The aim of the present work was to compare the distribution of selected metals in tissues of several fish species caught in the Věstonice reservoir. The hygienic quality of fish meat was assessed with respect to the mercury concentration. A total of 35 fish of the following species were caught: carp (Cyprinus carpio), bream (Abramis brama), asp (Aspius aspius), pikeperch (Sander lucioperca) and pike (Esox lucius). Samples of muscle, liver (hepatopancreas), kidney, gonads and gills were analyzed. Hg, Pb, Cd, Cu, Zn and Cr concentrations in fish tissues were determined by the AAS. The results showed that different metals differ in their affinity to different fish tissues (e.g. Cu -liver, Cd -kidney). Mercury concentrations along the food chain increase, i.e. higher mercury concentrations are found in predatory fish. Contrary to mercury, cadmium and lead concentrations do not show any increases along the fish part of food chain in surface water ecosystems. In predatory fish, lower concentrations of these metals were found than in nonpredatory fish species. Differences in concentrations between ovaria and testes were found only in Cu and Zn. To evaluate possible health risks of mercury concentrations for consumers, the risk index was calculated and maximum admissible amounts of muscle meat for consumption were determined. The results confirmed good hygienic quality of market-ready fish from the Věstonice reservoir. Predatory fish, non-predatory fish, heavy metals, AAS, risk indexThe rising living standards of human population take their toll in increasing loads to the environment with various contaminating substances that occur naturally at very low concentrations, or do not naturally occur at all. Besides metal manufacturing and processing, the sources of environmental metal contamination include industrial waste products, the burning of fossil fuels, and the use of metals by consumers. The increase in metal concentrations in the environment is further enhanced by their poor degradability resulting in metal accumulation in the soil, water sediments and the food chain (Svobodová et al. 1987).As the final link of the food chain in the aquatic environment, fish are an important indicator of contamination by a number of substances, including metals (Svobodová et al. 1996). Moreover, toxic metal concentrations in fish are monitored also in terms of food safety (Svobodová et al. 2004). First and foremost, the most closely monitored potentially toxic metals include mercury followed by cadmium and lead. In recent years, food safety has been a priority in EU member states. Hence, the large number of regulations targeting veterinary food hygiene that are being adopted mainly by the European Food Safety Authority (EFSA) and other organisations. At present, hygienic limits are determined by the highest acceptable levels of contaminants in foodstuffs in the Commission Regulation 1881/2006/EC as amended and Decrees 68/2005 Sb. and 305/2004 Sb. of the Ministry of Health. As far as fish as food animals are concerned, the m...

The aim of the study was to evaluate mercury contamination at twelve outlet sites of rivers in the Czech Republic (Labe, Ohře, Vltava, Berounka, Sázava, Otava, Lužnice, Svratka, Dyje, Morava and Odra). As an indicator, we used muscle tissue of the chub (Leuciscus cephalus) caught at selected sites in 2007. A total of 96 fish were examined. Total mercury was determined by atomic absorption spectrophotometry using the AMA 254 analyzer and methylmercury was determined by gas chromatography with electron-capture detection. Total mercury (THg) and methylmercury (MeHg) concentrations ranged 0.039-0.384 mg·kg -1 fresh weight and 0.033-0.362 mg·kg -1 fresh weight, respectively. Mercury bound in methylmercury (Hg Me ) made up on average about 82.2% of total mercury. The highest mercury concentrations were found in fish from Obříství, a site on Labe (THg 0.263 ± 0.086 mg·kg -1 ; MeHg 0.256 ± 0.084 mg·kg -1 ). Mercury concentrations in fish from rivers that cross the borders of the Czech Republic (Labe, Odra and Morava) were low. The Czech Republic therefore does not contribute significantly to river pollution outside its national borders. Hazard indices of the sites monitored were well below 1, and reached 1.365 only in Obříství on Labe for fisherman's family members (i.e. in the case of annual consumption of 10 kg fish). This indicates possible hazards involved in eating meat of fish caught in that location. Based on PTWI for methylmercury, the maximum amount of fish meat allowed for consumption per week was calculated. The site with the lowest value was Obříství on Labe (0.44 kg). The results of this study present a partial contribution to health risk assessment on the major rivers in Czech Republic.Leuciscus cephalus, methylmercury/mercury ratio, THg, MeHg, hazard index, PTWI

Kenšová R., Kružíková K., Svobodová Z. (2012): Mercury speciation and safety of fish from important fishing locations. Czech J. Food Sci., 30: 276-284.The aim of the study was to describe the distribution of total mercury in the tissues of fish originating from important Czech fishing locations and to determine the level of methylmercury as a percentage of total mercury (Hg speciation). At six important fishing locations a total of 144 fishes of 13 species were caught and analysed. Samples of muscle, liver, gonads and scales were analysed for total mercury and in the case of muscles for methylmercury concentrations. Total mercury was determined by AAS using an AMA 254 analyser, and methylmercury determination was performed by GC/ECD using a GC-2010A chromatograph. Total mercury concentrations in muscle and other tissues of all the fish from all fishing locations were below 0.5 mg/kg, with the exception of 6 asps (Aspius aspius). A significant (P < 0.05) correlation was found between the total mercury concentrations in scales and other tissues. Methylmercury made up about 46-100% of total mercury in muscle. The overall results confirmed the good hygienic quality of fish from important Czech fishing locations.

The aim of this study was to synthesize cadmium telluride nanoparticles (CdTe NPs) modified apoferritin, and examine if apoferritin is able to accommodate CdTe NPs.

Kružíková K., Blahová J., Kenšová R., Jurčíková J., Hypr D., Svobodová Z. (2009): Mercury and methylmercury content in chub from the Svitava and Svratka Rivers at agglomeration Brno. Czech J. Food Sci., 27: 470-476.The aim of our study was to determine the total mercury and methylmercury contents in the muscle of indicator fish, to determine the total mercury contents in the sediment, and to evaluate the health risks associated with fish contamination. Chub (leuciscus cephalus L.) were caught in seven localities on the Svratka and Svitava Rivers in the Brno agglomeration in 2007. The total mercury content was determined by atomic absorption spectrophotometry using an AMA 245 analyser. Methylmercury levels were determined by gas chromatography (using electron-capture detector) after acid digestion and extraction with toluene. The highest levels of total mercury and methylmercury contamination in the fish muscle (0.18 ± 0.09 mg/kg and 0.16 ± 0.09 mg/kg, respectively) were found at the Rajhradice site (the Svratka River, under the Brno city), whereas the lowest contents of mercury and methylmercury (0.08 ± 0.02 mg/kg and 0.04 ± 0.03 mg/kg) were detected at the Modřice site (the Svratka River). Total mercury content in the sediment ranged from 0.06 mg/kg to 1.38 mg/kg, the higher value having been detected in the sediment from the Svratka River at the Rajhradice site above the confluence with the Svitava River. The lowest content was discovered at Kníničky (the Svatka River). The hazard indices calculated for the selected localities showed no health risk to the common consumer or to the fishermen and their families.

The aims of the study were to determine total mercury concentrations in “rainbow trout Oncorhynchus mykiss (Walbaum)” at their embryo-larval and juvenile stages and to assess mercury concentration dynamics in individual tissues. Samples of rainbow trout were collected at two-month intervals over a period of 18 months (one stock production cycle) at the Velká Losenice trout farm. Feedstuff samples were collected at the same time and analyzed for mercury concentrations. Tissue mercury concentrations were determined in muscle, liver, and kidneys. Analyses were performed using the AMA 254 atomic absorption spectrophotometer. The lowest mercury concentration was found in 14-day-old embryos (hard roe), and the highest concentrations in muscle tissue, liver, and kidneys at the end of monitoring, that is, in rainbow trout aged 18 months. The amount of mercury in feedstuffs showed an increasing trend and ranged between 0.0126 and 0.0859 mgkg−1. A significant effect (P < 0.001) of mercury intake on mercury concentrations in muscle tissue, liver, and kidneys was demonstrated. Muscle mercury concentrations in 18-month-old market-ready rainbow trout of 0.128 ± 0.048 mgkg−1 met the criteria for fish meat hygiene.

Peptide-peptide interactions are crucial in the living cell as they lead to the formation of the numerous types of complexes. In this study, synthetic peptides containing 11 of cysteines (α-domain of metallothionein (MT)) and sialic acid binding region (130-loop of hemagglutinin (HA)) were employed. The aim of the experiment was studying the interactions between MT and HA-derived peptides. For this purpose, fragments were tagged with cysteines at C-terminal part to serve as ligand sites for PbS and CuS quantum dots (QDs), and therefore these conjugates can be traced and quantified during wide spectrum of methods. As a platform for interaction, γ-Fe2O3 paramagnetic particles modified with tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane (hydrodynamic diameter 30-40 nm) were utilized and MT/HA interactions were examined using multi-instrumental approach including electrochemistry, electrophoretic methods, and MALDI-TOF/TOF mass spectrometry. It was found that peptides enter mutual creation of complexes, which are based on some of nonbonded interactions. The higher willingness to interact was observed in MT-derived peptides toward immobilized HA. Finally, we designed and manufactured flow-through electrochemical 3D printed device (reservoir volume 150 μL) and utilized it for automated analysis of the HA/MT metal labels. Under the optimal conditions, (deposition time and flow rate 80 s and 1.6 mL/min for CuS and 120 s and 1.6 mL/min PbS, respectively), the results of peptide-conjugated QDs were comparable with atomic absorption spectrometry.

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