Search Results (53)

In this paper, we examine the filamentous cyanobacterial strain NILCB16 and describe it as a new species within the genus Pegethrix. The original population was sampled from a mat growing in an irrigation canal in the Nile River, Egypt. Initially classified under Plectonema or Planktolyngbya, the strain is a potential producer of the toxins microcystin and β-N-Methylamino-L-Alanine (BMAA). Additionally, we reviewed the taxonomic relationships between the Oculatellales genera. To describe the new species, we conducted a polyphasic study, encompassing 16S rRNA gene phylogenetic analyses performed using both Maximum Likelihood and Bayesian methods, sequence identity (p-distance) analysis, 16S-23S ITS secondary structures, and morphological and habitat comparisons. The phylogenetic analysis revealed that strain NILCB16 clustered within the Pegethrix clade with strong phylogenetic support, but in a distinct position from other species in the genus. The strain shared a maximum 16S rRNA gene identity of 97.3% with P. qiandaoensis and 96.1% with the type species, P. bostrychoides. Morphologically, NILCB16 can be differentiated from other species in the genus by its lack of false branching. Our phylogenetic analyses also show that Pegethrix, Cartusia, Elainella, and Maricoleus are clustered with strong phylogenetic support. They exhibit high 16S rRNA gene identity and are morphologically indistinguishable, suggesting they could potentially be merged into a single genus in the future. Full article

The floating freshwater fern Azolla is the only plant that retains an endocyanobiont, Nostoc azollae (aka Anabaena azollae), during its sexual and asexual reproduction. The increased interest in Azolla as a potential source of food and its unique evolutionary history have raised questions about its cyanotoxin content and genome. Cyanotoxins are potent toxins synthesized by cyanobacteria which have an anti-herbivore effect but have also been linked to neurodegenerative disorders including Alzheimer’s and Parkinson’s diseases, liver and kidney failure, muscle paralysis, and other severe health issues. In this study, we investigated 48 accessions of Azolla–Nostoc symbiosis for the presence of genes coding microcystin, nodularin, cylindrospermopsin and saxitoxin, and BLAST analysis for anatoxin-a. We also investigated the presence of the neurotoxin β-N-methylamino-L-alanine (BMAA) in Azolla and N. azollae through LC-MS/MS. The PCR amplification of saxitoxin, cylindrospermospin, microcystin, and nodularin genes showed that Azolla and its cyanobiont N. azollae do not have the genes to synthesize these cyanotoxins. Additionally, the matching of the anatoxin-a gene to the sequenced N. azollae genome does not indicate the presence of the anatoxin-a gene. The LC-MS/MS analysis showed that BMAA and its isomers AEG and DAB are absent from Azolla and Nostoc azollae. Azolla therefore has the potential to safely feed millions of people due to its rapid growth while free-floating on shallow fresh water without the need for nitrogen fertilizers. Full article

Lake Winnipeg in Manitoba, Canada is heavily impacted by harmful algal blooms that contain non-protein amino acids (NPAAs) produced by cyanobacteria: N-(2-aminoethyl)glycine (AEG), β-aminomethyl-L-alanine (BAMA), β-N-methylamino-L-alanine (BMAA), and 2,4-diaminobutyric acid (DAB). Our objective was to investigate the impact of microbial diversity on NPAA production by cyanobacteria using semi-purified crude cyanobacterial cultures established from field samples collected by the Lake Winnipeg Research Consortium between 2016 and 2021. NPAAs were detected and quantified by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) using validated analytical methods, while Shannon and Simpson alpha diversity scores were determined from 16S rRNA metagenomic sequences. Alpha diversity in isolate cultures was significantly decreased compared to crude cyanobacterial cultures (p < 0.001), indicating successful semi-purification. BMAA and AEG concentrations were higher in crude compared to isolate cultures (p < 0.0001), and AEG concentrations were correlated to the alpha diversity in cultures (r = 0.554; p < 0.0001). BAMA concentrations were increased in isolate cultures (p < 0.05), while DAB concentrations were similar in crude and isolate cultures. These results demonstrate that microbial community complexity impacts NPAA production by cyanobacteria and related organisms. Full article

Cetaceans are well-regarded as sentinels for toxin exposure. Emerging studies suggest that cetaceans can also develop neuropathological changes associated with neurodegenerative disease. The occurrence of neuropathology makes cetaceans an ideal species for examining the impact of marine toxins on the brain across the lifespan. Here, we describe TAR DNA-binding protein 43 (TDP-43) proteinopathy and Alzheimer’s disease (AD) neuropathological changes in a beached harbor porpoise (Phocoena phocoena) that was exposed to a toxin produced by cyanobacteria called β-N-methylamino-L-alanine (BMAA). We found pathogenic TDP-43 cytoplasmic inclusions in neurons throughout the cerebral cortex, midbrain and brainstem. P62/sequestosome-1, responsible for the autophagy of misfolded proteins, was observed in the amygdala, hippocampus and frontal cortex. Genes implicated in AD and TDP-43 neuropathology such as APP and TARDBP were expressed in the brain. AD neuropathological changes such as amyloid-β plaques, neurofibrillary tangles, granulovacuolar degeneration and Hirano bodies were present in the hippocampus. These findings further support the development of progressive neurodegenerative disease in cetaceans and a potential causative link to cyanobacterial toxins. Climate change, nutrient pollution and industrial waste are increasing the frequency of harmful cyanobacterial blooms. Cyanotoxins like BMAA that are associated with neurodegenerative disease pose an increasing public health risk. Full article

Of the wide variety of toxic compounds produced by cyanobacteria, the neurotoxic amino acid β-N-methylamino-l-alanine (BMAA) has attracted attention as a result of its association with chronic human neurodegenerative diseases such as ALS and Alzheimer’s. Consequently, specific detection methods are required to assess the presence of BMAA and its isomers in environmental and clinical materials, including cyanobacteria and mollusks. Although the separation of isomers such as β-amino-N-methylalanine (BAMA), N-(2-aminoethyl)glycine (AEG) and 2,4-diaminobutyric acid (DAB) from BMAA has been demonstrated during routine analysis, a further compounding factor is the potential presence of enantiomers for some of these isomers. Current analytical methods for BMAA mostly do not discriminate between enantiomers, and the chiral configuration of BMAA in cyanobacteria is still largely unexplored. To understand the potential for the occurrence of D-BMAA in cyanobacteria, a chiral UPLC-MS/MS method was developed to separate BMAA enantiomers and isomers and to determine the enantiomeric configuration of endogenous free BMAA in a marine Lyngbya mat and two mussel reference materials. After extraction, purification and derivatization with N-(4-nitrophenoxycarbonyl)-l-phenylalanine 2-methoxyethyl ester ((S)-NIFE), both L- and D-BMAA were identified as free amino acids in cyanobacterial materials, whereas only L-BMAA was identified in mussel tissues. The finding of D-BMAA in biological environmental materials raises questions concerning the source and role of BMAA enantiomers in neurological disease. Full article

β-N-methylamino-L-alanine (BMAA) and its isomers, 2,4-diaminobutyric acid (2,4-DAB) and N-(2-aminoethyl)-glycine (AEG), along with microcystins (MCs)-RR, -LR, and -YR (the major MC congeners), are cyanotoxins that can cause detrimental health and environmental impacts during toxic blooms. Currently, there are no reverse-phase (RP) LC-MS/MS methods for the simultaneous detection and quantification of BMAA, its isomers, and the major MCs in a single analysis; therefore, multiple analyses are required to assess the toxic load of a sample. Here, we present a newly developed and validated method for the detection and quantification of BMAA, 2,4-DAB, AEG, MC-LR, MC-RR, and MC-YR using RP LC-MS/MS. Method validation was performed, assessing linearity (r² > 0.996), accuracy (>90% recovery for spiked samples), precision (7% relative standard deviation), and limits of detection (LODs) and quantification (LOQs) (ranging from 0.13 to 1.38 ng mL⁻¹). The application of this combined cyanotoxin analysis on a culture of Microcystis aeruginosa resulted in the simultaneous detection of 2,4-DAB (0.249 ng mg⁻¹ dry weight (DW)) and MC-YR (4828 ng mg⁻¹ DW). This study provides a unified method for the quantitative analysis of BMAA, its isomers, and three MC congeners in natural environmental samples. Full article

Shellfish accumulate microalgal toxins, which can make them unsafe for human consumption. In France, in accordance with EU regulations, three groups of marine toxins are currently under official monitoring: lipophilic toxins, saxitoxins, and domoic acid. Other unregulated toxin groups are also present in European shellfish, including emerging lipophilic and hydrophilic marine toxins (e.g., pinnatoxins, brevetoxins) and the neurotoxin β-N-methylamino-L-alanine (BMAA). To acquire data on emerging toxins in France, the monitoring program EMERGTOX was set up along the French coasts in 2018. Three new broad-spectrum LC-MS/MS methods were developed to quantify regulated and unregulated lipophilic and hydrophilic toxins and the BMAA group in shellfish (bivalve mollusks and gastropods). A single-laboratory validation of each of these methods was performed. Additionally, these specific, reliable, and sensitive operating procedures allowed the detection of groups of EU unregulated toxins in shellfish samples from French coasts: spirolides (SPX-13-DesMeC, SPX-DesMeD), pinnatoxins (PnTX-G, PnTX-A), gymnodimines (GYM-A), brevetoxins (BTX-2, BTX-3), microcystins (dmMC-RR, MC-RR), anatoxin, cylindrospermopsin and BMAA/DAB. Here, we present essentially the results of the unregulated toxins obtained from the French EMERGTOX monitoring plan during the past five years (2018–2022). Based on our findings, we outline future needs for monitoring to protect consumers from emerging unregulated toxins. Full article

This review is focused on the mechanisms that regulate health, disease and aging redox status, the signal pathways that counteract oxidative and reductive stress, the role of food components and additives with antioxidant properties (curcumin, polyphenols, vitamins, carotenoids, flavonoids, etc.), and the role of the hormones irisin and melatonin in the redox homeostasis of animal and human cells. The correlations between the deviation from optimal redox conditions and inflammation, allergic, aging and autoimmune responses are discussed. Special attention is given to the vascular system, kidney, liver and brain oxidative stress processes. The role of hydrogen peroxide as an intracellular and paracrine signal molecule is also reviewed. The cyanotoxins β-N-methylamino-l-alanine (BMAA), cylindrospermopsin, microcystins and nodularins are introduced as potentially dangerous food and environment pro-oxidants. Full article

The neurotoxin β-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid produced by cyanobacteria. Non-neuronal toxicity of BMAA is poorly studied with a reported increase in reactive oxygen species and a decrease in the antioxidant capacity of liver, kidney, and colorectal adenocarcinoma cells. The aim of this research is to study the toxicity of BMAA (0.1–1 mM) on mitochondria and submitochondrial particles with ATPase activity, on the semicarbazide-sensitive amino oxidases (SSAOs) activity of rat liver, and on an in vitro model containing functionally active excitable tissues—regularly contracting heart muscle preparation with a preserved autonomic innervation. For the first time the BMAA-dependent inhibition of SSAO activity, the elimination of the positive inotropic effect of adrenergic innervation, and the direct and reversible inhibition of adrenaline signaling in ventricular myocytes with 1 mM BMAA were observed. Additionally, it is confirmed that 1 mM BMAA can activate mitochondrial ATPase indirectly. It is concluded that a higher dose of BMAA may influence multiple physiological and pathological processes as it slows down the degradation of biogenic amines, downregulates the sympathetic neuromediation, and embarrasses the cell signaling of adrenergic receptors. Full article

In recent years, the consumption of blue-green algae (BGA) dietary supplements is increasing because of their health benefits. However, cyanobacteria can produce cyanotoxins, which present serious health risks. In this work we propose hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry (HILIC-MS/MS) to determine cyanotoxins in BGA dietary supplements. Target toxins, including microcystin-leucine-arginine (MC-LR) and microcystin-arginine-arginine (MC-RR), nodularin, anatoxin-a and three non-protein amino acids, β-N-methylamino-L-alanine (BMAA), 2,4-diaminobutyric acid (DAB) and N-(2-aminoethyl)glycine (AEG), were separated using a SeQuant ZIC-HILIC column. Cyanotoxin extraction was based on solid–liquid extraction (SLE) followed by a tandem-solid phase extraction (SPE) procedure using Strata-X and mixed-mode cation-exchange (MCX) cartridges. The method was validated for BGA dietary supplements obtaining quantification limits from 60 to 300 µg·kg⁻¹. Nine different commercial supplements were analyzed, and DAB, AEG, and MCs were found in some samples, highlighting the relevance of monitoring these substances as precaution measures for the safe consumption of these products. Full article

In the present review we have discussed the occurrence of β-N-methylamino-L-alanine (BMAA) and its natural isomers, and the organisms and sample types in which the toxin(s) have been detected. Further, the review discusses general pathogenic mechanisms of neurodegenerative diseases, and how modes of action of BMAA fit in those mechanisms. The biogeography of BMAA occurrence presented here contributes to the planning of epidemiological research based on the geographical distribution of BMAA and human exposure. Analysis of BMAA mechanisms in relation to pathogenic processes of neurodegeneration is used to critically assess the potential significance of the amino acid as well as to identify gaps in our understanding. Taken together, these two approaches provide the basis for the discussion on the potential role of BMAA as a secondary factor in neurodegenerative diseases, the rationale for further research and possible directions the research can take, which are outlined in the conclusions. Full article

β-N-methylamino L-alanine (BMAA) is a neurotoxin linked to high incidences of neurodegenerative disease. The toxin, along with two of its common isomers, 2,4-diaminobuytric acid (2,4-DAB) and N-(2-aminoethyl)glycine (AEG), is produced by multiple genera of cyanobacteria worldwide. Whilst there are many reports of locations and species of cyanobacteria associated with the production of BMAA during a bloom, there is a lack of information tracking changes in concentration across a single bloom event. This study aimed to measure the concentrations of BMAA and its isomers through the progression and end of a cyanobacteria bloom event using liquid chromatography-triple quadrupole-mass spectrometry. BMAA was detected in all samples analysed, with a decreasing trend observed as the bloom progressed. BMAA’s isomers were also detected in all samples, however, they did not follow the same decreasing pattern. This study highlights the potential for current sampling protocols that measure a single time point as representative of a bloom’s overall toxin content to underestimate BMAA concentration during a bloom event. Full article

Research interest in a non-protein amino acid β-N-methylamino-L-alanine (BMAA) arose due to the discovery of a connection between exposure to BMAA and the occurrence of neurodegenerative diseases. Previous reviews on this topic either considered BMAA as a risk factor for neurodegenerative diseases or focused on the problems of detecting BMAA in various environmental samples. Our review is devoted to a wide range of fundamental biological problems related to BMAA, including the molecular mechanisms of biological activity of BMAA and the complex relationships between producers of BMAA and the environment in various natural ecosystems. At the beginning, we briefly recall the most important facts about the producers of BMAA (cyanobacteria, microalgae, and bacteria), the pathways of BMAA biosynthesis, and reliable methods of identification of BMAA. The main distinctive feature of our review is a detailed examination of the molecular mechanisms underlying the toxicity of BMAA to living cells. A brand new aspect, not previously discussed in any reviews, is the effect of BMAA on cyanobacterial cells. These recent studies, conducted using transcriptomics and proteomics, revealed potent regulatory effects of BMAA on the basic metabolism and cell development of these ancient photoautotrophic prokaryotes. Exogenous BMAA strongly influences cell differentiation and primary metabolic processes in cyanobacteria, such as nitrogen fixation, photosynthesis, carbon fixation, and various biosynthetic processes involving 2-oxoglutarate and glutamate. Cyanobacteria were found to be more sensitive to exogenous BMAA under nitrogen-limited growth conditions. We suggest a hypothesis that this toxic diaminoacid can be used by phytoplankton organisms as a possible allelopathic tool for controlling the population of cyanobacterial cells during a period of intense competition for nitrogen and other resources in various ecosystems. Full article

Cyanotoxins are toxic metabolites produced by most cyanobacteria. In recent years, the occurrence of cyanobacterial blooms in aquatic ecosystems has temporally and spatially increased because of nutrient oversupply caused by human and also by climatic changes. This increase has a negative impact on water quality, ecosystem integrity, and human health. Cyanotoxins constitute a group of compounds with diverse physicochemical properties and their presence in drinkable, fishable, and recreational water is the main health-damaging cause. They are also able to bioaccumulate in plants and vegetables irrigated with contaminated water. Research on the development of suitable analytical methods is needed to establish early-warning strategies for the improved protectionof humans and ecosystems health. Liquid chromatography coupled with mass spectrometry (LC-MS) has been the preferred option for the control of these compounds, mainly using reverse-phase mode or hydrophilic interaction liquid chromatography (HILIC) in order to separate multiclass cyanotoxins of varying polarity, which cannot be handled by the commonly used reverse phase columns. In this work, we propose the use of capillary electrophoresis (CE) coupled with tandem mass spectrometry using triple quadrupole and positive electrospray ionization (CE-(ESI)-MS/MS) to determine a mixture of cyanotoxins with different polarity. CE is an advantageous alternative to LC given its short analysis times, high resolution, low sample and reagent volumes, and the use of silica capillaries and buffers as separation media, resulting in lower cost and low environmental impact. Moreover, CE allows the analysis of molecules hardly affordable by LC, such as polar and very similar compounds (e.g., isomers). The method is designed for the simultaneous determination of eight cyanotoxins belonging to three different classes: cyclic peptides (microcystin-LR, microcystin-RR, and nodularin), alkaloids (cylindrospermopsin, anatoxin-a), and three non-protein amino acids isomers (β-methylamino-L-alanine, 2,4-diaminobutyric acid, and N-(2-aminoethyl) glycine). Separation was achieved using an acidic background electrolyte (BGE) consisting in 2 M of formic acid (FA) and 20% acetonitrile in water. The proper separation and resolution of the three non-protein amino acid isomers was one of the main challenges of the method. This was overcome by applying a voltage of 30 kV in a 90 cm length capillary at 20 °C. Parameters affecting MS detection and the sheath–liquid interface were also studied. Finally, the fixed values were: a sheath gas flow rate of 5 L/min at 195 °C; sheath–liquid consists of MeOH/H2O/FA (50:49.95:0.05 v/v/v), a flow rate of 15 μL/min; and a nozzle voltage of 2000 V; N₂ dry gas rate of 11 L/min at 150 °C; a nebulizer pressure of 10 psi; and a capillary voltage of 2000 V. Online pre-concentration approaches were tested in order to achieve higher sensitivity, obtaining a enrichment factor of 4 with a mixed technique of pH-junction and Field Amplied Sample Stacking (FASS). Full article

Neurotoxin β-N-methylamino-L-alanine (BMAA) is hypothesized as an important pathogenic factor for neurodegenerative diseases such as amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS-PDC). Comparative study on the accuracy of BMAA analyzed by the regular LC-MS/MS methods is still limited for different biological matrices. In this study, a free-BMAA sample of cyanobacterium and BMAA-containing positive samples of diatom, mussel, scallop, and oyster were extracted with varied extraction ratios (ER) ranging from 1:20 to 1:2000. These extracts were then purified by MCX cartridges. After SPE purification, these different biological samples were analyzed by two common LC-MS/MS analysis methods, a direct analysis without derivatization by a hydrophilic interaction liquid chromatography (HILIC)-MS/MS and pre-column 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatization combined with a C18 column. The results suggested that the recoveries of BMAA spiked in the cyanobacterial sample were close to 100% in the total soluble form extracts with the ER of 1:100 (g/mL) and the precipitated bound form extracts with the ER of 1:500. The recommended ER for the precipitated bound form of BMAA in diatoms and the total soluble form of BMAA in mollusks are 1:500 and 1:50, respectively. The quantitative results determined by the AQC derivatization method were lower than those determined by the direct analysis of the HILIC method in diatom and mollusk samples. The results of the HILIC method without the derivatization process were closer to the true value of BMAA in cyanobacteria. This work contributes to the performance of the solid-phase extraction (SPE) purification protocol and the accuracy of BMAA analysis by LC-MS/MS in diverse biological samples. Full article