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1.
Ecotoxicol Environ Saf ; 205: 111337, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979804

RESUMO

Iron overload in water is a problem in many areas of the world, which could exert toxic effects on fish. To achieve maximum growth and overall fitness, iron induced toxicity must be alleviated. Therefore, this research was undertaken to investigate the potential mitigation of iron toxicity by dietary vitamin C supplementation in channel catfish (Ictalurus punctatus). Two doses of vitamin C (143 and 573 mg/kg diet) were tested against high environmental iron (HEI, 9.5 mg/L representing 25% of 96 h LC50). Fish were randomly divided into six groups with four replicated tanks. The groups were Control (vitamin C deficient feed), LVc (143 mg vitamin C supplemented per kg diet), HVc (573 mg vitamin C supplemented per kg diet), Con + Fe (control exposed to HEI), LVc + Fe (LVc exposed to HEI) and HVc + Fe (HVc exposed to HEI). Following an 8 week trial, there was a significant reduction in weight gain (WG%) in Con + Fe compared to the control, indicating a toxic effect of HEI on fish growth performance. Interestingly, WG% in both LVc + Fe and HVc + Fe groups were significantly higher than Cont + Fe, signifying that HEI inhibited growth, but this was alleviated by vitamin C. Both hemoglobin content and hematocrit were higher in LVc + Fe compared to the control and Con + Fe. In addition, exposure to HEI (Con + Fe) incited hepatic oxidative stress based on an over-accumulation of malondialdehyde (MDA) along with a significant inhibition in superoxide dismutase (SOD) and catalase (CAT) activities; whereas in LVc + Fe and HVc + Fe, the MDA content restored to basal level. A series of histopathological alterations were observed in the liver and gills, with the most severe lesions in Con + Fe, which was also complemented with a remarkable increase in hepatic iron accumulation. Vitamin C supplementations reduced the augmented concentrations of iron accumulation to that of the control. No effect, regardless of the treatments, was noted for fatty acid composition of muscle. Overall, our findings suggest that the vitamin C supplementation can be an effective therapeutic approach for boosting growth as well as alleviating iron toxicity in catfish.


Assuntos
Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Ictaluridae/metabolismo , Ferro/toxicidade , Poluentes Químicos da Água/toxicidade , Ração Animal , Animais , Antioxidantes/metabolismo , Dieta , Suplementos Nutricionais , Relação Dose-Resposta a Droga , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Ferro/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Distribuição Aleatória , Poluentes Químicos da Água/metabolismo
2.
Ecotoxicol Environ Saf ; 205: 111314, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32956866

RESUMO

Brazilian freshwater ecosystems are continuously exposed to pesticides and domestic sewage. The Uruguay River was chosen for this study because of its international importance, as it flows through Brazil, Argentina, and Uruguay. It receives contaminants such as pesticides and domestic residues. Thus, the aim of this study to assess the accumulation of pesticides in muscle of the fish Astyanax jacuhiensis, its biochemical responses, and the presence of pesticides in water. In total, seven pesticides were registered in water from both river sites. Eight pesticides were detected in fish muscle. The biochemical responses showed that brain lipid peroxidation (LPO) and protein carbonyl (PC) in A. jacuhiensis were higher in the summer. Muscle showed the highest LPO levels in the spring and the highest PC in the summer. Liver LPO and PC levels were higher in the spring and summer. In the gills, the PC was higher in the spring and the LPO in the spring and winter. In the brain and in the gills, glutathione-S-transferase activity was high in the summer and autumn. Catalase activity was lower during the winter and spring. Non-protein thiol (NPSH) levels were lower in the brain in the winter and spring. Muscle tissue showed lower NPSH in the winter (site 1). Liver NPSH showed increased levels in liver in the spring and winter (site 2). The biochemical results clearly is related to pesticides and/or to the presence of other contaminants in the water such as metals or domestic sewage. The accumulation of pesticides in fish muscle added evidence that pesticides have been used in the area surrounding the Uruguay River. In conclusion, the biomarkers assayed in the present study could be used in future investigations considering other sampling sites along Uruguay River.


Assuntos
Characidae/fisiologia , Monitoramento Ambiental , Praguicidas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Brasil , Characidae/metabolismo , Caraciformes/metabolismo , Caraciformes/fisiologia , Ecossistema , Brânquias/metabolismo , Peroxidação de Lipídeos , Metais/metabolismo , Praguicidas/análise , Rios/química , Estações do Ano , Poluentes Químicos da Água/análise
3.
Aquat Toxicol ; 226: 105567, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32745893

RESUMO

The increasing contamination of water bodies with mercury (Hg) raises concerns about the possible effects of this metal on native fish species. Our current understanding of its dynamics in fish organs remains limited. In this study, adult individuals of the native species Astyanax eigenmanniorum were exposed to three environmentally relevant HgCl2 concentrations (5, 100, and 170 µg L-1) for 96 h. To evaluate total Hg (THg) elimination, new individuals were exposed to 100 µg L-1 of HgCl2 (96 h), and at the end of the exposure period, half of the fish were placed in tanks with clean water for 168 h. In both assays, the organs were removed, and THg levels were measured using ICP-MS. The uptake of IHg in A. eigenmanniorum showed a differential accumulation in the organs. Gills, intestine, and brain were the tissues with the highest THg levels. Finally, no elimination of THg in the water was observed, but intestine and gills significantly removed the THg accumulated. Probably a Hg redistribution through the tissues could take place.


Assuntos
Characidae/metabolismo , Mercúrio/metabolismo , Poluentes Químicos da Água/metabolismo , Adulto , Animais , Bioacumulação , Encéfalo/metabolismo , Characidae/sangue , Monitoramento Ambiental , Brânquias/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Mercúrio/análise , Mercúrio/toxicidade , Taxa de Depuração Metabólica , Distribuição Tecidual , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
4.
Gene ; 763: 144956, 2020 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-32739586

RESUMO

Sox transcription factors play essential roles in a variety of critical physiological processes. Still, members of the sox gene family have not yet been genome-wide identified in shrimps. In this study, a total of five members of the sox gene family were identified from the genome of Pacific white shrimp Litopenaeus vannamei and classified into three subgroups based on the conserved HMG-box domain. Among them, three belong to the SoxB subgroup (one in B1 and two in B2), one in the SoxC subgroup, and one in the SoxE subgroup. The five sox genes had different sex-biased expression in some tissues. Sox21, soxB1, and sox14 had a higher expression in ovary than in testis. In comparison, sox4 had a male-biased specific expression in the gonad, hepatopancreas, gill, and eyestalk. There was no difference in soxE gene expression between testis and ovary. During embryonic development, the expression level of three sox genes (soxB1, sox21, and soxE) was higher in gastrulation stage compared to previous stages, declined in limb bud stage and then increased in intramembrane nauplius stage; the expression of sox4 was detected in blastula stage and continued to increase in the following two stages and then surged in intramembrane nauplius stage; the highest expression of sox14 was in the fertilized egg stage, and the expression level decreased with the development of the embryo. These results suggest that the shrimp sox gene family may be involved in gametogenesis, tridermogenesis, and neurogenesis.


Assuntos
Proteínas de Artrópodes/genética , Penaeidae/genética , Fatores de Transcrição SOX/genética , Animais , Proteínas de Artrópodes/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Brânquias/embriologia , Brânquias/metabolismo , Hepatopâncreas/embriologia , Hepatopâncreas/metabolismo , Masculino , Especificidade de Órgãos , Ovário/embriologia , Ovário/metabolismo , Penaeidae/embriologia , Fatores de Transcrição SOX/metabolismo , Testículo/embriologia , Testículo/metabolismo
5.
Chemosphere ; 258: 127408, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32782161

RESUMO

This study investigates the impacts of exposure to an environment Ca2+ challenge and the mechanism of action of dibutyl phthalate (DBP) on Ca2+ influx in the gills of Danio rerio. In vitro profile of 45Ca2+ influx in gills was verified through the basal time-course. Fish were exposed to low, normal and high Ca2+ concentrations (0.02, 0.7 and 2 mM) for 12 h. So, gills were morphologically analysed and ex vivo45Ca2+ influx at 30 and 60 min was determined. For the in vitro studies, gills were treated for 60 min with DBP (1 pM, 1 nM and 1 µM) with/without blockers/activators of ionic channels, Ca2+ chelator, inhibitors of ATPases, ionic exchangers and protein kinase C to study the mechanism of DBP-induced 45Ca2+ influx. Exposure to high environmental Ca2+ augmented 45Ca2+ influx when compared to fish exposed to normal and low Ca2+ concentrations. Additionally, histopathological changes were observed in the gills of fish maintained for 12 h in low and high Ca2+. In vitro exposure of gills to DBP (1 pM) disturbed Ca2+ homeostasis. DBP stimulated 45Ca2+ influx in gills through the transitory receptor potential vanilloid 1 (TRPV1), and reverse-mode Na+/Ca2+ exchanger (NCX) activation, protein kinase C and K+ channels and sarco/endoplasmic reticulum Ca2+-ATPase (SERCA). These data suggest that in vivo short-term exposure of gills to low and high Ca2+ leads to 45Ca2+ influx and histopathological changes. Additionally, the DBP-induced rapid 45Ca2+ influx is mediated by TRPV1, NCX activation with the involvement of PKC, K+-channels and SERCA, thereby altering Ca2+ homeostasis.


Assuntos
Radioisótopos de Cálcio/metabolismo , Cálcio/metabolismo , Dibutilftalato/toxicidade , Brânquias/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/metabolismo , Animais , Cálcio/toxicidade , Dibutilftalato/metabolismo , Retículo Endoplasmático/metabolismo , Brânquias/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Canais de Cátion TRPV/metabolismo , Poluentes Químicos da Água/metabolismo
6.
Ecotoxicol Environ Saf ; 205: 111157, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829211

RESUMO

The fungicide carbendazim (CBM) has been applied all around the world but its potential adverse effects other than its recognized activity as endocrine disruptor in non target organisms have been scarcely studied. The aims of this work were (1) to use a battery of biomarkers that can reflect potential negative effects such as oxidative stress, genotoxicity, neurotoxicity or altered immune response; and (2) to examine biomarkers of detoxification by analyzing the gene expression of cytochrome P4501A1 (CYP1A1) and the multi-xenobiotic resistance protein P-glycoprotein (P-gp) in the freshwater fish Jenynsia multidentata exposed to environmentally relevant concentrations of CBM during 24 h. Fish exposed to 5 µg/L showed inhibition of GST activity and an increase of TBARs contents in gills, the organ of direct contact with waterborne contaminants. Genotoxicity - measured in peripheral blood-was evidenced by the increases of micronuclei frequency when fish were exposed to 5, 10 and 100 µg/L CBM and of nuclear abnormalities (NA) frequency at 0.05, 0.5, 5, 10 and 100 µg/L CBM. The expression inhibition of interleukin (IL-1ß) and tumor necrosis factor a (TNF-α) at 10, and 5 and 10 µg/L CBM, respectively, indicated an altered immune response. The expression of CYP1A1 was down regulated in liver at 10 µg/L and of P-gp at 5 µg/L CBM, indicating a possible slow on CBM metabolization. On the other hand, in gills CYP1A1 decreased at 5 and 10 µg/L while P-gp was induced at 5 and 100 µg/L CBM. Overall, most of these significant effects were detected below 10 µg/L CBM, in a range of realistic concentrations in aquatic ecosystems worldwide.


Assuntos
Benzimidazóis/toxicidade , Carbamatos/toxicidade , Ciprinodontiformes/metabolismo , Citocinas/metabolismo , Micronúcleos com Defeito Cromossômico/induzido quimicamente , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Animais , Antioxidantes/metabolismo , Biomarcadores/metabolismo , Ciprinodontiformes/genética , Ciprinodontiformes/imunologia , Citocromo P-450 CYP1A1/genética , Ecossistema , Água Doce/química , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Estresse Oxidativo/genética , Estresse Oxidativo/imunologia
7.
Aquat Toxicol ; 226: 105554, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32653664

RESUMO

The NF-E2-related factor 2 (Nrf2), an ubiquitous, evolutionarily conserved transcription factor, acts as a major sensor of oxidative stress in cells. In the present study, a Nrf2 homolog was newly identified in the thick shell mussel Mytilus coruscus. Accordingly, its functional role in antioxidant defense in response to acute benzo(a)pyrene (Bap) exposure was assessed. The newly identified McNrf2 affiliated to traditional Nrf2 family through Blast, multiple alignment and phylogenetic analysis. After acute exposure to Bap, antioxidants including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathine reductase (GR) were significantly induced in gills and digestive glands at both mRNA and enzymatic levels, and the expression of McNrf2 mRNA was also up-regulated. The analysis of correlating the expression of McNrf2 and the mRNA levels of these antioxidant genes showed positive ties, indicating that Nrf2 was needed for protracted induction of such genes. Further, the recombinant McNrf2 was produced through pET-32a prokaryotic system. After 50 µg/L Bap exposure, ROS generation and LPO level in gills of Nrf2 over-expressed mussels significantly decreased compared to Nrf2 wild-type mussels, as well as reduced ROS production in digestive glands. Collectively, these results show that Nrf2 pathway can provide protection from oxidative stress triggered by Bap in the thick shell mussel.


Assuntos
Antioxidantes/metabolismo , Benzo(a)pireno/toxicidade , Mytilus/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Catalase/metabolismo , Sistema Digestório/efeitos dos fármacos , Sistema Digestório/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Glutationa Peroxidase/metabolismo , Mytilus/metabolismo , Fator 2 Relacionado a NF-E2/genética , Estresse Oxidativo/genética , Filogenia , Superóxido Dismutase/metabolismo
8.
Aquat Toxicol ; 226: 105566, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32682194

RESUMO

Cytochrome P450 (CYP) enzymes play important roles in the detoxification and bioactivation of environmental contaminants and are involved in the responses to pollution in fish. In this study, we cloned four new CYP1 genes, CYP1A, CYP1B, CYP1C1, and CYP1C2, from black rockfish (Sebastes schlegelii), a dominant and economically important fish species in Korea. This species is at a significant risk of exposure to petrohydrocarbons, such as benzo[a]pyrene(B[a]P), due to frequent oil spills along the Korean coast. Quantitative PCR analysis of CYP1 gene transcription in 12 organs of the fish revealed tissue-specific expression patterns. CYP1A was significantly expressed in the liver, heart, kidneys, and muscle, and CYP1B was significantly expressed in the gills, muscle, and heart. CYP1C1 and CYP1C2 showed similar tissue expression patterns, with the highest levels in the muscle. Furthermore, exposure to an aryl hydrocarbon receptor (AHR) agonist, B[a]P, at 2, 20, and 200 mg/kg body weight showed significant dysregulation of the CYP1A, CYP1B, CYP1C1, and CYP1C2 expression levels in the gills, liver, kidneys, and spleen. The mRNA expression levels of CYP1A and CYP1B were upregulated by 450- and 17-fold, respectively, in the spleen. Compared with their levels in the control, CYP1C1 increased by 45-fold, while CYP1C2 remained unchanged in the gills, indicating differential effects of the polycyclic aromatic hydrocarbon on CYP1 expression in different fish organs. The results suggested that expression profiles of inducible CYP1 enzymes in S. schlegelii might be used as indicators for assessing aquatic contamination by AHR agonists. Determination of the basal and induced expression levels, as well as substrate specificity, of the four CYP1 enzymes may contribute to a better understanding of their roles in the metabolization of toxicants or drugs.


Assuntos
Benzo(a)pireno/toxicidade , Citocromo P-450 CYP1A1/metabolismo , Expressão Gênica/efeitos dos fármacos , Perciformes/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Citocromo P-450 CYP1A1/genética , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Perciformes/genética , Perciformes/crescimento & desenvolvimento , Receptores de Hidrocarboneto Arílico/metabolismo , República da Coreia
9.
Aquat Toxicol ; 226: 105565, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32682195

RESUMO

Pyrene (PYR) and fluorene (FLU) are among the sixteen priority Polycyclic Aromatic Hydrocarbons (PAH) of the United States Environmental Protection Agency and are both frequently detected in contaminated sites. Due to the importance of bivalve mollusks in biomonitoring programs and the scarce information on the biotransformation system in these organisms, the aim of this study was to investigate the effect of PYR and FLU at the transcriptional level and the enzymatic activities of some biotransformation systems in the Pacific oyster Crassostrea gigas, and to evaluate the histological effects in their soft tissues. Oysters C. gigas were exposed for 24 h and 96 h to PYR (0.25 and 0.5 µM) and FLU (0.6 and 1.2 µM). After exposure, transcript levels of cytochrome P450 coding genes (CYP1-like, CYP2-like, CYP2AU2, CYP356A1, CYP17α-like), glutathione S tranferase genes (omega GSTO-like and microsomal, MGST-like) and sulfotransferase gene (SULT-like), and the activity of ethoxyresorufin O-deethylase (EROD), Glutathione S-transferase (GST) and microssomal GST (MGST) were evaluated in gills. Histologic changes were also evaluated after the exposure period. PYR and FLU bioconcentrated in oyster soft tissues. The half-life time of PYR in water was lower than fluorene, which is in accordance to the higher lipophilicity and bioconcentration of the former. EROD activity was below the limit of detection in all oysters exposed for 96 h to PYR and FLU. The reproductive stage of the oysters exposed to PYR was post-spawn. Exposure to PYR caused tubular atrophy in digestive diverticula, but had no effect on transcript levels of biotransformation genes. However, the organisms exposed for 96 h to PYR 0.5 µM showed higher MGST activity, suggesting a protective role against oxidative stress in gills of oysters under higher levels of PYR in the tissues. Increased number of mucous cells in mantle were observed in oysters exposed to the higher FLU concentration, suggesting a defense mechanisms. Oysters exposed for 24 h to FLU 1.2 µM were in the ripe stage of gonadal development and showed higher transcript levels of CYP2AU2, GSTO-like and SULT-like genes, suggesting a role in the FLU biotransformation. In addition, after 96 h of exposure to FLU there was a significant increase of mucous cells in the mantle of oysters but no effect was observed on the EROD, total GST and MGST activities. These results suggest that PAH have different effects on transcript levels of biotransformation genes and enzyme activities, however these differences could also be related to the reproductive stage.


Assuntos
Crassostrea/efeitos dos fármacos , Fluorenos/toxicidade , Pirenos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Biotransformação/efeitos dos fármacos , Crassostrea/metabolismo , Citocromo P-450 CYP1A1/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Fluorenos/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Glutationa Transferase/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Pirenos/metabolismo , Poluentes Químicos da Água/metabolismo
10.
Aquat Toxicol ; 226: 105561, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32688145

RESUMO

In the aquatic environment, metals are present as mixtures, therefore studies on mixture toxicity are crucial to thoroughly understand their toxic effects on aquatic organisms. Common carp (Cyprinus carpio) were used to assess the effects of short-term Cu(II) and Cd(II) mixtures, using a fixed concentration of one of the metals, representing 25 % of its individual 96h-LC50 (concentration lethal for 50 % of the population) combined with a variable concentration of the other metal corresponding to 10, 25 or 50 % of its 96h-LC50, and vice versa. Our results showed a fast Cu and Cd bioaccumulation, with the percentage of increase in the order gill > liver > carcass. An inhibitory effect of Cu on Cd uptake was observed; higher Cu concentrations at fixed Cd levels resulted in a decreased accumulation of Cd. The presence of the two metal ions resulted in losses of total Na, K and Ca. Fish tried to compensate for the Na loss through the induction of the genes coding for Na+/K+-ATPase and H+-ATPase. Additionally, a counterintuitive induction of the gene encoding the high affinity copper transporter (CTR1) occurred, while a downregulation was expected to prevent further metal ion uptake. An induction of defensive mechanisms, both metal ion binding protein and anti-oxidant defences, was observed. Despite the metal accumulation and electrolyte loss, the low mortality suggest that common carp is able to cope with these metal levels, at least during a one-week exposure.


Assuntos
Bioacumulação/efeitos dos fármacos , Cádmio/toxicidade , Carpas/metabolismo , Cobre/toxicidade , Homeostase/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Cádmio/metabolismo , Carpas/genética , Cobre/metabolismo , Transportador de Cobre 1/genética , Transportador de Cobre 1/metabolismo , Eletrólitos/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Transporte de Íons , Dose Letal Mediana , Potássio/metabolismo , Sódio/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Poluentes Químicos da Água/metabolismo
11.
Aquat Toxicol ; 226: 105581, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32717676

RESUMO

Fluoxetine is a widely prescribed antidepressant that has been frequently detected in aquatic environments and is associated with a series of neurological, behavioural and neuroendocrine disruptions in nontarget organisms. However, studies on its effects in fish under realistic environmental conditions are still limited. In this study, we determined the influences of an environmentally relevant concentration of fluoxetine (100 ng/L) on crucian carp (Carassius auratus) in the presence of dissolved organic matter (DOM). Endpoints that were assessed included accumulation of fluoxetine and metabolite formation as well as related biological responses involving neurotransmission and metabolic processes. Fluoxetine was significantly bioconcentrated in the fish brain and liver and largely transformed to the active metabolite norfluoxetine. Brain neurotransmission processes related to serotonin and choline and liver metabolic status were simultaneously altered. DOM added at 1 mg/L had no effect on the accumulation of fluoxetine or its metabolites in different tissues of the fish. However, at 10 mg/L DOM facilitated fluoxetine and norfluoxetine accumulation in the liver, brain, kidney, gill and bile tissues of the fish. The neuroendocrine-disrupting effects on fish caused by fluoxetine were also enhanced by the co-addition of DOM at 10 mg/L. Binding with fluoxetine and the inhibition of metabolic functions caused by DOM may be responsible for this increase in effects. These findings imply that at high concentrations DOM can increase the toxicity of environmentally relevant concentrations of fluoxetine to fish.


Assuntos
Fluoxetina/análogos & derivados , Fluoxetina/toxicidade , Carpa Dourada/metabolismo , Substâncias Húmicas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Bioacumulação , Fluoxetina/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Substâncias Húmicas/análise , Fígado/efeitos dos fármacos , Fígado/metabolismo , Poluentes Químicos da Água/metabolismo
12.
PLoS One ; 15(7): e0236507, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730281

RESUMO

In air-breathing fish a reduction of gill surface area reduces the danger of losing oxygen taken up in the air-breathing organ (ABO) to hypoxic water, but it also reduces the surface area available for ion exchange, so that ion regulation may at least in part be transferred to other organs, like the kidney or the gut. In the air-breathing Arapaima gigas, gill lamellae regress as development proceeds, and starting as a water-breathing embryo Arapaima turns into an obligate air-breathing fish with proceeding development, suggesting that ion regulation is shifted away from the gills as the fish grows. In Arapaima the kidney projects medially into the ABO and thus, probably a unique situation among fishes, is in close contact to the gas of the ABO. We therefore hypothesized that the kidney would be predestined to adopt an increased importance for ion homeostasis, because the elevated ATP turnover connected to ion transport can easily be met by aerobic metabolism based on the excellent oxygen supply directly from the ABO. We also hypothesized that in gill tissue the reduced ion regulatory activity should result in a reduced metabolic activity. High metabolic activity and exposure to high oxygen tensions are connected to the production of reactive oxygen species (ROS), therefore the tissues exposed to these conditions should have a high ROS defense capacity. Using in vitro studies, we assessed metabolic activity and ROS production of gill, kidney and ABO tissue, and determined the activity of ROS degrading enzymes in small (~ 5g, 2-3 weeks old) and larger (~ 670 g, 3-4 months old) A. gigas. Comparing the three tissues revealed that kidney tissue oxygen uptake by far exceeded the uptake measured in gill tissue or ABO. ROS production was particularly high in gill tissue, and all three tissues had a high capacity to degrade ROS. Gill tissue was characterized by high activities of enzymes involved in the glutathione pathway to degrade ROS. By contrast, the tissues of the ABO and in particular the kidney were characterized by high catalase activities, revealing different, tissue-specific strategies in ROS defense in this species. Overall the differences in the activity of cells taken from small and larger fish were not as pronounced as expected, while at the tissue level the metabolic activity of kidney cells by far exceeded the activity of ABO and gill cells.


Assuntos
Peixes/fisiologia , Consumo de Oxigênio/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Brasil , Catalase/metabolismo , Brânquias/enzimologia , Brânquias/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Rim/metabolismo , Mitocôndrias/metabolismo , Superóxido Dismutase/metabolismo
13.
Am J Physiol Regul Integr Comp Physiol ; 319(3): R329-R342, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32697653

RESUMO

Peripheral chemosensitivity in fishes is thought to be mediated by serotonin-enriched neuroepithelial cells (NECs) that are localized to the gills of adults and the integument of larvae. In adult zebrafish (Danio rerio), branchial NECs are presumed to mediate the cardiorespiratory reflexes associated with hypoxia or hypercapnia, whereas in larvae, there is indirect evidence linking cutaneous NECs to hypoxic hyperventilation and hypercapnic tachycardia. No study yet has examined the ventilatory response of larval zebrafish to hypercapnia, and regardless of developmental stage, the signaling pathways involved in CO2 sensing remain unclear. In the mouse, a background potassium channel (TASK-2) contributes to the sensitivity of chemoreceptor cells to CO2. Zebrafish possess two TASK-2 channel paralogs, TASK-2 and TASK-2b, encoded by kcnk5a and kcnk5b, respectively. The present study aimed to determine whether TASK-2 channels are expressed in NECs of larval zebrafish and whether they are involved in CO2 sensing. Using immunohistochemical approaches, TASK-2 protein was observed on the surface of NECs in larvae. Exposure of larvae to hypercapnia caused cardiac and breathing frequencies to increase, and these responses were blunted in fish experiencing TASK-2 and/or TASK-2b knockdown. The results of these experiments suggest that TASK-2 channels are involved in CO2 sensing by NECs and contribute to the initiation of reflex cardiorespiratory responses during exposure of larvae to hypercapnia.


Assuntos
Dióxido de Carbono/metabolismo , Hipercapnia/metabolismo , Hipóxia/metabolismo , Células Neuroepiteliais/metabolismo , Canais de Potássio de Domínios Poros em Tandem/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Animais , Células Quimiorreceptoras/metabolismo , Brânquias/metabolismo , Hiperventilação/metabolismo , Células Neuroepiteliais/citologia , Oxigênio/metabolismo , Peixe-Zebra/fisiologia
14.
Ecotoxicol Environ Saf ; 201: 110871, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32559692

RESUMO

Microplastics (MPs) are of increasing concern for filter feeding marine and freshwater species. Additionally MPs can sorb hydrophobic contaminants from the water, potentially providing an additional pathway of exposure of aquatic species to contaminants. An acute 48 h laboratory study was conducted to investigate the effects of microplastics and triclosan, both individually and combined, on New Zealand's green-lipped mussel, Perna canaliculus. Biomarkers included clearance rate, oxygen uptake, byssus production; and superoxide dismutase (SOD) activity, glutathione-S-transferase (GST) activity and lipid peroxidation in the gill tissue. Microplastics and triclosan, both individually and combined significantly decreased oxygen uptake and byssus production. These physiological responses were not observed when the microplastics were spiked with triclosan. Triclosan, both alone and spiked to microplastics, increased mussel oxidative stress markers including SOD activity and lipid peroxidation. An enhanced effect was observed on the SOD enzyme activity when mussels were exposed to microplastics spiked with triclosan. No effects on the biochemical biomarkers were observed for mussels exposed to microplastic only. Microplastics enhanced the uptake of triclosan in mussel tissue compared with triclosan only treatments indicating that microplastics potentially provide an additional pathway of exposure to hydrophobic contaminants.


Assuntos
Microplásticos/toxicidade , Perna (Organismo)/efeitos dos fármacos , Triclosan/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Glutationa Transferase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Nova Zelândia , Estresse Oxidativo , Perna (Organismo)/metabolismo , Superóxido Dismutase/metabolismo , Triclosan/metabolismo , Poluentes Químicos da Água/metabolismo
15.
Aquat Toxicol ; 224: 105514, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32502847

RESUMO

Hypoxia and ammonia are unavoidable environmental factors in aquaculture, and have been shown cause various adverse effects in fish. In the present study, a two-factor crossover experiment was carried out to evaluate the combined effect of hypoxia and ammonia on oxidative stress and glucose metabolism endpoints in largemouth bass. The fish were divided into four experimental groups: hypoxia and ammonia group, hypoxia group, ammonia group, and control group. The results showed that hypoxia and ammonia exposures both induced antioxidant response and oxidative stress (superoxide dismutase [SOD] and catalase [CAT] activities increased first then decreased, and malondialdehyde accumulated) and anaerobic glycolysis (increase of blood glucose, decrease of liver glycogen, accumulation of lactate, and increased lactate dehydrogenase activity). In addition, hypoxia and ammonia upregulated antioxidant enzyme genes (Cu/ZnSOD, CAT, and GPx), apoptosis genes (caspase 3, caspase 8, and caspase 9), as well as inflammatory genes (interleukin [IL]-1ß and IL-8) and downregulated an anti-inflammatory gene (IL-10), suggesting that apoptosis and inflammation may be related to oxidative stress. The increased expression of GLUT1, LDH, and MCT4 were induced by hypoxia and ammonia, suggesting that anaerobic glycolysis was increased. Furthermore, fish suffering from hypoxia or ammonia exposure showed some changes in gill tissues histology, and the most severe lesions of gill tissues appeared in simultaneous exposure. Overall, both hypoxia and ammonia affected homeostasis, and simultaneous exposure led to more deleterious effects on largemouth bass than exposure to the individual stressors.


Assuntos
Amônia/toxicidade , Apoptose/efeitos dos fármacos , Bass/metabolismo , Glicemia/metabolismo , Hipóxia/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Apoptose/genética , Bass/genética , Bass/imunologia , Expressão Gênica/efeitos dos fármacos , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Brânquias/patologia , Inflamação/genética , Interleucinas/genética , Oxirredução , Estresse Oxidativo/genética
16.
Aquat Toxicol ; 224: 105521, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32504859

RESUMO

Microplastic pollution has drawn the attention of both scientists and the public regarding their potential ecotoxicological risks. In the present study, we carried out aqueous exposure experiments to adult zebrafish with polystyrene microplastics (5 µm) at a wide range of concentrations (0.001-20 mg/L, equals to 14.5∼2.9 × 105 particles/mL). Our results showed the gastrointestinal tract (GIT) was the dominant microplastic accumulation site in zebrafish, followed by the gill, whereas no microplastics were detected in the brain or muscle. Microplastic accumulation in GIT did not cause obvious damages to intestinal villi in general. However, the thickness of muscularis layer in the foregut reduced by 32% after 1 mg/L (1.45 × 104 particles/mL) microplastic exposure. As there were no signs of oxidative stress or other histological changes found in the fish, we further investigated the energy-supplying influential factors. We found that the zebrafish became hyperactive after microplastic exposure, whose swimming distance had increased to 1.3-2.4 folds than that of control, and also stayed at manic and active states much longer. The fish behavioural alteration is probably attributed to the particulate matter stimulation and the up-regulation of estrogen contents. Results also showed that the excessive movements of zebrafish also led to decreased glucose and acetaldehyde metabolite contents and increased amino acid amounts, which further proved the shortage of energy-supplying substances. Therefore, the present study suggests that micro-sized microplastics can induce obvious behavioural abnormality at concentrations that some other toxicological endpoints may not warn effects.


Assuntos
Comportamento Animal/efeitos dos fármacos , Microplásticos/toxicidade , Poliestirenos/toxicidade , Natação , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/metabolismo , Animais , Monitoramento Ambiental , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Microplásticos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Poliestirenos/metabolismo , Poluentes Químicos da Água/metabolismo
17.
J Environ Sci Health B ; 55(8): 749-755, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32558613

RESUMO

This study assessed the hematological, enzymatic and osmoregulatory responses of silver catfish (Rhamdia quelen) exposed to sublethal concentrations (1.125 and 3.750 µg/L) of a commercial thiamethoxam-containing insecticide used on rice crops. Groups of 6 fish per tank (in triplicate, n = 3, total 54 fish) were exposed for up to 96 h to different concentrations of the compound. After this period, fish were placed in clean water for 48 h. Two fish from each tank (6 per treatment) that had been exposed to the insecticide for 24 h were anesthetized with eugenol and blood was collected to evaluate hematological and biochemical parameters. Blood, liver and muscle were collected for determination of metabolic parameters, plasma cortisol, Cl-, Na+ and K+ levels and H+-ATPase and Na+/K+-ATPase activity in the gill. H+-ATPase activity was higher in fish exposed to 1.125 µg/L insecticide at 24 h compared to control (0.0 µg/L). Differences in cortisol levels were evidenced throughout the experimental period. These results indicated that exposure to the insecticide changed the hematological, biochemical and metabolic profile of the animals, suggesting concern about environmental safety. Therefore, we discourage the use of this pesticide in areas that come into contact with water bodies inhabited by fish.


Assuntos
Peixes-Gato/fisiologia , Inseticidas/toxicidade , Tiametoxam/toxicidade , Adenosina Trifosfatases/metabolismo , Animais , Peixes-Gato/sangue , Ecotoxicologia/métodos , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Hidrocortisona/sangue , Fígado/efeitos dos fármacos , Músculos/efeitos dos fármacos , Músculos/metabolismo , Potássio/metabolismo , Sódio/metabolismo , Testes de Toxicidade Aguda , Poluentes Químicos da Água/toxicidade
18.
PLoS One ; 15(5): e0232360, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32379772

RESUMO

The free radical nitric oxide (NO) is a powerful metabolic regulator in vertebrates and invertebrates. At cellular concentrations in the nanomolar range, and simultaneously reduced internal oxygen partial pressures (pO2), NO completely inhibits cytochrome-c-oxidase (CytOx) activity and hence mitochondrial- and whole-tissue respiration. The infaunal clam Arctica islandica regulates pO2 of hemolymph and mantle cavity water to mean values of <5 kPa, even in a completely oxygen-saturated environment of 21 kPa. These low internal pO2 values support a longer NO lifespan and NO accumulation in the body fluids and can thus trigger a depression of metabolic rate in the clams. Measurable amounts of NO formation were detected in hemocyte cells (~110 pmol NO 100-1 hemocytes h-1 at 6 kPa), which was not prevented in the presence of the NO synthase inhibitor L-NAME, and in the gill filaments of A. islandica. Adding a NO donor to intact gills and tissue homogenate significantly inhibited gill respiration and CytOx activity below 10 kPa. Meanwhile, the addition of the NO-oxidation product nitrite did not affect metabolic rates. The high nitrite levels found in the hemolymph of experimental mussels under anoxia do not indicate cellular NO production, but could be an indication of nitrate reduction by facultative anaerobic bacteria associated with tissue and/or hemolymph biofilms. Our results suggest that NO plays an important role in the initiation of metabolic depression during self-induced burrowing and shell closure of A. islandica. Furthermore, NO appears to reduce mitochondrial oxygen radical formation during surfacing and cellular reoxygenation after prolonged periods of hypoxia and anoxia.


Assuntos
Bivalves/metabolismo , Hipóxia/metabolismo , Óxido Nítrico/metabolismo , Animais , Antioxidantes/metabolismo , Bivalves/fisiologia , Respiração Celular , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Radicais Livres/metabolismo , Brânquias/metabolismo , Glutationa/metabolismo , Hemócitos/metabolismo , Hemolinfa/metabolismo , Longevidade/fisiologia , Mitocôndrias/metabolismo , Nitritos/metabolismo , Oxigênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo
19.
Bull Environ Contam Toxicol ; 104(6): 755-762, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32394051

RESUMO

We examined copper accumulation in the hemolymph, gills and hepatopancreas, and hemolymph osmolality, Na+ and Cl- concentrations, together with gill Na+/K+-ATPase and carbonic anhydrase activities, after dietary copper delivery (0, 100 or 500 Cu µg g-1) for 12 days in a fiddler crab, Minuca rapax. In contaminated crabs, copper concentration decreased in the hemolymph and hepatopancreas, but increased in the gills. Hemolymph osmolality and gill Na+/K+-ATPase activity increased while hemolymph [Na+] and [Cl-] and gill carbonic anhydrase activity decreased. Excretion likely accounts for the decreased hemolymph and hepatopancreas copper titers. Dietary copper clearly affected osmoregulatory ability and hemolymph Na+ and Cl- regulation in M. rapax. Gill copper accumulation decreased carbonic anhydrase activity, suggesting that dietary copper affects acid-base balance. Elevated gill Na+/K+-ATPase activity appears to compensate for the ion-regulatory disturbance. These effects of dietary copper illustrate likely impacts on semi-terrestrial species that feed on metal-contaminated sediments.


Assuntos
Bioacumulação , Braquiúros/efeitos dos fármacos , Cobre/metabolismo , Osmorregulação/efeitos dos fármacos , Poluentes Químicos da Água/metabolismo , Animais , Braquiúros/metabolismo , Cobre/análise , Exposição Dietética , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Hemolinfa/metabolismo , Hepatopâncreas/metabolismo , Transporte de Íons , Concentração Osmolar , Alimentos Marinhos , ATPase Trocadora de Sódio-Potássio/metabolismo , Poluentes Químicos da Água/análise
20.
Aquat Toxicol ; 223: 105482, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32371337

RESUMO

The use of online remote control for 24/7 behavioural monitoring can play a key role in estimating the environmental status of aquatic ecosystems. Recording the valve activity of bivalve molluscs is a relevant approach in this context. However, a clear understanding of the underlying disturbances associated with behaviour is a key step. In this work, we studied freshwater Asian clams after exposure to crude oil (measured concentration, 167 ± 28 µg·L-1) for three days in a semi-natural environment using outdoor artificial streams. Three complementary approaches to assess and explore disturbances were used: behaviour by high frequency non-invasive (HFNI) valvometry, tissue contamination with polycyclic aromatic hydrocarbons (PAH), and proteomic analysis. Two tissues were targeted: the pool adductor muscles - retractor pedal muscle - cerebral and visceral ganglia, which is the effector of any valve movement and the gills, which are on the frontline during contamination. The behavioural response was marked by an increase in valve closure-duration, a decrease in valve opening-amplitude and an increase in valve agitation index during opening periods. There was no significant PAH accumulation in the muscle plus nervous ganglia pool, contrary to the situation in the gills, although the latter remained in the low range of data available in literature. Major proteomic changes included (i) a slowdown in metabolic and/or cellular processes in muscles plus ganglia pool associated with minor toxicological effect and (ii) an increase of metabolic and/or cellular processes in gills associated with a greater toxicological effect. The nature of the proteomic changes is discussed in terms of unequal PAH distribution and allows to propose a set of explanatory mechanisms to associate behaviour to underlying physiological changes following oil exposure. First, the first tissues facing contaminated water are the inhalant siphon, the mantle edge and the gills. The routine nervous activity in the visceral ganglia should be modified by nervous information originating from these tissues. Second, the nervous activity in the visceral ganglia could be modified by its own specific contamination. Third, a decrease in nervous activity of the cerebral ganglia close to the mouth, including some kind of narcosis, could contribute to a decrease in visceral ganglia activity via a decrease or blockage of the downward neuromodulation by the cerebro-visceral connective. This whole set of events can explain the decrease of metabolic activity in the adductor muscles, contribute to initiate the catch mechanism and then deeply modify the valve behaviour.


Assuntos
Comportamento Animal/efeitos dos fármacos , Corbicula/efeitos dos fármacos , Corbicula/metabolismo , Petróleo/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Proteoma/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Ecossistema , Água Doce/química , Gânglios/efeitos dos fármacos , Gânglios/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Músculos/efeitos dos fármacos , Músculos/metabolismo , Proteômica
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