Cyanotoxins

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Marine and Freshwater Toxins".

Deadline for manuscript submissions: closed (31 March 2013) | Viewed by 71590

Special Issue Editor

Department of Chemistry and Biochemistry, Florida International University (FIU), 354/332 Marine Science, Biscayne Bay Campus, 3000 NE 151st St., North Miami, FL 33181, USA
Interests: cyanobacteria; toxins; bioactive compounds; zebrafish embryo model; natural products
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

One of the oldest groups of organisms known—from fossil records dating back more than 3.5 billion years—the cyanobacteria (or "blue-green algae") are recognized to produce a diverse repertoire of biologically active secondary metabolites. Occurring ubiquitously in both free-living and symbiotic form, and perhaps most conspicuously in aquatic habitats as part of so-called "harmful algal blooms" (HABs), several of these bioactive cyanobacterial metabolites have been clearly identified as "toxins" that negatively impact human, animal and ecosystem health—including acute toxicoses and chronic, long-term health effects—in association with toxigenic HABs, contamination of drinking water, transfer through food-webs and other potential exposure routes. Moreover, in light of global climate change, and particularly measurable rises in global temperature, as well as increased fluxes of certain nutrients (i.e., nitrates, phosphates) from pollutant run-off (e.g., fertilizers, sewage/waste) and other anthropogenic sources, it has been suggested that cyanobacteria—including toxin-producing taxa—and cyanobacterial HABs may be increasing in abundance, and thus represent an emerging human and environmental health concern. This special issue will present, through both primary research and comprehensive review papers, up-to-date findings on these so-called “cyanotoxins” particularly focusing on their chemistry and toxicology, as well as aspects (e.g., monitoring strategies) related to mitigating their potential health effects, and understanding of the ecological dynamics related to the toxins and their production.

Prof. Dr. John P. Berry
Guest Editor

Submission

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Keywords

  • cyanobacteria
  • toxins
  • cyanotoxins
  • harmful algal blooms
  • blue-green algae
  • toxicology
  • chemistry

Published Papers (7 papers)

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258 KiB  
Article
Canine Cyanotoxin Poisonings in the United States (1920s–2012): Review of Suspected and Confirmed Cases from Three Data Sources
by Lorraine C. Backer, Jan H. Landsberg, Melissa Miller, Kevin Keel and Tegwin K. Taylor
Toxins 2013, 5(9), 1597-1628; https://doi.org/10.3390/toxins5091597 - 24 Sep 2013
Cited by 98 | Viewed by 12269
Abstract
Cyanobacteria (also called blue-green algae) are ubiquitous in aquatic environments. Some species produce potent toxins that can sicken or kill people, domestic animals, and wildlife. Dogs are particularly vulnerable to cyanotoxin poisoning because of their tendency to swim in and drink contaminated water [...] Read more.
Cyanobacteria (also called blue-green algae) are ubiquitous in aquatic environments. Some species produce potent toxins that can sicken or kill people, domestic animals, and wildlife. Dogs are particularly vulnerable to cyanotoxin poisoning because of their tendency to swim in and drink contaminated water during algal blooms or to ingestalgal mats.. Here, we summarize reports of suspected or confirmed canine cyanotoxin poisonings in the U.S. from three sources: (1) The Harmful Algal Bloom-related Illness Surveillance System (HABISS) of the National Center for Environmental Health (NCEH), Centers for Disease Control and Prevention (CDC); (2) Retrospective case files from a large, regional veterinary hospital in California; and (3) Publicly available scientific and medical manuscripts; written media; and web-based reports from pet owners, veterinarians, and other individuals. We identified 231 discreet cyanobacteria harmful algal bloom (cyanoHAB) events and 368 cases of cyanotoxin poisoning associated with dogs throughout the U.S. between the late 1920s and 2012. The canine cyanotoxin poisoning events reviewed here likely represent a small fraction of cases that occur throughout the U.S. each year. Full article
(This article belongs to the Special Issue Cyanotoxins)
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1065 KiB  
Article
Limited Stability of Microcystins in Oligopeptide Compositions of Microcystis aeruginosa (Cyanobacteria): Implications in the Definition of Chemotypes
by Ramsy Agha, Samuel Cirés, Lars Wörmer and Antonio Quesada
Toxins 2013, 5(6), 1089-1104; https://doi.org/10.3390/toxins5061089 - 06 Jun 2013
Cited by 15 | Viewed by 9374
Abstract
The occurrence of diverse oligopeptides in cyanobacteria, including the cyanotoxins microcystins, has been recently used to classify individual clones into sub-specific oligopeptide chemotypes, whose composition and dynamics modulate microcystin concentrations in cyanobacterial blooms. Cyanobacterial chemotyping allows the study of the ecology of chemotypical [...] Read more.
The occurrence of diverse oligopeptides in cyanobacteria, including the cyanotoxins microcystins, has been recently used to classify individual clones into sub-specific oligopeptide chemotypes, whose composition and dynamics modulate microcystin concentrations in cyanobacterial blooms. Cyanobacterial chemotyping allows the study of the ecology of chemotypical subpopulations, which have been shown to possess dissimilar ecological traits. However, the stability of chemotypes under changing abiotic conditions is usually assumed and has not been assessed in detail. We monitored oligopeptide patterns of three strains of Microcystis aeruginosa under different nutrient and light conditions. MALDI-TOF MS revealed alterations in the microcystins signatures under N and P poor conditions and high light intensities (150 and 400 μmol photons m−2s−1). Variations in the general oligopeptide composition were caused by a gradual disappearance of microcystins with low relative intensity signals from the fingerprint. The extent of such variations seems to be closely related to physiological stress caused by treatments. Under identical clonal compositions, alterations in the oligopeptide fingerprint may be misinterpreted as apparent shifts in chemotype succession. We discuss the nature of such variations, as well as the consequent implications in the use of cyanobacterial chemotyping in studies at the subpopulation level and propose new guidance for the definition of chemotypes as a consistent subpopulation marker. Full article
(This article belongs to the Special Issue Cyanotoxins)
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375 KiB  
Article
Variations in the Microcystin Content of Different Fish Species Collected from a Eutrophic Lake
by Justine R. Schmidt, Mylynda Shaskus, John F. Estenik, Carl Oesch, Roman Khidekel and Gregory L. Boyer
Toxins 2013, 5(5), 992-1009; https://doi.org/10.3390/toxins5050992 - 15 May 2013
Cited by 50 | Viewed by 12171
Abstract
Microcystins produced from cyanobacteria can accumulate in fish tissues. Liquid chromatography coupled with tandem quadrupole mass spectrometry (LC-MS/MS) is an attractive alternative to immunoassays for the determination of low concentrations of microcystins in tissues. Fish taken from Grand Lake St. Marys, a eutrophic [...] Read more.
Microcystins produced from cyanobacteria can accumulate in fish tissues. Liquid chromatography coupled with tandem quadrupole mass spectrometry (LC-MS/MS) is an attractive alternative to immunoassays for the determination of low concentrations of microcystins in tissues. Fish taken from Grand Lake St. Marys, a eutrophic lake in Ohio, USA, were analyzed for microcystin-LR in their fillets using LC-MS/MS. Of 129 fish tested for microcystins, only black crappie (Pomoxis nigromaculatus) and common carp (Cyprinus carpio) tested positive for microcystin-LR. Less than 10% of Pomoxis and 7% of Cyprinus samples contained measurable levels of microcystin-LR. Statistical analysis yielded a p-value of 0.07 between Pomoxis and the pooled results of the other four fish species. However, this comparison was complicated by the large difference in sample size between species. Further sampling in Grand Lake St. Marys for microcystin-LR would help determine if microcystin-LR exposure occurs through foodweb transfer. Full article
(This article belongs to the Special Issue Cyanotoxins)
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439 KiB  
Article
Sedimentation Patterns of Toxin-Producing Microcystis Morphospecies in Freshwater Reservoirs
by Samuel Cirés, Lars Wörmer, David Carrasco and Antonio Quesada
Toxins 2013, 5(5), 939-957; https://doi.org/10.3390/toxins5050939 - 03 May 2013
Cited by 24 | Viewed by 6479
Abstract
Understanding the annual cycle of Microcystis is essential for managing the blooms of this toxic cyanobacterium. The current work investigated the sedimentation of microcystin-producing Microcystis spp. in three reservoirs from Central Spain during the summer and autumn of 2006 and 2007. We confirmed [...] Read more.
Understanding the annual cycle of Microcystis is essential for managing the blooms of this toxic cyanobacterium. The current work investigated the sedimentation of microcystin-producing Microcystis spp. in three reservoirs from Central Spain during the summer and autumn of 2006 and 2007. We confirmed remarkable settling fluxes during and after blooms ranging 106–109 cells m−2 d−1, which might represent 0.1%–7.6% of the organic matter settled. A comprehensive analysis of the Valmayor reservoir showed average Microcystis settling rates (0.04 d−1) and velocities (0.7 m d−1) that resembled toxin settling in the same reservoir and were above most reported elsewhere. M. aeruginosa settling rate was significantly higher than that of M. novacekii and M. flos-aquae. Despite the fact that colony sizes did not differ significantly in their average settling rates, we observed extremely high and low rates in large colonies (>5000 cells) and a greater influence of a drop in temperature on small colonies (<1000 cells). We found a 4–14 fold decrease in microcystin cell quota in settling Microcystis of the Cogotas and Valmayor reservoirs compared with pelagic populations, and the hypothetical causes of this are discussed. Our study provides novel data on Microcystis settling patterns in Mediterranean Europe and highlights the need for including morphological, chemotypical and physiological criteria to address the sedimentation of complex Microcystis populations. Full article
(This article belongs to the Special Issue Cyanotoxins)
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675 KiB  
Article
Dog Poisonings Associated with a Microcystis aeruginosa Bloom in the Netherlands
by Miquel Lürling and Elisabeth J. Faassen
Toxins 2013, 5(3), 556-567; https://doi.org/10.3390/toxins5030556 - 14 Mar 2013
Cited by 52 | Viewed by 9701
Abstract
In early autumn 2011, three dogs died after they had been exposed to a Microcystis aeruginosa bloom on Lake Amstelmeer, The Netherlands. The cyanobacterial scum from the lake contained up to 5.27 × 103 μg g−1 dry-weight microcystin, the vomit of [...] Read more.
In early autumn 2011, three dogs died after they had been exposed to a Microcystis aeruginosa bloom on Lake Amstelmeer, The Netherlands. The cyanobacterial scum from the lake contained up to 5.27 × 103 μg g−1 dry-weight microcystin, the vomit of one of the dogs contained on average 94 µg microcystin g−1 dry-weight. In both cases, microcystin-LR was the most abundant variant. This is the first report of dog deaths associated with a Microcystis bloom and microcystin poisoning in The Netherlands. Full article
(This article belongs to the Special Issue Cyanotoxins)
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315 KiB  
Article
Within-Mat Variability in Anatoxin-a and Homoanatoxin-a Production among Benthic Phormidium (Cyanobacteria) Strains
by Susanna A. Wood, Francine M. J. Smith, Mark W. Heath, Thomas Palfroy, Sally Gaw, Roger G. Young and Ken G. Ryan
Toxins 2012, 4(10), 900-912; https://doi.org/10.3390/toxins4100900 - 19 Oct 2012
Cited by 65 | Viewed by 9225
Abstract
Benthic Phormidium mats can contain high concentrations of the neurotoxins anatoxin-a and homoanatoxin-a. However, little is known about the co-occurrence of anatoxin-producing and non-anatoxin-producing strains within mats. There is also no data on variation in anatoxin content among toxic genotypes isolated from the [...] Read more.
Benthic Phormidium mats can contain high concentrations of the neurotoxins anatoxin-a and homoanatoxin-a. However, little is known about the co-occurrence of anatoxin-producing and non-anatoxin-producing strains within mats. There is also no data on variation in anatoxin content among toxic genotypes isolated from the same mat. In this study, 30 Phormidium strains were isolated from 1 cm2 sections of Phormidium-dominated mats collected from three different sites. Strains were grown to stationary phase and their anatoxin-a, homoanatoxin-a, dihydroanatoxin-a and dihydrohomoanatoxin-a concentrations determined using liquid chromatography-mass spectrometry. Each strain was characterized using morphological and molecular (16S rRNA gene sequences) techniques. Eighteen strains produced anatoxin-a, dihydroanatoxin-a or homoanatoxin-a. Strains isolated from each mat either all produced toxins, or were a mixture of anatoxin and non-anatoxin-producing genotypes. Based on morphology these genotypes could not be separated. The 16S rRNA gene sequence comparisons showed a difference of at least 17 nucleotides among anatoxin and non-anatoxin-producing strains and these formed two separate sub-clades during phylogenetic analysis. The total anatoxin concentration among toxic strains varied from 2.21 to 211.88 mg kg−1 (freeze dried weight), representing a 100 fold variation in toxin content. These data indicate that both the relative abundance of anatoxin and non-anatoxin-producing genotypes, and variations in anatoxin producing capability, can influence the overall toxin concentration of benthic Phormidium mat samples. Full article
(This article belongs to the Special Issue Cyanotoxins)
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687 KiB  
Case Report
Treatment of Cyanobacterial (Microcystin) Toxicosis Using Oral Cholestyramine: Case Report of a Dog from Montana
by Kelly A. Rankin, Karen A. Alroy, Raphael M. Kudela, Stori C. Oates, Michael J. Murray and Melissa A. Miller
Toxins 2013, 5(6), 1051-1063; https://doi.org/10.3390/toxins5061051 - 29 May 2013
Cited by 24 | Viewed by 11133
Abstract
A two and a half year old spayed female Miniature Australian Shepherd presented to a Montana veterinary clinic with acute onset of anorexia, vomiting and depression. Two days prior, the dog was exposed to an algal bloom in a community lake. Within h, [...] Read more.
A two and a half year old spayed female Miniature Australian Shepherd presented to a Montana veterinary clinic with acute onset of anorexia, vomiting and depression. Two days prior, the dog was exposed to an algal bloom in a community lake. Within h, the animal became lethargic and anorexic, and progressed to severe depression and vomiting. A complete blood count and serum chemistry panel suggested acute hepatitis, and a severe coagulopathy was noted clinically. Feces from the affected dog were positive for the cyanobacterial biotoxin, microcystin-LA (217 ppb). The dog was hospitalized for eight days. Supportive therapy consisted of fluids, mucosal protectants, vitamins, antibiotics, and nutritional supplements. On day five of hospitalization, a bile acid sequestrant, cholestyramine, was administered orally. Rapid clinical improvement was noted within 48 h of initiating oral cholestyramine therapy. At 17 days post-exposure the dog was clinically normal, and remained clinically normal at re-check, one year post-exposure. To our knowledge, this is the first report of successful treatment of canine cyanobacterial (microcystin) toxicosis. Untreated microcystin intoxication is commonly fatal, and can result in significant liver damage in surviving animals. The clinical success of this case suggests that oral administration of cholestyramine, in combination with supportive therapy, could significantly reduce hospitalization time, cost-of-care and mortality for microcystin-poisoned animals Full article
(This article belongs to the Special Issue Cyanotoxins)
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