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The effects of crude oil (Szeged-Algyő, Hungary) and oil fractions (F1: rich in aromatics; F2 fraction: free from aromatics) were investigated on liver CYP1A isoenzymes and antioxidant defence system following their i.p. injection into different freshwater fish species: carp ( Cyprinus carpio L.), silver carp ( Hyphothalmichtys molitrix V.), and European eel ( Anquilla anquilla ). A dose of 2 mL kg −1 crude oil enhanced EROD activity 8-fold in carp and only 5-fold in eel after 3 days. Oil fraction F1 caused only a 2-fold induction in EROD activity only in carp, while F2 fraction caused significant inhibition in all three investigated fish species. The antioxidant parameters [lipid peroxidation (LP), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH)] were measured following the treatment. A decrease of 50% in CAT activity was observed after oil treatment. The GSH level enhanced, resulting the protective effects against LP. The same dose of crude oil but a longer duration time resulted in lower CYP1A induction in carp and antioxidant parameters had returned close to control. In all treatments the EROD isoenzymes proved to be more sensitive and the effects of oil treatment showed species to be different. Carp proved to be more sensitive than eel or silver carp.

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The expression pattern of two metallothionein (MT) genes in response to temperature shock and exposure to Cd 2+ was investigated in the brain of common carp ( Cyprinus carpio ), in whole-animal experiments. The changes in the levels of MT-1 and MT-2 mRNA in the olfactory lobe, midbrain and cerebellum were followed by semiquantitative RT-PCR. The inducibility of the two MT genes was brain regionand stressor-specific. Cd 2+ affected mostly the expression of MT-2, while the level of the MT-1 transcript did not change significantly in any of the brain regions examined. Moreover, the MT-2 expression was regulated spatially; MT-2 was induced significantly more strongly in the olfactory lobe than in the cerebellum or midbrain. A sudden temperature drop mainly affected the expression of the MT-1 gene; after 5 h of cold shock, the MT-1 mRNA level was about 25% of the basal value in the cerebellum and the midbrain region. The MT-2 expression did not change significantly during this treatment.

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Heat shock proteins (HSPs) and metallothioneins (MTs) play important roles in protection against environmental stressors. The present study analyzes and compares the regulation of heat shock ( hsp70, hsc70-1 and hsp90α ) and metallothionein (MT-1 and MT-2) genes in the heart of common carp, in response to elevated temperature, cold shock and exposure to several heavy metal ions (As 3+ , Cd 2+ and Cu 2+ ), in whole-animal experiments. Among these metals, arsenate proved to be the most potent inducer of the examined stress genes; the hsp90α and MT-1 mRNA levels were elevated 11- and 10-fold, respectively, after a 24-h exposure. In contrast, Cd 2+ at 10 mg/L had no impact on the expression of hsp90α , and the MT genes also proved to be rather insensitive to Cd 2+ treatment in the heart: only a 2–2.5-fold induction was observed in response to 10 mg/L Cd 2+ . Heat shock resulted in a transient induction of hsp70 (19-fold) and hsp90α (15-fold), while elevated temperature had no effect on the expression of the MTs. Direct cold shock induced hsp70 expression (14-fold), while the hsp90α (26-fold) and MT-2 (2-fold) expressions peaked after the recovery period following a direct cold shock. The five stress genes examined in this study exhibited a unique, tissue-specific basal expression pattern and a characteristic sensitivity to metal treatments and temperature shocks.

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Acta Biologica Hungarica
Authors: Edit Hermesz, Anett P. Gazdag, Ali K. Said, J. Nemcsók, and Magdolna Ábrahám

The expression of two metallothionein (MT) genes was followed in carp (Cyprinus carpio) in vivo during exposure to As and Cu. Changes in the levels of MT-1 and MT-2 mRNA in the liver and kidney were detected by semi-quantitative RT-PCR. The inducibility of the two MT isoforms was tissue- and metal-specific. Regardless of whether As or Cu was applied, the liver was more responsive than the kidney. Copper influenced the expression of both isoforms: the MT-1 and MT-2 mRNA levels increased in both the liver and the kidney in a time- and dose-dependent manner. Arsenic affected mostly the MT-2 expression, while the level of the MT-1 transcript did not change significantly in either organ.

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Heat shock proteins are chaperones that play a pivotal role in controling multiple regulatory pathways such as stress defense, hormone signaling, cell cycle control, cell proliferation and differentiation, and apoptosis. In this study, the expression patterns of four well-known heat shock genes (hsp70, hsc70-1, hsc70-2 and hsp90α) were characterized in the skin, spleen and blood cells of the common carp, under unstressed conditions and after Cd2+ treatment or hypothermia. The examined genes were expressed in a tissue-specific manner: hsc70-2 was expressed constitutively, and was at best only slightly inducible; hsp90α exhibited a high basic expression in all three tissues, whereas hsc70-1 did so only in the blood cells, the expression of hsp70 proved to be below the level of detection in unstressed fish. Cold shock induced the expression of hsp genes in the spleen (hsp90α) and blood cells (hsp70, hsc70-1 and hsp90α), while Cd2+ treatment has no effect on the expression pattern. The highest inducibilities were detected in the skin: for hsp70 an induction of at least 20-fold after cadmium exposure, for hsc70-1 of at least 30-fold and for hsp90α of 3-fold after hypothermia.

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Humics and pesticides are present in aquatic environment and the toxicological consequences of their chemical interaction is well studied. However, data concerning the mechanism of the biochemical action of humic-pesticide combinations are scarce, especially in vertebrates. Thus we have chosen to study the in vivo effects of the plant polyphenolic tannic acid and the pyrethroid insecticide deltamethrin [Decis] alone or in combination on hepatic xenobiotic-metabolizing enzyme activities and the associated redox-parameters in carp, as the complex assessment of these systems are regarded to serve as a relevant biomarker of environmental pollution. Stress effects and tissue damage were followed by determination of the plasma glucose level, the activities of plasma transaminases, and by electron microscopy. Tannic acid alone exerted weak prooxidant effect due to its marked antioxidant enzyme inhibitory activity. Deltamethrin, applied in a very low dose, induced oxyradical production in fish via activation of cytochrome P450 isozymes. This effect was promoted by the antioxidant enzyme inhibitory action of tannic acid, when the two chemicals were combined; however, the ultrastructural damage of the hepatocytes was reduced by the common cytoprotective capacity of the phenolic. Numerous humics are known to alter the toxicity of pesticides and their influence depends on their type and concentration. Therefore, our work taken together with other comparative studies may contribute to the assessment of the impact of humics in nature, especially in case of environmental pollution.

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