SEARCH · PubMed Health

Results for “Microcystins”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed2006

Effects of nonylphenol on the growth and microcystin production of Microcystis strains.

Both organic pollution and eutrophication are prominent environmental issues concerning water pollution in the world. It is important to reveal the effects of organic pollutants on algal growth and toxin production for assessing ecological risk of organic pollution. Since nonylphenol (NP) is a kind of persistent organic pollutant with endocrine disruptive effect which exists ubiquitously in environments, NP was selected as test compound in our study to study the relationship between NP stress and Microcystis growth and microcystin production. Our study showed that responses of toxic and nontoxic Microcystis aeruginosa to NP stress were obviously different. The growth inhibition test with NP on M. aeruginosa yielded effect concentrations E(b)C(50) values within this range of 0.67-2.96 mg/L. The nontoxic M.aeruginosa strains were more resistant to NP than toxic strains at concentration above 1mg/L. Cell growth was enhanced by 0.02-0.2 mg/L NP for both toxic and nontoxic strains, suggesting a hormesis effect of NP on M. aeruginosa. Both toxic and nontoxic strains tended to be smaller with increasing NP. But with the increased duration of the experiment, both the cell size and the growth rate began to resume, suggesting a quick adaptation of M. aeruginosa to adverse stress. NP of 0.05-0.5 mg/L significantly promoted microcystin production of toxic strain PCC7820, suggesting that NP might affect microcystin production of some toxic M. aeruginosa in the field. Our study showed that microcystin excretion was species specific that up to 75% of microcystins in PCC7820 were released into solution, whereas >99% of microcystins in 562 remained in algal cells after 12 days' incubation. NP also significantly influenced microcystin release into cultural media. The fact that NP enhanced growth and toxin production of M. aeruginosa at low concentrations of 0.02-0.5 mg/L that might be possibly found in natural freshwaters implies that low concentration of NP may favor survival of M. aeruginosa in the field and may play a subtle role in affecting cyanobacterial blooms and microcystin production in natural waters.

Bacterial Proteins↗

PubMed2005

Detection of the cyanobacterial hepatotoxins microcystins.

Concern regarding the presence of microcystins in drinking water and their possible contamination in food (e.g., salad vegetables, fish, shellfish) has resulted in the need for reliable methods for the detection and accurate quantification of this class of toxins. Currently, routine analysis of microcystins is most commonly carried out using high-performance liquid chromatography with photodiode array detection (HPLC-PDA), although more sensitive biological assays such as antibody-based ELISAs and protein phosphatase inhibition assays have also proven useful. However, many of these methods have been hindered by the availability of a wide range of purified microcystins. Although over 60 variants have now been reported, only a very small number are commercially available and calibrated standards are not yet obtainable. This has led to the common practice of reporting microcystin-LR equivalence regardless of which variant is present. The increased availability of HPLC with online mass spectral analysis (HPLC-MS) may facilitate more accurate detection of toxin variants but as several microcystins share the same molecular mass, definitive identification can be difficult. A further difficulty in analyzing microcystins is the requirement for sample processing before analysis. Solid phase extraction (SPE) is typically used to enrich environmental concentrations of microcystins, or to eliminate contaminants from complex samples such as animal and plant tissues. Recently, new technologies employing recombinant antibodies and molecularly imprinted polymers have been exploited to develop assays and biosensors for microcystins. These novel detection systems are highly sensitive, often do not require sample processing, and offer a simpler, less expensive alternative to analytical techniques. They have also been successfully employed in solid phase extraction formats for the concentration and clean up of environmental samples before HPLC analysis.

Animals↗

PubMed2005

Genetic contributions to the risk assessment of microcystin in the environment.

Of the known toxins produced by cyanobacteria, microcystins and nodularins are the most significant threat to human and animal health. Knock-out studies have confirmed that microcystins are produced nonribosomally by a multienzyme complex consisting of peptide synthetases, polyketide synthases, and tailoring enzymes. Gene clusters for microcystin biosynthesis have been identified and sequenced in the distantly related cyanobacterial genera Microcystis, Planktothrix, and Anabaena. Homologous genes have been detected in a nodularin-producing Nodularia strain. Subsequently, microcystin biosynthesis (mcy) genes have been used to establish molecular techniques for the detection of toxigenic cyanobacteria in laboratory and field studies. mcy genes of unknown origin can be assigned to the producing species. Techniques are currently being developed for the quantification of mcy genes in field populations. These initial genetic investigations pave the way for a molecular monitoring of microcystin- and nodularin-producing cyanobacteria and for studying the dynamics of toxic cyanobacteria in lakes. Furthermore, microcystin-deficient mutants have significantly increased our knowledge about the impact of the toxins on Microcystis-Daphnia interactions. The experience gained on microcystin biosynthesis genes will be valuable for a risk assessment of microcystin in the environment and for future water management and lake-restoration strategies.

Animals↗

PubMed2004

Detection and analysis of the cyanobacterial peptide hepatotoxins microcystin and nodularin using SELDI-TOF mass spectrometry.

Surface-enhanced laser desorption ionization mass spectrometry (SELDI-TOFMS) was used to develop a new and useful method for determination and identification of the cyanobacterial (blue-green algae) toxins: microcystin and nodularin. The technique, combining chromatography and MS, enables microcystin/nodularin capture, purification, analysis, and processing from complex biological mixtures directly onto a hydrophobic chip. Factors affecting ion intensities, including matrix concentration and laser intensity, were investigated to optimize sensitivity of the method. Microcystins and nodularin were analyzed for femtomolar sensitivity (about 2.5 pg microcystin-LR in 2 microl water). Samples of blood sera and liver tissue were spiked with microcystin-LR and analyzed. The detection limit was 1 ng in 2 microl blood sera solution. Reactions of microcystins by compounds containing mercaptan groups, such as dithiothreitol, aminoethanethiol and protein phosphatase 1, were examined on the chip by mass spectrometry. Formation of the microcystin-dithiothreitol conjugate was used to confirm the target compounds. The MS/MS data obtained showed the presence of the microcystin conjugate. The reaction position of the toxin with target compound was confirmed by a series of MS/MS fragment ions. The protein profile of microcystins reacting with protein phosphatase 1 was also obtained from the SELDI-TOF mass spectra.

Cyanobacteria↗

PubMed2006

Bacterial degradation of microcystin toxins within a biologically active sand filter.

Microcystin toxins are a problem for water authorities as they are recalcitrant to conventional water treatment. In this study, biological sand filtration was assessed in laboratory column experiments for its ability to remove two microcystin analogues, microcystin-LR and microcystin-LA. A lag period of 3 days was evident prior to the commencement of degradation. Contact times were varied during the experiment; however, no microcystin was detected in the effluent after 4 days, even under conditions similar to those of a rapid sand filter. Removals of microcystin through the sand filters were shown to be primarily through biological degradation processes. Using polymerase chain reaction (PCR), biofilm, extracted from one of the sand filters that had effectively removed the microcystins, was shown to contain bacteria with the mlrA gene. Detection of this gene provided additional evidence that biological degradation of microcystin was the primary removal mechanism.

Bacterial Toxins↗

PubMed2006

Microcystin analysis in single filaments of Planktothrix spp. in laboratory cultures and environmental blooms.

Single filaments of Planktothrix spp. were isolated from laboratory cultures of P. agardhii (NIES 595) and P. rubescens (SL 03) and from four freshwater lakes in England and Turkey. Filament lengths were measured and microcystins were extracted by freeze-thawing and boiling. Microcystin analysis of the isolated single filaments was performed by ELISA using antibodies raised against microcystin-LR with a minimum detection limit (MDL) of 11 pg filament(-1). In some cases a high percentage of the filaments from the environmental samples and laboratory cultures were below the MDL of the assay. Based on the filaments with detectable microcystin contents, P. agardhii from Bassenthwaite Lake (England) had the lowest mean microcystin concentration (0.7 fg microm(-3)), and the highest microcystin concentration (2.9 fg microm(-3)) was measured in P. rubescens from Iznik Lake (Turkey). We investigated the relationship for filaments with microcystin contents above MDL and their biovolume. Relationships varied widely although P. agardhii from Bassenthwaite showed a better (positive) relationship between filament biovolume and microcystin content than P. rubescens from environmental samples. Under culture conditions, P. rubescens showed a good relationship between filament biovolume and toxin content.

Cyanobacteria↗

PubMed2001

Microcystin contamination in fish from the Jacarepaguá Lagoon (Rio de Janeiro, Brazil): ecological implication and human health risk.

Chronic and subchronic toxicity from exposure to microcystins, cyclic peptide liver toxins from certain cyanobacteria, poses an important hazard, which has received little study. No in vivo information exists on accumulation and transfer of microcystin from the food chain to humans. This paper present results of a 3-year study that demonstrates bioaccumulation of microcystins by fish and potential rates of microcystin ingestion by humans. The study was carried out in a shallow coastal lagoon in the city of Rio de Janeiro (Jacarepaguá Lagoon). Fish (Tilapia rendalli) were collected every 2 weeks from August 1996 to November 1999. Microcystins were analyzed by HPLC in phytoplankton, fish liver and viscera while fish muscle tissue was analyzed by enzyme linked immunosorbant assay (ELISA). Phytoplankton samples, dominated by the genus Microcystis, were confirmed to contain microcystins as were fish livers, viscera and muscle tissue. During the entire study period, including times of low water bloom densities, fish muscle tissue contained concentrations of microcystins close to or above the recommended limit for human consumption (0.04 microg x kg(-1) day). Our findings demonstrate that microcystins can accumulate in fish tissue used for human consumption. Rates of ingestion routinely exceed the TDI guidelines as set by the WHO for drinking water. Appropriate epidemiology and risk assessment should be undertaken so that an acceptable TDI and appropriate risk management decisions can be made for human consumption of fish which are harvested from cyanobacterial blooms that contain cyanotoxins.

Animals↗

PubMed2003

Microcystin-LR affects cytoskeleton and morphology of rabbit primary whole embryo cultured cells in vitro.

Microcystin-LR is the most frequently studied cyclic heptapeptide produced by different genera of cyanobacteria and is hepatotoxic to livestock and human populations. The adverse effects of microcystin-LR on morphology and cytoskeletal elements in different stages of early embryonal development have been studied in vitro. Embryos and whole embryo cultures have been exposed to microcystin-LR (10-100 microM). Actin filaments were visualized by fluorescence staining and the microtubular network labelled by immunostaining. Growth, development and cytoskeleton organization of the embryos embedded in zona pellucida are not affected by microcystin-LR in concentrations up to 100 microM, while whole embryo cell cultures are affected by the presence of microcystin-LR in the culture medium. High microcystin-LR concentrations (100 microM) cause cells to be detached and destroyed, while lower concentrations (10-20 microM) profoundly affect actin and microtubule organization. These effects are confirmed also by the presence of transformed microcystin-LR in all the media at the lowest concentrations. It seems that the changes to the cells are far more serious than that expressed in cell morphology. From our experiments we conclude that the presence of zona pellucida is an effective way of embryo protection against xenobiotics like microcystin-LR.

Actin Cytoskeleton↗

PubMed1998

The toxicology of microcystins.

Microcystins are a family of more than 50 structurally similar hepatotoxins produced by species of freshwater cyanobacteria, primarily Microcystis aeruginosa. They are monocyclic heptapeptides, characterised by some invariant amino acids, including one of unusual structure which is essential for expression of toxicity. Microcystins are chemically stable, but suffer biodegradation in reservoir waters. The most common member of the family, microcystin-LR (L and R identifying the 2 variable amino acids, in this case leucine and arginine respectively) has an LD50 in mice and rats of 36-122 microg/kg by various routes, including aerosol inhalation. Although human illnesses attributed to microcystins include gastroenteritis and allergic/irritation reactions, the primary target of the toxin is the liver, where disruption of the cytoskeleton, consequent on inhibition of protein phosphatases 1 and 2A, causes massive hepatic haemorrhage. Microcystins are tight-binding inhibitors of these protein phosphatases, with inhibition constants in the nanomolar range or lower. Uptake of microcystins into the liver occurs via a carrier-mediated transport system, and several inhibitors of uptake can antagonise the toxic effects of microcystins. The most effective of these is the antibiotic rifampin (a drug approved for clinical use), which protects mice and rats against microcystin-induced lethality when given prophylactically and, in some cases, therapeutically.

Animals↗

PubMed2003

Degradation of microcystin in sediments at oxic and anoxic, denitrifying conditions.

The potent toxin microcystin is frequently released during cyanobacterial blooms in eutrophic waters and may impose a risk to human health, when surface water is used for drinking water. For removal of microcystin in surface waters, infiltration through sediment is commonly used. In the present study, mineralization of 14C-labelled microcystin (accumulation of 14CO(2)) and concentration changes (protein phosphatase inhibition assay) demonstrated that indigenous microorganisms in the sediment of a water recharge facility were capable of degrading microcystin. At oxic or microaerophilic (<2% O(2)) conditions, microcystin added to sediment slurries at 70 microg l(-1) was reduced to <20 microg l(-1) in 1-2 weeks, and less than 3 microg l(-1) after 7 weeks. At anoxic conditions (<0.3% O(2)) and with addition of nitrate, the degradation was significantly stimulated, reducing microcystin from 100 to <20 microg l(-1) within 1 day. The simultaneous production of N(2)O in the samples suggests that the microcystin degradation was coupled to dissimilative nitrate reduction (denitrification). Since aquifers and sediments beneath drinking water reservoirs often are anoxic, nitrate respiration may be an important process in removal and detoxification of microcystin.

Biodegradation, Environmental↗

PubMed1997

Microcystin LR degradation by Pseudomonas aeruginosa alkaline protease.

We isolated several species of bacteria from the surface water of a Japanese lake. Of the isolated bacteria, Pseudomonas aeruginosa was the only species which could degrade microcystin LR in vitro. Microcystin LR decreased to 4.5% of the spiked microcystin LR quantity in the P. aeruginosa culture, and was metabolized to (2S, 3S, 8S)-3-amino-2, 6, 8-trimethyl-10-phenyldeca-4E, 6E-dienoic acid (DmADDA). It was possible that P. aeruginosa hydrolysed nucleophilically the peptide bond of microcystin LR. We examined if pyochelin, pyocyanin and alkaline protease produced by P. aeruginosa affected the reduction of microcystin LR. In the result, DmADDA was produced from microcystin LR in the presence of 100 microM H2O2 and 100 microM each of pyochelin, pyocyanin or both. However, the production of DmADDA was slight (2 to 12 mole%). After treatment with P. aeruginosa alkaline protease, DmADDA was produced 75 mole% from microcystin LR. Therefore, we concluded that microcystin was degraded mainly by the action of P. aeruginosa alkaline protease.

Amino Acids↗

PubMed1999

Effects of microcystins on phosphorylase-a binding to phosphatase-2A: kinetic analysis by surface plasmon resonance biosensor.

Cyclic heptapeptide microcystins are a group of hepatoxicants which exert the cytotoxic effects by inhibiting the catalytic activities of phosphatase-2A (PP-2A) and phosphatase-1 (PP-1) and thus disrupt the normal signal transduction pathways. Microcystins interact with PP-2A and PP-1 by a two-step mechanism involving rapid binding and inactivation of protein phosphatase catalytic subunit, followed by a slower covalent interaction. It was proposed that inactivation of PP-2A/PP-1 catalytic activity by microcystins precedes covalent adduct formation. In this study, we used a biosensor based on surface plasmon resonance (SPR) to examine the effects of three microcystins, MCLR, MCRR and MCYR, on the binding between PP-2A and its substrate, phosphorylase-a (PL-a), during the first step of the interaction. The SPR biosensor provides real-time information on the association and dissociation kinetics of PL-a with immobilized PP-2A in the absence and presence of microcystins. It was found that the affinity of PL-a to microcystin-bound PP-2A was four times smaller compared to unbound PP-2A, due to 50% decreases in the association rates and two-fold increases in dissociation rates of PL-a binding to PP-2A. The results suggest that the rapid binding of microcystins to the PP-2A catalytic site leads to the formation of a noncovalent microcystin/PP-2A adduct. While the adduct formation fully inhibits the catalytic activity of PP-2A, it only results in partial inhibition of the substrate binding. The similar effects of the three microcystins on PP-2A suggest that the toxins bind to PP-2A at the same site and cause similar conformational changes. The present work also demonstrates the potential application of biosensor technology in environmental toxicological research.

Binding Sites↗

PubMed2000

Co-occurrence of non-toxic (cyanopeptolin) and toxic (microcystin) peptides in a bloom of Microcystis sp. from a Chilean lake.

A cyanobacterial bloom occurring in 1998 in lake Tres Pascualas (Concepción/Chile) was found to be dominated by Microcystis sp. The bloom contained both non-toxic (cyanopeptolin-type) and hepatotoxic (microcystin-type) peptides. Cyanopeptolin structure of the non-toxic peptides (called cyanopeptolin VW-1 and VW-2, respectively) was revealed by matrix assisted laser desorption ionization mass spectrometry (MALDI-TOF-MS) of whole cells, showing dominant molecular ions at m/z = 975 and m/z 995, respectively. On post source decay (PSD), both cyanopeptolins showed fragments deriving from Ahp-Phe-MTyr (3-amino-6-hydroxy-2-piperidone), the characteristic partial structure of cyanopeptolins. The amounts of each of the two cyanopeptolins could only roughly be estimated to be >0.1% of bloom material dry weight. In addition the blooms contained microcystins (20 microg/g bloom dry weight as determined by RP-HPLC, 13 microg/g according to ELISA determination). MALDI-TOF-MS revealed several structural variants of microcystin: MCYST-RR (microcystin with Arg and Arg, indicated by m/z 1,038 and confirmed by PSD revealing a m/z = 135 fragment deriving from the Adda side chain, MCYST-FR (microcystin with Phe and Arg, indicated by m/z = 1,015). The presence of [Asp(3)]-MCYST-LR (microcystin with Leu and Arg, Asp non-methylated, indicated by m/z 981), and [Asp(3)]-MCYST-YR (microcystin with Tyr and Arg, Asp non-methylated, indicated by m/z 1,031) were likely. The relative amounts of the peptides varied between February, April, and May. Whole cell extracts from the bloom material revealed specific enzyme inhibitory activities. The serin-proteases trypsin, plasmin, elastase were inhibited, assumable due to the cyanopeptolins found. Elastase and the cysteine-protease papain were not inhibited, inhibitions of protein kinase and glutathione S-transferase (GST) were low. Strong inhibition was observed with protein-phosphatase-1, likely due to the microcystins present in the samples.

Bacterial Toxins↗

PubMed2000

Effects of physicochemical variables and cyanobacterial extracts on the immunoassay of microcystin-LR by two ELISA kits.

Two types of commercially available ELISA kits for the immunoassay of cyanobacterial microcystins were evaluated for potential interference effects due to methanol, salinity, pH, plasticware and cyanobacterial extract. Of the treatments examined, methanol had the greatest effect, giving false positive microcystin concentrations with increasing methanol concentrations up to 30% (v/v) compared with the negative calibrators of each kit. False positive microcystin results were also produced with increasing salinity up to full strength seawater. Decreases in microcystin-LR equivalents were observed when assaying purified microcystin-LR at pH values between 6.25 and 10. Aqueous microcystin-LR solutions in plastic microcentrifuge tubes after pipetting with disposable plastic tips had lower toxin concentrations than expected when analysed by ELISA. Indicated microcystin concentrations in cyanobacterial extracts varied between kit types and the choice of blanks used. Although ELISAs can be useful tools for the screening of water and cyanobacterial blooms for microcystins and nodularins, users should be aware that commercial kits can be susceptible to interference by commonly encountered environmental and laboratory conditions and materials.

Cyanobacteria↗

PubMed2005

Transformation of immortalized colorectal crypt cells by microcystin involving constitutive activation of Akt and MAPK cascade.

It has been shown by epidemiological and animal studies that microcystin is an important exogenous factor involved in the carcinogenesis of colorectal cancer (CRC). However, details of the mechanism remain unclear. Transformation of colorectal cells is an important initial step in carcinogenesis. Whether microcystin is capable of transforming immortalized colorectal crypt cells, and what the mechanism might be, was investigated. In the present study, we demonstrated that immortalized colorectal crypt cells could be transformed by microcystin. Transformed colorectal crypt cells showed an anchorage-independent growth phenotype, and the proliferation activities of microcystin-transformed cells were also greater than that of immortalized colorectal crypt cells. The Akt and the p38, JNK of mitogen-activated protein kinase (MAPK) pathways in microcystin-transformed cells were found to be constitutively activated. In microcystin-transformed cells, PI3K, MAPKAPK2, Akt, cyclin D1 and cyclin D3 in the Akt pathway; IQGAP-2, RabGTPase, Rap1GAP, RasGAP, R-Ras, Krev-1 and TC21 of the Ras GTP/GDP protein family; and A-Raf, B-Raf and PAK in the Ras/MAPK pathway were all markedly upregulated. However, in positive control cells, dimethylhydrazine-transformed cells, only the Akt pathway was activated by PI3K, and no evidence of alteration of any molecules of the Ras superfamily was observed. Inhibition of Akt, p38 and JNK activation led to a reduced proliferation of microcystin-transformed cells. This implies that the constitutive activation of Akt and the p38, JNK of MAPK pathways in microcystin-transformed cells may be the mechanism by which this important external factor acts in the carcinogenesis of CRC.

Cell Culture Techniques↗

PubMed2000

Polyketide synthase gene coupled to the peptide synthetase module involved in the biosynthesis of the cyclic heptapeptide microcystin.

The peptide synthetase gene operon, which consists of mcyA, mcyB, and mcyC, for the activation and incorporation of the five amino acid constituents of microcystin has been identified [T. Nishizawa et al. (1999) J. Biochem. 126, 520-529]. By sequencing an additional 34 kb of DNA from microcystin-producing Microcystis aeruginosa K-139, we identified the residual microcystin synthetase gene operon, which consists of mcyD, mcyE, mcyF, and mcyG, in the opposite orientation to the mcyABC operon. McyD consisted of two polyketide synthase modules, and McyE contained a polyketide synthase module at the N-terminus and a peptide synthetase module at the C-terminus. McyF was found to exhibit similarity to amino acid racemase. McyG consisted of a peptide synthetase module at the N-terminus and a polyketide synthase at the C-terminus. The microcystin synthetase gene cluster was conserved in another microcystin-producing strain, Microcystis sp. S-70, which produces Microcystin-LR, -RR, and -YR. Insertional mutagenesis of mcyA, mcyD, or mcyE in Microcystis sp. S-70 abolished microcystin production. In conclusion, the mcyDEFG operon is presumed to be responsible for 3-amino-9-methoxy-2,6, 8-trimethyl-10-phenyldeca-4,6-dienoic acid (Adda) biosynthesis, and the incorporation of Adda and glutamic acid into the microcystin molecule.

Amino Acid Sequence↗

PubMed1991

Structure-function relationships of microcystins, liver tumor promoters, in interaction with protein phosphatase.

Microcystins, isolated from toxic blue-green algae, are potent inhibitors of protein phosphatases 1 and 2A. Recently, we have reported that microcystin LR has a potent tumor-promoting activity on rat liver initiated with diethylnitrosamine. The structure of microcystins is unique in having an unusual amino acid, 3-amino-9-methoxy-10-phenyl-2,6,8-trimethyl-deca-4(E),6(E)-dienoic acid (Adda), which is thought to be significant for the activity. Geometrical isomers at C-7 in the Adda portion of microcystins, 6(Z)-Adda microcystins LR and RR, have been isolated from cyanobacteria. To estimate their tumor-promoting activities and to understand the importance of the Adda portion for activity, the maternal microcystins LR and RR and their isomers were subjected to examination of their interaction with protein phosphatases 1 and 2A and the release of glutamic pyruvic transaminase from rat liver. 6(Z)-Adda microcystins LR and RR bound to protein phosphatases 1 and 2A, inhibited their activities and released glutamic pyruvic transaminase from rat liver into serum, ten to one hundred times more weakly than the maternal microcystins LR and RR. These results indicated that the conjugated diene with 4(E),6(E) geometry in the Adda portion is important in the interaction with protein phosphatases.

Alanine Transaminase↗

PubMed2003

Quantitative real-time PCR for determination of microcystin synthetase e copy numbers for microcystis and anabaena in lakes.

Cyanobacterial mass occurrences in freshwater lakes are generally formed by Anabaena, Microcystis, and Planktothrix, which may produce cyclic heptapeptide hepatotoxins, microcystins. Thus far, identification of the most potent microcystin producer in a lake has not been possible due to a lack of quantitative methods. The aim of this study was to identify the microcystin-producing genera and to determine the copy numbers of microcystin synthetase gene E (mcyE) in Lake Tuusulanjärvi and Lake Hiidenvesi in Finland by quantitative real-time PCR. The microcystin concentrations and cyanobacterial cell densities of these lakes were also determined. The microcystin concentrations correlated positively with the sum of Microcystis and Anabaena mcyE copy numbers from both Lake Tuusulanjärvi and Lake Hiidenvesi, indicating that mcyE gene copy numbers can be used as surrogates for hepatotoxic Microcystis and ANABAENA: The main microcystin producer in Lake Tuusulanjärvi was Microcystis spp., since average Microcystis mcyE copy numbers were >30 times more abundant than those of ANABAENA: Lake Hiidenvesi seemed to contain both nontoxic and toxic Anabaena as well as toxic Microcystis strains. Identifying the most potent microcystin producer in a lake could be valuable for designing lake restoration strategies, among other uses.

Anabaena↗