Characterization of Intracellular and Extracellular Saxitoxin Levels in Both Field and Cultured Alexandrium spp. Samples from Sequim Bay, Washington

Abstract

Traditionally, harmful algal bloom studies have primarily focused on quantifying toxin levels contained within the phytoplankton cells of interest. In the case of paralytic shellfish poisoning toxins (PSTs), intracellular toxin levels and the effects of dietary consumption of toxic cells by planktivores have been well documented. However, little information is available regarding the levels of extracellular PSTs that may leak or be released into seawater from toxic cells during blooms. In order to fully evaluate the risks of harmful algal bloom toxins in the marine food web, it is necessary to understand all potential routes of exposure. In the present study, extracellular and intracellular PST levels were measured in field seawater samples (collected weekly from June to October [2004][2005][2006][2007] and in Alexandrium spp. culture samples isolated from Sequim Bay, Washington. Measurable levels of intra-and extra-cellular toxins were detected in both field and culture samples via receptor binding assay (RBA) and an enzyme-linked immunosorbent assay (ELISA). Characterization of the PST toxin profile in the Sequim Bay isolates by pre- Mar. Drugs 2008, 6104 column oxidation and HPLC-fluorescence detection revealed that gonyautoxin 1 and 4 made up 65 ± 9.7 % of the total PSTs present. Collectively, these data confirm that extracellular PSTs are present during blooms of Alexandrium spp. in the Sequim Bay region.

Year-round algal toxin exposure in free-ranging sea lions

“…For example, in Sequim Bay, Washington, the gonyautoxins GTX1, 4, GTX2, 3, and neosaxitoxin were more prevalent in Alexandrium spp. isolates compared to saxitoxin itself (Lefebvre et al 2008). Further, detection of algal toxins in the scats remains an underestimate of the full amount of toxins the sea lions were exposed to because it only reflects the toxin that was passed through digestion and does not account for the amount initially ingested.…”

Verification and quantification of saxitoxin from algal samples using fast and validated hydrophilic interaction liquid chromatography–tandem mass spectrometry method

“…in shellfish but is also extracted in surrounding water [23]. The isolation of STX could be made from any matrixes but the concentration of toxin and their stability is much lower in water samples than in algal or cyanobacteria samples.…”

Toxin profile change in vegetative cells and pellicle cysts of Alexandrium fundyense after gut passage in the eastern oyster Crassostrea virginica

“…In a few studies with bivalves, a column with activated charcoal was used to adsorb dissolved PSTs for sub sequent elution and analysis (Sekiguchi et al 2001, Suzuki et al 2003, Asakawa et al 2006. A recent study by Lefebvre et al (2008) using a receptor-binding assay (RBA) and an enzyme-linked immunosorbent assay (ELISA) found extracellular PSTs in both field samples and laboratory cultures. Activated charcoal is used to re move saxitoxin in freshwater treatments (Falconer et al 1989, Orr et al 2004, but this treatment is not 100% effective (Newcombe & Nicholson 2002, 2004, Orr et al 2004).…”

“…It is possible to use activated charcoal columns to collect the toxins, as has been done in some studies with bivalves (Sekiguchi et al 2001, Suzuki et al 2003, Asakawa et al 2006. Lefebvre et al (2008) measured the extracellular toxin levels in both field samples and laboratory cultures by receptor binding assay (RBA) and enzyme-linked immunosorbent assay (ELISA). This study showed that extracellular PSTs were present during blooms of Alexandrium spp., and in culture media.…”