Seasonal variation of microcystin concentrations in the Saint-Caprais reservoir (France) and their removal in a small full-scale treatment plant

Maatouk, Imed; Bouaı̈cha, Noureddine; Fontan, Didier; Lévi, Yves

doi:10.1016/s0043-1354(01)00507-3

Cited by 48 publications

(23 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For the PP2A inhibition assay, 3-g MCYST-LR equivalents of [D-Asp]MCYST-RR and [DMAdda, D-Asp]MCYST-RR were purified by HPLC as described above. The two samples were dissolved in 1 ml of 50% aqueous methanol and analyzed three times with PP2A after a 20-fold dilution in 50% aqueous methanol (22).…”

Section: Methodsmentioning

confidence: 99%

Microcystin Biosynthesis in Planktothrix : Genes, Evolution, and Manipulation

Christiansen

Fastner

Erhard³

et al. 2003

J Bacteriol

326

273

View full text Add to dashboard Cite

Microcystins represent an extraordinarily large family of cyclic heptapeptide toxins that are nonribosomally synthesized by various cyanobacteria. Microcystins specifically inhibit the eukaryotic protein phosphatases 1 and 2A. Their outstanding variability makes them particularly useful for studies on the evolution of structurefunction relationships in peptide synthetases and their genes. Analyses of microcystin synthetase genes provide valuable clues for the potential and limits of combinatorial biosynthesis. We have sequenced and analyzed 55.6 kb of the potential microcystin synthetase gene (mcy) cluster from the filamentous cyanobacterium Planktothrix agardhii CYA 126. The cluster contains genes for peptide synthetases (mcyABC), polyketide synthases (PKSs; mcyD), chimeric enzymes composed of peptide synthetase and PKS modules (mcyEG), a putative thioesterase (mcyT), a putative ABC transporter (mcyH), and a putative peptide-modifying enzyme (mcyJ). The gene content and arrangement and the sequence of specific domains in the gene products differ from those of the mcy cluster in Microcystis, a unicellular cyanobacterium. The data suggest an evolution of mcy clusters from, rather than to, genes for nodularin (a related pentapeptide) biosynthesis. Our data do not support the idea of horizontal gene transfer of complete mcy gene clusters between the genera. We have established a protocol for stable genetic transformation of Planktothrix, a genus that is characterized by multicellular filaments exhibiting continuous motility. Targeted mutation of mcyJ revealed its function as a gene coding for a O-methyltransferase. The mutant cells produce a novel microcystin variant exhibiting reduced inhibitory activity toward protein phosphatases.Microcystins are cyclic heptapeptides and share the common structure cyclo(-Adda-D-Glu-Mdha-D-Ala-L-X-D-MeAsp-L-Z), where X and Z represent variable L-amino acids, Adda is 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid, D-MeAsp is 3-methylaspartic acid, and Mdha is N-methyldehydroalanine. More than 60 isoforms of microcystin have been described (Fig.

show abstract

Section: Methodsmentioning

confidence: 99%

Microcystin Biosynthesis in Planktothrix : Genes, Evolution, and Manipulation

Christiansen

Fastner

Erhard³

et al. 2003

J Bacteriol

326

273

View full text Add to dashboard Cite

show abstract

“…Maatouk et al (2002) assumed that a mono-specific Aph. flosaquae bloom was responsible for the microcystin content of a Aph.…”

Section: Specific Health Risks From Contaminated Food and Cyanobactermentioning

confidence: 99%

Toxin mixture in cyanobacterial blooms – a critical comparison of reality with current procedures employed in human health risk assessment

Dietrich¹,

Fischer²,

Michel³

et al.

Advances in Experimental Medicine and Biology

View full text Add to dashboard Cite

Cyanobacteria are the oldest life forms on earth known to produce a broad spectrum of secondary metabolites. The functions/advantages of most of these secondary metabolites (peptides and alkaloids) are unknown, however, some of them have adverse effects in humans and wildlife, especially when ingested, inhaled or upon dermal exposure. Surprisingly, some of these cyanobacteria are ingested voluntarily. Indeed, for centuries mankind has used cyanobacteria as a protein source, primarily Spirulina species. However, recently also Aphanizomenon flos-aquae are used for the production of so called blue green algae supplements (BGAS), supposedly efficacious for treatment of various diseases and afflictions. Unfortunately, traces of neurotoxins and protein phosphatases (inhibiting compounds) have been detected in BGAS, making these health supplements a good example for human exposure to a mixture of cyanobacterial toxins in a complex matrix. The discussion of this and other possible exposure scenarios, e.g. drinking water, contact during recreational activity, or consumption of contaminated food, can provide insight into the question of whether or not our current risk assessment schemes for cyanobacterial blooms and the toxins contained therein suffice for protection of human health. Cyanobacterial metabolites: Health hazards for humans?Cyanobacteria exist worldwide ubiquitously, including in extreme environments (Hitzfeld et al.

show abstract

“…L'extrait est ensuite refiltré sur filtre GF/C et évaporé à sec à 40 °C. Le résidu sec est repris dans 1 mL de méthanol (MAATOUK et al, 2002 ).…”

Section: Détermination De La Concentration Des MC Dans L'eau Brute 2unclassified

Caractérisation biochimique et moléculaire d’efflorescences à cyanobactéries toxiques dans le réservoir Lalla Takerkoust (Maroc)

Ghazali

Saqrane

Saker³

et al. 2011

rseau

View full text Add to dashboard Cite

En complément aux travaux réalisés depuis 1994 sur la toxicologie des cyanobactéries dans différents lacs-réservoirs du Maroc, le présent travail se propose d'apporter des informations supplémentaires en se fixant trois principaux objectifs: 1) Mise à jour de la base de données de la variation temporelle des teneurs en cyanotoxines intracellulaires (microcystines) d'efflorescences cyanobactériennes fréquemment occasionnés dans le lac réservoir Lalla Takerkoust; 2) Évaluation de la contamination des eaux brutes du lac par les microcystines (MC) (quantification des MC extracellulaires); 3) Caractérisation de la diversité moléculaire des souches cyanobactériennes par la détection des gènes de la synthèse des cyanotoxines (MC) en utilisant les deux méthodes multiplex‑PCR et RFLP (Restriction Fragment Length Polymorphism). L'analyse par HPLC des échantillons 2005 et 2006 d'efflorescences cyanobactériennes a montré qu'il y a une variation qualitative et quantitative des microcystines intracellulaires (MC). L'évaluation des teneurs en MC et dissoutes dans l'eau brute, par ELISA, a révélé des quantités très importantes de MC extracellulaires avec un maximum de 95,4 μg•L‑1 durant le mois de décembre 2005 (phase de déclin du développement des cyanobactéries). En général, durant l'année, les concentrations des MC dissoutes restent toujours au‑dessus de la valeur guide recommandée par l'OMS pour l'eau de boisson (1 μg•L‑1). La caractérisation moléculaire, recherche du gène de synthèse des MC, a confirmé que seule Microcystis aeruginosa est la souche productrice des MC au sein de la fraction phytoplanctonique. Ce travail a pour mérite de confirmer pour la première fois au Maroc que, lors de proliférations d'efflorescences cyanobactériennes à Microcystis, les teneurs en MC dans les eaux brutes du lac sont si importantes qu'il est fortement recommandé de prendre en compte les divers risques sanitaires potentiellement engendrés par cette contamination lors de l'utilisation de cette eau (eau d'alimentation sans traitement, eau récréative, eau d'irrigation, etc.). D'après ces résultats, nous concluons que la mise en place d'un programme de surveillance des cyanobactéries et de contrôle des cyanotoxines (MC) doit être basée sur la caractérisation biochimique (détermination de la nature et de la quantité de toxines produites) et complémentée par la caractérisation génétique des souches potentiellement productrices de ces cyanotoxines.

show abstract

Seasonal variation of microcystin concentrations in the Saint-Caprais reservoir (France) and their removal in a small full-scale treatment plant

Cited by 48 publications

References 24 publications

Microcystin Biosynthesis in Planktothrix : Genes, Evolution, and Manipulation

Microcystin Biosynthesis in Planktothrix : Genes, Evolution, and Manipulation

Toxin mixture in cyanobacterial blooms – a critical comparison of reality with current procedures employed in human health risk assessment

Caractérisation biochimique et moléculaire d’efflorescences à cyanobactéries toxiques dans le réservoir Lalla Takerkoust (Maroc)

Contact Info

Product

Resources

About