Gambierdiscus toxicus

Although Gambierdiscus toxicus was the first dinofiagellate species to be involved in the genesis of ciguateric toxins, other toxic dinofiagellates have been... 

Cultures of Gambierdiscus toxicus have been obtained in several laboratories (14,17-19). These cultures produce large amounts of maitotoxin and low amounts of lipid-soluble CTx-like toxin. However, in most cases, this toxin has not been unequivocally identified as CTx. The only firm evidence that cultures of Gambierdiscus toxicus produce CTx was provided by Baden et al. (20) who used radioimmunoassays and electrophysiological experiments to characterize the toxin. It is possible that cultured Gambierdiscus toxicus produce only trace amounts of CTx and that levels of production comparable to those found in natural populations are dependent on yet undefined environmental parameters. 

Complex polyether paralytic neurotoxins that bind to sodium channels of nerve and muscle cells causing muscle contractions. They are heat stable (not destroyed by cooking or freezing) white solids obtained from dinoflagellates Gambierdiscus toxicus). 

Dinoflagellates Dinophysis spp., Prorocentrum lima Diatoms Pseudo-nitzschia spp. Dinoflagellates Protoperidinium spp. Epibenthic dinoflagellates Gambierdiscus toxicus Possibly Ostreopsis spp. Coolia spp. or Prorocentrum spp. 

Murata, M., et ah. Structures and configurations of ciguatoxin from the moray eel Gymnothroax javanicus and its likely precursor from the dinollagellate Gambierdiscus toxicus, J. Am. Chem. Soc., 112, 4380, 1990. 

Satake M, Murata M, Yasumoto T, The structure of GTX3G, a ciguatoxin congener isolated from cultured Gambierdiscus toxicus, Tetrahedron Lett 34 1975-1978, 1993. 

Figure 6. Maximum abundance of Gambierdiscus toxicus found on several species of macroalgae at localities in the northern Grenadine Islands (Mustique is shown to scale and enlarged). Redrawn from Ref. 49.

Preliminary results on toxicity of 3 species of Caribbean dinoflagellates have been reported, namely those on Gambierdiscus toxicus (25), Prorocentrum concavum (as cf. lima) (26), and mexicanum (as rhathymum) (27). A more detailed description of the effects of ether-soluble and water-soluble toxins from the same strain of toxicus on guinea pig ilea are presented elsewhere in... 

Our observations strongly suggest that Prorocentrum concavum and Gambierdiscus toxicus are major contributors of toxins to the reef and inshore ecosystems. We believe that these two species produce at least 4 (up to 7) separate toxins which may eventually... 

Lipid-Extracted Toxins from a Dinoflagellate, Gambierdiscus toxicus... 

Crude and three diethyl ether extracted, acetone treated, fractions were isolated from large-scale cultures of Gambierdiscus toxicus. Crude extracts at. 04 mg/ml inhibited the histamine contraction response in smooth muscle of the guinea pig ileum. Three semi-purified fractions at 5 ng/ml, effectively inhibited the guinea pig ileum preparation. Two of these fractions followed Michaelis-Menten kinetics for a competitive inhibition. The third fraction inhibited in a non-reversible manner. This study has established the presence of three lipid extracted toxins in toxicus, outlined a method for their assay in small quantities, and identified at least two of the effects of these toxic extracts in animals. 

A dinoflagellate, Gambierdiscus toxicus has been reported to be the likely progenitor of ciguatoxin in the South Pacific (13-15). Recently, Tindall, (26), Miller, ]]) and Carlson, (18) reported on toxic extracts from G. toxicus and two species of Prorocentrum from the Caribbean. iHe physiological action of toxic extracts from G, toxicus were found to be similar to those induced by toxic extract from Scomberomorus cavalla (Kingfish) from the same region (19). 

Table 1. Column Chromatographic Separation of 485.21 mg of ESAP from Gambierdiscus toxicus (350G)...

Figure 1. Flow diagram for the isolation of toxins Gambierdiscus toxicus.

Figure 1. The effects of soil and macroalgal extracts on (a) highest cell concentration and (b) maximum growth rate of Gambierdiscus toxicus, grown in natural seawater (ESNW) medium (shaded bars) or in artificial seawater (ESAW) medium (open bars). Vertical brackets indicate standard errors. CNTL=controls (ES medium without, added extracts) SE soil extract DI=Dictyota extract CH=Chaetomorpha extract TU Turbinaria extract ...

Figure 2. Growth of Gambierdiscus toxicus in (a) ESNW and (b) ESAW both supplemented with soil and macroalgae extracts. Controls ( ), Chaetomorpha extract ( ), Dictyota extract (A), Turbinaria extract ( ), and soil extract (O).

The maitotoxin was isolated from Gambierdiscus toxicus by Dr. Yasumoto. 

---