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1.
Toxics ; 11(8)2023 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-37624198

RESUMO

Changes in food quality can dramatically impair zooplankton fitness, especially in eutrophic water bodies where cyanobacteria are usually predominant. Cyanobacteria are considered a food with low nutritional value, and some species can produce bioactive secondary metabolites reported as toxic to zooplankton. Considering that cyanobacteria can limit the survival, growth and reproduction of zooplankton, we hypothesized that the dietary exposure of neotropical Daphnia species (D. laevis and D. gessneri) to saxitoxin-producing cyanobacteria impairs Daphnia feeding rates and fitness regardless of a high availability of nutritious algae. Life table and grazing assays were conducted with different diets: (1) without nutritional restriction, where neonates were fed with diets at a constant green algae biomass (as a nutritious food source), and an increasing cyanobacterial concentration (toxic and poor food source), and (2) with diets consisting of different proportions of green algae (nutritious) and cyanobacteria (poor food) at a total biomass 1.0 mg C L-1. In general, the presence of high proportions of cyanobacteria promoted a decrease in Daphnia somatic growth, reproduction and the intrinsic rate of population increase (r) in both diets with more pronounced effects in the nutritionally restricted diet (90% R. raciborskii). A two-way ANOVA revealed the significant effects of species/clone and treatments in both assays, with significant interaction between those factors only in the second assay. Regarding the grazing assay, only D. laevis was negatively affected by increased cyanobacterial proportions in the diet. In the life table assay with constant nutritious food, a reduction in the reproduction and the intrinsic rate of the population increase (r) of all species were observed. In conclusion, we found adverse effects of the toxic cyanobacterial strain R. raciborskii on Daphnia fitness, regardless of the constant amount of nutritious food available, proving the toxic effect of R. raciborskii and that the nutritional quality of the food has a greater influence on the fitness of these animals.

2.
Environ Toxicol Pharmacol ; 93: 103887, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35598755

RESUMO

Microcystin-LR (MC-LR) is a potent cyanotoxin that can reach several organs. However subacute exposure to sublethal doses of MC-LR has not yet well been studied. Herein, we evaluated the outcomes of subacute and sublethal MC-LR exposure on lungs. Male BALB/c mice were exposed to MC-LR by gavage (30 µg/kg) for 20 consecutive days, whereas CTRL mice received filtered water. Respiratory mechanics was not altered in MC-LR group, but histopathology disclosed increased collagen deposition, immunological cell infiltration, and higher percentage of collapsed alveoli. Mitochondrial function was extensively affected in MC-LR animals. Additionally, a direct in vitro titration of MC-LR revealed impaired mitochondrial function. In conclusion, MC-LR presented an intense deleterious effect on lung mitochondrial function and histology. Furthermore, MC-LR seems to exert an oligomycin-like effect in lung mitochondria. This study opens new perspectives for the understanding of the putative pulmonary initial mechanisms of damage resulting from oral MC-LR intoxication.


Assuntos
Microcistinas , Mitocôndrias , Animais , Ingestão de Alimentos , Pulmão , Masculino , Toxinas Marinhas , Camundongos , Microcistinas/metabolismo , Microcistinas/toxicidade , Oligomicinas/metabolismo , Oligomicinas/farmacologia
3.
J Chem Ecol ; 47(10-11): 847-858, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34569003

RESUMO

Cyanobacteria are photosynthetic microorganisms that compose phytoplankton and therefore have a trophic relationship with zooplankton, which represent an important link for energy flux in aquatic food webs. Several species can form blooms and produce bioactive metabolites known as cyanotoxins. However, the ecological and adaptative role of these toxins are still under debate. Many studies have addressed the cyanotoxins' function in defense against herbivory when grazing pressure by zooplankton plays a role in phytoplankton top-down control. Thus, the present study evaluated the ecophysiological responses of the cyanobacterial strain Microcystis aeruginosa NPLJ-4 underlying the chemical induced defense against the cladoceran Daphnia gessneri. Exposure to predator infochemicals consisted of cultures established in ASM-1 medium prepared in a filtrate from a culture of adults of D. gessneri at an environmentally relevant density. Daphnia infochemicals promoted a significant increase in toxin production by M. aeruginosa. However, no differences in growth were observed, despite a significant increase in both maximum photosynthetic efficiency and electron transport rate in response to zooplankton. Additionally, there was no significant variation in the production of exopolysaccharides. Overall, although a grazer-induced defense response was demonstrated, there were no effects on M. aeruginosa fitness, which maintained its growth in the presence of Daphnia alarm cues.


Assuntos
Daphnia/fisiologia , Cadeia Alimentar , Microcistinas/metabolismo , Microcystis/fisiologia , Feromônios/metabolismo , Animais , Daphnia/química , Comportamento Alimentar , Microcystis/química
4.
J Fish Biol ; 99(4): 1274-1279, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34159594

RESUMO

Cylindrospermopsin (CYN) is a cyanotoxin that has raised serious concerns about public health in many parts of the world. It can bioaccumulate and affect the health of aquatic organisms, but despite this, few studies have been conducted on CYN uptake and clearance in fish. In this paper, the authors evaluate the uptake and clearance of CYN in the muscle tissue and viscera of juvenile tilapia (Oreochromis niloticus) after exposure to aqueous extracts and whole cells of Cylindrospermopsis raciborskii (CYN-producer). CYN blended with commercial fish food, and three experiments were conducted. In the first trial, fish food, and aqueous extracts containing 0.31 µg CYN g-1 of food per day, was administered to tilapia for 15 days. In the second trial, fish were provided food and intact cells (5.4 µg CYN g-1 of food per day) for 15 days. In the last trial, they were provided fish food and aqueous extracts (0.8 µg CYN g-1 of food per day) for 12 days, and for the next 10 days, the animals were fed food without toxic cell extracts (to simulate a clearance period). The concentration of CYN in muscle tissue and viscera was analysed using ELISA. In the case of juvenile tilapia, the presence of CYN was higher in viscera than in muscle tissue, and the toxin remained in the tissues even after 10 days without the addition of contaminated food. The results suggest that tilapia represents a potential source of CYN transfer through the food web, and this shows the need for a continuous monitoring of this compound in organisms that are used for human and animal consumption.


Assuntos
Ciclídeos , Alcaloides , Animais , Toxinas de Cianobactérias , Cylindrospermopsis , Laboratórios , Uracila
5.
Braz J Microbiol ; 52(2): 773-785, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33791954

RESUMO

As part of the phytoplankton of marine and freshwater environments around the world, cyanobacteria interact with viruses (cyanophages) that affect their abundance and diversity. Investigations focusing on cyanophages co-occurring with freshwater cyanobacteria are scarce, particularly in Brazil. The aim of this study was to assess the diversity of cyanophages associated with a Microcystis-dominated cyanobacterial bloom in a tropical reservoir. Samples were processed as viral fractions of water and cellular fractions, and temporal fluctuations in the abundance of Ma-LMM01-type cyanophages and their Microcystis hosts were determined by qPCR. We applied shotgun metagenomics to obtain a wider characterization of the cyanophage community. During the study period, Microcystis gene copies were quantified in all cellular fractions, and the copy number of the Ma-LMM01 phage gene tended to increase with host abundance. Metagenomic analysis demonstrated that Caudovirales was the major viral order associated with the cyanophage families Myoviridae (34-88%), Podoviridae (3-42%), and Siphoviridae (6-23%). The metagenomic analysis results confirmed the presence of Microcystis cyanophages in both viral and cellular fractions and demonstrated a high relative abundance of picocyanobacteria-related viruses and Prochlorococcus (36-52%) and Synechococcus (37-50%) phages. For other main cyanobacterial genera, no related cyanophages were identified, which was probably due to the scarce representation of cyanophage sequences in databanks. Thus, the studied reservoir hosted a diverse cyanophage community with a remarkable contribution of phages related to picoplanktonic cyanobacteria. These results provide insights that motivate future sequencing efforts to assess cyanophage diversity and recover complete genomes.


Assuntos
Bacteriófagos/isolamento & purificação , Biodiversidade , Cianobactérias/virologia , Água Doce/virologia , Bacteriófagos/classificação , Bacteriófagos/genética , Brasil , Cianobactérias/classificação , Cianobactérias/genética , Cianobactérias/crescimento & desenvolvimento , Água Doce/microbiologia , Genoma Viral , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Microcystis/virologia , Filogenia , Recursos Hídricos
6.
Curr Microbiol ; 78(6): 2345-2354, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33913000

RESUMO

In the Amazon, the leaching from soil left unprotected by deforestation increases the entry of iron, among other elements, in aquatic ecosystems, which can cause cyanobacterial blooms. This study aimed to investigate the physiological response of a strain of Microcystis panniformis to iron variation. The strain was isolated from a reservoir located in the Western Amazon and produces microcystin-LR. After a period of iron deprivation, the cultures were submitted to three conditions: control (223 µgFe.L-1), treatment with 23 µgFe.L-1, and absence of iron. At regular intervals for eight days, the cell density, levels of chlorophyll a and microcystins were determined. On the second and fourth day, transcription of genes responsive to iron limitation was quantified. Starting on the fourth day of the experiment, the different iron concentrations affected growth, and on the eighth day in the iron-free condition cell density was 90% lower than in control. Chlorophyll cell quota in 23 µgFe.L-1 and control presented similar values, while without iron the cells became chlorotic as of the fourth day Toxin concentration in cells grow in 0 µgFe.L-1 in relation to the control. Higher transcription levels of the feo and fut genes were observed in the 0 µgFe.L-1 and 23 µgFe.L-1 treatments, indicating that the cells were activating high-affinity capture systems to reestablish an adequate concentration of intracellular iron. The increasing deforestation in the Jamari River Basin (Amazon region), can contribute to the occurrence of toxic cyanobacterial blooms due to the greater entrance of iron in water bodies.


Assuntos
Microcistinas , Microcystis , Clorofila A , Ecossistema , Ferro , Microcystis/genética
7.
Rio de Janeiro; s.n; 2019. 201 p. ilus.
Tese em Português | LILACS | ID: biblio-1053045

RESUMO

O ensino básico brasileiro está em fase de transição de um ensino bancário centrado no professor, conteudista, fragmentado e descontextualizado, pautado em livros didáticos para um ensino centrado no educando baseado em estudo ativo com metodologias diferenciadas. Uma das razões para essa mudança é despertar no educando o interesse pelo estudo. Alinhada a essa problemática as instituições de pesquisas com o objetivo de despertar nos jovens de educação básica o interesse pelas ciências investem em Programas de pré-iniciação cientifica, que são desenvolvidos pedagogicamente pela metodologia de projetos, que é uma metodologia ativa. Toda metodologia ativa tem sua base em teorias construtivistas, na qual o estudante é protagonista na construção do conhecimento e o professor tem o papel de mediador. Esta pesquisa é um estudo de caso qualitativo, cujo objetivo foi estudar as contribuições educacionais e sociais do "Programa Jovens Talentos para a Ciência/FAPERJ" no período de 2010 a 2017, na cidade de Miracema. Portanto, foram identificados: (i) as contribuições do Programa na ótica dos participantes (estudantes, docente e comunidade); (ii) os projetos desenvolvidos nesse período, seus produtos e impactos na sociedade miracemense; (iii) os documentos relacionados ao Programa, que foram catalogados e inseridos em um banco de dados. Nesse período participaram do Programa 137 jovens, desses dez, ainda, não concluíram o ensino médio. Então, os resultados apresentados são de 127 JT. O quantitativo de estudantes do sexo feminino foi de 55% e 45% masculino. 94,49% ingressaram no nível superior, desses 64,53% estão em universidade públicas e 56,47% em instituições privadas, com bolsas de 100% pelo Programa Universidade para todos (PROUNI). 30% optaram pela área de Ciências da Saúde e 19,16% pelas Ciências Biológicas.


Durante esse período foram desenvolvidos 93 projetos, sendo que 32, ainda estão ativos. Os projetos abordavam a realidade histórica, literária, social, ambiental e/ou de saúde da cidade. A maioria dos estudantes, orientadores e da comunidade escolar afirmou que o Programa foi uma ótima experiência, que contribuiu na vida pessoal, intelectual e profissional dos estudantes, assim como favoreceu na escolha da carreira profissional, no desenvolvimento da criticidade, da autonomia, da oralidade. Além disso proporcionou mais responsabilidade, comprometimento com os estudos, a trabalhar em equipe, na relação consigo mesmo e com o outro, dentre outras capacidades. As críticas ao Programa foram: o pequeno quantitativo de vagas, falta de laboratório com equipamentos científicos e na necessidade de aumento no valor da bolsa. Os participantes não apresentaram sugestões de melhoria para o Programa. Acreditamos que o sucesso do Programa, em Miracema se deve a metodologia empregada que é de cunho construtivista e ao fato dos projetos que foram desenvolvidos estarem diretamente relacionados a realidade dos estudantes. As práticas construtivistas favorecem o protagonismo dos estudantes na construção do conhecimento, da autonomia e na tomada de decisão. A tomada de decisões pelos estudantes e por meio de seus atos. Transformar a realidade em que está inserido é um dos objetivos dos Parâmetros Curriculares Nacionais para a formação do cidadão crítico e autônomo. (AU)


Assuntos
Humanos , Instituições Acadêmicas , Ciência , Ensino , Ensino Fundamental e Médio , Acreditação de Programas
8.
Toxicon ; 141: 1-8, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29097245

RESUMO

Microcystin-LR (MC-LR) can cause serious injuries upon short- and long-term exposures that can be prevented by LASSBio-596 (LB-596), an anti-inflammatory compound. We aimed to test LB-596 following subchronic exposure to MC-LR. Swiss mice received 10 intraperitoneal injections of distilled water (DW) or MC-LR (20 µg/kg bw) every 2 days. On the 10th injection animals receiving DW were gavaged with DW or 50 mg/kg bw of LB-596 for 1 or 7 days (C1D, C7D, CL1D and CL7D groups), whereas those exposed to MC-LR received either DW or 50 mg/kg of LB-596 for 1 or 7 days (T1D, T7D, TL1D and TL7D groups). Twelve hours after the last gavage we assessed respiratory mechanics, and extracted lung and liver for histology, apoptosis, inflammatory biomarkers and MC-LR content. C1D, C7D, CL1D and CL7D were all similar. Mechanical parameters were significantly higher in T1D and T7D compared to the other groups. LB-596 reversed these changes on day 1 of administration. LB-596 reduced inflammatory mediators in lung and liver on day 1 of treatment. On day 7 apoptosis in liver and lung fell even more. Briefly, 7-day administration completely reversed lung and liver changes.


Assuntos
Anti-Inflamatórios/administração & dosagem , Fígado/patologia , Pulmão/patologia , Microcistinas/antagonistas & inibidores , Ácidos Ftálicos/administração & dosagem , Sulfonamidas/administração & dosagem , Administração Oral , Animais , Anti-Inflamatórios/uso terapêutico , Apoptose/efeitos dos fármacos , Inflamação , Fígado/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Masculino , Toxinas Marinhas , Camundongos , Microcistinas/análise , Microcistinas/toxicidade , Ácidos Ftálicos/uso terapêutico , Mecânica Respiratória/efeitos dos fármacos , Sulfonamidas/uso terapêutico , Fatores de Tempo
9.
Genome Announc ; 5(43)2017 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-29074674

RESUMO

We report here the draft genome sequences of two Brazilian strains of Cylindrospermopsis raciborskii, a saxitoxin-producer (CYRF) and a non-saxitoxin producer (CYLP), with each strain comprising one assembled scaffold. We revealed differences in the compositions of gene members coding for membrane transporters and antioxidant activities between the strains.

10.
Toxicon ; 112: 51-8, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26844922

RESUMO

We had previously shown that microcystin-LR (MCLR) could induce lung and liver inflammation after acute exposure. The biological outcomes following prolonged exposure to MCLR, although more frequent, are still poorly understood. Thus, we aimed to verify whether repeated doses of MCLR could damage lung and liver and evaluate the dose-dependence of the results. Male Swiss mice received 10 intraperitoneal injections (i.p.) of distilled water (60 µL, CTRL) or different doses of MCLR (5 µg/kg, TOX5), 10 µg/kg (TOX10), 15 µg/kg (TOX15) and 20 µg/kg (TOX20) every other day. On the tenth injection respiratory mechanics (lung resistive and viscoelastic/inhomogeneous pressures, static elastance, and viscoelastic component of elastance) was measured. Lungs and liver were prepared for histology (morphometry and cellularity) and inflammatory mediators (KC and MIP-2) determination. All mechanical parameters and alveolar collapse were significantly higher in TOX5, 10, 15 and 20 than CTRL, but did not differ among them. Lung inflammatory cell content increased dose-dependently in all TOX groups in relation to CTRL, being TOX20 the largest. The production of KC was increased in lung and liver homogenates. MIP-2 increased in the liver of all TOX groups, but in lung homogenates it was significantly higher only in TOX20 group. All TOX mice livers showed steatosis, necrosis, inflammatory foci and a high degree of binucleated hepatocytes. In conclusion, sub-chronic exposure to MCLR damaged lung and liver in all doses, with a more important lung inflammation in TOX20 group.


Assuntos
Toxinas Bacterianas/toxicidade , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Fígado/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Pneumonia/induzido quimicamente , Animais , Toxinas Bacterianas/administração & dosagem , Toxinas Bacterianas/isolamento & purificação , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/patologia , Doença Hepática Induzida por Substâncias e Drogas/fisiopatologia , Quimiocina CXCL2/agonistas , Quimiocina CXCL2/metabolismo , Quimiocinas/agonistas , Quimiocinas/metabolismo , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/toxicidade , Hepatite/etiologia , Injeções Intraperitoneais , Fígado/imunologia , Fígado/metabolismo , Fígado/patologia , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Masculino , Toxinas Marinhas/administração & dosagem , Toxinas Marinhas/isolamento & purificação , Camundongos , Microcistinas/administração & dosagem , Microcistinas/isolamento & purificação , Microcystis/química , Tamanho do Órgão/efeitos dos fármacos , Fosfoproteínas Fosfatases/antagonistas & inibidores , Pneumonia/metabolismo , Pneumonia/patologia , Distribuição Aleatória , Testes de Toxicidade Subcrônica
11.
ScientificWorldJournal ; 2015: 834197, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26380369

RESUMO

We studied the effect of temperature (18 and 30°C) on growth and on the exploitation and interference competition of three species: Microcystis aeruginosa (MIJAC), Planktothrix agardhii (PAT), and Cyclotella meneghiniana (CCAP). Coculturing the organisms in batch systems allowed for the examination of both competitive interactions, while the interference competition was studied in cross-cultures. The experiments were done during 10-12 days, and samples were taken for chlorophyll-a analysis, using PHYTO-PAM. The temperature did not influence exploitation competition between MIJAC and other competitors and it was the best competitor in both temperatures. PAT presented higher growth rates than CCAP in competition at 18 and 30°C. The temperature influenced the interference competition. The growth of MIJAC was favored in strains exudates at 30°C, while CCAP was favored at 18°C, revealing that the optimum growth temperature was important to establish the competitive superiority. Therefore, we can propose two hypotheses: (i) different temperatures may results in production of distinct compounds that influence the competition among phytoplankton species and (ii) the target species may have different vulnerability to these compounds depending on the temperature. At last, we suggest that both the sensitivity and the physiological status of competing species can determine their lasting coexistence.


Assuntos
Cianobactérias/fisiologia , Diatomáceas/fisiologia , Microcystis/fisiologia , Fitoplâncton/fisiologia , Técnicas de Cultura de Células , Clorofila/análogos & derivados , Clorofila/biossíntese , Luz , Interações Microbianas , Temperatura
12.
Toxicon ; 94: 29-35, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25528385

RESUMO

The cyanotoxin cylindrospermopsin (CYN) has lately been reported with a notorious toxicity to mammals. LASSBio-596 is a compound with anti-inflammatory actions. We aimed at evaluating the therapeutic effects of LASSBio-596 in a model of CYN-induced lung injury. Protocol #1: BALB/c mice received intratracheally (i.t.) 50-µL of saline or semi-purified extract of CYN (70 µg/kg). 18 h later, animals that received saline were gavaged with saline (SALSAL) or 50 mg/kg of LASSBio-596 (SALLAS), and mice that received CYN were gavaged with either saline (TOXSAL) or 50 mg/kg of LASSBio-596 (TOXLAS). Pulmonary mechanics was measured 6 h after gavage. Lungs were prepared for histology and inflammatory mediators determination. Protocol #2: Mice received 50-µL of CYN (70 µg/kg, i.t.) and 18 h later were gavaged with saline (NOT TREATED), or 50 mg/kg of LASSBio-596 (TREATED). Survival rates and pulmonary mechanics of the survivors were assessed. CYN exposure increased mechanical components, alveolar collapse, PMN cells and fiber deposition in the lungs, as well as the production of IL-1ß, IL-6 and KC in Protocol #1. LASSBio-596 attenuated those changes. TREATED mice in Protocol #2 presented significantly higher survival rates and tended to improve lung mechanics. Briefly, LASSBio-596 showed positive effects in mice exposed to CYN.


Assuntos
Anti-Inflamatórios/uso terapêutico , Lesão Pulmonar/tratamento farmacológico , Ácidos Ftálicos/uso terapêutico , Sulfonamidas/uso terapêutico , Uracila/análogos & derivados , Alcaloides , Animais , Anti-Inflamatórios/efeitos adversos , Toxinas Bacterianas , Toxinas de Cianobactérias , Lesão Pulmonar/induzido quimicamente , Lesão Pulmonar/patologia , Camundongos Endogâmicos BALB C , Ácidos Ftálicos/efeitos adversos , Sulfonamidas/efeitos adversos , Análise de Sobrevida , Uracila/toxicidade
13.
Mar Drugs ; 11(8): 2949-63, 2013 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-23955286

RESUMO

The cosmopolitan and increasing distribution of Cylindrospermopsis raciborskii can be attributed to its ecophysiological plasticity and tolerance to changing environmental factors in water bodies. In reservoirs in the semi-arid region of Brazil, the presence and common dominance of C. raciborskii have been described in waters that are considered hard. We investigated the response of a Brazilian C. raciborskii strain to water hardness by evaluating its growth and saxitoxin production. Based on environmental data, a concentration of 5 mM of different carbonate salts was tested. These conditions affected growth either positively (MgCO3) or negatively (CaCO3 and Na2CO3). As a control for the addition of cations, MgCl2, CaCl2 and NaCl were tested at 5 or 10 mM, and MgCl2 stimulated growth, NaCl slowed but sustained growth, and CaCl2 inhibited growth. Most of the tested treatments increased the saxitoxin (STX) cell quota after six days of exposure. After 12 days, STX production returned to concentrations similar to that of the control, indicating an adaptation to the altered water conditions. In the short term, cell exposure to most of the tested conditions favored STX production over neoSTX production. These results support the noted plasticity of C. raciborskii and highlight its potential to thrive in hard waters. Additionally, the observed relationship between saxitoxin production and water ion concentrations characteristic of the natural environments can be important for understanding toxin content variation in other harmful algae that produce STX.


Assuntos
Cylindrospermopsis/metabolismo , Saxitoxina/biossíntese , Água/química , Brasil , Cloreto de Cálcio/química , Cylindrospermopsis/crescimento & desenvolvimento , Cloreto de Magnésio/química , Cloreto de Sódio/química , Fatores de Tempo
14.
Braz. j. microbiol ; 42(4): 1547-1559, Oct.-Dec. 2011. graf, tab
Artigo em Inglês | LILACS | ID: lil-614621

RESUMO

Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju is a freshwater cyanobacterium of worldwide distribution. In the North-eastern region of Brazil many eutrophic water reservoirs are characterized by the dominance of C. raciborskii, with recurrent occurrence of blooms. These water bodies have high conductivity due to a high ionic concentration, and are defined as hard (with high values of CaCO3). In this study, we investigated the long-term effect (12 days) of high calcium concentration (8 mM Ca2+) on C. raciborskii (T3 strain) growth, morphology, toxin content, and metabolism. Changes in protein expression profiles were investigated by proteomic analysis using 2D gel electrophoresis and mass spectrometry. A continued exposure to calcium had a pronounced effect on C. raciborskii (T3): it limited growth, decreased thricome length, increased chlorophyll-a content, altered toxin profile (although did not affect PST content, saxitoxin + neosaxitoxin), and inhibited the expression of proteins related to primary metabolism.


Assuntos
Toxinas Bacterianas , Cylindrospermopsis/crescimento & desenvolvimento , Cylindrospermopsis/isolamento & purificação , Cylindrospermopsis/metabolismo , Eletroforese em Gel de Ágar , Proteoma/análise , Tanques Elevados/análise , Microbiologia Ambiental , Concentração de Íons de Hidrogênio , Métodos , Métodos , Amostras de Água
15.
Braz J Microbiol ; 42(4): 1547-59, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24031789

RESUMO

Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju is a freshwater cyanobacterium of worldwide distribution. In the North-eastern region of Brazil many eutrophic water reservoirs are characterized by the dominance of C. raciborskii, with recurrent occurrence of blooms. These water bodies have high conductivity due to a high ionic concentration, and are defined as hard (with high values of CaCO3). In this study, we investigated the long-term effect (12 days) of high calcium concentration (8 mM Ca(2+)) on C. raciborskii (T3 strain) growth, morphology, toxin content, and metabolism. Changes in protein expression profiles were investigated by proteomic analysis using 2D gel electrophoresis and mass spectrometry. A continued exposure to calcium had a pronounced effect on C. raciborskii (T3): it limited growth, decreased thricome length, increased chlorophyll-a content, altered toxin profile (although did not affect PST content, saxitoxin + neosaxitoxin), and inhibited the expression of proteins related to primary metabolism.

16.
Toxicon ; 56(7): 1247-56, 2010 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-20362607

RESUMO

The acute poisoning of chronic renal patients during hemodialysis sessions in 1996 in Caruaru City (Pernambuco State, Brazil) stimulated an intensive search for the cause of this severe complication. This search culminated in the identification of microcystins (MC), hepatotoxic cyclic heptapeptides produced by cyanobacteria, as the causative agents. More than ten years later, additional research data provides us with a better understanding of the factors related to cyanobacterial bloom occurrence and production of MC in Brazil and other South American countries. The contamination of water bodies and formation of toxic blooms remains a very serious concern, especially in countries in which surface water is used as the main source for human consumption. The purpose of this review is to highlight the discoveries of the past 15 years that have brought South American researchers to their current level of understanding of toxic cyanobacteria species and that have contributed to their knowledge of factors related to MC production, mechanisms of action and consequences for human health and the environment.


Assuntos
Toxinas Bacterianas/análise , Ecossistema , Microcistinas/análise , Água/química , Toxinas Bacterianas/química , Brasil , Monitoramento Ambiental , Humanos , Microcistinas/química , América do Sul , Microbiologia da Água , Abastecimento de Água
17.
Porto Alegre; Programa de Pós-Graduação em Ciências Farmacêuticas; 2009. 127 p. tab, graf.
Monografia em Português | LILACS, AHM-Acervo, TATUAPE-Acervo | ID: lil-642529
18.
Porto Alegre; Programa de Pós-Graduação em Ciências Farmacêuticas; 2009. 127 p. tab, graf.
Monografia em Português | Sec. Munic. Saúde SP, AHM-Acervo, TATUAPE-Acervo | ID: sms-2249
19.
Toxicon ; 47(7): 774-9, 2006 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-16626773

RESUMO

Microcystin (MC) has been found in several areas of the world. In addition to its hepatotoxicity, microcystin may have an immunomodulatory effect. Considering that patients receiving hemodialysis may be chronically exposed to variable concentrations of MC, and that they present important changes in this immune response, we have assessed the effect of MC on the function of leukocytes. Polymorphonuclear leukocytes isolated from healthy volunteers (HV) and patients receiving hemodialysis (HD) were incubated with microcystin (10 microg/L) for 24h and evaluated for reactive oxygen species production (ROS), phagocytosis and apoptosis. Monocytes incubated with and without LPS (100 ng/mL) and microcystin for 24h were assessed for TNFalpha and IL-10 production. Leukocytes of HV presented an increase in apoptosis rates and leukocytes from HD exhibited a lower production of oxygen-reactive species, both spontaneously and after stimulus with S. aureus, when compared with leukocytes incubated without toxin. Monocytes presented an increase in cytokine production after stimulation by LPS in both groups, but there was no difference between the groups with and without MC that were incubated with or without LPS. Low concentrations of microcystin can induce mild changes in leukocyte function of HV and HDP, particularly in the ability to produce ROS.


Assuntos
Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/efeitos dos fármacos , Peptídeos Cíclicos/farmacologia , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Interleucina-10/metabolismo , Falência Renal Crônica/terapia , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Microcistinas , Fagocitose/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Diálise Renal , Fator de Necrose Tumoral alfa/metabolismo
20.
Rio de Janeiro; s.n; 2006. xv,130 p. ilus, mapas, tab, graf.
Tese em Português | LILACS | ID: lil-453422

RESUMO

Este trabalho de pesquisa tem como tema o estudo da implantação de um projeto que trouxe uma nova metodologia ligada à melhoria do ensino das ciências em sua interação com a linguagem, adotada em um colégio estadual localizado no interior do estado do Rio de Janeiro. Buscou-se realizar um acompanhamento avaliativo do projeto ABC na Educação Científica – Mão na Massa, a fim de verificar sua contribuição para o estímulo a um processo investigativo e ao desenvolvimento da argumentação oral e escrita. Buscamos avaliar se algumas características básicas do projeto eram efetivamente desenvolvidas, tais como a metodologia investigativa a partir de desafios e um maior estímulo às interações em sala de aula. Por meio de registro de fotografias, áudio e vídeo foi possível enfatizar que nosso trabalho valorizou situações de questionamento e promoveu mudanças de relacionamento na comunidade escolar, tanto entre mestres e alunos como entre estes e os gestores, provocando um ambiente mais colaborativo. Foram propostas ações concretas decorrentes do ensino de ciências, ligadas a qualidade de vida e à melhoria do entorno habitado pelos alunos. O projeto contribui para a inclusão social, na medida em que favorece a diminuição da repetência e, conseqüentemente, da evasão escolar. Nossa intenção é colaborar para promover o alfabetismo científico-cultural, que significa um letramento que permita maior desenvolvimento cognitivo associado ao fomento a uma prática ética e, cada vez mais, cidadã.


Assuntos
Criança , Adolescente , Humanos , Avaliação Educacional/métodos , Ciência/educação , Ensino Fundamental e Médio , Brasil
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