Phenanthrene alters the electrical activity of atrial and ventricular myocytes of a polar fish, the Navaga cod.

Oil and gas exploration in the Arctic can result in the release of polycyclic aromatic hydrocarbons (PAHs) into relatively pristine environments. Following the recent spill of approximately 17 500 tonnes of diesel fuel in Norilsk, Russia, May 2020, our study focussed on the effects of phenanthrene, a low molecular weight PAH found in diesel and crude oil, on the isolated atrial and ventricular myocytes from the heart of the polar teleost, the Navaga cod (Eleginus nawaga). Acute exposure to phenanthrene in navaga cardiomyocytes caused significant action potential (AP) prolongation, confirming the proarrhythmic effects of this pollutant. We show AP prolongation was due to potent inhibition of the main repolarising current, IKr, with an IC50 value of ~2 µM. We also show a potent inhibitory effect (~55%) of 1 µM phenanthrene on the transient IKr currents that protects the heart from early-after-depolarizations and arrhythmias. These data, along with more minor effects on inward sodium (INa) (~17% inhibition at 10 µM) and calcium (ICa) (~17% inhibition at 30 µM) currents, and no effects on inward rectifier (IK1 and IKAch) currents, demonstrate the cardiotoxic effects exerted by phenanthrene on the atrium and ventricle of navaga cod. Moreover, we report the first data that we are aware of on the impact of phenanthrene on atrial myocyte function in any fish species.

Accumulation and toxicity of monoaromatic petroleum hydrocarbons in early life stages of cod and haddock.

A multitude of recent studies have documented the detrimental effects of crude oil exposure on early life stages of fish, including larvae and embryos. While polycyclic aromatic hydrocarbons (PAHs), particularly alkyl PAHs, are often considered the main cause of observed toxic effects, other crude oil derived organic compounds are usually overlooked. In the current study, comprehensive two-dimensional gas chromatography coupled to mass spectrometry was applied to investigate the body burden of a wide range of petrogenic compounds in Atlantic haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) embryos that had been exposed to sublethal doses of dispersed crude oil. Several groups of alkylated monoaromatic compounds (e.g. alkyl tetralins, indanes and alkyl benzenes), as well as highly alkylated PAHs, were found to accumulate in the fish embryos upon crude oil exposure. To investigate the toxicity of the monoaromatic compounds, two models (1-isopropyl-4-methyltetralin and 1-isopropyl-4-methylindane) were synthesized and shown to bioaccumulate and cause delayed hatching in developing embryos. Minor developmental effects, including craniofacial and jaw deformations and pericardial edemas, were also observed at the highest studied concentrations of the alkylindane.

Effects of acute exposure to dispersed oil and burned oil residue on long-term survival, growth, and reproductive development in polar cod (Boreogadus saida).

The present study investigates the potential long-term physiological effects on maturing polar cod (Boreogadus saida), an Arctic key species, after an acute exposure (48 h) to environmentally realistic concentrations of either mechanically dispersed oil (MDO), chemically dispersed oil (CDO) or burned oil residues (BO) (N = 58-60 per treatment). Following exposure, fish were monitored in a common tank supplied with clean water for a seven-month period coinciding with the period of reproductive development. Females exposed to BO residues were more frequently found in an earlier phase of gonadal maturation compared to unexposed females while no effects of different oil spill response (OSR) actions were seen in the reproductive development of males. Mechanically and chemically dispersed oil induced a transient short-term reduction in growth in the first week post-exposure. Overall, no significant long-term effects of exposure were seen in growth or mortality. Ultimately, this study provides information for the assessment of population consequences of different OSR actions as part of a net environmental benefit analysis.

Adhesion of mechanically and chemically dispersed crude oil droplets to eggs of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus).

Crude oil accidentally spilled into the marine environment undergoes natural weathering processes that result in oil components being dissolved into the water column or present in particulate form as dispersed oil droplets. Oil components dissolved in seawater are typically considered as more bioavailable to pelagic marine organisms and the main driver of crude oil toxicity, however, recent studies indicate that oil droplets may also contribute. The adhesion of crude oil droplets onto the eggs of pelagic fish species may cause enhanced transfer of oil components via the egg surface causing toxicity during the sensitive embryonic developmental stage. In the current study, we utilized an oil droplet dispersion generator to generate defined oil droplets sizes/concentrations and exposed Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) to investigate if the potential for dispersed oil droplets to adhere onto the surface of eggs was species-dependent. The influence of a commercial chemical dispersant on the adhesion process was also studied. A key finding was that the adhesion of oil droplets was significantly higher for haddock than cod, highlighting key differences and exposure risks between the two species. Scanning electron microscopy indicates that the differences in oil droplet adhesion may be driven by the surface morphology of the eggs. Another important finding was that the adhesion capacity of oil droplets to fish eggs is significantly reduced (cod 37.3%, haddock 41.7%) in the presence of the chemical dispersant.

Effects of dietary crude oil exposure on molecular and physiological parameters related to lipid homeostasis in polar cod (Boreogadus saida).

Polar cod is an abundant Arctic key species, inhabiting an ecosystem that is subjected to rapid climate change and increased petroleum related activities. Few studies have investigated biological effects of crude oil on lipid metabolism in this species, despite lipids being a crucial compound for Arctic species to adapt to the high seasonality in food abundance in their habitat. This study examines the effects of dietary crude oil exposure on transcription levels of genes related to lipid metabolism (peroxisome proliferator-activated receptors [ppar-α, ppar-γ], retinoic X receptor [rxr-ß], palmitoyl-CoA oxidase [aox1], cytochrome P4507A1 [cyp7α1]), reproduction (vitellogenin [vtg-ß], gonad aromatase [cyp19a1]) and biotransformation (cytochrome P4501A1 [cyp1a1], aryl hydrocarbon receptor [ahr2]). Exposure effects were also examined through plasma chemistry parameters. Additional fish were exposed to a PPAR-α agonist (WY-14,643) to investigate the role of PPAR-α in their lipid metabolism. The dose-dependent up-regulation of cyp1a1 reflected the activation of genes related to PAH biotransformation upon crude oil exposure. The crude oil exposure did not significantly alter the mRNA expression of genes involved in lipid homeostasis except for cyp7α1 transcription levels. Plasma levels of cholesterol and alanine transaminase showed significant alterations in fish exposed to crude oil at the end of the experiment. WY exposure induced a down-regulation of ppar-α, an effect contrary to studies performed on other fish species. In conclusion, this study showed clear effects of dietary crude oil exposure at environmentally relevant concentrations on xenobiotic biotransformation but revealed only weak alterations in the lipid metabolism of polar cod.

Effects of crude oil exposure and elevated temperature on the liver transcriptome of polar cod (Boreogadus saida).

Petroleum-related activities in the Arctic have raised concerns about the adverse effects of potential oil spill on the environment and living organisms. Polar cod plays a key role in the Arctic marine ecosystem and is an important species for monitoring oil pollution in this region. We examined potential interactions of oil pollution and global warming by analysing liver transcriptome changes in polar cod exposed to crude oil at elevated temperature. Adult males and females were kept at high (11°C) or normal (4°C) temperature for 5 days before exposure to mechanically dispersed crude oil for 2 days followed by recovery in clean sea water for 11 days at the two temperatures. Genome-wide microarray analysis of liver samples revealed numerous differentially expressed genes induced by uptake of oil as confirmed by increased levels of bile polycyclic aromatic hydrocarbon (PAH) metabolites. The hepatic response included genes playing important roles in xenobiotic detoxification and closely related biochemical processes, but also of importance for protein stress response, cell repair and immunity. Though magnitude of transcriptome responses was similar at both temperatures, the upregulated expression of cyp1a1 and several chaperone genes was much stronger at 11°C. Most gene expression changes returned to basal levels after recovery. The microarray results were validated by qPCR measurement of eleven selected genes representing both known and novel biomarkers to assess exposure to anthropogenic threats on polar cod. Strong upregulation of the gene encoding fibroblast growth factor 7 is proposed to protect the liver of polar fish with aglomerular kidneys from the toxic effect of accumulated biliary compounds. The highly altered liver transcriptome patterns after acute oil exposure and recovery suggests rapid responses in polar cod to oil pollutants and the ability to cope with toxicity in relatively short time.

[Lipid profile analysis of two species of hake "merluccius capensis and merluccius paradoxus" and its contribution to cardiovascular disease prevention]. / Análisis del perfil lipídico de dos especies de merluza "Merluccius capensis y Merluccius paradoxus" y su aportación a la prevención de enfermedades cardiovasculares.

INTRODUCTION: In recent years it has been shown that omega-3 PUFAs have multiple cardiovascular protective effects. Currently, fish is the main and most important source of Omega-3 fatty acids. OBJECTIVE: To analyze the fatty acid composition in two species of hake, its content of omega-3 fatty acids and study their contribution to the prevention of cardiovascular diseases. MATERIAL AND METHODS: We analyzed samples of two species of hake (Merluccius capensis and Merluccius paradoxus) in its natural state and frozen, cooked by microwave and boiled samples. We have studied the moisture content, lipid content and analysis, identification and composition of fatty acids. RESULTS: It was observed that the content of w-3 PUFA was higher than the w-6 PUFA. The omega-3 fatty acids DHA and EPA were the most representative of the omega-3 family, highlighting the DHA content in all samples analyzed. It has also demonstrated the safety of the cooking methods :microwave" and "boiling" as methods that ensure the integrity of the w-3 PUFA. CONCLUSION: Hake samples analyzed present an optimal lipid profile. Its content of w-3 PUFA and their properties, make hake fish is distinguished as hearthealthy diets reference.

Introducción: En los últimos 2013s se ha demostrado que los AGPI omega-3 presentan múltiples efectos protectores cardiovasculares. Actualmente, el pescado constituye la principal y la más importante fuente de ácidos grasos Omega-3. Objetivo: Analizar la composición en ácidos grasos en dos especies de merluza, determinar su contenido en ácidos grasos omega-3 y estudiar su aportación en la prevención de enfermedades cardiovasculares. Material y métodos: Se han analizado muestras de dos especies de merluza (Merluccius capensis y Merluccius paradoxus) en su estado natural y congeladas, cocinadas al microondas y muestras hervidas. Se ha estudiado el contenido en humedad, contenido lipídico y el análisis, composición e identificación de ácidos grasos. Resultados: Se observó que el contenido de AGPI w-3 fue mayor que el de AGPI w-6. Los ácidos grasos omega-3 DHA y EPA fueron los más representativos de la familia omega-3, destacando el contenido de DHA en todas lasmuestras analizadas. Asimismo, se ha demostrado la seguridad de los métodos de cocción «microondas¼ y «hervido¼ como métodos que aseguran la integridad de los AGPI w-3. Conclusión: Las muestras de merluza analizadas presentan un óptimo perfil lipídico. Su contenido en AGPI w-3 y sus propiedades, hacen que la merluza se distinga como pescado de referencia en dietas cardiosaludables.

The acute toxicity of chemically and physically dispersed crude oil to key Arctic species under Arctic conditions during the open water season.

The acute toxicity of physically and chemically dispersed crude oil and the dispersant Corexit 9500 were evaluated for key Arctic species. The copepod Calanus glacialis, juvenile Arctic cod (Boreogadus saida), and larval sculpin (Myoxocephalus sp.) were tested under conditions representative of the Beaufort and Chukchi Seas during the ice-free season. The toxicity of 3 water-accommodated fractions (WAF) of Alaska North Slope crude oil was examined with spiked, declining exposures. A dispersant-only test was conducted with the copepod C. glacialis. Each preparation with oil (WAF, breaking wave WAF [BWWAF], and chemically enhanced WAF [CEWAF]) produced distinct suites of hydrocarbon constituents; the total concentrations of oil were lowest in WAF and highest in CEWAF preparations. The relative sensitivity for the different species and age classes was similar within each WAF type. Median lethal concentration values based on total petroleum hydrocarbons ranged from 1.6 mg/L to 4.0 mg/L for WAF and BWWAF treatments and from 22 mg/L to 62 mg/L for CEWAF. For Corexit 9500 exposures, median lethal concentration values ranged from 17 mg/L to 50 mg/L. The differences in the relative toxicity among the accommodated fractions indicated that the majority of petroleum hydrocarbons in the CEWAF are in less acutely toxic forms than the components that dominate the WAF or BWWAF. Further evaluation showed that the parent polycyclic aromatic hydrocarbon compounds, specifically naphthalene, were highly correlated to acute toxicity.

From gelatinous to muscle food chain: rock cod Patagonotothen ramsayi recycles coelenterate and tunicate resources on the Patagonian Shelf.

Stomach contents of 4808 fishes of 20 species caught in the eastern part of the Patagonian Shelf between 1999 and 2012 were analysed to assess dietary contributions of gelatinous plankton resources. Gelatinous plankton occurred in diets of seven species with two species, Patagonotothen ramsayi and Squalus acanthias, having >10% ctenophores in their diet. Consumption of gelatinous plankton was important in P. ramsayi and was strikingly seasonal, with maximum occurrence (up to 46% of non-empty stomachs) in late summer to autumn. Ctenophores were most abundant in P. ramsayi of 25-34 cm total length, L(T) whereas salps were more frequent in larger >35 cm L(T) individuals. In winter to spring, occurrence of gelatinous plankton in diets was minimal, reflecting their overall seasonal abundance in the ocean. The recent increase in abundance of P. ramsayi has enabled the species to recycle a significant proportion of the ecosystem production from gelatinous dead end to the main muscular food chain via seasonal reliance on ctenophores, jellyfish and tunicates. This additional influx of production that has been diverted from the gelatinous food chain favours the increase in abundance of several piscivorous top predators and affects the trophic web structure of the Patagonian Shelf ecosystem.

EROD activity in liver and gills of polar cod (Boreogadus saida) exposed to waterborne and dietary crude oil.

Polar cod Boreogadus saida an indicator species for biomonitoring in the Arctic was exposed to crude oil in waterborne and dietary experiments. Ethoxyresorufin O-deethylase (EROD) activity was measured in liver and gills of polar cod at weeks 0, 2 and 4 of exposure and following 2 weeks of depuration. EROD increased significantly and dose-dependently in both tissues through both exposure routes. Levels were very low in gills compared to liver reflecting the tissue-specific metabolism capacities and tissue-specific response kinetics were also observed. Furthermore, a significant increase of gill EROD was shown in dietary exposed fish, demonstrating a substantial transport of PAHs via the systemic circulation. To conclude, this study gave some preliminary information on the EROD response in terms of levels, dose dependency and timing, in gills of PAH exposed polar cod.

Biomarker responses in polar cod (Boreogadus saida) exposed to dietary crude oil.

Polar cod Boreogadus saida were exposed weekly to two doses of dietary crude oil for 4 weeks followed by 2 weeks of depuration. Administered doses corresponded on average to 4 and 9microgSigmaPAHsg(-1)fishweek(-1). Cytochrome P4501A1 (cyp1a1) and glutathione S-transferase (gst) mRNA expression, ethoxyresorufin O-deethylase (EROD) activity and metabolites in the bile showed strong and dose-dependent inductions at 2 and 4 weeks of exposure. Following 2 weeks depuration, mRNA expression of cyp1a1 and gst and PAH metabolites returned to basal levels while EROD activity and GST activity were still induced in the high oil treatment. The mRNA expressions of antioxidant defense genes (catalase, glutathione peroxidase and cytosolic and mitochondrial superoxide dismutase) did not change significantly during the experiment. Catalase activity was significantly depressed at week 2 in the high oil treatment. We conclude that the cyp1a1 mRNA expression, EROD activities and bile metabolites were the most reliable biomarkers of exposure while gst mRNA expression and GST activity were less sensitive and are considered only as complementary. Antioxidant defenses were poor biomarkers to assess effects of crude oil exposure in polar cod.

Esterase activities and lipid peroxidation levels in offshore commercial species of the NW Mediterranean Sea.

There is a lack of information on monitoring neurotoxicity in offshore commercial species. To help fill this gap, we sampled hake (Merluccius merluccius) and Norway lobster (Nephrops norvegicus) in fishing grounds off the coast of l'Ametlla de Mar (NW Mediterranean) in June 2005 at a depth of 100 m and 400 m. Additionally, at 400 m depth, two other fish species, Micromesistius poutassou and Phycis blennoides were included. Neurotoxicity markers such as Colinesterases (ChEs), namely acethyl- (AChE), butyryl- (BChE), propionyl- (PrChE) and carboxilesterase (CbE) were measured in muscle. Lipid peroxidation (LP), a marker of oxidative damage, was also included. The results are discussed in relation to the animal's sex, size and fishing depth. A comparison of esterases and LP levels between muscle and liver of hake and between muscle and hepatopancreas of Norway Lobster was made. AChE was dominant in muscle and CbE in hepatopancreas. No differences between fish species were seen for AChE. However, N. norvegicus, presented lower levels of ChEs and LP. A size-dependence in ChEs was seen for M. merluccius, with larger animals showing significantly lower activities (p<0.05). Sex-dependence was seen in N. norvegicus for most esterases, except AChE, with males displaying higher activities (p<0.05). A sampling-depth effect was also seen in the crustacea, with animals from 100 m generally presenting lower esterase activities and higher LP levels.