation was decreased by blocking thiols at the outer membrane, but no effect was observed by blocking thiols at the inner membrane. Blocking of membrane surface thiols changed the physiology in whole cells but not in spheroplasts. This result suggested weaknesses of the applied blocking approach. In addition, Hg(II) reduction was studied on the outer and inner membrane and showed the formation of liquid and gaseous elemental Hg, Hg(0), in Paper III and IV, respectively.Overall, this work showed the central role of dissolved and cell-associated thiol compounds for Hg(II) uptake and the transformation reactions. Herby, concentration, compositions and distribution of thiols are crucial and impact the Hg(II) speciation, partitioning, uptake and availability for Hg(II) methylation and reduction. In addition, cell physiology is impacting the methylation potential and the turnover of LMM-thiol compounds. The role of membrane surface thiols for Hg(II) uptake was not fully identified, however such thiols were for the first time characterized selectively for the outer and inner membrane by X-ray absorption spectroscopy.
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| 45. |
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| 46. |
- Bergsten, Carl Johan, 1953, et al.
(författare)
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The Field Study Organs
- 2011
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Ingår i: The Collapse Project: corrosion of organ pipes - causes and recommendations. - Brusels : European Union. - 9789279170799 ; , s. 24-55
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 47. |
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| 48. |
- Martella, Giulia, 1993-
(författare)
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DNA adductomics: Method development and integration in biological effect monitoring
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Environmental omics can provide informative biomarkers for identifying pathologies or physiological responses to environmental change. Nucleic acid adductomics, one of the newest omics techniques, is particularly well suited for assessing exposure and effects of environmental contaminants because the technique can capture modifications at the (epi)genome level. However, identifying potential adduct-biomarkers is challenging, especially in non-model organisms. Therefore, the primary aims of this study were to improve the methodology and explore the applicability of nucleic acid adductomics in environmental monitoring of the biological effects of contaminants, using amphipods as sentinel species.From a methodology perspective, this thesis presents a gradual progression in screening and detecting DNA modifications. The mass spectrometry (MS) based approach for identifying candidate DNA adducts utilized the characteristic neutral loss of deoxyribose. In Paper I, the data generated from high resolution MS in Full Scan-Data independent Acquisition mode were analyzed manually using the fragmentation pattern of nucleoside adduct ions. In Paper II, processing time and efficiency were significantly improved by the development of nLossFinder software. Further, TraceFinder software was combined and used to evaluate and quantify detected adducts (Paper III). Another important development was a simultaneous approach for analysis of both DNA and RNA adducts in a single MS run presented in Paper IV. The analysis of amphipod samples based on the existing approaches and methods developed in this thesis showed that reproductive pathologies identified by the microscopic analysis were associated with specific DNA modifications that can be used to classify field-collected individuals according to their health status (Paper I). Moreover, epigenetic marks were the most influential adducts for this classification. Finally, the adduct profile of amphipods differed between the areas with relatively high and low contamination loads based on PAH and trace metal concentrations in the sediment (Paper III). Also, significant correlations were found between DNA adducts and specific contaminants.These method developments and findings uniquely contribute to the field of environmental omics, providing tools for data processing and demonstrating the applicability of nucleic acid adductomics in environmental health research and biological effect monitoring.
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| 49. |
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| 50. |
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