Hepatic biomarker responses to organic contaminants in feral chub (Leuciscus cephalus)--laboratory characterization and field study in the Sava River, Croatia

Biochemical responses and antioxidant defense mechanisms in Channa Striatus exposed to Bisphenol S

Bisphenol S (BPS), a BPA analog and a safer alternative, is utilized in a diverse range of industrial applications, such as making polycarbonate plastics, epoxy resins, thermal receipt papers, and currency bills. Recently, the increased use of BPS in containers and packages for daily life has been interrogated due to its identical chemical structure and probable endocrine-disrupting actions as BPA has. The present study aimed to evaluate the alterations in biochemical indices and antioxidant enzymes as certain indicators of the endocrine-disrupting effect of BPS in Channa striatus, a freshwater fish. BPS-exposed fish species were subjected to three sub-lethal concentrations of BPS (1, 4, and 12 ppm) and observed after an interval of 7 and 21 days. Exposure to BPS caused a reduction in the level of protein in muscle, gonads and the liver due to an impairment of protein synthesis. Levels of cholesterol in the muscle, gonads, and liver of BPS-exposed fish were found to be decreased after treatment, indicating either an inhibition of cholesterol biosynthesis in the liver or reduced absorption of dietary cholesterol. The levels of antioxidant enzymes such as superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase showed remarkable increases, while the activity of glutathione S-transferase decreased considerably, indicating the antioxidant defense mechanism to counteract the oxidative stress induced by BPS. Moreover, a significant increase was noted in the level of lipid peroxidation products, like malondialdehyde and conjugate diene, which represent biomarkers of oxidative stress. The histoarchitecture changes were also observed in the liver, muscle and gonads of BPS-treated fish species. The present study showed that sub-lethal exposure to BPS significantly influenced the activities of these enzymes and peroxidation byproducts. From this study, it is concluded that BPS-caused toxic effects in fish species lead to an imbalance in the antioxidant defense system. It is clearly indicated that BPS toxicity could lead to susceptible oxidative stress in various tissues and could damage vital organs.

Oxidative stress responses of a freshwater fish, Labeo rohita, to a xenobiotic, bisphenol S

Bisphenol S (BPS) is an organic chemical that has been used as a substitute for bisphenol A (BPA) in making polycarbonate plastics, epoxy resins, thermal receipt papers, and currency bills, as BPA has been reported to have dreadful effects on the living system. From this view point, the present study investigates whether BPS has the same or rather more toxic effects like BPA or not. Limited studies were carried out on the effect of BPS on fish. The hepatic antioxidant enzymes such as superoxide dismutase, catalase, glutathione S-transferase, glutathione reductase, and glutathione peroxidase (GPx), along with the nonenzymatic antioxidant, glutathione, in a freshwater fish, Labeo rohita, were selected as biomarkers. The results revealed that the sublethal exposure of BPS significantly influenced the activities of these biomarkers. Lipid peroxidation (LPO) products such as malondialdehyde and conjugate diene levels were also altered by the exposure. The alteration in the levels of antioxidants and LPO products after BPS exposure clearly showed that the fish experienced oxidative stress. Furthermore, the current study showed that BPS is a pollutant with oxidative potential by disrupting the antioxidant enzymes.

Experience Gained from Ecotoxicological Studies in the Seine River and Its Drainage Basin Over the Last Decade: Applicative Examples and Research Perspectives

The Seine River and its drainage basin are recognised as one of the most urbanised water systems in France. This chapter gathers typical applications of complementary ecotoxicological tools that were used in PIREN-Seine programmes for a decade to reflect the Seine River contamination as well as its biological repercussions on organisms. Ecotoxicological studies focused on both (1) specific bioassays and (2) (sub)-individual biological responses (i.e. biomarkers) measured in diverse taxa (i.e. crustaceans, mussels and fishes) representative of the trophic network. Experience gained from these studies made it possible to establish reference and threshold values for numerous biological endpoints. They now can be combined with chemical measurements within integrated models (i.e. the Weight of Evidence [WOE] approach) generating a global index of waterbody pollution. These biological endpoints today appear sufficiently relevant and mature to be proposed to water stakeholders as efficient tools to support environmental management strategies.

Multiresidue Methods for the Determination of Organic Micropollutants and Their Metabolites in Fish Matrices

Two analytical methods were developed for the determination of 48 organic compounds and 20 of their main by-products in fish matrices. The targeted compounds belong to various chemical classes of metabolizable (phthalates, polycyclic aromatic hydrocarbons, insecticides [pyrethroids and N,N-diethyl-meta-toluamide]) and legacy (organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers) pollutants. Analyses were performed by gas and liquid chromatography-tandem mass spectrometry in multiple reaction monitoring (MRM) and dynamic MRM, respectively. Method performances were satisfactory, with results meeting the validation criteria because they achieved good linearity responses, recovery, precision, and accuracy for most of the 68 investigated compounds. The methods were then applied on 3 feral chub (Squalius cephalus) collected from the Marne hydrographic network (France). Twenty-six parent compounds and 5 metabolites were systematically detected in fish matrices, with substantial concentration variability within and among individuals. Phthalates and pyrethroids accounted for most of the pollutant load. Metabolite concentrations in liver samples exceeded those of parent molecules in fish muscle. The present study presents 2 reliable methods for the determination of a wide range of contaminants and underlines the importance of metabolite analysis for a more comprehensive understanding of pollutant bioaccumulation and fate in aquatic organisms. Environ Toxicol Chem 2019;38:1866-1878. © 2019 SETAC.

Effects of mine tailing and mixed contamination on metals, trace elements accumulation and histopathology of the chub (Squalius cephalus) tissues: Evidence from three differently contaminated sites in Serbia

Chub (Squalius cephalus) specimens were collected in Korenita River seven months after spillover from the waste water of antimony mine tailing pond and compared with chub living in Kruščica reservoir (intended for water supply) and Međuvršje reservoir (influenced by intense emission of industrial, urban and rural wastewater). Concentrations of 15 elements (Al, As, B, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Si, Sr, Zn) were determined in muscle, liver and gills of chub by inductively coupled plasma optical spectrometry (ICP-OES) and histopathological alterations in liver and gills were assessed. Chub specimens from Korenita River had higher concentrations of As, Ba and Pb in all three investigated tissues as well as higher total histopathological index values than chub from reservoirs. Specimens from Međuvršje reservoir were characterized by higher values for concentrations of Cu and Si in muscle tissue and higher values for regressive histopathological alterations in gills. Individuals of chub from Kruščica reservoir had the highest concentrations of Fe in liver, Hg in muscle and Sr and Zn in muscle while gills had the lowest value of total histopathological index. The results from the present study showed higher level of histopathological alterations as a result of mine tailing accident. As a result of mixed contamination on the Međuvršje site, histopathological index values of gills were in line with the index value from Korenita River. Increased values for Fe and Sr in chub tissue from Kruščica reservoir could be explained by geological structure of the site which is characterized by magmatic rock rich in Cu, Fe and Ni as well as dominant carbonate sediment complex of marine origin with increased level of Sr.

Evaluation of Genotoxic Pressure along the Sava River

In this study we have performed a comprehensive genotoxicological survey along the 900 rkm of the Sava River. In total, 12 sites were chosen in compliance with the goals of GLOBAQUA project dealing with the effects of multiple stressors on biodiversity and functioning of aquatic ecosystems. The genotoxic potential was assessed using a complex battery of bioassays performed in prokaryotes and aquatic eukaryotes (freshwater fish). Battery comprised evaluation of mutagenicity by SOS/umuC test in Salmonella typhimurium TA1535/pSK1002. The level of DNA damage as a biomarker of exposure (comet assay) and biomarker of effect (micronucleus assay) and the level of oxidative stress as well (Fpg—modified comet assay) was studied in blood cells of bleak and spirlin (Alburnus alburnus/Alburnoides bipunctatus respectively). Result indicated differential sensitivity of applied bioassays in detection of genotoxic pressure. The standard and Fpg—modified comet assay showed higher potential in differentiation of the sites based on genotoxic potential in comparison with micronucleus assay and SOS/umuC test. Our data represent snapshot of the current status of the river which indicates the presence of genotoxic potential along the river which can be traced to the deterioration of quality of the Sava River by communal and industrial wastewaters. The major highlight of the study is that we have provided complex set of data obtained from a single source (homogeneity of analyses for all samples).

Assessment of status of three water bodies in Serbia based on tissue metal and metalloid concentration (ICP-OES) and genotoxicity (comet assay)

Metals and metalloids are natural components of the biosphere, which are not produced per se by human beings, but whose form and distribution can be affected by human activities. Like all substances, they are a contaminant if present in excess compared to background levels and/or in a form that would not normally occur in the environment. Samples of liver, gills, gonads and muscle from European chub, Squalius cephalus, were analyzed for Al, As, B, Ba, Cr, Cu, Fe, Hg, Mn, Mo, Sr and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) to highlight the importance of tissue selection in monitoring research. The comet assay or single cell gel electrophoresis (SCGE) was selected as an in vivo genotoxicity assay, a rapid and sensitive method for measuring genotoxic effects in blood, liver and gills of the European chub. Microscopic images of comets were scored using Comet IV Computer Software (Perceptive Instruments, UK). The objective of our study was to investigate two reservoirs, Zlatar and Garasi, and one river, Pestan by: (i) determining and comparing metal and metalloid concentrations in sediment, water and tissues of European chub: liver, gills, muscle and gonads (ii) comparing these findings with genotoxicity of water expressed through DNA damage of fish tissues. A clear link between the level of metals in water, sediment and tissues and between metal and genotoxicity levels at examined sites was not found. This suggests that other xenobiotics (possibly the organic compounds), contribute to DNA damage.

Chemical and histological comparisons between Brevoortia sp. (menhaden) collected in fall 2010 from Barataria Bay, LA and Delaware Bay, NJ following the DeepWater Horizon (DWH) oil spill

Body burdens of PAHs were compared to histological effects in menhaden (Family: Clupeidae, Genus: Brevoortia) collected in fall 2010 from Barataria Bay, LA (BBLA) and Delaware Bay, NJ (DBNJ). Barataria Bay was heavily oiled during the DeepWater Horizon (DWH) oil spill, while Delaware Bay although urbanized had no reported recent oil spills. GCMS analyses of pre-spill 2009, BBLA and DBNJ fish found predominantly C2/C3 phenanthrene (1.28-6.52 ng/mg). However, BBLA also contained five higher molecular weight PAHs (0.06-0.34 ng/mg DW). Fluorescent aromatic compound spectroscopy (FACS) of gastrointestinal (GI) tract tissue showed statistically higher levels of hydroxypyrene-like PAHs in DBNJ than BBLA fish. Histopathologic lesions were more prevalent in BBLA than DBNJ fish. The lesion prevalence (gill, trunk kidney, epidermis, stomach) in the BBLA menhaden were significantly higher and more severe than observed in the DBNJ menhaden. Reversible lesions included gill lamellar hyperplasia, adhesions, edema, and epidermal hyperplasia. The increased pigmented macrophage centers were indicative of activated macrophages responding to connective tissue damage or other antigens. The liver hepatic necrosis and renal tissue mineralization may well have undergone repair, but damage to the kidney nephrons and hepatic/biliary regions of the liver would be slower to resolve and apparently remained after elimination of PAHs. Therefore, a direct cause and effect between DWH oil spill and increased lesion prevalence in BBLA menhaden could not be established.

Pomphorhynchus laevis (Acanthocephala) from the Sava River basin: New insights into strain formation, mtDNA-like sequences and dynamics of infection

Here we report the genetic variability and presence of mtDNA-like sequences of Pomphorhynchus laevis from the chub, Squalius cephalus, caught at the sampling sites along the Sava River and its tributary the Sutla River in Croatia. Sequences of the cytochrome c oxidase subunit 1 (COI) gene of the recovered P. laevis specimens were used for haplotype network construction and phylogenetic analysis. These analyses showed that some specimens contained mitochondrial-like sequences, and they uncovered the existence of a Sava River basin strain different from known strains of P. laevis. This is the first time that P. laevis has been shown to contain mtDNA-like sequences, suggesting the need to exercise caution during COI analyses of P. laevis using universal primers. Highly conserved sequences of two nuclear markers, the ITS region and 18S rRNA, were not helpful for understanding genetic variability or differentiating strains. Furthermore, analysis of the dynamics of P. laevis infections in S. cephalus from the Sava and Sutla Rivers showed decreased prevalence and abundance at sites with inferior water quality, positive association of parasite abundance with fish size, and no clear association of parasite abundance with fish condition index or sex.

Relevance of biotic parameters in the assessment of the spatial distribution of gastrointestinal metal and protein levels during spawning period of European chub (Squalius cephalus L.)

The present field study, conducted during the spawning period (April/May) of European chub (Squalius cephalus L.) from the Sava River in Croatia, indicates that seasonal changes of fish physiological state might cause variability in gastrointestinal metal (Cd, Cu, Fe, Mn and Zn), total cytosolic protein and metallothionein (MT) levels. During the period of fish spawning and increased metabolic activity, a significant relationship with chub hepatosomatic index was evident for Fe and Mn in gastrointestinal tissue (r = 0.35 and 0.26, respectively) and in cytosolic fraction (r = 0.32 and 0.41, respectively) and for Zn and Fe in the gut content (r = 0.36 and 0.31, respectively). Total cytosolic protein and MT concentrations followed the same spatial distribution as Fe and Mn in all gastrointestinal fractions and as Zn in the sub-cellular fractions, with higher levels at upstream locations. Due to the role of essential metals in metabolic processes and gonad development, increased feeding and spawning activity in April/May resulted in higher gastrointestinal essential metal (Fe, Mn and Zn) and MT concentrations, which probably follow an increase in Zn concentrations, known as the primary MT inducer. Therefore, biotic factors should be considered as important confounding factors in metal exposure assessment, while their influence on gastrointestinal metal and protein levels should be interpreted depending on the season studied.

Variability in DNA damage of chub (Squalius cephalus L.) blood, gill and liver cells during the annual cycle

In this work the genotoxic potential of water in three localities in Serbia, which differ by the nature and degree of pollution, was determined in tissues of European chub (Squalius cephalus L.) on monthly basis over the 2011/2012 year season using the alkaline comet assay. Specimen samples of chub were taken from Special Nature Reserve "Uvac", as control site, and Pestan and Beljanica Rivers, as polluted sites at Kolubara basin, surrounded with coal mines. Three tissues, blood, gills and liver were used for assessing the level of DNA damage. Analysis was done by software (Comet Assay IV). The control site at Reserve "Uvac" showed the lowest DNA damage values for all three tissues compared to Pestan and Beljanica. Blood has the lowest level of DNA damage in comparison with liver and gills. Decreased damage for all three tissues was observed at summer, while during the spring and autumn damage increased.

The responses of the hepatosomatic index (HSI), 7-ethoxyresorufin-O-deethylase (EROD) activity and glutathione-S-transferase (GST) activity in sea bass (Dicentrarchus labrax, Linnaeus 1758) caged at a polluted site: implications for their use in environmental risk assessment

The present study investigates the response of three hepatic biomarkers in adult sea bass (Dicentrarchus labrax, Linnaeus 1758) caged at a wastewater outlet of an oil refinery with fish caged at a pristine site used as controls. The biomarkers that were investigated were the hepatosomatic index (HSI), 7-ethoxyresorufin-O-deethylase (EROD) activity and glutathione-S-transferase (GST) activity. In addition, we have measured the levels of polycyclic aromatic hydrocarbons (PAHs) and selected heavy metals (lead, cadmium, mercury, copper and zinc) in sediment samples at the polluted site. Although the polluted site had high environmental levels of PAHs and heavy metals, there was no difference in hepatic EROD activity and HSI between fish caged at the polluted site and controls. On the other hand, GST activity was significantly lower in fish caged at the polluted site compared to controls. Our results point out that the studied biomarkers have limited use in environmental risk assessment studies, at least when caged adult sea bass is used as the sentinel species and complex toxicant mixtures are involved.

Multielement analysis in the fish hepatic cytosol as a screening tool in the monitoring of natural waters

The possibility of direct measurement of trace elements in hepatic cytosol of European chub (Squalius cephalus) by high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) after cytosol dilution with Milli-Q water and subsequent acidification was investigated. Due to low detection limits of this procedure, determination of 13 elements (As, Cd, Co, Cu, Fe, Mn, Mo, Pb, Sb, Sn, Sr, V and Zn) was possible in the chub hepatic cytosol, exhibiting excellent measurement repeatability in duplicates. Some of these elements were also measured by HR ICP-MS in acid digested cytosols (Cd, Co, Cu, Fe, Mn, Mo, Sr, V and Zn). Good agreement of the results obtained after sample dilution and sample digestion indicated that complex organic matrix of hepatic cytosol did not affect measurement reliability. Cytosolic concentrations of 13 trace elements in the chub liver were quantified in the following order: Fe, Zn>Cu>Mn>Mo>Sr, V, Cd>Co>As, Pb>Sn>Sb. Unlike Cd, Cu, Fe, Mn and Zn for which the cytosolic concentrations were previously reported after measurement by AAS, cytosolic concentrations of eight additional trace elements characteristic for the liver of chubs inhabiting the low contaminated river water were reported here for the first time (in nanogrammes per gramme)-Mo, 136.8-183.6; Sr, 32.7-63.0; V, 17.5-69.0; Co, 24.3-30.7; As, 9.9-29.5; Pb, 5.8-35.6; Sn, 5.5-12.4; and Sb, 0.9-2.6. The simultaneous measurement of large number of trace elements in the cytosolic fractions of fish tissues, which comprise potentially metal-sensitive sub-cellular pools, could be beneficial as a screening tool in the monitoring of natural waters, because it would enable timely recognition of increased fish exposure to metals.

Prioritisation of organic contaminants in a river basin using chemical analyses and bioassays

Region-specific contaminant prioritisation is an important prerequisite for sustainable and cost-effective monitoring due to the high number of different contaminants that may be present. Surface water and sediment samples from the Sava River, Croatia, were collected at four locations covering a 150-km-long river section characterised by well-defined pollution gradients. Analysis of contaminant profiles along the pollution gradients was performed by combining toxicity screening using a battery of small-scale or in vitro bioassays, which covered different modes of action, with detailed chemical characterisation based on gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). A large number of contaminants, belonging to different toxicant classes, were identified in both analysed matrices. Analyses of water samples showed that contaminants having polar character occurred in the highest concentrations, while in sediments, contributions from both non-polar and amphiphilic contaminants should be taken into account. Estimated contributions of individual contaminant classes to the overall toxicity indicated that, besides the classical pollutants, a number of emerging contaminants, including surfactants, pharmaceuticals, personal care products and plasticizers, should be taken into consideration in future monitoring activities. This work demonstrates the importance of the integrated chemical and bioanalytical approach for a systematic region-specific pollutant prioritisation. Finally, the results presented in this study confirm that hazard assessment in complex environmental matrices should be directed towards identification of key pollutants, rather than focusing on a priori selected contaminants alone.

Reciprocal inhibiting interactive mechanism between the estrogen receptor and aryl hydrocarbon receptor signaling pathways in goldfish (Carassius auratus) exposed to 17β-estradiol and benzo[a]pyrene

In the aquatic environment, both the estrogen receptor (ER) and aryl hydrocarbon receptor (AhR) responses are established biomarkers for assessing exposure to pollutants. These receptor responses can also be affected by the presence of other classes of pollutants and may result in misinterpretation of existing pollution. In this study, we investigated the interaction between ER-vitellogenin (VTG) and AhR-cytochrome P450 1A (CYP1A) signaling pathways in goldfish (Carassius auratus) after 10 days exposure to pollutants. 17β-Estradiol (E(2)) and benzo[a]pyrene (BaP) were selected as the ER and AhR agonists, respectively. The messenger RNA (mRNA) expression of ER-VTG and AhR-CYP1A in liver was determined using quantitative real-time polymerase chain reaction (QRT-PCR). VTG, endogenous E(2) and 7-ethoxyresorufin-O-deethylase (EROD) were also studied. Exposure to E(2) and BaP alone significantly induced the gene expression of ERα-VTG and AhR2-CYP1A, respectively. Moreover, the obvious expression of related proteins was also observed. However, these inductions were significantly reduced after combined exposure to E(2) and lower concentrations of BaP (20 and 50 μg/L), indicative of a reciprocal inhibiting ER-AhR interaction. However, high concentrations (100 μg/L) of BaP did not affect the E(2)-induced gene expression. Changes in VTG protein were in accordance with the expression of VTG mRNA, and more VTG protein was observed in liver than in serum. The induced endogenous E(2) levels were suppressed by the presence of BaP. While the gene expression of CYP1A showed a concentration-dependent increase, EROD induction exhibited a bell-shaped concentration-response curve. Taken together, these results demonstrate a reciprocal inhibiting mode of ER-AhR interactions and may lead to a possible underestimation of actual exposure.

Detection of mutagens and BaPMO inducers in river water using the Blue Cotton adsorption technique

Induction of Mixed Function Oxidase (MFO) activity and bioactivation potential were measured in experimental carp and in native fish species from two rivers with different pollution level (Sava and Mrežnica). The experimental carp were intraperitoneally exposed to various water volume equivalents of Blue Cotton extracts from both rivers. The induction of MFO measured as a Benzo(a)pyrene monooxygenase (BaPMO) activity was increased up to 9.3-fold in experimental carp and up to 11.3-fold in native fish from Sava River, whereas the values from Mrežnica River showed only a slight increase when compared with the control (highest increase of 1.8-fold in nose carp). Accordingly, bioactivation potential using modified Ames test was higher in both experiments with Sava River. Both measured parameters in experimental carp increased in a dose-dependent manner in accordance to river volume equivalents. Different induction potential of native fish species comparable between two rivers confirmed the known possibility of their usage in biomonitoring studies. These results give qualitatively a new support to the idea of using Blue Cotton extraction technique combined with induction of MFO activity and Ames test in fish as a good biomarker for assessing risk of exposure to mutagens/carcinogens such as Polycyclic Aromatic Hydrocarbons (PAHs), especially due to the simplicity and cost-effectiveness of these methods.

Chemical indicators of anthropogenic impacts in sediments of the pristine karst lakes

The anthropogenic impact on the pristine karst lakes was investigated using combination of specific parameters, including multielemental analysis of major inorganic constituents (Al, K, Fe) and trace metals (Li, Ag, Cd, Sn, Pb, Bi, Cr, Co, Ni, Cu, Zn and Sb), polycyclic aromatic hydrocarbons (PAHs) and anionic surfactants of linear alkylbenzene sulfonate (LAS) type. The study was performed in the Plitvice Lakes National Park, situated in a sparsely populated area of the northwestern Dinarides, central Croatia. Dated cores of recent sediments from the two biggest lakes, Lake Prosce and Lake Kozjak, were analysed for the selected contaminants using highly specific methods, involving inductively coupled plasma mass spectrometry (ICP/MS), gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). The concentration of inorganic constituents reflected primarily the geological background of the area as well as geomorphological and geochemical characteristics of the Plitvice Lakes. Due to the higher terrigenous input, the concentration of all elements was significantly higher in the Lake Prosce. The concentration of toxic metals was relatively low in both lakes, except for Cd (>1 mg kg(-1)) and Pb (up to 40 mg kg(-1)). The vertical profiles of these metals suggested that elevated concentrations of Cd were of natural origin, derived from the erosion of the Jurassic dolomite bedrock, while Pb was predominately of recent anthropogenic origin. A similar distribution pattern, suggesting the same prevailing mechanism of input, was observed for pyrolytic PAHs. The characteristic diagnostic PAH ratios revealed that higher PAHs prevailingly originated from the combustion of biomass and fossil fuels. LAS, which represent highly specific indicators of untreated wastewaters, were found in rather high concentrations in the recent sediment layers (up to 4.7 mg kg(-1)), suggesting that contaminated household and hotel wastewaters reach the Lakes, very probably by leaking through the porous karst rocks.

Biochemical markers for the assessment of aquatic environment contamination

The need for assessment of aquatic ecosystem contamination and of its impact on water dwelling organisms was developed in response to rising aquatic environmental pollution. In this field study, liver enzymes of phase I and phase II of xenobiotic transformation, namely cytochrome P450, ethoxyresorufin-O-deethylase, glutathione-S-transferase and tripeptide glutathione were used to assess the contamination of the aquatic environment at different rivers in the Czech Republic. The indicator species selected was the male chub (Leuciscus cephalus L.) and male brown trout (Salmo trutta fario). Chemical analyses included also the assessment of the most important inductors of previously mentioned biochemical markers. The major inductors of monitored biomarkers are industrial contaminants which belong to a large group of organic pollutants (PCB, PAH, PCDD/F, DDT, HCH, HCB and OCS), persistent in the environment. Four different groups of river basins were assessed: the River Tichá Orlice and its tributary the Kralický brook; important tributaries of the River Elbe (the rivers Orlice, Chrudimka, Cidlina, Jizera, Vltava, Ohře and Bílina); major rivers in the Czech Republic (the rivers Lužnice, Otava, Sázava, Berounka, Vltava, Labe, Ohře, Svratka, Dyje, Morava and Odra) and the River Vltava. The use of the biochemical markers together with chemical analyses seems to be an effective way to monitor the quality of aquatic environment.

DNA integrity of chub erythrocytes (Squalius cephalus L.) as an indicator of pollution-related genotoxicity in the River Sava

An alkaline comet assay and a micronucleus test were carried out on erythrocytes of the European chub, Squalius cephalus L., collected in spring and autumn in 2005 and 2006 at three sampling sites in River Sava, near Zagreb, Croatia. The results of comet assay showed the lowest genotoxic influence at the least polluted site, while higher DNA damage was observed at the polluted sites. Although the basal levels of DNA damage were elevated, a clear gradation of DNA damage was found due to pollution intensity in all sampling periods. The lowest cytogenetic damage as revealed by the micronucleus test (MNT) was observed as well at the least polluted site. High variations in MN frequency were observed between sampling periods, although the number of micronucleated erythrocytes was consistently the highest one at the polluted site. The comet assay as a biomarker of genotoxic effect exhibited higher sensitivity in discriminating the genotoxic capacity of studied polluted sites while the MNT was less sensitive. However, both tests should be used together in biomonitoring studies because they can reveal different aspects of DNA damage; comet assay, the early event of genotoxic exposure, and MNT, its final result as a mutagenic potential.

Fish hepatic glutathione-S-transferase activity is affected by the cestode parasites Schistocephalus solidus and Ligula intestinalis : evidence from field and laboratory studies

The activity of hepatic glutathione-S-transferase (GST) was analysed in 3 different fish species with respect to fish sex and infection with parasites. In both sexes of laboratory bred three-spined sticklebacks (Gasterosteus aculeatus)experimentally infected withSchistocephalus solidus(Cestoda), a significantly lower GST-activity was found for infected fish compared to control. After field sampling of roach (Rutilus rutilus) from Lake Müggelsee (MS) and the Reservoir Listertalsperre (LTS), the GST-activity showed significantly lower values for males infected withLigula intestinalisfrom MS (25%) and for infected females from LTS (55%).L. intestinalis-infected female chub (Leuciscus cephalus) from LTS also appeared to have a lower GST-activity. Thus, it could be shown that the presence of parasites significantly affects GST-activity in different fish species resulting in a decreased GST-activity due to infection. Our results therefore emphasize the need for more integrative approaches in environmental pollution research to clearly identify the possible effects of parasites in an effort to develop biomarkers for evaluating environmental health.

Analytical methods for determining metabolites of polycyclic aromatic hydrocarbon (PAH) pollutants in fish bile: A review

The determination of polycyclic aromatic hydrocarbon (PAH) metabolites in bile can serve as a tool for assessing environmental PAH exposure in fish. Biliary PAH metabolite levels can be measured using several analytical methods, including simple fluorescence assays (fixed fluorescence detection or synchronous fluorescence spectrometry); high-performance liquid chromatography with fluorescence detection (HPLC-F); gas chromatography-mass spectrometry (GC-MS) after deconjugation, extraction and derivatization of the bile sample, and finally by advanced liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) methods. The method alternatives are highly different both with regard to their analytical performance towards different PAH metabolite structures as well as in general technical demands and their suitability for different monitoring strategies. In the present review, the state-of-the-art for these different analytical methods is presented and the advantages and limitations of each approach as well as aspects related to analytical quality control and inter-laboratory comparability of data and availability of certified reference materials are discussed.

Activity of Phase I and Phase II enzymes of the benzo[a]pyrene transformation pathway in zebrafish (Danio rerio) following waterborne exposure to arsenite

The environmental pollutants inorganic arsenic (iAs) and benzo[a]pyrene (B[a]P) are carcinogens often found together in groundwater. The hepatic metabolism of B[a]P is a multi-step process requiring several Phase I and Phase II enzymes, notably cytochrome p450 1A (CYP1A), epoxide hydrolase (EH), and glutathione S-transferase (GST). The purpose of this study was to examine the effect of arsenite (As(III)) on the activity of these enzymes in vivo utilizing adult zebrafish (Danio rerio). Zebrafish were exposed to either 0.4 microM B[a]P, 0.4 microM B[a]P+0.4 microM As(III), 0.4 microM B[a]P+8 microM As(III), 0.4 microM As(III), or 8 microM As(III) for 7 days. Co-exposures to As(III) and B[a]P led to significant decreases in CYP1A enzyme activity (approximately 3-fold) when compared to exposure to B[a]P alone. No similar effects occurred with EH or GST, although B[a]P exposure did significantly increase EH activity. Furthermore As(III) and B[a]P co-exposures significantly decreased CYP1A transcript levels (up to 35-fold) when compared to B[a]P. However, B[a]P-induced CYP1A protein levels remained elevated following co-exposures to As(III). This evidence suggests that As(III) has the potential to modify components of the B[a]P biotransformation pathway in vivo via a disruption of CYP1A activity by way of both pre- and post-translational mechanisms.

Assessment of contamination of the Svitava and Svratka rivers in the Czech Republic using selected biochemical markers

The aim of the present study is to assess aquatic ecosystem contamination using selected biochemical markers: cytochrome P450, ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), tripeptide glutathione, vitellogenin, and 11-ketotestosterone in chub (Leuciscus cephalus L.). Seven locations on the Svitava and Svratka rivers (in the Brno conurbation, Czech Republic) were assessed. The results were compared with the levels of the most important inductors of these biomarkers: organic pollutants hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), DDT and its metabolites, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons in bottom sediment, fish muscle, and semipermeable membrane devices (SPMDs) and metals in sediment. The highest levels of pollutants were observed at sites situated downstream from Brno, especially at Modrice and Rajhradice. Significant positive correlations (p < 0.05) were found between EROD activity and HCH concentration in SPMDs, and also between GST and EROD activity with HCB concentration in muscle, after adjusting for age.

Seasonal variation of the metal (Zn, Fe, Mn) and metallothionein concentrations in the liver cytosol of the European chub (Squalius cephalus L.)

Seasonal variations of biometric parameters as well as metal and protein concentrations were analyzed in the liver cytosol of indigenous European chub (Squalius cephalus L.). Fish sampling was carried out in the reproductive (spring) and non-reproductive period (autumn) in order to define parameters which are seasonally dependent. The specimens caught in the spring period had higher biometric (liver mass, condition and hepatosomatic indices) and some biochemical parameters (metallothionein (MT) and Mn) that are characteristic for the reproductive period. Contrary, Fe hepatic cytosolic concentrations were significantly lower in specimens from spring than in autumn period. Total cytosolic proteins, Cu and Cd concentrations were not seasonally dependent. Range of constitutive levels was determined for total cytosolic proteins (17.7 to 24.7 mg ml(-1)) from the whole set of data. Constitutive range of seasonally dependent parameters MT (207 to 337 microg ml(-1)) and Mn (0.11 to 0.19 microg ml(-1)) is based on the data from non-reproductive period. In order to avoid the interference of reproductive cycle on the level of selected biochemical parameters, it is recommended to perform chub sampling during non-reproductive period.

Combined use of bioindicators and passive samplers for the assessment of river water contamination with metals

In autumn 2005, the site-specific variability of cytosolic metal and protein concentrations in gills of European chub from the Sava River could be mostly associated with gill mass variability. In spring 2006, the correlations of metals and proteins with gill mass were mainly nonsignificant, and their site-specific variability could be presumably associated with river water pollution. The spring cytosolic concentrations of Zn, Cu, and Mn did not differ significantly between the sites (medians: 8.37-11.34 microg ml(-1), 68.2-86.2 ng ml(-1), and 55.9-68.6 ng ml(-1), respectively). Increased cytosolic Cd concentrations were obtained at Oborovo and Lukavec Posavski (median: 4.01 ng ml(-1))-the sites influenced by pollution sources from two major urban areas-compared with the remaining sampling sites (median: 1.93 ng ml(-1)). Cytosolic Fe concentrations were almost two times higher at Jasenovac (median: 11.98 microg ml(-1)) compared with the concentrations at Sava-Zagreb (median: 6.72 microg ml(-1)). Labile Fe concentrations measured in river water with passive samplers indicated that cytosolic Fe concentrations in the spring possibly reflected water-borne Fe uptake. The spring cytosolic protein concentrations decreased from upstream (Otok Samoborski: 27.2 +/- 5.6 mg ml(-1)) toward the downstream sites (Lukavec Posavski: 14.8 +/- 2.8 mg ml(-1)), possibly because of the influence of organic pollution and water toxicity. The spring period seems to be a more appropriate season for the assessment of the river water pollution if chub gills are used as the target organ.

The assessment of natural causes of metallothionein variability in the gills of European chub (Squaliuscephalus L.)

The possible causes of the variability of gill metallothionein (MT) levels were studied on 182 specimens of 2- and 3-year old European chub (Squaliuscephalus L.) from the Sava River in Croatia. The most pronounced differences in MT levels were obtained between three sampling campaigns, and especially between periods with presumably different metabolic activities (April/May 2006 vs. September 2005 and 2006). Next to the probable influence of metabolic activity on MT level, the correlation analysis indicated a significant association between MTs and the fish size. Differences between males and females, as well as between mature and non-mature fish, were not observed in the young group of studied chub even in the spring reproductive season. Based on the analysis of the site-specific MT variability, it could be concluded that, under the conditions of low dissolved metal concentrations in the river water (as reported for the Sava River), MTs seem to be more affected by different biotic factors than by metal exposure. Therefore, MTs measured in this study were considered as the constitutive gill MT levels of young European chub. The constitutive MT ranges were defined separately for the season of lower metabolic rate (autumn: 1.31-2.00 mg g(-1)) and the season of higher metabolic activity (spring: 2.15-2.95 mg g(-1)).

Protein and metal concentrations in two fractions of hepatic cytosol of the European chub (Squalius cephalus L.)

Indigenous specimens of European chub were caught at five sites in Sava River during two successive non-reproductive periods and used as bioindicator organisms for the assessment of metal accumulation. Liver was selected as a target organ and the metal concentrations (Zn, Cu, Fe, Mn, and Cd) were determined in two fractions of hepatic cytosol, namely in untreated (S50) and heat-treated (HT S50) fraction. In addition, the concentrations of total cytosolic proteins were measured in untreated (S50) fractions, whereas the concentrations of specific metal-binding proteins, i.e. metallothioneins, were determined in the heat-treated fractions. Concentrations of Zn and Fe were significantly higher in the untreated compared to heat-treated cytosol, because these metals are associated to the heat-sensitive metalloenzyme and high molecular mass proteins. On the contrary, Cu, Mn and Cd were predominantly present in the heat-treated cytosol, which contains metallothioneins. In both fractions of hepatic cytosol, nonessential metal Cd showed statistically significant increase from the upstream sites (median 5 ng mL(-1)) toward the downstream site Jasenovac (median 11 ng mL(-1)). The metallothionein concentrations, on the contrary, did not differ between sites, probably due to low dissolved and labile concentrations of metals known as metallothionein inducers (Zn, Cu, and especially Cd) in river water. Therefore, Cd concentrations in hepatic cytosol of European chub can be recommended as an early-warning marker of fish chronic exposure to Cd from combined sources, water and ingested food.

Effects of pollution on chub in the River Elbe, Czech Republic

The Elbe River is one of the most polluted aquatic ecosystems in the Czech Republic. The effect of three major chemical plants located on the Elbe River (at Pardubice, Neratovice, and Usti nad Labem) on fish was studied in 2004. Health status, chemical concentrations (Hg, PCB, DDT, HCH, HCB, OCS, 4-tert-nonylphenols, 4-tert-octylphenol) in muscle, and biomarkers (hepatic ethoxyresorufin-O-deethylase (EROD), plasma vitellogenin, and plasma 11-ketotestosterone) were assessed in male chub (Leuciscus cephalus L.). Differences between localities upstream (US) and downstream (DS) from the monitored source of pollution were identified. Fish from DS sampling sites showed significantly higher levels of contaminants than fish from US sampling sites. Generally, the concentrations of pollutants in fish from the Elbe sites were significantly higher compared to the reference site. Reduced gonad size, decreased plasma levels of 11-ketotestosterone, EROD and vitellogenin induction, and histopathologies of male gonads indicated harmful effects of aquatic pollution in fish from the Czech portion of the Elbe River.

Chronic toxicity of the Sava River (SE Europe) sediments and river water to the algae Pseudokirchneriella subcapitata

The Sava River, the largest and most commercially valuable water body in the riparian countries, receives inputs of organic and inorganic compounds from a variety of domestic and industrial activities that may affect the health of human beings and wildlife. In this work, the chronic toxicity of sediment, sediment porewater and surface water from the Sava River and connecting tributaries to the freshwater algae Pseudokirchneriella subcapitata was assessed to characterise the potential impact on aquatic organisms. Samples of different environmental matrices were either tested directly (porewater) or subjected to pre-concentration (sediments and surface water) prior to testing in a 72 h growth inhibition assay using P. subcapitata. The results show that a combination of pre-concentration and bioassay testing was able to characterise the toxic potential and to identify several compartment-specific "hot spots" along the Sava River. Based on the resulting data, a crude risk assessment identified that some of the locations may represent a risk to algae. Additional testing using multiple species and exposure phases is required to conduct a thorough risk assessment, however.