Universidade
Federal do Rio Grande

Navegando por Autor "Monserrat, José María"

Agora exibindo 1 - 20 de 119

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Acetylcholinesterase activity and antioxidant capacity of zebrafish brain is altered by heavy metal exposure
(2011) Richetti, Stefânia Konrad; Rosemberg, Denis Broock; Ventura-Lima, Juliane; Monserrat, José María; Bogo, Maurício Reis; Bonan, Carla Denise
Pollution is a world problem with immeasurable consequences. Heavy metal compounds are frequently found as components of anthropogenic pollution. Here we evaluated the effects of the treatment with cadmium acetate, lead acetate, mercury chloride, and zinc chloride in acetylcholinesterase activity and gene expression pattern, as well as the effects of these treatments in antioxidant competence in the brain of an aquatic and well-established organism for toxicological analysis, zebrafish (Danio rerio,Cyprinidae). Mercury chloride and lead acetate promoted a significant decrease in acetylcholinesterase activitywhereas they did not alter the gene expression pattern. In addition, the antioxidant competence was decreased after exposure to mercury chloride. The data presented here allowed us to hypothesize a signal transmission impairment, through alterations in cholinergic transmission, and also in the antioxidant competence of zebrafish brain tissue as some of the several effects elicited by these pollutants.
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Analysis of laboratory intercomparison data: a matter of independence
(2003) Rebelo, Mauro Freitas; Monserrat, José María; Bastos, Wanderley Rodrigues
When laboratory intercomparison exercises are conducted, there is no a priori dependence of the concentration of a certain compound determined in one laboratory to that determined by another(s). The same applies when comparing different methodologies. A existing data set of total mercury readings in fish muscle samples involved in a Brazilian intercomparison exercise was used to show that correlation analysis is the most effective statistical tool in this kind of experiments. Problems associated with alternative analytical tools such as mean or paired ‘t’-test comparison and regression analysis are discussed.
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Annelids and Nematodes as Sentinels of Environmental Pollution
(2003) Monserrat, José María; Rosa, Carlos Eduardo da; Sandrini, Juliana Zomer; Marins, Luis Fernando Fernandes; Bianchini, Adalto; Monserrat, Laura Alicia Geracitano
Worms like polychaetes, oligochaetes, and nematodes, have been widely used in studies of aquatic and soil pollution. Several ecotoxicological characteristics make these animals suitable for use as a biomonitor, including the fact that these organisms live in close contact with sediments. Also important is that they posses little mobility, which could be useful in biomonitoring programs since it can reflect local environmental problems. Several toxicological aspects are reviewed in these zoological groups, including their antioxidant responses and detoxifying mechanisms of heavy metals. Interestingly, the nematodes and oligochaetes species show induction of proteins different from the well-known metallothionein, including cysteine-rich proteins, and phytochelatins, this last group until recently believed to be present only in plants and fungi.
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Anticholinesterase effect of eserine (physostigmine) in fish and crustacean species
(2001) Monserrat, José María; Bianchini, Adalto
The kinetic characteristic (Km) of cholinesterase from the crab Chasmagnathus granulata, the shrimp Farfantepenaeus paulensis and the fish Odontesthes bonaeriensis were compared and correlated with the anticholinesterasic effect of eserine (physostigmine). For the crustaceans, the estimated Km values were about 5-8 times higher than that estimated for the fish (0.04 mM). In the crab and the shrimp, the concentration of eserine which inhibited 50% of cholinesterase activity (IC50) was estimated as 5.33x10-4 and 4.33x10-4 mM, respectively. In both cases, it was significantly higher (P < 0.05) than that estimated for the fish larvae (7.43x10-5 mM). A high Km could reflect a lower affinity of the cholinesterase for its natural substrate, acetylcholine, or for substrate analogues such as carbamates and organophosphorous pesticides. If we consider the IC50 for eserine as an index of enzyme susceptibility to pesticide inhibition, the cholinesterase from the fish larvae may be a better useful tool in assays for pesticide biomonitoring than that from crustacean species.
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Antioxidant mechanisms of the nereidid (anelida: polychaeta) to cope with environmental hydrogen peroxide
(2005) Rosa, Carlos Eduardo da; Iurman, Mariana G.; Abreu, Paulo Cesar Oliveira Vergne de; Monserrat, Laura Alicia Geracitano; Monserrat, José María
Hydrogen peroxide (H2O2) is a naturally occurring prooxidant molecule, and its effects in the macroinvertebrate infauna were previously observed. The existence of a gradient of antioxidant enzymes activity (catalase [CAT], glutathione peroxidase [GPx], suéroxide dismutase [SOD], and glutathione-S-transferase [GST] and/or oxidative demage along the body of the estuarine polychaeta Laeonereis acuta (Polychaeta, Nereididae) was analyzed after exposure to H2O2. Because this species secretes conspicuous amounts of mucus, its capability in degrading H2O2 was studied. The results suggest that L. acuta deal with the generation of oxidative stress with different strategies along the body. In the posterior region, higher CAT and SOD activities ensure the degradation of inductors of lipid peroxidation such as H2O2 and superoxide anion (O2.-). The higher GST activity in anterior region aids to conjugate lipid peroxides products. In the middle region, the lack of high CAT, SOD, or GST activities correlates with the higher lipid hydroperoxide levels found after H2O2 exposure. Ten days of exposure to H2O2 also induced oxidative stress (lipid peroxidation and DNA damage) in the whole animal paralleled by a lack of CAT induction. The mucus production contributes substantially to H2O2 degradation, suggesting that bacteria that grow in this secretion provide this capabiblity.
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Antioxidant properties of the mucus secreted by Laeonereis acuta (Polychaeta, Nereididae): a defense against environmental pro-oxidants?
(2006) Moraes, Tarsila Barros; Ferreira, Josencler Luis Ribas; Rosa, Carlos Eduardo da; Sandrini, Juliana Zomer; Votto, Ana Paula de Souza; Trindade, Gilma Santos; Monserrat, Laura Alicia Geracitano; Abreu, Paulo Cesar Oliveira Vergne de; Monserrat, José María
Polychaeta species like Laeonereis acuta (Nereididae) usually secrete great amounts of mucus that wrap the animal inside. Taking into account that fungi action in the sediment and UV radiation acting on dissolved organic matter in the water produces reactive oxygen species (ROS) like hydrogen peroxide (H2O2), it was considered that the mucus secretion could represent an antioxidant defense against environmental ROS. Antioxidant enzymes (catalase—CAT; superoxide dismutase—SOD; glutathione peroxidase—GPx and glutathione-S-transferase—GST) and total antioxidant capacity (TOSC) were determined in worms and mucus secretion. Higher (pb0.05) CAT, GPx and TOSC values were registered in mucus samples respect worms, SOD activity was similar (pN0.05) in both kind of samples, and absence of GST activity was observed in mucus samples, suggesting absence of catalyzed phase II reactions. In assays conducted with hepatoma cell lines exposed to H2O2, it was verified that:(1) mucus co-exposure significantly (pb0.05) lowered DNA damage induced by H2O2; (2) ROS production was significantly (pb0.05) reduced when cells were exposed simultaneously with mucus samples and H2O2 respect H2O2 alone. It can be concluded that the mucus production contributes substantially to the antioxidant defense system of the worm against environmental ROS through the interception or degradation of H2O2, peroxyl and hydroxyl radicals.
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Antioxidant responses after microcystin exposure in gills of an estuarine crab species pre-treated with vitamin E
(2005) Pinho, Grasiela Lopes Leães; Rosa, Cristiane Moura da; Maciel, Fabio Everton; Bianchini, Adalto; Yunes, João Sarkis; Proença, Luis Antonio de Oliveira; Monserrat, José María
Microcystins are hepatotoxins suspected to generate oxidative stress. This mechanism was evaluated in gills of the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura). Adult male crabswere fed ground beef with or without vitamin E (600 mg/kg). Microcystin (1.21 mg/kg) was daily administered through forced ingestion, for 7 days. After exposure, catalase activity was reduced in posterior gills of crabs supplemented with vitamin E. A lower increment in glutathione S-transferase activity (GST) was observed in organisms pretreated with vitamin E and then exposed to microcystin with respect to those exposed to the toxin but not pretreated with the vitamin. Pretreatment with vitamin E also increased nonproteic sulfhyrdil groups and this effect was not observed after microcystin exposure. The fact that supplementation with antioxidants such as vitamin E modulates GST activity indicates the direct or indirect involvement of microcystin in oxidative stress generation.
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Antioxidant responses and oxidative stress after microcystin exposure in the hepatopancreas of an estuarine crab species
(2005) Pinho, Grasiela Lopes Leães; Rosa, Cristiane Moura da; Maciel, Fabio Everton; Bianchini, Adalto; Yunes, João Sarkis; Proença, Luis Antonio de Oliveira; Monserrat, José María
Antioxidant responses and oxidative stress were evaluated in the hepatopancreas of the estuarine crab Chasmagnathus granulates (Decapoda, Brachyura) after oral microcystin administration. Responses were evaluated through antioxidant enzyme activities (catalase-(CAT), superoxide dismutase, glutathione-S-transferase- (GST)). Nonproteic sulfhydril (NP-SH) groups, oxygen consumption, lipid peroxides (LPO), and oxidized proteins were also measured. Microcystin administration increased the oxygen consumption. GST activity and NP-SH concentration showed transient increases and CAT activity showed a peak and then a reduction. Oxidative damage was evidenced with regard to LPO content and suggested by the inhibition of CAT activity at the end of the experiment, indicating that the antioxidant response induced by the toxin was insufficient. A lowering in the number of hepatopancreatic B cells should be related to microcystin elimination.
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Antioxidant responses and reactive oxygen species generation in different body regions of the estuarine polychaeta Laeonereis acuta (Nereididae)
(2007) Cravo, Marlize Ferreira; Piedras, Fernanda Reinhardt; Moraes, Tarsila Barros; Ferreira, Josencler Luis Ribas; Freitas, Diana Paula Salomão de; Machado, Márcia Dornelles; Monserrat, Laura Alicia Geracitano; Monserrat, José María
The aim of this study was to analyze the total antioxidant capacity (TOSC), generation of reactive oxygen species (ROS) and lipid peroxidation (LPO) in the different body regions of the estuarine polychaeta Laeonereis acuta (Nereididae) sampled at non-polluted (NOPOL)and polluted (POL) sites from Lagoa dos Patos (Southern Brazil). Organisms collected at POL during summer showed similar (p > 0.05)TOSC values along the body, but worms collected at NOPOL presented higher (p < 0.05) TOSC values in the posterior (P) region in respect of anterior (A) region and middle (M) region. TOSC in the P region at NOPOL was higher (p < 0.05) compared with the same body region of worms at POL. In summer, ROS concentration was higher in A andMregions of worms at POL in respect of the organisms at NOPOL. During winter all the regions showed higher ROS in worms sampled at POL. It was registered absence of season influence on LPO content,but in the P region at NOPOL in summer there were lower LPO levels compared with the others regions (p < 0.05). In vitro assays showed that P region, despite a higher basal ROS, presented a higher competence to cope with pro-oxidants compared with A and M regions (p < 0.05), corroborating the field results. A lower proteic sulfhydril content was observed in P in respect of the other regions (p < 0.05) supporting the idea of a highest oxidant condition in this region. The results indicate that worms collected at the POL site are confronted to higher ROS concentrations, affecting its antioxidant capacity, a result that depends of body regions.
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Antioxidant responses in different body regions of the polychaeta Laeonereis acuta (Nereididae) exposed to copper
(2009) Cravo, Marlize Ferreira; Ventura-Lima, Juliane; Sandrini, Juliana Zomer; Amado, Lílian Lund; Monserrat, Laura Alicia Geracitano; Rebelo, Mauro; Bianchini, Adalto; Monserrat, José María
Antioxidant enzymes, total antioxidant capacity (TOSC) and concentration of reactive oxygen species (ROS) were measured in anterior (A), middle (M) and posterior (P) body regions of Laeonereis acuta after copper (Cu; 62.5 mg/l) exposure. A catalase (CAT) activity gradient observed in control group (lowest in A, highest in P) was not observed in Cu exposed group. Glutathione-S-transferase (GST) activity in A region of Cu group was higher than in A region of the control group. DNA damage (comet assay) was augmented in the A region of Cu group. Since copper accumulation was similar in the different body regions, sensitivity to copper in A regions seems to be related to lowest CAT activity. In sum, copper exposure lowered TOSC, a result that at least in part can be related to lowering of antioxidant enzymes like CAT. DNA damage was induced in the anterior region, where a lower CAT activity was observed.
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Antioxidant responses in the nereidid Laeonereis acuta (Annelida, Polychaeta) after cadmium exposure
(2008) Sandrini, Juliana Zomer; Ventura-Lima, Juliane; Regoli, Francesco; Fattorini, Daniele; Notti, Alessandra; Marins, Luis Fernando Fernandes; Monserrat, José María
The objective of this study was to evaluate the effects of the exposure to cadmium on the antioxidant responses in the polychaeta Laeonereis acuta. The worms were submitted to 0, 5, and 100 mg of Cd/L during a period of test of 7 days. Cadmium was significantly (po0.05) accumulated in L. acuta in both concentrations assayed, but the concentration of reactive oxygen and nitrogen species (RONS)increased (po0.05) only in the group submitted to the highest concentration of cadmium (100 mg/L). At this concentration, a decrease in the activity of the superoxide dismutase and an increase of glutathione-S-transferase activity (po0.05) was observed. The levels of both lipid peroxides and the activities of catalase and glutathione peroxidase were not affected (p40.05) by the exposition to cadmium. Thus,cadmium can augment RONS levels and can interfere with the antioxidant defense system of the polychaete L. acuta, although cadmium does not directly induce oxidative stress unlike copper and iron.
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Antioxidant responses in the polychate Perinereis gualpensis (Nereididae) after exposure to the carbon nanomaterial fullerene (C60) in sediments
(2011) Jaramillo, Mauricio Diaz; Ferreira, Josencler Luis Ribas; Rocha, Alessandra Martins da; Bay-Smith, E.; Fillmann, Gilberto; Barra, Ricardo; Monserrat, José María
The objective of this study was to analyse biochemical responses induced by the carbon nanomaterial fullerene (C60) in the polychaete Perinereis gualpensis(Nereididae). The activity of glutathione-Stransferase (GST), glutathione reductase (GR) and glutamate cysteine ligase (GCL), as well as total antioxidant capacity, concentration of glutathione (GSH) and malondialdehyde (TBARS), were analysed. Estuarine worms were maintained in sediments collected at an unpolluted site and spiked with fullerene (3 mg C60·g−1 sediment).Acontrol groupwas run in parallel. Scanning electron microscope (SEM) images of sediment and fullerene indicated that the size of the carbon nanomaterial should enable it to be ingested by the polychaete. No evidence of oxidative damage (TBARS) was observed in any of the treatments, and the same was true for GSH and GCL measurements (p > 0.05). Total antioxidant capacity was higher in the C60 group after 2 and 7 d when compared with the control group (p < 0.05), suggesting that fullerene is acting as an antioxidant. The fact that P. gualpensis is an infaunal organism diminishes the chance of fullerene photoexcitation with consequent reactive oxygen species production. Thus, the data indicated an absence of toxic responses mediated by oxidative stress in estuarine worms exposed to C60 mixed in sediments.
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Antioxidant responses of Laeonereis acuta (Polychaeta) after exposure to hydrogen peroxide
(2008) Rosa, Carlos Eduardo da; Bianchini, Adalto; Monserrat, José María
The effects of H2O2 were evaluated in the estuarine worm Laeonereis acuta (Polychaeta, Nereididae) collected at the Patos Lagoon estuary (Southern Brazil) and maintained in the laboratory under controlled salinity (10 psu diluted seawater) and temperature (20°C). The worms were exposed to H2O2 (10 and 50 μM) for 4, 7, and 10 days and the following variables were determined: oxygen consumption, catalase (CAT) and glutathione peroxidase activity in both the supernatant and pellet fractions of whole body homogenates. The concentrations of non-protein sulfhydryl and lipid peroxides (LPO) were also measured. The oxygen consumption response was biphasic, decreasing after 4 days and increasing after 7 and 10 days of exposure to 50 μM H2O2 (P < 0.05). At the same H2O2 concentration, CAT activity was lower (P < 0.05) in the pellet fraction of worms exposed for 10 days compared to control. Non-protein sulfhydryl concentration and glutathione peroxidase activity were not affected by H2O2 exposure. After 10 days, LPO levels were higher (P < 0.05) in worms exposed to 50 μM H2O2 compared to control. The reduction in the antioxidant defense was paralleled by oxidative stress as indicated by higher LPO values (441% compared to control). The reduction of CAT activity in the pellet fraction may be related to protein oxidation. These results, taken together with previous findings, suggest that the worms were not able to cope with this H2O2 concentration.
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Antioxidant responses of Laeonereis acuta (Polychaeta) after exposure to hydrogen peroxide
(2008) Rosa, Carlos Eduardo da; Bianchini, Adalto; Monserrat, José María
The effects of H2O2 were evaluated in the estuarine worm Laeonereis acuta (Polychaeta, Nereididae) collected at the Patos Lagoon estuary (Southern Brazil) and maintained in the laboratory under controlled salinity (10 psu diluted seawater) and temperature (20°C). The worms were exposed to H2O2 (10 and 50 μM) for 4, 7, and 10 days and the following variables were determined: oxygen consumption, catalase (CAT) and glutathione peroxidase activity in both the supernatant and pellet fractions of whole body homogenates. The concentrations of non-protein sulfhydryl and lipid peroxides (LPO) were also measured. The oxygen consumption response was biphasic, decreasing after 4 days and increasing after 7 and 10 days of exposure to 50 μM H2O2 (P < 0.05). At the same H2O2 concentration, CAT activity was lower (P < 0.05) in the pellet fraction of worms exposed for 10 days compared to control. Non-protein sulfhydryl concentration and glutathione peroxidase activity were not affected by H2O2 exposure. After 10 days, LPO levels were higher (P < 0.05) in worms exposed to 50 μM H2O2 compared to control. The reduction in the antioxidant defense was paralleled by oxidative stress as indicated by higher LPO values (441% compared to control). The reduction of CAT activity in the pellet fraction may be related to protein oxidation. These results, taken together with previous findings, suggest that the worms were not able to cope with this H2O2 concentration.
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Antioxidant responses of laeonereis acuta (polychaeta) after exposure to hydrogen peroxide
(2008) Rosa, Carlos Eduardo da; Bianchini, Adalto; Monserrat, José María
The effects of H2O2 were evaluated in the estuarine worm Laeonereis acuta (Polychaeta, Nereididae) collected at the Patos Lagoon estuary (Southern Brazil) and maintained in the laboratory under controlled salinity (10 psu diluted seawater) and temperature (20°C). The worms were exposed to H2O2 (10 and 50 μM) for 4, 7, and 10 days and the following variables were determined: oxygen consumption, catalase (CAT) and glutathione peroxidase activity in both the supernatant and pellet fractions of whole body homogenates. The concentrations of non-protein sulfhydryl and lipid peroxides (LPO) were also measured. The oxygen consumption response was biphasic, decreasing after 4 days and increasing after 7 and 10 days of exposure to 50 μM H2O2 (P < 0.05). At the same H2O2 concentration, CAT activity was lower (P < 0.05) in the pellet fraction of worms exposed for 10 days compared to control. Non-protein sulfhydryl concentration and glutathione peroxidase activity were not affected by H2O2 exposure. After 10 days, LPO levels were higher (P < 0.05) in worms exposed to 50 μM H2O2 compared to control. The reduction in the antioxidant defense was paralleled by oxidative stress as indicated by higher LPO values (441% compared to control). The reduction of CAT activity in the pellet fraction may be related to protein oxidation. These results, taken together with previous findings, suggest that the worms were not able to cope with this H2O2 concentration.
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Application of public-domain statistical analysis software for evaluation and comparison of comet assay data
(2006) Verde, Pablo Emílio; Monserrat, Laura Alicia Geracitano; Amado, Lílian Lund; Rosa, Carlos Eduardo da; Bianchini, Adalto; Monserrat, José María
A novel approach for statistical analysis of comet assay data (i.e.: tail moment) is proposed, employing public-domain statistical software, the R system. The analytical strategy takes into account that the distribution of comet assay data, like the tail moment, is usually skewed and do not follow a normal distribution. Probability distributions used to model comet assay data included: the Weibull, the exponential, the logistic, the normal, the log normal and log-logistic distribution. In this approach it was also considered that heterogeneity observed among experimental units is a random feature of the comet assay data. This statistical model can be characterized with a location parameter mij, a scale parameter r and a between experimental units variability parameter θ. In the logarithmic scale, the parameter mij depends additively on treatment and random effects, as follows: log(mij) = a0 + a1xij + bi, where exp(a0) represents approximately the mean value of the control group, exp(a1) can be interpreted as the relative risk of damage with respect to the control group, xij is an indicator of experimental group and exp(bi) is the individual risk effects assume to follows a Gamma distribution with mean 1 and variance θ. Model selection is based on Akaike’s information criteria (AIC). Real data coming from comet analysis of blood samples taken from the flounder Paralichtys orbignyanus (Teleostei: Paralichtyidae) and from samples of cells suspension obtained from the estuarine polychaeta Laeonereis acuta (Nereididae) were employed. This statistical approach showed that the comet assay data should be analyzed under a modeling framework that take into account the important features of these measurements. Model selection and heterogeneity between experimental units play central points in the analysis of these data.
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Arsenic toxicity in mammals and aquatic animals: A comparative biochemical approach
(2011) Ventura-Lima, Juliane; Bogo, Maurício Reis; Monserrat, José María
Arsenic(As)is a wide spread pollutant in the world and its toxicity is related to its chemical form,with inorganic forms being considered more toxic than the organic form, and huge differences ineffects and processes ofmetabolism.This paper reviews the potential biochemical mechanisms of up take o farsenic by aquaporins,capacity for metabolism and cellular efflux of As. It is known that As can affect signaling pathways since it can activate proteins such as ERK2, p38 and JNK,as shown in mammals.Acomparison between phosphorylation sites of these proteins is presented in order to determine whether the same effect triggered by As in mammals might be observed in aquatic animals.The toxicity resulting from As exposure is considered to be linked to an imbalance between pro-oxidant and antioxidant homeostasis that results in oxidative stress.So,present review analyzes examples of oxidative stress generation by arsenic.Biotransformation of As is a process where firstly the arsenate is converted into arsenite and then transformed into mono-,di-, and trimethylated products. In the methylation process,the role of the omega isoform of glutathione-S-transferase(GST)is discussed. In addition, a phylogenetic tree was constructed for aquaporin proteins of different species, including aquatica nimals,taking into account their importance in trivalent arsenic uptake
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Atividade colinesterásica no monitoramento ambiental: importância da determinação de parâmetros cinéticos em peixes estuarinos
(2005) Tortelli, Vanessa Pereira; Colares, Elton Pinto; Monserrat, José María
Neste trabalho foram analisados os parâmetros cinéticos e a atividade colinesterásica de duas espécies de peixes estuarinos: a corvina Micropogonias furnieri (Teleostei, Scianidae) e o bagre Cathorops spixii (Teleostei, Ariidae), buscando avaliar o uso destas espécies como bioindicadores da presença de compostos anticolinesterásicos no meio aquático. Os exemplares de corvina e bagre, respectivamente, foram coletados nos estados do RS (Lagoa dos Patos) e PR (Baía de Paranaguá) no inverno (corvina) e verão (corvina e bagre) em dois pontos de coleta: um local controle e outro poluído. Os peixes foram anestesiados (bezocaína, 200 ppm) e os cérebros dissecados, homogeneizados e centrifugados. Foram estimados os parâmetros cinéticos (Vmax e Kmap), utilizando iodeto de acetiltiocolina como substrato, nas seguintes concentrações: 0,025; 0,05; 0,2; 0,8; 1,6; 3,2 e 9 mM. Nos estudos de inibição enzimática foi utilizado o carbamato eserina em concentrações de 0,3 a 10 mM e de 1x10-4 a 1 µM, a fim de determinar os parâmetros cinéticos de inibição e a concentração de eserina que inibia 50% da atividade colinesterásica (CI50), respectivamente. Os resultados mostraram pouca variação nos valores de Kmap nas duas espécies, porém diferenças significativas nos valores de CI50 foram observadas, indicando que a ChE do cérebro da corvina M. furnieri é resistente à inibição por eserina. Nos estudos de cinética de inibição da ChE do cérebro do bagre C. spixii, foram encontradas diferenças entre alguns parâmetros, quando foram comparados os peixes coletados no local controle com aqueles coletados no local poluído. Houve uma maior atividade colinesterásica de bagres coletados no local poluído (p<0,05), sendo que o mesmo resultado foi observado em exemplares de corvinas M. furnieri coletados durante o inverno no local poluído. Os resultados obtidos in vitro demonstram que a ChE de M. furnieri possui pouca sensibilidade à eserina. 5 Porém, o fato de ter sido registrada inibição colinesterásica nos organismos coletados durante o verão região poluída sugere a possibilidade de alterações significativas na capacidade de bio-oxidação de pesticidas nesta espécie, ou a possibilidade de inibição por outros contaminantes que também afetam a atividade colinesterásica, como por exemplo, metais. No caso de C. spixii, a determinação dos parâmetros cinéticos e de atividade colinesterásica sugere que pode estar ocorrendo alterações bioquímicas nos peixes previamente expostos a contaminantes no ambiente, provavelmente devido a respostas adaptativas ao ambiente impactado. Desta forma, o presente estudo indica a importância de estudos cinéticos prévios, quando se utiliza ou pretende utilizar, a atividade colinesterásica como bioindicador da presença de compostos anticolinesterásicos no ambiente em espécies aquáticas.
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Avaliação da co-exposição in vitro do arsênio e do nanomaterial orgânico fulereno C60 em hepatócitos de zebrafish Danio rerio
(2011) Costa, Carmen Luiza de Azevedo; Monserrat, José María
As nanopartículas são materiais que possuem pelo menos uma dimensão na faixa de 1 a 100 nm e devido a sua capacidade de interagir com outras moléculas, os nanomateriais apresentam muitas aplicações biotecnológicas. Mesmo com a crescente demanda e utilização de produtos oriundos do campo da nanotecnologia, pouco se sabe dos impactos causados por estes aos sistemas biológicos. Dentre as nanopartículas podemos citar o fulereno (C60), um composto orgânico lipofílico que, potencialmente, poderia servir como carreador de moléculas tóxicas. Tendo-se em vista o conceito de "cavalo de Tróia", onde contaminantes podem ter sua entrada em órgãos específicos potencializada por sua associação com nanopartículas, torna-se imprescindível conhecer as possíveis consequências biológicas desta associação. Hepatócitos de zebra fish, foram expostos ao arsênio, ao fulereno e em forma conjunta (As + C60) por 4 h, período em que a viabilidade celular não foi alterada. A produção de espécies reativas de oxigênio foi reduzida (p<0,05) no grupo controle e na concentração 100µM As co-expostas com C60; a concentração intracelular de GSH foi reduzida (p < 0.05) na concentração 2,5 µM As co-exposta com C60, sendo relacionado com a ausência de dano lipídico (TBARS) na mesma concentração. Não houve diferenças (p>0,05) no nível de proteínas oxidadas. A capacidade antioxidante total foi significativamente maior nas amostras de As coexpostas com C60, enquanto que a atividade da GST foi reduzida no tratamento As (100µM) + C60. Todos os resultados encontrados neste trabalho são fortemente sustentados pela comprovação do papel de carreadores das nanopartículas, pois a concentração intracelular de arsênio nas células co-expostas com fulereno apresentou um resultado significativamente maior. Portanto conclui-se que nestas concentrações, durante o tempo de exposição e com o modelo experimental utilizado o nanomaterial fulereno co-exposto com o arsênio apresenta capacidade antioxidante. Futuros estudos são necessários para avaliar a biodisponibilidade intracelular de arsênio depois de ser ligado ao nanomaterial fulereno.
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Avaliação da toxicidade de curativo impregnado com prata nanocristalina no verme Caenorhabditis elegans
(2019) Monteiro, Alinne Hoisler Ayech; Monserrat, José María
Uma crescente demanda na utilização de nanomateriais tem ocorrido nos últimos anos abrangendo produtos como cosméticos e fármacos. No entanto, as informações sobre a toxicidade dos produtos advindos das nanotecnologias ainda são limitadas. As nanopartículas de prata são utilizadas como bactericida e se fazem presentes em fármacos, materiais cirúrgicos, curativos, tecidos, entre outros. Dentre eles temos o 5Acticoat Flex 3, um curativo utilizado em ferimentos como queimaduras e, segundo o fabricante Smith e Nephew, é elaborado a base de prata nanocristalina. Após a utilização destes produtos, o descarte de maneira incorreta pode causar efeitos toxicológicos nos organismos presentes no ambiente. Visando avaliar a potencial periculosidade ambiental deste curativo, foi escolhido como organismo teste Caenorhabditis elegans, nematoide de vida livre que mede cerca de 1 mm. Nos ensaios foram utilizadas placas de 24 poços contendo 4 tamanhos diferentes de recortes do curativo, para obtenção de distintas concentrações onde animais em estágio larval L1 e L4 foram expostos. Estes recortes estiveram dispostos entre 2 camadas de ágar durante 3 dias e então a bactéria Escherichia coli (cepa OP50) foi adicionada como alimento para os vermes. Após o período de exposição, foram avaliados o crescimento, a reprodução, a fertilidade e a concentração de espécies reativas de oxigênio (ERO) no verme. No curativo foram realizadas análises de microscopia eletrônica de varredura e de transmissão, além de análises de prata liberada no meio, do potencial zeta, da liberação iônica e do poder antibacteriano em duas cepas bacterianas (Pseudomonas aeruginosa e Staphylococcus aureus). Foi verificado o poder antibacteriano do curativo para as duas cepas testadas, e a caracterização do curativo mostrou nanopartículas heterogêneas; Resultados como maior concentração de ERO, redução no crescimento, fertilidade e reprodução no verme indicam o potencial tóxico deste produto.