Multiple stressors and short term effects on Atlantic salmon (Salmo salar)
The individual and combined molecular acute stress responses of depleted uranium and ionizing radiation was tested in a series of short-term studies with juvenile salmon (Salmon salar) by use of microarrays and quantitative rtPCR. The results showed that depleted uranium and gamma radiation resulted in unique molecular changes which could be characterized by gene expression profiles. The combined effect of these stressors appeared to be quite different from the contribution from each single stressor. In some cases, depleted uranium affected the response of ionizing radiation whereas in other cases the ionizing radiation affected the response of depleted uranium. In a few cases responses that could not be ascribed to the effect of the single stressors was observed, which suggest that potentiation of single responses by exposure to other stressors were observed. The work, which is supposed to be finished autumn 2013, is a collaboration between the MixTox project and a PhD project on multiple stressors (PhD student You Song) at the department of Plant and Environmental Sciences, University of Life Sciences (UMB).
Combined effects of cytotoxic compounds on primary hepatocytes
The combined effects of up to 6 naphthenic acids were tested in a primary culture of rainbow trout hepatocytes using metabolic activity and membrane integrity as markers for cytotoxic effects. The additivity expectations were calculated by the concentration addition (CA) and independent action (IA) prediction models. The naphthenic acids acted in an additive manner at the whole concentration range tested and the observed effects were closer to the CA than the IA model. The work has been published in Environmental Science and Technology.
Combined effects of estrogenic compounds on transgenic zebrafish embryos
The combined effects of estrogenic chemicals were tested in transgenic (cyp19a1b-GFP) zebrafish embryo and primary cultures of rainbow trout hepatocytes to determine if the transgenic zebrafish embryo assay is suitable for screening of combined effects of estrogenic compounds. The effects of the estrogenic mixtures on the zebrafish embryos were mainly additive and were well estimated by both the concentration addition (CA) and independent action (IA) prediction models. Lower than additive effects were only observed for one mixture and only at the highest tested mixture concentrations. One of the mixtures was also tested in a primary hepatocyte culture, using the in vitro production of vitellogenin as biomarker for estrogenic effects. The effect of the non-toxic concentrations was well predicted by CA and IA in both assays. Overall, a similar response was observed in the two models despite different cellular contexts, and it appears that transgenic zebrafish embryos and rainbow trout hepatocytes are suitable model systems for studying the combined effects of estrogenic compounds. The work has been published in Aquatic toxicology. Not available online as of yet.
Combined effects of organic contaminants on Skeletonema costatum
The combined effect of relevant environmental contaminants emitted to coastal waters (pharmaceuticals and personal care products (PPCPs), biocides, polyaromatic hydrocarbon (PAH) and alkylphenol) was tested on the growth of the marine algae S. costatum. Six binary mixtures were tested and were all found to have additive effects on the growth of S. costatum as the observed results were well estimated by CA and IA. The observed effects of a mixture of eight compounds containing PPCPs, biocides, PAH and alkylphenol were positioned between the additivity expectations for CA and IA, and indicate that the combined effects of PPCPs and other relevant pollutants act additive on S. costatum. PPCPs will contribute to the chemical load and increase the risk of biologic effects in areas contaminated with other organic pollutants like antifoulants, PAHs and alkylphenols. Not available online as of yet.
Combined effects of estrogen agonists in a primary culture of rainbow trout hepatocytes
The combined effect of up to 7 estrogen receptor (ER) agonists were tested in a primary culture of rainbow trout hetpatocytes using induction of ER-mediated production of vitellogenin (Vtg) as a biomarker for estrogenicity. The ER agonists acted in an additive manner at low and intermediate total mixture concentrations and less than additive at high total mixture concentrations in primary cultures of rainbow trout hepatocytes. The prediction models CA and IA provided good estimates for the combined effect of the mixtures at low to intermediate total mixture concentrations. The work has been published in Aquatic Toxicology.
Combined effects of oestrogen receptor antagonists on in vitro vitellogenesis
The combined effect of up to 11 estrogen receptor (ER) antagonists were tested in a primary culture of rainbow trout hetpatocytes using reduction of ER-mediated production of vitellogenin (Vtg) as a biomarker for antiestrogenicity. Estrogen receptor antagonists with similar mode of action were found to act additive and the effect could be estimated by the prediction models CA and/or IA. Mixtures of ER antagonists with different and/or unidentified modes of action had stronger reduction potential on the Vtg production than predicted by CA and IA. The work has been published in Aquatic Toxicology.
You Song PhD Thesis
You Song's PhD Thesis Supplemental documents can be found here.