Effects of redox cycling compounds on DT diaphorase activity in the liver of rainbow trout (Oncorhynchus mykiss)

BACKGROUND: DT diaphorase (DTD; NAD(P)H:quinone oxidoreductase; EC 1.6.99.2) catalyses the two electron reduction of quinones, thus preventing redox cycling and consequently quinone dependent production of reactive oxygen species. In rat and mouse, a wide range of chemicals including polyaromatic hydrocarbons, azo dyes and quinones induces DTD. Bifunctional compounds, such as β-naphthoflavone (β-NF) and benzo(a)pyrene (B(a)P), induce DTD together with CYP1A and phase II enzymes by a mechanism involving the aryl hydrocarbon receptor (AHR). Monofunctional induction of DTD is mediated through the antioxidant response element and does not lead to the induction of AHR dependent enzymes, such as CYP1A. The aim of this study was to investigate the effects of prooxidants (both bifunctional and monofunctional) on the activity of hepatic DTD in rainbow trout (Oncorhynchus mykiss) in order to evaluate DTD suitability as a biomarker. We also investigated the effect of β-NF on hepatic DTD activity in perch (Perca fluviatilis), shorthorn sculpin (Myoxocephalus scorpius), eelpout (Zoarces viviparus), brown trout (Salmo trutta) and carp (Cyprinus carpio). In addition, the effect of short term exposure to prooxidants on catalase activity was investigated. RESULTS: In rainbow trout, hepatic DTD activity is induced by the bifunctional AHR agonists β-NF and B(a)P and the monofunctional inducers naphthazarin, menadione and paraquat. Although exposure to both B(a)P and β-NF led to a strong 7-ethoxyresorufin-O-deethylase (EROD) induction, none of the monofunctional compounds affected the rainbow trout EROD activity. DTD was not induced by β-NF in any of the other fish species. Much higher DTD activities were observed in rainbow trout compared to the other fish species. Catalase activity was less responsive to short term exposure to prooxidants compared to DTD. CONCLUSION: Since rainbow trout hepatic DTD activity is inducible by both monofunctional and bifunctional inducers, it is suggested that rainbow trout DTD may be regulated by the same mechanisms, as in mammals. The fact that DTD is inducible in rainbow trout suggests that the enzyme may be suitable as a part of a biomarker battery when rainbow trout is used in environmental studies. It appears as if DTD activity in rainbow trout is higher and inducible compared to the other fish species studied

Analysis of the importance of lipid breakdown for elimination of okadaic acid (diarrhetic shellfish toxin) in mussels, Mytilus edulis: results from a field study and a laboratory experiment. Aquatic Toxicol

Abstract Okadaic acid (OA) is a lipophilic phycotoxin, which accumulates in the digestive organs of mussels and may cause diarrhetic shellfish poisoning (DSP) in humans. Depuration of toxic mussels is a potential option for the shellfish industry to increase the availability of marketable mussels. To develop cost-effective depuration methods for DSP toxins, knowledge about the environmental conditions and physiological processes regulating the rate of depuration is essential. In this paper, the importance of lipid breakdown for elimination of OA in mussels was investigated by performing a field study and a manipulative laboratory experiment. First, total lipid content and concurrent concentration of OA in the digestive glands of farmed blue mussels, Mytilus edulis, was analysed on a monthly basis from January to June 2000. A significant positive correlation between levels of OA and lipid content was observed between January and March, when lipid levels were showing a decreasing trend. This supported a previously proposed model that breakdown of lipid stores may affect the release and elimination of this lipophilic toxin. To test this causal model, a laboratory experiment was performed. Mussels containing OA were exposed to experimental treatments (increased seawater temperature and/or food limitation) for 24 days in order to increase the energy requirements and need to use lipids as an energy source. It was predicted that mussels exposed to these treatments would have a faster elimination rate of OA compared to feeding mussels kept in ambient seawater temperature. The results showed that lipid content was significantly reduced in mussels exposed to an increased water temperature (24 • C) compared to ambient temperature (18 • C). The amount of lipids was not affected by food limitation. Although lipid content was reduced in 24 • C, the rate of depuration of OA was not faster for mussels in this treatment and no correlation was detected between lipid content and OA. Depuration rates were very similar for all treatments and followed an exponential decrease relationship (t 1/2 = 8 days). Thus, the proposed model that lipid breakdown affects the mechanism of elimination of OA was not supported. Nevertheless, the observed rates of depuration provide useful information and a potential predictive tool for large-scale depuration methods of mussels. The difficulties to influence the rate of depuration of this toxin by changing the environmental conditions suggest that processes, insensitive to short-term manipulation of the external environment, regulate depuration of OA

Characterization of the Zoarces viviparus liver transcriptome using massively parallel pyrosequencing

<p>Abstract</p> <p>Background</p> <p>The teleost <it>Zoarces viviparus </it>(eelpout) lives along the coasts of Northern Europe and has long been an established model organism for marine ecology and environmental monitoring. The scarce information about this species genome has however restrained the use of efficient molecular-level assays, such as gene expression microarrays.</p> <p>Results</p> <p>In the present study we present the first comprehensive characterization of the <it>Zoarces viviparus </it>liver transcriptome. From 400,000 reads generated by massively parallel pyrosequencing, more than 50,000 pieces of putative transcripts were assembled, annotated and functionally classified. The data was estimated to cover roughly 40% of the total transcriptome and homologues for about half of the genes of <it>Gasterosteus aculeatus </it>(stickleback) were identified. The sequence data was consequently used to design an oligonucleotide microarray for large-scale gene expression analysis.</p> <p>Conclusion</p> <p>Our results show that one run using a Genome Sequencer FLX from 454 Life Science/Roche generates enough genomic information for adequate <it>de novo </it>assembly of a large number of genes in a higher vertebrate. The generated sequence data, including the validated microarray probes, are publicly available to promote genome-wide research in <it>Zoarces viviparus</it>.</p

Sensitive and robust gene expression changes in fish exposed to estrogen – a microarray approach

<p>Abstract</p> <p>Background</p> <p>Vitellogenin is a well established biomarker for estrogenic exposure in fish. However, effects on gonadal differentiation at concentrations of estrogen not sufficient to give rise to a measurable vitellogenin response suggest that more sensitive biomarkers would be useful. Induction of zona pellucida genes may be more sensitive but their specificities are not as clear. The objective of this study was to find additional sensitive and robust candidate biomarkers of estrogenic exposure.</p> <p>Results</p> <p>Hepatic mRNA expression profiles were characterized in juvenile rainbow trout exposed to a measured concentration of 0.87 and 10 ng ethinylestradiol/L using a salmonid cDNA microarray. The higher concentration was used to guide the subsequent identification of generally more subtle responses at the low concentration not sufficient to induce vitellogenin. A meta-analysis was performed with data from the present study and three similar microarray studies using different fish species and platforms. Within the generated list of presumably robust responses, several well-known estrogen-regulated genes were identified. Two genes, confirmed by quantitative RT-PCR (qPCR), fulfilled both the criteria of high sensitivity and robustness; the induction of the genes encoding zona pellucida protein 3 and a nucleoside diphosphate kinase (nm23).</p> <p>Conclusion</p> <p>The cross-species, cross-platform meta-analysis correctly identified several robust responses. This adds confidence to our approach used for identifying candidate biomarkers. Specifically, we propose that analyses of an nm23 gene together with zona pellucida genes may increase the possibilities to detect an exposure to low levels of estrogenic compounds in fish.</p

Faktablad från integrerad kustfiskövervakning i Egentliga Östersjön, 2014

I svensk kustfiskövervakning ingår ett antal referensområden som anses obetydligt påverkade av lokal mänsklig aktivitet. Syftet med övervakningen är att kartlägga tillståndet för fisksamhället i dessa referensområden, spegla naturliga variationer på bestånds- och individnivå, samt upptäcka förändringar som indikerar storskalig påverkan av miljöhot som eutrofiering, miljögifter, klimatförändringar och andra miljöfaktorer. De årliga fiskundersökningarna i Kvädöfjärden i södra Östergötland ingår i programmet för integrerad kustfiskövervakning inom den nationella havsmiljöövervakningen. Kvädöfjärden utvaldes i slutet av 1980-talet som ett lämpligt nationellt referensområde för Egentliga Östersjön. Undersökningsområdet ligger till stora delar inom Torrö och Åsvikelandets naturreservat

Faktablad från integrerad kustfiskövervakning i södra Egentliga Östersjön, 2014

I svensk kustfiskövervakning ingår ett antal referensområden som anses obetydligt påverkade av lokal mänsklig aktivitet. Syftet med övervakningen är att kartlägga tillståndet för fisksamhället i dessa referensområden, spegla naturliga variationer på bestånds- och individnivå, samt upptäcka förändringar som indikerar storskalig påverkan av miljöhot som eutrofiering, miljögifter och klimatförändringar och andra miljöfaktorer. De årliga fiskundersökningarna vid Torhamn i Blekinge skärgård ingår i programmet för integrerad kustfiskövervakning inom den nationella havsmiljöövervakningen. Torhamnsområdet utvaldes i början av 2000-talet som ett lämpligt nationellt referensområde för södra Östersjön. Torhamns skärgård är klassad som ett område av riksintresse för naturvård och har genomgått en naturreservatsinventering

Kvädöfjärden, Egentliga Östersjön, 1981–2021

Inom den nationella miljöövervakningen av kust och hav bedrivs årligen sedan slutet av 1980-talet ett program för integrerad kustfiskövervakning. Programmet startades i slutet av 1980-talet och omfattar i dagsläget sju nationella referensområden; två i Bottniska viken, ett i norra Egentliga Östersjön, två i södra Egentliga Östersjön och två i Västerhavet.Syftet med programmet är att kartlägga fiskbeståndens status samt fiskens hälsotillstånd och miljögiftsbelastning för att upptäcka förändringar som indikerar storskalig påverkan av miljöhot som eutrofiering, miljögifter, klimatförändringar och andra miljöfaktorer.Detta faktablad sammanfattar resultat och bedömningar från den integrerade kustfiskövervakningen i referensområdet Kvädöfjärden i södra Östergötland. För en fördjupad presentation av resultaten se; Faktablad för Integrerad kustfisk-övervakning (Fjällbacka, Torhamn, Kvädöfjärden och Holmöarna), 2020: