Selenium Requirements and Metabolism in Poultry

As counteract against deficiency in livestock, dietary treatments are supplemented with selenium (Se), usually as the inorganic form sodium selenite (SS). Since Se is considered as toxic as well as an essential element, SS is added to prevent an increase of Se in edible chicken parts. However, in many countries, populations suffer from suboptimal Se intake and even Se deficiency, by increasing the use of organic Se sources such as Se‐enriched yeast or wheat in animal feed, there will be a subsequent increase in meat and egg products for human consumption. One could argue that the chickens do not need the extra pool of Se in muscles, as the inorganic form will be sufficient to meet the chickens Se requirements. Since the feed is fortified with selenite, the chickens will always have adequate access to the essential trace element. However, global gene set functional enrichment analysis revealed statistically significant enrichment of a number of biological processes that were dependent on the Se feed sources, such as cell growth, organ development and protein metabolism in favour of organic Se

Limited access to oxygen reduces the release of harmful trace elements from submerged alum shale debris

publishedVersio

Mobile trace elements in sediments from lakes Hawassa, Koka, and Ziway in the Ethiopian Rift Valley

acceptedVersio

Deciphering the combined effects of environmental stressors on gene transcription : a conceptual approach

The use of classical mixture toxicity models to predict the combined effects of environmental stressors based on toxicogenomics (OMICS) data is still in its infancy. Although several studies have made attempts to implement mixture modeling in OMICS analysis to understand the low dose interactions of stressors, it is not clear how interactions occur at the molecular level and how results generated from such approaches can be better used to inform future studies and cumulative hazard assessment of multiple stressors. The present work was therefore conducted to propose a conceptual approach for combined effect assessment using global gene expression data, as illustrated by a case study on assessment of combined effects of gamma radiation and depleted uranium (DU) on Atlantic salmon (Salmo salar). Implementation of the independent action (IA) model in reanalysis of a previously published microarray gene expression dataset was performed to describe gene expression patterns of combined effects and identify key gene sets and pathways that were relevant for understanding the interactive effects of these stressors. By using this approach, 3120 differentially expressed genes (DEGs) were found to display additive effects, whereas 279 (273 synergistic, 6 antagonistic) were found to deviate from additivity. Functional analysis further revealed that multiple toxicity pathways, such as oxidative stress responses, cell cycle regulation, lipid metabolism, and immune responses were enriched by DEGs showing synergistic gene expression. A key toxicity pathway of DNA damage leading to enhanced tumorigenesis signaling is highlighted and discussed in detail as an example of how to take advantage of the approach. Furthermore, a conceptual workflow describing the integration of combined effect modeling, OMICS analysis, and bioinformatics is proposed. The present study presents a conceptual framework for utilizing OMICS data in combined effect assessment and may provide novel strategies for dealing with data analysis and interpretation of molecular responses of multiple stressors

Modeling key processes affecting Al speciation and transport in estuaries

Assessments of the impacts of aluminium (Al) to aquatic organisms in estuarine waters have suffered from the lack of available models that can accurately predict the presence of toxic physico-chemical forms (species) of Al at adequate spatial and temporal resolution. In the present work, transport and distribution of river-discharged Al species through changing environmental conditions in the Sandnesfjorden estuary, South-Eastern Norway, was predicted using a numerical model system at relatively high spatial (32 m × 32 m in horizontal) and temporal (1 h) resolution. New model code was implemented, including dynamic, salinity-dependent speciation and transformation processes, based on in situ measurements from several Norwegian estuaries as well as experimental data. This is the first time such elemental speciation code including LMM, colloidal, particle and sediment species is utilized in an estuary case in combination with high resolution hydrodynamics and compared to an extensive observational dataset. Good agreement was obtained between modeled and observed total and fractionated Al concentration at several stations along the fjord transect. Without including background contribution of Al from the coastal water, the model predicted too low Al concentrations (by up to approximately a factor 4) near the fjord mouth. The surface Al concentrations were also underestimated due to overestimated near-surface vertical mixing in the hydrodynamic model. The observed correlation between salinity and total Al concentration was well reproduced by the model in situations with low upper layer volume flux, typical under low river flow conditions. In contrast, the predicted surface salinity and total Al concentration were less correlated under high-flux conditions. As the general trends of Al concentrations and speciation were well reproduced, this study demonstrated that by including carefully chosen transfer rates, the model can be used to predict spatio-temporal distribution of total contamination as well as concentration levels of the elemental species.publishedVersio

Bruk av silikat som alternativ til kalking - feltforsøk med flytende og fast silikat i 1997

Feltforsøk med dosering av flytende silikat-lut som et alternativ til kalking har tidligere vært utprøvd i Tangedalselva. Med tanke på videre bruk av silikat i naturen var det viktig å få undersøkt hvorvidt dosering av silikat kunne ha uønskede negative sideeffekter på den naturlige fauna og flora i et elvesystem. Prosjektet i Tangedalselva i 1997 hadde derfor som målsetning, i tillegg til de kjemiske studiene, å undersøke effektene av silikatdosering på villfisken i elva (aure), på bunndyrsamfunnet, og på artssammensetning og mengde av påvekstalger. Når det gjelder prosjektet med bruk av fast silikat i Aurtjernbekken i Akershus, hadde det sin bakgrunn i behovet for nye metoder for avsyring av bekkesystemer. Resultatene fra Tangedalselva var lovende, og viste ingen klare negative effekter på noen av organismegruppene som ble undersøkt. Eksponeringsforsøk med den sensitive døgnfluarten Baetis rhodani viste sterkt redusert dødelighet i silikatbehandlet vann. De kjemiske studiene viste at en dose på mellom 0,6 og 2 mg SiO2 pr. liter var nødvendig for å redusere konsentrasjonen av Ali i Tangedalselva. Forsøkene med fast silikat i Aurtjernbekken var mindre lovende, og viste minimale effekter av utlegging av fast silikat både på aluminiumskjemien og på aure eksponert i bur. Lav løselighet på silikatklumpene er den sannsynlige årsaken til dett