saxitoxin and anatoxin-a

Toxic cyanobacteria are a concern worldwide because they can adversely affect humans, animals, and ecosystems. However, neurotoxins produced by freshwater cyanobacteria are understudied relative to microcystin. Thus, the objective of this critical review was to provide a comprehensive examination of the modes of action, production, fate, and occurrence of the freshwater neurotoxins anatoxin-a and saxitoxin as they relate to human, animal, and ecosystem health. Literature on freshwater anatoxin-a and saxitoxin was obtained and reviewed for both laboratory and field studies. Current (2020) research identifies as many as 41 anatoxin-a producing species and 15 saxitoxin-producing species of freshwater cyanobacteria. Field studies indicate that anatoxin-a and saxitoxin have widespread distribution, and examples are given from every continent except Antarctica. Human and animal health concerns can range from acute to chronic. However, few researchers studied chronic or sublethal effects of freshwater exposures to anatoxin-a or saxitoxin. Ecosystem health also is a concern, as the effects of toxicity may be far reaching and include consequences throughout the food web. Several gaps in knowledge were identified for anatoxin-a and saxitoxin, including triggers of production and release, environmental fate and degradation, primary and secondary exposure routes, diel variation, food web effects, effects of cyanotoxin mixtures, and sublethal health effects on individual organisms and populations. Despite the gaps, this critical review facilitates our current understanding of freshwater neurotoxins and thus can serve to `` guide future research on anatoxin-a, saxitoxin, and other cyanotoxins.

Topics: Animals; Antarctic Regions; Bacterial Toxins; Cyanobacteria Toxins; Ecosystem; Fresh Water; Humans; Microcystins; Neurotoxins; Saxitoxin; Tropanes

Cyanobacteria are capable of thriving in almost all environments. Recent changes in climatic conditions due to increased human activities favor the occurrence and severity of harmful cyanobacterial bloom all over the world. Knowledge of the regulation of cyanotoxins by the various environmental factors is essential for effective management of toxic cyanobacterial bloom. In recent years, progress in the field of molecular mechanisms involved in cyanotoxin production has paved the way for assessing the role of various factors on the cyanotoxin production. In this review, we present an overview of the influence of various environmental factors on the production of major group of cyanotoxins, including microcystins, nodularin, cylindrospermopsin, anatoxins and saxitoxins.

Topics: Alkaloids; Animals; Bacterial Toxins; Climate Change; Cyanobacteria; Cyanobacteria Toxins; Environment; Humans; Marine Toxins; Microcystins; Peptides, Cyclic; Saxitoxin; Tropanes; Uracil

The treatment of cyanobacterial metabolites can consume many resources for water authorities which can be problematic especially with the recent shift away from chemical- and energy-intensive processes towards carbon and climate neutrality. In recent times, there has been a renaissance in biological treatment, in particular, biological filtration processes, for cyanobacteria metabolite removal. This in part, is due to the advances in molecular microbiology which has assisted in further understanding the biodegradation processes of specific cyanobacteria metabolites. However, there is currently no concise portfolio which captures all the pertinent information for the biological treatment of a range of cyanobacterial metabolites. This review encapsulates all the relevant information to date in one document and provides insights into how biological treatment options can be implemented in treatment plants for optimum cyanobacterial metabolite removal.

Topics: Alkaloids; Animals; Bacterial Toxins; Biodegradation, Environmental; Camphanes; Cyanobacteria; Cyanobacteria Toxins; Filtration; Humans; Microcystins; Naphthols; Peptides, Cyclic; Saxitoxin; Tropanes; Uracil; Water Purification

Alkaloid containing plants represent a heterogeneous group both taxonomically and chemically, a basic nitrogen being the unifying factor for the various classes. As most alkaloids are extremely toxic, organisms containing them do not feature strongly in medicine but they have always been important in the allopathic system. Typical alkaloids are derived from plant sources, they are basic, they contain one or more nitrogen, and they usually have marked physiological actions in humans or other mammalian species. This review will present various alkaloids generated by cyanobacteria, highlighting their complex structures, powerful bioactivities, and pharmacological properties. The main groups of cyanobacterial alkaloids include the neuromuscular transmission blocker anatoxins, the ion channel blocker saxitoxins, the degenerated amino acid β-methylamino-L-alanine, the protein synthesis inhibitor guanidine alkaloid cylindrospermopsins, and cyanobacterial indol alkaloids with antiviral, antifungal, and cytotoxic activity.

Topics: Alkaloids; Bacterial Toxins; Cholinesterases; Cyanobacteria; Cyanobacteria Toxins; Indoles; Protein Biosynthesis; Receptors, Nicotinic; Saxitoxin; Sodium Channels; Tropanes; Uracil

Topics: Alkaloids; Amino Acids, Diamino; Animals; Bacterial Toxins; Cyanobacteria; Cyanobacteria Toxins; Eutrophication; Humans; Marine Toxins; Microcystins; Peptides, Cyclic; Pharmacokinetics; Public Health; Saxitoxin; Tropanes; Uracil

Topics: Alkaloids; Animals; Bacterial Proteins; Bacterial Toxins; Biological Evolution; Cyanobacteria; Cyanobacteria Toxins; Eutrophication; Fresh Water; Gene Expression; Genes, Bacterial; Genomics; Humans; Marine Toxins; Microcystins; Peptide Synthases; Peptides, Cyclic; Saxitoxin; Tropanes; Uracil

Poisoning of livestock by toxic cyanobacteria was first reported in the 19th century, and throughout the 20th century cyanobacteria-related poisonings of livestock and wildlife in all continents have been described. Some mass mortality events involving unrelated fauna in prehistoric times have also been attributed to cyanotoxin poisoning; if correct, this serves as a reminder that toxic cyanobacteria blooms predate anthropogenic manipulation of the environment, though there is probably general agreement that human intervention has led to increases in the frequency and extent of cyanobacteria blooms. Many of the early reports of cyanobacteria poisoning were anecdotal and circumstantial, albeit with good descriptions of the appearance and behaviour of cyanobacteria blooms that preceded or coincided with illness and death in exposed animals. Early necropsy findings of hepatotoxicity were subsequently confirmed by experimental investigations. More recent reports supplement clinical and post-mortem findings with investigative chemistry techniques to identify cyanotoxins in stomach contents and tissue fluids.

Topics: Alkaloids; Animals; Animals, Domestic; Animals, Wild; Bacterial Toxins; Birds; Cyanobacteria; Cyanobacteria Toxins; Eutrophication; History, 20th Century; History, 21st Century; History, Ancient; Marine Toxins; Microcystins; Peptides, Cyclic; Saxitoxin; Tropanes; Uracil

Blue-green algae are found in lakes, ponds, rivers and brackish waters throughout the world. In case of excessive growth such as bloom formation, these bacteria can produce inherent toxins in quantities causing toxicity in mammals, including humans. These cyanotoxins include cyclic peptides and alkaloids. Among the cyclic peptides are the microcystins and the nodularins. The alkaloids include anatoxin-a, anatoxin-a(S), cylindrospermopsin, saxitoxins (STXs), aplysiatoxins and lyngbyatoxin. Both biological and chemical methods are used to determine cyanotoxins. Bioassays and biochemical assays are nonspecific, so they can only be used as screening methods. HPLC has some good prospects. For the subsequent detection of these toxins different detectors may be used, ranging from simple UV-spectrometry via fluorescence detection to various types of MS. The main problem in the determination of cyanobacterial toxins is the lack of reference materials of all relevant toxins. In general, toxicity data on cyanotoxins are rather scarce. A majority of toxicity data are known to be of microcystin-LR. For nodularins, data from a few animal studies are available. For the alkaloids, limited toxicity data exist for anatoxin-a, cylindrospermopsin and STX. Risk assessment for acute exposure could be relevant for some types of exposure. Nevertheless, no acute reference doses have formally been derived thus far. For STX(s), many countries have established tolerance levels in bivalves, but these limits were set in view of STX(s) as biotoxins, accumulating in marine shellfish. Official regulations for other cyanotoxins have not been established, although some (provisional) guideline values have been derived for microcystins in drinking water by WHO and several countries.

Topics: Alkaloids; Bacterial Toxins; Biodegradation, Environmental; Cyanobacteria; Cyanobacteria Toxins; Lyngbya Toxins; Marine Toxins; Microcystins; Peptides, Cyclic; Saxitoxin; Tropanes; Uracil

Cyanobacteria can produce cyanotoxins such as microcystin-LR (MC), saxitoxin (STX), and anatoxin-a (ANTX-a) which are harmful to humans and other animals. Individual removal efficiencies of STX and ANTX-a by powdered activated carbon (PAC) was investigated, as well as when MC-LR and cyanobacteria were present. Experiments were conducted with distilled water and then source water, using the PAC dosages, rapid mix/flocculation mixing intensities and contact times of two drinking water treatment plants in northeast Ohio. At pH 8 and 9, STX removal was 47%-81% in distilled water and 46%-79% in source water, whereas it was 0-28% for pH 6 in distilled water and 31%-52% in source water. When 1.6 µg/L or 20 µg/L MC-LR was present with STX, STX removal was increased with PAC simultaneously removing 45%-65% of the 1.6 µg/L MC-LR and 25%-95% of the 20 µg/L MC-LR depending on the pH. ANTX-a removal at pH 6 was 29%-37% for distilled water and 80% for source water, whereas it was 10%-26% for pH 8 in distilled water and 28% for pH 9 in source water. The presence of cyanobacteria cells decreased ANTX-a removal by at least 18%. When 20 µg/L MC-LR was present with ANTX-a in source water, 59%-73% ANTX-a and 48%-77% of MC-LR was removed at pH 9 depending on the PAC dose. In general, a higher PAC dose led to higher cyanotoxin removals. This study also documented that multiple cyanotoxins can be effectively removed by PAC for water at pH's between 6 and 9.

Topics: Charcoal; Cyanobacteria; Cyanobacteria Toxins; Humans; Microcystins; Saxitoxin

The effect of rising CO

Topics: Carbon Dioxide; Cyanobacteria; Cyanobacteria Toxins; Ecosystem; Microcystins; Nitrogen; Nitrogen Fixation; Saxitoxin

Cyanobacteria can form dense blooms under specific environmental conditions, and some species produce secondary metabolites known as cyanotoxins, which present significant risks to public health and the environment. Identifying toxins produced by cyanobacteria present in surface water and fish is critical to ensuring high quality food and water for consumption, and protectionn of recreational uses. Current analytical screening methods typically focus on one class of cyanotoxins in a single matrix and rarely include saxitoxin. Thus, a cross-class screening method for microcystins, nodularin, anatoxin-a, cylindrospermopsin, and saxitoxin was developed to examine target analytes in environmental water and fish tissue. This was done, due to the broad range of cyanotoxin physicochemical properties, by pairing two extraction and separation techniques to improve isolation and detection. For the first time a zwitterionic hydrophilic interaction liquid chromatography column was evaluated to separate anatoxin-a, cylindrospermopsin, and saxitoxin, demonstrating greater sensitivity for all three compounds over previous techniques. Further, the method for microcystins, nodularin, anatoxin-a, and cylindrospermopsin were validated using isotopically labeled internal standards, again for the first time, resulting in improved compensation for recovery bias and matrix suppression. Optimized extractions for water and fish tissue can be extended to other congeners in the future. These improved separation and isotope dilution techniques are a launching point for more complex, non-targeted analyses, with preliminary targeted screening.

Topics: Alkaloids; Animals; Bacterial Toxins; Chromatography, Liquid; Cyanobacteria; Cyanobacteria Toxins; Environmental Monitoring; Fishes; Isotopes; Marine Toxins; Microcystins; Peptides, Cyclic; Saxitoxin; Tandem Mass Spectrometry; Tropanes; Uracil; Water

Last decades, cyanobacterial blooms have been commonly reported in Russia. Among the boom-forming species, potential toxin producers have been identified. The aim of this paper was to study the presence of neurotoxic compounds - saxitoxins and anatoxin-a - in water bodies from different regions of Russia. We also made attempts to identify the neurotoxin-producing genera. The good convergence of the results obtained by light microscopy, PCR and LC-MS/MS analyses indicated the presence of active neurotoxin producing species in all investigated water bodies. Saxitoxin was detected in phytoplankton from 4 water bodies in Central European Russia and West Siberia, including lake and reservoirs used as a source for potable water. The water bodies differed with the respect of saxitoxin producers which belonged to Aphanizomenon and/or Dolichospermum genera. For the first time, we obtained quantitative data on the intracellular saxitoxin concentration in Russian freshwaters using LC-MS/MS. Anatoxin-a was detected only in lakes of Northwestern Russia. In the eutrophic shallow Lower Suzdal Lake, Aphanizomenon was the stated anatoxin-a-producing genus. In the large shallow artificial hypertrophic Sestroretskij Razliv Lake, it was very likely that both dominant species - Aphanizomenon flos-aquae and Dolichospermum planctonicum - were anatoxin-a producers.

Topics: Aphanizomenon; Chromatography, Liquid; Cyanobacteria; Cyanobacteria Toxins; Environmental Monitoring; Fresh Water; Mass Spectrometry; Neurotoxins; Russia; Saxitoxin; Tropanes

A new analytical method was developed for the detection of alkaloid cyanotoxins in harmful algal blooms. The detection of the nonproteinogenic amino acid β-N-methylamino-L-alanine (BMAA) and two of its conformation isomers, 2,4-diaminobutyric acid (DAB) and N-(2-aminoethyl) glycine (AEG), as well as three alkaloid cyanotoxins, anatoxin-a (ANA-a), cylindrospermopsin (CYN), and saxitoxin (STX), is presented. The use of a chemical derivatization with dansyl chloride (DNS) allows easier separation with reversed phase liquid chromatography. Detection with high-resolution mass spectrometry (HRMS) with the Q-Exactive enables high selectivity with specific fragmentation as well as exact mass detection, reducing considerably the possibilities of isobaric interferences. Previous to analysis, a solid phase extraction (SPE) step is used for purification and preconcentration. After DNS derivatization, samples are submitted to ultra high-performance liquid chromatography coupled with heated electrospray ionisation and the Q-Exactive mass spectrometer (UHPLC-HESI-HRMS). With an internal calibration using isotopically-labeled DAB-D3, the method was validated with good linearity (R (2)  > 0.998), and method limits of detection and quantification (MLD and MLQ) for target compounds ranged from 0.007 to 0.01 μg L(-1) and from 0.02 to 0.04 μg L(-1), respectively. Accuracy and within-day/between-days variation coefficients were below 15%. SPE recovery values ranged between 86 and 103%, and matrix effects recovery values ranged between 75 and 96%. The developed analytical method was successfully validated with 12 different lakes samples, and concentrations were found ranging between 0.009 and 0.3 μg L(-1) except for STX which was not found in any sample.

Topics: Alkaloids; Amino Acids, Diamino; Bacterial Toxins; Chromatography, High Pressure Liquid; Cyanobacteria; Cyanobacteria Toxins; Dansyl Compounds; Environmental Monitoring; Eutrophication; Lakes; Limit of Detection; Mass Spectrometry; Saxitoxin; Solid Phase Extraction; Tropanes; Uracil; Water Pollution, Chemical

Freshwater and brackish microalgal toxins, such as microcystins, cylindrospermopsins, paralytic toxins, anatoxins or other neurotoxins are produced during the overgrowth of certain phytoplankton and benthic cyanobacteria, which includes either prokaryotic or eukaryotic microalgae. Although, further studies are necessary to define the biological role of these toxins, at least some of them are known to be poisonous to humans and wildlife due to their occurrence in these aquatic systems. The World Health Organization (WHO) has established as provisional recommended limit 1μg of microcystin-LR per liter of drinking water. In this work we present a microsphere-based multi-detection method for five classes of freshwater and brackish toxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), anatoxin-a (ANA-a), saxitoxin (STX) and domoic acid (DA). Five inhibition assays were developed using different binding proteins and microsphere classes coupled to a flow-cytometry Luminex system. Then, assays were combined in one method for the simultaneous detection of the toxins. The IC50's using this method were 1.9±0.1μg L(-1) MC-LR, 1.3±0.1μg L(-1) CYN, 61±4μg L(-1) ANA-a, 5.4±0.4μg L(-1) STX and 4.9±0.9μg L(-1) DA. Lyophilized cyanobacterial culture samples were extracted using a simple procedure and analyzed by the Luminex method and by UPLC-IT-TOF-MS. Similar quantification was obtained by both methods for all toxins except for ANA-a, whereby the estimated content was lower when using UPLC-IT-TOF-MS. Therefore, this newly developed multiplexed detection method provides a rapid, simple, semi-quantitative screening tool for the simultaneous detection of five environmentally important freshwater and brackish toxins, in buffer and cyanobacterial extracts.

Topics: Alkaloids; Bacterial Toxins; Cyanobacteria; Cyanobacteria Toxins; Flow Cytometry; Fresh Water; Kainic Acid; Marine Toxins; Microalgae; Microcystins; Microspheres; Saxitoxin; Tropanes; Uracil

Several freshwater cyanobacteria species have the capability to produce toxic compounds, frequently referred to as cyanotoxins. The most prevalent of these cyanotoxins is microcystin LR. Recognizing the potential health risk, France, Italy, Poland, Australia, Canada, and Brazil have set either standards or guidelines for the amount of microcystin LR permissible in drinking water based on the World Health Organization guideline of one microg/L of microcystin LR. Recently, the United States Environmental Protection Agency has begun to evaluate the occurrence and health effects of cyanotoxins and their susceptibility to water treatment under the Safe Drinking Water Act through the Contaminant Candidate List (CCL). A recent update of the Contaminant Candidate List focuses research and data collection on the cyanotoxins microcystin LR, anatoxin-a, and cylindrospermopsin. Liquid Chromatography/Tandem-Mass Spectrometry (LC/MS/MS) is a powerful tool for the analysis of various analytes in a wide variety of matrices because of its sensitivity and selectivity. The use of smaller column media (sub 2 microm particles) was investigated to both improve the speed, sensitivity and resolution, and to quantify the CCL cyanotoxins, in a single analysis, using Ultra-Performance Liquid Chromatography (UPLC) combined with tandem mass spectrometry. Natural waters and spiked samples were analyzed to show proof-of-performance. The presented method was able to clearly resolve each of the cyanotoxins in less than eight minutes with specificity and high spike recoveries.

Topics: Alkaloids; Bacterial Toxins; Chromatography, High Pressure Liquid; Cyanobacteria; Cyanobacteria Toxins; Fresh Water; Marine Toxins; Microcystins; Saxitoxin; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Tropanes; Uracil; Water Pollutants, Chemical

Neurotoxic paralytic shellfish poisoning (PSP) toxins, anatoxin-a (ATX), and hepatotoxic cylindrospermopsin (CYN) have been detected in several lakes in northeast Germany during the last 2 decades. They are produced worldwide by members of the nostocalean genera Anabaena, Cylindrospermopsis, and Aphanizomenon. Although no additional sources of PSP toxins and ATX have been identified in German water bodies to date, the observed CYN concentrations cannot be produced solely by Aphanizomenon flos-aquae, the only known CYN producer in Germany. Therefore, we attempted to identify PSP toxin, ATX, and CYN producers by isolating and characterizing 92 Anabaena, Aphanizomenon, and Anabaenopsis strains from five lakes in northeast Germany. In a polyphasic approach, all strains were morphologically and phylogenetically classified and then tested for PSP toxins, ATX, and CYN by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) and screened for the presence of PSP toxin- and CYN-encoding gene fragments. As demonstrated by ELISA and LC-MS, 14 Aphanizomenon gracile strains from Lakes Melang and Scharmützel produced four PSP toxin variants (gonyautoxin 5 [GTX5], decarbamoylsaxitoxin [dcSTX], saxitoxin [STX], and neosaxitoxin [NEO]). GTX5 was the most prevalent PSP toxin variant among the seven strains from Lake Scharmützel, and NEO was the most prevalent among the seven strains from Lake Melang. The sxtA gene, which is part of the saxitoxin gene cluster, was found in the 14 PSP toxin-producing A. gracile strains and in 11 non-PSP toxin-producing Aphanizomenon issatschenkoi, A. flos-aquae, Anabaena planktonica, and Anabaenopsis elenkinii strains. ATX and CYN were not detected in any of the isolated strains. This study is the first confirming the role of A. gracile as a PSP toxin producer in German water bodies.

Topics: Alkaloids; Animals; Aphanizomenon; Bacterial Toxins; Base Sequence; Chromatography, High Pressure Liquid; Cyanobacteria; Cyanobacteria Toxins; DNA Primers; DNA, Bacterial; Enzyme-Linked Immunosorbent Assay; Fresh Water; Genes, Bacterial; Germany; Marine Toxins; Molecular Sequence Data; Phylogeny; Saxitoxin; Shellfish Poisoning; Tandem Mass Spectrometry; Tropanes; Uracil

It is clear from the literature that numerous methods are available for most cyanotoxins, although many publications on monitoring data indicate that the favored approach is the use proven, robust methods for individual toxins. The most effective approach is the utilization of a robust rapid screen, where positive samples are followed up by qualitative and quantitative analysis to provide the essential decision making data needed for successful management strategies (Fig. 2). Currently, rapid screens are available for microcystins, saxitoxins and anatoxin-a(s), whilst optimisation and validation is needed, many publications report good correlation with the mouse bioassay and HPLC. There is an urgent need for rapid, simple, and inexpensive assays for cylindrospermopsins, anatoxin-a and BMAA. Although methods exist for analysis of BMAA, the fact that a recent study showed 95% of cyanobacteria producing this, some at levels > 6,000 microg g(-1) dry wt, is of concern and rapid screening followed by robust analysis needed. An ideal approach would be a single method capable of extracting and detecting all cyanotoxins. Several publications describe such approaches using LC-MS, but as expected from a group of compounds with diverse chemistry, there are obvious limitations in recoveries during sample processing, chromatographic performance and sensitivity (Dahlmann et al. 2003, Dell'Aversano et al. 2004, Pietsch et al. 2001). Selection of methods must be based on the application requirements, equipment available and cost. For many organisations it may be more cost effective to out-source the occasional analysis. However, as the incidence of blooms appears to be increasing, the need for more rigorous monitoring is needed, sensible investment is needed to meet recommended guidelines. Most of the methods discussed in this paper are suitable for achieving this goal, although clean-up and concentration is usually necessary for physicochemical methods.

Topics: Alkaloids; Amino Acids, Diamino; Animals; Bacterial Toxins; Biological Assay; Chromatography, High Pressure Liquid; Cyanobacteria; Cyanobacteria Toxins; Environmental Monitoring; Eutrophication; Fresh Water; Immunoassay; Marine Toxins; Microcystins; Saxitoxin; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tropanes; Uracil

The cyanobacterial toxins of concern as potential human health hazards are those known to occur widely in drinking water sources, and therefore may be present in water for human use. The toxins include a diverse range of chemical compounds, with equally diverse toxic effects. These toxins are not limited to individual cyanobacterial species or genera, and all of the toxins of concern to human health are produced by multiple cyanobacterial species.

Topics: Alkaloids; Animals; Bacterial Toxins; Cyanobacteria; Cyanobacteria Toxins; Environmental Exposure; Eutrophication; Humans; Marine Toxins; Microcystins; Public Health; Saxitoxin; Tropanes; Uracil; Water Supply

The first identification of anatoxin-a in a French lotic system is reported. Rapid deaths of dogs occurred in 2003 after the animals drank water from the shoreline of the La Loue River in eastern France. Sediments, stones and macrophytes surfaces at the margin of the river were covered by a thick biofilm containing large quantities of several benthic species of filamentous, non-heterocystous cyanobacteria. Known cyanotoxins, such as microcystins, saxitoxins and anatoxins were screened from biofilm samples by biochemical and analytical assays. A compound with similar UV spectra to the anatoxin-a standard was detected by high-performance liquid chromatography (HPLC) coupled with photo-diode array detector. This toxin was further identified by HPLC coupled with a UV detector and by electrospray ionisation-Quadrupole-Time-Of-Flight mass spectrometer, and confirmed by tandem mass spectrometry. These two techniques were necessary to discriminate anatoxin-a in phenylalanine-containing matrices such as liver samples of poisoned dogs. The toxin and the aromatic amino acid, phenylalanine, present the same pseudomolecular ion at m/z 166, but have differing fragmentation patterns, retention times and UV spectra. Finally, several cyanobacterial strains were isolated from the green biofilm and tested for anatoxin-a production. Phormidium favosum was identified as a new anatoxin-a producing species.

Topics: Animals; Bacterial Toxins; Cell Line, Tumor; Cyanobacteria; Cyanobacteria Toxins; Dogs; Environmental Monitoring; France; Gastrointestinal Contents; Intestines; Liver; Marine Toxins; Mice; Microcystins; Neurotoxins; Peptides, Cyclic; Poisoning; Rivers; Saxitoxin; Tropanes