Roberta Klobucar - Academia.edu (original) (raw)

Papers by Roberta Klobucar

Journal of Hazardous Materials, Nov 1, 2016

Multilevel ecotoxicity assessment of environmentally relevant bisphenol A concentrations using th... more Multilevel ecotoxicity assessment of environmentally relevant bisphenol A concentrations using the soil invertebrate Eisenia fetida SANJA BABIĆ a1 , JOSIP BARIŠIĆ a1 , ANA BIELEN b* , IVANA BOŠNJAK c* , ROBERTA SAUERBORN KLOBUĈAR d , IVANA UJEVIĆ e , IVANĈICA STRUNJAK-PEROVIĆ a , NATALIJA TOPIĆ POPOVIĆ a , ROZELINDRA ĈOŢ-RAKOVAC a a

Waste water treatment plants (WWTPs) are important point sources of a broad range of xenobiotics ... more Waste water treatment plants (WWTPs) are important point sources of a broad range of xenobiotics in the aquatic environment. Once released from WWTPs, xenobiotics represent a potential risk to environment, but also to human health. Since it is very hard to predict their possible impact on different levels of biological organization, it is necessary to use "early warning" biomarkers that can provide informations on potential environmental impact. Zebrafish embryos are frequently used organisms in ecotoxicology studies due to their short embryonic ontogenesis and transparent chorion. The fish embryo test (FET), as a substitute for acute toxicity with adult zebrafish, is a great biomarker in toxicity testing of pollutants that are residues from incomplete elimination in WWTPs. Screening sub-lethal and lethal endpoints after exposure to wastewater included coagulation of embryos, presence of somites, tail detachment, heart functioning, blood circulation, pigmentation, formation of edema and developmental retardation. Zebrafish embryos also possess multixenobiotic resistance mechanism (MXR) mediated by ABC transport proteins that acts as a protective barrier against the cell uptake and accumulation of potentially toxic compounds dissolved in the water. MXR mechanism can be modified by the presence of a wide range of xenobiotics frequently present in wastewaters (pharmaceuticals, chemicals used in industry and agriculture, personal care producs). Concentration of model fluorescent substrate in the embryo after exposure to environmental samples, give us an insight into the degree of inhibition and accumulation of xenobiotics from wastewater in the whole embryo. The integration of embryotoxicity and MXR creates a sensitive tool for the evaluation of early developmental responses of zebrafish to xenobiotics present in wastewaters on whole organism level, but also on the cellular level. These responses help us to understand better possible toxic effects of wastewater effluents on aquatic organisms.

In many organisms, the multixenobiotic resistance mechanism (MXR) is mediated by the activity of ... more In many organisms, the multixenobiotic resistance mechanism (MXR) is mediated by the activity of ABC transporters that bind and actively effl ux different toxic substrates from cells. This study attempted to identify MXR-related genes in the earthworm Eisenia fetida and compare the impact of the selected modulators, including verapamil, cyclosporine A, MK571, probenecid, orthovanadate, bisphenol A, and snow samples on the earthworm’s MXR. To confi rm the presence of MXR-reversing agents in E. fetida, we measured the accumulation of model substrates rhodamine B and rhodamine 123 in the body tissue of an adult earthworm. Experiments performed using the fi lter paper contact test showed that all of the tested modulators and environmental samples signifi cantly inhibited transport activity of the model substrates. Furthermore, partial mRNA sequence coding for P-glycoprotein (P-gp/Abcb1) was identifi ed and showed a high amino acid identity (up to 78 %) with homologues from different organisms. We could say that the ABC transporters are involved in various specifi c mechanisms that help earthworms to survive in a polluted environment and that their effi ciency can become compromised by environmental contamination.

Opisana je uloga i djelovanje probiotika, njihov utjecaj na ribe, nacini uporabe probiotika. Opis... more Opisana je uloga i djelovanje probiotika, njihov utjecaj na ribe, nacini uporabe probiotika. Opisani su rezultati istraživanja ucinka Lactobacillus rhamnosus na kalifornijsku pastrvu.

Drug and Chemical Toxicology, 2019

To address and to compare the respective impact of gold and silver nanoparticles (Au and Ag NPs) ... more To address and to compare the respective impact of gold and silver nanoparticles (Au and Ag NPs) in soil invertebrate, the earthworm Eisenia fetida was exposed to soil containing 2, 10, and 50 mg/kg of Au and Ag in both nanoparticulate and ionic forms for 10 days. Both metal NPs were 2-15 times less bioavailable than their ionic forms, and displayed similar transfer coefficients from soil to earthworm tissues. Both metal NPs triggered the onset of an oxidative stress as illustrated by increased glutathione S-transferase levels, decreased catalase levels, and increased malondialdehyde concentrations. Protein carbonylation distinguished the nanoparticular from the ionic forms as its increase was observed only after exposure to the highest concentration of both metal NPs. Au and Ag NPs triggered DNA modifications even at the lowest concentration, and both repressed the expression of genes involved in the general defense and stress response at high concentrations as did their ionic counterparts. Despite the fact that both metal NPs were less bioavailable than their ionic forms, at equivalent concentrations accumulated within earthworms tissues they exerted equal or higher toxic potential than their ionic counterparts. Capsule: At equivalent concentrations accumulated within earthworm tissues Au and Ag NPs exert equal or higher toxic potential than their ionic forms.

Arhiv Za Higijenu Rada I Toksikologiju, Jun 16, 2010

One of the most intriguing defence strategies which aquatic organisms developed through evolution... more One of the most intriguing defence strategies which aquatic organisms developed through evolution is multixenobiotic resistance (MXR). The key mediators of MXR activity are ATP-binding cassette (ABC) transport proteins. They provide resistance of aquatic organisms by binding xenobiotics and extruding them from cells in an energy-dependent manner. Since Cyprinid fi sh species are common target in freshwater biomonitoring programs, we have studied the presence of two main MDR/MXR effl ux transporters Pglycoprotein (Pgp, Abcb1) and MRP-like protein(s) (Abcc) in the liver of fi ve Cyprinid species: common carp, European chub, sneep, barbel, and silver prussian carp. Their presence was evaluated on the mRNA and protein level. Various pairs of primers were designed to clone homologous fragments of MXR-related genes. At the protein level, we used Western blotting with specifi c monoclonal antibodies against human Pgp (Abcb1, Ab C219), MRP1 (Abcc1; Ab MRPm6) or MRP2 (Abcc2; Ab M2I-4). Transcripts of both key types of MXR transporters were identifi ed in all species examined and here we provide the phylogenetic analysis of new partial sequences. Immunochemical determinations with mammalian antibodies failed to identify the presence of MRP(s), but Pgp expression was found in all fi ve Cyprinid species. These results support that MXR is a defence system mediated by both Pgp and MRP types of ABC transport proteins.

The multixenobiotic resistance (MXR) defence system is mediated by different effl ux transporters... more The multixenobiotic resistance (MXR) defence system is mediated by different effl ux transporters and its activity has been confi rmed in many organisms, both prokaryotes and eukaryotes. MXR transporters confer resistance by preventing xenobiotics from entering the cells and by their extrusion into the extracellular environment. Chemicals known as chemosensitizers (inhibitors, modulators) can inhibit MXR function and thus represent specifi c environmental contaminants. A wide range of pesticides have been shown to act as MXR inhibitors. Presence of chemosensitizers in the environment may increase the absorption of xenobiotics and consequently their cellular toxic infl uence in aquatic and soil organisms. In this study, MXR activity and its inhibition have been measured using a dye exclusion assay in amphipod Gammarus fossarum and earthworm Eisenia fetida in order to assess the chemosensitizing potential of imidacloprid (IMI) and its transformation product 6-chloronicotinic acid (6CNA). In amphipods, 6CNA was proved to be a potent inhibitor of MXR at low concentrations, while IMI presented no signifi cant inhibition compared to control. Interestingly, co-exposure of amphipods to IMI or 6CNA and the common fungicide copper sulphate resulted in a greater additive inhibition effect of MXR activity. Earthworms exposed to tenfold lower concentration of IMI and 6CNA (because higher concentrations were lethal) did not exhibit inhibition of effl ux pumps. These results highlight the need of further investigation of the effects of neonicotinoids as chemosensitizers, as they enhance the toxicity of other co-occurring contaminants and may thus have signifi cant consequences for aquatic and soil organisms.

NATO science for peace and security series, 2015

There is an enormous amount of new chemicals emerging every day with potential adverse effects fo... more There is an enormous amount of new chemicals emerging every day with potential adverse effects for humans and environment. To assess these chemicals we need cost effective and reliable biological tools. Here we present in detail one of many bioassays suited for assessing chemical poisoning in the environment. This is a terrestrial isopod single-species test. Advantages of this test with terrestrial isopods are its flexibility in terms of exposure duration and versatile biomarker selection. By alternating test duration, one can test also those substances which are with moderate or low toxic potential; while a variety of biomarkers at different levels of biological complexity increase the relevance of tests results. In addition to laboratory single-species tests, terrestrial isopods could also be used for biomonitoring of pollutants. So far, this was thoroughly assessed in case of metal pollution, although isopods have a potential to be used also for biomonitoring of some organic substances and metal based nanoparticles. This is usually not the case in other standardised ecotoxicity tests species. In addition, we discuss that at present, we do not need completely new tests for emerging substances like new generations pesticides, personal care products and products of nanotechnologies, but is sufficient to adopt and modify existing test protocols.

Frontiers in Microbiology, Jan 12, 2023

Several species in the genus Legionella are known to cause an acute pneumonia when the aerosols c... more Several species in the genus Legionella are known to cause an acute pneumonia when the aerosols containing the bacteria from man-made water systems are inhaled. The disease is usually caused by Legionella pneumophila, but other species have been implicated in the infection. The disease is frequently manifested as an outbreak, which means several people are affected when exposed to the common source of Legionella contamination. Therefor environmental surveillance which includes isolation and identification of Legionella is performed routinely. However, usually no molecular or genomebased methods are employed in further characterization of the isolates during routine environmental monitoring. During several years of such monitoring, isolates from different geographical locations were collected and 39 of them were sequenced by hybrid de novo approach utilizing short and long sequencing reads. In addition, the isolates were typed by standard culture and MALDI-TOF method. The sequencing reads were assembled and annotated to produce high-quality genomes. By employing discriminatory genome typing, four potential new species in the Legionella genus were identified, which are yet to be biochemically and morphologically characterized. Moreover, functional annotations concerning virulence and antimicrobial resistance were performed on the sequenced genomes. The study contributes to the knowledge on little-known non-pneumophila species present in man-made water systems and establishes support for future genetic relatedness studies as well as understanding of their pathogenic potential.

Magnetic Resonance Imaging (MRI) is increasingly used in biology and the appearance of such imagi... more Magnetic Resonance Imaging (MRI) is increasingly used in biology and the appearance of such imaging and structural findings devoted to endangered marine bivalves shows the recent keen interest in these research techniques. New imaging techniques are ideal for understanding the normal form of soft structures (e.g. gonad, stomach, digestive gland, muscle, gills), and identifying anatomical positions and landmarks of structures in vivo. Because of its biological importance, endangered bivalve mollusks are the subject of much research in physiology. In terms of protection of species, it seemed necessary to perform a preliminary technological evaluation of the MRI possibilities. Aim of this research was to make a preliminary exploration of the possibilities and limits of MRI for assessing anatomical structures and gonad development of the date mussel, Lithophaga lithophaga L., an endangered bivalve from Adriatic sea. This paper presents a new imaging technique used in comparative morphol...

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2006

Measurement of the modulation of accumulation rate of model P-glycoprotein (Pgp) substrates has b... more Measurement of the modulation of accumulation rate of model P-glycoprotein (Pgp) substrates has been a well established methodology for determination of the presence and activity of the multixenobiotic resistance (MXR) defence mechanism in aquatic invertebrates. Most studies have been focused on the gill tissue of various bivalves as a primary compartment for this type of measurements. In this study, we evaluated the potential of measuring the accumulation rate of a fluorescent model Pgp substrate rhodamine B (RB) in haemolymph, plasma and haemocytes of the freshwater painter's mussel (Unio pictorum) as additional potentially useful compartments. The obtained results demonstrated several important advantages of the determination of Pgp mediated MXR transport activity in haemolymph over determinations in gill tissue. The overall MXR response correlated well with the level of Pgp activity simultaneously determined in gills. The method is more sensitive, the procedure is easier and less laborious, and repeated use of same individuals is possible. Finally--the approach is non-destructive, offering a potentially powerful biomarker and research tool for studies directed to the evaluation of ecotoxicological importance of MXR defence and the presence of MXR inhibitors in the environment.

Environmental Chemistry, 2016

Environmental context Various UV-filtering chemicals are added to sunscreens in order to protect ... more Environmental context Various UV-filtering chemicals are added to sunscreens in order to protect humans from the harmful effects of the sun. As a consequence of disinfection processes in swimming pools, sunscreen components may be chlorinated and change their structure and properties, leading to derivatives with higher toxicity. The safety of sunscreen components as well as that of their transformation products during their use requires further study. In this work is presented a synthesis pathway for the UV filter hexyl 2-(4-diethylamino-2-hydroxybenzoyl)benzoate (DHHB) and its chlorinated by-products in order to investigate the transformation behaviour and toxicity changes of DHHB during chlorination disinfection treatment. Acute toxicity was measured using standardised tests with aquatic model organisms. The potency of DHHB was compared with other benzophenone-like UV filters tested in the same experimental set-up. The toxicity of chlorinated compounds tested with photobacteria wa...

Journal of Hazardous Materials, Nov 1, 2016

Multilevel ecotoxicity assessment of environmentally relevant bisphenol A concentrations using th... more Multilevel ecotoxicity assessment of environmentally relevant bisphenol A concentrations using the soil invertebrate Eisenia fetida SANJA BABIĆ a1 , JOSIP BARIŠIĆ a1 , ANA BIELEN b* , IVANA BOŠNJAK c* , ROBERTA SAUERBORN KLOBUĈAR d , IVANA UJEVIĆ e , IVANĈICA STRUNJAK-PEROVIĆ a , NATALIJA TOPIĆ POPOVIĆ a , ROZELINDRA ĈOŢ-RAKOVAC a a

Waste water treatment plants (WWTPs) are important point sources of a broad range of xenobiotics ... more Waste water treatment plants (WWTPs) are important point sources of a broad range of xenobiotics in the aquatic environment. Once released from WWTPs, xenobiotics represent a potential risk to environment, but also to human health. Since it is very hard to predict their possible impact on different levels of biological organization, it is necessary to use "early warning" biomarkers that can provide informations on potential environmental impact. Zebrafish embryos are frequently used organisms in ecotoxicology studies due to their short embryonic ontogenesis and transparent chorion. The fish embryo test (FET), as a substitute for acute toxicity with adult zebrafish, is a great biomarker in toxicity testing of pollutants that are residues from incomplete elimination in WWTPs. Screening sub-lethal and lethal endpoints after exposure to wastewater included coagulation of embryos, presence of somites, tail detachment, heart functioning, blood circulation, pigmentation, formation of edema and developmental retardation. Zebrafish embryos also possess multixenobiotic resistance mechanism (MXR) mediated by ABC transport proteins that acts as a protective barrier against the cell uptake and accumulation of potentially toxic compounds dissolved in the water. MXR mechanism can be modified by the presence of a wide range of xenobiotics frequently present in wastewaters (pharmaceuticals, chemicals used in industry and agriculture, personal care producs). Concentration of model fluorescent substrate in the embryo after exposure to environmental samples, give us an insight into the degree of inhibition and accumulation of xenobiotics from wastewater in the whole embryo. The integration of embryotoxicity and MXR creates a sensitive tool for the evaluation of early developmental responses of zebrafish to xenobiotics present in wastewaters on whole organism level, but also on the cellular level. These responses help us to understand better possible toxic effects of wastewater effluents on aquatic organisms.

In many organisms, the multixenobiotic resistance mechanism (MXR) is mediated by the activity of ... more In many organisms, the multixenobiotic resistance mechanism (MXR) is mediated by the activity of ABC transporters that bind and actively effl ux different toxic substrates from cells. This study attempted to identify MXR-related genes in the earthworm Eisenia fetida and compare the impact of the selected modulators, including verapamil, cyclosporine A, MK571, probenecid, orthovanadate, bisphenol A, and snow samples on the earthworm’s MXR. To confi rm the presence of MXR-reversing agents in E. fetida, we measured the accumulation of model substrates rhodamine B and rhodamine 123 in the body tissue of an adult earthworm. Experiments performed using the fi lter paper contact test showed that all of the tested modulators and environmental samples signifi cantly inhibited transport activity of the model substrates. Furthermore, partial mRNA sequence coding for P-glycoprotein (P-gp/Abcb1) was identifi ed and showed a high amino acid identity (up to 78 %) with homologues from different organisms. We could say that the ABC transporters are involved in various specifi c mechanisms that help earthworms to survive in a polluted environment and that their effi ciency can become compromised by environmental contamination.

Opisana je uloga i djelovanje probiotika, njihov utjecaj na ribe, nacini uporabe probiotika. Opis... more Opisana je uloga i djelovanje probiotika, njihov utjecaj na ribe, nacini uporabe probiotika. Opisani su rezultati istraživanja ucinka Lactobacillus rhamnosus na kalifornijsku pastrvu.

Drug and Chemical Toxicology, 2019

To address and to compare the respective impact of gold and silver nanoparticles (Au and Ag NPs) ... more To address and to compare the respective impact of gold and silver nanoparticles (Au and Ag NPs) in soil invertebrate, the earthworm Eisenia fetida was exposed to soil containing 2, 10, and 50 mg/kg of Au and Ag in both nanoparticulate and ionic forms for 10 days. Both metal NPs were 2-15 times less bioavailable than their ionic forms, and displayed similar transfer coefficients from soil to earthworm tissues. Both metal NPs triggered the onset of an oxidative stress as illustrated by increased glutathione S-transferase levels, decreased catalase levels, and increased malondialdehyde concentrations. Protein carbonylation distinguished the nanoparticular from the ionic forms as its increase was observed only after exposure to the highest concentration of both metal NPs. Au and Ag NPs triggered DNA modifications even at the lowest concentration, and both repressed the expression of genes involved in the general defense and stress response at high concentrations as did their ionic counterparts. Despite the fact that both metal NPs were less bioavailable than their ionic forms, at equivalent concentrations accumulated within earthworms tissues they exerted equal or higher toxic potential than their ionic counterparts. Capsule: At equivalent concentrations accumulated within earthworm tissues Au and Ag NPs exert equal or higher toxic potential than their ionic forms.

Arhiv Za Higijenu Rada I Toksikologiju, Jun 16, 2010

One of the most intriguing defence strategies which aquatic organisms developed through evolution... more One of the most intriguing defence strategies which aquatic organisms developed through evolution is multixenobiotic resistance (MXR). The key mediators of MXR activity are ATP-binding cassette (ABC) transport proteins. They provide resistance of aquatic organisms by binding xenobiotics and extruding them from cells in an energy-dependent manner. Since Cyprinid fi sh species are common target in freshwater biomonitoring programs, we have studied the presence of two main MDR/MXR effl ux transporters Pglycoprotein (Pgp, Abcb1) and MRP-like protein(s) (Abcc) in the liver of fi ve Cyprinid species: common carp, European chub, sneep, barbel, and silver prussian carp. Their presence was evaluated on the mRNA and protein level. Various pairs of primers were designed to clone homologous fragments of MXR-related genes. At the protein level, we used Western blotting with specifi c monoclonal antibodies against human Pgp (Abcb1, Ab C219), MRP1 (Abcc1; Ab MRPm6) or MRP2 (Abcc2; Ab M2I-4). Transcripts of both key types of MXR transporters were identifi ed in all species examined and here we provide the phylogenetic analysis of new partial sequences. Immunochemical determinations with mammalian antibodies failed to identify the presence of MRP(s), but Pgp expression was found in all fi ve Cyprinid species. These results support that MXR is a defence system mediated by both Pgp and MRP types of ABC transport proteins.

The multixenobiotic resistance (MXR) defence system is mediated by different effl ux transporters... more The multixenobiotic resistance (MXR) defence system is mediated by different effl ux transporters and its activity has been confi rmed in many organisms, both prokaryotes and eukaryotes. MXR transporters confer resistance by preventing xenobiotics from entering the cells and by their extrusion into the extracellular environment. Chemicals known as chemosensitizers (inhibitors, modulators) can inhibit MXR function and thus represent specifi c environmental contaminants. A wide range of pesticides have been shown to act as MXR inhibitors. Presence of chemosensitizers in the environment may increase the absorption of xenobiotics and consequently their cellular toxic infl uence in aquatic and soil organisms. In this study, MXR activity and its inhibition have been measured using a dye exclusion assay in amphipod Gammarus fossarum and earthworm Eisenia fetida in order to assess the chemosensitizing potential of imidacloprid (IMI) and its transformation product 6-chloronicotinic acid (6CNA). In amphipods, 6CNA was proved to be a potent inhibitor of MXR at low concentrations, while IMI presented no signifi cant inhibition compared to control. Interestingly, co-exposure of amphipods to IMI or 6CNA and the common fungicide copper sulphate resulted in a greater additive inhibition effect of MXR activity. Earthworms exposed to tenfold lower concentration of IMI and 6CNA (because higher concentrations were lethal) did not exhibit inhibition of effl ux pumps. These results highlight the need of further investigation of the effects of neonicotinoids as chemosensitizers, as they enhance the toxicity of other co-occurring contaminants and may thus have signifi cant consequences for aquatic and soil organisms.

NATO science for peace and security series, 2015

There is an enormous amount of new chemicals emerging every day with potential adverse effects fo... more There is an enormous amount of new chemicals emerging every day with potential adverse effects for humans and environment. To assess these chemicals we need cost effective and reliable biological tools. Here we present in detail one of many bioassays suited for assessing chemical poisoning in the environment. This is a terrestrial isopod single-species test. Advantages of this test with terrestrial isopods are its flexibility in terms of exposure duration and versatile biomarker selection. By alternating test duration, one can test also those substances which are with moderate or low toxic potential; while a variety of biomarkers at different levels of biological complexity increase the relevance of tests results. In addition to laboratory single-species tests, terrestrial isopods could also be used for biomonitoring of pollutants. So far, this was thoroughly assessed in case of metal pollution, although isopods have a potential to be used also for biomonitoring of some organic substances and metal based nanoparticles. This is usually not the case in other standardised ecotoxicity tests species. In addition, we discuss that at present, we do not need completely new tests for emerging substances like new generations pesticides, personal care products and products of nanotechnologies, but is sufficient to adopt and modify existing test protocols.

Frontiers in Microbiology, Jan 12, 2023

Several species in the genus Legionella are known to cause an acute pneumonia when the aerosols c... more Several species in the genus Legionella are known to cause an acute pneumonia when the aerosols containing the bacteria from man-made water systems are inhaled. The disease is usually caused by Legionella pneumophila, but other species have been implicated in the infection. The disease is frequently manifested as an outbreak, which means several people are affected when exposed to the common source of Legionella contamination. Therefor environmental surveillance which includes isolation and identification of Legionella is performed routinely. However, usually no molecular or genomebased methods are employed in further characterization of the isolates during routine environmental monitoring. During several years of such monitoring, isolates from different geographical locations were collected and 39 of them were sequenced by hybrid de novo approach utilizing short and long sequencing reads. In addition, the isolates were typed by standard culture and MALDI-TOF method. The sequencing reads were assembled and annotated to produce high-quality genomes. By employing discriminatory genome typing, four potential new species in the Legionella genus were identified, which are yet to be biochemically and morphologically characterized. Moreover, functional annotations concerning virulence and antimicrobial resistance were performed on the sequenced genomes. The study contributes to the knowledge on little-known non-pneumophila species present in man-made water systems and establishes support for future genetic relatedness studies as well as understanding of their pathogenic potential.

Magnetic Resonance Imaging (MRI) is increasingly used in biology and the appearance of such imagi... more Magnetic Resonance Imaging (MRI) is increasingly used in biology and the appearance of such imaging and structural findings devoted to endangered marine bivalves shows the recent keen interest in these research techniques. New imaging techniques are ideal for understanding the normal form of soft structures (e.g. gonad, stomach, digestive gland, muscle, gills), and identifying anatomical positions and landmarks of structures in vivo. Because of its biological importance, endangered bivalve mollusks are the subject of much research in physiology. In terms of protection of species, it seemed necessary to perform a preliminary technological evaluation of the MRI possibilities. Aim of this research was to make a preliminary exploration of the possibilities and limits of MRI for assessing anatomical structures and gonad development of the date mussel, Lithophaga lithophaga L., an endangered bivalve from Adriatic sea. This paper presents a new imaging technique used in comparative morphol...

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2006

Measurement of the modulation of accumulation rate of model P-glycoprotein (Pgp) substrates has b... more Measurement of the modulation of accumulation rate of model P-glycoprotein (Pgp) substrates has been a well established methodology for determination of the presence and activity of the multixenobiotic resistance (MXR) defence mechanism in aquatic invertebrates. Most studies have been focused on the gill tissue of various bivalves as a primary compartment for this type of measurements. In this study, we evaluated the potential of measuring the accumulation rate of a fluorescent model Pgp substrate rhodamine B (RB) in haemolymph, plasma and haemocytes of the freshwater painter's mussel (Unio pictorum) as additional potentially useful compartments. The obtained results demonstrated several important advantages of the determination of Pgp mediated MXR transport activity in haemolymph over determinations in gill tissue. The overall MXR response correlated well with the level of Pgp activity simultaneously determined in gills. The method is more sensitive, the procedure is easier and less laborious, and repeated use of same individuals is possible. Finally--the approach is non-destructive, offering a potentially powerful biomarker and research tool for studies directed to the evaluation of ecotoxicological importance of MXR defence and the presence of MXR inhibitors in the environment.

Environmental Chemistry, 2016

Environmental context Various UV-filtering chemicals are added to sunscreens in order to protect ... more Environmental context Various UV-filtering chemicals are added to sunscreens in order to protect humans from the harmful effects of the sun. As a consequence of disinfection processes in swimming pools, sunscreen components may be chlorinated and change their structure and properties, leading to derivatives with higher toxicity. The safety of sunscreen components as well as that of their transformation products during their use requires further study. In this work is presented a synthesis pathway for the UV filter hexyl 2-(4-diethylamino-2-hydroxybenzoyl)benzoate (DHHB) and its chlorinated by-products in order to investigate the transformation behaviour and toxicity changes of DHHB during chlorination disinfection treatment. Acute toxicity was measured using standardised tests with aquatic model organisms. The potency of DHHB was compared with other benzophenone-like UV filters tested in the same experimental set-up. The toxicity of chlorinated compounds tested with photobacteria wa...