Does Osmotic Stress Affect Natural Product Expression in Fungi?

Acknowledgments: Russell Kerr acknowledges the assistance of Nadia Prigoda-Lee, Marius Grote, Kate McQuillan and Stephanie Duffy, and generous financial support from NSERC, the Canada Research Chair program, the Jeanne and Jean-Louis Lévesque Foundation and the Atlantic Canada Opportunities Agency. Ka-Lai Pang thanks the president of National Taiwan Ocean University, Ching-Fong Chang, for a special fund to attend the workshop held in Charlottetown, Canada in 2014 where this work was discussed. Rob Capon and Zhuo Shang acknowledge support from the University of Queensland, and the UQ Institute for Molecular Bioscience. Zhuo Shang acknowledges the provision of an International Postgraduate Research Scholarship (IPRS) and a Centennial Scholarship by the University of Queensland. Catherine Roullier acknowledges the assistance of Marie-Claude Boumard and Thibaut Robiou du Pont, and support from Region Pays de la Loire, FrancePeer reviewedPublisher PD

Maitotoxin-4, a Novel MTX Analog Produced by Gambierdiscus excentricus

Maitotoxins (MTXs) are among the most potent toxins known. These toxins are produced by epi-benthic dinoflagellates of the genera Gambierdiscus and Fukuyoa and may play a role in causing the symptoms associated with Ciguatera Fish Poisoning. A recent survey revealed that, of the species tested, the newly described species from the Canary Islands, G. excentricus, is one of the most maitotoxic. The goal of the present study was to characterize MTX-related compounds produced by this species. Initially, lysates of cells from two Canary Island G. excentricus strains VGO791 and VGO792 were partially purified by (i) liquid-liquid partitioning between dichloromethane and aqueous methanol followed by (ii) size-exclusion chromatography. Fractions from chromatographic separation were screened for MTX toxicity using both the neuroblastoma neuro-2a (N2a) cytotoxicity and Ca2+ flux functional assays. Fractions containing MTX activity were analyzed using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) to pinpoint potential MTX analogs. Subsequent non-targeted HRMS analysis permitted the identification of a novel MTX analog, maitotoxin-4 (MTX4, accurate mono-isotopic mass of 3292.4860 Da, as free acid form) in the most toxic fractions. HRMS/MS spectra of MTX4 as well as of MTX are presented. In addition, crude methanolic extracts of five other strains of G. excentricus and 37 other strains representing one Fukuyoa species and ten species, one ribotype and one undetermined strain/species of Gambierdiscus were screened for the presence of MTXs using low resolution tandem mass spectrometry (LRMS/MS). This targeted analysis indicated the original maitotoxin (MTX) was only present in one strain (G. australes S080911_1). Putative maitotoxin-2 (p-MTX2) and maitotoxin-3 (p-MTX3) were identified in several other species, but confirmation was not possible because of the lack of reference material. Maitotoxin-4 was detected in all seven strains of G. excentricus examined, independently of their origin (Brazil, Canary Islands and Caribbean), and not detected in any other species. MTX4 may therefore serve as a biomarker for the highly toxic G. excentricus in the Atlantic area

Recent progress in marine mycological research in different countries, and prospects for future developments worldwide

Early research on marine fungi was mostly descriptive, with an emphasis on their diversity and taxonomy, especially of those collected at rocky shores on seaweeds and driftwood. Subsequently, further substrata (e.g. salt marsh grasses, marine animals, seagrasses, sea foam, seawater, sediment) and habitats (coral reefs, deep-sea, hydrothermal vents, mangroves, sandy beaches, salt marshes) were explored for marine fungi. In parallel, research areas have broadened from micro-morphology to ultrastructure, ecophysiology, molecular phylogenetics, biogeography, biodeterioration, biodegradation, bioprospecting, genomics, proteomics, transcriptomics and metabolomics. Although marine fungi only constitute a small fraction of the global mycota, new species of marine fungi continue to be described from new hosts/substrata of unexplored locations/habitats, and novel bioactive metabolites have been discovered in the last two decades, warranting a greater collaborative research effort. Marine fungi of Africa, the Americas and Australasia are under-explored, while marine Chytridiomycota and allied taxa, fungi associated with marine animals, the functional roles of fungi in the sea, and the impacts of climate change on marine fungi are some of the topics needing more attention. In this article, currently active marine mycologists from different countries have written on the history and current state of marine fungal research in individual countries highlighting their strength in the subject, and this represents a first step towards a collaborative inter- and transdisciplinary research strategy

Time Dependency of Chemodiversity and Biosynthetic Pathways: An LC-MS Metabolomic Study of Marine-Sourced Penicillium

This work aimed at studying metabolome variations of marine fungal strains along their growth to highlight the importance of the parameter “time” for new natural products discovery. An untargeted time-scale metabolomic study has been performed on two different marine-derived Penicillium strains. They were cultivated for 18 days and their crude extracts were analyzed by HPLC-DAD-HRMS (High Performance Liquid Chromatography-Diode Array Detector-High Resolution Mass Spectrometry) each day. With the example of griseofulvin biosynthesis, a pathway shared by both strains, this work provides a new approach to study biosynthetic pathway regulations, which could be applied to other metabolites and more particularly new ones. Moreover, the results of this study emphasize the interest of such an approach for the discovery of new chemical entities. In particular, at every harvesting time, previously undetected features were observed in the LC-MS (Liquid Chromatography-Mass Spectrometry) data. Therefore, harvesting times for metabolite extraction should be performed at different time points to access the hidden metabolome

Recherche de mycosporines et de dérivés aminés lichéniques d intérêt pour les cancers photoinduits (étude phytochimique d un lichen marin)

Suite à l augmentation croissante des cancers de la peau, la recherche de nouvelles solutions thérapeutiques (et préventives) est nécessaire. Les lichens sont une source prometteuse de métabolites secondaires. Dans un premier temps, un criblage de différents lichens à cyanobactéries a permis de mettre en évidence la présence de composés de type mycosporine dans plusieurs d entre elles et notamment d une structure nouvellement décrite. La mycosporine sérinol a pu ensuite être isolée en quantité à partir d un lichen marin Lichina pygmaea. Son étude phytochimique plus poussée a conduit à l isolement de nouveaux dérivés aminés, comme la pygméine dont l accès à des analogues de synthèse a permis de confirmer son identification. La plupart des composés obtenus en quantité suffisante ont été évalués pour leurs capacités photoprotectrice et à visée anticancéreuse. Quelques composés ont montré une activité intéressante et pourraient être de bons candidats dans la protection des cancers photoinduits.As cutaneous cancers are increasing, research of new therapeutic solutions is necessary and the lichens are a promising source of secondary metabolites. Initially, a screening of various lichens containing cyanobacteria has highlighted the presence of mycosporine-like compounds in several of them, including a newly described structure. Then, mycosporine serinol has been isolated quantitatively from a marine lichen Lichina pygmaea. Further phytochemical studies led to the isolation of new amino derivatives, like pygmeine which has been synthetized along with analogues. Most of the compounds obtained in suitable quantity were evaluated for their photoprotective properties and in anti-cancer targeted tests. Some compounds showed interesting activity and could be good candidates in the protection of photoinduced skin cancers.RENNES1-BU Sciences Philo (352382102) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Potentiel anticancéreux de la combrétastatine A-4 et de dérivés (exemple de l'accès à des dérivés flavoniques)

LYON1-BU Santé (693882101) / SudocRENNES1-BU Santé (352382103) / SudocSudocFranceF

Mycosporine-Like Amino Acids (MAAs) in Biological Photosystems

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Synthesis and anti-tubulin evaluation of chromone-based analogues of combretastatins

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ChromAnnot a webserver for deep LC-HRMS/MS chromatogram annotation

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Multiple dual-mode centrifugal partition chromatography as an efficient method for the purification of a mycosporine from a crude methanolic extract of Lichina pygmaea

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