title: Diatom Nitzschia navis-varingica (Bacillariophyceae) and its domoic acid production from the mangrove environments of Malaysia.
abstract: The distribution of the toxic pennate diatom Nitzschia was investigated at four mangrove areas along the coastal brackish waters of Peninsular Malaysia. Eighty-two strains of N. navis-varingica were isolated and established, and their identity confirmed morphologically and molecularly. Frustule morphological characteristics of the strains examined are identical to previously identified N. navis-varingica, but with a sightly higher density of the number of areolae per 1μm (4-7 areolae). Both LSU and ITS rDNAs phylogenetic trees clustered all strains in the N. navis-varingica clade, with high sequence homogeneity in the LSU rDNA (0-0.3%), while the intraspecific divergences in the ITS2 data set reached up to 7.4%. Domoic acid (DA) and its geometrical isomers, isodomoic A (IA) and isodomoic B (IB), were detected in cultures of N. navis-varingica by FMOC-LC-FLD, and subsequently confirmed by LC-MS/MS, with selected ion monitoring (SIM) and multiple reaction monitoring (MRM) runs. DA contents ranged between 0.37 and 11.06pgcell-1. This study demonstrated that the toxigenic euryhaline diatom N. navis-varingica is widely distributed in Malaysian mangrove swamps, suggesting the risk of amnesic shellfish poisoning and the possibility of DA contamination in the mangrove-related fisheries products.
authors.affiliation: Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia.
authors.forename: Suh Nih
authors.initials: SN
authors.lastname: Tan
authors.affiliation: Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia.
authors.forename: Sing Tung
authors.initials: ST
authors.lastname: Teng
authors.affiliation: Tunku Abdul Rahman University College, Johor Branch, 85000 Segamat, Johor, Malaysia.
authors.forename: Hong Chang
authors.initials: HC
authors.lastname: Lim
authors.affiliation: School of Marine Biosciences, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kotaki
authors.affiliation: Fisheries and Oceans Canada, Gulf Fisheries Centre, P. O. Box 5030, Moncton, New Brunswick E1C 9B6, Canada.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Bates
authors.affiliation: Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia. Electronic address: cpleaw@um.edu.my.
authors.forename: Chui Pin
authors.initials: CP
authors.lastname: Leaw
authors.affiliation: Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia. Electronic address: ptlim@um.edu.my.
authors.forename: Po Teen
authors.initials: PT
authors.lastname: Lim
mesh_terms: D000818:Animals; D004275:DNA, Ribosomal / Q000235:genetics; D017377:Diatoms / Q000378:metabolism*; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D008296:Malaysia; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D004275:DNA, Ribosomal; C012301:domoic acid; D007608:Kainic Acid
keywords: Amnesic shellfish poisoning; Brackish water; Domoic acid; ITS2; LSU rDNA; Nitzschia navis-varingica; Phylogeny