| dc.description.abstract | Atlantic cod caged in three different locations at the coastline of Stavanger, were monitored to look at the potential oxidative stress effect caused by pharmaceutical contaminations in selected areas. The first station (Station 1) was located west of Kvitsøy and was used as the reference station. The second station (Station 2) was located east of Kvitsøy, nearby a salmon aquaculture facility. The third station (Station 3) was located at the wastewater treatment plant (WWTP) discharge of IVAR.
The biomarkers used to measure oxidative stress, using gene expression analyses, were: catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD), aryl hydrocarbon receptor 2 (AhR2), cytochrome P450 (CYP1a), glutathione peroxidase (GPx) and heat shock protein 70 (HSP70). In addition, specific biochemical assays were used. These were glutathione peroxidase (GPx) activity assay and lipid peroxidation (MDA) activity assay.
Data was evaluated for differences in gene expression from both males and females together and separately in different stations. Summarising the results, the gene expression of HSP70 remained the same in liver of fish caged at the station 3 compared to liver samples from fish caged at station 1. The gene expression of GR, CYP1a, and AhR2 increased in liver from fish caged at station 3 compared to liver samples from fish caged at station 1, with a significant difference in expression for CYP1a and AhR2. The expression of GST decreased in liver of fish caged at station 3 compared to fish liver caged at station 1.
The gene expression of CAT, SOD, and GPx in liver from fish caged at station 3 varied between females and males, and when the females and males were combined, when the expression was compared to station 1. The gene expression of SOD in liver from fish caged at station 2 increased significantly when combined with expression in liver from fish caged at station 1. The expression of SOD in liver from male fish caged at station 3 increased, while the expression decreased significantly in liver from female fish caged at station 3, when compared with liver from fish caged at station 1. The same trend in expression was seen with GPx. The expression of CAT in liver from fish caged at station 3 remained the same when combined with liver from fish caged at station 1. The gene expression of CAT in liver from male fish caged at station 3 decreased, while the gene expression of CAT in liver from female fish caged at station 3 increased when compared with expression in liver from fish caged at station 1. The activity of GPx and MDA was measured, and the activity for both decreased significantly at station 3 compared with station 1.
Results showed that fish caged at station 3, in the proximity of the WWTP discharge were affected by the contaminants from the WWTP discharge, but decreased lipid peroxidation could indicate that no oxidative stress was developed.
In future studies, it would be interesting to evaluate the effect on gene expression in liver of fish exposed to pharmaceuticals analysed in the WWTP discharge of IVAR under laboratory conditions to examine the mixture effect of the pharmaceuticals. Also, it would also be interesting to evaluate the effect on gene expression in other tissues of fish exposed to pharmaceuticals analysed in the WWTP discharge of IVAR, both under environmental and laboratory conditions. The results should be analysed both station specific and sex specific, to examine possible differences between males and females. In addition, other species could be examined for the same biomarkers to be able to provide a full environmental risk assessment for the WWTP discharges. | |