Effects of Light, Salinity and Inorganic Nitrogen on Cell Growth and Spirolide Production in the Marine Dinoflagellate Alexandrium ostenfeldii (Paulsen) Balech et Tangen
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C. Maclean
Abstract
Small-volume batch cultures of the toxic marine dinoflagellate Alexandrium ostenfeldii (Paulsen) Balech et Tangen were exposed to gradients of salinity, light, and inorganic nitrogen to determine their effects on growth and toxin production. Cell growth was determined by in vivo fluorometry and microscopic cell counts, and spirolide production through the culture cycle was measured by liquid chromatography-mass spectrometry. Growth of A. ostenfeldii was a function of environmental conditions, and was strongly limited under suboptimal regimes of light ( 150 μmol m−2 s−1), salinity (≤ 15 psu), and low nutrients (≤ 20 μM initial nitrate). Cell concentration and in vivo fluorescence were highly correlated (r2 = 0.83 to 0.97, n = 6) but the relationship varied slightly depending on experimental conditions. Nevertheless, except under nitrogen limitation, fluorometry was an accurate method for tracking cell growth. The growth characteristics indicated that this estuarine isolate of A. ostenfeldii from Atlantic Canada was moderately “shade-adapted”, had a broad salinity tolerance, and could effectively utilize much higher levels of inorganic nitrogen than commonly occur in the natural environment. Analysis of toxin production and composition throughout the culture cycle showed that total concentration of spirolides in the cellular fraction of the culture (μmol l−1) increased with cell concentration, but cell spirolide quota (Qs) and toxin composition (% molar) did not vary substantially in response to variations in environmental regime. Spirolides accumulated in the growth medium, but the concentration remained low (< 15% of total) in comparison to that in the cellular fraction. This study supports the conclusion that cell growth is directly responsive to changes in environmental variables, but spirolide production is constitutive and susceptible to acclimation in culture.
Copyright © 2003 by Walter de Gruyter GmbH & Co. KG
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- Morphology of Prorocentrum minimum (Dinophyceae) in the Baltic Sea and in Chesapeake Bay: Comparison of Cell Shapes and Thecal Ornamentation
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Articles in the same Issue
- To Gerald T. Boalch, with Our Gratitude
- Growth and Survival of the Invasive Green Alga Codium fragile ssp. tomentosoides in Tide Pools on a Rocky Shore in Nova Scotia
- Structure of the Macroalgal Community Associated with the Seagrass Halodule wrightii Ascherson in the Abrolhos Marine National Park, Brazil
- The Life History of Lophothamnion hirtum (Hook. f. et Harv.) Womersley (Rhodophyta, Ceramiaceae) from Southern New Zealand
- Gametangium-like Structures as Propagation Buds in Codium edule Silva (Bryopsidales, Chlorophyta)
- Ultrastructural Study of Zoosporogenesis in the Siphonous Green Alga Derbesia tenuissima (Chlorophyta)
- Schimmelmannia venezuelensis sp. nov. (Gloiosiphoniaceae, Rhodophyta) from Venezuela
- Fatty Acids of Species in the Genus Codium
- Rheological Characteristics of Fucoidan Isolated from Commercially Cultured Cladosiphon okamuranus
- Effects of Light, Salinity and Inorganic Nitrogen on Cell Growth and Spirolide Production in the Marine Dinoflagellate Alexandrium ostenfeldii (Paulsen) Balech et Tangen
- Morphology of Prorocentrum minimum (Dinophyceae) in the Baltic Sea and in Chesapeake Bay: Comparison of Cell Shapes and Thecal Ornamentation
- Ordinal Placement of Selected Marine Dothideomycetes Inferred from Small Subunit Ribosomal DNA Sequence Analysis
- Meetings
