Gonyaulax toxicity

Surprisingly, most of the definitive cell biology on toxic dino-flagellates has yet to be observed, understood and described. What was once thought to be the major causative genus, Gonyaulax, is now known to contain a wide variety of similar strains/ varieties/species ( ). ... 

Figure 4. Global distribution of toxic gonyaulacoid species and some close relatives. A.-Protogonyaulax acatenella. C.-P. catenella. F.-P. fratercula. H.-P. cohorticula. K.- "Gonyaulax" kutnerae.

In his meticulous exploration of methods for his thesis research, Proctor ( ) noted that the toxicity (MIP) of cell free extracts of Gonyaulax increased following heating at low pH. Hall (1,22) further explored this increase in potency, referring to it as Proctor enhancement, and demonstrated that it was primarily due to the hydrolysis of sulfamate to carbamate toxins. It was found that heating at 100 C for 5 minutes in aqueous HCl with a free acid concentration of 0.1 M is sufficient to insure complete hydrolysis and attain maximum MIP. 

The purpose of this paper is to examine our present knowledge of the cysts of the toxic Gonyaulax species to see whether these hypothetical considerations are valid representations of the actual roles cysts play in toxic dinoflagellate blooms and shellfish toxicity. 

We must recognize that the "easy" answers provided by this dormant life cycle stage do not apply to all situations. In colder temperate waters, it is a reasonable assumption that cyst germination probably introduces the first toxic Gonyaulax cells into the water in some locations, but the subsequent transport of these cells over long distances must be considered a viable "seeding" alternative to the direct input of new cells from underlying sediments. 

The fate of the toxic Gonyaulax species in low-nutrient environments is also poorly understood. On the one hand, G. tamarensis cells can persist in older cultures for months without dividing, presumably under impoverished nutrient conditions. On the other hand, encystment has been observed in natural waters at relatively high nutrient concentrations (18). We thus have no firm foundation on which to base the conclusion that toxic Gonyaulax species encyst to survive the temperature or nutrient variations of temperate coastal waters. Clearly there are many phytoplankton... 

There are a variety of ways that toxic Gonyaulax cells could be introduced to areas with no previous history of PSP, and most of these involve cysts. The most common claim is that transport of an established motile population by tidal and large-scale circulation patterns permits a species to deposit cysts in new areas as seeds for future blooms (1, 9, 10, 31). Within this framework, the cyst is most important in those areas where advection of... 

In general, it may never be possible to prove that species dispersal is facilitated by dredging, shellfish transplants,or boat traffic. Here again we are faced with mechanisms that are theoretically possible but that may be of minor practical concern relative to the introduction of cysts to new areas through advective transport of established blooms. There is little doubt that this latter mechanism has been, and will continue to be, of major importance to the geographic distribution of the toxic Gonyaulax species. 

Bloom - Gonyaulax Population and PSP in Mussels. A bloom of catenella, which started in mid-June, peaked in July with PSP levels in bay mussels reaching a maximum toxicity level of 2139 y g toxin/ 100 g meat (Figure 4). As observed in 1981, the G. catenella cells were heavily parasitized by ceratii during the decline of the bloom. 

Our first attempt was the feeding of commercially available [guanido-l C]-L-arginine to the cultures of Gonyaulax tamarensis (Ipswich strain). The toxin fraction was isolated and further fractionated to the pure toxins (7). Figure 1 shows an example of the elution pattern of the toxins from a Bio-Rex 70 column. A good correlation between the toxicity and radioactivity was observed. 

A phytoplanktivorous fish would have to eat about one or two million excavata cells, which means clearing only about 100 mL or so of red water which can contain many millions of Gonyaulax cells per liter. A zooplanktivorous fish would only have to eat 1 g or so wet weight of zooplankton during a toxic Gonyaulax bloom (see Table IV). Filter-feeding shellfish commonly acquire 6000 pg toxins per 100 g of... 

The toxin content of Bay of Fundy zooplankton has reached high levels in most years since 1977 (Table IV). Yet, curiously, herring kills have not been observed in years other than 1976 and 1979. The occurrence of kills may depend upon the temporal and spatial overlapping of dense Gonyaulax blooms, highly toxic zooplankton, and actively feeding herring. 

Fish. The major impact of toxic Gonyaulax blooms and paralytic... 

Exogenous. Tetrodotoxin is not produced by the animal but arises from the food chain in some manner, for instance, similar to the way saxitoxin is concentrated by shellfish that ingest the toxic Gonyaulax dinoflagellates. 

Saxitoxin (= mussel/clam Gonyaulax catenella, V-INa+ CH blocker [toxic]... 

Moestrup, 0., and Hansen, P.J. 1988. On the occurrence of the potentially toxic dinoflagellates Alexandrium tamarense (=Gonyaulax excavatd) and4. ostenfeldii in Danish and Faroese waters. Ophelia 28,195—213. 

---