The levels of mercury have shown to increase in the Arctic environment as a cause of human activities. Few studies have examined the antioxidant system as a response to heavy metals in Arctic seabirds. Levels of the elements mercury (Hg), selenium (Se), cadmium (Cd) and zinc (Zn) were analyzed in hepatic tissues of female common eiders (Somateria mollissima) collected in July 2008 and 2009 from Kongsfjorden (KF) and Liefdefjorden (LF), Svalbard. The molar ratio of Hg relative to Se (ratio Hg:Se) was also calculated. The two fjord systems are dominated by inflow of different water masses (Atlantic vs. Arctic), which are suggested to vary in the abundance of contaminants. As an indicator of heavy metal exposure, antioxidants in the defense against reactive oxygen species (ROS) were analyzed. These were total reduced glutathione (tGSH), oxidized glutathione (GSSG) and their ratio (tGSH:GSSG), together with its unique enzymes glutathione reductase (GR) and glutathione peroxidase (GPx). Other proteins quantified included metallothionein (MT) and catalase (CAT). As a measure of oxidative damage the levels of lipid peroxidation (TBARS) were analyzed. Se, ratio Hg:Se, GSSG, ratio tGSH:GSSG, GPx and CAT were found to be significantly different between the locations; however this was only in 2008. No parameter was found significantly different between the fjords in 2009. Differences were mainly thought to be caused by seasonal changes between the locations and years rather than various inflows of Atlantic and Arctic waters in the two fjords. The common eiders seems to be less affected by the examined elements compared to seabirds at higher trophic position, except with respect to Se, which were found in relative high concentrations. In the general linear models (GLM) Hg was a strong predictor of levels of GR and MT. In addition, Se was found to correlate with GPx and Zn correlated strongly with MT. However, the metals revealed fewer relationships with enzyme activity compared to previous studies. The present study suggests that several physiological and ecological factors are more important than element burden in explaining differences in status of the antioxidant defense system. This especially involves the female common eider which goes through a prolonged period of incubation fast.

VBrown trout (Salmo trutta) from Lake Mjøsa, Norway, contain very high levels of polybrominated diphenyl ethers (PBDEs), in addition to elevated levels of other persistent organic pollutants (POPs) and trace metals, including mercury (Hg). By contrast, the levels of Se in brown trout are low. This study investigated whether the plasma thyroid hormone (TH) levels of free-ranging trout in Lake Mjøsa were affected by the various contaminants and oxidative stress. Both plasma thyroxine (T4) and triiodothyronine (T3) levels were affected by the contaminants investigated. Selenium variables in muscle were positively correlated with both TT3 and the total to free T3 (TT3:FT3) ratio, where the Se:Hg molar ratio was the best predictor of TT3, and Se was the best predictor of TT3:FT3. The Se:Hg ratio in muscle tissue also was an important predictor of total T4, and a weaker predictor of FT4 levels in the trout. Furthermore, Hg alone also correlated negatively with several T4 variables. It is suggested that Se acts as an antagonist against Hg induced TH disruptive effects, and that trout from Lake Mjøsa may be susceptible to effects due to low Se levels in the lake. Hepatic concentration of several heavy metals, especially cadmium and chromium, were also negatively related to T3 levels. Plasma THs were not well correlated with the POPs, but weak negative effects on TT4 and total to free T4 (TT4:FT4) were observed for several PBDEs and polychlorinated biphenyls (PCBs). Biomarkers of increased hepatic oxidative stress (the glutathione system) were not linked to depleted TH levels, but associated with bioavailability of Se, which likely accounted for the positive correlation between oxidized glutathione and T3 in the trout. Since relationships between THs and trace elements were stronger than relationships between THs and POPs, it is suggested that measurements of both POPs and trace elements should be included in studies that aim to investigate TH disruptive effects in free-ranging freshwater fish.

.

High levels of persistent organic pollutants (POPs) have been detected in the Arctic wildlife. While many of the traditional POPs have been reported to decline the last decades, emerging contaminants such as perfluoroalkyl substanses (PFASs) have been detected in increasing amounts in biota worldwide. PFOS has been the major PFASs detected and the leading manufacturer of PFOS announced a voluntarily phase-out of the perfluorooctanesulfonyl fluoride (POSF) chemistry and ended the production in 2002. However, other PFASs are still being used in the industry and no regulations have been established. The toxicological effects of PFASs are not fully elucidated, but they have been linked to hepatotoxicity, developmental toxicity, immunotoxicity and disruption of hormone homeostasis.The aim of this study was to investigate temporal changes of PFASs and to evaluate possible relationships between PFASs and circulating thyroid hormone (TH) levels in polar bear (Ursus maritimus) mother-cub pairs from Svalbard sampled in 1998 (12 mother-cub pairs) and 2008 (9 mother-cub pairs). Plasma samples from all polar bears were extracted by liquid-liquid extraction (LLE) using methanol and analysed for perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorotridecanoic acid (PFTrDA), perfluorotetradecanoic acid (PFTrDA), perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS) and perfluorooctane sulfonamide (PFOSA) using liquid chromatography – mass spectrometry (LC-MS). Total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3) and free triiodothyronine (FT3) were quantified by the use of radioimmunoassay (RIA). Relationships between PFASs, THs, age (only mothers), capture day and biometric variables were investigated by the use of principle component analysis (PCA) and general linear models (GLM).PFHpA, PFOA and PFOS showed significant decreasing levels in mothers, while the levels did not differ between the years in cubs. In contrast, the longest chain perfluorinated carboxylic acids (PFCAs) showed significantly increasing concentrations over time in both mothers (PFNA, PFUnDA, PFDoDA, PFTrDA) and cubs (PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA, PFTeDA). Concentration of PFBA, PFPeA and PFHxA were not detected in mothers or cubs, PFBS was detected in one mother and PFOSA was only detected sporadically. A positive relationship was observed between the longest chain PFCAs and TT3 in both mothers and their offspring, particularly with regard to PFTrDA in mothers and PFDoDA in cubs. In addition, TT3 and body mass were positively correlated in cubs. In contrast to the longest chain PFCAs, no relationships were observed between PFOS and THs in the polar bear plasma samples. The positive correlation between TT3 and the longest chain PFCAs may indicate a possible interaction between PFCAs and the TH homeostasis in polar bear mother-cub pairs. However, no final conclusions can be drawn based on the mechanism behind this finding and further research is needed on these emerging contaminants to elucidate their potential TH-disrupting effects.

Polluted soil can be a problem in urban areas, and can have a direct impact on human health upon exposure. The toxic potential of mixtures can be mediated by constituents and information about toxicity of mixtures is regarded as important, as it represents the real exposure situation. The main purpose of this project was to measure the mutagenic and CYP1A inducing potential in vitro from organic extracts of soil, sampled in nursery schools in Oslo. Selection of soil was mainly based on the content of ∑PAH16 and ∑PCB7, chemical groups known to include CYP1A inducing and/or genotoxic and mutagenic compounds. Generally were Soil 1 considered as a “clean” sample, Soil 2 to Soil 4 contained increasing level of PAHs and Soil 5 contained mainly elevated levels of PCBs. Assessing varying samples in relation to chemical content was valuable due to potential differences in biological responses. The soil samples were of top soil (0- 2 cm depth) and had been collected by NGU in connection to a geological survey of soil at playgrounds in nursery schools and schools in Norway. The soil was sampled in 2005- 2007, dried at 40 °C for one to two weeks, sieved in a 2 mm nylon sieve and stored in the dark at room temperature. Chemical analyses of both inorganic and organic compounds were performed before storage. In relation to this master project the organic pollutants in the selected soil samples were extracted by ultrasonic agitation in dichloromethane (DCM). Before experimental use the solvent was changed into dichloromethane (DMSO) by evaporating off the DCM using a water bath at 25 °C and a flow of nitrogen above. The dried extracts were redissolved in DMSO.The Ames Salmonella typhimurium assay was used for measuring mutagenicity. The presence of primary and secondary mutagens was assessed by conducting the assay both with and without addition of a metabolic S9- mix. Induction of different point mutations was revealed by utilising two bacterial strains, TA98 and TA100, detecting frameshift and base- pair substitutions, respectively. Induction of CYP1A enzymes was assessed in the rat H4IIE hepatoma cell line, and measured immunologically by Western blotting. The exposure concentrations used in the CYP1A assay were based on results of cell viability, assessed by utilising MTT- assay for finding the highest non- cytotoxic exposure concentrations. Concentration ranges of the extracts were tested in both assays. The mutagenic potential of extracts showed presence of secondary mutagenic compounds, and indicated absence or very low levels of primary mutagens. It was a general incidence of higher mutagenic activity with TA98 than TA100, reflecting highest induction of frameshift mutations. The inducing potential of extracts was in accordance with chemical analysis, showing a general increase in the potential of extract from Soil 1 to Soil 4, suggested to partly reflect differences in level of PAHs. The relative low potency of extract from Soil 5 was considered to be a reflection of a low content of PAHs and an expected dominance of PCBs, which have shown not to induce mutagens in the Ames assay.Induction of CYP1A in H4IIE was measured after exposure to extracts of Soil 3, Soil 4 and Soil 5. Results clearly indicated presence of CYP1A inducers in the extracts. A positive concentration- effect relationship was detected from exposure to extract of Soil 5. Extract of Soil 3 and Soil 4 did clearly induce CYP1A, but in a negative concentration dependent manner. These negative responses were suggested to indicate inhibition of CYP1A induction at the higher concentration, which may be linked to antagonism at the Ah- receptor. The biological endpoints measured in the current project reflected the integrated effect from extract exposure, potentially affected by additivity, synergism and/or antagonism. Differences in toxicity between in vitro and in vivo conditions, along with several biological and environmental parameters can affect the biological responses. The results obtained in the current project indicated presence of potential hazards in the soil, but no further conclusion could be drawn about the actual hazard from humans exposure to polluted soil.

The glaucous gull (Larus hyperboreus) is one of the largest flying top predators in the Arctic and is exposed to rather high levels of different persistent organohalogenated contaminants (OHCs). The present study investigated whether the serum thyroid hormone (TH) levels in female glaucous gulls breeding in Kongsfjorden (79oN) may be affected by the various OHCs. A slight decrease in traditional OHCs, like polychlorinated biphenyls (PCBs) and some pesticides have been reported over the last decade, while increasing levels of new and emerging compounds like polybrominated diphenyl ethers (PBDEs) and perfluoroalkyl substances (PFASs) are detected in Arctic marine and terrestrial wildlife. Although further production of some possible endocrine disruptive chemicals have been banned by many nations, the chemicals persist, move throughout the biosphere and are potentially harmful to exposed wildlife and biota.After 35 years of contaminant research, the Svalbard glaucous gull function as a bioindicator species. Previous assessments have concluded that OHC levels were high enough to be of concern for a number of physiological effects, among them endocrine alterations. However, this is to my knowledge the first biomarker study on levels of THs in breeding glaucous gulls from Kongsfjorden. Plasma from 19 nesting female glaucous gulls was analysed for PCBs, organochlorinated pesticides (OCPs) (such as dichlorodiphenyltrichloroethane [DDT] and chlordanes) and their metabolites, PBDEs and PFASs. Total and free ranging THs were quantified using radioimmuno assay (RIA). Multivariate statistics were used to investigate the relationships between the TH levels and the explanatory variables.The PCBs represented the most pervasive compound group in the present study, as 61.3 % of the total contaminant burden in female glaucous gulls. The other contaminant groups contributed as follows: ΣDDTs (17.5 %) > ΣPFASs (14.8 %) > HCB (2.9 %) > ΣCHLs (2.7 %) > ΣPBDE (0.8 %) > ΣHCH (0.1 %). Several of the PFASs correlated significantly with the THs. Significant correlations were found between several of the long-chain Perfluoroalkyl carboxylates (PFCAs) and THs. Surprisingly, even though the PFCAs represented only 2.8 % of the total contaminant load in the present study, the PFCAs represented the most important variables explaining the variation in THs.

Thesis (Ph.D.)--Drexel University, 2008. / Includes abstract and vita. Includes bibliographical references (leaves 138-147).

Vision is a crucial aspect of life for humans and animals. Impaired vision can lead to reduced quality of life along with other complications. Cataracts are a leading cause of impaired vision and blindness worldwide. Cataracts develop as a process of aging, although several environmental and lifestyle factors increase the risk of this disease. The toxic metal cadmium (Cd) has been associated with cataract formation and other ocular diseases such as macular degeneration. Cadmium exposure experiments were conducted to investigate potential pathways or mechanisms by which Cd may contribute to cataract formation and ocular disease. Zebra fish larvae (72, 96, and 120 hours post fertilization), adult zebra sh (6-month male, 10-month male, and 10-month female) and the B3 human lens epithelial (HLE) cell line were acutely exposed to varying concentrations of Cd. Transcriptomic changes relative to control (0 μM Cd) were determined using microarray analysis for zebra sh larvae and RNA sequencing (RNA-Seq) for adult zebra sh and HLE cells. Gene Ontology (GO) enrichment analysis for the zebra sh larvae exposure (50 μM Cd for 4 or 8 hours) enriched the "retina development in camera-type eye" term, and genes involved in enrichment (dnmt1, ccna2, fen1, mcm3 and slbp) were down-regulated. Gene set enrichment analysis (GSEA) for the 10-month male zebra sh exposure (50 μM Cd for 4 hours) enriched the "embryonic eye morphogenesis" gene set and signi ficant genes involved in enrichment (tcf7l1a, pitx2, fzd8a, sfrp5, lmx1bb, mfap2, six3b, lum, phactr4b, and foxc1a) were down-regulated. GSEA for the 10-month female zebra sh (50 μM Cd for 4 hours) enriched the "photoreceptor cell differentiation" gene set and signi cant genes involved in enrichment (odc1, thrb, and ush2a) were up-regulated. GO enrichment analysis for up-regulated genes in the HLE cell exposure (10 μM Cd for 4 hours) enriched the terms "eye development" (22 genes) and "lens development in camera-type eye" (CITED2, SKIL, CRYAB, SLC7A11, TGFB2, EPHA2, BCAR3, WNT5B, and BMP4). These results show cadmium is capable of altering transcription of eye-related genes in both zebra sh and human models, which may contribute to the formation of ocular disease. Many of these genes are involved in lens and retina development, yet they are also associated with diseases in these eye structures. Future studies could assess the consequences of altered transcription of these genes which could help elucidate the mechanisms of these changes and the overall effect of cadmium exposure on ocular disease. Ultimately, our study characterized the regulation of eye-related genes in response to Cd exposure and provided valuable knowledge laying the foundation for identi fication of the molecular mechanisms contributing to ocular diseases. / Thesis / Master of Science (MSc) / The eye is a sphere-like organ which is important for visualizing your surroundings. It is composed of many different structures such as the cornea, lens and retina. Many eye diseases have been characterized by abnormalities in eye structures; for example, a cataract occurs when the lens becomes cloudy and unable to focus light while macular degeneration is defined by progressive deterioration of the retinal macula region. While these diseases can occur through the natural aging process, certain environmental factors can increase risk. Exposure to cadmium, a toxic heavy metal which causes negative effects in animals, has shown to be associated with eye disease like cataracts and macular degeneration. In order to expand on this knowledge, we exposed both zebrafish and human lens cells to cadmium. By utilizing different experimental methods such as microarray analysis and RNA sequencing, eye-related genes which were affected by cadmium were revealed. Identifying the relationship between eye diseases, cadmium and gene expression will help identify the mechanism by which cadmium contributes to eye disease formation.

Anthropogenically driven climate change not only results in rising of sea temperature but also leads to more frequent and longer-lasting cold and heat waves. Meanwhile, coastal marine ecosystems are constantly challenged by increasing threats of chemical pollution. Temperature and chemical stressors can jointly affect the livelihood of marine organisms, but their combined effects are still poorly understood. Therefore, this study aimed to investigate the effects of thermal stress and chemical exposure on the marine medaka Oryzias melastigma, copepod Tigriopus japonicus and rotifer Brachionus koreanus. The four selected chemical contaminants included copper sulphate pentahydrate (Cu), dichlorophenyltrichloroethane (DDT), triphenyltin chloride and copper pyrithione. It was hypothesized that marine organisms are more susceptible to chemical exposure at both cold and warm extremes. In vivo acute ecotoxicity tests were conducted over a wide temperature range to ascertain the relationship between thermal stress and chemical toxicity. For O. melastigma larvae, the lowest toxicity occurred at an optimum temperature range; the chemical toxicity further increased with temperature increase or decrease from this optimum, and exacerbated at extremely low and high temperatures. For T. japonicus and B. koreanus, the chemical toxicity generally increased with increasing temperature. Such inter-species dissimilarities were possibly due to differences in the uptake route, detoxification mechanism, avoidance behaviour and physiological response between the fish and the copepod or rotifer. Experiments were conducted to evaluate the temperature-dependent physiological and biochemical responses, and thermal tolerance of O. melastigma larvae. The growth in the fish larvae showed an inverse and negatively skewed V-shape relationship with temperature, with a significant reduction in performance at both low and high thermal extremes. A mismatch between demand and supply of oxygen and energy under extremely cold and warm conditions was probably the primary cause of growth inhibition and metabolic impairment, leading to a temporary adaptation by a shift to anaerobiosis and an induction of heat shock proteins (HSPs). Temperatures at both cold and warm extremes increased toxicities of DDT and Cu to O. melastigma larvae, resulting in restricted growth and interrupted oxygen consumption rate. The fish larvae modulated their metabolic pathway and produced stress proteins (i.e., HSPs and metallothioneins) for adaptation to the combined stress. However, such responses were disrupted by combinations of thermal extremes, in particular high temperature, and high chemical concentration. Most importantly, both DDT and Cu exposure significantly reduced the thermal tolerance of the fish larvae. The interacting effect of temperature and Cu was also investigated on T. japonicus. The results showed that their combined effect could significantly reduce the survival, lengthen the developmental time and change the sex ratio of the copepod. Transcriptions of several stress-related genes (i.e., glutathione reductase, glutathione S-transferases and HSPs) in the adult T. japonicus were significantly affected by the joint-effect of temperature and Cu exposure, implying that these genes played essential roles in protecting the cellular integrity against the stresses. This study advanced the understanding on the temperature-dependent toxicity of chemical contaminants to marine organisms, and provided valuable information and empirical models for deriving water quality criteria of chemical contaminants at various temperatures. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Hydrocarbon contamination of soils has increased worldwide and bioremediation offers an attractive and environmentally friendly solution to this problem. However, the efficiency and completion of remediation must be assessed using environmental risk assessment criteria. As a result, a variety of indicators have become essential for determining and evaluating recovery of contaminated soils. In this study, microbiological and toxicological assays are used to support traditional chemical analyses, to identify a suite of assays suitable for determining a Soil Recovery Index from Pollution (SRIP). Microbiological assays used are microbial biomass carbon (Cmic), plate counts for culturable degraders and general heterotrophs enzyme activities (dehydrogenase and phosphatase), basal respiration, Substrate Induced Respiration (SIR), and bacterial biosensor. Toxicological response assays of higher organisms include two species of earthworms (Eisenia fetida and Lumbricus terrestris), also, plant assays, including seed germination, root elongation, germination index and plant shoot height performed using two species of plant wheat (Triticum aestivum L.) and white mustard (Brassica alba L.). All assays were applied sequentially to kerosene and diesel amended soils for both incubated and non–incubated treatments. The indicators were discriminated in terms of their sensitivity using a ranking system. The data collected were integrated into a single numeric value to reflect a ‘level of concern’ for each soil treatment. Soil characteristics and hydrocarbon types play key roles in the response of these indicators. The soil that had high organic matter and clay content was less affected by hydrocarbons. For the freshly hydrocarbon amended soils, kerosene was more toxic than diesel, however the opposite was found in the incubated hydrocarbon amended treatments. The most sensitive and robust indicators were basal respiration, bacterial heterotrophs and degraders counts, bacterial biosensors (methanol extracted soils), earthworm survival, mustard root elongation and mustard plant shoot height. Sensitive indicators were inserted into the SRIP. The SRIP indicates the “level of concern” for each soil treatment in a single value.