Relevant bibliographies by topics / Saxitoxin

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Academic literature on the topic 'Saxitoxin'

Author: Grafiati
Published: 4 June 2021
Last updated: 30 July 2024

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Journal articles on the topic "Saxitoxin"

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Moustaka-Gouni, Maria, Anastasia Hiskia, Savvas Genitsaris, Matina Katsiapi, Korina Manolidi, Sevasti-Kiriaki Zervou, Christophoros Christophoridis, Theodoros M. Triantis, Triantafyllos Kaloudis, and Sotiris Orfanidis. "First report of Aphanizomenon favaloroi occurrence in Europe associated with saxitoxins and a massive fish kill in Lake Vistonis, Greece." Marine and Freshwater Research 68, no. 4 (2017): 793. http://dx.doi.org/10.1071/mf16029.

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The cyanobacterium Aphanizomenon favaloroi was identified for the first time in Europe in the Mediterranean brackish Lake Vistonis during July–August 2014. It formed a dense bloom (from 16×106 to 81×106 trichomes L–1), causing a brown colouration of the lake water. When A. favaloroi formed 100% of the total phytoplankton biomass (44mg L–1), saxitoxins (saxitoxin and neo-saxitoxin) were detected in the lake seston (42 and 17μg g–1 phytoplankton dry weight respectively), which was screened for saxitoxins, cylindrospermopsin, anatoxin-a, microcystins and nodularin. A massive fish kill coincided with the A. favaloroi bloom. This new saxitoxin-producing species of cyanobacteria, with traits for successful dispersal, may pose a health risk to animals and humans and cause adverse effects on water quality and water services because of its expansion potential.
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Casali, Simone Pereira, André Cordeiro Alves Dos Santos, Patrícia Bortoletto de Falco, and Maria do Carmo Calijuri. "Influence of environmental variables on saxitoxin yields by Cylindrospermopsis raciborskii in a mesotrophic subtropical reservoir." Journal of Water and Health 15, no. 4 (March 25, 2017): 509–18. http://dx.doi.org/10.2166/wh.2017.266.

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Saxitoxins are a class of toxins produced by at least two groups of evolutionarily distant organisms (cyanobacteria and dinoflagellates). While the toxicity of these toxins is relatively well characterized, to date little is known about their drivers and ecological functions, especially in lower latitude tropical and subtropical freshwater ecosystems. In the present study, we aimed to obtain a better understanding of the main drivers of saxitoxin concentrations in aquatic environments. We investigated the relationships among saxitoxin concentrations in a mesotrophic subtropical reservoir dominated by the cyanobacteria Cylindrospermopsis raciborskii with physical, chemical and biological water variables. The highest saxitoxin concentrations were 0.20 μg·L−1, which occurred in the samples with the highest densities of C. raciborskii (maximum of 4.3 × 104 org·mL−1) and the highest concentration of dissolved nutrients (nitrate from 0.2 to 0.8 μg·L−1, ortophosphate from 0.3 to 8.5 μg·L−1). These correlations were confirmed by statistical analyses. However, the highest saxitoxin relative concentrations (per trichome) were associated with lower C. raciborskii densities, suggesting that saxitoxin production or the selection of saxitoxin-producing strains was associated with the adaptation of this species to conditions of stress. Our results indicate that C. raciborskii toxin yields vary depending on the enrichment conditions having potential implications for reservoir management.
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Truman, Penelope, and Robin J. Lake. "Comparison of Mouse Bioassay and Sodium Channel Cytotoxicity Assay for Detecting Paralytic Shellfish Poisoning Toxins in Shellfish Extracts." Journal of AOAC INTERNATIONAL 79, no. 5 (September 1, 1996): 1130–33. http://dx.doi.org/10.1093/jaoac/79.5.1130.

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Abstract A neuroblastoma cell culture assay was used to analyze shellfish extracts for presence of paralytic shellfish poisoning toxins (saxitoxins). Results were compared with mouse bioassays performed as part of a screening program for shellfish toxins in New Zealand. Twenty-nine samples gave negative results in both assays. Fifty-seven samples gave positive results in at least one assay. The correlation between the assays for saxitoxin equivalent levels in shellfish was 0.867. In spiking studies on shellfish extracts, the neuroblastoma assay showed a good response to added saxitoxin. Although these results support use of the neuroblastoma assay as a screening procedure for shellfish toxicity, results close to regulatory limits should be confirmed by mouse bioassay.
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Grachev, Mikhail, Ilya Zubkov, Irina Tikhonova, Maria Ivacheva, Anton Kuzmin, Elena Sukhanova, Ekaterina Sorokovikova, et al. "Extensive Contamination of Water with Saxitoxin Near the Dam of the Irkutsk Hydropower Station Reservoir (East Siberia, Russia)." Toxins 10, no. 10 (October 1, 2018): 402. http://dx.doi.org/10.3390/toxins10100402.

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An area of discolored water 50 m wide and 30 m long was found in September 2017 close to the dam of the Irkutsk hydroelectric power station. Water from this spot was sampled for investigation in the present study. Microscopic analysis revealed that the suspended matter in the sample was composed of clumps of filaments, vegetative cells, akinetes and heterocysts that formed short filaments and solitary cells. This matter was found to consist of partially degraded cells of the cyanobacterium Dolichospermum lemmermannii. Nucleotide sequencing of DNA isolated from the biomass revealed the presence of the sxtA gene which is involved in the synthesis of saxitoxin. Water from the polluted area contained 600 ± 100 μg L−1 saxitoxin as measured by HPLC-MS with pre-column modification of the toxin with 2,4-dinitrophenylhydrazine. Immunoassay analysis (ELISA) showed a concentration of saxitoxins in the water of 2900 ± 900 μg L−1. Hydrochemical and microbiological analyses suggested the contaminated area appeared as a result of a D. lemmermannii bloom, followed by its decay and release of saxitoxin and nutrients. The present paper describes the results of a case study. Better understanding of the phenomenon will depend on the possibility to perform implementation of a large-scale monitoring program.
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Duncan, Keith G., Jacque L. Duncan, and Daniel M. Schwartz. "Saxitoxin." Cornea 20, no. 6 (August 2001): 639–42. http://dx.doi.org/10.1097/00003226-200108000-00016.

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Thottumkara, Arun P., William H. Parsons, and J. Du Bois. "Saxitoxin." Angewandte Chemie 126, no. 23 (April 25, 2014): 5868–94. http://dx.doi.org/10.1002/ange.201308235.

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Thottumkara, Arun P., William H. Parsons, and J. Du Bois. "Saxitoxin." Angewandte Chemie International Edition 53, no. 23 (April 25, 2014): 5760–84. http://dx.doi.org/10.1002/anie.201308235.

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Egmond, Hans P. van, Antonio Mouriño, Pedro A. Burdaspal, Achim Boenke, P. Alvito, F. Arevalo, L. M. Botana-López, et al. "Development of Reference Materials for Paralytic Shellfish Poisoning Toxins." Journal of AOAC INTERNATIONAL 84, no. 5 (September 1, 2001): 1668–76. http://dx.doi.org/10.1093/jaoac/84.5.1668.

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Abstract A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and characterization of calibrants; (2) improvement of analytical methodology; (3) preparation of reference materials, including homogeneity and stability studies; (4) 2 interlaboratory studies and a certification exercise. The joint activities resulted in 3 homogeneous and stable reference materials: 2 lyophilized mussel materials with and without naturally incurred paralytic shellfish poisoning (PSP) toxins, and a saxitoxin enrichment solution. The reference materials were certified with respect to their saxitoxin and decarbamoyl-saxitoxin content. The lyophilized mussel material with PSP toxins (CRM 542) contained <0.07 mg saxitoxin·2HCl/kg and 1.59 ± 0.20 mg decarbamoyl-saxitoxin·2HCl/kg. The lyophilized mussel material without PSP toxins (CRM 543) contained <0.07 mg saxitoxin·2HCl/kg and <0.04 mg decarbamoyl-saxitoxin·2HCl/kg. The certified value of the saxitoxin mass fraction in the saxitoxin enrichment solution (CRM 663) was 9.8 ± 1.2 μg/g.
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Ho, Lionel, Paul Tanis-Plant, Nawal Kayal, Najwa Slyman, and Gayle Newcombe. "Optimising water treatment practices for the removal of Anabaena circinalis and its associated metabolites, geosmin and saxitoxins." Journal of Water and Health 7, no. 4 (July 1, 2009): 544–56. http://dx.doi.org/10.2166/wh.2009.075.

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The cyanobacterium Anabaena circinalis has the ability to co-produce geosmin and saxitoxins, compounds which can compromise the quality of drinking water. This study provides pertinent information in optimising water treatment practices for the removal of geosmin and saxitoxins. In particular, it demonstrates that pre-oxidation using potassium permanganate could be applied at the head of water treatment plants without releasing intracellular geosmin and saxitoxins from A. circinalis. Furthermore, powdered activated carbon (PAC) was shown to be an effective treatment barrier for the removal of extracellular (dissolved) geosmin and saxitoxins, with similar adsorption trends of both compounds. The relative removal of the saxitoxins compared with geosmin was determined to be 0.84±0.27, which implies that saxitoxin removal with PAC can be estimated to be approximately 60 to 100% of the removal of geosmin under equivalent conditions. Chlorine was shown to be effective for the oxidation of the saxitoxins with CT values of approximately 30 mg min l−1 required for greater than 90% destruction of the saxitoxins.
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Newcombe, G., and B. Nicholson. "Treatment options for the saxitoxin class of cyanotoxins." Water Supply 2, no. 5-6 (December 1, 2002): 271–75. http://dx.doi.org/10.2166/ws.2002.0179.

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The saxitoxin class of algal toxins (cyanotoxins) are neurotoxins produced in Australia by the blue-green alga (cyanobacterium) Anabaena circinalis. A range of water treatment processes was investigated for the removal of these compounds. Ozonation of the toxins at moderate doses was found to be ineffective. Chlorination was found to be effective at high pH; therefore where pH adjustment is possible in the treatment process, chlorination could be considered as an important treatment option. Activated carbon, both in the granular and powdered form, was effective for reducing the toxicity of a mixture of the toxins as the most toxic of the saxitoxins were also the most readily removed by adsorption.
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Dissertations / Theses on the topic "Saxitoxin"

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Cavaliere, Rosalia Biotechnology &amp Biomolecular Sciences Faculty of Science UNSW. "The regulation of Saxitoxin production in Cyanobacteria." Publisher:University of New South Wales. Biotechnology & Biomolecular Sciences, 2008. http://handle.unsw.edu.au/1959.4/44403.

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Aquatic microalgae produce a variety of toxic secondary metabolites, which are a concern for public health and seafood industries, while also presenting a source of pharmacologically valuable compounds. The present study deals with the physiology and molecular genetics of saxitoxin (STX), a cyanobacterial neurotoxic alkaloid. Ecological and chemical parameters have been investigated for their effects on growth and STX production in the cyanobacterium Cylindrospermopsis raciborskii T3, in order to better understand the physiological responses of this cyanobacterium to the anthropogenic eutrophication of water bodies. The results indicated that phosphate, in particular, had an incremental effect on STX production, as well as promoting the up-regulation of transcription of the STX biosynthetic gene cluster (sxt). High temperature was found to negatively affect growth and STX production in this organism. The effects of the plant hormone, jasmonic acid, were also tested, since it has previously been shown to affect plant alkaloid production. The hypothesised similarity between cyanobacterial and plant secondary metabolism in response to this plant hormone was confirmed in the neurotoxic cyanobacterium, C. raciborskii T3, as well as the non-toxic Anabaena sp. PCC7120. Furthermore, investigation of the sxt gene cluster transcriptional map in C. raciborskii T3 was carried out, with identification of three main polycistronic and one monocistronic transcripts. Promoter regions putatively involved in the regulation of STX production in C. raciborskii T3 were also identified. Transcription factor consensus motifs, the pho boxes, were identified in the main promoter region. These conserved motifs are the binding regions for the transcriptional regulator, PhoB, to the pho regulon genes, involved in phosphate uptake during conditions of its depletion in the environment. Moreover, a genomic region adjacent to the sxt gene cluster in C. raciborskii T3 was identified and characterised, putatively encoding a regulatory two-component system. This system appears to be involved in the sensing of environmental signals, in particular depleted phosphate, while activating the transcription of genes involved in its uptake and transport. The results of this study lead to a greater understanding of the complex factors associated with the regulation of STX biosynthesis and bloom-formation, by the cyanobacterium C. raciborskii T3.
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Giraldi, Laís Albuquerque. "Efeitos da concentração de micronutrientes no crescimento e na produção de saxitoxina em Cylindrospermopsis raciborskii." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-19012015-102222/.

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A espécie de cianobactéria Cylindrospermopsis raciborskii vem se destacando na literatura atual devido à sua presença e dominância em lagos e reservatórios em diversas regiões do planeta e a principal preocupação deste cenário é por ela ser potencialmente tóxica. Estudos revelaram que o crescimento e a síntese de toxinas em espécies de microrganismos fitoplanctônicos estão atrelados à limitação ou excesso de micronutrientes, porém, ainda são desconhecidos os efeitos desta variação na produção de saxitoxina (STX) por C. raciborskii. Para contribuir com o esclarecimento desta questão, investigou-se o efeito de diferentes concentrações dos micronutrientes Fe, Zn, Cu, Mn, Co e B no crescimento e na produção de STX de uma linhagem de C. raciborskii. Em salas climatizadas, culturas desta linhagem foram expostas durante 20 dias a 5 concentrações de cada micronutriente, com alteração do meio de cultura ASM-1. As respostas fisiológicas de C. racibosrkii a estas modificações foram verificadas através da velocidade máxima de crescimento (μmáx), rendimento do biovolume, tempo de duplicação (Td), concentração de clorofila a, assimilação de nitrato e ortofosfato e síntese de STX total (intra e extracelular). As maiores concentrações de STX por biovolume (STX/biovolume) foram obtidas nos tratamentos com baixa concentração de Fe (0,4 μM) e elevada concentração de Cu (0,8 μM). Nos micronutrientes Zn, Co e B, houve uma tendência de redução da síntese de STX nas maiores concentrações destes metais. Enquanto as concentrações extremas de Fe e Mn inibiram o crescimento (Fe: 0,4 e 400 μM e Mn: 0,7 e 600 μM), as concentrações centrais favoreceram (Fe: 4 a 60 μM e Mn: 7 a 200 μM). Elevada concentração de Cu (0,8 μM) causou aumento de 2,6 vezes (160%) do volume celular e redução na síntese de clorofila a, sem alterações significativas em μmáx e rendimento. O aumento da concentração dos micronutrientes Fe, Zn, Mn e B no meio de cultura causaram maior assimilação de ortofosfato por biovolume (P/biovolume). Estes principais resultados demonstraram que os micronutrientes afetam a síntese de STX e o crescimento de C. raciborskii, podendo ser associados aos diversos mecanismos de captura e detoxificação de metais que as cianobactérias possuem. Embora as extrapolações dos resultados laboratoriais para o ambiente devam ser realizadas com prudência, estudos relacionados à ecofisiologia de cianobactérias como este, são fundamentais para análise criteriosa de cada variável podendo ser utilizado como ferramenta de diagnóstico e prevenção de florações tóxicas.
Cylindrospermopsis raciborskii has been highlighted in several researches due to the dominance in many lakes and reservoirs around the world, the main concern about it due to the ability to produce toxins. Studies have revealed that growth and toxins production in phytoplankton species are linked to micronutrients limitation or excess. Nevertheless, micronutrient variation effects on saxitoxin (STX) production by C. raciborskii are still unknown. To contribute to clarify this issue, we investigated the effect of different micronutrients concentration, such as Fe, Zn, Cu, Mn, Co and B, on the growth and saxitoxin production of C. raciborskii strain. In climatized growth room, the cultures of C. raciborskii strain were exposed to 5 different concentration of each micronutrient, present in ASM-1 medium, during 20 days. The C. racibosrkii physiological responses was detected through maximum growth rate (μmáx), biovolume yield, doubling time (Td), chlorophyll-a, nitrate and orthophosphate assimilation and the total STX production (intra and extracellular). The higher concentrations of STX per biovolume (STX/biovolume) were observed in treatments with low Fe concentration (0.4 μM) and high Cu concentrations (0.8 μM). Higher concentrations of Zn, Co and B lead to low STX production. While the Fe and Mn extreme concentrations inhibited the growth (Fe: 0.4 and 400 μM and Mn: 0.7 to 600 μM), the central concentrations favored (Fe: 4 to 60 μM, and Mn: 7-200 μM). A high Cu concentration (0,8 μM) leads to 2,6 fold increase (160%) in cellular volume and decrease the chlorophyll-a content, however máx and biovolume yield did not change. Increasing the Fe, Zn, Mn and B concentration in the culture caused higher assimilation of orthophosphate per biovolume (P/biovolume). These results indicated that micronutrients affected C. raciborskii growth and STX production, and may be associated with the diverse cyanobacterial mechanisms of metals capture and detoxification. Cyanobacteria ecophysiology studies, as this research, are fundamental to careful analysis of each variable, which could be used as diagnostic and a tool to prevention of toxic blooms.
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Lerche, Luciana Haipek Mosolino. "Proposta de modelo de exposição humana à saxitoxina em águas de recreação e de abastecimento público do reservatório Itupararanga." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/6/6143/tde-11072018-132843/.

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O aporte artificial de nutrientes nos ambientes aquáticos tem favorecido a incidência de florações de cianobactérias, causando impactos na qualidade da água e colocando em risco a saúde humana. O gênero de cianobactéria Cylindrospermopsis, amplamente distribuído em água doce pelo mundo, é capaz de produzir diversas cianotoxinas, dentre elas saxitoxina e análogos. O objetivo deste trabalho foi elaborar um modelo de exposição referente à ingestão de água contaminada por saxitoxina e análogos através da recreação de contato primário e do consumo de água. Os dados de densidade de células de Cylindrospermopsis e de concentrações de saxitoxina e análogos na água bruta foram obtidos da Rede de Monitoramento de Qualidade de Águas Superficiais da CETESB (2015 e 2016) do reservatório Itupararanga. O modelo conceitual de exposição e o cálculo da ingestão diária crônica de saxitoxina e análogos consideraram: concentrações máxima e mínima de saxitoxina e análogos encontradas na água bruta do reservatório, vias de exposição, população exposta, taxa de ingestão de água, frequência e duração da exposição, peso corporal para adultos (maiores de 21 anos) e crianças (menores de 5 anos), para cenários de exposição relativos à recreação de contato primário e consumo de água potável. Os valores de células de cianobactérias estiveram entre 2.216 e 203.082 céls.mL-1 e as concentrações de saxitoxina e análogos estiveram entre 0,04 e 0,37 µg equivalente STX..L-1. Os resultados obtidos na análise da água bruta do reservatório, estiveram abaixo do valor estabelecido na legislação brasileira para água potável (3 µg equivalente STX.L-1), mas não atenderiam as especificações adotadas por Oregon e Ohio (0,3 µg equivalentes STX.L-1) e à proposta em discussão no Comitê Permanente para Gestão Integrada da Qualidade da Água destinada ao Consumo Humano no Estado de São Paulo (0,13 µg equivalente STX.L-1), indicando a possibilidade da ocorrência de efeito adverso à saúde em grupos sensíveis que utilizem água do reservatório, dependendo da eficiência de remoção dessas cianotoxinas no processo de tratamento. Os valores de ingestão diária crônica estimados, para recreação, variaram de 2,55 x 10-6 a 1,08 x 10-4 µg equivalente STX. kg-1.dia-1 (adultos) e 2,78 x 10-9 a 4,35 x 10-4 µg equivalente STX. kg-1.dia-1 (crianças). Para ingestão de água potável, esses valores variaram de 2,5 x 10-4 a 1,47 x 10-2 µg equivalente STX. kg-1.dia-1 (adultos) e 5,36 x 10-5 a 2,55 x 10-2 µg equivalente STX. kg-1.dia-1 (crianças). Esses valores indicaram que as crianças estão mais expostas que os adultos, fato preocupante, pois elas são mais sensíveis aos efeitos de substâncias tóxicas, e apesar de estudos indicarem efeitos da saxitoxina em cultura de células neurais, sua capacidade de atravessar a barreira hematoencefálica e de causar danos cognitivos em ratos, os efeitos da exposição crônica em humanos ainda são desconhecidos. Não foi possível estimar os riscos à saúde da população exposta à saxitoxina e análogos, pela falta de dados na literatura, porém o modelo de exposição proposto é um avanço para a identificação de lacunas para a condução da avaliação de risco à saúde humana considerando a exposição crônica.
The artificial enrichment of nutrients in aquatic environments has favored the incidence of cyanobacteria blooms, causing impacts on water quality and putting human health at risk. The genus of cyanobacteria Cylindrospermopsis, widely distributed throughout the world in freshwater environments, is able to produce cianotoxin, among them saxitoxin and its analogues. The objective of this work was to elaborate a model of exposure referring to the ingestion of water contaminated by saxitoxin and analogues through recreation of primary contact and water consumption. Cylindrospermopsis cell density and saxitoxin and analogues concentrations in surface water were obtained from the CETESB Surface Water Quality Monitoring Network for the Itupararanga reservoir in 2015 and 2016. The development of the conceptual model of exposure and the calculation of the chronic daily intake of saxitoxin and analogues, considered: maximum and minimum concentrations of saxitoxin and analogues found in the raw water of the reservoir, route of exposure, exposed population, rate of water intake, frequency and duration of exposure, body weight for adults (over 21 years) and children (under 5 years), for exposures scenarios concerning recreation of primary contact and consumption of drinking water. The values of cyanobacteria cells were between 2,216 and 203,082 cells.L-1 and the concentrations of saxitoxin and analogues were between 0.04 and 0.37 µg STX equivalent. L-1. The comparison of these variables indicated a significant positive correlation between them. The results obtained in the raw water analysis of the reservoir were below the value established in Brazilian legislation for drinking water (3 µg equivalent STX.L-1), but would not meet the specifications adopted by US states Oregon and Ohio (0.3 µg equivalents.L-1) and the proposed value for the Standing Committee for Integrated Water Quality Management for Human Consumption in the State of São Paulo (0,13 µg equivalent STX.L-1), indicating the possibility of adverse health effects in sensitive groups using water from the reservoir. Estimated chronic daily intake values, for recreation, ranged from 2.55 x 10-6 to 1.08 x 10-4 µg STX equivalent. kg-1.day-1 (adults) and 2.78 x 10-9 to 4.35 x 10-4 µg STX equivalent. kg-1.day-1 (children). For water intake, these values ranged from 2.5 x 10-4 to 1.47 x 10-2 µg STX equivalent. kg-1 day-1 (adults) and 5.36 x 10-5 to 2.55 x 10-2 µg STX equivalent. kg-1. day-1 (children). These values indicated that children are more exposed than adults, a worrying fact because they are generally more sensitive to the effects of toxic substances than adults, and although studies indicate that saxitoxin was able to cross the blood brain barrier and to cause cognitive damage in rats, as well as changes in neural cell cultures, the effects of chronic exposure in humans are still unknown. It was not possible to estimate the health risks of the population exposed to saxitoxin and the like, due to the lack of data in the literature, but the proposed exposure model is an advance for the identification of gaps for conducting the human health risk assessment considering the exposure chronic.
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Pengelly, Jasper John Lobl Biotechnology &amp Biomolecular Sciences Faculty of Science UNSW. "Molecular characterisation of membrane transporters associated with saxitoxin biosynthesis in cyanobacteria." Publisher:University of New South Wales. Biotechnology & Biomolecular Sciences, 2008. http://handle.unsw.edu.au/1959.4/41429.

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The release of the neurotoxic alkaloid saxitoxin by cyanobacterial cells was previously thought to occur primarily after cell lysis, yet recent evidence also suggests active toxin export by membrane transporters. Transporter proteins associated with STX biosynthesis in Cylindrospermopsis raciborskii T3 (sxtF and sxtM) and Anabaena circinalis 131C (naDt) were predicted to be involved in the export of STX from cyanobacterial cells. The main aim of this project was to characterise the transporters associated with STX biosynthesis, by investigation of their genetic prevalence, functional substrates and specific regulation. An sxtM homologue was discovered in A. circinalis 131C, as part of an sxt cluster, and found to be uniquely associated with STX-producing strains. Bioinformatic and phylogenetic analysis showed that the translated sxt transporters clustered with the NorM prokaryotic MATE sub-family and membrane topology analysis predicted 12 membrane-spanning regions. To characterise the functional substrates of the putative STX-transporters, they were heterologously expressed in the antibiotic-sensitive E. coli strain KAM32. Expression of the sxt MATES complemented host sensitivity to the cationic fluroquinolone antibiotics, ciprofloxacin and ofloxacin. Disruption of gene homologues of naDt and the sxt MATE genes in Synechocystis sp. PCC6803 yielded mutant strains with increased sensitivity to the toxic organic cations, methyl viologen and acriflavine. Transcription of the putative STX transporters, and the putative STX biosynthesis gene sxtA, was studied in C. raciborskii T3 and A. circinalis 131C under alkali and Na+ stress. Alkali stress (pH 9) decreased total STX levels in A. circinalis 131C and was correlated with a down-regulation of the putative transport and biosynthetic genes. In C. raciborskii T3, alkali stress promoted higher extracellular but lower intracellular STX levels, which also correlated with large increases in transcription of the putative STX transport genes.
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Barber, Kathleen Gladys. "Response of the shore crabs Hemigrapsus oregonesis and Hemigrapsus nudus to paralytic shellfish toxins." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27797.

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The following research deals with the response of the small shore crabs, Hemigrapsus oreqonesis and Hemigrapsus nudus to paralytic shellfish toxins (PST). These shore crabs were shown to develop a remarkable seasonal resistance to administered saxitoxin (STX). No similar change in sensitivity was found after administration of tetrodotoxin (TTX), another marine neurotoxin with similar actions to the PST. Resistance to STX in the small shore crabs was linked to the presence of PST in the viscera, and this in turn was related to the presence of toxic dinoflagellate blooms in the area. Furthermore, this research provides, for the first time, evidence of a protein component (MW 145,000 daltons) which appears to be associated with acquired resistance to PST in the shore crab. In addition, this protein component was shown to appear in sensitive crab extracts after the administration of low doses of saxitoxin and tetrodotoxin in vivo.
Land and Food Systems, Faculty of
Graduate
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Guimarães, Hindria Renally Cavalcanti. "Avaliação da remoção de saxitoxina no tratamento de água de abastecimento em sistema convencional seguido de adsorção em carvão ativado granular (CAG)." Universidade Estadual da Paraíba, 2012. http://tede.bc.uepb.edu.br/tede/jspui/handle/tede/1916.

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The research aimed to evaluate the saxitoxin removal of the water supply in the conventional system followed by adsorption through granular activated carbon (GAC). The experiment was performed in three steps. In the first, coagulation diagrams were constructed for the aluminum sulfate. In the second stage, tests were conducted with aluminum sulfate and auxiliary coagulant (anionic and cationic polymers). In the third stage was carried conventional treatment (coagulation / flocculation /sedimentation / filtration) followed by adsorption on a column of granular activated carbon (GAC), in bench scale. The system was composed of a polypropylene plastic container for the storage of decanted water derived from the jar tests, with a capacity of 100 liters. The reservoir is connected via two peristaltic pumps with controlled flow for 1L/ h. Each pump is connected to two sand laboratory filters (SLF), which connected themselves to two columns of CAG, CC1 and CC2, with different coal granulometries. The system was monitored for 48 hours. The results of the coagulation tests showed good removal efficiency (>50%) for water of study (WS) at the natural pH of water (7.6), at a dosage of aluminum sulfate 25 mg/L, both in terms of turbidity and remaining true color. When evaluated the representability of the data, it was observed that the removal efficiency was not repeated. In the third stage, there was low saxitoxin removal by conventional treatment (7%), the removal was processed in the adsorption columns. CC1 and CC2 obtained removals ranging from 100 to 70%. However, for the maximum percentage removal CC2 removed greater amount of saxitoxin per unit time compared to CC1, nearly six hours of difference. The Langmuir and Freundlich isotherms showed better settings to the CC2 for the evaluated samples of activated carbon.
A pesquisa teve como objetivo principal avaliar a remoção de saxitoxina de água de abastecimento utilizando tratamento convencional seguido de adsorção por carvão ativado granular (CAG). O experimento foi realizado em três etapas. Na primeira, foram construídos diagramas de coagulação para o sulfato de alumínio. Na segunda etapa, foram realizados ensaios com sulfato de alumino e coagulantes auxiliares (polímeros aniônicos e catiônicos). Na terceira etapa foi realizado o tratamento convencional (coagulação/ floculação/ sedimentação/ filtração) seguido de adsorção em coluna de carvão ativado granular (CAG), em escala de bancada. O sistema esteve formado por um reservatório de plástico de polipropileno para o armazenamento de água decantada proveniente do jar tests, com capacidade para 100 litros. O reservatório foi interligado por intermédio de duas bombas peristálticas com vazão controlada para 1L/h. Cada bomba conectava-se a dois filtros de laboratório de areia (FLA), que se acoplavam a duas colunas de CAG, CC1 e CC2, com carvão de granulometrias distintas. O sistema foi monitorado durante 48h. Os resultados dos ensaios de coagulação mostraram boa eficiência de remoção (> 50 %) para água de estudo (AE) com pH natural da água (7,6), para uma dosagem de sulfato de alumínio de 25mg/L , tanto em termos de turbidez quanto de cor verdadeira remanescentes. Para os ensaios com polímeros sintéticos, o polímero catiônico, em geral, se destacou em relação ao polímero aniônico com percentuais médios de remoção de 57% para remoção de cor verdadeira. Quando avaliada a representabilidade dos dados, observou-se que as eficiências de remoções não se repetiram. Na terceira etapa, houve baixa remoção saxitoxina por parte tratamento convencional (7%), a remoção se processou nas colunas de adsorção. A CC1 e a CC2 obteram remoções entre 100 e 70%, entretanto, para percentuais máximos de remoção a CC2 removeu maior quantidade de saxitoxina por unidade de tempo em relação a CC1, praticamente seis horas de diferença. As isotermas de Freundlich e Langmuir para as amostras de carvão ativado avaliadas aprestaram melhores ajustes para a CC2.
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Rindfuss, Elaine. "Pyrodinium cysts in manatee stomach contents : harmless tourists or Trojan horses?" Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-137570.

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First described by Plate (1906), Pyrodinium bahamense is a bioluminescent dinoflagellate species which forms a resting cyst as part of its life cycle.  P. bahamense forms large dense cyst beds in the flocculent layer of sediments and can remain dormant for decades before excysting and forming blooms.  The Atlantic strain has recently been discovered to produce a neurotoxin called saxitoxin.  Although saxitoxins are most commonly associated with paralytic shellfish poisoning, saxitoxin produced by P. bahamense has been implicated in a number of human illnesses following the consumption of contaminated puffer fish originating from the Indian River Lagoon, Florida.  The discovery of P. bahamense cysts on seagrass blades during an ongoing bloom raised the question of whether manatees, whose diet is composed mainly of seagrass, could be at risk of exposure to saxitoxins.  The aim of this study was to determine whether P. bahamense cysts can be digested in the manatee gastrointestinal tract or if they would pass through intact.  There are no known methods for purifying P. bahamense cysts from the contents of the manatee gastrointestinal tract, so it was necessary to develop an appropriate protocol using cysts purified from sediments in Tampa Bay, Florida.  These methods were then to be used to test whether P. bahamense cysts added to manatee digesta break down over time, and also to test archived digesta samples for presence of cysts.  A successful method for purifying cysts from manatee digesta could not be developed during the span of this study, and so no conclusions could be drawn about the likelihood of digestion.  However, archived samples were found to contain P. bahamense cysts, confirming that manatees are ingesting them while feeding.
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Taroncher, Oldenburg Gaspar 1968. "Cell cycle dynamics and the physiology of saxitoxin biosynthesis in Alexandrium fundyense (dinophyceae)." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50371.

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Nauman, Callie A. "The Spatial and Temporal Distribution and Environmental Drivers of Saxitoxin in Northwest Ohio." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1589644025246293.

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Vargas, Sarah Regina. "Influência da concentração de nutrientes na interação entre duas espécies fitoplanctônicas isoladas do Reservatório de Itupararanga - SP." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-03052012-160408/.

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O Reservatório de Itupararanga, no interior do estado de São Paulo, tem como principal finalidade geração de energia elétrica e o abastecimento público, além de área de lazer e pesca. O crescimento urbano e agrícola em torno do corpo hídrico tem alterado a qualidade da água favorecendo a proliferação de cianobactérias. Estudos preliminares da comunidade fitoplanctônica demonstraram a dominância da cianofícea Cylindrospermopsis raciborskii e da clorofícea Monoraphidium contortum. Com o objetivo de investigar o nível trófico do reservatório e sua influência na dominância destas espécies, foram realizados ensaios de interação entre estes microrganismos sob diferentes concentrações de fósforo, simulando o reservatório em três diferentes níveis tróficos: oligotrófico, mesotrófico e supereutrófico. Também foi determinada a produção de saxitoxina pela cianobactéria. No ambiente oligotrófico a C. raciborskii apresentou diminuição do volume celular, aumento da produção de saxitoxina e senescência em interação com o M. contortum. Nos ambientes mesotrófico e supereutrófico, a cianobactéria não apresentou diferenças no crescimento e na produção de saxitoxina, comparado ao seu controle, quando em interação com a clorofícea. O mesmo não foi observado para M. contortum nestes dois níveis de trofia, pois teve seu crescimento prejudicado nas interações com C. raciborskii. As velocidades específicas de crescimento de M. contortum foram crescentes conforme o aumento da trofia, e as da C. raciborskii decrescentes. As concentrações de clorofila-a também foram crescentes conforme o aumento de trofia, e diminuíram no final dos experimentos. O consumo de ortofosfato foi semelhante na simulação dos três ambientes e o consumo do nitrato, foi maior quanto mais elevado o nível trófico. A partir dos resultados, foram feitas previsões das espécies fitoplanctônicas dominantes regidas pelo nível trófico do reservatório, que contribuirão nas medidas de conservação e manejo deste ecossistema aquático.
The Reservoir Itupararanga within the state of São Paulo, whose main purpose is public supply, besides electricity generation, and recreational areas and fishing. The urban growth and agriculture around the water body has changed its quality, favoring the growth of cyanobacteria. Preliminary studies of phytoplankton showed a dominance of cyanophyceae Cylindrospermopsis raciborskii and clorofícea Monoraphidium contortum. In order to investigate the trophic level of the reservoir and its influence on the dominance of these species, tests of the interaction between these microorganisms under different phosphorus concentrations were performed, simulating the reservoir in three different trophic levels: oligotrophic, mesotrophic and supereutrophic. The production of saxitoxin by the cyanobacteria was also defined. In the oligotrophic C. raciborskii showed a decrease of cell volume, increased production of saxitoxin and senescence in interaction with M. contortum. In mesotrophic and supereutrofic environments, the cyanobacteria did not show differences in growth and production of saxitoxin, compared to their control when interacting with the chlorophycea. The same was not observed for M. contortum in these two trophic levels, as its growth was affected by the interactions with C. raciborskii. The specific growth rates of M. contortum were growing with increasing trophic, and those of C. raciborskii decreasing. The chlorophyll-a concentrations were also growing with increasing trophic, and decreased at the end of the experiments. The orthophosphate consumption was similar in the three simulation environments and consumption of nitrate was greater the higher the trophic level. From the results, were made estimates of the dominant phytoplankton species was governed by the trophic level of the reservoir, which will help in the conservation and management of this aquatic ecosystem.
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Books on the topic "Saxitoxin"

1

Oldenburg, Gaspar Taroncher. Cell cycle dynamics and the physiology of saxitoxin biosynthesis in Alexandrium fundyense (Dinophyceae). Woods Hole, Mass: Woods Hole Oceanographic Institution, 1998.

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2

Y, Kao C., Levinson S. R, and New York Academy of Sciences., eds. Tetrodotoxin, saxitoxin, and the molecular biology of the sodium channel. New York, N.Y: New York Academy of Sciences, 1986.

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Nakagawa, Kazuma. Neurological Effects of Marine Toxins. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199937837.003.0178.

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Human ingestion of marine toxins can produce various neurological effects, often involving the voltage-gated Na+ channels that are critical for action potential generation and propagation. Diagnosis for most marine neurotoxin is made clinically, and thus recognizing the signs and symptoms of each toxin, and obtaining the appropriate history, is essential. Major marine neurotoxins-tetrodotoxin, saxitoxin, ciguatoxin, brevetoxin, and domoic acid, have a distinct mechanism and clinical manifestation.
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Kiel, Universität, ed. Einfluss von Natrium- und Lithium-Ionen auf die Blockade von Natrium-Kanälen der Nervenmembran durch Tetrodotoxin und Saxitoxin. Kiel, 1990.

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Leung, Doris G. Neuropathies Associated with Infection or Toxic Exposure. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199937837.003.0113.

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Among the many causes of peripheral neuropathy are those mediated by environmental exposure to infectious and toxic agents. The most common neuropathy associated with HIV is HIV-associated distal sensory polyneuropathy (HIV-DSP). The clinical presentation of HIV-DSP is one of a distal, symmetric, often painful, small-fiber sensory axonal polyneuropathy. Other infectious causes of neuropathy include hepatitis C, leprosy, Lyme disease, rabies, and diphtheria, and antibiotic drugs such as isoniazid can also cause neuropathy. Heavy metals and a variety of other toxins including chemotherapeutic agents such as platinum, vincristine, and thalidomide disrupt peripheral nerve function. High doses of pyridoxine can cause damage to the dorsal root ganglia and foodbourne toxins such as saxitoxins found in shellfish.
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Book chapters on the topic "Saxitoxin"

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Ballot, Andreas, Cécile Bernard, and Jutta Fastner. "Saxitoxin and Analogues." In Handbook of Cyanobacterial Monitoring and Cyanotoxin Analysis, 148–54. Chichester, UK: John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781119068761.ch14.

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Pearson, Leanne Andrea, and Brett Anthony Neilan. "Saxitoxin and Related Paralytic Shellfish Toxins." In Handbook of Foodborne Diseases, 1045–55. Boca Raton : Taylor & Francis, [2019] | Series: Food microbiology series | “A CRC title, part of the Taylor & Francis imprint, a member of the Taylor & Francis Group, the academic division of T&F Informa plc.”: CRC Press, 2018. http://dx.doi.org/10.1201/b22030-98.

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Suarez-Isla, Benjamin A. "Saxitoxin and Other Paralytic Toxins: Toxicological Profile." In Marine and Freshwater Toxins, 23–41. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-007-6419-4_25.

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Suarez-Isla, Benjamin A. "Saxitoxin and Other Paralytic Toxins: Toxicological Profile." In Marine and Freshwater Toxins, 1–16. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-007-6650-1_25-1.

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McGrath, Sara C., and Jonathan R. Deeds. "Determination of Saxitoxin and Tetrodotoxin in Fish." In Analysis of Food Toxins and Toxicants, 403–30. Chichester, UK: John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781118992685.ch13.

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Botana, Luis M., Amparo Alfonso, Mercedes R. Vieytes, M. Carmen Louzao, Ana M. Botana, Carmen Vale, and Natalia Vilariño. "Determination of Saxitoxin, Tetrodotoxin and Common Phycotoxins." In Analysis of Food Toxins and Toxicants, 431–68. Chichester, UK: John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781118992685.ch14.

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Trainer, Vera L., and Mark A. Poli. "Assays for Dinoflagellate Toxins, Specifically Brevetoxin, Ciguatoxin, and Saxitoxin." In Animal Toxins, 1–19. Basel: Birkhäuser Basel, 2000. http://dx.doi.org/10.1007/978-3-0348-8466-2_1.

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Zhou, Zhongkun, Yunhao Ma, Yuqing Niu, Juan Lu, Lixue Tu, and Peng Chen. "qPCR Assay in sxtA Gene in Saxitoxin-Producing Cyanobacteria." In Protocols for Cyanobacteria Sampling and Detection of Cyanotoxin, 397–402. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-4514-6_54.

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Imhof, Lutz, and Wido Schmidt. "Extraction and Chemical Analysis of Saxitoxin and Analogues in Water." In Handbook of Cyanobacterial Monitoring and Cyanotoxin Analysis, 418–31. Chichester, UK: John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781119068761.ch52.

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Hall, Sherwood, Gary Strichartz, E. Moczydlowski, A. Ravindran, and P. B. Reichardt. "The Saxitoxins." In Marine Toxins, 29–65. Washington, DC: American Chemical Society, 1990. http://dx.doi.org/10.1021/bk-1990-0418.ch003.

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Conference papers on the topic "Saxitoxin"

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Álvarez, Mercedes, Manuel Lolo, and Álvaro Antelo. "Computational Model of Adsorption for Hydroxybenzoate Saxitoxin Derivatives (GCs) on Graphene Surface." In ECSOC 2023. Basel Switzerland: MDPI, 2023. http://dx.doi.org/10.3390/ecsoc-27-16038.

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Wark, M., B. Kalanyan, L. Ellis, J. Fick, L. Connell, D. Neivandt, and J. F. Vetelino. "P0-9 A Lateral Field Excited Acoustic Wave Sensor for the Detection of Saxitoxin in Water." In 2007 IEEE Ultrasonics Symposium. IEEE, 2007. http://dx.doi.org/10.1109/ultsym.2007.306.

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Li, Ji, and Yong J. Yuan. "Notice of Retraction: Surface Plasmon Resonance Detection of Saxitoxin: An Alternative to In-Situ Monitoring Red-Tide Toxins." In 2011 Third Pacific-Asia Conference on Circuits, Communications and System (PACCS). IEEE, 2011. http://dx.doi.org/10.1109/paccs.2011.5990278.

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Gibson, Michael, Tom Byl, and Champagne Cunningham. "PRELIMINARY RESULTS OF MICROCYSTIN (MT) AND SAXITOXIN (SXT) PRESERVATION IN FOSSIL MOLLUSKS OF THE LATE CRETACEOUS COON CREEK FORMATION LAGERSTÄTTE: IMPLICATIONS FOR A KILL MECHANISM PRODUCING POSSIBLE MARINE REPTILE DEADFALLS." In Joint 56th Annual North-Central/ 71st Annual Southeastern Section Meeting - 2022. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022nc-376113.

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Teneva, Ivanka, Dzhemal Moten, Detelina Belkinova, Tsvetelina Mladenova, and Balik Dzhambazov. "TOXIC POTENTIAL OF ANABAENOPSIS ELENKINII (CYANOBACTERIA) ISOLATED FROM A BLOOM IN LAKE VAYA (BULGARIA)." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/5.1/s20.36.

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Cyanobacteria are ancient photosynthetic organisms that under certain conditions (high temperature, eutrophication) can grow rapidly and form "cyanobacterial blooms". Very often, these blooms are accompanied by production of cyanotoxins, which in most cases are dangerous to the other organisms. Knowing the producers of cyanotoxins is of utmost importance, especially today when climate change has been shown to increase the frequency of toxic cyanobacterial blooms worldwide. The aim of the present study was to characterize the toxic potential of the cyanobacterium Anabaenopsis elenkinii V.V.Miller 1923 isolated from Lake Vaia during a cyanobacterial bloom. The isolated strain (Anabaenopsis elenkinii) was identified based on a morphological analysis using light microscopy, and its taxonomic affiliation and phylogenetic position were confirmed by applying the Maximum Likelihood (ML) method for phylogenetic analysis based on the 16S rDNA sequence. The production of cyanotoxins was analyzed by applying immunological methods (ELISA) for detection of microcystins, cylindrospermopsin and saxitoxins. The toxic potential of Anabaenopsis elenkinii was evaluated in vitro by methyl-thiazole-tetrazolium (MTT) cytotoxicity and superoxide dismutase (SOD) activity assays using HT-29 cells. Our analyzes indicated that Anabaenopsis elenkinii produces microcystins (0.42 ng/mL), cylindrospermopsin (0.10 ng/mL) and saxithixins (0.05 ng/mL). The MTT cytotoxicity assay showed that the medium, in which the cyanobacterial strain was grown, significantly reduced the viability of HT-29 cells and this effect was dose- and time-dependent. In addition, 50% inhibition of the SOD activity was also observed. This is the first report of Anabaenopsis elenkinii as a producer of cyanotoxins. Our results provide valuable information about the toxin-producing cyanobacteria. They demonstrate the potential danger of "cyanobacterial blooms" where Anabaenopsis elenkinii is a dominant species.
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Reports on the topic "Saxitoxin"

1

Kao, C. Y. Site-Specific Antagonists to Tetrodotoxin and Saxitoxin. Fort Belvoir, VA: Defense Technical Information Center, May 1988. http://dx.doi.org/10.21236/adb124671.

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Kao, C. Y. Site-Specific Antagonists to Tetrodotoxin and Saxitoxin. Fort Belvoir, VA: Defense Technical Information Center, May 1990. http://dx.doi.org/10.21236/adb145447.

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Mirocha, Chester J., Young B. Kim, Urooj Mirza, Weiping Xie, and Hamed K. Abbas. Analysis of Saxitoxin from Urine Using Dynamic FAB/MS. Fort Belvoir, VA: Defense Technical Information Center, October 1991. http://dx.doi.org/10.21236/ada244960.

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Mirocha, Chester J., Won J. Cheong, and Hamed Abbas. Analysis of Saxitoxin from Urine Using Dynamic FAB/MS. Fort Belvoir, VA: Defense Technical Information Center, July 1990. http://dx.doi.org/10.21236/ada226474.

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5

Maycock, Barry, Cath Mulholland, Emma French, and Joseph Shavila. Rapid Risk Assessment: What is the risk from microcystins in the edible flesh of fish caught from Lough Neagh? Food Standards Agency, March 2024. http://dx.doi.org/10.46756/sci.fsa.slz868.

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During the Summer and Autumn of 2023, Lough Neagh in Northern Ireland was affected by a cyanobacterial bloom. Testing of water from within the bloom reported high concentrations of one type of cyanobacterial toxin, microcystins. Samples were taken from the Lough of eels, roach, perch, pollan and bream and tested for a range of cyanobacterial toxins, including microcystins, nodularins, anatoxin, cylindrospermopsin and saxitoxin. Each sample comprised 10 fish, and five samples were taken of each species, except for bream for which a single sample was collected. The fish were dissected and the edible flesh, intestine, liver, roe, gonad and/or gills analysed separately. Microcystins were detected at a range of concentrations in the various parts of the fish that were sampled - intestine, liver, roe and/or gills, but were not detected in the edible flesh of any of the fish samples. Averaged across the samples, the highest concentrations of microcystins were quantified in the intestine samples, followed by the liver samples, with low concentrations were detected in the gills and a small number of the samples of gonads and roe. None of the other toxins were detected in any fish sample. The initial analysis for microcystins was of free toxins only. However, there is evidence that microcystins which are covalently bound to proteins are also bioavailable and therefore 22 fish tissue samples, including nine fish flesh samples, were also sent to another laboratory where they were analysed by a method which measures the total concentrations of microcystins, free and protein-bound. The viscera tissue samples chosen for the further analysis were those with the highest concentrations of the free toxins, while the fish flesh samples included 2-3 samples each of eels, roach, pollan and perch. The concentrations of total microcystins found in viscera samples were around one order of magnitude higher than the concentrations of free microcystins that had been measured. However, microcystins were still not detected in the edible fish flesh samples. It is possible that microcystins were not present at any level in any of the fish flesh samples. However, the presence of microcystins in the edible flesh of fish has been reported in the scientific literature, albeit at lower levels than those in the gastrointestinal tract or other parts of the viscera such as liver (Testai et al., 2016). Since microcystins were detected in other parts of the fish sampled from Lough Neagh it is also possible that they were also present in the fish flesh but at levels below the limits of detection of the analytical methods. The limit of detection of the analytical method for total (free + bound) microcystins was 10 µg/kg wet weight. An upper bound dietary exposure assessment was conducted. While a lower bound exposure assessment would assume the microcystins were not present in the edible flesh, i.e. a concentration of 0 µg/kg, the upper bound approach assumed they were present at the limit of detection of 10 µg/kg. The true concentrations may be between these levels. The exposure assessments consider high consumers of fish (97.5th percentile). For eels, consumption data were used from the National Diet and Nutrition Survey (NDNS). For roach, perch, pollan and bream. No consumption data were available from the NDNS and consumption data for trout were used instead as a proxy. The main target organ for toxicity of the microcystins is the liver, though other organs may also be affected. The microcystin most studied toxicologically is microcystin-LR, which is one of the most common microcystins. A WHO review established a provisional tolerable daily intake (TDI) for microcystin-LR of 0.04 µg per kg bodyweight (bw). WHO recommended that exposures to total microcystins should be compared to this provisional TDI, though there is uncertainty with this as individual microcystins are likely to differ significantly in their toxic potencies. Estimated dietary exposures of total microcystins were all within the provisional TDI, indicating no health concern from consuming the edible flesh of these species. Since fish may be caught and prepared for consumption not only by food business operators but by recreational anglers, concern has been raised that evisceration may be incomplete or the edible flesh may become contaminated in the process, and therefore this was also considered in the risk assessment. This was based on the sample of fish which contained the highest concentration of total microcystins in a viscera component, which was a sample of roach with a particularly high concentration of microcystins in intestine. It was assumed that 10% of the relative proportion of intestine to flesh in the fish would be inadvertently consumed with the flesh. In this scenario, dietary exposures would be within the provisional TDI in most age groups or would marginally exceed the TDI, but this would not be toxicologically significant. In addition, since this exposure scenario used an upper bound approach to the concentration in flesh, and used the highest concentration in any viscera sample, it is not clear that there would be any exceedance of the provisional TDI in practice. Overall, it appears unlikely that consumers will substantially exceed the provisional TDI on a long-term basis due to incomplete evisceration of fish. Overall, exposure to microcystins from eating the edible flesh of the tested fish species would not be expected to cause adverse effects in consumers, including if the fish is inadequately eviscerated. Therefore, we consider the frequency of adverse reactions in the general population to be negligible, so rare that it does not merit to be included. Based on the possible levels of exposure to microcystins from fish from Lough Neagh, it is considered that any liver injury, were it to occur in consumers of fish, would result from long term exposure and be mild. Overall, we consider the severity of illness that could potentially occur as a result of exposure to microcystins from consuming edible fish flesh from Lough Neagh to be medium (i.e. moderate illness, incapacitating but not usually life-threatening and of moderate duration). We consider the level of uncertainty to be medium (i.e. there are some but no complete data available), but that this does not affect the conclusion of the risk assessment since many of the key uncertainties are addressed within the risk assessment. However, future monitoring would be useful to assess whether microcystin concentrations in the fish change over time.
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Bering Strait: Walruses and Saxitoxin—late summer/fall 2017. Alaska Sea Grant, November 2017. http://dx.doi.org/10.4027/bsws.2017.

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Alexandrium algae, saxitoxin, and clams: Bering Strait and Chukchi Sea 2018–2019. Alaska Sea Grant, November 2019. http://dx.doi.org/10.4027/aascbscs.2019.

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