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Special Issue "Marine Dinoflagellates"

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

Deadline for manuscript submissions: closed (30 June 2014)

Special Issue Editor

Guest Editor
Dr. Andrea Bourdelais

Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington NC, 28409, USA
Phone: 910-962-2365
Fax: +1 910 962 2410
Interests: isolation and structure elucidation of bioactive marine natural products; polyether compounds; bioassay screening; high content screening; quantitative analysis of marine toxins; harmful algal blooms; Florida red tide; marine dinoflagellates

Special Issue Information

Dear Colleagues,

Dinoflagellates comprise a diverse class of flagellated protists found in marine and fresh water environments. Of the approximately 2000 living species about 1700 species are found in marine environments. Due to the complex nature of the marine environment these microorganisms have developed unique biosynthetic machinery for the production of metabolites with unusual chemical structures and potent biological activities. Naturally produced chemical families include polyethers, macrolides, polyhydroxy compounds, heterocycles, polyketals, amino acids, terpenes, phytopigments, and purine derivatives. Although metabolites produced by these micro-organisms are known for their cytotoxicity, many have show selective activity in biological systems for example: saxitoxins are selective sodium channel blockers, brevetoxins and ciguatoxins selectively activate sodium channels, and maitotoxins act on calcium channels. Other metabolites have been found to inhibit enzymes (okadaic acid), yet others have show potent activity as anti-fungal (gamberic acids) or anti-tumor (amphidinols) agents. Because of their unprecedented biosynthetic capabilities and ease of culture, dinoflagellates provide a renewable source for novel chemical structures that may be used as biological tools or drug candidates. This special issue will be devoted to the bioactivity of both natural and chemically modified dinoflagellate metabolites as well the biosynthetic pathways involved in their production.

Dr. Andrea J. Bourdelais
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Marine Drugs is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).


Keywords

  • marine natural products
  • bioactive metabolites
  • microalgae
  • mechanism of action
  • therapeutic potential
  • polyethers
  • phytopigments
  • lipids
  • marine toxins
  • bioassays
  • culturing
  • bioactive compounds
  • symbiotic relationships
  • natural defenses
  • biosynthesis
  • semisynthetic derivatives
  • bioactivity
  • structure activity relationships
  • environmental impact

Published Papers (5 papers)

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Research

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Open AccessArticle SxtA and sxtG Gene Expression and Toxin Production in the Mediterranean Alexandrium minutum (Dinophyceae)
Mar. Drugs 2014, 12(10), 5258-5276; doi:10.3390/md12105258
Received: 23 July 2014 / Revised: 23 September 2014 / Accepted: 15 October 2014 / Published: 22 October 2014
Cited by 7 | PDF Full-text (409 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The dinoflagellate Alexandrium minutum is known for the production of potent neurotoxins affecting the health of human seafood consumers via paralytic shellfish poisoning (PSP). The aim of this study was to investigate the relationship between the toxin content and the expression level [...] Read more.
The dinoflagellate Alexandrium minutum is known for the production of potent neurotoxins affecting the health of human seafood consumers via paralytic shellfish poisoning (PSP). The aim of this study was to investigate the relationship between the toxin content and the expression level of the genes involved in paralytic shellfish toxin (PST) production. The algal cultures were grown both in standard f/2 medium and in phosphorus/nitrogen limitation. In our study, LC-HRMS analyses of PST profile and content in different Mediterranean A. minutum strains confirmed that this species was able to synthesize mainly the saxitoxin analogues Gonyautoxin-1 (GTX1) and Gonyautoxin-4 (GTX4). The average cellular toxin content varied among different strains, and between growth phases, highlighting a decreasing trend from exponential to stationary phase in all culture conditions tested. The absolute quantities of intracellular sxtA1 and sxtG mRNA were not correlated with the amount of intracellular toxins in the analysed A. minutum suggesting that the production of toxins may be regulated by post-transcriptional mechanisms and/or by the concerted actions of alternative genes belonging to the PST biosynthesis gene cluster. Therefore, it is likely that the sxtA1 and sxtG gene expression could not reflect the PST accumulation in the Mediterranean A. minutum populations under the examined standard and nutrient limiting conditions. Full article
(This article belongs to the Special Issue Marine Dinoflagellates)
Open AccessArticle A New Cytotoxicity Assay for Brevetoxins Using Fluorescence Microscopy
Mar. Drugs 2014, 12(9), 4868-4882; doi:10.3390/md12094868
Received: 1 August 2014 / Revised: 1 September 2014 / Accepted: 4 September 2014 / Published: 23 September 2014
Cited by 2 | PDF Full-text (1080 KB) | HTML Full-text | XML Full-text
Abstract
Brevetoxins are a family of ladder-framed polyether toxins produced during blooms of the marine dinoflagellate, Karenia brevis. Consumption of shellfish or finfish exposed to brevetoxins can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are believed [...] Read more.
Brevetoxins are a family of ladder-framed polyether toxins produced during blooms of the marine dinoflagellate, Karenia brevis. Consumption of shellfish or finfish exposed to brevetoxins can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are believed to be due to the activation of voltage-sensitive sodium channels in cell membranes. The traditional cytotoxicity assay for detection of brevetoxins uses the Neuro-2A cell line, which must first be treated with the neurotoxins, ouabain and veratridine, in order to become sensitive to brevetoxins. In this study, we demonstrate several drawbacks of the Neuro-2A assay, which include variability for the EC50 values for brevetoxin and non-linear triphasic dose response curves. Ouabain/ veratridine-treated Neuro-2A cells do not show a typical sigmoidal dose response curve in response to brevetoxin, but rather, have a polynomial shaped curve, which makes calculating EC50 values highly variable. We describe a new fluorescence live cell imaging model, which allows for accurate calculation of cytotoxicity via nuclear staining and additional measurement of other viability parameters depending on which aspect of the cell is stained. In addition, the SJCRH30 cell line shows promise as an alternative to Neuro-2A cells for testing brevetoxins without the need for ouabain and veratridine. Full article
(This article belongs to the Special Issue Marine Dinoflagellates)
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Open AccessArticle Obtaining Spheroplasts of Armored Dinoflagellates and First Single-Channel Recordings of Their Ion Channels Using Patch-Clamping
Mar. Drugs 2014, 12(9), 4743-4755; doi:10.3390/md12094743
Received: 1 July 2014 / Revised: 18 August 2014 / Accepted: 26 August 2014 / Published: 5 September 2014
Cited by 2 | PDF Full-text (849 KB) | HTML Full-text | XML Full-text
Abstract
Ion channels are tightly involved in various aspects of cell physiology, including cell signaling, proliferation, motility, endo- and exo-cytosis. They may be involved in toxin production and release by marine dinoflagellates, as well as harmful algal bloom proliferation. So far, the patch-clamp [...] Read more.
Ion channels are tightly involved in various aspects of cell physiology, including cell signaling, proliferation, motility, endo- and exo-cytosis. They may be involved in toxin production and release by marine dinoflagellates, as well as harmful algal bloom proliferation. So far, the patch-clamp technique, which is the most powerful method to study the activity of ion channels, has not been applied to dinoflagellate cells, due to their complex cellulose-containing cell coverings. In this paper, we describe a new approach to overcome this problem, based on the preparation of spheroplasts from armored bloom-forming dinoflagellate Prorocentrum minimum. We treated the cells of P. minimum with a cellulose synthesis inhibitor, 2,6-dichlorobenzonitrile (DCB), and found out that it could also induce ecdysis and arrest cell shape maintenance in these microalgae. Treatment with 100–250 µM DCB led to an acceptable 10% yield of P. minimum spheroplasts and was independent of the incubation time in the range of 1–5 days. We show that such spheroplasts are suitable for patch-clamping in the cell-attached mode and can form 1–10 GOhm patch contact with a glass micropipette, allowing recording of ion channel activity. The first single-channel recordings of dinoflagellate ion channels are presented. Full article
(This article belongs to the Special Issue Marine Dinoflagellates)
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Review

Jump to: Research

Open AccessReview Biosynthesis and Molecular Genetics of Polyketides in Marine Dinoflagellates
Mar. Drugs 2010, 8(4), 1011-1048; doi:10.3390/md8041011
Received: 24 February 2010 / Revised: 17 March 2010 / Accepted: 26 March 2010 / Published: 31 March 2010
Cited by 42 | PDF Full-text (423 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Marine dinoflagellates are the single most important group of algae that produce toxins, which have a global impact on human activities. The toxins are chemically diverse, and include macrolides, cyclic polyethers, spirolides and purine alkaloids. Whereas there is a multitude of studies [...] Read more.
Marine dinoflagellates are the single most important group of algae that produce toxins, which have a global impact on human activities. The toxins are chemically diverse, and include macrolides, cyclic polyethers, spirolides and purine alkaloids. Whereas there is a multitude of studies describing the pharmacology of these toxins, there is limited or no knowledge regarding the biochemistry and molecular genetics involved in their biosynthesis. Recently, however, exciting advances have been made. Expressed sequence tag sequencing studies have revealed important insights into the transcriptomes of dinoflagellates, whereas other studies have implicated polyketide synthase genes in the biosynthesis of cyclic polyether toxins, and the molecular genetic basis for the biosynthesis of paralytic shellfish toxins has been elucidated in cyanobacteria. This review summarises the recent progress that has been made regarding the unusual genomes of dinoflagellates, the biosynthesis and molecular genetics of dinoflagellate toxins. In addition, the evolution of these metabolic pathways will be discussed, and an outlook for future research and possible applications is provided. Full article
(This article belongs to the Special Issue Marine Dinoflagellates)
Open AccessReview Synthesis of Marine Polycyclic Polyethers via Endo-Selective Epoxide-Opening Cascades
Mar. Drugs 2010, 8(3), 763-809; doi:10.3390/md8030763
Received: 25 February 2010 / Revised: 11 March 2010 / Accepted: 18 March 2010 / Published: 19 March 2010
Cited by 26 | PDF Full-text (3185 KB) | HTML Full-text | XML Full-text
Abstract
The proposed biosynthetic pathways to ladder polyethers of polyketide origin and oxasqualenoids of terpenoid origin share a dramatic epoxide-opening cascade as a key step. Polycyclic structures generated in these biosynthetic pathways display biological effects ranging from potentially therapeutic properties to extreme lethality. [...] Read more.
The proposed biosynthetic pathways to ladder polyethers of polyketide origin and oxasqualenoids of terpenoid origin share a dramatic epoxide-opening cascade as a key step. Polycyclic structures generated in these biosynthetic pathways display biological effects ranging from potentially therapeutic properties to extreme lethality. Much of the structural complexity of ladder polyether and oxasqualenoid natural products can be traced to these hypothesized cascades. In this review we summarize how such epoxide-opening cascade reactions have been used in the synthesis of ladder polyethers and oxasqualenoid natural products. Full article
(This article belongs to the Special Issue Marine Dinoflagellates)
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