Combined toxic effects of yessotoxin and polystyrene on the survival, reproduction, and population growth of rotifer Brachionus plicatilis at different temperatures.

Yessotoxin (YTX) is a disulfated toxin produced by harmful dinoflagellates and causes risks to aquatic animals. Polystyrene (PS) microplastics could absorb toxins in seawaters but pose threats to organism growth. In this study, the combined toxic effects of YTX (0, 20, 50, and 100 µg L-1) and PS (0, 5, and 10 µg mL-1) on the survival, reproduction, and population growth of marine rotifer Brachionus plicatilis at 20 °C, 25 °C, and 30 °C were evaluated. Results indicated that the survival time (S), time to first batch of eggs (Ft), total offspring per rotifer (Ot), generational time (T0), net reproduction rate (R0), intrinsic growth rate (rm), and population growth rate (r) of rotifers were inhibited by YTX and PS at 25 °C and 30 °C. Low temperature (20 °C) improved the life-table parameters T0, R0, and rm at YTX concentrations less than 100 µg L-1. Temperature, YTX, and PS had interactive effects on rotifers' S, Ft, Ot, T0, R0, rm, and r. The combined negative effects of YTX and PS on rotifers' survival, reproduction, and population growth were significantly enhanced at 30 °C. These findings emphasized the importance of environmental temperature in studying the interactive effects of microplastics and toxins on the population growth of zooplankton in eutrophic seawaters.

Chemistry and bioactivity of marine algal toxins and their geographic distribution in China.

Marine algal toxins are usually produced by some toxic algae during toxic algal blooms which can be accumulated in marine organisms through food chains, leading to contamination of aquatic products. Consumption of the contaminated seafood often results in poisoning in human being. Although algal toxins are harmful for human health, their unique structures and broad spectrum of biological activities have attracted widespread attention of chemists and pharmacologists. Marine algal toxins are not only a reservoir of biological active compound discovery, but also powerful tools for exploring life science. This review first provides a comprehensive overview of the chemistry and biological activities of marine algal toxins, with the aim of providing references for biological active compound discovery. Additionally, typical shellfish poisoning incidents occurred in China in the past 15 years and the geographical distribution of the marine algal toxins in China Sea are discussed, for the purpose of enhancing public awareness of the possible dangers of algal toxins.

Understanding the risks of co-exposures in a changing world: a case study of dual monitoring of the biotoxin domoic acid and Vibrio spp. in Pacific oyster.

Assessing the co-occurrence of multiple health risk factors in coastal ecosystems is challenging due to the complexity of multi-factor interactions and limited availability of simultaneously collected data. Understanding co-occurrence is particularly important for risk factors that may be associated with, or occur in similar environmental conditions. In marine ecosystems, the co-occurrence of harmful algal bloom toxins and bacterial pathogens within the genus Vibrio may impact both ecosystem and human health. This study examined the co-occurrence of Vibrio spp. and domoic acid (DA) produced by the harmful algae Pseudo-nitzschia by (1) analyzing existing California Department of Public Health monitoring data for V. parahaemolyticus and DA in oysters; and (2) conducting a 1-year seasonal monitoring of these risk factors across two Southern California embayments. Existing public health monitoring efforts in the state were robust for individual risk factors; however, it was difficult to evaluate the co-occurrence of these risk factors in oysters due to low number of co-monitoring instances between 2015 and 2020. Seasonal co-monitoring of DA and Vibrio spp. (V. vulnificus or V. parahaemolyticus) at two embayments revealed the co-occurrence of these health risk factors in 35% of sampled oysters in most seasons. Interestingly, both the overall detection frequency and co-occurrence of these risk factors were considerably less frequent in water samples. These findings may in part suggest the slow depuration of Vibrio spp. and DA in oysters as residual levels may be retained. This study expanded our understanding of the simultaneous presence of DA and Vibrio spp. in bivalves and demonstrates the feasibility of co-monitoring different risk factors from the same sample. Individual programs monitoring for different risk factors from the same sample matrix may consider combining efforts to reduce cost, streamline the process, and better understand the prevalence of co-occurring health risk factors.

3D Monolayer Silanation of Porous Structure Facilitating Multi-Phase Pollutants Removal.

Activated carbon (AC) is widely used to removing hazardous pollutants from air and water, owing to its exceptional adsorption properties. However, the high affinity of water molecules with the surface oxygen-containing functional groups can adversely affect the adsorption performance of AC. In this study, a facile and efficient method is presented for fabrication of hydrophobic AC through surface monolayer silanation. Compared to initial AC, the hydrophobic AC improves the water contact angle from 29.7° to 123.5° while maintaining high specific surface area and enhances the removal capacity of multi-phase pollutants (emulsified oil and toluene). Additionally, the hydrophobic AC exhibits excellent adsorption capability to harmful algal bloom species (Chlorella) (97.56%) and algal organic matter (AOM) (96.23%) owing to electrostatic interactions and surface hydrophobicity. The study demonstrates that this method of surface monolayer silanation can effectively weaken the effect of water molecules on AC adsorption capacity, which has significant potential for practical use in air and water purification, as well as in the control of harmful algal blooms.

Ultrasensitive Aptasensor for Microcystin-LR Detection in Food Samples Based on Target-Activated Assembly of Y-Shaped Hairpin Probes.

As a kind of algal toxin, microcystin-LR (MC-LR) causes a tremendous treat to food safety and the detection of trace levels of MC-LR is highly desirable. Herein, we developed an ultrasensitive aptasensor for MC-LR detection based on target-activated assembly of Y-shaped hairpins. The aptamer-target recognition initiates the assembly step between two Y-shaped hairpin probes through toehold-mediated DNA replacement. One of the hairpins was modified with FAM and BHQ. Through cyclic assembly reactions, a high fluorescence signal can be observed in the product. The detection limit is 0.2 pM for MC-LR detection. In addition, the biosensor is robust and has been successfully explored to assess the MC-LR concentrations in real fish and water samples with satisfactory recovery rates and good accuracy. The signal amplification can be gained through the cyclic Y-shaped hairpin assembly, which offers a simple, ultrasensitive, and reliable method for MC-LR monitoring in food samples.

Are little brown bats (Myotis lucifugus) impacted by dietary exposure to microcystin?✰.

The cyanobacterium, Microcystis aeruginosa, can produce the hepatotoxin microcystin. When toxic M. aeruginosa overwinters in the sediments of lakes, it may be ingested by aquatic insects and bioaccumulate in nymphs of Hexagenia mayflies. When volant Hexagenia emerge from lakes to reproduce, they provide an abundant, albeit temporary, food source for many terrestrial organisms including bats. Little brown bats, Myotis lucifugus, feed opportunistically on aquatic insects including Hexagenia. To determine if microcystin moves from aquatic to terrestrial ecosystems via trophic transfer, we combined a dietary analysis with the quantification of microcystin in bat livers and feces. In June 2014, coincident with the local Hexagenia emergence, bat feces were collected from underneath a maternity roost near Little Traverse Lake (Leelanau County, Michigan, USA). Insects in the diet were identified via molecular analyses of fecal pellets from the roost and from individual bats. Livers and feces were collected from 19 female M. lucifugus, and the concentrations of microcystin in these liver tissues and feces were measured using an enzyme-linked immunosorbent assay (ELISA) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). We show that the majority of the bats' diets consisted of aquatic insects and that microcystin was detected in high concentrations (up to 129.9 µg/kg dw) in the bat feces by ELISA. Histopathological examination of three bat livers with the highest concentrations of microcystin showed no evidence of phycotoxicosis, indicating that M. lucifugus may not be immediately affected by the ingestion of microcystin. Future work could examine whether bats suffer delayed physiological effects from ingestion of microcystin.

Non-target analysis and stability assessment of reference materials using liquid chromatography‒high-resolution mass spectrometry.

Development and characterization of biological and environmental matrix certified reference materials (CRMs) for organic analytes typically relies heavily on targeted analytical methods, such as liquid chromatography (LC) with triple-quadrupole mass spectrometry detection. LC with high-resolution mass spectrometry (LC‒HRMS) can also provide high quality data for both targeted and non-targeted analytes, with the potential for retrospective data analysis. Here, we demonstrate the utility of non-target analysis (NTA) using LC‒HRMS for profiling and stability assessment of a mussel tissue matrix CRM certified for several classes of marine algal toxins (CRM-FDMT1). First, the NTA method was developed using data-dependent MS/MS acquisition and commercial metabolomics software for data processing. Of 128 toxin analogues previously reported in CRM-FDMT1, 125 were detected by LC-HRMS, with 97 triggered for MS/MS by data dependant acquisition. Automated data processing detected 119 of these compounds and 109 were retained after automated filtering of results for putative toxin analogues. Those analogues not detected were low abundance ions, or poorly resolved isomers. The method was then used to demonstrate new strategies for CRM stability assessment considering the stability of certified analytes, related toxin analogues, and unrelated matrix compounds. Several analogues from each toxin class in CRM-FDMT1 as well as other unrelated matrix compounds were observed to be significantly less stable than the certified toxins. Using this method, no instability was measured for any compounds at conditions ≤4 °C, providing a greater degree of confidence in CRM stability than could be achieved using conventional approaches to stability assessment targeting only the certified analytes. The NTA method and stability assessment approach presented are applicable to future CRM development with other matrices and organic analyte classes.

Aptamers functionalized hybrid nanomaterials for algal toxins detection and decontamination in aquatic system: Current progress, opportunities, and challenges.

Purification and detection of algal toxins is the most effective technique to ensure that people have clean and safe drinking water. To achieve these objectives, various state-of-the-art technologies were designed and fabricated to decontaminate and detect algal toxins in aquatic environments. Amongst these technologies, aptamer-functionalized hybrid nanomaterials conjugates have received significant consideration as a result of their several benefits over other methods, such as good controllable selectivity, low immunogenicity, and biocompatibility. Because of their excellent properties, aptamer-functionalized hybrid nanomaterials conjugates are one of several remarkable agents. Several isolated aptamer sequences for algal toxins are addressed in this review, as well as aptasensor and decontamination aptamer functionalized metal nanoparticle-derived hybrid nanocomposites applications. In addition, we present diverse aptamer-functionalized hybrid nanomaterial conjugates designs and their applications for sensing and decontamination.

An eco-environmental assessment of harmful algal bloom mitigation using modified clay.

The application of modified clay (MC) to mitigate harmful algal blooms (HABs) is becoming a widespread practice in China because of its low cost, high efficiency and environmental friendliness. Due to its success in China, this technology has also gained international recognition in recent years. Nevertheless, the eco-environmental impacts of this technology still remain to be a concern to many customers and government agencies, which has motivated scientists in both China and many other countries to evaluate its potential effects on nontarget aquatic organisms, water quality and the benthic environment. This paper reviews the results from these studies both in the laboratory and in the field, which showed that MC does not harm nontarget aquatic organisms and has no negative impact on water quality or the benthic environment. Additionally, findings show that MC can alter nutrient cycling and reduce algal toxins in water bodies. Furthermore, researchers also found that MC affects cyst formation and germination in sedimentary environments. This review is expected to provide scientific guidance for mitigating HABs in China and worldwide using clay or MC.

Asynchrony of Gambierdiscus spp. Abundance and Toxicity in the U.S. Virgin Islands: Implications for Monitoring and Management of Ciguatera.

Ciguatera poisoning (CP) poses a significant threat to ecosystem services and fishery resources in coastal communities. The CP-causative ciguatoxins (CTXs) are produced by benthic dinoflagellates including Gambierdiscus and Fukuyoa spp., and enter reef food webs via grazing on macroalgal substrates. In this study, we report on a 3-year monthly time series in St. Thomas, US Virgin Islands where Gambierdiscus spp. abundance and Caribbean-CTX toxicity in benthic samples were compared to key environmental factors, including temperature, salinity, nutrients, benthic cover, and physical data. We found that peak Gambierdiscus abundance occurred in summer while CTX-specific toxicity peaked in cooler months (February-May) when the mean water temperatures were approximately 26-28 °C. These trends were most evident at deeper offshore sites where macroalgal cover was highest year-round. Other environmental parameters were not correlated with the CTX variability observed over time. The asynchrony between Gambierdiscus spp. abundance and toxicity reflects potential differences in toxin cell quotas among Gambierdiscus species with concomitant variability in their abundances throughout the year. These results have significant implications for monitoring and management of benthic harmful algal blooms and highlights potential seasonal and highly-localized pulses in reef toxin loads that may be transferred to higher trophic levels.

Harmful algal blooms and their eco-environmental indication.

Harmful algal blooms (HABs) in freshwater lakes and oceans date back to as early as the 19th century, which can cause the death of aquatic and terrestrial organisms. However, it was not until the end of the 20th century that researchers had started to pay attention to the hazards and causes of HABs. In this study, we analyzed 5720 published literatures on HABs studies in the past 30 years. Our review presents the emerging trends in the past 30 years on HABs studies, the environmental and human health risks, prevention and control strategies and future developments. Therefore, this review provides a global perspective of HABs and calls for immediate responses.

Brevetoxin and Conotoxin Interactions with Single-Domain Voltage-Gated Sodium Channels from a Diatom and Coccolithophore.

The recently characterized single-domain voltage-gated ion channels from eukaryotic protists (EukCats) provide an array of novel channel proteins upon which to test the pharmacology of both clinically and environmentally relevant marine toxins. Here, we examined the effects of the hydrophilic µ-CTx PIIIA and the lipophilic brevetoxins PbTx-2 and PbTx-3 on heterologously expressed EukCat ion channels from a marine diatom and coccolithophore. Surprisingly, none of the toxins inhibited the peak currents evoked by the two EukCats tested. The lack of homology in the outer pore elements of the channel may disrupt the binding of µ-CTx PIIIA, while major structural differences between mammalian sodium channels and the C-terminal domains of the EukCats may diminish interactions with the brevetoxins. However, all three toxins produced significant negative shifts in the voltage dependence of activation and steady state inactivation, suggesting alternative and state-dependent binding conformations that potentially lead to changes in the excitability of the phytoplankton themselves.

Potential causative factors of noble scallop Chlamys nobilis mass mortality in Nan'ao Island, Shantou, China in 2017.

Noble scallop Chlamys nobilis is an important marine bivalve that has been extensively cultured in the south coast of China since the 1980s. Unfortunately, since the late 1990s, the farmed scallops often suffered from regional mass mortality, which results in enormous economic losses to farmers and industries. In 2017, another mass mortality event occurred in Nan'ao Island, Shantou, China. In this study, the cause of C. nobilis mass mortality in 2017 was first investigated in the field, and then validated in a laboratory experiment. In the field, three sampling sites were selected according to the scallop mortality rate: Hunter Bay (90% mortality), Baisha Bay (67% mortality) and Longhai (6% mortality). Meanwhile, environmental parameters (temperature, salinity, DO, pH and chlorophyll a) of each site were also measured in situ. Then, water and scallop samples were collected randomly for the analysis of phytoplankton diversity and algal toxin activity using 18S rDNA and PP2A inhibition assay, respectively. In laboratory, healthy scallops were challenged with Karenia mikimotoi (1 × 103 cells/mL) for 30 h. The field results showed that no significant difference in those environmental parameters existed among the three sites, but the relative abundance of K. mikimotoi in seawater and scallops' intestines in Hunter Bay and Baisha Bay was significantly higher than that in Longhai, and sick scallops contained significantly higher algal toxin activity than healthy ones. Laboratory results revealed that challenged scallops with K. mikimotoi showed significantly higher mortality rate and algal toxin activity than healthy ones, and low density of K. mikimotoi (1 × 103 cells/mL) was sufficient to cause >50% scallops' mortality within 26 h. This study provides the first evidence that low K. mikimotoi cell density can cause massive mortality in C. nobilis, and provides useful information as guide to prevent scallop mass mortality in the future.

The effect of temperature on physiology, toxicity and toxin content of the benthic dinoflagellate Coolia malayensis from a seasonal tropical region.

Coolia malayensis is one of the commonly found benthic dinoflagellates in Hong Kong which can produce biotoxins and threaten the early life stages of marine invertebrates. Seawater temperature has been recognized as one of the primary environmental factors that affect the formation of harmful algal blooms. The present study evaluated the responses of C. malayensis, including growth, toxicity and toxin content (putative analogues of okadaic acid and azaspiracids), after exposure to a range of seven different temperatures (i.e., 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, and 28°C). The highest algal density and specific growth rate were recorded at 24°C. Significantly higher Fv/Fm (maximum quantum yield of PSII) and total phaeo-pigment values were observed in the exponential growth phase at 28°C. The toxicity of the algal extract, which was assessed by the lethality rate of Artemia larvae, increased with temperature. The highest toxin content was detected at the second highest temperature treatment, i.e., 26°C. Overall, temperature had significant effects on the physiological activities and toxicity of C. malayensis. This study has raised attention to the potentially increasing risks posed by toxic benthic dinoflagellates during heat waves in coastal waters.

Hemolysis associated toxicities of benthic dinoflagellates from Hong Kong waters.

Benthic dinoflagellates produce a diverse range of phycotoxins, which are responsible for intoxication events in marine fauna. This study assessed the hemolysis associated toxicities of six species of benthic dinoflagellates from the genera Coolia, Fukuyoa, Amphidinium and Prorocentrum. Results demonstrated that Amphidinium carterae, Coolia tropicalis and Fukuyoa ruetzleri were the three most toxic species, while Prorocentrum cf. lima did not have significant hemolytic effect. Grouper samples (Cephalopholis boenak) were more tolerant to the hemolytic algae than the blackhead seabream (Acanthopagrus schlegelii), with decreased heart rate and blood flow being observed in medaka larvae after exposure to toxic algal extracts. LC-MS/MS analysis detected a gambierone analogue called 44-methylgambierone produced by the C. tropicalis isolate. This analogue was also detected in the F. ruetzleri isolate. This study provided new information on the hemolysis associated toxicities of local toxic benthic dinoflagellates, which contributes to better understanding of their emerging threats to marine fauna and reef systems in Hong Kong.

Discovery of a Potential Human Serum Biomarker for Chronic Seafood Toxin Exposure Using an SPR Biosensor.

Domoic acid (DA)-producing harmful algal blooms (HABs) have been present at unprecedented geographic extent and duration in recent years causing an increase in contamination of seafood by this common environmental neurotoxin. The toxin is responsible for the neurotoxic illness, amnesic shellfish poisoning (ASP), that is characterized by gastro-intestinal distress, seizures, memory loss, and death. Established seafood safety regulatory limits of 20 µg DA/g shellfish have been relatively successful at protecting human seafood consumers from short-term high-level exposures and episodes of acute ASP. Significant concerns, however, remain regarding the potential impact of repetitive low-level or chronic DA exposure for which there are no protections. Here, we report the novel discovery of a DA-specific antibody in the serum of chronically-exposed tribal shellfish harvesters from a region where DA is commonly detected at low levels in razor clams year-round. The toxin was also detected in tribal shellfish consumers' urine samples confirming systemic DA exposure via consumption of legally-harvested razor clams. The presence of a DA-specific antibody in the serum of human shellfish consumers confirms long-term chronic DA exposure and may be useful as a diagnostic biomarker in a clinical setting. Adverse effects of chronic low-level DA exposure have been previously documented in laboratory animal studies and tribal razor clam consumers, underscoring the potential clinical impact of such a diagnostic biomarker for protecting human health. The discovery of this type of antibody response to chronic DA exposure has broader implications for other environmental neurotoxins of concern.

Uptake and localization of fluorescently-labeled Karenia brevis metabolites in non-toxic marine microbial taxa.

Brevetoxin (PbTx) is a neurotoxic secondary metabolite of the dinoflagellate Karenia brevis. We used a novel, fluorescent BODIPY-labeled conjugate of brevetoxin congener PbTx-2 (B-PbTx) to track absorption of the metabolite into a variety of marine microbes. The labeled toxin was taken up and brightly fluoresced in lipid-rich regions of several marine microbes including diatoms and coccolithophores. The microzooplankton (20-200 µm) tintinnid ciliate Favella sp. and the rotifer Brachionus rotundiformis also took up B-PbTx. Uptake and intracellular fluorescence of B-PbTx was weak or undetectable in phytoplankton species representative of dinoflagellates, cryptophytes, and cyanobacteria over the same (4 h) time course. The cellular fate of two additional BODIPY-conjugated K. brevis associated secondary metabolites, brevenal (B-Bn) and brevisin (B-Bs), were examined in all the species tested. All taxa exhibited minimal or undetectable fluorescence when exposed to the former conjugate, while most brightly fluoresced when treated with the latter. This is the first study to observe the uptake of fluorescently-tagged brevetoxin conjugates in non-toxic phytoplankton and zooplankton taxa, demonstrating their potential in investigating whether marine microbes can serve as a significant biological sink for algal toxins. The highly variable uptake of B-PbTx observed among taxa suggests some may play a more significant role than others in vectoring lipophilic toxins in the marine environment.

Effectors of thioredoxin reductase: Brevetoxins and manumycin-A.

The activities of two effectors, brevetoxin (PbTx) and manumycin-A (Man-A), of thioredoxin reductase (TrxR) have been evaluated against a series of fourteen TrxR orthologs originating from mammals, insects and protists and several mutants. Man-A, a molecule with numerous electrophilic sites, forms a covalent adduct with most selenocystine (Sec)-containing TrxR enzymes. The evidence also demonstrates that Man-A can form covalent adducts with some non-Sec-containing enzymes. The activities of TrxR enzymes towards various substrates are moderated by Man-A either positively or negatively depending on the enzyme. In general, the reduction of substrates by Sec-containing TrxR is inhibited and NADPH oxidase activity is activated. For non-Sec-containing TrxR the effect of Man-A on the reduction of substrates is variable, but NADPH oxidase activity can be activated even in the absence of covalent modification of TrxR. The effect of PbTx is less pronounced. A smaller subset of enzymes is affected by PbTx. With a single exception, the activities of most of this subset are activated. Although both PbTx variants can react with selenocysteine, a stable covalent adduct is not formed with any of the TrxR enzymes. The key findings from this work are (i) the identification of an alternate mechanism of toxicity for the algal toxin brevetoxin (ii) the demonstration that covalent modification of TrxR is not a prerequisite for the activation of NADPH oxidase activity of TrxR and (iii) the identification of an inhibitor which can discriminate between cytosolic and mitochondrial TrxR.

Electrochemical Biosensing of Algal Toxins in Water: The Current State-of-the-Art.

Due to increasing stringency of water legislation and extreme consequences that failure to detect some contaminants in water can involve, there has been a strong interest in developing electrochemical biosensors for algal toxin detection during the past decade, evidenced by literature increasing from 2 journal papers pre-2009 to 24 between 2009 and 2018. In this context, this review has summarized recent progress of successful algal toxin detection in water using electrochemical biosensing techniques. Satisfactory detection recoveries using real environmental water samples and good sensor repeatability and reproducibility have been achieved, along with some excellent limit-of-detection (LOD) reported. Recent electrochemical biosensor literature in algal toxin detection is compared and discussed to cover three major design components: (1) biorecognition elements, (2) electrochemical read-out techniques, and (3) sensor electrodes and signal amplification strategy. The recent development of electrochemical biosensors has provided one more step further toward quick in situ detection of algal toxins in the contamination point of the water source. In the end, we have also critically reviewed the current challenges and research opportunities regarding electrochemical biosensors for algal toxin detection that need to be addressed before they attain commercial viability.

Transformation of microcystin-LR and olefinic compounds by ferrate(VI): Oxidative cleavage of olefinic double bonds as the primary reaction pathway.

The presence of toxic microcystins in algal-impacted surface waters is a concern for drinking water quality management. In this study, the potential of ferrate(VI) to eliminate microcystins during drinking water treatment was assessed by investigating reaction kinetics, reaction sites, transformation products, and toxicity changes for the oxidation of microcystin-LR (MC-LR) as a representative microsystin. The investigations also included several substructural model compounds of MC-LR, such as cinnamic acid and sorbic acid, to elucidate the major transformation products and pathways of MC-LR and olefinic compounds. Second-order rate constants were determined in the pH range 6-10.4 for the reaction of ferrate(VI) with MC-LR and the model compounds. The kinetic data revealed that the olefinic double bonds in the Adda and Mdha residues of MC-LR were the primary ferrate(VI) reaction sites, while the phenyl or guanidine moiety was not the reaction site. This finding was supported by detection and identification of the MC-LR transformation products of double bond cleavage, with high peak abundance in the liquid chromatography-mass spectrometry. Furthermore, the reaction of ferrate(VI) with cinnamic and sorbic acids formed the corresponding aldehydes and organic acids with near complete carbon mass balance, indicating the oxidative cleavage of the double bonds as the primary reaction pathway. A quantitative protein phosphatase 2A (PP2A) binding assay for ferrate(VI)-treated MC-LR solutions showed that the MC-LR transformation products exhibited negligible PP2A binding activity compared to that of the parent MC-LR. Oxidation experiments in a filtered river water matrix spiked with MC-LR demonstrated the efficient elimination of MC-LR during water treatment with ferrate(VI).