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Antioxidant responses and okadaic acid accumulation in Laeonereis acuta (Annelida) exposed to the harmful dinoflagellate Prorocentrum cf. lima. Toxicon 2021; 203:104-114. [PMID: 34662628 DOI: 10.1016/j.toxicon.2021.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/11/2021] [Accepted: 10/08/2021] [Indexed: 11/21/2022]
Abstract
We evaluated the accumulation of okadaic acid (OA), a diarrhetic toxin, and the antioxidant responses in the marine annelid Laeonereis acuta exposed to the benthic toxigenic dinoflagellate Prorocentrum cf. lima. Nontoxic Tetraselmis sp. was used as a control diet. Living cells of the two algae were supplied as food to animals kept in agar medium for 72 h. To assess the significance of the observed effects, our experimental design treated the algal species (diet), algal cell densities, and exposure time as fixed factors. Responses of the organisms were assessed through oxidative stress biomarkers (glutathione-S-transferase [GST], catalase [CAT], reduced glutathione [GSH] and lipid peroxidation [LPO]). Toxin accumulation was measured by LC-MS/MS in whole-body homogenates after 12, 24 and 72 h of exposure. Worms exposed to the toxigenic dinoflagellate gradually accumulated OA, with toxin levels directly related to the cell density of Prorocentrum cf. lima. Worms fed with Prorocentrum cf. lima exhibited decreased CAT activity, increased LPO levels - both interactively affected by algal species and time - and decreased GSH levels, which were interactively affected by algal species and cell density. Higher LPO levels, along with the inhibition of CAT and GSH, clearly indicated an oxidative stress situation in worms exposed to the toxigenic dinoflagellate. Laeonereis acuta accumulated moderate OA levels and may act as a vector of OA to food webs in estuarine areas under high Prorocentrum cf. lima abundance.
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Duan Y, Xiong D, Wang Y, Dong H, Huang J, Zhang J. Effects of Microcystis aeruginosa and microcystin-LR on intestinal histology, immune response, and microbial community in Litopenaeus vannamei. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 265:114774. [PMID: 32485489 DOI: 10.1016/j.envpol.2020.114774] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/28/2020] [Accepted: 05/07/2020] [Indexed: 06/11/2023]
Abstract
Microcystis aeruginosa (MA) is a primary hazardous cyanobacteria species in aquatic ecosystems that can produce microcystin-LR (MC-LR), which harms aquatic animals. The intestine is an important target tissue for MA and MC-LR. In this study, we investigated the effects of MA and MC-LR exposure on the intestinal microbiota variation and immune responses of Litopenaeus vannamei. Shrimp were experimentally exposed to MA and MC-LR for 72 h. The results showed that both MA and MC-LR exposure caused marked histological variation and apoptosis characteristics and increased oxidative stress in the intestine. Furthermore, the relative expression levels of antimicrobial peptide genes (ALF, Crus, Pen-3) decreased, while those of pro-inflammatory cytokines (MyD88, Rel, TNF-a), a pattern-recognition receptor (TLR4) and a mediator of apoptosis (Casp-3) increased. MA and MC-LR exposure also caused intestinal microbiota variation, including decreasing microbial diversity and disturbing microbial composition. Specifically, the relative abundance of Proteobacteria decreased in the two stress groups; that of Bacteroidetes decreased in the MA group but increased in the MC-LR group, while Tenericutes varied inversely with Bacteroidetes. Our results indicate that MA and MC-LR exposure causes intestinal histopathological and microbiota variations and induces oxidative stress and immune responses in L. vannamei. In conclusion, this study reveals the negative effects of MA and MC-LR on the intestinal health of shrimp, which should be considered in aquaculture.
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Affiliation(s)
- Yafei Duan
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510300, PR China
| | - Dalin Xiong
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510300, PR China
| | - Yun Wang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510300, PR China
| | - Hongbiao Dong
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510300, PR China
| | - Jianhua Huang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510300, PR China; Shenzhen Base of South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shenzhen, 518121, PR China
| | - Jiasong Zhang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510300, PR China.
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da Silva Toscano Saes RV, Moreira LB, Peres TF, Taniguchi S, Bícego MC, Marins RV, de Souza Abessa DM. Sub-lethal Responses of the Polychaete Armandia agilis in Whole-sediment Toxicity Testing. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:310-315. [PMID: 30688999 DOI: 10.1007/s00128-019-02556-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 01/20/2019] [Indexed: 06/09/2023]
Abstract
The present study assessed biochemical responses as sublethal endpoints in the polychaete Armandia agilis exposed to contaminated sediments to in order to assess its potential use as a test organism. Sediment samples from several locations at a dredging site were obtained and used in whole-sediment exposures. Samples were tested with A. agilis to determine the 10-day toxicity of the 100% sample and the enzymatic activity of catalase (CAT), glutathione-S-transferase (GST) and acetylcholinesterase (AChE) biochemical measurements made in whole-body homogenates of a subset of the surviving organisms. Biochemical responses reported in A. agilis were not statistically different from the reference site sediment, however, the integrated analysis demonstrated that contaminants bound to sediment samples influenced the sublethal effects.
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Affiliation(s)
| | - Lucas Buruaem Moreira
- Instituto de Ciências do Mar, Universidade Federal do Ceará (UFC), Meireles - Fortaleza, Av. da Abolição, Ceara, 3207, 60165-08, Brazil.
- Núcleo de Estudos em Poluição e Ecotoxicologia Aquática, Universidade Estadual Paulista (UNESP), Praça Infante Dom Henrique, s/n. São Vicente, Sao Paulo, 11330-900, Brazil.
| | - Tiago Farias Peres
- Instituto de Ciências do Mar, Universidade Federal do Ceará (UFC), Meireles - Fortaleza, Av. da Abolição, Ceara, 3207, 60165-08, Brazil
| | - Satie Taniguchi
- Instituto Oceanográfico, Universidade de São Paulo (USP), Praça do Oceanográfico, 191. São Paulo, Sao Paulo, 05508-120, Brazil
| | - Marcia Caruso Bícego
- Instituto Oceanográfico, Universidade de São Paulo (USP), Praça do Oceanográfico, 191. São Paulo, Sao Paulo, 05508-120, Brazil
| | - Rozane Valente Marins
- Instituto de Ciências do Mar, Universidade Federal do Ceará (UFC), Meireles - Fortaleza, Av. da Abolição, Ceara, 3207, 60165-08, Brazil
| | - Denis Moledo de Souza Abessa
- Instituto de Ciências do Mar, Universidade Federal do Ceará (UFC), Meireles - Fortaleza, Av. da Abolição, Ceara, 3207, 60165-08, Brazil
- Núcleo de Estudos em Poluição e Ecotoxicologia Aquática, Universidade Estadual Paulista (UNESP), Praça Infante Dom Henrique, s/n. São Vicente, Sao Paulo, 11330-900, Brazil
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Toxicological and biochemical responses of the earthworm Eisenia fetida to cyanobacteria toxins. Sci Rep 2017; 7:15954. [PMID: 29162925 PMCID: PMC5698456 DOI: 10.1038/s41598-017-16267-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 11/09/2017] [Indexed: 02/02/2023] Open
Abstract
Irrigation with eutrophic water containing cyanobacteria toxins poses a potential risk to soil animals. To evaluate ecotoxicological effect of microcystins (MCs) on earthworms, filter paper acute toxicity test, avoidance test and a 14-d artificial soil test were carried out. No acute toxicity was found in the filter paper test, and earthworms showed no avoidance response to MCs exposure. In the artificial soil test, Eisenia fetida were allowed to grow in presence or absence of MCs (0, 1, 10, 100, 1000 μg kg−1 of soil) for 1, 7, and 14 d. Results showed that MCs could bioaccumulated in earthworm. A stimulatory effect on catalase and glutathione oxidase activities induced by MCs was found on day 1, and both of them were significantly inhibited at 100 and 1000 μg kg−1 on days 14. The superoxide dismutase activity was relatively insensitive. Significant increase of malondialdehyde content and decrease of neutral red retention time were observed at 100 and 1000 μg kg−1 on days 7 and 14. Our results suggest that MCs induces oxidative stress on earthworms, which leads to disruption of the antioxidant system and lipid peroxidation, as well as alterations in lysosomal membrane stability.
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Diehl F, Ramos PB, Dos Santos JM, Barros DM, Yunes JS. Behavioral alterations induced by repeated saxitoxin exposure in drinking water. J Venom Anim Toxins Incl Trop Dis 2016; 22:18. [PMID: 27190499 PMCID: PMC4869272 DOI: 10.1186/s40409-016-0072-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 05/09/2016] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Blooms of the saxitoxin-producing cyanobacterium Cylindrospermopsis raciborskii have been contaminating drinking water reservoirs in Brazil for many years. Although acute effects of saxitoxin intoxication are well known, chronic deleterious outcomes caused by repeated saxitoxin exposure still require further investigation. The aim of the present work is to investigate the effects of consumption of drinking water contaminated with C. raciborskii for 30 days on learning and memory processes in rats. METHODS The effects of saxitoxin (3 or 9 μg/L STX equivalents) or cyanobacteria on behavior was determined using the open field habituation task, elevated plus maze anxiety model task, inhibitory avoidance task, and referential Morris water maze task. RESULTS No effects of saxitoxin consumption was observed on anxiety and motor exploratory parameters in the elevated plus maze and open field habituation tasks, respectively. However, groups treated with 9 μg/L STX equivalents displayed a decreased memory performance in the inhibitory avoidance and Morris water maze tasks. CONCLUSIONS These results suggest an amnesic effect of saxitoxin on aversive and spatial memories.
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Affiliation(s)
- Felipe Diehl
- Postgraduate Program in Physical, Chemical and Geological Oceanography, Institute of Oceanography, Federal University of Rio Grande (FURG), Rio Grande, RS Brazil ; Institute of Oceanography, Federal University of Rio Grande (FURG), Caixa Postal 474, Rio Grande, RS CEP 96203-900 Brazil
| | - Patricia Baptista Ramos
- Postgraduate Program in Physical, Chemical and Geological Oceanography, Institute of Oceanography, Federal University of Rio Grande (FURG), Rio Grande, RS Brazil
| | - Juliane Marques Dos Santos
- Postgraduate Program in Physical, Chemical and Geological Oceanography, Institute of Oceanography, Federal University of Rio Grande (FURG), Rio Grande, RS Brazil
| | - Daniela Martí Barros
- Postgraduate Program in Compared Animal Physiology, Institute of Biological Sciences, Federal University of Rio Grande (FURG), Rio Grande, RS Brazil
| | - João Sarkis Yunes
- Postgraduate Program in Physical, Chemical and Geological Oceanography, Institute of Oceanography, Federal University of Rio Grande (FURG), Rio Grande, RS Brazil
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Pavagadhi S, Balasubramanian R. Toxicological evaluation of microcystins in aquatic fish species: current knowledge and future directions. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 142-143:1-16. [PMID: 23948073 DOI: 10.1016/j.aquatox.2013.07.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Revised: 07/09/2013] [Accepted: 07/18/2013] [Indexed: 06/02/2023]
Abstract
Microcystins (MCs) are algal toxins produced intracellularly within the algal cells, and are subsequently released into the aquatic systems. An increase in the frequency and intensity of occurrence of harmful algal blooms has directed the global attention towards the presence of MCs in aquatic systems. The effects of MCs on fish have been verified in a number of studies including histological, biochemical and behavioral effects. The toxicological effects of MCs on different organs of fish are related to the exposure route (intraperitoneal injection, feeding or immersion), the mode of uptake (passive or active transport) as well as biotransformation and bioaccumulation capabilities by different organs. This paper reviews the rapidly expanding literature on the toxicological evaluation of MCs in fish from both field studies and controlled laboratory experimental investigations, integrates the current knowledge available about the mechanisms involved in MC-induced effects on fish, and points out future research directions from a cross-disciplinary perspective. In addition, the need to carry out systematic fish toxicity studies to account for possible interactions between MCs and other environmental pollutants in aquatic systems is discussed.
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Affiliation(s)
- Shruti Pavagadhi
- Singapore-Delft Water Alliance, National University of Singapore, Singapore 117576, Singapore; Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
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Abstract
Biomass and quality index of Chinese cabbage were investigated under the following treatment, control (CK), 25% biogas slurry + 75% fertilizer (Z-25%), 50% biogas slurry + 50% fertilizer (Z-50%), 75% biogas slurry + 25% fertilizer (Z-75%), and 100% biogas slurry (Z-100%). The results indicated that Z-25% significantly increased shoot height and fresh weight. But shoot height and fresh weight significantly decreased in a time-dependent manner when the concentration of the biogas slurry was greater than 50%. Vitamin C, soluble sugar, protein, and nitrite were measured to evaluate the effect of biogas slurry on the quality of Chinese cabbage. Z-25% treatment could remarkably increased the content of dehydroascorbate (DHA) and total Vc, whereas did not significantly affect reduced ascorbate (AsA) content compared to the CK for 60 d. The content soluble sugar and protein were significantly enhanced under Z-25% treatment. In addition, Z-25% effectively reduced nitrite content in Chinese cabbage. Biogas slurry with concentration more than 50% could not promote quality index of Chinese cabbage. To sum up, biogas slurry of water hyacinth could improve the growth and quality of Chinese cabbage under the optimal applied concentration.
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Gonçalves-Soares D, Zanette J, Yunes JS, Yepiz-Plascencia GM, Bainy ACD. Expression and activity of glutathione S-transferases and catalase in the shrimp Litopenaeus vannamei inoculated with a toxic Microcystis aeruginosa strain. MARINE ENVIRONMENTAL RESEARCH 2012; 75:54-61. [PMID: 21889198 DOI: 10.1016/j.marenvres.2011.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/23/2011] [Accepted: 07/27/2011] [Indexed: 05/21/2023]
Abstract
Microcystin (MC) produced during cyanobacteria blooms is notably toxic to human and wildlife. Conjugation with reduced glutathione (GSH) by glutathione S-transferase (GST) and the antioxidant enzymes defenses (e.g. catalase, CAT) are important biochemical defense mechanisms against MCs toxicity. We investigated the enzymatic activity of CAT and GST and the gene expression levels of CAT and eight GST isoforms in the hepatopancreas of the globally farmed shrimp Litopenaeus vannamei 48-h after injection with a sub-lethal dose of 100 μg kg⁻¹ of a toxic Microcystis aeruginosa extract. MCs caused up-regulation for GSTΩ, μ and a MAPEG isoform, by 12-, 2.8- and 1.8-fold, respectively, and increases in the total GST enzyme activity and CAT enzyme activity. The study points to the importance of further characterization for the L. vannamei GST isoforms and GST/CAT post-translational regulation processes to better understand the key mechanisms involved in the shrimp's defense against MC exposure.
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Affiliation(s)
- Daniela Gonçalves-Soares
- Departamento de Bioquímica, Núcleo de Estudos em Patologia Aquícola, Universidade Federal de Santa Catarina, Servidão Caminho do Porto, s/n, Itacorubi, Florianópolis, SC 88034-257, Brazil
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Pavagadhi S, Gong Z, Hande MP, Dionysiou DD, de la Cruz AA, Balasubramanian R. Biochemical response of diverse organs in adult Danio rerio (zebrafish) exposed to sub-lethal concentrations of microcystin-LR and microcystin-RR: a balneation study. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2012; 109:1-10. [PMID: 22207040 DOI: 10.1016/j.aquatox.2011.11.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 11/10/2011] [Accepted: 11/18/2011] [Indexed: 05/31/2023]
Abstract
The present study was carried out to examine the dose-response of microcystin-LR (MC-LR) and microcystin-RR (MC-RR) toxicity in adult Danio rerio (zebrafish) under balneation conditions at various time points. The differential responses of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST) as biomarkers were assessed for oxygen mediated toxicity in liver, gills, intestine and brain tissues of zebrafish exposed to dissolved MC-LR and MC-RR (0.1-10.0 μgl(-1)). To investigate the time related response of biomarkers, fish were sampled after 4, 7 and 15 days of exposure. Responses varied (i) between MC-LR and MC-RR (for certain groups), (ii) for different enzymes at all time points, and (iii) for different tissues. In general, most of the enzymes followed a bell shaped curve, with an abrupt increase in activity at a particular concentration. It was observed that upon exposure to MC-LR and MC-RR, some enzymes showed an adaptive response after the first time point wherein the enzyme activity increased in some tissues. The increase in enzyme activity is suggestive of their cellular and metabolic adaptations to the continued stress and toxin exposure. Enzyme activities in general increased at lower concentrations (≤ 5.0 μgl(-1)) and decreased at higher concentrations (≥ 5.0 μgl(-1)). An abrupt change in enzyme activities was observed at a particular concentration in all the tissue enzymes. For GPx and GR, there was a differential response in the case of fish exposed to MC-LR and MC-RR, which could be due to the difference in toxicity potentials of these cyanotoxins. In general, initial stress conditions were observed in most of the tissue enzymes following the exposure to microcystins (MCs). This observation suggests that MCs found in trace levels are likely to have deleterious effects on aquatic organisms and can trigger a variety of biochemical responses depending on their specific toxicity.
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Affiliation(s)
- Shruti Pavagadhi
- Singapore-Delft Water Alliance, National University of Singapore, Singapore 117576, Singapore
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Nagarajan M, Maruthanayagam V, Sundararaman M. A review of pharmacological and toxicological potentials of marine cyanobacterial metabolites. J Appl Toxicol 2011; 32:153-85. [PMID: 21910132 DOI: 10.1002/jat.1717] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/22/2011] [Accepted: 06/22/2011] [Indexed: 11/07/2022]
Abstract
Novel toxic metabolites from marine cyanobacteria have been thoroughly explored. Biologically active and chemically diverse compounds that could be hepatotoxic, neurotoxic or cytotoxic, such as cyclic peptides, lipopeptides, fatty acid amides, alkaloids and saccharides, have been produced from marine cyanobacteria. Many reports have revealed that biosynthesis of active metabolites is predominant during cyanobacterial bloom formation. Marine cyanobacterial toxic metabolites exhibit important biological properties, such as interfering in signal transduction either by activation or blockage of sodium channels or by targeting signaling proteins; inducing apoptosis by disrupting cytoskeletal proteins; and inhibiting membrane transporters, receptors, serine proteases and topoisomerases. The pharmacological importance of these metabolites resides in their proliferation and growth-controlling abilities towards cancer cell lines and disease-causing potent microbial agents (bacteria, virus, fungi and protozoa). Besides their toxic and pharmacological potentials, the present review discusses structural and functional resemblance of marine cyanobacterial metabolites to marine algae, sponges and mollusks.
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Affiliation(s)
- M Nagarajan
- Department of Marine Biotechnology, School of Marine Sciences, Bharathidasan University, Tiruchirappalli-620 024, Tamil Nadu, India
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Zhang M, Wang Z, Xu J, Liu Y, Ni L, Cao T, Xie P. Ammonium, microcystins, and hypoxia of blooms in eutrophic water cause oxidative stress and C-N imbalance in submersed and floating-leaved aquatic plants in Lake Taihu, China. CHEMOSPHERE 2011; 82:329-339. [PMID: 21075418 DOI: 10.1016/j.chemosphere.2010.10.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 10/01/2010] [Accepted: 10/03/2010] [Indexed: 05/30/2023]
Abstract
The heavy bloom of cyanobacteria is a disastrous consequence of freshwater eutrophication, and the bloom is highly toxic due to its secondary metabolites called microcystins (MCs). The release of organic substances from dense blooms causes an increase in NH4+ and decrease in oxygen in lake water. In the present study, the dynamics of physio-biochemical responses of five aquatic macrophytes to MCs and NH4+ stresses in Meiliang Bay were evaluated. The bay is one of the most seriously eutrophized areas dominated by the toxic cyanobacteria of Lake Taihu, China. The results demonstrate that aquatic macrophytes in Meiliang Bay are subjected to successive external stresses. From January to May, they are subjected to high NH4+ stress (>0.56 mg L(-1)), whereas from June to September or during dense blooms, the macrophytes experience both MC proliferation and moderate NH4+ toxicity (>0.3 mg L(-1)). In August, high NH4+ stress occurs along with hypoxia stress, whereas from September to December, the macrophytes experience moderate NH4+ stress, causing a serious imbalance in C-N metabolism and oxidative stress. Between the two aquatic plant life forms, floating-leaved plants are more resistant to the stresses of eutrophication than are submersed plants. Elevated MCs in the water column can aggravate oxidative stress and suppress the soluble protein contents of aquatic plants. High NH4+ in the water causes severe C and N imbalance in submersed macrophytes because of considerable carbon consumption for free amino acid synthesis. The superoxide dismutase activities of submersed macrophytes are suppressed by low light penetrating the eutrophic water, which might impair the antioxidative function of the plants. The findings of this study provide mainly field evidence that reveals the physical, chemical, and biological stresses on aquatic plants in bloom-prevailed eutrophic lakes.
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Affiliation(s)
- Meng Zhang
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory for Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
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Amado LL, Monserrat JM. Oxidative stress generation by microcystins in aquatic animals: why and how. ENVIRONMENT INTERNATIONAL 2010; 36:226-235. [PMID: 19962762 DOI: 10.1016/j.envint.2009.10.010] [Citation(s) in RCA: 203] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 09/09/2009] [Accepted: 10/27/2009] [Indexed: 05/28/2023]
Abstract
Microcystins (MICs) are potent toxins produced worldwide by cyanobacteria during bloom events. Phosphatases inhibition is a well recognized effect of this kind of toxins as well as oxidative stress. However, it is not fully understood why and how MICs exposure can lead to an excessive formation of reactive oxygen species (ROS) that culminate in oxidative damage. Some evidences suggest a close connection between cellular hyperphosphorylation state and oxidative stress generation induced by MICs exposure. It is shown, based on literature data, that MICs incorporation per se can be the first event that triggers glutathione depletion and the consequent increase in ROS concentration. Also, literature data suggest that hyperphosphorylated cellular environment induced by MICs exposure can modulate antioxidant enzymes, contributing to the generation of oxidative damage. This review summarizes information on MICs toxicity in aquatic animals, focusing on mechanistic aspects, and rise questions that in our opinion needs to be further investigated.
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Affiliation(s)
- L L Amado
- Curso de Pós-graduação em Ciências Fisiológicas - Fisiologia Animal Comparada, Cx. P. 474, CEP 96.201-900, Rio Grande, RS, Brazil
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Amado LL, Garcia ML, Ramos PB, Freitas RF, Zafalon B, Ferreira JLR, Yunes JS, Monserrat JM. A method to measure total antioxidant capacity against peroxyl radicals in aquatic organisms: application to evaluate microcystins toxicity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2009; 407:2115-23. [PMID: 19095287 DOI: 10.1016/j.scitotenv.2008.11.038] [Citation(s) in RCA: 270] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 09/09/2008] [Accepted: 11/14/2008] [Indexed: 05/20/2023]
Abstract
Determination of total antioxidant capacity, instead of the measurements of limited number of antioxidants, is very important for the understanding of how antioxidants interact with reactive oxygen species (ROS). Several techniques already exist with this propose, although some of them are extremely time-consuming. A new methodology is proposed, based on the detection of ROS by fluorometry (ex/em: 485/520 nm) employing 2',7'-dichlorofluorescein diacetate (H(2)DCF-DA) as substrate. Supernatant of homogenized samples from different organs (gill, muscle, liver, and brain) of the teleost fish Jenynsia multidentata (Anaplebidae) were exposed to peroxyl radicals generated by thermal (35 degrees C) decomposition of 2,2'-azobis (2 methylpropionamidine) dihydrochloride (ABAP, 4 mM). Different protein concentrations (0.5, 1, 2 and 8 mg/ml) were assayed to get the best signal and curve fitting of fluorescence data over time (30 min). Total antioxidant capacity against peroxyl radicals was estimated as the difference in ROS area with and without ABAP, relative to the fluorescence registered without ABAP. For application of this methodology, J. multidentata specimens were exposed for 24 h to microcystins, cyanotoxins known to induce oxidative stress. Almost all organs showed a lower antioxidant capacity (p<0.05) in samples with 8 mg proteins/ml, when compared to protein content of 1-2 mg/ml. In liver samples, higher (p<0.05) free iron content was determined in samples with 8 mg proteins/ml. Sensitivity test employing GSH spiked in homogenized samples showed the protocol efficiency in detecting total antioxidant capacity. In the test with microcystins a dose-dependent decrease (p<0.05) of antioxidant competence in gills and brain and an inverse result with liver samples were observed. The use of antioxidant defenses was efficient in avoiding oxidative damage, as the content of oxidized proteins was not altered. Data obtained show the potential of this new methodology to be used in ecotoxicological studies.
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Affiliation(s)
- Lílian Lund Amado
- Universidade Federal do Rio Grande - FURG, Instituto de Ciências Biológicas, Rio Grande, RS, Brazil
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