Iedt

SJa

b

ARRA

KABDGMO

1

ocailc2tat

R1

1h

Ecological Indicators 32 (2013) 212– 221

Contents lists available at SciVerse ScienceDirect

Ecological Indicators

jou rn al hom epage: www.elsev ier .com/ locate /eco l ind

nfluence of some metal concentrations on the activity of antioxidantnzymes and concentrations of vitamin E and SH-groups in theigestive gland and gills of the freshwater bivalve Unio tumidus fromhe Serbian part of Sava River

lavica Borkovic-Mitic a,∗, Sladan Pavlovic a, Branka Perendijaa, Svetlana Despotovic a,elena Gavric a, Zoran Gacic b, Zorica Saicic a

Department of Physiology, Institute for Biological Research “Sinisa Stankovic”, University of Belgrade, Belgrade, SerbiaInstitute for Multidisciplinary Research, University of Belgrade, 11000 Belgrade, Serbia

a r t i c l e i n f o

rticle history:eceived 26 July 2012eceived in revised form 15 March 2013ccepted 20 March 2013

eywords:ntioxidant enzymesiomarkersigestive glandills

a b s t r a c t

We examined whether the freshwater bivalve Unio tumidus from the Sava River can serve as a bioindica-tor organism for long-term biomonitoring of river ecosystems for the presence of metal pollutants. To thisend, we assessed in the digestive glands and gills of mussels, changes in activity of antioxidant enzymes:superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase(GR), the phase II biotransformation enzyme glutathione-S-transferase (GST)), and changes in the con-centrations of the non-enzymatic components of the antioxidant system (vitamin E and sulfhydryl groups(-SH), after exposure to metals in the environment. Mussels were collected at four sites where the con-centrations of dissolved metals (Cu, Cd, Zn, Fe, Mn, Hg, Ni, As, Pb) were quantified. Cu, Ni and As exertedconcentration-dependent inhibitory effects on CAT and GST activities. Increasing concentrations of Cd

etalsxidative stress

promoted increases in GSH-Px activity and -SH concentration. In response to increased Zn concentrationGR activity increased whereas Fe promoted decreased enzymatic activity. Negative correlations betweenthe concentrations of Cu and Cd and vitamin E, and a positive correlation between Mn and vitamin Econcentrations were detected. The described correlations between components of the antioxidant sys-tem and metal levels in the environment reveal a high physiological sensitivity of freshwater mussels topollution, supporting their use in biomonitoring of metal contamination in river ecosystems.

. Introduction

Risk assessment of environmental pollution cannot be basednly on chemical analysis since this cannot provide a clear indi-ation of the toxic effects of pollutants on an aquatic environmentnd living organisms (Livingstone, 2001). Among many other tox-cants, environmental poisoning by metals has increased in theast decades due to the extensive use of metals in agricultural,hemical and industrial processes (Cheung et al., 2003; Jing et al.,006). Exposure of aquatic organisms to metals can increase reac-

ive oxygen species (ROS) generation, leading to oxidative stress,s has been reported in many aquatic organisms after exposureo sublethal concentrations of some metals, such as Cu, Cd, Pb

∗ Corresponding author at: University of Belgrade, Institute for Biologicalesearch “Sinisa Stankovic”, Department of Physiology, Bulevar despota Stefana 142,1060 Belgrade, Serbia. Tel.: +381 11 2078 341; fax: +381 11 2761 433.

E-mail address: borkos@ibiss.bg.ac.rs (S. Borkovic-Mitic).

470-160X/$ – see front matter © 2013 Elsevier Ltd. All rights reserved.ttp://dx.doi.org/10.1016/j.ecolind.2013.03.024

© 2013 Elsevier Ltd. All rights reserved.

and Fe (Almeida et al., 2004; Fernández et al., 2010). On the otherhand, some metals such as iron, copper, zinc and manganese areessential metals. They play important roles in biological systems,whereas metals such as mercury, lead and cadmium are non-essential metals and are toxic, even in trace amounts. However, theessential metals can also produce toxic effects when their intake isexcessively elevated (Türkmen and Ciminli, 2007). The most impor-tant trace and toxic elements from the point of view of waterpollution are Al, As, Cd, Cr, Cu, Hg, Ni, Pb and Zn. Metals, such as Cd,Ni, Cr, Pb and Hg, are toxic to aquatic organisms mainly because oftheir oxidative potential (Vlahogianni et al., 2007).

All oxygen-utilizing organisms possess a constitutive antioxi-dant system that consists of both enzymatic and non-enzymaticcomponents that reduce and render harmless potentially toxicoxidative substances such as the reactive oxygen species (ROS) that

are continuously produced as by-products of aerobic metabolism(Halliwell and Gutteridge, 1999). In aerobic organisms, antioxidantdefences are comprised of protective enzymes and non-enzymaticscavengers that prevent the uncontrolled formation of free

gical I

rc1(I2wopaiagimtmstalo

blrae

baoca

eH(Gvttgtatr

2

2

etMa(tefiHufci

S. Borkovic-Mitic et al. / Ecolo

adicals and activated oxygen species (Doyen et al., 2006). Theentral antioxidant enzymes are superoxide dismutase (SOD, EC.15.1.1), catalase (CAT, EC 1.11.1.6) and glutathione peroxidaseGSH-Px, EC 1.11.1.9) (Halliwell and Gutteridge, 1999). The phaseI biotransformation enzyme glutathione-S-transferase (GST, EC.5.1.18) catalyses the conjugation of reduced glutathione (GSH)ith various electrophilic substances and plays a role in preventing

xidative damage by conjugating the breakdown products of lipideroxides to GSH (Van der Oost et al., 2003). Some non-enzymaticntioxidant compounds such as vitamin E are known to play anmportant role by acting as biological antioxidants, protecting cellsnd tissues from the damaging effects of free radicals and sin-le oxygen (Barim and Karatepe, 2010). Sulfhydryl groups play anmportant role in biochemical processes. Protein SH-groups bind

etals, and the intracellular fates of both essential and nonessen-ial metal ions strongly depend on the level of thiol-containing

olecules (Eaton et al., 1980). Labieniec and Gabryelak (2007)howed that the SH group content is a marker of protein oxida-ion and that the oxidative modification of proteins increased in

concentration-dependent manner. The observed decrease in theevels of SH-groups in cells exposed to pollutants reveals their pro-xidant effects on proteins.

Freshwater mussels such as Unio tumidus are well suited foriomonitoring because they are reasonably sized, largely sessile,

ong-lived, widely distributed, available in large quantities andelatively tolerant to xenobiotics. Because mussels are known toccumulate various pollutants, they are used to assess the earlyffects of pollution in water ecosystems (Vidal-Linán et al., 2010)

The Sava River is an important waterway. In addition to heavyoat traffic, the river is under the influence of hydro-morphologicallterations, industrial “hot-spots”, and agriculture. The Serbian partf the Sava has been influenced by communal wastewater and dis-harges from metallurgical, chemical, leather, textile, food and pulpnd paper industries (Paunovic et al., 2008).

The purpose of this study was to examine the influence ofxtended exposure to dissolved trace metals Cu, Cd, Zn, Fe, Mn,g, Ni, As and Pb on the activity of antioxidant defence enzymes

SOD, CAT, GSH-Px, GR and the phase II biotransformation enzymeST), and on the concentrations of the non-enzymatic components,itamin E and SH-groups in the freshwater bivalve U. tumidus inhe aquatic environment. For this reason, we used gills and diges-ive gland as the main sites of xenobiotic uptake and oxyradicaleneration. Field studies were performed on the Serbian part ofhe Sava River at four sites, Jamena, Sremska Mitrovica, Sabacnd Ostruznica, that are characterized by different environmen-al conditions and which are therefore expected to elicit differentesponses in the bivalve.

. Materials and methods

.1. Site description and sample collection

Specimens of the freshwater mussel U. tumidus (n = 40; 10 fromach locality) were collected in August 2006 at four localities alonghe Sava River: Jamena (44◦52′41.6′′N and 19◦05′21.0′′E), Sremska

itrovica (44◦57′55.4′′N and 19◦36′01.4′′E), Sabac (44◦46′17.2′′Nnd 19◦42′16.1′′E) and Ostruznica (44◦43′19.5′′N and 20◦18′15.5′′E)Fig. 1). The sampling sites were selected based on the location ofhe stations used for routine monitoring performed by the Hydrom-teorological Service of the Republic Serbia (RHMZ, 2006). Therst site is located on the border with the Republic of Bosnia anderzegovina; the second and the third localities are located in an

rbanized region with considerable anthropogenic influence; theourth site is in an agricultural zone. Freshwater mussels wereollected by diving. Water samples are collected for routine mon-toring twice a month throughout the year from a sampling depth

ndicators 32 (2013) 212– 221 213

of 0.5 m. Each water sample was collected at three points: the leftbank, the right bank and midstream, in order to determine the meanand standard error. Some of the analyses were performed in situ(water temperature, pH, dissolved oxygen) using mobile analyticalequipment. Alkalinity was analyzed by titration with an automaticburette, immediately after the samples were taken, on the boat, inthe field laboratory. In order to analyze other quality parameters,the samples were fixed according to the standard procedure andstored for further laboratory analysis. The specimens of U. tumiduswere selected by shell size (6–7 cm) and after collecting, all speci-mens were kept on ice. Water quality assessment was performedaccording to the regulations of the Republic of Serbia, as recom-mended by the International Commission for the Protection of theDanube River (ICPDR, 2006) and Water Framework Directive (WFD,2000).

2.2. Tissue processing

The digestive gland and the gills were dissected on site immedi-ately after collection, dried, weighed and frozen in liquid nitrogen(−196 ◦C) until biochemical determination. The tissues of eachmussel were analyzed separately; they were not pooled for thebiochemical assays. All of the samples were stored under the sameconditions in order to avoid differences related to storage condi-tions. The tissues were kept at 80 ◦C until analysis. The tissues wereminced and homogenized in 5 volumes of 25 mmol/L sucrose con-taining 10 mmol/l Tris–HCl, pH 7.5 at 4 ◦C (Lionetto et al., 2003) withan IKA-Werk Ultra-Turrax homogenizer (Janke and Kunkel, Staufen,Germany) (Rossi et al., 1983). The homogenates were sonicated for30 s at 10 kHz on ice to release enzymes (Takada et al., 1982), fol-lowed by centrifugation in a Beckman ultracentrifuge at 85,000 × gfor 90 min at 4 ◦C. The resulting supernatants were used for furtherbiochemical analyses.

2.3. Biochemical analyses

Protein concentration in the supernatants was determinedaccording to the method of Lowry et al. (1951) using bovineserum albumin as a standard and expressed in mg/g wet mass.The activities of the antioxidant enzymes were measured simul-taneously in triplicate for each sample using a Shimadzu UV-160spectrophotometer with a temperature-controlled cuvette holder.The activity of SOD was assayed by the epinephrine method (Misraand Fridovich, 1972). One unit of SOD activity was defined as theamount of protein causing 50% inhibition of the autoxidation ofadrenaline at 26 ◦C, and was expressed as specific activity (U/mgprotein). CAT activity was evaluated by the rate of hydrogen per-oxide (H2O2) decomposition (Claiborne, 1984) and one unit of CATactivity expressed as �mol H2O2/min/mg protein. The activity ofGSH-Px was determined following the oxidation of nicotinamideadenine dinucleotide phosphate (NADPH) as a substrate with t-butyl hydroperoxide (Tamura et al., 1982) and one unit of GSH-Pxactivity expressed in nmol NADPH/min/mg protein. The activity ofGR was measured using the method of Glatzle et al. (1974). Thismethod is based on the capability of GR to catalyze the reductionof oxidized glutathione (GSSG) to reduced glutathione (GSH), usingNADPH as a substrate in a phosphate buffer (pH 7.4). One unit ofGR activity was expressed as nmol NADPH/min/mg protein. Theactivity of GST towards 1-chloro-2,4-dinitrobenzene (CDNB) wasdetermined by the method of Habig et al. (1974), and one unit ofGST activity expressed as nmol GSH/min/mg protein The methodis based on the reaction of CDNB with the SH group of GSH, which

is catalyzed by GST contained in the samples.

The concentration of vitamin E was measured by the methodof Desai (1984), which is based on the reduction of Fe3+ to Fe2+

in the presence of tocopherol, and the production of a coloured

214 S. Borkovic-Mitic et al. / Ecological Indicators 32 (2013) 212– 221

a Riv

cEg(�

U

2

semWti

Fig. 1. Location map of sampling sites on the Serbian part of the Sav

omplex with bathophenanthroline. The concentration of vitamin is expressed as �g/g wet mass. The concentration of sulfhydrylroups was determined using 5,5′-dithio-bis-(2-nitrobenzoic acid)DTNB) according to the Ellman (1959) method, and expressed inmol/g wet mass.

All chemicals were obtained from Sigma–Aldrich (St Louis, MO,SA).

.4. Trace metal concentrations in water of Sava River

The concentrations of dissolved metals in the water were mea-ured during period of one year before sampling of organisms. Wexamined the effects of extended exposure to the dissolved trace

etals, Cu, Cd, Zn, Fe, Mn, Hg, Ni, As and Pb on freshwater bivalves.ater samples are collected for routine monitoring twice a month

hroughout the year. Water samples are collected for routine mon-toring twice a month throughout the year (at the beginning and

er: (1) Jamena, (2) Sremska Mitrovica, (3) Sabac and (4) Ostruznica.

middle of each month). The water were pre-filtered in the fieldand stabilized with nitric acid. The analysis of trace metals wasperformed by Atomic Absorption Spectrometry (AAS, Varian Spec-trAA 640 Graphite Furnace, with Zeeman background correctionand Varian SpectrAA 200 Flame AAS).

2.5. Statistical analyses

Differences between the activities of antioxidant enzymes andconcentrations of non-enzymatic components from four differentlocalities were determined using the non-parametric Mann-Whitney U-test. The null hypthesis is rejected if p < 0.05. Spearman

rank order correlation was performed between the activities ofantioxidant enzymes and the concentrations of non-enzymaticcomponents (vitamin E, SH-groups) with the concentrations of dis-solved metals. Statistical analyses were performed with STATISTICA

gical I

6a

3

3

wwJt(

rmtutamcinw

3c

rtcdta(agid(nsdfhvdgi

3ac

UwstiSdls

S. Borkovic-Mitic et al. / Ecolo

.0. The analytical protocols described by Darlington et al. (1973)nd Dinneen and Blakesley (1973) were followed.

. Results

.1. The physicochemical parameters of water

The some physicochemical parameters are shown in Table 1 andere measured at the time of sampling. The water temperatureas nearly the same at all sites, varying from 22.03 ± 0.09 ◦C in

amena to 24.07 ± 0.03 ◦C in Ostruznica. The slight increase of wateremperature is probably due to thermal power plant in Obrenovacnear Ostruznica).

Oxygen saturation was the lowest at locality Jamena (66%). Theeason for this phenomenon probably lies in the fact that a deep,uddy lowland river such as the Sava, contains more organic mat-

er; it has a lower dissolved oxygen concentration because bacteriase the oxygen to break down organic matter. The oxygen concen-ration in the water will vary depending on the physical, chemicalnd biochemical activities in the river. Under standard conditionsost lowland rivers exhibit at least 60% saturation (60–120). The

oncentrations of dissolved oxygen, pH and alkalinity were sim-lar at all four sites. The concentrations of ammonium, nitrites,itrates, total nitrogen, organophosphates and total phosphorusere approximately similar but highest at the Jamena site.

.2. Antioxidant enzyme activities and vitamin E and SH-grouponcentrations in different tissues

The activities of superoxide dismutase (SOD) and glutathioneeductase (GR) were higher in the gills (Fig. 3A and D) than inhe digestive gland (Fig. 2A and D). These differences were statisti-ally significant (p < 0.05), except at the site Jamena for superoxideismutase (SOD) and glutathione reductase (GR) activities, and athe location of Sremska Mitrovica for glutathione reductase (GR)ctivity (Table 4). The opposite results were observed for catalaseCAT) and glutathione-S-transferase (GST) activities. Catalase (CAT)ctivity was markedly higher in the digestive gland than in theills (Fig. 2B and Fig. 3B). Glutathione peroxidase (GSH-Px) activ-ty was nearly the same in both tissues and statistically significantifferences between the tissues were only at the site OstruznicaTable 4, Fig. 2C). Glutathione-S-transferase (GST) activity was sig-ificantly higher in the digestive gland compared to the gills at allites (p < 0.05) (Table 4, Figs. 2E and 3E). Figs. 2F and 3F show thatigestive gland and gills contain equal amounts of vitamin E, exceptor the case of Sremska Mitrovica, where vitamin E concentration isigher in digestive gland than in gills. On this site (Sremska Mitro-ica) we have only statistically significant difference between theigestive gland and gills (p < 0.05). The concentration of sulfhydrylroups was significantly higher (p < 0.05) in the digestive gland thann the gills at all four sites (Table 4, Figs. 2G and 3G).

.3. Comparison of the influence of different localities onntioxidant enzyme activities and vitamin E and SH-grouponcentrations

Superoxide dismutase (SOD) activity in the digestive gland of. tumidus was highest in the mussels collected at the Jamena site,hile gill superoxidedismutase (SOD) activity was highest in the

pecimens from the Sremska Mitrovica locality (Figs. 2A and 3A). Inhe digestive gland of U. tumidus superoxidedismutase (SOD) activ-ty was statistically significant when compared sites Jamena with

ˇabac and Ostruznica (p < 0.05). The activity of catalase (CAT) in theigestive gland and gills was highest in specimens from the Sabac

ocality (Figs. 2B and 3B), and was significantly different from otherites (p < 0.05). The activity of glutathione peroxidase (GSH-Px) in

ndicators 32 (2013) 212– 221 215

the digestive gland and gills was the highest in specimens caughtat Ostruznica (Figs. 2C and 3C), with differences that are statisti-cally significant when compared with Jamena, Sremska Mitrovicaand Sabac (p < 0.05). The activity of digestive gland glutathionereductase (GR) was highest in mussels collected at the SremskaMitrovica site, while gill GR activity was highest in specimens fromthe Sabac site (Figs. 2D and 3D). The sites are significantly differentwhen we compared glutathione reductase (GR) activity in the gills(p < 0.05). The highest glutathione-S-transferase (GST) activity inthe digestive gland was measured in specimens from the Strem-ska Mitrovica, with statistically significant differences betweensites only in digestive gland (p < 0.05). In contrast, glutathione-S-transferase (GST) activities in gills did not differ among the sites(Figs. 2E and 3E). The vitamin E concentration in the digestive glandand gills was greatest in the mussels from the Sabac site (Figs. 2F and3F), with statistically significant differences between sites in bothtissues (p < 0.05). The concentrations of SH-groups in the digestiveglands and gills were highest in specimens from Ostruznica (Figs.2G and 3G), with statistically significant differences between sites(p < 0.05).

3.4. Concentrations of dissolved metals at different localities

Table 2 shows the concentration of dissolved metals (maximumallowed concentration, mean, minimum, maximum and standarderror) in the water of the Sava River for the whole year beforesampling mussels. The concentrations of dissolved metals accord-ing to TNMN standards (ICPDR, 2006) exhibited seasonal variationsat different sites. The maximum concentration of Cu amounted to21 �g/l (July 2006) at the Jamena site, and 29 �g/l (August 2006) atSremska Mitrovica. These values exceeded the maximum allowedconcentration (2 �g/l) of Cu in water. The concentration of Cd at allfour sites was above the maximum permitted limit of 0.1 �g/l. Theconcentration of dissolved Zn exceeded the maximum allowableconcentration of 5 �g/l (Table 2). The concentration of dissolved Fewas not elevated throughout the examined period of one year. Theconcentration of Hg at all four sites was above the maximum per-mitted concentration of 0.1 �g/l. The concentration of dissolved Niwas increased at all four sites and exceeded the maximum per-missible concentration of 1 �g/l. The concentration of dissolvedAs was increased in the specified period and exceeded the max-imum allowed concentration of 1 �g/l (Table 2). The concentrationof dissolved Pb was exceeded the maximum allowed concentrationof 1 �g/l, particularly in the Ostruznica site where the maximumconcentration of Pb was 5 �g/l (August 2006).

3.5. Correlations between antioxidant enzyme activities, vitaminE, SH-group concentrations of the freshwater mussel Uniotumidus and concentrations of dissolved metals in the Sava River

Results from the Spearman Rank Order Correlations are pre-sented in Table 3. Significant negative correlations were foundbetween CAT activity and the concentrations of Cu, Ni and As, whichmeans that an increase of the concentration of these metals led toa decrease in CAT activity. A positive correlation was establishedbetween the activity of GSH-Px and the concentration of Cd. Asignificant positive correlation was observed between GR activityand Zn concentration, and a negative correlation with Fe. Negativecorrelations were observed between GST activity and the concen-trations of Cu, Ni and As, and a positive correlation between GST

activity and the concentration of Fe. The concentration of vita-min E displayed negative correlations with the concentrations ofCu and Cd, and a positive correlation with Mn. The concentrationof sulfhydryl groups displayed a positive correlation with Cd. All

216 S. Borkovic-Mitic et al. / Ecological Indicators 32 (2013) 212– 221

Fig. 2. Digestive gland of the freshwater bivalve Unio tumidus: activity of antioxidant enzymes and concentrations of vitamin E and SH-groups determined in populationsfrom the sampling localities Jamena, Sremska Mitrovica, Sabac, and Ostruznica. The data are expressed as mean ± S.E. The non-parametric Mann-Whitney U-test wasused to establish significant differences between samples. A minimum significance level of p < 0.05 was accepted (significantly different values are marked with lettersindicating which values are different from each other: a, b and c indicate differences among enzyme activities at the sampling localities: letter “a” is for site Jamena, “b”for site Sremska Mitrovica and “c” for Sabac). Abbreviations: SOD-superoxide dismutase, CAT-catalase, GSH-Px-Glutathione peroxidase, GR-Glutathione reductase, GSTglutathione-S-transferase, SH-sulfhydryl groups.

S. Borkovic-Mitic et al. / Ecological Indicators 32 (2013) 212– 221 217

Fig. 3. Gills of the freshwater bivalve Unio tumidus: activity of antioxidant enzymes and concentrations of vitamin E and SH-groups determined for populations at the samplinglocalities Jamena, Sremska Mitrovica, Sabac, and Ostruznica. The data are expressed as mean ± S.E. The non-parametric Mann-Whitney U-test was used to establish significantdifferences between samples. A minimum significance level of p < 0.05 was accepted (significantly different values are marked with letters indicating which values are differentfrom each other: a, b and c indicate differences among enzyme activities at the sampling localities: letter “a” is for site Jamena, “b” for site Sremska Mitrovica and “c” forSabac). Abbreviations: SOD-superoxide dismutase, CAT-catalase, GSH-Px-Glutathione peroxidase, GR-Glutathione reductase, GST glutathione-S-transferase, SH-sulfhydrylgroups.

218 S. Borkovic-Mitic et al. / Ecological Indicators 32 (2013) 212– 221

Table 1Mean and standard error of some physico-chemical parameters at the sampling localities Jamena, Sremska Mitrovica, Sabac and Ostruznica of Sava River in August 2006.Each water sample is taken at three points: the left, the right bank and midstream, in order to determine the mean and standard error. Part of the analysis was done in situ(water and air temperature, pH, dissolved oxygen) by using the mobile analytical equipment.

Jamena Sremska Mitrovica Sabac Ostruznica

Water temperature (◦C) 22.03 ± 0.09 22.40 ± 0.06 22.93 ± 0.07 24.07 ± 0.03Air temperature (◦C) 18.97 ± 0.12 28.10 ± 0.70 26.10 ± 0.24 28.40 ± 0.15O2 (mg/L) 6.33 ± 0.09 6.70 ± 0.56 6.43 ± 0.03 6.23 ± 0.15O2 (%) 66 82.5 75.9 73.9pH 7.83 ± 0.03 7.77 ± 0.07 7.77 ± 0.03 7.57 ± 0.03Alkalinity (mmol/L) 3.30 ± 0.50 3.63 ± 0.15 3.7 ± 0.03 3.63 ± 0.03Ammonium-N (mg/L) 0.12 ± 0.02 0.05 ± 0.03 0.04 ± 0.01 0.05 ± 0.01Nitrite-N (mg/L) 0.008 ± 0.002 0.005 ± 0.001 0.0020 ± 0.0003 0.006 ± 0.001Nitrate-N (mg/L) 0.80 ± 0.33 0.40 ± 0.09 0.60 ± 0.07 0.70 ± 0.09Total nitrogen (mg/L) 1.60 ± 0.15 1.30 ± 0.06 1.40 ± 0.06 1.30 ± 0.09Orthophosphate-P (mg/L) 0.07 ± 0.005 0.05 ± 0.001 0.05 ± 0.001 0.05 ± 0.0003Total phosphorous (mg/L) 0.10 ± 0.001 0.07 ± 0.001 0.06 ± 0.001 0.06 ± 0.002

Table 2The concentration of dissolved metals in the water of the Sava River. The parameters were measured in the period of one year before sampling the mussels. Water samplesare collected for routine monitoring twice a month throughout the year (at the beginning and middle of each month).. Displayed are maximum allowed concentration, themean values, minimum, maximum and standard error.

Locality MAC Jamena Sremska Mitrovica Sabac Ostruznica

Mean Min. Max. S. E. Mean Min. Max. S. E. Mean Min. Max. S. E. Mean Min. Max. S. E.

Cooper (Cu) 2.00 5.82 1.00 21.00 1.71 6.33 1.00 29.00 2.47 4.20 1.00 18.00 1.20 7.50 1.00 19.00 1.33Cadmium (Cd) 0.10 0.20 0.20 0.20 - 0.23 0.20 0.40 0.02 0.20 0.20 0.20 - 0.23 0.20 0.40 0.01Zinc (Zn) 5.00 9.67 2.00 23.00 6.69 9.25 4.00 22.00 4.27 22.00 6.00 69.00 9.64 13.43 1.00 31.00 4.47Iron (Fe) 0.30 * 0.10 0.02 0.20 0.01 0.04 0.02 0.13 0.01 0.06 0.02 0.11 0.01 0.07 0.02 0.20 0.01Mercury (Hg) 0.10 0.18 0.10 0.60 0.03 0.12 0.10 0.30 0.01 0.11 0.10 0.40 0.01 0.13 0.10 0.60 0.02Manganese (Mn) 0.10* 0.06 0.01 0.30 0.01 0.020 0.010 0.060 0.003 0.03 0.01 0.15 0.01 0.020 0.010 0.080 0.004Nickel (Ni) 1.00 1.70 1.00 4.00 0.20 1.30 1.00 2.00 0.13 1.30 1.00 3.00 0.12 1.52 1.00 4.00 0.18Arsenic (As) 1.00 1.30 1.00 3.00 0.15 1.31 1.00 2.00 0.12 1.24 1.00 3.00 0.12 1.55 1.00 4.00 0.19Lead (Pb) 1.00 1.00 1.00 1.00 – 1.00 1.00 1.00 – 1.00 1.00 1.00 – 1.24 1.00 5.00 0.19

All values in �g/l, except for Fe and Mn in mg/l.MAC- maximum allowed concentration acording to TNMN standards (ICPDR, 2006); *Fe (over 0.30 Class III), *Mn (over 0.10 Class III).Atomic Spectroscopy Detection Limits (micrograms/litre): Cooper (Cu) 0.014; Cadmium (Cd) 0.002; Zinc (Zn) 0.02; Iron (Fe) 0.06; Mercury (Hg) 0.6; Manganese (Mn) 0.005;Nickel (Ni) 0.07; Arsenic (As) 0.05 and Lead (Pb) 0.05.

Table 3Statistical dependence between antioxidant enzyme activities, vitamin E, SH-group concentrations of the freshwater mussel Unio tumidus with concentrations of dissolvedmetals in the Sava River. Table values: calculation results of Spearman’s rank correlation coefficient, in brackets: p-values a significant relationship assumed at p < 0.05(marked with *).

Cooper (Cu) Cadmium (Cd) Zinc (Zn) Iron (Fe) Mercury (Hg) Manganese (Mn) Nickel (Ni) Arsenic (As) Lead (Pb)

SOD 0.04 (0.73) −0.03 (0.83) 0.06 (0.78) −0.17 (0.16) −0.003 (0.98) 0.011 (0.93) −0.15 (0.22) −0.03 (0.83) −0.19 (0.10)CAT −0.52 (0.000007*) −0.12 (0.40) −0.06 (0.80) 0.17 (0.17) 0.06 (0.60) 0.02 (0.89) −0.35 (0.003*) −0.38 (0.001*) −0.08 (0.46)GSH-Px 0.003 (0.98) 0.34 (0.015*) −0.18 (0.43) 0.18 (0.13) −0.12 (0.31) 0.11 (0.35) −0.07 (0.58) 0.04 (0.77) 0.18 (0.12)GR 0.23 (0.07) 0.24 (0.12) 0.45 (0.05*) −0.30 (0.014*) −0.10 (0.40) −0.18 (0.16) 0.23 (0.06) 0.18 (0.15) 0.07 (0.58)GST −0.37 (0.002*) 0.03 (0.85) −0.32 (0.15) 0.27 (0.02*) 0.08 (0.51) −0.01 (0.97) −0.26 (0.03*) −0.26 (0.005*) −0.03 (0.82)Vitamin E −0.30 (0.03*) −0.33 (0.04*) 0.36 (0.14) 0.20 (0.12) 0.02 (0.89) 0.35 (0.006*) −0.02 (0.87) −0.22 (0.10) −0.12 (0.33)

) −0

ca

4

oictmMbipii

SH groups −0.16 (0.21) 0.30 (0.03*) −0.13 (0.57) 0.107 (0.40

orrelations mentioned in this section are statistically significantt p < 0.05.

. Discussion

Changes in the environment as well as disturbed homeostasis inrganisms can be detected by molecular and physiological biomon-toring months after exposure to the pollutants. In our study, metaloncentrations were measured throughout the whole year prioro mussel collection in order to examine seasonal fluctuations of

etal concentrations, also the metal cumulative effect in mussels.ussels have the capacity to concentrate pollutants in the shell,

ind metals with thionein, and then inactivate and isolate them

n calcified granules that are distributed in tissues. The immediaterotective response in bivalves to stress (mechanical or chemical)

s valve closure. In the case of water pollution with metals, the tim-ng of valve closure varies with the metal concentration. Generally,

.12 (0.31) 0.06 (0.64) −0.10 (0.42) −0.14 (0.25) 0.19 (0.10)

higher concentrations lead to a more rapid valve closure (Tran et al.,2004). Bivalves can remain closed in water polluted by Cu dur-ing the initial period, but tend to reopen to resume feeding andrespiration (Jing et al., 2006).

In our investigations, we observed differences in antioxidantenzyme activities in the digestive gland and gills. Higher activi-ties were generally observed in the digestive gland, such as Cossuet al. (1997) reported in their work. Although the digestive glandis of special interest as it is involved in most biotransformationprocesses and redox cycling, it exhibited pronounced fluctuationsin activity between samplings, thus rendering the interpretationof results difficult, unlike the data obtained for the gills. Gillsreflects the state of the aquatic environment, and changes in the

antioxidant enzyme activities in gills do not depend on the phys-iological status of molluscs as they do in the digestive gland. Onthe other hand, the antioxidant complex of the digestive gland isaffected not only by the environment but also by certain internal

gical Indicators 32 (2013) 212– 221 219

fMgs

a2r(aaar2oraI2aCdtSt2CiwepveCaeosdfte

bsiaCng(fmcrsPaaectpadT

Table 4Comparision of antioxidant enzymes activity and concentrations of vitamin E andSH-groups in two different tissues (digestive gland and gills) of the freshwaterbivalve Unio tumidus at the sampling localities Jamena, Sremska Mitrovica, Sabacand Ostruznica. The non-parametric Mann-Whitney U-test was used to establishsignificant differences between samples. A minimum significance level of p < 0.05was accepted.

Digestive glandversus gills

Jamena Sremska Mitrovica Sabac Ostruznica

SOD N.S. p < 0.05 p < 0.05 p < 0.05CAT p < 0.05 p < 0.05 p < 0.05 p < 0.05GSH-Px N.S. N.S. N.S. p < 0.05GR N.S. N.S. p < 0.05 p < 0.05GST p < 0.05 p < 0.05 p < 0.05 p < 0.05Vitamin E N.S. p < 0.05 N.S. N.S.

S. Borkovic-Mitic et al. / Ecolo

actors (e.g. nutrition, spawning) (Vidal-Linán et al., 2010).anduzio et al. (2004) suggested that unlike gills, the digestive

land exhibits high fluctuations of enzymatic activities betweeneasons.

Numerous studies have shown that exposure to metals isccompanied by the induction of oxidative stress (Valko et al.,005). Many metals generate oxidative stress either through directeactive oxygen species (ROS) generation or by scavenging thiolsglutathione and cysteine) that act as important non-enzymaticntioxidants (Zhang et al., 2010). On the other hand, enzymaticntioxidants are susceptible to metal exposure via metal inter-ction with sulfhydryl or other functional groups, or via theeplacement of cofactors essential to enzyme function (Xie et al.,009). It is generally accepted that Cu toxicity is the consequencef the generation of ROS by Cu ions via the Fenton or Haber-Weisseactions. It has been suggested that the Cu ion displays a highffinity for protein thiol and amino groups (Letelier et al., 2005).norganic Hg is a highly toxic environmental pollutant (Bando et al.,005). It has been reported that Pb is responsible for ROS gener-tion, including O2

•−, H2O2, and •OH (Bokara et al., 2008). SOD,AT, and GSH-Px play important roles in protection against oxi-ation. However, the excess availability of free radicals can lowerhe levels of antioxidants. Pb exposure has an inhibitory effect onOD; thus it can cause alterations in the mitochondria and facili-ate the release of O2

•− that can inhibit CAT activity (Hansen et al.,007). As expected, increasing Pb concentration lowered SOD andAT activities. A negative correlation between CAT and GST activ-

ties and As concentrations was observed (Table 3). CAT activityas not affected in fish that were exposed to As (Ventura-Lima

t al., 2007), further supporting the efficacy of increased GSH inreventing oxidative perturbations. This contrasts with the obser-ation in that in Clarias batrachus CAT activity increased after Asxposure (Battacharya and Battacharya, 2007). We observed highAT activity in the digestive gland compared to the gills (Figs. 2Bnd 3B). This result is consistent with the finding obtained by Cossut al. (1997) who reported that since gills are more sensitive toxidative stress antioxidant parameters appear inhibited. The highensitivity of gills is the result of their direct exposure to oxygenuring respiration, as well as to a variety of contaminants duringood filtration. High activities of antioxidant defence enzymes inhe digestive gland are related to the bioavailability of pollutantsntering through the digestive tract.

In this study, significant negative correlations were foundetween CAT activity and the concentrations of Cu, Ni and As,uggesting that the activities of antioxidant enzymes decreasedn response to increased ROS generation due to the high bioavail-bility of these metals in the freshwater environment (Table 3).AT inhibition by Cu and Cd has already been reported in the kid-ey of Dicentrarchus labrax (Roméo et al., 2000) and in the brain,ill, liver and kidney of Heteropneustes fossilis after Cd exposureRadhakrishnan, 2009). The distinct antioxidant capacities of dif-erent tissues are linked to the rates of bioaccumulation and the

etabolic and physiological roles of Cu. In Mytilus galloprovin-ialis exposed to 60 �g L−1 Cu for 21 days, different antioxidantesponses were demonstrated in the gill and digestive gland tis-ues (Regoli and Principato, 1995; Maria and Bebianno, 2011).ositive correlations were established between GSH-Px activitynd Cd concentration, GR activity and Zn concentration, and GSTctivity and Fe concentration. Correlations between GSH-relatednzymatic activities (GSH-Px, GR and GST) and Cd, Zn and Fe con-entrations could indicate a coordinated enzymatic regulation ofhese enzymes aimed at restoring the GSH pool that could in turn

ermit an efficient antioxidant response. The significantly lowerctivities of CAT, GSH-Px and GST in gills (p < 0.05) compared to theigestive gland point to a metal-induced oxidative stress in the gills.hese antioxidant responses would therefore seem to constitute

SH groups p < 0.05 p < 0.05 p < 0.05 p < 0.05

N.S.—non significant.

a specific adaptation in the gills to prevent and/or repair metal-induced damage in cellular components (Fernández et al., 2010).Significant negative correlations were detected between GST andCu, Ni and As concentrations (Table 3). Although metals are notnatural substrates for GST, our results suggest that the decreasein GST activity was a reflection of the response to oxidative stressresulting from metal exposure. In their correlation analyses, Vidal-Linán et al. (2010) reported that polycyclic aromatic hydrocarbons,organochlorinated compounds and trace metals affect GST activ-ity in mussels. We observed that the activity of GST was lower inthe gills than in the digestive gland, which could play a protectiverole against oxidative stress. Some researchers suggest that GSTactivity inhibition could occur either through direct action of themetal on the enzyme or indirectly, via the production of ROS thatinteract directly with the enzyme, deplete its substrate GSH, and/orthrough downregulation of GST genes through different mech-anisms (Roling and Baldwin, 2006). Metal accumulation in cellscan lead to decreased availability of GSH due to both binding andoxidation (Canesi et al., 1999). The GST downregulation observedafter exposure to metals such as Cr, Cd, Hg, Zn and As has beenattributed to the inhibition of nuclear transcription factors (NF-�B, AP-1) binding to the gene promoter region, either directly orthrough indirect mechanisms that involve ROS generation (Rolingand Baldwin, 2006).

While many studies have examined the impact of pollution onthe activities of antioxidant enzymes in mussels (Cossu et al., 2000;Borkovic et al., 2005), crayfish (Borkovic et al., 2008) and marinefishes (Pavlovic et al., 2008, Pavlovic et al., 2010), the impact of envi-ronmental factors on the low-molecular components of antioxidantdefences has not been examined extensively. Barim and Karatepe(2010) studied the effects of pollution on the levels of antioxi-dant vitamins A, E, and C, �-carotene and malondialdehyde (MDA)in the hepatopancreas and muscle tissues of freshwater crayfish(Astacus leptodactylus). In their study, vitamin E, C and �-carotenelevels in both hepatopancreatic and muscle tissues were signifi-cantly higher in control samples compared to samples obtainedat the polluted site. There is little information in the literaturedirectly linking the effects of pollution on vitamin E levels in thetissues of aquatic organisms. The differences in vitamin E con-centrations that were observed in the samples obtained from thefour sites on the Sava River may be due to higher levels of heavymetals (Cu, Cd and Mn). Significant negative correlations wereestablished between the concentrations of vitamin E and Cu andCd, and positive correlations between vitamin E and Mn (Table 3).The levels of sulfhydryl groups in freshwater mussels were higher

in the digestive glands than in the gills in the specimens collectedat all four sites. The highest concentrations of sulfhydryl groupswere recorded in the specimens from the Ostruznica site. A signif-icant positive correlation was found between the sulfhydryl group

2 gical I

cooTcaocp

btr(cimteguelpToboCd

5

mtreamwaparamrcsac

A

ans

A

f2

20 S. Borkovic-Mitic et al. / Ecolo

ontent and Cd (Table 3). We measured the highest concentrationf Cd at the Ostruznica site (Table 2), and the highest concentrationf sulfhydryl groups in specimens collected at the same location.his finding mirrors the observation that the concentration of thiolompounds is an effective indicator of Cd water pollution. Kovarovand Svobodova (2009) summarized the effect of Cd on the levelsf thiol compounds in aquatic organisms, observing that the con-entration of thiol compounds is an effective indicator of Cd waterollution, and suggesting its use in biomonitoring applications.

The distribution of contaminants in mussel organs variesecause of differences in the surfaces in contact with contaminants,he differing affinities of pollutants to binding sites and the differentates of accumulation and excretion of pollutants between tissuesYap et al., 2008). In this context, gills represent the first line ofontact with potential contaminants (Almeida et al., 2005). In fact,t has been reported that metals such as Cu, Hg, Cd and Pb accu-

ulate more rapidly in mussels and to a greater extent in the gillshan in tissues such as the mantle, muscle or digestive gland (Canesit al., 1999; Dragun et al., 2004; Marigómez et al., 2002). Digestiveland and mantle tissues accumulate higher levels of polyunsat-rated fatty acids and organic pollutants than the gills (Almeidat al., 2003). Jing et al. (2006) presented the results of Cu accumu-ation in Pinctada fucata, suggest that the digestive gland and gillslay different roles when exposed to different Cu concentrations.he digestive gland was the main organ of Cu accumulation whenysters were exposed to low concentrations of Cu, whereas the gillsecame the target organ in oysters exposed to high concentrationsf Cu. One possible explanation is that the higher concentration ofu affected feeding and thereby the rate of Cu accumulation in theigestive gland (Pipe et al., 1999).

. Conclusions

Presented study is a first report on the effects of metals and enzy-atic and non-enzymatic components responses in the tissues of

he freshwater mussel U. tumidus from the Sava River. The obtainedesults show that the digestive gland and gills responded differ-ntly to the presence of different metals. Correlations between thectivities of antioxidant enzymes, non-enzymatic components andetal concentrations suggest a physiological sensitivity of fresh-ater mussels to metal pollution. These results support the use of

ntioxidant defence enzymes as oxidative stress biomarkers andave the way for further investigations into the defence mech-nisms in the freshwater mussel U. tumidus. From the presentedesults it can be concluded, that investigated antioxidant enzymesnd non-enzymatic components represents suitable biomarkers ofetal pollution and that both digestive gland and gills plays active

ole in oxidative stress generation and antioxidant responses andan therefore be used as bioindicators of metal pollution. At theame time, the investigated metals had the biggest impact on thectivity of the phase II biotransformation enzyme GST that can beonsidered as most suitable biomarker of metal toxicity.

cknowledgments

This study was supported by the Ministry of Education, Sciencend Technological Development of the Republic of Serbia, grantsos. 173041 and 173045. The authors are grateful to Myra Macpher-on Poznanovic for proofreading the manuscript.

ppendix A. Supplementary data

Supplementary data associated with this article can beound, in the online version, at http://dx.doi.org/10.1016/j.ecolind.013.03.024.

ndicators 32 (2013) 212– 221

References

Almeida, E.A., Bainy, A.C.D., Loureiro, A.P.M., Medeiros, M.H.G., Di Mascio, P., 2003.DNA and lipid damage in the brown mussel Perna perna from a contaminated

site. Bull. Environ. Contam. Toxicol. 71, 270–275.Almeida, E.A., Miyamoto, S., Bainy, A.C.D., Medeiros, M.H.G., Di Mascio, P., 2004. Pro-

tective effect of phospholipid hydroperoxide glutathione peroxidase (PHGPx)against lipid peroxidation in mussels Perna perna exposed to different metals.Mar. Pollut. Bull. 49, 386–392.

Almeida, E.A., Bainy, A.C.D., Dafre, A.L., Gomes, O.F., Medeiros, M.H.G., Di Mascio, P.,2005. Oxidative stress in digestive gland and gill of the brown mussel (Pernaperna) exposed to air and re-submersed. J. Exp. Mar. Biol. Ecol. 318, 21–30.

Bando, I., Reus, M.I.S., Andres, D., Cascales, M., 2005. Endogenous antioxidantdefence system in rat liver following mercury chloride oral intoxication. J.Biochem. Mol. Toxicol. 19, 154–161.

Barim, O., Karatepe, M., 2010. The effects of pollution on the vitamins A, E, C,�-carotene contents and oxidative stress of the fresh water crayfish, Astacusleptodactylus. Ecotoxicol. Environ. Saf. 73, 138–142.

Battacharya, A., Battacharya, S., 2007. Induction of oxidative stress by As inClarias batrachus: involvement of peroxissomes. Ecotoxicol. Environ. Saf. 66,178–187.

Bokara, K.K., Brown, E., McCormick, R., Yallapragada, P.R., Rajanna, S., Bettaiya, R.,2008. Lead-induced increase in antioxidant enzymes and lipid peroxidationproducts in developing rat brain. Biometals 21, 9–16.

Borkovic, S.S., Saponjic, J.S., Pavlovic, S.Z., Blagojevic, D.P., Milosevic, S.M., Kovacevic,T.B., Radojicic, R.M., Spasic, M.B., Zikic, R.V., Saicic, Z.S., 2005. The activity ofantioxidant defence enzymes in mussels (Mytilus galloprovincialis) from theAdriatic Sea. Comp. Biochem. Physiol. C 141, 366–374.

Borkovic, S.S., Pavlovic, S.Z., Kovacevic, T.B., Stajn, A.S., Petrovic, V.M., Saicic, Z.S.,2008. Antioxidant defence enzyme activities in hepatopancreas, gills and mus-cle of Spiny cheek crayfish (Orconectes limosus) from the River Danube. Comp.Biochem. Physiol. C 147, 122–128.

Canesi, L., Viarengo, A., Leonzio, C., Filippelli, M., Gallo, G., 1999. Heavy metals andglutathione metabolism in mussel tissues. Aquat. Toxicol. 46, 67–76.

Cheung, K.C., Poon, B.H.T., Lan, C.Y., Wong, M.H., 2003. Assessment of metal andnutrient concentrations in river water and sediment collected from the cities inthe Pearl River Delta, South China. Chemosphere 52, 1431–1440.

Claiborne, A., 1984. In: Greenwald, R.A. (Ed.), Handbook of Methods for OxygenRadical Research. C.R.C. Press Inc., Boca Raton.

Cossu, C., Doyotte, A., Jacquin, M.C., Babut, M., Exinger, A., Vasseur, P., 1997.Glutathione-reductase, selenium-dependent glutathione peroxidase, glu-

tathione levels and lipid peroxidation in freshwater bivalves, Unio timidus, asa biomarkers of aquatic contamination in field studies. Ecotoxicol. Environ. Saf.38, 122–131.

Cossu, C., Doyotte, A., Babut, M., Exinger, A., Vasseur, P., 2000. Antioxidant biomark-ers in freshwater bivalves, Unio tumidus, in response to different contaminationprofiles of aquatic sediments. Environ. Saf. 45, 106–121.

Darlington, R.B., Weinsberg, S., Walberg, H., 1973. Canonical variate analysis andrelated techniques. Rev. Edu. Res. 43, 433–454.

Dinneen, L.C., Blakesley, B.C., 1973. A generator for the sampling distribution of theMann Whitney U statistic. Appl. Stat. 22, 269–273.

Doyen, P., Vasseur, P., Rodius, F., 2006. Identification, sequencing and expressionof selenium–dependent glutathione peroxidase transcript in the freshwaterbivalve Unio tumidus exposed to Aroclor 1254. Comp. Biochem. Physiol. C 144,122–129.

Desai, I.D., 1984. Vitamin E analysis methods for animal tissues. Methods Enzymol.105, 138–147.

Dragun, Z., Erk, M., Raspor, B., Ivankovic, D., Pavicic, J., 2004. Metal and metallothi-onein level in the heat-treated cytosol of gills of transplanted mussels Mytilusgalloprovincialis Lmk. Environ. Int. 30, 1019–1025.

Eaton, D.L., Stacey, N.H., Wong, K.L., Klaassen, C.D., 1980. Dose-response effects ofvarious metal ions on rat liver, metallothionein, glutathione, heme oxygenaseand cytochrome P-450. Toxicol. Appl. Pharmacol. 55, 393–402.

Ellman, G.L., 1959. Tissue sulfhydryl groups. Arch. Biochem. Biophys. 82, 70–77.Fernández, B., Campillo, J.A., Martínez-Gómez, C., Benedicto, J., 2010. Antioxidant

responses in gills of mussel (Mytilus galloprovincialis) as biomarkers of envi-ronmental stress along the Spanish Mediterranean coast. Aquat. Toxicol. 99,186–197.

Glatzle, D., Vulliemuier, J.P., Weber, F., Decker, K., 1974. Glutathione reductase testwith whole blood a convenient procedure for the assessment of the riboflavinstatus in humans. Experientia 30, 665–667.

Habig, W.H., Pubst, M.J., Jakoby, W.B., 1974. Glutathione S-transferase. J. Biol. Chem.249, 7130–7139.

Halliwell, B., Gutteridge, J.M.C., 1999. Free Radicals in Biology and Medicine, 3rd ed.Oxford University Press, Oxford.

Hansen, B.H., Romma, S., Garmo, O.A., Pedersen, S.A., Olsvik, P.A., Andersen,R.A., 2007. Induction and activity of oxidative stress–related proteins duringwaterborne Cd/Zn–exposure in brown trout (Salmo trutta). Chemosphere 67,2241–2249.

ICPDR, 2006. Water Quality in the Danube River Basin. TNMN Yearbook 2006,Vienna.

Jing, G., Li, Y., Xie, L., Zhang, R., 2006. Metal accumulation and enzyme activitiesin gills and digestive gland of pearl oyster (Pinctada fucata) exposed to copper.Comp. Biochem. Physiol. C 144, 184–190.

Kovarova, J., Svobodova, Z., 2009. Can thiol compounds be used as biomarkers ofaquatic ecosystem contamination by cadmium? Interdisc. Toxicol. 2, 177–183.

gical I

L

L

L

L

L

M

M

M

M

P

P

P

P

R

R

R

S. Borkovic-Mitic et al. / Ecolo

abieniec, M., Gabryelak, T., 2007. Antioxidative and oxidative changes in digestivegland cells of freshwater mussels Unio tumidus caused by selected pheno-lic compounds in the presence of H2O2 or Cu2+ ions. Toxicol. In Vitro 21,146–156.

etelier, M.E., Lepe, A.M., Faúdez, M., Salazar, J., Marí, R., Aracena, P., Speisky, H.,2005. Possible mechanisms underlying copper-induced damage in biologicalmembranes leading to cellular toxicity. Chem. Biol. Interact. 151, 71–82.

ionetto, M.G., Caricato, R., Giordano, M.E., Pascariello, M.F., Marinosci, L., Schettino,T., 2003. Integrated use of biomarkers (acetylcholineesterase and antioxidantenzyme activities) in Mytilus galloprovincialis and Mullus barbatus in an Italiancoastal marine area. Mar. Pollut. Bull. 46, 324–330.

ivingstone, D.R., 2001. Contaminated-stimulated reactive oxygen species produc-tion and oxidative damage in aquatic organisms. Mar. Pollut. Bull. 42, 656–666.

owry, O.H., Rosebrough, N.L., Farr, A.L., Randall, R.I., 1951. Protein measurementwith Folin phenol reagent. J. Biol. Chem. 193, 265–275.

anduzio, H., Monsinjon, T., Galap, C., Leboulenger, F., Rocher, B., 2004. Seasonalvariations in antioxidant defences in the blue mussels Mytilus edulis collectedfrom a polluted area: major contributions in gills of an inducible isoform ofCu/Zn-superoxide dismutase and of glutathione S-transferase. Aquat. Toxicol.70, 83–93.

aria, V.L., Bebianno, M.J., 2011. Antioxidant and lipid peroxidation responses inMytilus galloprovincialis exposed to mixtures of benzo(a)pyrene and copper.Comp. Biochem. Physiol. C 154, 56–63.

arigómez, I., Soto, M., Cajaraville, M.P., Angulo, E., Giamberini, L., 2002. Cellular andsubcellular distribution of metals in molluscs. Microsc. Res. Tech. 56, 358–392.

isra, H.P., Fridovich, I., 1972. The role of superoxide anion in the autoxidationof epinephrine and simple assay for superoxide dismutase. J. Biol. Chem. 247,3170–3175.

aunovic, M.M., Borkovic, S.S., Pavlovic, S.Z., Saicic, Z.S., Cakic, P.D., 2008. The resultsof 2006 Sava Survey-aquatic macroinvertebrates. Arch. Biol. Sci., Belgrade 60,265–271.

avlovic, S.Z., Borkovic, S.S., Kovacevic, T.B., Ognjanovic, B.I., Zikic, R.V., Stajn, A.S.,Saicic, Z.S., 2008. Antioxidant defense enzyme activities in the liver of red mullet(Mullus barbatus L.) from the Adriatic Sea: The effects of locality and season.Fresenius Environ. Bull. 17, 558–563.

avlovic, S.Z., Borkovic Mitic, S.S., Radovanovic, T.B., Perendija, B.R., Despotovic, S.G.,Gavric, J.P., Saicic, Z.S., 2010. Seasonal variations of the activity of antioxidantdefense enzymes in the red mullet (Mullus barbatus l.) from the Adriatic Sea.Mar. Drugs 8 (3), 413–428.

ipe, R.K., Coles, J.A., Carissan, F.M.M., Ramanathan, K., 1999. Copper inducedimmunomodulation in the marine mussel. Mytilus edulis. Aquat. Toxicol 46,43–54.

adhakrishnan, M., 2009. Effect of cadmium on catalase activity in four tis-sues of freshwater fish Heteropneustes fossilis (Bloch.). Int. J. Vet. Med. 7,1937–8165.

egoli, F., Principato, G., 1995. Glutathione, glutathione-dependent and antioxi-dant enzymes in mussel, Mytilus galloprovincialis, exposed to metals under fieldand laboratory conditions: Implications for the use of biochemical biomarkers.Aquat. Toxicol. 31, 143–164.

HMZ, 2006. Annual Program of the Republic Hydrometeorological Service of Serbia.

ndicators 32 (2013) 212– 221 221

Roméo, M., Bennani, N., Gnassia-Barelli, M., Lafaurie, M., Girard, J.P., 2000. Cadmiumand copper display different responses towards oxidative stress in the kidneyof the sea bass Dicentrarchus labrax. Aquat. Toxicol. 48, 185–194.

Rossi, M.A., Cecchini, G., Dianzani, M.M., 1983. Glutathione peroxidase, glutathionereductase and glutathione transferase in two different hepatomas and in normalliver. IRCS Med. Sci. Biochem. 11, 805.

Roling, J.A., Baldwin, W.S., 2006. Alterations in hepatic gene expression by trivalentchromium in Fundulus heteroclitus. Mar. Environ. Res. 62, 122–127.

Takada, Y., Noguchit, T., Kayiyama, M., 1982. Superoxide dismutase in various tissuesfrom rabbits bearing the Vx-2 carcinoma in the maxillary sinus. Cancer Res. 42,4233–4235.

Tamura, M., Oschino, N., Chance, B., 1982. Some characteristics of hydrogen andalkyl-hydroperoxides metabolizing systems in cardiac tissue. J. Biochem. 92,1019–1031.

Tran, D., Fournier, E., Durrieu, G., Massabuau, J.C., 2004. Copper detection in theAsiatic clam Corbicula fluminea: optimum valve closure response. Aquat. Toxicol.66, 333–343.

Türkmen, M., Ciminli, C., 2007. Determination of metals in fish and mussel speciesby inductively coupled plasma-atomic emission spectrometry. Food Chem. 103,670–675.

Valko, M., Morris, H., Cronin, M.T.D., 2005. Metals, toxicity and oxidative stress. Curr.Med. Chem. 12, 1161–1208.

Van der Oost, R., Beyer, J., Vermeulen, N.P.E., 2003. Fish bioaccumulation andbiomarkers in environmental risk assessment: a review. Environ. Toxicol.Pharmacol. 13, 57–149.

Ventura-Lima, J., Sandrini, J.Z., Ferreira-Cravo, M., Piedras, F.R., Moraes, T.B., Fattorini,D., Notti, A., Regoli, F., Geracitano, L.A., Marins, L.F., Monserrat, J.M., 2007. Toxi-cological responses in Laeonereis acuta (Annelida, Polychaeta) after As exposure.Environ. Int. 33, 559–564.

Vidal-Linán, L., Bellas, J., Campillo, J.A., Beiras, R., 2010. Integrated use of antiox-idant enzymes in mussels, Mytilus galloprovincialis, for monitoring pollutionin highly productive coastal areas of Galicia (NW Spain). Chemosphere 78,265–272.

Vlahogianni, T., Dassenakis, M., Scoullos, M.J., Valavanidis, A., 2007. Integrated use ofbiomarkers (superoxide dismutase, catalase and lipid peroxidation) in musselsMytilus galloprovincialis for assessing heavy metals’ pollution in coastal areasfrom the Saronikos Gulf of Greece. Mar. Pollut. Bull. 54, 1361–1371.

WFD, 2000. Water Framework Directive – Directive of European Parliament and ofthe Council 2000/60/EC – Establishing a Framework for Community Action inthe Field of Water Policy.

Xie, L., Flippin, J.L., Deighton, N., Funk, D.H., Dickey, D.A., Buchwalter, D.B., 2009.Mercury(II) bioaccumulation and antioxidant physiology in four aquatic insects.Environ. Sci. Technol. 43, 934–940.

Yap, C.K., Hatta, Y., Edward, F.B., Tan, S.G., 2008. Distribution of heavy metal con-centrations (Cd, Cu, Ni, Fe and Zn) in the different soft tissues and shells of wild

mussels Perna viridis collected from Bagan Tiang and Kuala Kedah. Malays. Appl.Biol. 37, 1–10.

Zhang, Y., Song, J., Yuan, H., Xu, Y., He, Z., Duan, L., 2010. Biomarker responsesin the bivalve (Chlamys farreri) to exposure of the environmentally relevantconcentrations of lead, mercury, copper. Environ. Toxicol. Pharmacol. 30, 19–25.