Opin vísindiOpinvisindi.is er stafrænt varðveislusafn fyrir vísindagreinar.https://opinvisindi.is:4432024-03-19T06:23:12Z2024-03-19T06:23:12ZTemporal and intra-thallus variation in arsenic species in the brown macroalga Laminaria digitataSim, RebeccaFeldmann, JoergStengel, Dagmar B.Pétursdóttir, Ásta H.https://hdl.handle.net/20.500.11815/47692024-03-18T11:23:51Z2023-01-01T00:00:00ZTemporal and intra-thallus variation in arsenic species in the brown macroalga Laminaria digitata
Sim, Rebecca; Feldmann, Joerg; Stengel, Dagmar B.; Pétursdóttir, Ásta H.
Environmental context. Arsenic contamination has a disproportionate effect on marine ecosystems. Organisms such as some marine macroalgae, which accumulate potentially toxic elements from the surrounding environment, have developed an internal conversion process that is not yet fully understood. Are arsenic-containing sugars a product of detoxification, or simply the result of phospholipid degradation?
Rationale. Arsenosugars (AsSugar) account for the majority of total arsenic in common seaweed species, yet it is unclear whether these are formed through some detoxification pathway for inorganic arsenic or are precursors/degradation products of arsenic-containing phospholipids in the cell wall.
Methodology. Temporal and intra-thallus variations in water-soluble arsenic were measured by HPLC-ICP-MS, as well as total non-polar and polar arsenic-containing lipids by ICP-MS in Laminaria digitata to offer potential insight into the origins of arsenosugars. Water-soluble speciation with and without freeze-drying were also compared to determine whether freeze-drying changes the water-soluble As speciation.
Results. In general, lower levels of total As were detected in the samples collected in May (39.2–74.5 mg kg−1) compared to those collected in February (72.6–151 mg kg−1). The concentration of arsenate was found to consistently increase along the thallus from the holdfast/stipe (0.78–1.82 mg kg−1) to the decaying fronds (44.4–61.0 mg kg−1) in both months, and AsSug-SO3 was the dominant AsSugar in the majority of samples. The extraction efficiency was lower in fresh samples (64–77%) than in freeze-dried (95–116%) from the same month. Water-soluble, polar AsLipids, and residual As concentrations, were generally highest in February, and the non-polar AsLipids accounted for <0.42% of totAs in all samples.
Discussion. Our results suggest that the arsenosugars are not a product of arsenic detoxification, but a by-product of normal biological activity. It is probable that the arsenosugars are bound to the cell membrane within the Laminaria digitata cells, and lyophilisation is required to release them quantitatively. Future research should focus on speciation of polar lipid-soluble As extracted from fresh samples to determine if the lower extraction efficiency observed in this study is due to the As being in an unextractable form, i.e. lipids, and thus is not removed from cells during water-based extractions.
2023-01-01T00:00:00ZNeurobehavioral Impairment Scale of the A-ONE J: Rasch Analysis and Concurrent ValidationHigashi, YasuhiroTakabatake, ShinichiMatsubara, AsakoNishikawa, KojiKaneda, ToshikatsuNakaoka, KazuyoSomei, YutaÁrnadóttir, Guðrúnhttps://hdl.handle.net/20.500.11815/47682024-03-16T01:04:28Z2023-01-31T00:00:00ZNeurobehavioral Impairment Scale of the A-ONE J: Rasch Analysis and Concurrent Validation
Higashi, Yasuhiro; Takabatake, Shinichi; Matsubara, Asako; Nishikawa, Koji; Kaneda, Toshikatsu; Nakaoka, Kazuyo; Somei, Yuta; Árnadóttir, Guðrún
Background: The ADL-focused Occupation-based Neurobehavioral Evaluation (A-ONE) is used to evaluate both performance of ADL tasks and neurobehavioral impairments (NBIs) that interfere with ADL performance of clients with neurological disorders. Its Japanese translation is referred to as A-ONE J. This study examined the psychometric properties of the Neurobehavioral Impairment (NB) Scale of A-ONE J for persons with cerebral vascular accident (CVA). Methods: Rasch analysis was performed on NB scale data from 185 participants with CVA, as well as from right CVA (RCVA) and left CVA (LCVA) data separately. The values of the obtained Rasch indicators were compared with results from previous A-ONE studies. Results: Unidimensionality was obtained for 55 item CVA scale for the entire group as well as for 55 item RCVA scale and 53 item LCVA scale. Separation reliability for item and person calibrations was high for all three scales. Most comparisons of Rasch indicators concurrently met set criteria. Conclusion: The psychometric properties of the NB scale of A-ONE J were determined. The obtained unidimensionality of the NB scale items for Japanese people with CVA provides an opportunity for quantitative measurement of a wide range of NBIs interfering with their ADL performance.
2023-01-31T00:00:00ZVoluntary corporate social responsibility reporting and assurance practices among United Nations Global Compact member companiesSigurðsson, KjartanWójcik-Jurkiewicz, MagdalenaZieniuk, Pawełhttps://hdl.handle.net/20.500.11815/47672024-03-15T01:04:13Z2023-01-01T00:00:00ZVoluntary corporate social responsibility reporting and assurance practices among United Nations Global Compact member companies
Sigurðsson, Kjartan; Wójcik-Jurkiewicz, Magdalena; Zieniuk, Paweł
Objective: The research aimed to identify practices applied by European companies regarding corporate social responsibility reporting and their relationship with the membership of companies in the United Nations Global Compact (UNGC) international organization. Research Design & Methods: In total, the research sample consisted of 935 companies from 34 European countries. To evaluate the statistical significance of the relationship between the selected variables, we used quantitative methods, including the Pearson chi-square test. Findings: On a large research sample, our research confirmed the impact of membership in the UNGC on non-financial reporting practices, such as: preparing integrated reports, reporting on sustainable development goals (SDGs), using the Organisation for Economic Cooperation and Development (OECD) guidelines for multinational enterprises, International Organization for Standardization (ISO) 26000 corporate social responsibility guidelines, and decisions on external assurance of sustainability reporting. Implications & Recommendations: Conducted research has practical implications. Because the UNGC is an important factor in regard to social change towards corporate social responsibility (CSR) reporting practices, it requires further promotion in European Union (EU) member states. New company membership in UNGC can contribute to the development of CSR reporting. Contribution & Value Added: The article contributes to the literature on sustainability reporting because it provides new insights into the CSR reporting practices by public interest entities located in the EU countries.
2023-01-01T00:00:00ZPINK1 regulated mitophagy is evident in skeletal musclesSingh, FrancoisWilhelm, LeaPrescott, Alan R.Ostacolo, KevinZhao, Jin-FengOgmundsdottir, Margret H.Ganley, Ian G.https://hdl.handle.net/20.500.11815/47662024-03-14T15:11:29Z2024-03-11T00:00:00ZPINK1 regulated mitophagy is evident in skeletal muscles
Singh, Francois; Wilhelm, Lea; Prescott, Alan R.; Ostacolo, Kevin; Zhao, Jin-Feng; Ogmundsdottir, Margret H.; Ganley, Ian G.
PINK1, mutated in familial forms of Parkinson’s disease, initiates mitophagy following mitochondrial depolarization. However, it is difficult to monitor this pathway physiologically in mice as loss of PINK1 does not alter basal mitophagy levels in most tissues. To further characterize this pathway in vivo, we used mito-QC mice in which loss of PINK1 was combined with the mitochondrial-associated POLGD257A mutation. We focused on skeletal muscle as gene expression data indicates that this tissue has the highest PINK1 levels. We found that loss of PINK1 in oxidative hindlimb muscle significantly reduced mitophagy. Of interest, the presence of the POLGD257A mutation, while having a minor effect in most tissues, restored levels of muscle mitophagy caused by the loss of PINK1. Although our observations highlight that multiple mitophagy pathways operate within a single tissue, we identify skeletal muscle as a tissue of choice for the study of PINK1-dependant mitophagy under basal conditions.
2024-03-11T00:00:00Z