Alexandrium toxins

Figure 8. Origins of Alexandrium cultures used for the analyses of toxin composition summarized in Table I. Data from Ref. 10.

Table I. Toxin Composition of Alexandrium from the Northeast Pacific...

As discussed above, there is the possibility that toxigenesis in Alexandrium is not intrinsic but due to symbionts. Whichever proves to be the case, the observed patterns of toxin composition, whether they are for the dinoflagellate itself or the isolated assemblage of dinoflagellate and symbiont, are a basis for recognizing and distinguishing the regional populations. 

Some dinoflagellates of the genus Alexandrium produce neurotoxic compounds known as paralytic shellfish poisoning (PSP) toxins. Because these toxins can contaminate filter-feeding shellfish they may threaten public health and create economic problems for fisheries. PSP-toxins include at least a dozen saxitoxins, neosaxitoxins, and gonyautoxins (Scheme 1). 

The paralytic shellfish toxins (PSTs Fig. 5.2a) include saxitoxin (STX) as well as STX analogs such as neo-saxitoxin (neo-STX), gonyautoxin (GTX), and the decar-bamoyltoxins (Sivonen and Jones 1999). These molecules are of particular concern in marine systems, where they have been implicated in human deaths following the consumption of contaminated seafood (Van Dolah 2000). The causative agents in those cases are several genera of marine dinoflagellates that are common components of red tides (e.g., Alexandrium sp. Homer et al. 1997 Van Dolah 2000). 

Krock, B., Seguel, C.G., and Cembella, A.D. Toxin profile of Alexandrium catenella from the Chilean coast as determined by liquid chromatography with fluorescence detection and liquid chromatography coupled with tandem mass spectrometry. Harm. 

Cembella, A.D., Lewis, N.I., and Quilliam, M.A. 1999. Spirolide composition of micro-exfi acted pooled cells isolated from natural plankton assemblages and from cultiwes of file dinoflagellate Alexandrium ostenfeldii. Nat Toxins 7, 197—206. -------. 2000. The marine dinoflagellate Alexandrium ostenfeldii (Dinophyceae) as the causative organism of spirolide shellfish toxin. Phycologia 39, 61-1 A. 

Falk, M., Burton, I.W., Hu, T, Walter, J.A. and Wright, J.L.C., 2001. Assignment of the relative stereochemistry of the spirolides, macrocyclic toxins isolated from shellfish and from file cultured dmodigtWiXQ Alexandrium ostenfeldii. Tetrahedron 51, 8659-8665. 

Gallacher, S., Flynn, K.J., Franco, J.M., Bmeggemann, E.E., Hines, H.B. (1997). Evidence for production of paralytic shellfish toxins by bacteria associated with Alexandrium spp. (Dinophyta) in culture. Appl. Environ. Microb. 63 239-45. 

Lim, P. T., Leaw, C. P., Usup, G., Kobiyama, A., Koike, K., and Ogata, T. (2006). Effects of light and temperature on growth, nitrate uptake, and toxin production of two tropical dinoflageUates Alexandrium tamiyavanichii and Alexandrium minutum (Dinophyceae). /. Phycol. 42, 786—799. 

J.I. Carreto, M.O. Carignan, N.G. Montoya (2001). Comparative studies on mycosporine-like amino acids, paralytic shellfish toxins and pigment profiles of the toxic dinoflagellates Alexandrium tamarense, A. catanella and A. minutum. Mar. Ecol. Prog. Ser., 223,49-60. 

Saxitoxin (120), a paralytic shellfish poisoning alkaloid, was obtained from cultures of a red tide dinoflagellate Alexandrium sp. The toxin is also used for studies on ion channels. The biosynthesis of saxitoxin (120) involves arginine as a precursor of the guanidinio groups, whereas the perhydropurine skeleton is derived from Claisen condensation of acetate with arginine. The carbon atom in the side chain is derived from Y-adenosyl methionine. " ... 

Several species of dinoflagellate, such as Alexandrium tamarense (Prakash, 1967), Pyrodinium bahamense var. compressum (Harada et al., 1982) and Gymnodinium catenatum (Oshima et al., 1993) are known to transmit their toxins to shellfish. 

Sekiguchi, K., et al.. Accumulation and depuration kinetics of paralytic shellfish toxins in the scallop Patinopecten yessoensis ied Alexandrium tamarense. Mar. Ecol. Prog. Ser., 220, 213, 2001. 

FIGURE 8.7 HILIC-MC analyses of an Alexandrium tamarense extract containing various PSP toxins. Experiments were carrried out in SRM mode on API-III+ MS. Separations were carried out on a 5 xm Amide-80 column (250 x 2 mm i.d.), isocratically eluted with 65% B with eluent A being water and B acetonitrile-water (95 5), both containing 2 mM ammonium formate and 3.6 mM formic acid (PH 3.5). Column temperature was 20°C and flow rate 0.2 mL/min. (From Dell Aversano, C., Hess, R, and Quilliam, MA., J. Chromatogr. A, 1081, 190, 2005. With permission.)... 

Wu, Y. et al.. Determination of paralytic shellfish toxins in dinoflagellate Alexandrium tamarense by using isotachophoresis/capillary electrophoresis, J. Sep. Sci., 29, 399, 2006. 

Cembella, A.D., Bauder, A.G., Lewis, N.L, and QuiUiam, M.A. Association of the gonyaulacoid dinoflagel-late Alexandrium ostenfeldii with spirolide toxins in size fractionated plankton, J. Plank. Res., 23, 1413-1419, 2001b. 

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