Investigation of the Occurrence of Cyanotoxins in Lake Karaoun (Lebanon) by Mass Spectrometry, Bioassays and Molecular Methods (original) (raw)
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Occurrence and diversity of cyanotoxins in Greek lakes
Scientific Reports
Toxic cyanobacteria occur in Greek surface water bodies. However, studies on the occurrence of cyanotoxins (CTs) are often limited to mainly microcystins (MCs), with use of screening methods, such as ELISA, that are not conclusive of the chemical structure of the CT variants and can be subject to false positive results. A multi-lake survey in Greece (14 lakes) was conducted in water and biomass, targeted to a wide range of multi-class CTs including MCs, nodularin-R (NOD), cylindrospermopsin (CYN), anatoxin-a (ANA-a) and saxitoxins (STXs), using multi-class/variant LC-MS/MS analytical workflows, achieving sensitive detection, definitive identification and accurate quantitation. A wide variety of CTs (CYN, ANA-a, STX, neoSTX, dmMC-RR, MC-RR, MC-YR, MC-HtyR, dm 3 MC-LR, MC-LR, MC-HilR, MC-WR, MC-LA, MC-LY, MC-LW and MC-LF), were detected, with MCs being the most commonly occurring. In biomass, MC-RR was the most abundant toxin, reaching 754 ng mg −1 dw, followed by MC-LR (458 ng mg −1 dw). CYN and ANA-a were detected for the first time in the biomass of Greek lakes at low concentrations and STXs in lakes Trichonis, Vistonis and Petron. The abundance and diversity of CTs were also evaluated in relation to recreational health risks, in a case study with a proven history of MCs (Lake Kastoria). Cyanobacteria are photosynthetic prokaryotic organisms, which can rapidly multiply, forming "blooms" in water 1,2. They are known to produce various metabolites of diverse and mostly unknown function 3,4 as well as potent toxins, called cyanotoxins (CTs) 5-8. CTs are compounds with diverse structures and biosynthetic origin (alkaloid, heterocyclic, peptide, aminoacids, etc) 6,7,9,10 with various modes of toxicity (e.g. hepatotoxic, dermatotoxic, neurotoxic, cytotoxic) 11,12. They are therefore, potentially harmful to humans and other organisms 13-16 , posing a significant ecological risk to aquatic habitats and to public health 2,17,18. Microcystins (MCs) are the most widespread class of CTs detected in fresh waters 9. They are cyclic heptapeptides (Fig. S1) containing the unusual β-amino acid ADDA ((2 S,3 S,8 S,9 S)−3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl deca-4,6-dienoic acid) which is responsible for their toxicity due to its conjugated diene, the cyclic structure and the non-esterified Glu residue 19-21. MCs are known to be hepatotoxic. They mainly mediate their toxicity by uptake into hepatocytes, followed by inhibition of protein phosphatases (PPs), which are able to dephosphorylate serine and threonine residues. Inhibition of PPs results in an increased phosphorylation of proteins in liver cells, significantly affecting metabolic pathways, membrane transport, secretion, etc. 19. At sub-lethal doses MCs are also known to be potent liver tumor promoters 22 and produce oxidative DNA damage 23,24. Up to now, over 248 MC variants have been identified and structurally characterized 25,26. Nodularins (NODs) are pentapeptides with similar structure with MCs. Ten variants have been identified so far, among which Nodularin-R (NOD) is the most frequently found 25,27,28. Cylindrospermopsin (CYN) is an alkaloid cyanotoxin (Fig. S1) of rising environmental concern, due to its multiple toxicity endpoints, frequency of occurrence and severity of health impacts 29,30. CYN is mainly hepatotoxic, but potential effects also include genotoxicity, dermatotoxicity, fetal toxicity and cytotoxicity 29-31. Unlike other CTs (MCs, NODs) that are mostly intracellular in viable cells, CYN is found mostly as extracellular 32. Anatoxin-a (ANA-a) is a secondary, bicyclic amine alkaloid (Fig. S1), which is highly water-soluble, presenting increased neurotoxicity 33,34. The (+) entantiomer, which is toxicologically active, has been associated with a number of animal fatalities, including cattle, dogs, bats, pigeons and flamingos 35-37. Saxitoxins (STXs), also known as Paralytic Shellfish Poisoning toxins (PSPs), are relatively
2017
Dayet-Aaoua lake (DA) is a freshwater aquatic ecosystem of ecological interest, located at a middle Atlas mountains under humid hydrographic basin (Ifran, Morocco) (33° 39′ 10′′ N, 5° 02′ 30′′ W). This work deals on the toxicity assessment of Microcystis aeruginosa strain isolated from DA lake, using both Artemia bioassay and the highperformance liquid chromatography (HPLC) equipment provided with a photodiode array detector (PDA. HPLC-PDA identification and quantification of hepatotoxins cyanotoxins (Microcystins). The toxicity of the cultural Microcystis biomass evaluated by Artemia bioassay revealed a positive letal concentions (LC) (24-h LC50 = 9.01 mg mL -1 and 40-h LC50 = 6.87 mg mL -1 ). Microcystins (MC) variants selected by HPLC-PDA showed a high MC content concentration (185.56 μg g -1 Dry weight) which confirmed the toxicity assessed. Four MC variants were clearly identified in the DA biomass (MC-WR, MCRR, DM-WR, MCYR). For the first time in this natural lake, the obtaine...
Environmental Monitoring and Assessment, 2010
Mansour Eddahbi (MED) (30°55′N, 6°53′W) and Almassira (ALM) (31°95′N, 6°72′W) are two Moroccan lake reservoirs located at an arid and semi-arid hydrographic basin, respectively. Both are used for irrigation, recreational activities and drinking-water production. This paper deals with the characterization and quantification of microcystins (MC) from two Microcystis aeruginosa blooms occurring in those reservoirs. The toxicity of the blooms was confirmed and evaluated by both mouse and Artemia bioassays. The calculated LD50 values revealed that the MED bloom had a medium toxicity (LD50 = 358 mg kg − 1 body weight), whereas the ALM bloom had low toxicity (LD50 = 829 mg kg − 1 body weight). The 24-h LC50 values were 1.88 and 4.15 mg ml − 1 for the MED and ALM blooms, respectively, using Artemia assay. The identification and quantification of MC variants were carried out by high performance liquid chromatography (HPLC) equipped with a photodiode array detector, and HPLC coupled to mass spectrometry. The MC content, as Microcystin-LR (MC-LR) equivalents, was higher in the MED bloom (64.4 μg g − 1 dry weight) than in the ALM bloom (9.9 μg g − 1 dry weight). Five MC variants were identified in the MED cyanobacteria bloom (MC-RR, MC-YR, MC-LR, MC-FR, and MC-WR) and only one (MC-LR) in the ALM bloom. The results show that the occurrence of toxic cyanobacteria blooms in the studied reservoirs may be regarded as a health hazard; therefore, cyanotoxin monitoring in them is highly recommended.
Environmental Monitoring and Assessment, 2021
recorded in July (2,822,000 cells/mL). The species present were Aphanizomenon flos-aquae, Microcystis flos-aquae, Microcystis wesenbergii, Cuspidothrix issatschenkoi, Dolichospermum flos-aquae, and Snowella litoralis. In July and September, the microcystin encoding gene mcyE and the saxitoxin encoding gene sxtG were amplified in the biomass samples. While a low concentration of microcystin-RR was found in one water sample from July, analyses of Abramis brama and Carassius gibelio caught from the reservoir did not show the presence of the investigated microcystins in the fish tissue. However, several histopathological changes, predominantly in gills and kidneys, were observed in the fish, and the Abstract Cyanobacteria are important members of lake plankton, but they have the ability to form blooms and produce cyanotoxins and thus cause a number of adverse effects. Freshwater ecosystems around the world have been investigated for the distribution of cyanobacteria and their toxins and the effects they have on the ecosystems. Similar research was performed on the Fehérvárcsurgó reservoir in Hungary during 2018. Cyanobacteria were present and blooming, and the highest abundance was Highlights • Cyanobacterial blooms and cyanotoxins are common worldwide, thus, monitoring and data on their adverse effects are required • Six cyanobacterial species were present and blooming in Fehérvárcsurgó reservoir during 2018, a previously unexplored site in Hungary • Microcystin (mcyE) and the saxitoxin (sxtG) encoding genes were detected in the biomass, and microcystin-RR was found in one sample • Microcystins were not detected in fish tissue, but histopathological alterations in gills and kidneys were observed
2014
Cyanobacteria species are distributed worldwide and extensive growth can result in cyanotoxin production, hypoxic zones, human health risk, and mortality of fish, domesticated animals, invertebrates, and plants. Better analytical tools can help water quality managers and regulatory agencies assess and manage cyanobacteria and cyanotoxin abundance to reduce environmental and health risk. This study determined the presence and relative abundance of 4 potentially toxic cyanobacteria taxa (Microcystis aeruginosa, Cylindrospermopsis raciborskii, Lyngbya wollei, and Aphanizomenon/ Anabaena spp.), total cyanobacteria, and three toxin genes (microcystin mcyH+/A-, cylindrospermopsin PKS, and anatoxin PKS) using qPCR, and concentrations of microcystin and cylindrospermopsins in selected samples using ELISA assays. All species were found in all lakes, but abundance of individual taxa SSU rDNA and toxin genes differed among lakes. Microcystins were found at low levels (=0.31ppb) in 4 of the 6 l...
Depth profiles of cyanobacterial hepatotoxins (microcystins) in three Turkish freshwater lakes
Hydrobiologia, 2003
The Turkish freshwater lakes, Sapanca, Iznik and Taskisi (Calticak) have been enriched with nutrients from agriculture and domestic sources for many years. A major bloom of cyanobacteria (blue-green algae) in Lake Sapanca was recorded in May 1997, closely followed by a fish kill. Investigations were subsequently made on the cyanobacteria and water quality of the lakes, including analysis for cyanobacterial hepatotoxins (microcystins) in the filtered particulate fraction. Samples, taken from the beginning of May to end of August 1998, were analysed for microcystins by high–performance liquid chromatography with photodiode array detection (HPLC-PDA), protein phosphatase inhibition assay (PPIA) and an enzyme-linked immunosorbent assay (ELISA). No microcystins were detected in the water column in Lake Sapanca above 10 m, but toxins were found in filtered cyanobacterial samples from 20 m depth at a concentration of 3.65 μg l−1 microcystin–LR equivalents. Ninety percent of the microcystin pool detected in L. Sapanca was found between depths of 15 and 25 m. The principal microcystin detected by HPLC-PDA was similar to microcystin–RR. Two unidentified microcystin variants were found in Lake Taskisi surface samples at a concentration of 2.43 μg l−1 microcystin–LR equivalents in the filtered cyanobacterial cell fraction. Although 10 water samples (10 × 5 l) were taken from Lake Iznik (surface to 20 m, 5 m intervals), no microcystins were detected by HPLC-PDA (limit of detection 10 ng). The depth at which microcystins were detected in L. Sapanca coincided with the draw-off depth for the drinking water supply for the city of Sakarya
Hydrobiologia, 2014
The Macau storage reservoir (MSR) has experienced algal blooms in recent years, with high levels of Cylindrospermopsis and Microcystis and detectable concentrations of cyanotoxins. To analyze the cyanotoxin-producing genotypes and relate the corresponding cyanotoxins to the water quality parameters, a quantitative real-time polymerase chain reaction was developed and applied to the water samples in three locations of MSR. Cylindrospermopsin polyketide synthetase (pks) gene and a series of microcystin synthetase (mcy) genes were used for identifying and quantifying cylindrospermopsin-and microcystin-producing genes, and the corresponding water parameters were measured accordingly. Our results showed that high concentrations of cylindrospermopsin and low concentrations of microcystin were measured during the study period. There was a strong correlation between the pks gene numbers and cylindrospermopsin concentrations (R 2 = 0.95), while weak correlations were obtained between the mcy genes numbers and microcystin concentrations. Furthermore, the pks gene numbers were strongly related to Cylindrospermopsis (R 2 = 0.88), cyanobacterial cell numbers (R 2 = 0.96), total algae numbers (R 2 = 0.95), and chlorophyll-a concentrations (R 2 = 0.83), consistent with the dominant species of Cylindrospermopsis among the cyanobacteria existing in MSR. NH 4 -N (R 2 = 0.68) and pH (R 2 = 0.89) were the water quality parameters most highly correlated with the pks gene numbers. These results contribute to monitoring for potential cyanotoxins in raw water.