Special Issue "Algal Toxins"

Guest Editor
Prof. Dr. John P. Berry
Department of Chemistry and Biochemistry, 354 Marine Science Building, Florida International University, 3000 NE 151st Street, North Miami, FL 33181, USA
Website: http://www.fiu.edu/~berryj/
E-Mail:
Interests: cyanobacteria; toxins; bioactive compounds; zebrafish embryo model; natural products

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

Related Special Issues in other Journals:

Algal Toxins in Toxins

Submission

All papers should be submitted to marinedrugs@mdpi.org with copy to the Editors. To be published continuously until the deadline and papers will be listed together at the special websites. Both, research articles and review articles are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editors for announcment on this website.

Submitted papers should not have been published previously, nor be under consideration for publication elsewhere. All papers are refereed through a peer-review process. A guide for authors, sample copies and other relevant information for submitting papers are available on the Instructions for Authors page. Marine Drugs is an international peer-reviewed quarterly journal published by Molecular Diversity Preservation International.

Please visit the Instructions for Authors page before submitting a paper Open Access publication fees are 1000 CHF per paper. English correction fees (250 CHF) will be added in certain cases (1250 CHF per paper for those papers that require extensive additional formatting and/or English corrections.).

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

Type of Paper: Review
Titel: Cyanobacterial Cyclopeptides as Leads to Novel Targeted Cancer Drugs
Authors: Ioannis Sainis¹, Dimosthenis Fokas², Katerina Vareli³, Andreas Tzakos^1,4, Valentinos Kounnis^1,5, Evangelos Briasoulis^1,5
Affiliations: ¹ Human Cancer Biobank Center, Molecular Oncology Lab, University of Ioannina, Greece
² Department of Materials Science and Engineering, University of Ioannina, Greece
³ Department of Biological Applications and Technologies, University of Ioannina, Greece
⁴ Department of Chemistry, University of Ioannina, Greece
⁵ School of Medicine, University of Ioannina, Greece
Abstract: Cyanobacterial cyclopeptides microcystins and nodularins are considered a health hazard to humans due to possible toxic effects upon high consumption. From pharmacological standpoint microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cell damage following cellular uptake via organic anion-transporting proteins (OATP). Their intracellular biologic effects presumably involve inhibition of catalytic subunits of protein phosphatase 1 (PP1) and PP2 and glutathione depletion. Interestingly, OATPs are prominently expressed in cancers as compared to normal tissues, which makes microcystins qualify as potential lead candidates for cancer drug development. Today 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 leads to novel targeted anticancer drugs by summarizing existing biomedical evidence, presenting structure-activity data and discussing developmental perspectives.

Type of Paper: Review
Title: Bioaccumulation of Cyanotoxins and Their Effects on Aquatic Organisms
Author: Aloysio da Silva Ferrão Filho
Affiliation: Laboratório de Avaliação e Promoção da Saúde Ambiental – Instituto Oswaldo Cruz – FIOCRUZ, Av. Brasil 4365, Manguinhos, CEP 21045-900, Rio de Janeiro, RJ, Brasil; E-Mail: aloysio@ioc.fiocruz.br
Abstract: Cyanobacteria are photosynthetic procariotes with wide geographic distribution, occurring in many different ecosystems. They produce secondary metabolites named cyanotoxins, which can be classified in three main types: hepatotoxins, dermatotoxins and neurotoxins. Many studies showed the effects of cynobacteria and their toxins over a wide range of aquatic organisms, including invertebrates and vertebrates. These include acute effects (reduction in survivorship, feeding inhibition, paralysis) and chronic effects (e.g. reduction in growth and fecundity). Some studies also reported biochemical alterations, (e.g. on the activity of phosphatases, GST, AChE, and proteases) and behavioral alterations. As the main target of cyanotoxins seems to be the herbivorous zooplankton, research efforts have focused on this link, showing indeed its potential for bioaccumulation and transferring of these toxins through the food chain. However, the large variability found in results of many studies has lead to equivocal conclusions. Although there is unequivocal evidence of deleterious effects of cyanobacteria and their toxins, the resistance of some zooplankton species and the absence of effect of microcystins on Daphnia in some studies raised the question whether this toxin would be serving as a chemical defense mechanism against zooplankton grazing. The present manuscript presents a broad review of studies about bioaccumulation and the effects of cyanotoxins, especially on freshwater organisms.

Type of Paper: Review
Title: Prymnesins: Ichthyotoxic Polyketides of The Golden Alga, Prymnesium parvum Carter (Haptophyta)
Authors: Schonna R. Manning and John W. La Claire II
Affiliation: MCD Biology (A6700), University of Texas at Austin, TX 78712, USA; E-Mail: laclaire@uts.cc.utexas.edu
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 around the globe. These blooms result in major disturbances to the local ecology as well as extensive monetary losses. P. parvum is known to synthesize numerous harmful secondary metabolites, including the complex polyketides, prymnesin-1 and prymnesin-2. Prymnesins are classified as polycyclic ethers with amphipathic characteristics that have potent cytotoxic, hemolytic, neurotoxic and ichthyotoxic effects. These compounds have been found to be especially damaging to gill tissues where it is believed they interact with plasma membranes by compromising membrane integrity and permitting ion leakage. Several environmental factors appear to play a role in the activation and potency of prymnesins including salinity, pH, temperature and specific ion availability. Like many secondary metabolites, prymnesins have been proposed to function as defense compounds for preventing herbivory, but some investigations suggest that they may have allelopathic roles. Ongoing investigations are aimed at further elucidation of prymnesins’ chemical structures, their biosynthesis and their functions. Such work should greatly improve our limited understanding of the basic biology of P. parvum and how its toxic blooms might be mitigated.

Type of Paper: Review
Title: Biological Methods of Cyanotoxins Elimination: An Overview
Authors: Dariusz Dziga and Marcin Wasylewski
Affiliation: Jagiellonian University, Faculty of Biochemistry, Biophysics and Biotechnology, Department of Plant Physiology and Development, Gronostajowa 7, PL-30387 Kraków, Poland; E-Mail: dariusz.dziga@uj.edu.pl
Abstract: Several species of marine and freshwater cyanobacteria produce different toxic compounds e.g. hepatotoxins, neurotoxins and cytotoxins that constitute a significant problem all over the world. Besides the chemical and physical methods of their decomposition some mechanisms of bio-elimination are investigated. In this review the broad spectrum of research that focuses on biological methods of neutralization of toxins produced by cyanobacteria is presented - involving especially enzymatic degradation in the presence of different bacterial strains, bioaccumulation and detoxication using aquatic macrophytes. Some interesting proposal of the application of such biological methods that would constitute an alternative procedure for cyanobacterial toxin removal from drinking water or smaller water reservoir have also been discussed.