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Journal Articles - UP - MSI

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    Characterization of Alexandrium tamutum (Dinophyceae) isolated from Philippine waters, with the rare detection of paralytic shellfish toxin
    Benico, Garry; Azanza, Rhodora (Association of Systematic Biologists of the Philippines, 2022-04-01)
    Alexandrium tamutum M.Montressor, A.Beran & U.John is a non-toxic, bloom-forming dinoflagellate species commonly reported in temperate waters. In this study, 8 cultures of A. tamutum established from Bolinao Channel and Manila Bay, Philippines were characterized in terms of their morphology, phylogeny and toxicity. Cells were roundish, measuring 25.5 –29.84 µm long and 26.2–28.45 µm wide. The nucleus is equatorially elongated and located at the center of the cell. The chloroplasts are numerous, golden brown in color and radially arranged. Thecal tabulation is typical of Alexandrium: APC, 4', 6'', 6c, 6s, 5''', 2''''. Shape of the taxonomically informative thecal plates such as sixth precingular plate (6'') and posterior sulcal plate (sp) was similar to A. tamutum, which confirms the species identity. However, the presence of anterior and posterior attachment pores observed in our cultured isolates is the first case in this species. Molecular phylogeny inferred from LSU rDNA and ITS supports our identification by forming a well-supported clade composed of A. tamutum strains from other geographic regions. HPLC analysis showed that A. tamutum is generally non-toxic except for strain ATC9 which has low amount of decarbamoylsaxitoxin (dcSTX), resulting to a toxicity of 0.07 fmole STX eq per cell. The present study reports the first verified occurrence of Philippine A. tamutum with reliable morphological and molecular information, including the first record in Manila Bay and first detection of PST in one strain at a certain culture period.
    We acknowledge the Department of Science and Technology Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST PCAARRD) and the University of the Philippines-The Marine Science Institute (UP-MSI) for the funding support. We are grateful for the assistance of Joshua Vacarizas, Keith Pinto and Jenelyn Mendoza for the molecular and toxicity analyses of the cultures. We also acknowledge Estrelita Flores, Emelita Eugenio and Jayson Orpeza for their assistance during the fieldwork and other logistical support.
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    Global mass spectrometric analysis reveals chemical diversity of secondary metabolites and 44-Methylgambierone production in Philippine Gambierdiscus strains
    Malto, Zabrina Bernice L.; Benico, Garry A.; Batucan, Jeremiah D.; Dela Cruz, James; Romero, Marc Lawrence J.; Azanza, Rhodora V.; Salvador-Reyes, Lilibeth A. (Frontiers Media SA, 2022-02-04)
    Surveillance and characterization of emerging marine toxins and toxigenic dinoflagellates are warranted to evaluate their associated health risks. Here, we report the occurrence of the ciguatera poisoning-causative dinoflagellate Gambierdiscus balechii in the Philippines. Toxin production and chemical diversity of secondary metabolites in G. balechii GtoxSAM092414, G. balechii Gtox112513, and the recently reported Gambierdiscus carpenteri Gam1BOL080513 were assessed using targeted and untargeted UPLC-MS/MS analysis and radioligand receptor-binding assay (RBA). 44-methylgambierone was produced by all three strains, albeitwith different levels based on RBA and UPLC-HRMS/MS analysis. The fatty acid composition was similar in all strains, while subtle differences in monosaccharide content were observed, related to the collection site rather than the species. Molecular networking using the GNPS database identified 45 clusters belonging to at least ten compound classes, with terpene glycosides, carbohydrate conjugates, polyketides, and macrolides as major convergence points. Species-specific peptides and polyhydroxylated compounds were identified in G. balechii GtoxSAM092414 and G. carpenteri Gam1BOL080513, respectively. These provide a glimpse of the uncharacterized biosynthetic potential of benthic dinoflagellates and highlight the intricate and prolific machinery for secondary metabolites production in these organisms.
    We would like to thank H. Junio and the Secondary Metabolites Profiling Laboratory of the Institute of Chemistry, University of the Philippines Diliman and K. B. Davis for assistance in the conduct of this study.