Discrimination of the toxigenic dinoflagellates Alexandrium tamarense and A. ostenfeldii in co-occurring natural populations from Scottish coastal waters

By U. John, A. Cembella, C. Hummert, M. Elbrächter, R. Groben, Linda K. Medlin. 2003

142 citations recorded by the source corpus.

Blooms of the toxic dinoflagellate Alexandrium tamarense (Lebour) Balech, a known producer of potent neurotoxins associated with paralytic shellfish poisoning (PSP), are common annual events along the Scottish east coast. The cooccurrence of a second Alexandrium species, A. ostenfeldii (Paulsen) Balech & Tangen is reported in this study from waters of the Scottish east coast. The latter species has been suspected to be an alternative source of PSP toxins in northern Europe. Recent identification of toxic macrocyclic imines known as spirolides in A. ostenfeldii indicates a potential new challenge for monitoring toxic Alexandrium species and their respective toxins in natural populations. In mixed Phytoplankton assemblages, Alexandrium species are difficult to discriminate accurately by conventional light microscopy. Species-specific rRNA probes based upon 18S and 28S ribosomal DNA sequences were developed for A. ostenfeldii and tested by dot-blot and fluorescence in situ hybridization (FISH) techniques. Hybridization patterns of A. ostenfeldii probes for cultured Alexandrium isolates, and cells from field populations from the Scottish east coast, were compared with those of rDNA probes for A. tamarense and a universal dinoflagellate probe. Alexandrium cell numbers in field samples determined by whole-cell in situ hybridization were much lower than those determined by optical microscopy with the Utermöhi method involving sedimentation chambers, but the results were highly correlated (e.g. r 2 = 0.94; n = 6 for A. tamarense). Determination of spirolides and PSP toxins by instrumental analysis on board ship demonstrated the presence of both toxin groups in plankton assemblages collected from surface waters near the Orkney Islands, and confirmed the association of A. ostenfeldii with spirolides in northern Europe. These results show that rRNA probes for A. tamarense and A. ostenfeldii are useful, albeit only semi-quantitative, tools to detect and discriminate these species in field studies.

Subfields: Environmental Chemistry, Molecular Biology, Oceanography

View Paper: https://www.semanticscholar.org/paper/e18aa9229fffa3b39d8de0797807cb636a8f2e7b

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Citations in the corpus

The dinoflagellate genus Alexandrium(Halim) in New Zealand coastal waters: comparative morphology, toxicity and molecular genetics (2004, unknown): “, 2000) and European (John et al., 2003)”
Development of specific rRNA probes to distinguish between geographic clades of the Alexandrium tamarense species complex (2004, methodology): “FISH of whole cells from laboratory cultures was carried out as previously described ( John et al., 2003a; Groben and Medlin, 2005) using fluorescein-labelled probes.”
On the allelochemical potency of the marine dinoflagellate Alexandrium ostenfeldii against heterotrophic and autotrophic protists (2007, background): “Alexandrium species are difficult to discriminate by conventional light microscopy and A. ostenfeldii often co-occurs with other Alexandrium species, in the North Sea (John et al., 2003), Gulf of Maine (Gribble et al., 2005) and on the Nova Scotian coast (Cembella et al., 1999).”
Species boundaries and global biogeography of the Alexandrium tamarense complex (Dinophyceae) 1 (2007, background): “John et al. (2003) proposed a globally distributed ancestral population of Alexandrium, which subsequently diverged into two genetically distinct groups: the ancestors of Groups I and II, living in the waters off North America and in the tropical Atlantic, and the ancestors of Groups III, IV, and V…”
Identification and enumeration of Alexandrium spp. from the Gulf of Maine using molecular probes (2005, methodology): “ostenfeldii probe (AOST01; John et al., 2003) conjugated with FITC was used to unambiguously identify this species.”
The globally distributed genus Alexandrium: multifaceted roles in marine ecosystems and impacts on human health (2012, background): “Sequence analyses of members of the genus Alexandrium support the taxonomic distinction from other gonyaulacoid genera by unequivocally corroborating the monophyletic nature of the genus (e.g., Usup et al., 2002; John et al., 2003b; Saldarriaga et al., 2004).”