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Special Issue "Algal Toxins"

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A special issue of Marine Drugs (ISSN 1660-3397).

Deadline for manuscript submissions: closed (31 August 2011)

Special Issue Editor

Guest Editor
Prof. Dr. John P. Berry (Website)

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
Phone: 3059194569
Fax: +1 305 919 4030
Interests: cyanobacteria; toxins; bioactive compounds; zebrafish embryo model; natural products

Special Issue Information

Dear Colleagues,

Marine and freshwater algae are recognized to produce a diverse array of toxic or otherwise bioactive metabolites. These toxic metabolites are globally widespread, and humans and other animals can be exposed to them through both direct routes, including contamination of drinking water and recreational exposure, and indirect routes, including accumulation of these toxins by (and consequent contamination of) various species of fish, shellfish and other animals used as food. Exposure to these toxins has been linked to both acute health effects, including numerous cases of severe illness and mortality, as well as possible long-term health effects, ranging from higher incidence of certain cancers and neurodegenerative disease to prenatal developmental dysfunction. As such algal toxins are emerging as a potentially important human and environmental health concern. Accordingly, a growing number of studies have likewise emerged to address this issue. Areas of investigation particularly include (1) identification and characterization of new toxins; (2) genes and pathways for biosynthesis; (3) bioaccumulation in aquatic food-webs; (4) environmental and ecological factors that contribute to toxin production; (5) methods and technologies for effective detection and monitoring of toxins; (6) epidemiological studies to evaluate the human health impacts of toxins; and (7) strategies and technologies for mitigation of these threats to human health. In addition to their roles as toxins, a number of these bioactive metabolites have also been investigated with respect to possible development as drugs, or otherwise biomedically useful agents, addressing a range of pharmacological targets, as well as other applications with potential commercial importance, including herbicides and pesticides. This special issue will present a relevant sample of current studies investigating these various aspects of algal toxins.

Prof. Dr. John P. Berry
Guest Editor

Keywords

  • cyanobacteria
  • dinoflagellates
  • diatoms
  • harmful algal blooms
  • polyketides
  • non-ribsomal peptides
  • chemical ecology
  • ecotoxicology

Related Special Issue

Published Papers (17 papers)

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Research

Jump to: Review, Other

Open AccessArticle Characterization of Palytoxin Binding to HaCaT Cells Using a Monoclonal Anti-Palytoxin Antibody
Mar. Drugs 2013, 11(3), 584-598; doi:10.3390/md11030584
Received: 18 December 2012 / Revised: 12 January 2013 / Accepted: 15 February 2013 / Published: 26 February 2013
Cited by 10 | PDF Full-text (735 KB) | HTML Full-text | XML Full-text
Abstract
Palytoxin (PLTX) is the reference compound for a group of potent marine biotoxins, for which the molecular target is Na+/K+-ATPase. Indeed, ouabain (OUA), a potent blocker of the pump, is used to inhibit some PLTX effects in vitro [...] Read more.
Palytoxin (PLTX) is the reference compound for a group of potent marine biotoxins, for which the molecular target is Na+/K+-ATPase. Indeed, ouabain (OUA), a potent blocker of the pump, is used to inhibit some PLTX effects in vitro. However, in an effort to explain incomplete inhibition of PLTX cytotoxicity, some studies suggest the possibility of two different binding sites on Na+/K+-ATPase. Hence, this study was performed to characterize PLTX binding to intact HaCaT keratinocytes and to investigate the ability of OUA to compete for this binding. PLTX binding to HaCaT cells was demonstrated by immunocytochemical analysis after 10 min exposure. An anti-PLTX monoclonal antibody-based ELISA showed that the binding was saturable and reversible, with a Kd of 3 × 10−10 M. However, kinetic experiments revealed that PLTX binding dissociation was incomplete, suggesting an additional, OUA-insensitive, PLTX binding site. Competitive experiments suggested that OUA acts as a negative allosteric modulator against high PLTX concentrations (0.3–1.0 × 10−7 M) and possibly as a non-competitive antagonist against low PLTX concentrations (0.1–3.0 × 10−9 M). Antagonism was supported by PLTX cytotoxicity inhibition at OUA concentrations that displaced PLTX binding (1 × 10−5 M). However, this inhibition was incomplete, supporting the existence of both OUA-sensitive and -insensitive PLTX binding sites. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessArticle Accumulation, Biotransformation, Histopathology and Paralysis in the Pacific Calico Scallop Argopecten ventricosus by the Paralyzing Toxins of the Dinoflagellate Gymnodinium catenatum
Mar. Drugs 2012, 10(5), 1044-1065; doi:10.3390/md10051044
Received: 1 March 2012 / Revised: 10 April 2012 / Accepted: 18 April 2012 / Published: 9 May 2012
Cited by 4 | PDF Full-text (4668 KB) | HTML Full-text | XML Full-text
Abstract
The dinoflagellate Gymnodinium catenatum produces paralyzing shellfish poisons that are consumed and accumulated by bivalves. We performed short-term feeding experiments to examine ingestion, accumulation, biotransformation, histopathology, and paralysis in the juvenile Pacific calico scallop Argopecten ventricosus that consume this dinoflagellate. Depletion of [...] Read more.
The dinoflagellate Gymnodinium catenatum produces paralyzing shellfish poisons that are consumed and accumulated by bivalves. We performed short-term feeding experiments to examine ingestion, accumulation, biotransformation, histopathology, and paralysis in the juvenile Pacific calico scallop Argopecten ventricosus that consume this dinoflagellate. Depletion of algal cells was measured in closed systems. Histopathological preparations were microscopically analyzed. Paralysis was observed and the time of recovery recorded. Accumulation and possible biotransformation of toxins were measured by HPLC analysis. Feeding activity in treated scallops showed that scallops produced pseudofeces, ingestion rates decreased at 8 h; approximately 60% of the scallops were paralyzed and melanin production and hemocyte aggregation were observed in several tissues at 15 h. HPLC analysis showed that the only toxins present in the dinoflagellates and scallops were the N-sulfo-carbamoyl toxins (C1, C2); after hydrolysis, the carbamate toxins (epimers GTX2/3) were present. C1 and C2 toxins were most common in the mantle, followed by the digestive gland and stomach-complex, adductor muscle, kidney and rectum group, and finally, gills. Toxin profiles in scallop tissue were similar to the dinoflagellate; biotransformations were not present in the scallops in this short-term feeding experiment. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessArticle A Kinetic Study of Accumulation and Elimination of Microcystin-LR in Yellow Perch (Perca Flavescens) Tissue and Implications for Human Fish Consumption
Mar. Drugs 2011, 9(12), 2553-2571; doi:10.3390/md9122553
Received: 20 September 2011 / Revised: 15 November 2011 / Accepted: 2 December 2011 / Published: 8 December 2011
Cited by 5 | PDF Full-text (232 KB) | HTML Full-text | XML Full-text
Abstract
Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues [...] Read more.
Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues of consumers are important for determining the potential for microcystins to be transferred up the food web and for predicting potential human health impacts. The main objective of this work was to conduct laboratory experiments to investigate the kinetics of toxin accumulation in fish tissue. An oral route of exposure was employed in this study, in which juvenile yellow perch (Perca flavescens) were given a single oral dose of 5 or 20 μg of microcystin-LR (MC-LR) via food and accumulation in the muscle, liver, and tank water were measured over 24 h. Peak concentrations of the water soluble fraction of microcystin were generally observed 8–10 h after dosing in the liver and after 12–16 h in the muscle, with a rapid decline in both tissues by 24 h. Up to 99% of the total recoverable (i.e., unbound) microcystin was measured in the tank water by 16 h after exposure. The relatively rapid uptake and elimination of the unbound fraction of microcystin in the liver and muscle of juvenile yellow perch within 24 h of exposure indicates that fish consumption may not be a major route of human exposure to microcystin, particularly in the Great Lakes. Full article
(This article belongs to the Special Issue Algal Toxins)
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Open AccessArticle Antibacterial Activity of Marine and Black Band Disease Cyanobacteria against Coral-Associated Bacteria
Mar. Drugs 2011, 9(10), 2089-2105; doi:10.3390/md9102089
Received: 9 September 2011 / Revised: 29 September 2011 / Accepted: 14 October 2011 / Published: 24 October 2011
Cited by 12 | PDF Full-text (292 KB) | HTML Full-text | XML Full-text
Abstract
Black band disease (BBD) of corals is a cyanobacteria-dominated polymicrobial disease that contains diverse populations of heterotrophic bacteria. It is one of the most destructive of coral diseases and is found globally on tropical and sub-tropical reefs. We assessed ten strains of [...] Read more.
Black band disease (BBD) of corals is a cyanobacteria-dominated polymicrobial disease that contains diverse populations of heterotrophic bacteria. It is one of the most destructive of coral diseases and is found globally on tropical and sub-tropical reefs. We assessed ten strains of BBD cyanobacteria, and ten strains of cyanobacteria isolated from other marine sources, for their antibacterial effect on growth of heterotrophic bacteria isolated from BBD, from the surface mucopolysaccharide layer (SML) of healthy corals, and three known bacterial coral pathogens. Assays were conducted using two methods: co-cultivation of cyanobacterial and bacterial isolates, and exposure of test bacteria to (hydrophilic and lipophilic) cyanobacterial cell extracts. During co-cultivation, 15 of the 20 cyanobacterial strains tested had antibacterial activity against at least one of the test bacterial strains. Inhibition was significantly higher for BBD cyanobacteria when compared to other marine cyanobacteria. Lipophilic extracts were more active than co-cultivation (extracts of 18 of the 20 strains were active) while hydrophilic extracts had very limited activity. In some cases co-cultivation resulted in stimulation of BBD and SML bacterial growth. Our results suggest that BBD cyanobacteria are involved in structuring the complex polymicrobial BBD microbial community by production of antimicrobial compounds. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessArticle Seasonal Dynamics of Microcystis spp. and Their Toxigenicity as Assessed by qPCR in a Temperate Reservoir
Mar. Drugs 2011, 9(10), 1715-1730; doi:10.3390/md9101715
Received: 26 August 2011 / Revised: 15 September 2011 / Accepted: 26 September 2011 / Published: 29 September 2011
Cited by 9 | PDF Full-text (202 KB) | HTML Full-text | XML Full-text
Abstract
Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis [...] Read more.
Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis, were quantified to determine the genotypic composition of the natural Microcystis population. Correlations between limnological parameters, pH, water temperature, dissolved oxygen and conductivity and MC concentrations as well as Microcystis abundance were assessed. A negative significant correlation was observed between toxic (with mcy genes) to non-toxic (without mcy genes) genotypes ratio and the overall Microcystis density. The highest proportions of toxic Microcystis genotypes were found 4–6 weeks before and 8–10 weeks after the peak of the bloom, with the lowest being observed at its peak. These results suggest positive selection of non-toxic genotypes under favorable environmental growth conditions. Significant positive correlations could be found between quantity of toxic genotypes and MC concentration, suggesting that the method applied can be useful to predict potential MC toxicity risk. No significant correlation was found between the limnological parameters measured and MC concentrations or toxic genotypes proportions indicating that other abiotic and biotic factors should be governing MC production and toxic genotypes dynamics. The qPCR method here applied is useful to rapidly estimate the potential toxicity of environmental samples and so, it may contribute to the more efficient management of water use in eutrophic systems. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessArticle Intramolecular Modulation of Serine Protease Inhibitor Activity in a Marine Cyanobacterium with Antifeedant Properties
Mar. Drugs 2010, 8(6), 1803-1816; doi:10.3390/md8061803
Received: 15 April 2010 / Revised: 2 June 2010 / Accepted: 2 June 2010 / Published: 4 June 2010
Cited by 9 | PDF Full-text (562 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Extracts of the Floridian marine cyanobacterium Lyngbya cf. confervoides were found to deter feeding by reef fish and sea urchins (Diadema antillarum). This antifeedant activity may be a reflection of the secondary metabolite content, known to be comprised of many [...] Read more.
Extracts of the Floridian marine cyanobacterium Lyngbya cf. confervoides were found to deter feeding by reef fish and sea urchins (Diadema antillarum). This antifeedant activity may be a reflection of the secondary metabolite content, known to be comprised of many serine protease inhibitors. Further chemical and NMR spectroscopic investigation led us to isolate and structurally characterize a new serine protease inhibitor 1 that is formally derived from an intramolecular condensation of largamide D (2). The cyclization resulted in diminished activity, but to different extents against two serine proteases tested. This finding suggests that cyanobacteria can endogenously modulate the activity of their protease inhibitors. Full article
(This article belongs to the Special Issue Algal Toxins)
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Open AccessArticle Investigation of Pectenotoxin Profiles in the Yellow Sea (China) Using a Passive Sampling Technique
Mar. Drugs 2010, 8(4), 1263-1272; doi:10.3390/md8041263
Received: 21 February 2010 / Revised: 16 March 2010 / Accepted: 7 April 2010 / Published: 15 April 2010
Cited by 9 | PDF Full-text (309 KB) | HTML Full-text | XML Full-text
Abstract
Pectenotoxins (PTXs) are a group of lipophilic algal toxins. These toxins have been found in algae and shellfish from Japan, New Zealand, Ireland, Norway and Portugal. PTX profiles vary with geographic location of collection site. The aim of the present study was [...] Read more.
Pectenotoxins (PTXs) are a group of lipophilic algal toxins. These toxins have been found in algae and shellfish from Japan, New Zealand, Ireland, Norway and Portugal. PTX profiles vary with geographic location of collection site. The aim of the present study was to investigate PTX profiles from the Yellow Sea, China. The sampling location was within an aquatic farm (N36°12.428´, E120°17.826´) near the coast of Qingdao, China, in the Yellow Sea from 28July to 29August 2006. PTXs in seawater were determined using a solid phase adsorption toxin tracking (SPATT) method. PTXs were analyzed by HPLC-MSMS. PTX-2, PTX-2 sec acid (PTX-2 SA) and 7-epi-PTX-2 SA were found in seawater samples. The highest levels of PTXs (107 ng/g of resin PTX-2, 50 ng/g of resin PTX-2 SA plus 7-epi-PTX-2 SA) in seawater were found on 1 August, 2006. From 1 August to 29 August, the levels of PTX-2 and PTX-2 SA decreased. In the same area, the marine algae, Dinophysis acuminata was found in the seawater in the summer months of 2006. This indicated that Dinophysis acuumuta might be the original source of PTXs. PTX-11 and PTX-12a/b were not found in seawater. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessArticle Is Yessotoxin the Main Phycotoxin in Croatian Waters?
Mar. Drugs 2010, 8(3), 460-470; doi:10.3390/md8030460
Received: 21 January 2010 / Revised: 8 February 2010 / Accepted: 20 February 2010 / Published: 5 March 2010
Cited by 6 | PDF Full-text (247 KB) | HTML Full-text | XML Full-text
Abstract
With the aim of investigating whether yessotoxin (YTX) is responsible for diarrhetic shellfish poisoning (DSP) events in Croatian waters, three different methods were combined: a modified mouse bioassay (MBA) that discriminates YTX from other DSP toxins, the enzyme-linked immunosorbent assay method (ELISA) [...] Read more.
With the aim of investigating whether yessotoxin (YTX) is responsible for diarrhetic shellfish poisoning (DSP) events in Croatian waters, three different methods were combined: a modified mouse bioassay (MBA) that discriminates YTX from other DSP toxins, the enzyme-linked immunosorbent assay method (ELISA) and liquid chromatography-mass spectrometry (LC-MS/MS). Among 453 samples of mussels and seawater analyzed in 2007, 10 samples were DSP positive. Results obtained by the modified MBA method revealed that most of the samples were positive for YTX, with the exception of samples from Lim Bay (LB 1) The ELISA method also identified the presence of YTX in these samples. DSP toxin profiles showed the presence of okadaic acid (OA) in three, and YTX in four out of nine samples that were analyzed by LC-MS/MS. The phytoplankton community structure pattern revealed Lingulodinium polyedrum (Stein) Dodge, which was present in the water prior to and/or during toxicity events at low concentrations (80 to 1440 cells L-1), as a potential YTX producing species. It is proposed that L. polyedrum cells accumulated in mussels and the subsequently observed toxicity may be related to metabolism after ingestion, resulting in carboxy YTX as the major analog in the mussel. Full article
(This article belongs to the Special Issue Algal Toxins)

Review

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Open AccessReview Toxin Levels and Profiles in Microalgae from the North-Western Adriatic Sea—15 Years of Studies on Cultured Species
Mar. Drugs 2012, 10(1), 140-162; doi:10.3390/md10010140
Received: 15 November 2011 / Revised: 29 December 2011 / Accepted: 5 January 2012 / Published: 17 January 2012
Cited by 26 | PDF Full-text (654 KB) | HTML Full-text | XML Full-text
Abstract
The Northern Adriatic Sea is the area of the Mediterranean Sea where eutrophication and episodes related to harmful algae have occurred most frequently since the 1970s. In this area, which is highly exploited for mollusk farming, the first occurrence of human intoxication [...] Read more.
The Northern Adriatic Sea is the area of the Mediterranean Sea where eutrophication and episodes related to harmful algae have occurred most frequently since the 1970s. In this area, which is highly exploited for mollusk farming, the first occurrence of human intoxication due to shellfish consumption occurred in 1989, nearly 10 years later than other countries in Europe and worldwide that had faced similar problems. Until 1997, Adriatic mollusks had been found to be contaminated mostly by diarrhetic shellfish poisoning toxins (i.e., okadaic acid and dinophysistoxins) that, along with paralytic shellfish poisoning toxins (i.e., saxitoxins), constitute the most common marine biotoxins. Only once, in 1994, a toxic outbreak was related to the occurrence of paralytic shellfish poisoning toxins in the Adriatic coastal waters. Moreover, in the past 15 years, the Adriatic Sea has been characterized by the presence of toxic or potentially toxic algae, not highly widespread outside Europe, such as species producing yessotoxins (i.e., Protoceratium reticulatum, Gonyaulax spinifera and Lingulodinium polyedrum), recurrent blooms of the potentially ichthyotoxic species Fibrocapsa japonica and, recently, by blooms of palytoxin-like producing species of the Ostreopsis genus. This review is aimed at integrating monitoring data on toxin spectra and levels in mussels farmed along the coast of the Emilia-Romagna region with laboratory studies performed on the species involved in the production of those toxins; toxicity studies on toxic or potentially toxic species that have recently appeared in this area are also reviewed. Overall, reviewed data are related to: (i) the yessotoxins producing species P. reticulatum, G. spinifera and L. polyedrum, highlighting genetic and toxic characteristics; (ii) Adriatic strains of Alexandrium minutum, Alexandrium ostenfeldii and Prorocentrum lima whose toxic profiles are compared with those of strains of different geographic origins; (iii) F. japonica and Ostreopsis cf. ovata toxicity. Moreover, new data concerning domoic acid production by a Pseudo-nitzschia multistriata strain, toxicity investigations on a Prorocentrum cf. levis, and on presumably ichthyotoxic species, Heterosigma akashiwo and Chattonella cf. subsalsa, are also reported. Full article
(This article belongs to the Special Issue Algal Toxins)
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Open AccessReview Cyanotoxins: Bioaccumulation and Effects on Aquatic Animals
Mar. Drugs 2011, 9(12), 2729-2772; doi:10.3390/md9122729
Received: 18 October 2011 / Revised: 29 November 2011 / Accepted: 1 December 2011 / Published: 16 December 2011
Cited by 68 | PDF Full-text (393 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyanobacteria are photosynthetic prokaryotes with wide geographic distribution that can produce secondary metabolites named cyanotoxins. These toxins can be classified into three main types according to their mechanism of action in vertebrates: hepatotoxins, dermatotoxins and neurotoxins. Many studies on the effects of [...] Read more.
Cyanobacteria are photosynthetic prokaryotes with wide geographic distribution that can produce secondary metabolites named cyanotoxins. These toxins can be classified into three main types according to their mechanism of action in vertebrates: hepatotoxins, dermatotoxins and neurotoxins. Many studies on the effects of cyanobacteria and their toxins over a wide range of aquatic organisms, including invertebrates and vertebrates, have reported acute effects (e.g., reduction in survivorship, feeding inhibition, paralysis), chronic effects (e.g., reduction in growth and fecundity), biochemical alterations (e.g., activity of phosphatases, GST, AChE, proteases), and behavioral alterations. Research has also focused on the potential for bioaccumulation and transferring of these toxins through the food chain. Although the herbivorous zooplankton is hypothesized as the main target of cyanotoxins, there is not unquestionable evidence of the deleterious effects of cyanobacteria and their toxins on these organisms. Also, the low toxin burden in secondary consumers points towards biodilution of microcystins in the food web as the predominant process. In this broad review we discuss important issues on bioaccumulation and the effects of cyanotoxins, with emphasis on microcystins, as well as drawbacks and future needs in this field of research. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessReview New Peptides Isolated from Lyngbya Species: A Review
Mar. Drugs 2010, 8(6), 1817-1837; doi:10.3390/md8061817
Received: 13 April 2010 / Revised: 19 May 2010 / Accepted: 3 June 2010 / Published: 9 June 2010
Cited by 35 | PDF Full-text (293 KB) | HTML Full-text | XML Full-text
Abstract
Cyanobacteria of the genusLyngbya have proven to be prodigious producers of secondary metabolites. Many of these compounds are bioactive and show potential for therapeutic use. This review covers peptides and hybrid polyketide-non-ribosomal peptides isolated from Lyngbya species. The structures and bioactivities [...] Read more.
Cyanobacteria of the genusLyngbya have proven to be prodigious producers of secondary metabolites. Many of these compounds are bioactive and show potential for therapeutic use. This review covers peptides and hybrid polyketide-non-ribosomal peptides isolated from Lyngbya species. The structures and bioactivities of 50 Lyngbya peptides which were reported since 2007 are presented. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessReview On the Chemistry, Toxicology and Genetics of the Cyanobacterial Toxins, Microcystin, Nodularin, Saxitoxin and Cylindrospermopsin
Mar. Drugs 2010, 8(5), 1650-1680; doi:10.3390/md8051650
Received: 26 March 2010 / Revised: 2 May 2010 / Accepted: 6 May 2010 / Published: 10 May 2010
Cited by 170 | PDF Full-text (684 KB) | HTML Full-text | XML Full-text
Abstract
The cyanobacteria or “blue-green algae”, as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity. Many aquatic, bloom-forming species of cyanobacteria are capable of [...] Read more.
The cyanobacteria or “blue-green algae”, as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity. Many aquatic, bloom-forming species of cyanobacteria are capable of producing biologically active secondary metabolites, which are highly toxic to humans and other animals. From a toxicological viewpoint, the cyanotoxins span four major classes: the neurotoxins, hepatotoxins, cytotoxins, and dermatoxins (irritant toxins). However, structurally they are quite diverse. Over the past decade, the biosynthesis pathways of the four major cyanotoxins: microcystin, nodularin, saxitoxin and cylindrospermopsin, have been genetically and biochemically elucidated. This review provides an overview of these biosynthesis pathways and additionally summarizes the chemistry and toxicology of these remarkable secondary metabolites. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessReview Prymnesins: Toxic Metabolites of the Golden Alga, Prymnesium parvum Carter (Haptophyta)
Mar. Drugs 2010, 8(3), 678-704; doi:10.3390/md8030678
Received: 6 January 2010 / Revised: 9 March 2010 / Accepted: 10 March 2010 / Published: 16 March 2010
Cited by 28 | PDF Full-text (309 KB) | HTML Full-text | XML Full-text
Abstract
Increasingly over the past century, seasonal fish kills associated with toxic blooms of Prymnesium parvum have devastated aquaculture and native fish, shellfish, and mollusk populations worldwide. Protracted blooms of P. parvum can result in major disturbances to the local ecology and extensive [...] Read more.
Increasingly over the past century, seasonal fish kills associated with toxic blooms of Prymnesium parvum have devastated aquaculture and native fish, shellfish, and mollusk populations worldwide. Protracted blooms of P. parvum can result in major disturbances to the local ecology and extensive monetary losses. Toxicity of this alga is attributed to a collection of compounds known as prymnesins, which exhibit potent cytotoxic, hemolytic, neurotoxic and ichthyotoxic effects. These secondary metabolites are especially damaging to gill-breathing organisms and they are believed to interact directly with plasma membranes, compromising integrity by permitting ion leakage. Several factors appear to function in the activation and potency of prymnesins including salinity, pH, ion availability, and growth phase. Prymnesins may function as defense compounds to prevent herbivory and some investigations suggest that they have allelopathic roles. Since the last extensive review was published, two prymnesins have been chemically characterized and ongoing investigations are aimed at the purification and analysis of numerous other toxic metabolites from this alga. More information is needed to unravel the mechanisms of prymnesin synthesis and the significance of these metabolites. Such work should greatly improve our limited understanding of the physiology and biochemistry of P. parvum and how to mitigate its blooms. Full article
(This article belongs to the Special Issue Algal Toxins)
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Open AccessReview Cyanobacterial Cyclopeptides as Lead Compounds to Novel Targeted Cancer Drugs
Mar. Drugs 2010, 8(3), 629-657; doi:10.3390/md8030629
Received: 4 January 2010 / Revised: 10 February 2010 / Accepted: 26 February 2010 / Published: 15 March 2010
Cited by 32 | PDF Full-text (583 KB) | HTML Full-text | XML Full-text
Abstract
Cyanobacterial cyclopeptides, including microcystins and nodularins, are considered a health hazard to humans due to the possible toxic effects of high consumption. From a pharmacological standpoint, microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cellular damage following uptake via [...] Read more.
Cyanobacterial cyclopeptides, including microcystins and nodularins, are considered a health hazard to humans due to the possible toxic effects of high consumption. From a pharmacological standpoint, microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cellular damage following uptake via organic anion-transporting polypeptides (OATP). Their intracellular biological effects involve inhibition of catalytic subunits of protein phosphatase 1 (PP1) and PP2, glutathione depletion and generation of reactive oxygen species (ROS). Interestingly, certain OATPs are prominently expressed in cancers as compared to normal tissues, qualifying MC as potential candidates for cancer drug development. In the era of targeted cancer therapy, cyanotoxins comprise a rich source of natural cytotoxic compounds with a potential to target cancers expressing specific uptake transporters. Moreover, their structure offers opportunities for combinatorial engineering to enhance the therapeutic index and resolve organ-specific toxicity issues. In this article, we revisit cyanobacterial cyclopeptides as potential novel targets for anticancer drugs by summarizing existing biomedical evidence, presenting structure-activity data and discussing developmental perspectives. Full article
(This article belongs to the Special Issue Algal Toxins)
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Open AccessReview Cylindrospermopsin: A Decade of Progress on Bioaccumulation Research
Mar. Drugs 2010, 8(3), 542-564; doi:10.3390/md8030542
Received: 9 February 2010 / Revised: 3 March 2010 / Accepted: 8 March 2010 / Published: 9 March 2010
Cited by 75 | PDF Full-text (241 KB) | HTML Full-text | XML Full-text
Abstract
Cylindrospermopsin (CYN) is rapidly being recognised as one of the most globally important of the freshwater algal toxins. The ever-expanding distribution of CYN producers into temperate zones is heightening concern that this toxin will represent serious human, as well as environmental, health [...] Read more.
Cylindrospermopsin (CYN) is rapidly being recognised as one of the most globally important of the freshwater algal toxins. The ever-expanding distribution of CYN producers into temperate zones is heightening concern that this toxin will represent serious human, as well as environmental, health risks across many countries. Since 1999, a number of studies have demonstrated the ability for CYN to bioaccumulate in freshwater organisms. This paper synthesizes the most current information on CYN accumulation, including notes on the global distribution of CYN producers, and a précis of CYN’s ecological and human effects. Studies on the bioaccumulation of CYN are systematically reviewed, together with an analysis of patterns of accumulation. A discussion on the factors influencing bioaccumulation rates and potential is also provided, along with notes on detection, monitoring and risk assessments. Finally, key gaps in the existing research are identified for future study. Full article
(This article belongs to the Special Issue Algal Toxins)

Other

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Open AccessCase Report An Acute Case of Intoxication with Cyanobacteria and Cyanotoxins in Recreational Water in Salto Grande Dam, Argentina
Mar. Drugs 2011, 9(11), 2164-2175; doi:10.3390/md9112164
Received: 7 September 2011 / Revised: 19 October 2011 / Accepted: 20 October 2011 / Published: 31 October 2011
Cited by 30 | PDF Full-text (261 KB) | HTML Full-text | XML Full-text
Abstract
Cyanobacterial blooms and hepatotoxic microcystins (MCs) usually occur in summer, constituting a sanitary and environmental problem in Salto Grande Dam, Argentina. Water sports and recreational activities take place in summer in this lake. We reported an acute case of cyanobacterial poisoning in [...] Read more.
Cyanobacterial blooms and hepatotoxic microcystins (MCs) usually occur in summer, constituting a sanitary and environmental problem in Salto Grande Dam, Argentina. Water sports and recreational activities take place in summer in this lake. We reported an acute case of cyanobacterial poisoning in Salto Grande dam, Argentina, which occurred in January 2007. Accidentally, a young man was immersed in an intense bloom of Microcystis spp. A level of 48.6 µg·L−1 of microcystin-LR was detected in water samples. Four hours after exposure, the patient showed nausea, abdominal pain and fever. Three days later, dyspnea and respiratory distress were reported. The patient was hospitalized in intensive care and diagnosed with an atypical pneumonia. Finally, a week after the exposure, the patient developed a hepatotoxicosis with a significant increase of hepatic damage biomarkers (ALT, AST and γGT). Complete recovery took place within 20 days. This is the first study to show an acute intoxication with microcystin-producing cyanobacteria blooms in recreational water. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessEssay The Relevance of Marine Chemical Ecology to Plankton and Ecosystem Function: An Emerging Field
Mar. Drugs 2011, 9(9), 1625-1648; doi:10.3390/md9091625
Received: 27 July 2011 / Revised: 5 September 2011 / Accepted: 9 September 2011 / Published: 22 September 2011
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Abstract
Marine chemical ecology comprises the study of the production and interaction of bioactive molecules affecting organism behavior and function. Here we focus on bioactive compounds and interactions associated with phytoplankton, particularly bloom-forming diatoms, prymnesiophytes and dinoflagellates. Planktonic bioactive metabolites are structurally and [...] Read more.
Marine chemical ecology comprises the study of the production and interaction of bioactive molecules affecting organism behavior and function. Here we focus on bioactive compounds and interactions associated with phytoplankton, particularly bloom-forming diatoms, prymnesiophytes and dinoflagellates. Planktonic bioactive metabolites are structurally and functionally diverse and some may have multiple simultaneous functions including roles in chemical defense (antipredator, allelopathic and antibacterial compounds), and/or cell-to-cell signaling (e.g., polyunsaturated aldehydes (PUAs) of diatoms). Among inducible chemical defenses in response to grazing, there is high species-specific variability in the effects on grazers, ranging from severe physical incapacitation and/or death to no apparent physiological response, depending on predator susceptibility and detoxification capability. Most bioactive compounds are present in very low concentrations, in both the producing organism and the surrounding aqueous medium. Furthermore, bioactivity may be subject to synergistic interactions with other natural and anthropogenic environmental toxicants. Most, if not all phycotoxins are classic secondary metabolites, but many other bioactive metabolites are simple molecules derived from primary metabolism (e.g., PUAs in diatoms, dimethylsulfoniopropionate (DMSP) in prymnesiophytes). Producing cells do not seem to suffer physiological impact due to their synthesis. Functional genome sequence data and gene expression analysis will provide insights into regulatory and metabolic pathways in producer organisms, as well as identification of mechanisms of action in target organisms. Understanding chemical ecological responses to environmental triggers and chemically-mediated species interactions will help define crucial chemical and molecular processes that help maintain biodiversity and ecosystem functionality. Full article
(This article belongs to the Special Issue Algal Toxins)

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