Algal blooms are a common phenomenon in lakes and seas in and around Sweden and poses a problem when found in a drinking water source. Some cyanobacteria can produce toxins which can be with a health problem. To get a safe drinking water it is necessary to be able to remove the toxins from the incoming water. This report has gathered information on cyanobacteria, cyanotoxins and conditions in the water source. Further investigation in two water sources, Bondsjön and Långsjön in Härnösand, have been made as well as a literature review regarding water treatment methods that are effective against cyanotoxins. The results from the lake investigation showed that there was almost no cyanobacteria present in the water in August 2018. Temperature- and water transparency analysis showed that the position of the intake of water to the water treatment plant is placed at a depth that may favour growth of cyanobacteria. A relocation of the intake would probably get a better quality of water regarding risk of cyanobacteria content in to the water treatment plant. The water treatment methods that would be recommended to remove cyanotoxins from the incoming water is pulverised activated carbon (PAC), granular activated carbon (GAC) and membrane filters in the form of nanofilters (NF). PAC is recommended for sporadic use, only when there is cyanotoxins in the water which will require a high control of the incoming water. GAC is recommended as a constant removal technique which will not require the extra control of the incoming water, however it is more sensitive for a high concentration of DOC in the water. NF is also recommended as a constant removal technique and which cross-flow technique is implemented to avoid accumulation of material on the filter surface.

Submitted by Bruna Buch (bruna.buch@gmail.com) on 2019-01-31T14:18:48Z No. of bitstreams: 1 BrunaBuch_Tese.pdf: 6059154 bytes, checksum: ab596bb37969e3a6ac3aea0557b5363e (MD5) / Rejected by Elza Mitiko Sato null (elzasato@ibilce.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo: Problema 01) Solicitamos que corrija o ano descrita na capa para 2019, o ano de entrega da dissertação na Seção Técnica de Pós-Graduação Problema 02) Segundo a Portaria nº 206, de 4 de setembro de 2018, todos os trabalhos que tiveram financiamento CAPES deve constar nos agradecimentos a expressão: "O presente trabalho foi realizado com apoio da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Código de Financiamento 001 Agradecemos a compreensão. on 2019-01-31T16:28:27Z (GMT) / Submitted by Bruna Buch (bruna.buch@gmail.com) on 2019-01-31T16:59:59Z No. of bitstreams: 1 BrunaBuchTese.pdf: 6058711 bytes, checksum: 91a5b502646692883f387f5ae5a634f6 (MD5) / Approved for entry into archive by Elza Mitiko Sato null (elzasato@ibilce.unesp.br) on 2019-01-31T17:24:13Z (GMT) No. of bitstreams: 1 buch_b_dr_sjrp.pdf: 6058711 bytes, checksum: 91a5b502646692883f387f5ae5a634f6 (MD5) / Made available in DSpace on 2019-01-31T17:24:13Z (GMT). No. of bitstreams: 1 buch_b_dr_sjrp.pdf: 6058711 bytes, checksum: 91a5b502646692883f387f5ae5a634f6 (MD5) Previous issue date: 2018-12-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As cianobactérias são importantes componentes das comunidades aquáticas em diversos ecossistemas, graças a longa história evolutiva do grupo que desenvolveu diversas adaptações fisiológicas e citológicas que permitiram a sua dominância ao redor do globo. As cianobactérias são também os bactérias fotossintetizantes com a morfologia mais diversificada e, embora essa qualidade tenha sido extensivamente utilizada pelos cientistas para a delimitação dos táxons e reconstrução da história evolutiva, vem perdendo cada vez mais espaço para o uso de marcadores moleculares, os quais são capazes de inferir relações filogenéticas mais robustas e que mais proximamente refletem o percurso evolutivo traçado por esses microrganismos. Desse modo, o objetivo da realização deste estudo foi caracterizar taxonomicamente populações de cianobactérias bentônicas de ambientes lênticos da região noroeste do estado de São Paulo, utilizando uma abordagem polifásica, por meio do uso do gene rRNA 16S e da estrutura secundária do ITS 16S-23S, além de considerar aspectos morfológicos e ecológicos. Como resultado deste trabalho, 41 populações de cianobactérias bentônicas foram avaliadas, sendo alocadas em 15 gêneros distribuídos em 11 famílias e cinco ordens. A ordem Oscillatoriales foi a mais representativa entre as populações estudadas (68,3%, 28 populações), seguida pela ordem Synechococcales (19,5%, 8 populações). A análise filogenética do gene RNAr 16S foi capaz de revelar a presença de táxons crípticos, que embora apresentem morfologia correspondente com táxons já descritos, formaram clados separados, indicando se tratarem de táxons ainda não conhecidos, e esse foi o caso de 13 populações aqui estudadas. Parte dos táxons crípticos foi trabalhada em maior profundidade, resultando em três manuscritos apresentados na forma de capítulos que correspondem à descrição dos novos gêneros e espécies Koinonema pervagatum (Capítulo III) e Blennothricopsis periphytica (Capítulo IV), além da descrição de três novas espécies para o gênero Phormidium (Capítulo V), com o registro da primeira espécie bentônica produtora de microcistina para o estado de São Paulo. Embora a prospecção dos genótipos tóxicos, utilizando marcadores específicos para os genes mcyE e sxtA responsáveis pela síntese de microcistinas e saxitoxinas, respectivamente, tenha revelado apenas uma linhagem tóxica, esse resultado é positivo do ponto de vista de impactos relacionados à presença de cianobactérias em corpos d’água para uso público. Entretanto, mostra a importância dos estudos de prospecção de toxinas em cianobactérias bentônicas no Brasil, ainda pouco explorados. / Cyanobacteria are important components of aquatic communities in different ecosystems, thanks to its long evolutionary history that provided several physiological and ecological adaptations, allowing them to spread around the globe. Cyanobacteria are also the most morpological diversified photossintetic bacterial group and, despite many taxonomists have extensively used this character to delimit taxa and to reconstruct their evolutionary history, it has been losing its prominence to molecular markers, which are most suited to infer robust phylogenetic relationships that properly reflect the evolutionary path followed by these organisms. Therefore, the aim of the study was to taxonomically characterize benthic cyanobacterial populations in lentic habitats from the Northwest region of São Paulo state, using a polyphasic approach, through the phylogenetic analysis of the 16S rRNA gene and the 16S 23S ITS secondary structure, aside from morphological and ecological aspects. As result, 41 benthic cyanobacterial populations were evaluated and assigned to 15 genera distributed in 11 families and five orders. The Oscillatoriales order was the most representative among all (69.3%, 28 populations), followed by the Synechococcales (19.5%, eight populations). The 16S rRNA phylogenetic analysis revealed the presence of cryptotaxa, which, despite morphologically ressembling previously described taxa, formed separated clades, suggesting not yet acknowledged taxa. That was the case of 13 populations studied. Some of these cryptotaxa were deeper evaluated in three manuscripts presented here as chapters and described as the new genera and species Koinonema pervagatum (Chapter III) and Blennothricopsis periphytica (Chapter IV), the description of three new species from the Phormidium genus (Chapter V) and the first record of a benthic microcystin producing cyanobacteria in the São Paulo state. Although the toxic genotypes prospection using specific molecular markers for the mcyE and sxtA genes, responsible for microcystin and saxitoxin production, respectively, revealed only one toxic strain, it demonstrates a positive result regarding the impact caused by toxic cyanobacterial strains in waters for public use worldwide. However, it highlights the importance of studies on potentially toxic benthic cyanobacterial communities, still little explored in Brazil.

Nodularia spumigena is an estuarine cyanobacteria that produces the toxin nodularin. This toxic cyanobacteria is known to have caused death to domestic and wild animals and is recognised as dangerous to human health. N. spumigena causes harmful algal blooms in many parts of the world including Australia. The toxic solutes of N. spumigena are potentially dangerous when contact is made to contaminated water bodies or is ingested by primary consumers. In Australia blooms of N. spumigena are common in the Gippsland Lakes in South-eastern Victoria and cause socio - economic hardships to the local communities. This PhD investigates the toxic effects of N. spumigena and its solutes to a range of aquatic life. A method known as SPME - HPLC showed promise in environmental monitoring of N. spumigena toxins by measuring nodularin from water samples. Other research presented study into the lethal and sublethal effects of on an extract from N. spumigena to aquatic fauna. Resu lts showed the N. spumigena extract was not lethal to many aquatic fauna although zooplankton from the Gippsland Lakes showed mortality at environmental relevant levels. Biochemical studies focusing on animal detoxification and antioxidation enzymes and DNA integrity showed sublethal effects to the N. spumigena extract. Results presented in this thesis show that an extract of N. spumigena elicited detoxification and antioxidation responses in animals tested. Furthermore, the use of the COMET assay showed increased damage to DNA of animals tested. Results also showed that different organs in animals tested responded differently to the aqueous extract, suggesting mode of uptake maybe important in toxicosis. Further, feeding studies with N. spumigena help elucidate mode of uptake using enzyme response biomarkers. The overall results of this research provided an assessment of the toxic affects of N. spumigena on aquatic fauna with special reference to the Gippsland Lakes, Victoria, Australia.

Anatoxin-a (ANTX) is a neurotoxin produced by several freshwater cyanobacteria and has been implicated in the death of livestock and domestic animals from consumption of tainted surface waters. ANTX is unstable under normal conditions and is somewhat problematic to extract and study. Accelerated solvent extraction (ASE) combined with liquid chromatography-mass spectrometry (LC/MS) was used to develop an efficient extraction and analytical method for both ANTX and the more commonly encountered hepatotoxic microcystins produced by cyanobacteria. The effects of nitrogen supply on the cellular production and release of ANTX was investigated in Aphanizomenon issatschenkoi (Ussaczew) Proschkina-Lavrenko (Nostocales). In contrast to the predictions of the carbonnutrient balance hypothesis, the maximum production was observed under moderate N stress. In addition, steady state fugacity-based models were employed to investigate ANTX’s distribution and fate in freshwater ecosytems. ANTX was not found to be very persistent in aquatic ecosystems and did not appear to bioaccumulate in fish, at least not from the dissolved phase.

Certain types of cyanobacteria have the potential to produce toxins including microcystin, a hepatotoxin. Toxic cyanobacterial blooms are becoming increasingly common worldwide. They are a concern in the Great Lakes and surrounding waters. In this study, Lake Ontario’s Bay of Quinte, Lake Erie’s Maumee Bay, and three reservoirs along the Grand River were studied. Environmental variables, cyanobacterial biomass inferred from the Fluoroprobe, and microcystin concentrations were measured. In 2005 the three reservoirs, Belwood Lake, Conestogo Lake, and Guelph Lake were sampled every two weeks from July to September. Belwood Lake was also sampled in October when a cyanobacterial bloom occurred. In 2006 the Bay of Quinte was sampled twice, in July and September, and Maumee Bay was sampled twice, in June and August. Physical variables measured included water transparency and temperature. All species of nitrogen (N) and phosphorus (P) were measured, along with extracted chlorophyll a and particulate carbon (C), N, and P. The distribution of chlorophyll and major algal groups throughout the water column was profiled in situ using a spectral fluorometer (Fluoroprobe).Variable fluorescence of phytoplankton was assessed using Pulse Amplitude Modulated (PAM) fluorometry to measure photosynthetic parameters. Phytoplankton counts were performed on selected samples from the Bay of Quinte and Maumee Bay. Total and dissolved microcystin were measured using the protein phosphatase inhibition assay (PPIA). PPIA was chosen over alternative detection methods because it is a functional assay that measures the level of microcystin in a sample via the amount of protein phosphatase inhibition that it exerts. This yields ecologically relevant data as protein phosphatase inhibition is the main mode of microcystin toxicity. The PPIA formulation used in our lab was based on variations in the literature that use unconcentrated water samples directly in the assay. The assay was optimized to employ both a higher and lower standard curve through the use of two enzyme concentrations. The lower enzyme concentration allowed the method detection limit to be decreased to 0.05 µg/L to accommodate our low-microcystin samples. In the Bay of Quinte, microcystin levels were higher in July 2006 (total mean=2.25 μg/L ) than in September 2006 (total mean=0.58 μg/L). In July a cyanobacterial bloom consisting of 97% Microcystis spp. was present. In September 83% of the cyanobacterial biomass was composed of Anabaena spiroides and only 8% was Microcystis spp. In the Bay of Quinte elevated microcystin concentrations were associated with higher soluble reactive P levels, lower seston C:P molar ratios, and lower total N. In Maumee Bay microcystin levels were higher in August 2006 (total mean= 4.45 μg/L) than they were in June 2006 (<0.05 μg/L). In August a cyanobacterial bloom consisting of 22% Microcystis spp. and 48% Aphanizomenon flos-aquae was observed. Higher microcystin concentrations in Maumee Bay were associated with decreased total N: total P molar ratios, increased total P, and decreased water transparency as measured by Secchi depth. Belwood Lake had the highest microcystin levels of the three reservoirs but only once exceeded the recommended World Health Organization concentration of 1.0 μg/L. Belwood Lake’s largest cyanobacterial bloom in October 2005 was accompanied by relatively low microcystin levels (<0.2 μg/L). Conestogo and Guelph lakes always had microcystin levels below 0.2 μg/L and 0.6 μg/L, respectively. In the Grand River reservoirs, increased microcystin concentrations were associated with higher chlorophyll a, higher light attenuation coefficients, lower total N, lower total N: total P molar ratios, higher C:P molar ratios, lower nitrate, higher cyanobacterial biomass, and higher total P. When data from the Bay of Quinte, Maumee Bay, and Grand River reservoirs were pooled, total microcystin had the most significant positive correlation with total P. Total microcystin and water temperature also had a significant positive correlation.

Certain types of cyanobacteria have the potential to produce toxins including microcystin, a hepatotoxin. Toxic cyanobacterial blooms are becoming increasingly common worldwide. They are a concern in the Great Lakes and surrounding waters. In this study, Lake Ontario’s Bay of Quinte, Lake Erie’s Maumee Bay, and three reservoirs along the Grand River were studied. Environmental variables, cyanobacterial biomass inferred from the Fluoroprobe, and microcystin concentrations were measured. In 2005 the three reservoirs, Belwood Lake, Conestogo Lake, and Guelph Lake were sampled every two weeks from July to September. Belwood Lake was also sampled in October when a cyanobacterial bloom occurred. In 2006 the Bay of Quinte was sampled twice, in July and September, and Maumee Bay was sampled twice, in June and August. Physical variables measured included water transparency and temperature. All species of nitrogen (N) and phosphorus (P) were measured, along with extracted chlorophyll a and particulate carbon (C), N, and P. The distribution of chlorophyll and major algal groups throughout the water column was profiled in situ using a spectral fluorometer (Fluoroprobe).Variable fluorescence of phytoplankton was assessed using Pulse Amplitude Modulated (PAM) fluorometry to measure photosynthetic parameters. Phytoplankton counts were performed on selected samples from the Bay of Quinte and Maumee Bay. Total and dissolved microcystin were measured using the protein phosphatase inhibition assay (PPIA). PPIA was chosen over alternative detection methods because it is a functional assay that measures the level of microcystin in a sample via the amount of protein phosphatase inhibition that it exerts. This yields ecologically relevant data as protein phosphatase inhibition is the main mode of microcystin toxicity. The PPIA formulation used in our lab was based on variations in the literature that use unconcentrated water samples directly in the assay. The assay was optimized to employ both a higher and lower standard curve through the use of two enzyme concentrations. The lower enzyme concentration allowed the method detection limit to be decreased to 0.05 µg/L to accommodate our low-microcystin samples. In the Bay of Quinte, microcystin levels were higher in July 2006 (total mean=2.25 μg/L ) than in September 2006 (total mean=0.58 μg/L). In July a cyanobacterial bloom consisting of 97% Microcystis spp. was present. In September 83% of the cyanobacterial biomass was composed of Anabaena spiroides and only 8% was Microcystis spp. In the Bay of Quinte elevated microcystin concentrations were associated with higher soluble reactive P levels, lower seston C:P molar ratios, and lower total N. In Maumee Bay microcystin levels were higher in August 2006 (total mean= 4.45 μg/L) than they were in June 2006 (<0.05 μg/L). In August a cyanobacterial bloom consisting of 22% Microcystis spp. and 48% Aphanizomenon flos-aquae was observed. Higher microcystin concentrations in Maumee Bay were associated with decreased total N: total P molar ratios, increased total P, and decreased water transparency as measured by Secchi depth. Belwood Lake had the highest microcystin levels of the three reservoirs but only once exceeded the recommended World Health Organization concentration of 1.0 μg/L. Belwood Lake’s largest cyanobacterial bloom in October 2005 was accompanied by relatively low microcystin levels (<0.2 μg/L). Conestogo and Guelph lakes always had microcystin levels below 0.2 μg/L and 0.6 μg/L, respectively. In the Grand River reservoirs, increased microcystin concentrations were associated with higher chlorophyll a, higher light attenuation coefficients, lower total N, lower total N: total P molar ratios, higher C:P molar ratios, lower nitrate, higher cyanobacterial biomass, and higher total P. When data from the Bay of Quinte, Maumee Bay, and Grand River reservoirs were pooled, total microcystin had the most significant positive correlation with total P. Total microcystin and water temperature also had a significant positive correlation.

Anatoxin-a (ANTX) is a neurotoxin produced by several freshwater cyanobacteria and has been implicated in the death of livestock and domestic animals from consumption of tainted surface waters. ANTX is unstable under normal conditions and is somewhat problematic to extract and study. Accelerated solvent extraction (ASE) combined with liquid chromatography-mass spectrometry (LC/MS) was used to develop an efficient extraction and analytical method for both ANTX and the more commonly encountered hepatotoxic microcystins produced by cyanobacteria. The effects of nitrogen supply on the cellular production and release of ANTX was investigated in Aphanizomenon issatschenkoi (Ussaczew) Proschkina-Lavrenko (Nostocales). In contrast to the predictions of the carbonnutrient balance hypothesis, the maximum production was observed under moderate N stress. In addition, steady state fugacity-based models were employed to investigate ANTX’s distribution and fate in freshwater ecosytems. ANTX was not found to be very persistent in aquatic ecosystems and did not appear to bioaccumulate in fish, at least not from the dissolved phase.

Made available in DSpace on 2014-06-11T19:23:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-30Bitstream added on 2014-06-13T18:50:13Z : No. of bitstreams: 1 hereman_tc_me_rcla.pdf: 346939 bytes, checksum: eea54caf1fb86eb9e0c1d403eabf0878 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Plantas cultivadas podem ser contaminadas com cianotoxinas através de irrigação com água contendo cianobactérias tóxicas. Uma espécie freqüentemente encontrada nos corpos d’agua é Microcystis aeruginosa, produtora da microcistina (MC), uma toxina hepatotóxica. Frente a esta possibilidade, nosso objetivo foi investigar os efeitos de extrato bruto de uma linhagem produtora de microcistina (BCCUSP232) e outra não produtora (BCCUSP03) em bioensaio de germinação de sementes e crescimento da hortaliça alface e a possibilidade de bioacumulação da cianotoxina nos tecidos foliares. Sementes germinadas em papel de filtro foram expostas a concentrações entre 0,5 a 100 μg.L-1 de MC-LR durante sete dias, enquanto as plantas cultivadas em vasos contendo substrato comercial para hortaliça foram irrigadas com 100ml de solução aquosa contendo 0,5 a 10 μg.L-1 de MC-LR durante 15 dias ao final do ciclo da cultura. Valores de massa seca correspondentes foram empregados para o tratamento com extrato bruto sem microcistina, além de controle com água. Os efeitos nocivos da MC-LR puderam ser observados no desenvolvimento das plântulas expostas a 75 e 100 μg.L-1, concentrações que induziram uma maior ocorrência de plântulas anormais devido ao aparecimento de necrose na radícula e encurtamento deste órgão nas plântulas normais, como também redução no teor de clorofila e aumento na atividade da enzima antioxidante peroxidase. Para as plantas adultas, a exposição às diferentes concentrações de MC-LR não interferiram no teor de clorofila e na atividade da peroxidase. Contudo, ambos os extratos (com e sem MC-LR) interferiram igualmente na permeabilidade seletiva da membrana plasmática das folhas da planta adulta, mesmo em baixa concentração, podendo assim deixá-la mais suscetível a estresses abióticos e bióticos. Embora as plantas se apresentassem saudáveis... / Crop plants may become contaminated with cyanotoxins during irrigation with water containing toxic cyanobacteria, such as Microcystis aeruginosa, which produces the hepatoxin microcystin (MC). The aim of the present study was to investigate the effects of a crude extract from a microcystin-producing strain (BCCUSP232) and non-microcystin-producing strain (BCCUSP03) on germination and growth bioassays of lettuce and assess the possibility of the bioaccumulation of this cyanotoxin in leaf tissue. Seeds germinated on filter paper were exposed to concentrations of 0.5 to 100 μg.L-1 of MC-LR for seven days, while plants grown in pots containing a commercial substrate were irrigated with 100mL of an aqueous solution containing 0.5 to 10 μg.L-1 of MC-LR for 15 days at the end of the culture cycle. The corresponding dry weight values were used for treatment with the crude extract without microcystin. Control plants received only water. The harmful effects of MC-LR were observed during the development of seedlings exposed to 75 and 100 μg.L-1, with a higher incidence of abnormal seedlings due to the onset of root necrosis as well as a shortening of roots in normal seedlings, a reduction in chlorophyll content and an increase in the activity of the antioxidant enzyme peroxidase. In adult plants, exposure to different concentrations of MC-LR did not affect the chlorophyll content or peroxidase activity. However, even at low concentrations, both extracts (with and without MC-LR) equally affected the selective permeability of the plasma membrane in leaves, which could make the plants more susceptible to biotic and abiotic stresses. Although the plants looked healthy and similar to the controls, there was an accumulation of microcystin in the leaves at concentrations of 7.2 μg.kg-1 and 167.1 μg.kg-1 when... (Complete abstract click electronic access below)

Orientador: Maria do Carmo Bittencourt de Oliveira / Banca: Massanori Takaki / Banca: Sergio Florentino Pascolatti / Resumo: Plantas cultivadas podem ser contaminadas com cianotoxinas através de irrigação com água contendo cianobactérias tóxicas. Uma espécie freqüentemente encontrada nos corpos d'agua é Microcystis aeruginosa, produtora da microcistina (MC), uma toxina hepatotóxica. Frente a esta possibilidade, nosso objetivo foi investigar os efeitos de extrato bruto de uma linhagem produtora de microcistina (BCCUSP232) e outra não produtora (BCCUSP03) em bioensaio de germinação de sementes e crescimento da hortaliça alface e a possibilidade de bioacumulação da cianotoxina nos tecidos foliares. Sementes germinadas em papel de filtro foram expostas a concentrações entre 0,5 a 100 μg.L-1 de MC-LR durante sete dias, enquanto as plantas cultivadas em vasos contendo substrato comercial para hortaliça foram irrigadas com 100ml de solução aquosa contendo 0,5 a 10 μg.L-1 de MC-LR durante 15 dias ao final do ciclo da cultura. Valores de massa seca correspondentes foram empregados para o tratamento com extrato bruto sem microcistina, além de controle com água. Os efeitos nocivos da MC-LR puderam ser observados no desenvolvimento das plântulas expostas a 75 e 100 μg.L-1, concentrações que induziram uma maior ocorrência de plântulas anormais devido ao aparecimento de necrose na radícula e encurtamento deste órgão nas plântulas normais, como também redução no teor de clorofila e aumento na atividade da enzima antioxidante peroxidase. Para as plantas adultas, a exposição às diferentes concentrações de MC-LR não interferiram no teor de clorofila e na atividade da peroxidase. Contudo, ambos os extratos (com e sem MC-LR) interferiram igualmente na permeabilidade seletiva da membrana plasmática das folhas da planta adulta, mesmo em baixa concentração, podendo assim deixá-la mais suscetível a estresses abióticos e bióticos. Embora as plantas se apresentassem saudáveis... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Crop plants may become contaminated with cyanotoxins during irrigation with water containing toxic cyanobacteria, such as Microcystis aeruginosa, which produces the hepatoxin microcystin (MC). The aim of the present study was to investigate the effects of a crude extract from a microcystin-producing strain (BCCUSP232) and non-microcystin-producing strain (BCCUSP03) on germination and growth bioassays of lettuce and assess the possibility of the bioaccumulation of this cyanotoxin in leaf tissue. Seeds germinated on filter paper were exposed to concentrations of 0.5 to 100 μg.L-1 of MC-LR for seven days, while plants grown in pots containing a commercial substrate were irrigated with 100mL of an aqueous solution containing 0.5 to 10 μg.L-1 of MC-LR for 15 days at the end of the culture cycle. The corresponding dry weight values were used for treatment with the crude extract without microcystin. Control plants received only water. The harmful effects of MC-LR were observed during the development of seedlings exposed to 75 and 100 μg.L-1, with a higher incidence of abnormal seedlings due to the onset of root necrosis as well as a shortening of roots in normal seedlings, a reduction in chlorophyll content and an increase in the activity of the antioxidant enzyme peroxidase. In adult plants, exposure to different concentrations of MC-LR did not affect the chlorophyll content or peroxidase activity. However, even at low concentrations, both extracts (with and without MC-LR) equally affected the selective permeability of the plasma membrane in leaves, which could make the plants more susceptible to biotic and abiotic stresses. Although the plants looked healthy and similar to the controls, there was an accumulation of microcystin in the leaves at concentrations of 7.2 μg.kg-1 and 167.1 μg.kg-1 when... (Complete abstract click electronic access below) / Mestre

Anatoxin-a (ANTX) is a neurotoxin produced by several freshwater cyanobacteria and has been implicated in the death of livestock and domestic animals from consumption of tainted surface waters. ANTX is unstable under normal conditions and is somewhat problematic to extract and study. Accelerated solvent extraction (ASE) combined with liquid chromatography-mass spectrometry (LC/MS) was used to develop an efficient extraction and analytical method for both ANTX and the more commonly encountered hepatotoxic microcystins produced by cyanobacteria. The effects of nitrogen supply on the cellular production and release of ANTX was investigated in Aphanizomenon issatschenkoi (Ussaczew) Proschkina-Lavrenko (Nostocales). In contrast to the predictions of the carbonnutrient balance hypothesis, the maximum production was observed under moderate N stress. In addition, steady state fugacity-based models were employed to investigate ANTX’s distribution and fate in freshwater ecosytems. ANTX was not found to be very persistent in aquatic ecosystems and did not appear to bioaccumulate in fish, at least not from the dissolved phase.