Phytoplankton scenario and microcystin in water during extreme drought in semiarid tropical water supplies, Northeastern Brazil / Cenário de fitoplanctônico e microcistinas na água durante extrema estiagem em reservatórios tropical semiárido de abastecimento de água, nordeste do Brasil

The objective of this study was to characterize the limnological, microystin and phytoplankton community of five tropical eutrophic reservoirs located in the Brazilian northeastern semi-arid region, used for domestic use at the time of extreme drought and reduction of water volume. The study was conducted in July and August 2015, and an integrated sample of the water column was collected at three points near the dam in each reservoir. Analysis of limnological parameters, identification and quantification of phytoplankton, with emphasis on cyanobacteria were performed, as well as detection of microcystin by means of immunoassay (ELISA). The reservoirs presented ~ 90% water volume reduction. High turbidity and concentrations of nitrogen and phosphorus, as well as high cyanobacterial densities, revealed an increase in the eutrophic state for hypereutrophy. The total biovolume of phytoplankton and cyanobacterial density is high, plus an average increase in relation to previous studies of 350% and 150%, respectively. The density of cyanobacteria and microcystin concentration presented values ​​above acceptable levels for drinking water according to Brazilian legislation. A phytoplankton community was represented by 17 functional groups, including potentially toxic cyanobacteria species such as Planktothrix agardhii (S1), Microcystis aeruginosa (M), Anabaena planktonica e Anabaena spp. (H1), Cylindrospermopsis raciborskii (Sn). Our results confirm that conditions of extreme drought and reduction of the volume of the reservoirs influence the composition, biovolume of phytoplankton and water quality, but not the increase of total microcystin in the analysed, although above 1μg-1 registered a significant decrease of water quality in used for human consumption.(AU)

O objetivo deste trabalho foi caracterizar a comunidade limnológica, microistalina e fitoplanctônica de cinco reservatórios eutróficos tropicais localizados no semi-árido nordestino brasileiro, utilizados para uso doméstico no período de seca extrema e redução do volume de água. O estudo foi realizado em julho e agosto de 2015, e uma amostra integrada da coluna de água foi coletada em três pontos próximos à barragem em cada reservatório. Análises de parâmetros limnológicos, identificação e quantificação do fitoplâncton, com ênfase em cianobactérias, foram realizadas, assim como a detecção de microcistina por meio de imunoensaio (ELISA). Os reservatórios apresentaram ~ 90% de redução do volume de água. A alta turbidez e as concentrações de nitrogênio e fósforo, bem como as altas densidades de cianobactérias, revelaram um aumento no estado eutrófico da hipereutrofia. O biovolume total de fitoplâncton e densidade de cianobactérias é alto, além de um aumento médio em relação a estudos anteriores de 350% e 150%, respectivamente. A densidade de cianobactérias e a concentração de microcistina apresentaram valores acima dos níveis aceitáveis ​​para água de consumo, de acordo com a legislação brasileira. Uma comunidade fitoplanctônica foi representada por 17 grupos funcionais, incluindo espécies de cianobactérias potencialmente tóxicas, como Planktothrix agardhii (S1), Microcystis aeruginosa (M), Anabaena planktonica e Anabaena spp. (H1), Cylindrospermopsis raciborskii (Sn). Nossos resultados confirmam que condições de seca extrema e redução do volume dos reservatórios influenciam a composição, o biovolume de fitoplâncton e a qualidade da água, mas não o aumento do total de microcistina no analisado, embora acima de 1μg-1 tenha registrado uma diminuição significativa da qualidade da água usado para consumo humano.(AU)

Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs? / Microcistinas podem afetar a estrutura da comunidade zooplanctônica em reservatórios eutróficos tropicais?

Abstract The aim of our study was to assess whether cyanotoxins (microcystins) can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers). Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001), but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = 0.01; P > 0.01) with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001). The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass) do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers). These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.(AU)

Resumo Com o objetivo de avaliar se as cianotoxinas (microcistinas) podem afetar a composição da comunidade zooplanctônica, levando à dominância de formas microzooplanctônicas (protozoários e rotiferos), as variações nas concentrações de microcistina e a biomassa do zooplâncton foram analisadas em três reservatórios eutróficos na região semi-árida do nordeste brasileiro. A concentração de microcistinas na água esteve correlacionada com o biovolume de cianobactérias, indicando a contribuição de formas coloniais como Microcystis na produção de cianotoxinas. A nível de comunidade, a biomassa total do zooplâncton não apresentou correlacão com a concentração de microcistina (r2 = 0.00; P > 0.001), mas em uma análise a nível de populações, a biomassa de rotíferos e cladóceros apresentou uma fraca correlação positiva. Copépodos Cyclopoida, os quais são considerados relativamente ineficientes na ingestão de cianobactérias, estiveram negativamente correlacionados com a concentração de microcistinas (r2 = - 0.01; P > 0.01). Surpreendentemente, a biomassa de copépodos Calanoida foi positivamente correlacionada com a concentração de cianotoxinas (r2 = 0.44; P > 0.001). Os resultados indicam que mecanismos de controle alelopáticos (efeitos negativos da microcistina sobre o zooplâncton) parecem não afetar substancialmente a composição do mesozooplâncton, que apresentou uma alta e constante biomassa, quando comparada à biomassa do microzooplâncton (rotíferos). Esses resultados podem ser importantes para um melhor entendimento das interações tróficas entre o zooplâncton e cianobactérias, e do efeito potencial de compostos alelopáticos sobre o zooplâncton.(AU)

Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs?

Abstract The aim of our study was to assess whether cyanotoxins (microcystins) can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers). Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001), but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = 0.01; P > 0.01) with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001). The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass) do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers). These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.

Resumo Com o objetivo de avaliar se as cianotoxinas (microcistinas) podem afetar a composição da comunidade zooplanctônica, levando à dominância de formas microzooplanctônicas (protozoários e rotiferos), as variações nas concentrações de microcistina e a biomassa do zooplâncton foram analisadas em três reservatórios eutróficos na região semi-árida do nordeste brasileiro. A concentração de microcistinas na água esteve correlacionada com o biovolume de cianobactérias, indicando a contribuição de formas coloniais como Microcystis na produção de cianotoxinas. A nível de comunidade, a biomassa total do zooplâncton não apresentou correlacão com a concentração de microcistina (r2 = 0.00; P > 0.001), mas em uma análise a nível de populações, a biomassa de rotíferos e cladóceros apresentou uma fraca correlação positiva. Copépodos Cyclopoida, os quais são considerados relativamente ineficientes na ingestão de cianobactérias, estiveram negativamente correlacionados com a concentração de microcistinas (r2 = - 0.01; P > 0.01). Surpreendentemente, a biomassa de copépodos Calanoida foi positivamente correlacionada com a concentração de cianotoxinas (r2 = 0.44; P > 0.001). Os resultados indicam que mecanismos de controle alelopáticos (efeitos negativos da microcistina sobre o zooplâncton) parecem não afetar substancialmente a composição do mesozooplâncton, que apresentou uma alta e constante biomassa, quando comparada à biomassa do microzooplâncton (rotíferos). Esses resultados podem ser importantes para um melhor entendimento das interações tróficas entre o zooplâncton e cianobactérias, e do efeito potencial de compostos alelopáticos sobre o zooplâncton.

Antimycobacterial and cytotoxicity activity of microcystins

Background The present work aimed to evaluate the antimycobacterial activity and cytotoxicity of Microcystis aeruginosa toxins, the MC-LR variant and purified extract of [D-Leu1] microcystin-LR. Methods The antimicrobial activity of M. aeruginosa extract and microcystin was evaluated by resazurin microtiter assay against Mycobacterium tuberculosis, M. terrae, M. chelonae and M. kansasii. The cytotoxicity assay was performed by trypan blue exclusion against the HTC cell line. Results Antimicrobial activity was observed in the hexanic extract of M. aeruginosa (RST 9501 strain) against M. tuberculosis, including sensitive and resistant strains with minimal inhibitory concentrations (MIC) between 1.93 M and 0.06 M. The high activity of M. aeruginosa hexanic extract could be attributed to the major presence of the toxins MC-LR and [D-Leu1] MC-LR that showed activity at MIC between 53 and 0.42 M against tested mycobacterial strains. Even at the highest concentration tested, no toxicity of M. aeruginosa extracts was identified against HTC cells. Conclusions These preliminary results suggest that [D-Leu1] MC-LR is a promising candidate for the development of a new antimycobacterial agent.(AU)

Degradation of cyanotoxins (microcystin) in drinking water using photoelectrooxidation

p>The discharge of sewage and industrial effluents containing high concentrations of pollutants in water bodies increases eutrophication. Cyanobacteria, some of the organisms whose growth is promoted by high nutrient concentrations, are resistant and produce several types of toxins, known as cyanotoxins, highly harmful to human beings. Current water treatment systems for the public water supply are not efficient in degradation of toxins. Advanced oxidation processes (AOP) have been tested for the removal of cyanotoxins, and the results have been positive. This study examines the application of photoelectrooxidation in the degradation of cyanotoxins (microcystins). The performance of the oxidative processes involved was evaluated separately: Photocatalysis, Electrolysis and Photoelectrooxidation. Results showed that the electrical current and UV radiation were directly associated with toxin degradation. The PEO system is efficient in removing cyanotoxins, and the reduction rate reached 99%. The final concentration of toxin was less than 1 µg/L of microcystin in the treated solution. /p>

p>A descarga de esgotos e efluentes industriais contendo altas concentrações de poluentes nos corpos d'água aumenta a eutrofização. As cianobactérias, são organismos cujo crescimento é promovido por concentrações elevadas de nutrientes, são resistentes e produzem vários tipos de toxinas conhecidas, como cianotoxinas, altamente prejudiciais para os seres humanos. Os sistemas atuais de tratamento de água para o abastecimento público de água não são eficientes na degradação destas toxinas. Processos oxidativos avançados (POA) foram testados para a remoção de cianotoxinas, e os resultados têm sido positivos. Este estudo avalia o processo de fotoeletrooxidação (FEO) na degradação de cianotoxinas (microcistinas). Foi avaliado o desempenho dos processos envolvidos separadamente: fotocatalisis, eletrólise e fotoeletrooxidação. Os resultados mostram que a potencia da radiação UV e da corrente elétrica estão diretamente associados com a degradação de toxinas. O sistema de FEO é eficiente na remoção de cianotoxinas e a redução foi de 99%. A concentração final de toxina foi inferior a 1 g / L de microcistina na solução tratada. /p>

Biodegradation of [D-Leu1] microcystin-LR by a bacterium isolated from sediment of Patos Lagoon estuary, Brazil

Background Toxic cyanobacterial blooms are recurrent in Patos Lagoon, in southern Brazil. Among cyanotoxins, [D-Leu1] microcystin-LR is the predominant variant whose natural cycle involves water and sediment compartments. This study aimed to identify and isolate from sediment a bacterial strain capable of growing on [D-Leu1] microcystin-LR. Sediment and water samples were collected at two distinct aquatic spots: close to the Oceanographic Museum (P1), in Rio Grande City, and on São Lourenço Beach (P2), in São Lourenço do Sul City, southern Brazil. Methods [D-Leu1] microcystin-LR was isolated and purified from batch cultures of Microcystis aeruginosastrain RST9501. Samples of water and sediment from Rio Grande and São Lourenço do Sul were collected. Bacteria from the samples were allowed to grow in flasks containing solely [D-Leu1] microcystin-LR. This strain named DMSX was isolated on agar MSM with 8 g L1 glucose and further purified on a cyanotoxin basis growth. Microcystin concentration was obtained by using the ELISA immunoassay for microcystins whereas bacterial count was performed by epifluorescence microscopy. The genus Pseudomonas was identified by DNA techniques. Results Although several bacterial strains were isolated from the samples, only one, DMXS, was capable of growing on [D-Leu1] microcystin-LR. The phylogenetic analysis of the 16S rRNA gene from DMXS strain classified the organism as Pseudomonas aeruginosa. DMXS strain incubated with [D-Leu1] microcystin-LR lowered the amount of toxin from 1 g.L1 to 0.05 g.L1. Besides, an increase in the bacterial countfrom 71×105 bacteria.mL1 to 117×105 bacteria.mL1was observed along the incubation. Conclusions The use of bacteria isolated from sediment for technological applications to remove toxic compounds is viable. Studies have shown that sediment plays an important role as a source of bacteria capable of degrading cyanobacterial toxins. This is the first Brazilian report on a bacteriumof the genus Pseudomonasthat can degrade [D-Leu1] microcystin-LR, the most frequent microcystin variant in Brazilian freshwaters.(AU)

Biodegradation of [D-Leu1] microcystin-LR by a bacterium isolated from sediment of Patos Lagoon estuary, Brazil

Background Toxic cyanobacterial blooms are recurrent in Patos Lagoon, in southern Brazil. Among cyanotoxins, [D-Leu1] microcystin-LR is the predominant variant whose natural cycle involves water and sediment compartments. This study aimed to identify and isolate from sediment a bacterial strain capable of growing on [D-Leu1] microcystin-LR. Sediment and water samples were collected at two distinct aquatic spots: close to the Oceanographic Museum (P1), in Rio Grande City, and on São Lourenço Beach (P2), in São Lourenço do Sul City, southern Brazil. Methods [D-Leu1] microcystin-LR was isolated and purified from batch cultures of Microcystis aeruginosastrain RST9501. Samples of water and sediment from Rio Grande and São Lourenço do Sul were collected. Bacteria from the samples were allowed to grow in flasks containing solely [D-Leu1] microcystin-LR. This strain named DMSX was isolated on agar MSM with 8 g L1 glucose and further purified on a cyanotoxin basis growth. Microcystin concentration was obtained by using the ELISA immunoassay for microcystins whereas bacterial count was performed by epifluorescence microscopy. The genus Pseudomonas was identified by DNA techniques. Results Although several bacterial strains were isolated from the samples, only one, DMXS, was capable of growing on [D-Leu1] microcystin-LR. The phylogenetic analysis of the 16S rRNA gene from DMXS strain classified the organism as Pseudomonas aeruginosa. DMXS strain incubated with [D-Leu1] microcystin-LR lowered the amount of toxin from 1 g.L1 to 0.05 g.L1. Besides, an increase in the bacterial countfrom 71×105 bacteria.mL1 to 117×105 bacteria.mL1was observed along the incubation. Conclusions The use of bacteria isolated from sediment for technological applications to remove toxic compounds is viable. Studies have shown that sediment plays an important role as a source of bacteria capable of degrading cyanobacterial toxins. This is the first Brazilian report on a bacteriumof the genus Pseudomonasthat can degrade [D-Leu1] microcystin-LR, the most frequent microcystin variant in Brazilian freshwaters.

Degradation of cyanotoxins (microcystin) in drinking water using photoelectrooxidation / Degradação de cianotoxinas (microcistinas) em água potável aplicando fotoeletrooxidação

The discharge of sewage and industrial effluents containing high concentrations of pollutants in water bodies increases eutrophication. Cyanobacteria, some of the organisms whose growth is promoted by high nutrient concentrations, are resistant and produce several types of toxins, known as cyanotoxins, highly harmful to human beings. Current water treatment systems for the public water supply are not efficient in degradation of toxins. Advanced oxidation processes (AOP) have been tested for the removal of cyanotoxins, and the results have been positive. This study examines the application of photoelectrooxidation in the degradation of cyanotoxins (microcystins). The performance of the oxidative processes involved was evaluated separately: Photocatalysis, Electrolysis and Photoelectrooxidation. Results showed that the electrical current and UV radiation were directly associated with toxin degradation. The PEO system is efficient in removing cyanotoxins, and the reduction rate reached 99%. The final concentration of toxin was less than 1 µg/L of microcystin in the treated solution..(AU)

A descarga de esgotos e efluentes industriais contendo altas concentrações de poluentes nos corpos d'água aumenta a eutrofização. As cianobactérias, são organismos cujo crescimento é promovido por concentrações elevadas de nutrientes, são resistentes e produzem vários tipos de toxinas conhecidas, como cianotoxinas, altamente prejudiciais para os seres humanos. Os sistemas atuais de tratamento de água para o abastecimento público de água não são eficientes na degradação destas toxinas. Processos oxidativos avançados (POA) foram testados para a remoção de cianotoxinas, e os resultados têm sido positivos. Este estudo avalia o processo de fotoeletrooxidação (FEO) na degradação de cianotoxinas (microcistinas). Foi avaliado o desempenho dos processos envolvidos separadamente: fotocatalisis, eletrólise e fotoeletrooxidação. Os resultados mostram que a potencia da radiação UV e da corrente elétrica estão diretamente associados com a degradação de toxinas. O sistema de FEO é eficiente na remoção de cianotoxinas e a redução foi de 99%. A concentração final de toxina foi inferior a 1 g / L de microcistina na solução tratada.(AU)

Estudo da presença da toxina microcistina na água de reservatório deMundaú (Garanhuns-PE) pelas metodologias ELISA e CLAE / Study on the occurrence of microcystin toxin in water reservoir ofMundaú (Garanhuns-PE) by ELISA and HPLC methodologies

As cianobactérias são responsáveis pela produção de cianotoxinas que, uma vez acumuladas, podem causar sérios danos à saúde humana e animal. As microcistinas são o tipo mais comum de cianotoxinas e são promotoras de tumores hepáticos. O reservatório de Mundaú, localizado no município de Garanhuns-PE, foi o local escolhido por apresentar histórico de florações de cianobactérias produtoras de microcistinas. Neste trabalho foi investigada a presença de microcistinas em amostras de água bruta do reservatório do rio Mundaú utilizando-se as técnicas de Enzyme Linked Immunosorbent Assay (ELISA) e Cromatografia Líquida de Alta Eficiência (CLAE). Durante quinze meses consecutivos, as amostras de água foram coletadas em duplicata no ponto de captação deste manancial e analisadas por ambas metodologias ELISA e CLAE. A presença de microcistinas foi detectada em 100 % das amostras, confirmando-se a relevância do monitoramento de microcistinas em águas de abastecimento público, pois assim como o rio Mundaú, vários mananciais de Pernambuco apresentam florações de cianobactérias que podem ser tóxicas. Este trabalho deixou como legado a implantação da referida análise no Laboratório Central de Saúde Pública (LACEN-PE), e demonstrou sua importância como metodologia complementar à contagem das cianobactérias, para fornecer subsídios às ações preventivas de vigilância à saúde.(AU)

Cyanobacteria are responsible for the production of cyanotoxins, and once accumulated, it might cause serious harm to the human and animals health. Microcystins are the most common type of cyanotoxins and they cause liver tumor. The Mundaú reservoir, located in the municipality of Garanhuns-PE, was the selected site for presenting historical blooms of microcystins-producing cyanobacteria. This study analyzed the occurrence of microcystins in raw water samples from the Mundaú reservoir by using Enzyme Linked Immunosorbent Assay (ELISA) and High Performance Liquid Chromatography (HPLC) methodologies. During the consecutive fifteen months, water samples were collected in duplicate at the intake point of this water source, and they were analyzed by both ELISA and HPLC techniques. The presence of microcystins was detected in 100 % of analyzed samples, confirming the relevance of performing the microcystins monitoring in public water supplies. And as well as the Mundaú river, various water sources of Pernambuco show cyanobacterial blooms, which might be toxic. The techniques used in this study were implemented in the Central Laboratory of Public Health of Pernambuco (LACEN-PE), and they showed to be a relevant tools as a complementary methodology to the cyanobacteria counting assay for providing preventive subsidies to the health surveillance.(AU)

Phytotoxicity associated to microcystins: a review / Fitotocixidade associada às microcistinas: uma revisão

Microcystins (MC) are the most studied toxins of cyanobacteria since they are widely distributed and account for several cases of human and animal poisoning, being potent inhibitors of the serine/threonine protein phosphatases 1 (PP1) and 2A (PP2A). The phosphatases PP1 and PP2A are also present in plants, which may also suffer adverse effects due to the inhibition of these enzymes. In aquatic plants, biomass reduction is usually observed after absorption of cyanotoxins, which can bioaccumulate in its tissues. In terrestrial plants, the effects caused by microcystins vary from inhibition to stimulation as the individuals develop from seedling to adult, and include reduction of protein phosphatases 1 and 2A, oxidative stress, decreased photosynthetic activity and even cell apoptosis, as well as bioaccumulation in plant tissues. Thus, the irrigation of crop plants by water contaminated with microcystins is not only an economic problem but becomes a public health issue because of the possibility of food contamination, and this route of exposure requires careful monitoring by the responsible authorities.(AU)

Microcistinas (MC) são as toxinas de cianobactérias mais estudadas, uma vez que são amplamente distribuídas e responsáveis por vários casos de intoxicação humana e animal. São potentes inibidoras das proteínas fosfatases serina/treonina 1 (PP1) e 2A (PP2A). As fosfatases PP1 e PP2A também estão presentes em plantas, as quais podem sofrer efeitos adversos devido à inibição dessas enzimas. Em plantas aquáticas, a redução da biomassa é geralmente observada após absorção de cianotoxinas que podem bioacumular em seus tecidos. Em plantas terrestres, os efeitos causados pelas microcistinas variam de inibição ao estímulo, como no desenvolvimento de plântulas ao estádio adulto, e incluem a redução de proteínas fosfatases 1 e 2A, estresse oxidativo, diminuição da atividade fotossintética e até mesmo apoptose celular, bem como a bioacumulação em tecidos de plantas. Assim, a irrigação de plantas cultivadas com água contaminada com microcistina não é apenas um problema econômico, mas torna-se um problema de saúde pública, devido à possibilidade de contaminação dos alimento, sendo uma via de exposição que requer um monitoramento cuidadoso por parte das autoridades responsáveis.(AU)

Biochemical and genetic alterations in the freshwater neotropical fish Prochilodus lineatus after acute exposure to Microcystis aeruginosa

Microcystins are secondary metabolites produced by different species of cyanobacteria, such as Microcystis aeruginosa (MA). In this study, the biochemical and genetic effects of lyophilized MA were evaluated in the neotropical fish Prochilodus lineatus exposed to 1 or 2 mg L-1 lyophilized MA (treated group) or only water (control group) in static toxicity tests for 24 and 96 h. The gills and liver were used in the analysis of biotransformation enzymes and antioxidant defenses, blood and gill cells in genetic analysis and in brain and muscle it was determined the activity of acetylcholinesterase (AChE). The results showed the biotransformation pathway activation due to the increase in hepatic CYP1A and in branchial and hepatic glutathione S-transferase (GST). The antioxidant defense proved to be greatly affected by MA exposure leading to changes, both in gills and liver, in the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and in the content of tripeptide glutathione (GSH). Lipid peroxidation was not detected, but damage to DNA molecule was observed in blood cells. In conclusion, it can be state the lyophilized MA is able to promote changes in the biochemical and genetic parameters of P. lineatus.(AU)

As microcistinas são metabólitos secundários produzidos por diferentes espécies de cianobactérias, como a Microcystis aeruginosa (MA). Neste estudo, os efeitos bioquímicos e genéticos de liofilizado de MA foram avaliados para juvenis da espécie de peixe Neotropical Prochilodus lineatus expostos a 1 ou 2 mg L-1 de liofilizado de MA (grupo tratado) ou apenas à água (grupo controle), em testes de toxicidade estáticos, durante 24 e 96 h. As brânquias e o fígado foram usados para as análises das enzimas de biotransformação e defesas antioxidantes, células do sangue e das brânquias para análises genéticas e no cérebro e músculo foi determinada a atividade da acetilcolinesterase (AChE). Os resultados mostraram ativação da via de biotransformação devido ao aumento da atividade da CYP1A hepática e da atividade da glutationa S-transferase (GST) hepática e branquial. As defesas antioxidantes foram muito afetadas pela exposição a MA levando a alterações, tanto no fígado como nas brânquias, na atividade da superóxido dismutase (SOD), da catalase (CAT), da glutationa peroxidase (GPx), glutationa redutase (GR) e no conteúdo do tripeptídeo glutationa (GSH). Apesar dessas alterações a peroxidação lipídica não foi detectada em nenhum dos tecidos, mas danos na molécula de DNA foram observados nas células do sangue. Em conclusão, pode-se afirmar que o liofilizado de MA é capaz de promover alterações em parâmetros bioquímicos e genéticos de P. lineatus.(AU)

CRESCIMENTO E HISTOPATOLOGIA HEPÁTICA DE TILÁPIAS DO NILO ALIMENTADAS CONTINUAMENTE COM Microcystis aeruginosa LIOFILIZADA E L-CARNITINA DIETÉTICA EM CONDIÇÕES LABORATORIAIS

No presente estudo foi avaliado o efeito da adição da L-carnitina (LC) sobre o desempenho e histologia do fígado de juvenis de tilápia do Nilo submetidos a repetidas doses de microcistina (MCs). Para isso, células liofilizadas de cianobactérias (CIAN) Microcystis aeruginosa NPJL4 foram incluídas (0,3%) em dietas sem L-carnitina (CIAN), com 1 g de L-carnitina kg-1 (CIAN+LC-1), 2 g de L-carnitina kg-1 (CIAN+LC-2) e sem CIAN e LC (CONT). Juvenis de tilápia do Nilo (±4,8 g de peso inicial) foram distribuídos em aquários de 60L (20 peixes/aquário). As dietas foram fornecidas durante 28 dias em três refeições diárias a taxa de 5% da biomassa de modo a fornecer 1,2 µg de microcistinas g-1 de peixe/dia. Nos dias 0, 3, 7, 14, 21 e 28 os fígados foram coletados para análises histológicas. A sobrevivência e o desempenho zootécnico não foram influenciados (p>0,05) pelos tratamentos. As principais lesões hepáticas induzidas pela ingestão de MCs foi a perda da coesão celular e necrose de hepatócitos, megalocitose e a perda da coesão celular pancreática. Não foi possível verificar nenhum efeito protetor significativo da L-carnitina em tilápias do Nilo ingerindo MCs repetidamente. A espécie demonstrou alta resistência a ingestão contínua de microcistinas por 28 dias.

The aim of this study was to evaluate the effect of the addition of L-carnitine (LC) on the performance and histology of juvenile liver of Nile tilapia subjected to repeated doses of microcystins (MCs). To this end, lyophilized cells of cyanobacteria (CIAN) Microcystis aeruginosa strain NPJL-4 were included (3.3%) in diets without L-carnitine (CIAN), 1 g Lcarnitine kg-1 (CIAN+LC-1), 2 g of L-carnitine kg-1 (CIAN+LC-2) and without CIAN and LC (CONT). Juvenile Nile tilapia (± 4.8 g initial weight) were distributed in 60L tanks (20 fish / aquarium). The diets were fed for 28 days in three meals a rate of 5% of the biomass so as to provide 1.2 ug MC-LR, g-1/fish/day. On days 0, 3, 7, 14, 21 and 28 samples of liver were collected for histological analysis. The survival and growth performance were not affected (p>0.05) by treatments. The foremost liver injury induced by MC intake was disorganization and necrosis of hepatocytes and pancreatic megalocytosis clutter. We could not find any significant protective effect of L-carnitine in Nile tilapia eating MCs repeatedly. The species showed high resistance to continuous intake of microcystins for 28 days.

Diversity of microcystin-producing genotypes in Brazilian strains of Microcystis (Cyanobacteria)

Microcystis Kützing ex Lemmermann is among the genera of cyanobacteria often associated to toxic blooms with the release of microcystins. A gene cluster codes for microcystin synthetases, which are involved in the biosynthesis of this toxin. The aim of the present study was to investigate the genetic diversity of the mcyB gene, specifically the B1 module, in Brazilian strains of Microcystis spp. and its microcystin variants. Broad genetic diversity was revealed in this region. From the phylogenetic analysis, three clusters were obtained that were not related to the geographic origin or morphospecies of the strains, nor with the variant of the microcystin produced. A group of strains that did not produce microcystins was found, despite the presence of the mcyB1 fragment. Eight microcystin isoforms were detected: MC-LR, [D-Asp³]-MC-LR, [Asp³]-MC-LR, MC-RR, [Dha7]-MC-LR, MC-LF, MC-LW and [D-Asp³, EtAdda5]-MC-LH, the latter of which is described for the first time in Brazil. Moreover, five other variants were not identified and indicate being new.

Microcystis Kützing ex Lemmermann é dos gêneros de cianobactérias, frequentemente relacionados às florações tóxicas com a liberação de microcistinas. Um agrupamento de genes codifica as sintetases de microscistinas, as quais estão envolvidas na biossíntese desta toxina. O objetivo deste estudo foi investigar a diversidade genética do gene mcyB, especificamente o módulo B1, de linhagens brasileiras de Microcystis spp. e suas variantes de microcistinas. Uma ampla diversidade genética foi revelada nesta região. A partir da análise filogenética, três agrupamentos foram obtidos, os quais não se relacionaram com a origem geográfica ou com a morfoespécie das linhagens e nem tão pouco com a variante de microcistina produzida. Foi encontrado um grupo de linhagens que não produziu microcistinas, apesar da presença do fragmento mcyB1. Oito variantes de microcistinas foram detectadas: MC-LR, [D-Asp³]-MC-LR, [Asp³]-MC-LR, MC-RR, [Dha7]-MC-LR, MC-LF e MC-LW e [D-Asp³, EtAdda5]-MC-LH, sendo esta última descrita pela primeira vez no Brasil. Além destas, cinco outras variantes não foram identificadas com indicativos de serem novas.

Diversity of microcystin-producing genotypes in Brazilian strains of Microcystis (Cyanobacteria) / Diversidade de genótipos produtores de microcistinas em linhagens brasileiras de Microcystis (Cyanobacteria)

Microcystis Kützing ex Lemmermann is among the genera of cyanobacteria often associated to toxic blooms with the release of microcystins. A gene cluster codes for microcystin synthetases, which are involved in the biosynthesis of this toxin. The aim of the present study was to investigate the genetic diversity of the mcyB gene, specifically the B1 module, in Brazilian strains of Microcystis spp. and its microcystin variants. Broad genetic diversity was revealed in this region. From the phylogenetic analysis, three clusters were obtained that were not related to the geographic origin or morphospecies of the strains, nor with the variant of the microcystin produced. A group of strains that did not produce microcystins was found, despite the presence of the mcyB1 fragment. Eight microcystin isoforms were detected: MC-LR, [D-Asp³]-MC-LR, [Asp³]-MC-LR, MC-RR, [Dha7]-MC-LR, MC-LF, MC-LW and [D-Asp³, EtAdda5]-MC-LH, the latter of which is described for the first time in Brazil. Moreover, five other variants were not identified and indicate being new.

Microcystis Kützing ex Lemmermann é dos gêneros de cianobactérias, frequentemente relacionados às florações tóxicas com a liberação de microcistinas. Um agrupamento de genes codifica as sintetases de microscistinas, as quais estão envolvidas na biossíntese desta toxina. O objetivo deste estudo foi investigar a diversidade genética do gene mcyB, especificamente o módulo B1, de linhagens brasileiras de Microcystis spp. e suas variantes de microcistinas. Uma ampla diversidade genética foi revelada nesta região. A partir da análise filogenética, três agrupamentos foram obtidos, os quais não se relacionaram com a origem geográfica ou com a morfoespécie das linhagens e nem tão pouco com a variante de microcistina produzida. Foi encontrado um grupo de linhagens que não produziu microcistinas, apesar da presença do fragmento mcyB1. Oito variantes de microcistinas foram detectadas: MC-LR, [D-Asp³]-MC-LR, [Asp³]-MC-LR, MC-RR, [Dha7]-MC-LR, MC-LF e MC-LW e [D-Asp³, EtAdda5]-MC-LH, sendo esta última descrita pela primeira vez no Brasil. Além destas, cinco outras variantes não foram identificadas com indicativos de serem novas.

Toxic cyanobacteria in reservoirs in northeastern Brazil: detection using a molecular method / Cianobactérias tóxicas em reservatórios do nordeste do Brasil: detecção utilizando método molecular

Cyanobacterial blooms are a frequent occurrence in northeastern Brazil and constitute a serious public health problem. Using the polymerase chain reaction (PCR) method, eleven environmental samples with cyanobacteria from seven reservoirs were used to determine the presence of the gene involved in microcystin biosynthesis (mcyB). Two sets of oligonucleotide primers were designed from the sequencing of Brazilian populations of microcystin producing cyanobacteria (mcyB-F/R and mcyB-F/R-A). The presence of the mcyB gene involved in microcystin biosynthesis was found in all samples, indicating the potential of this gene for producing the toxin. The PCR method proved sensitive and appropriate for the detection of potential producers of microcystins in environmental samples. Its ability to reveal potentially toxic cyanobacteria demonstrates that it can be a valuable tool in the monitoring of blooms.

Florações de cianobactérias são frequentes no nordeste do Brasil, constituindo um sério problema de Saúde Pública. Através da utilização da técnica de PCR, onze amostras ambientais com cianobactérias provenientes de sete reservatórios foram utilizadas para verificar a presença de um dos genes envolvido na biossíntese de microcistina (mcyB). Para isso foram utilizados dois conjuntos de oligonucleotídeos primers (mcyB-F/R e mcyB-F/R-A) desenhados a partir de sequências de populações brasileiras de Microcystis produtoras de microcistina. A presença do gene mcyB foi verificada em todas as amostras analisadas, indicando a capacidade de produzir esta toxina. O método de PCR apresentou-se sensível e apropriado para a detecção de potenciais produtores de microcistinas em amostras ambientais. Sua habilidade em detectar genótipos indicadores de produção de microcistina nos reservatórios investigados sugere que este método pode auxiliar no monitoramento de florações.

Toxic cyanobacteria in reservoirs in northeastern Brazil: detection using a molecular method

Cyanobacterial blooms are a frequent occurrence in northeastern Brazil and constitute a serious public health problem. Using the polymerase chain reaction (PCR) method, eleven environmental samples with cyanobacteria from seven reservoirs were used to determine the presence of the gene involved in microcystin biosynthesis (mcyB). Two sets of oligonucleotide primers were designed from the sequencing of Brazilian populations of microcystin producing cyanobacteria (mcyB-F/R and mcyB-F/R-A). The presence of the mcyB gene involved in microcystin biosynthesis was found in all samples, indicating the potential of this gene for producing the toxin. The PCR method proved sensitive and appropriate for the detection of potential producers of microcystins in environmental samples. Its ability to reveal potentially toxic cyanobacteria demonstrates that it can be a valuable tool in the monitoring of blooms.

Florações de cianobactérias são frequentes no nordeste do Brasil, constituindo um sério problema de Saúde Pública. Através da utilização da técnica de PCR, onze amostras ambientais com cianobactérias provenientes de sete reservatórios foram utilizadas para verificar a presença de um dos genes envolvido na biossíntese de microcistina (mcyB). Para isso foram utilizados dois conjuntos de oligonucleotídeos primers (mcyB-F/R e mcyB-F/R-A) desenhados a partir de sequências de populações brasileiras de Microcystis produtoras de microcistina. A presença do gene mcyB foi verificada em todas as amostras analisadas, indicando a capacidade de produzir esta toxina. O método de PCR apresentou-se sensível e apropriado para a detecção de potenciais produtores de microcistinas em amostras ambientais. Sua habilidade em detectar genótipos indicadores de produção de microcistina nos reservatórios investigados sugere que este método pode auxiliar no monitoramento de florações.

Influência de fatores climatológicos na ocorrência de microcistina / Influence of climatic factors on the occurrence of microcystin

As toxinas de cianobactérias têm sido um problema de saúde pública pela capacidade de contaminar águas dos reservatórios. Microcistinas (MCs) são compostos fortemente hepatotóxicos produzidos por diferentes cianobactérias, sendo a mais comum a Microcystis aeruginosa. Este estudo, realizado em 2005, pesquisou a ocorrência de MCs na região noroeste do Estado de São Paulo, bem como sua relação com a temperatura e o índice pluviométrico. A pesquisa de MCs nas amostras de água foi realizada por meio de ELISA (kitcomercial), empregando-se anticorpo monoclonal. As concentrações de MCs mostraram variação temporal e foram relativamente menores durante as altas temperaturas. Apesar da contaminação detectada não ser considerada alta, recomenda-se a realização de constante monitoramento. (AU)

Cyanobacteria toxins have been a public health problem, due to the ability incontaminating waters ofreservoirs. Microcystins (MCs) are strongly hepatotoxic produced by various cyanobacteria, notablyMicrocystis aeruginosa. The present investigation, conducted in 2005, aimed at studying the occurrenceof MCs in the northwestern region of São Paulo State, and also its relationship with temperature and rainfalls, which favor the development of cyanobacteria. The MCs were determined in water samples by meansof commercial ELISA kit using a monoclonal antibody. Concentrations of MCs showed temporal variationand being relatively lower during the high temperatures. In spite of the contamination has not been high,a constant monitoring is recommended.(AU)

Cianobacterial bloom and animal mass mortality in a reservoir from Central Argentina / Florescimento de cianobactérias e mortalidade em massa de animais em um reservatório da Argentina Central

Piedras Moras reservoir (32° 10'27" S and 64° 16' 29" W; 832 ha), integrates a series of artificial lakes belonging to the Rio Tercero basin (Córdoba, Argentina). During March 2009 an algal bloom occurred, coinciding with several animal species mortality, mainly wild birds. The goal of this work was to establish the trophic status of the reservoir in relation to that mortality. Variables were evaluated in situ (temperature and water transparency) and samples were taken in order to identify algal species, Chl-a concentration (spectrophotometry) and toxins - total microcystines- (inmuno-enzymatic assay, ELISA). Histopathology studies were made on Fulica sp. A strong heterogenity in water transparency was observed, and "patches" of Potamogeton berteroanus distributed all along the lake, with Secchi disk minimal and medium values of 0.15 and 0.94 m. Chl-a concentration oscillated from 35.7 to 320.9 mg.m-3. Predominant phytoplankton species were Anabaena spiroides and Microcystis aeruginosa (Cyanophyceae). Water temperature was 27.8 °C (±0.88). Maximal value of total microcystine concentration was 0.23 μg.L-1. Chl-a concentration at the moment when mass mortality occurred (2.022 mg.m-3), and histopathological observations, strongly suggest that the animals' death was due to cianotoxins.

O reservatório de Piedras Moras (32° 10'27" S e 64° 16' 29" W; 832 ha) faz parte de uma série de lagos artificiais que estão localizados na bacia do rio Tercero (Córdoba, Argentina). Durante março de 2009, ocorreu um florescimento maciço de cianobactérias que resultou na morte de muitas espécies de animais, especialmente aves aquáticas silvestres. O objetivo deste trabalho foi o de estabelecer o estado trófico do reservatório em função desta mortalidade. As variáveis foram avaliadas in situ (temperatura e transparência da água). Foram coletadas amostras para analisar as espécies de algas encontradas nos florescimentos. Foram determinados chl-a (espectrofotometria) e toxinas (microcistinas totais - ensaio imunoenzimático ELISA). Estudos histopalógicos foram realizados em Fulica sp. Uma grande heterogeneidade em transparência de água foi observada e agrupamentos de Potamogeton berteroanus estavam distribuídos em todo o reservatório com valores mínimos e médios do disco de Secchi de 0,15 a 0,54 m. Concentrações de chl-a oscilaram de 35,7 a 320,9 mg.m-3. As espécies fitoplanctônicas dominantes identificadas foram Anabaena spiroides e Microcystis aeruginosa (Cyanophyceae). A temperatura da água foi de 27,8 °C (±0.88). O valor máximo de concentração de microcistinas foi de 0,23 µg.L-1. A concentração de chl-a, quando ocorreu a mortalidade em massa (2,022 mg.m-3), e as lesões histopatológicas indicam que a mortalidade de animais foi devida a cianotoxinas.

Screening the toxicity and toxin content of blooms of the cyanobacterium Trichodesmium erythraeum (Ehrenberg) in northeast Brasil

Blooms of the cyanobacterium Trichodesmium occur in massive colored patches over large areas of tropical and subtropical oceans. Recently, the interest in such events has increased given their role in major nitrogen and carbon dioxide oceanic fluxes. Trichodesmium occurs all along the Brazilian coast and patches frequently migrate towards the coast. In this paper we screen the toxicity and toxin content of Trichodesmium blooms off the coast of Bahia state. Four samples, collected from February to April 2007, were analyzed. Organisms were identified and assessed for toxicity by means of several methods. Analogues of microcystins, cylindrospermopsins and saxitoxins were analyzed using HPLC. Microcystins were also assayed through ELISA. Results showed dominance of T. erythraeum, which makes up as much as 99% of cell counts. Other organisms found in smaller quantities include the dinoflagellates Prorocentrum minimum and P. rhathymum. Extracts from all samples delayed or interrupted sea urchin larval development, but presented no acute toxicity during a mouse bioassay. Saxitoxin congeners and microcystins were present at low concentrations in all samples, occurrences that had not previously been reported in the literature. Despite our finding of saxitoxin analogues and microcystins in Trichodesmium blooms, these toxins do not represent a potential harm to human health by primary contact. We conclude, based on our results and those reported in the recent literature, which differ from results published in 1963, that although toxins are present, there is no evidence that T. erythraeum blooms represent a threat to humans.

Screening the toxicity and toxin content of blooms of the cyanobacterium Trichodesmium erythraeum (Ehrenberg) in northeast Brasil

Blooms of the cyanobacterium Trichodesmium occur in massive colored patches over large areas of tropical and subtropical oceans. Recently, the interest in such events has increased given their role in major nitrogen and carbon dioxide oceanic fluxes. Trichodesmium occurs all along the Brazilian coast and patches frequently migrate towards the coast. In this paper we screen the toxicity and toxin content of Trichodesmium blooms off the coast of Bahia state. Four samples, collected from February to April 2007, were analyzed. Organisms were identified and assessed for toxicity by means of several methods. Analogues of microcystins, cylindrospermopsins and saxitoxins were analyzed using HPLC. Microcystins were also assayed through ELISA. Results showed dominance of T. erythraeum, which makes up as much as 99% of cell counts. Other organisms found in smaller quantities include the dinoflagellates Prorocentrum minimum and P. rhathymum. Extracts from all samples delayed or interrupted sea urchin larval development, but presented no acute toxicity during a mouse bioassay. Saxitoxin congeners and microcystins were present at low concentrations in all samples, occurrences that had not previously been reported in the literature. Despite our finding of saxitoxin analogues and microcystins in Trichodesmium blooms, these toxins do not represent a potential harm to human health by primary contact. We conclude, based on our results and those reported in the recent literature, which differ from results published in 1963, that although toxins are present, there is no evidence that T. erythraeum blooms represent a threat to humans.