Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associa... more Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associated with eutrophication (nutrient enrichment) and changes in hydrology. In this study we analysed the distribution of planktonic cyanobacteria in Uruguay and their toxins (microcystin, saxitoxin and cylindrospermopsin), working with an interagency team (OSE, DINAMA, IM, University of the Republic and IIBCE). An historical data base (n = 3061 for 64 ecosystems, years 1980-2014) was generated. Differences between lotic and lentic ecosystems were found in terms of chlorophyll a and nutrient concentrations, usually indicating eutrophication. Two geo-referenced maps for the country were generated with cyanobacteria biomass indicators and the most relevant toxin (microcystin), according to risk levels suggested by the World Health Organization for recreational waters. The areas of greatest risk of exposure were the reservoirs of large rivers (Uruguay and Río Negro) and Río de la Plata beaches....
KruK, Carla (1,2); Martínez, ana (3); Martínez de la esCalera, Gabriela (4); trinChin, roMina (5)... more KruK, Carla (1,2); Martínez, ana (3); Martínez de la esCalera, Gabriela (4); trinChin, roMina (5); Manta, Gastón (5); seGura, anGel M. (6); PiCCini, Claudia (4); brena, beatriz (7); Fabiano, GraCiela (3,8); Pirez, MaCarena (9); Gabito, lourdes (2); alCántara, iGnaCio (2); YanniCelli, beatriz (2) (1) instituto de eColoGía Y CienCias aMbientales, FaCultad de CienCias, udelar, Montevideo, uruGuaY (2) eColoGía FunCional de sisteMas aCuátiCos, Centro universitario reGional del este (Cure), udelar, roCha, uruGuaY. (3) direCCión naCional de reCursos aCuátiCos, la PaloMa, MGaP, roCha, uruGuaY. (4) dePartaMento de MiCrobioloGía, instituto de investiGaCiones biolóGiCas CleMente estable, MeC, Montevideo, uruGuaY,
Bulletin of Environmental Contamination and Toxicology, 2018
We analyzed the effects of stratification changes due to wind on the vertical cyanobacteria distr... more We analyzed the effects of stratification changes due to wind on the vertical cyanobacteria distribution and microcystin-LR concentrations in a reservoir and assessed the implications for water management. Under stratified conditions, the highest microcystin concentrations (up to 4.16 µg/L) and toxic cyanobacteria biovolume occurred in the epilimnion (~ 1 m). The lowest microcystin concentrations were between 0.02 and 1.28 µg/L and occurred in the hypolimnion (~ 20 m). A cold front passage associated with high wind velocities induced water column mixing, promoting the redistribution of microcystin-LR and cyanobacteria throughout the water column and increasing their concentrations in deeper zones. Microcystin-LR concentration was positively correlated with cyanobacteria biovolume (r = 0.747) and chlorophyll a concentration (r = 0.798). Changes in thermal profile due to wind would imply a greater challenge for drinking water treatment plants, since high cyanobacterial and microcystin concentrations could reach deep-water intakes. Keywords Stratification • Microcystin • Cyanobacteria • Reservoir • Bonete Thermal stratification is a physical mechanism that can affect water quality in lakes and reservoirs. Most of the
Blooms of Nostocales (Cyanobacteria) are thought to be invading subtropical and temperate water b... more Blooms of Nostocales (Cyanobacteria) are thought to be invading subtropical and temperate water bodies. According to nutrient stoichiometry and physiological differences between cyanobacterial groups, the replacement of non-heterocystous species by Nostocales is favored when dissolved inorganic nitrogen decreases. However, some studies have shown different trends. We used laboratory bioassays to evaluate the concomitant effects of light and nutrient enrichment on phytoplankton assemblages dominated by non-heterocystous filamentous cyanobacteria. Three nutrient conditions (no addition, addition of phosphate, and addition of nitrate and phosphate) and two light intensities (40 and 80 lmol photon m-2 s-1) were assayed. Nostocales replaced or co-dominated with non-heterocystous species in all treatments by the end of the study. The shift in community composition towards Nostocales dominance led to an increase in species richness, which suggests that species with different eco-physiological traits may have differential impacts on diversity. The highest saxitoxin concentrations were measured in no addition treatments, which could link production to nutritional stress. Nostocales featured high phenotypic plasticity in terms of changes in average trichome Handling editor: Boping Han
Single domain heavychain binders (nanobodies) obtained from camelid antibody libraries hold a gre... more Single domain heavychain binders (nanobodies) obtained from camelid antibody libraries hold a great promise for immunoassay development. However, there is no simple method to select the most valuable nanobodies from the crowd of positive clones obtained after the initial screening. In this paper, we describe a novel nanobody-based platform that allows comparison of the reactivity of hundreds of clones with the labeled antigen, and identifies the best nanobody pairs for twosite immunoassay development. The output clones are biotinylated in vivo in 96-well culture blocks and then used to saturate the biotin binding capacity of avidin coated wells. This standardizes the amount of captured antibody allowing their sorting by ranking their reactivity with the labeled antigen. Using human soluble epoxide hydrolase (sEH) as a model antigen, we were able to classify 96 clones in four families and confirm this classification by sequencing. This provided a criterion to select a restricted panel of five capturing antibodies and to test each of them against the rest of the 96 clones. The method constitutes a powerful tool for epitope binning, and in our case allowed development of a sandwich ELISA for sEH with a detection limit of 63 pg/mL and four log dynamic range, which performed with excellent recovery in different tissue extracts. This strategy provides a systematic way to test nanobody pairwise combinations and would have a broad utility for the development of highly sensitive sandwich immunoassays.
ABSTRACT The harmful bloom-forming cyanobacterium Cylindrospermopsis raciborskii grows in freshwa... more ABSTRACT The harmful bloom-forming cyanobacterium Cylindrospermopsis raciborskii grows in freshwaters over a wide range of light conditions. This species has increased its global distribution recently. The influence of ultraviolet radiation (UVR) on the fitness and toxin production of C. raciborskii has not previously been explored. We performed short-term experiments with three C. raciborskii strains (MVCC19, LB2897 and CYP011K), and we compared their responses with other bloom-forming species (Microcystis sp.1 and Plankthotrix agardhii) to determine the impact of UV-B radiation on pigments, biomass and morphological traits. In addition, we analyzed the effect of UV-B on the saxitoxin content and sxtU gene expression in the strain MVCC19. C. raciborskii strains were stressed differentially by UV-B exposure as evidenced by changes in growth, morphology and heterocytes number. A significant increase in saxitoxin concentration and sxtU gene expression under UV-B, suggests that toxin production in C. raciborskii can be a response to UV-B stress. In comparison, Microcystis sp.1 was more tolerant while P. agardhii was severely impacted by UV-B, indicating also different sensitivities among cyanobacteria to UVR. Our results underscore the influence of UVR on C. raciborskii and the differences between strains which showed phenotypic plasticity, which potentially could affect its distribution in freshwaters.
We studied the accumulation and depuration of microcystin-LR (MCLR) in the hepatopancreas of the ... more We studied the accumulation and depuration of microcystin-LR (MCLR) in the hepatopancreas of the crab Neohelice granulata fed twice weekly with either non toxic or MCLR-producing Microcystis aeruginosa (strain NPDC1 or NPJB, respectively) during seven weeks. We also analyzed MCLR effects on the oxidative stress-and detoxification-related variables, superoxide dismutase and glutathione-S-transferase activities, and the levels of reduced glutathione and lipid peroxidation (as thiobarbituric acid reactive substances, TBARS). Hepatopancreas MCLR content slightly increased during the first three weeks, up to 8.8171.84 ng g À 1 wet tissue mass (WTM) and then started to decrease to a minimum of 1.5770.74 ng g À 1 WTM at the seventh week (po0.05 with respect to that in the first week). TBARS levels were about 55% higher in treated than in control N. granulata (po0.001 and po0.05) during the first three weeks of the experimental period. GSH content became 50% lower than in control individuals (po0.01) during weeks 6 and 7. SOD activity was increased by about 2-fold (po0.05 or po0.001) from week 3 to 7 in treated crabs with respect to control ones, while GST activity was about 70% higher in treated than in control crabs from week 4 to week 7 (po0.05). Our data suggest that in the hepatopancreas of N. granulata MCLR accumulation and oxidative damage are limited and reversed by detoxification-excretion and antioxidant mechanisms. The activation of these defensive mechanisms becomes evident at 3-4 weeks after the start of the intoxication.
C.M.,Cellular transport of microcystin-LR in rainbow trout (Oncorhynchus mykiss) across the intes... more C.M.,Cellular transport of microcystin-LR in rainbow trout (Oncorhynchus mykiss) across the intestinal wall: possible involvement of multidrug resistance-associated proteins, Aquatic Toxicology (2014),
Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) are persistent, toxic, and bioa... more Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) are persistent, toxic, and bioaccumulate in the environment. Due to their high analytical costs, these compounds are hardly regulated and mostly not monitored in the Third World. To overcome this, bioassays have been proposed as low-cost alternative methods. Two of the most established bioanalytical tools, the dioxin antibody-based enzyme-linked immunosorbent assay ELISA and the micro-EROD bioassay are evaluated and compared to high resolution gas chromatography and high resolution mass spectrometry (HRGC/HRMS) analytical methodology. The methods were tested using thirteen soils and sediment samples selected from diverse sites in Montevideo, Uruguay. The WHO 2005 total toxic equivalent (WHO 2005-TEQ) of soils ranged from 2.4 to 2212 (ng WHO 2005-TEQ/kg dry sample) and from 0.14 to 9.4 (ng WHO 2005-TEQ/kg dry sample) in sediments. This study shows significant contamination related to dioxin-like compounds, particularly in sites where uncontrolled burnings were carried out. ELISA and micro-EROD bioassay correlated well with HRGC/HRMS, R Spearman 0.773 and 0.913, respectively and were highly correlated to each other, R Spearman 0.879. Preliminary threshold values of bioassay toxic equivalents of 330 (ng/kg dry sample) for the micro-EROD bioassay and 220 (ng/kg dry sample) for ELISA are proposed.
In recent years, the international demand for commodities has prompted enormous growth in agricul... more In recent years, the international demand for commodities has prompted enormous growth in agriculture in most South American countries. Due to intensive use of fertilizers, cyanobacterial blooms have become a recurrent phenomenon throughout the continent, but their potential health risk remains largely unknown due to the lack of analytical capacity. In this paper we report the main results and conclusions of more than five years of systematic monitoring of cyanobacterial blooms in 20 beaches of Montevideo, Uruguay, on the Rio de la Plata, the fifth largest basin in the world. A locally developed microcystin ELISA was used to establish a sustainable monitoring program that revealed seasonal peaks of extremely high toxicity, more than one-thousand-fold greater than the WHO limit for recreational water. Comparison with cyanobacterial cell counts and chlorophyll-a determination, two commonly used parameters for indirect estimation of toxicity, showed that such indicators can be highly misleading. On the other hand, the accumulated experience led to the definition of a simple criterion for visual classification of blooms, that can be used by trained lifeguards and technicians to take rapid on-site decisions on beach management. The simple and low cost approach is broadly applicable to risk assessment and risk management in developing countries.
We investigated the accumulation and toxicity of microcystin-LR (MCLR) in the digestive gland of ... more We investigated the accumulation and toxicity of microcystin-LR (MCLR) in the digestive gland of the freshwater clam Diplodon chilensis patagonicus. Treated clams were fed with a toxic strain of Microcystis aeruginosa (NPJB1) during 6 weeks and control clams received the non-toxic strain NPDC1. Filtration rate was estimated for both groups. Toxic effects were evaluated through the hepatosomatic index (HSI) and different oxidative stress biomarkers, lipid peroxidation (content of thiobarbituric reactive substances-TBARS), protein oxidation (carbonyl groups) and reduced glutathione (GSH) levels, and enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST). The extractable MCLR measured by ELISA in digestive gland extracts showed little or no change during the first 3 weeks and increased significantly at weeks 5 and 6. HSI was reduced by 30% in treated clams at weeks 5 and 6. No significant oxidative damage to lipids or proteins was. All the antioxidant defense parameters analyzed were significantly increased at week 5 or 6. GSH increased in treated clams at week 5, reaching 62% increase at week 6. SOD, CAT and GST activities were significantly increased in treated clams by 50%, 66% and 60%, respectively, at the end of the experiment. D. chilensis patagonicus can be exposed to prolonged cyanobacterial blooms accumulating significant quantities of MCLR, which could be a risk for mammals and birds, which feed on this species and, in a lesser extent, to humans.
New methodology in the determination of microcystins in fish. Study of Astraloheros facetus expos... more New methodology in the determination of microcystins in fish. Study of Astraloheros facetus exposed in vitro Novas metodologias para a análise de microcistinas em peixes. Estudo de Astraloheros facetus expostos in vitro
Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associa... more Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associated with eutrophication (nutrient enrichment) and changes in hydrology. In this study we analysed the distribution of planktonic cyanobacteria in Uruguay and their toxins (microcystin, saxitoxin and cylindrospermopsin), working with an interagency team (OSE, DINAMA, IM, University of the Republic and IIBCE). An historical data base (n = 3061 for 64 ecosystems, years 1980-2014) was generated. Differences between lotic and lentic ecosystems were found in terms of chlorophyll a and nutrient concentrations, usually indicating eutrophication. Two geo-referenced maps for the country were generated with cyanobacteria biomass indicators and the most relevant toxin (microcystin), according to risk levels suggested by the World Health Organization for recreational waters. The areas of greatest risk of exposure were the reservoirs of large rivers (Uruguay and Río Negro) and Río de la Plata beaches....
KruK, Carla (1,2); Martínez, ana (3); Martínez de la esCalera, Gabriela (4); trinChin, roMina (5)... more KruK, Carla (1,2); Martínez, ana (3); Martínez de la esCalera, Gabriela (4); trinChin, roMina (5); Manta, Gastón (5); seGura, anGel M. (6); PiCCini, Claudia (4); brena, beatriz (7); Fabiano, GraCiela (3,8); Pirez, MaCarena (9); Gabito, lourdes (2); alCántara, iGnaCio (2); YanniCelli, beatriz (2) (1) instituto de eColoGía Y CienCias aMbientales, FaCultad de CienCias, udelar, Montevideo, uruGuaY (2) eColoGía FunCional de sisteMas aCuátiCos, Centro universitario reGional del este (Cure), udelar, roCha, uruGuaY. (3) direCCión naCional de reCursos aCuátiCos, la PaloMa, MGaP, roCha, uruGuaY. (4) dePartaMento de MiCrobioloGía, instituto de investiGaCiones biolóGiCas CleMente estable, MeC, Montevideo, uruGuaY,
Bulletin of Environmental Contamination and Toxicology, 2018
We analyzed the effects of stratification changes due to wind on the vertical cyanobacteria distr... more We analyzed the effects of stratification changes due to wind on the vertical cyanobacteria distribution and microcystin-LR concentrations in a reservoir and assessed the implications for water management. Under stratified conditions, the highest microcystin concentrations (up to 4.16 µg/L) and toxic cyanobacteria biovolume occurred in the epilimnion (~ 1 m). The lowest microcystin concentrations were between 0.02 and 1.28 µg/L and occurred in the hypolimnion (~ 20 m). A cold front passage associated with high wind velocities induced water column mixing, promoting the redistribution of microcystin-LR and cyanobacteria throughout the water column and increasing their concentrations in deeper zones. Microcystin-LR concentration was positively correlated with cyanobacteria biovolume (r = 0.747) and chlorophyll a concentration (r = 0.798). Changes in thermal profile due to wind would imply a greater challenge for drinking water treatment plants, since high cyanobacterial and microcystin concentrations could reach deep-water intakes. Keywords Stratification • Microcystin • Cyanobacteria • Reservoir • Bonete Thermal stratification is a physical mechanism that can affect water quality in lakes and reservoirs. Most of the
Blooms of Nostocales (Cyanobacteria) are thought to be invading subtropical and temperate water b... more Blooms of Nostocales (Cyanobacteria) are thought to be invading subtropical and temperate water bodies. According to nutrient stoichiometry and physiological differences between cyanobacterial groups, the replacement of non-heterocystous species by Nostocales is favored when dissolved inorganic nitrogen decreases. However, some studies have shown different trends. We used laboratory bioassays to evaluate the concomitant effects of light and nutrient enrichment on phytoplankton assemblages dominated by non-heterocystous filamentous cyanobacteria. Three nutrient conditions (no addition, addition of phosphate, and addition of nitrate and phosphate) and two light intensities (40 and 80 lmol photon m-2 s-1) were assayed. Nostocales replaced or co-dominated with non-heterocystous species in all treatments by the end of the study. The shift in community composition towards Nostocales dominance led to an increase in species richness, which suggests that species with different eco-physiological traits may have differential impacts on diversity. The highest saxitoxin concentrations were measured in no addition treatments, which could link production to nutritional stress. Nostocales featured high phenotypic plasticity in terms of changes in average trichome Handling editor: Boping Han
Single domain heavychain binders (nanobodies) obtained from camelid antibody libraries hold a gre... more Single domain heavychain binders (nanobodies) obtained from camelid antibody libraries hold a great promise for immunoassay development. However, there is no simple method to select the most valuable nanobodies from the crowd of positive clones obtained after the initial screening. In this paper, we describe a novel nanobody-based platform that allows comparison of the reactivity of hundreds of clones with the labeled antigen, and identifies the best nanobody pairs for twosite immunoassay development. The output clones are biotinylated in vivo in 96-well culture blocks and then used to saturate the biotin binding capacity of avidin coated wells. This standardizes the amount of captured antibody allowing their sorting by ranking their reactivity with the labeled antigen. Using human soluble epoxide hydrolase (sEH) as a model antigen, we were able to classify 96 clones in four families and confirm this classification by sequencing. This provided a criterion to select a restricted panel of five capturing antibodies and to test each of them against the rest of the 96 clones. The method constitutes a powerful tool for epitope binning, and in our case allowed development of a sandwich ELISA for sEH with a detection limit of 63 pg/mL and four log dynamic range, which performed with excellent recovery in different tissue extracts. This strategy provides a systematic way to test nanobody pairwise combinations and would have a broad utility for the development of highly sensitive sandwich immunoassays.
ABSTRACT The harmful bloom-forming cyanobacterium Cylindrospermopsis raciborskii grows in freshwa... more ABSTRACT The harmful bloom-forming cyanobacterium Cylindrospermopsis raciborskii grows in freshwaters over a wide range of light conditions. This species has increased its global distribution recently. The influence of ultraviolet radiation (UVR) on the fitness and toxin production of C. raciborskii has not previously been explored. We performed short-term experiments with three C. raciborskii strains (MVCC19, LB2897 and CYP011K), and we compared their responses with other bloom-forming species (Microcystis sp.1 and Plankthotrix agardhii) to determine the impact of UV-B radiation on pigments, biomass and morphological traits. In addition, we analyzed the effect of UV-B on the saxitoxin content and sxtU gene expression in the strain MVCC19. C. raciborskii strains were stressed differentially by UV-B exposure as evidenced by changes in growth, morphology and heterocytes number. A significant increase in saxitoxin concentration and sxtU gene expression under UV-B, suggests that toxin production in C. raciborskii can be a response to UV-B stress. In comparison, Microcystis sp.1 was more tolerant while P. agardhii was severely impacted by UV-B, indicating also different sensitivities among cyanobacteria to UVR. Our results underscore the influence of UVR on C. raciborskii and the differences between strains which showed phenotypic plasticity, which potentially could affect its distribution in freshwaters.
We studied the accumulation and depuration of microcystin-LR (MCLR) in the hepatopancreas of the ... more We studied the accumulation and depuration of microcystin-LR (MCLR) in the hepatopancreas of the crab Neohelice granulata fed twice weekly with either non toxic or MCLR-producing Microcystis aeruginosa (strain NPDC1 or NPJB, respectively) during seven weeks. We also analyzed MCLR effects on the oxidative stress-and detoxification-related variables, superoxide dismutase and glutathione-S-transferase activities, and the levels of reduced glutathione and lipid peroxidation (as thiobarbituric acid reactive substances, TBARS). Hepatopancreas MCLR content slightly increased during the first three weeks, up to 8.8171.84 ng g À 1 wet tissue mass (WTM) and then started to decrease to a minimum of 1.5770.74 ng g À 1 WTM at the seventh week (po0.05 with respect to that in the first week). TBARS levels were about 55% higher in treated than in control N. granulata (po0.001 and po0.05) during the first three weeks of the experimental period. GSH content became 50% lower than in control individuals (po0.01) during weeks 6 and 7. SOD activity was increased by about 2-fold (po0.05 or po0.001) from week 3 to 7 in treated crabs with respect to control ones, while GST activity was about 70% higher in treated than in control crabs from week 4 to week 7 (po0.05). Our data suggest that in the hepatopancreas of N. granulata MCLR accumulation and oxidative damage are limited and reversed by detoxification-excretion and antioxidant mechanisms. The activation of these defensive mechanisms becomes evident at 3-4 weeks after the start of the intoxication.
C.M.,Cellular transport of microcystin-LR in rainbow trout (Oncorhynchus mykiss) across the intes... more C.M.,Cellular transport of microcystin-LR in rainbow trout (Oncorhynchus mykiss) across the intestinal wall: possible involvement of multidrug resistance-associated proteins, Aquatic Toxicology (2014),
Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) are persistent, toxic, and bioa... more Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) are persistent, toxic, and bioaccumulate in the environment. Due to their high analytical costs, these compounds are hardly regulated and mostly not monitored in the Third World. To overcome this, bioassays have been proposed as low-cost alternative methods. Two of the most established bioanalytical tools, the dioxin antibody-based enzyme-linked immunosorbent assay ELISA and the micro-EROD bioassay are evaluated and compared to high resolution gas chromatography and high resolution mass spectrometry (HRGC/HRMS) analytical methodology. The methods were tested using thirteen soils and sediment samples selected from diverse sites in Montevideo, Uruguay. The WHO 2005 total toxic equivalent (WHO 2005-TEQ) of soils ranged from 2.4 to 2212 (ng WHO 2005-TEQ/kg dry sample) and from 0.14 to 9.4 (ng WHO 2005-TEQ/kg dry sample) in sediments. This study shows significant contamination related to dioxin-like compounds, particularly in sites where uncontrolled burnings were carried out. ELISA and micro-EROD bioassay correlated well with HRGC/HRMS, R Spearman 0.773 and 0.913, respectively and were highly correlated to each other, R Spearman 0.879. Preliminary threshold values of bioassay toxic equivalents of 330 (ng/kg dry sample) for the micro-EROD bioassay and 220 (ng/kg dry sample) for ELISA are proposed.
In recent years, the international demand for commodities has prompted enormous growth in agricul... more In recent years, the international demand for commodities has prompted enormous growth in agriculture in most South American countries. Due to intensive use of fertilizers, cyanobacterial blooms have become a recurrent phenomenon throughout the continent, but their potential health risk remains largely unknown due to the lack of analytical capacity. In this paper we report the main results and conclusions of more than five years of systematic monitoring of cyanobacterial blooms in 20 beaches of Montevideo, Uruguay, on the Rio de la Plata, the fifth largest basin in the world. A locally developed microcystin ELISA was used to establish a sustainable monitoring program that revealed seasonal peaks of extremely high toxicity, more than one-thousand-fold greater than the WHO limit for recreational water. Comparison with cyanobacterial cell counts and chlorophyll-a determination, two commonly used parameters for indirect estimation of toxicity, showed that such indicators can be highly misleading. On the other hand, the accumulated experience led to the definition of a simple criterion for visual classification of blooms, that can be used by trained lifeguards and technicians to take rapid on-site decisions on beach management. The simple and low cost approach is broadly applicable to risk assessment and risk management in developing countries.
We investigated the accumulation and toxicity of microcystin-LR (MCLR) in the digestive gland of ... more We investigated the accumulation and toxicity of microcystin-LR (MCLR) in the digestive gland of the freshwater clam Diplodon chilensis patagonicus. Treated clams were fed with a toxic strain of Microcystis aeruginosa (NPJB1) during 6 weeks and control clams received the non-toxic strain NPDC1. Filtration rate was estimated for both groups. Toxic effects were evaluated through the hepatosomatic index (HSI) and different oxidative stress biomarkers, lipid peroxidation (content of thiobarbituric reactive substances-TBARS), protein oxidation (carbonyl groups) and reduced glutathione (GSH) levels, and enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST). The extractable MCLR measured by ELISA in digestive gland extracts showed little or no change during the first 3 weeks and increased significantly at weeks 5 and 6. HSI was reduced by 30% in treated clams at weeks 5 and 6. No significant oxidative damage to lipids or proteins was. All the antioxidant defense parameters analyzed were significantly increased at week 5 or 6. GSH increased in treated clams at week 5, reaching 62% increase at week 6. SOD, CAT and GST activities were significantly increased in treated clams by 50%, 66% and 60%, respectively, at the end of the experiment. D. chilensis patagonicus can be exposed to prolonged cyanobacterial blooms accumulating significant quantities of MCLR, which could be a risk for mammals and birds, which feed on this species and, in a lesser extent, to humans.
New methodology in the determination of microcystins in fish. Study of Astraloheros facetus expos... more New methodology in the determination of microcystins in fish. Study of Astraloheros facetus exposed in vitro Novas metodologias para a análise de microcistinas em peixes. Estudo de Astraloheros facetus expostos in vitro
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