Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Mollusk toxins

In the early 1960s, the secretion of a shell-less, brightly colored Hawaiian mollusk, Phyllidia varicosa Lamarck, was investigated by a marine biologist [70]. It seemed fitting that our interest in marine toxins led to an examination of the chemical constituents. [Pg.72]

Significant concentrations of cyanotoxins have been found to accumulate in the tissues of macroinvertebrates such as mollusks and crustaceans, presenting an indirect route of exposure for invertebrates, fish, and aquatic mammals at higher trophic levels (Negri and Jones 1995). In natural systems, mortality among benthic invertebrate herbivores is probably low because most bloom-forming bacteria are planktonic and only periodically come into contact with the benthos. Nevertheless, Kotak et al. (1996) determined that enhanced mortality of snails at the end of a bloom cycle in Canadian lakes was due to consumption of Microcystis cells that had formed a scum on the surface of macrophytes. Oberemm et al. (1999) found that aqueous microcystins, saxitoxins, and anatoxin-a all resulted in developmental delays in fish and salamander embryos. Interestingly, more severe malformations and enhanced mortality were observed when larvae were exposed to crude cyanobacterial extracts than to pure toxins applied at natural concentrations (Oberemm et al. 1999). [Pg.112]

Saxitoxins are water-soluble compounds that prevent proper nerve functioning. They are produced in nature by plant-like marine protozoa called dinoflagellates. Humans typically acquire such toxins by eating bivalve mollusks fed on dinoflagellates. A terrorist would likely deliver a saxitoxin as an aerosol or use it as a poison to contaminate food or water. [Pg.107]

Marine biotoxins are produced by naturally occurring marine phytoplankton. Marine algal toxins are responsible for more than 60,000 intoxication/year with an overall mortality of about 1.5%. These substances can accumulate in aquatic animals intended for human consumption like filter-feeding mollusks. The toxins are thermoresistant compounds therefore, normal cooking, freezing, or smoking cannot destroy them. [Pg.7]

Prialt [Fig. 6] is a synthetic copy of a toxin from the Magician s cone snail. Conus magus, a mollusk from the Indo-Pacific region. This is also one of the first pharmaceuticals that demonstrate the promise that marine life, particularly invertebrates, holds for drug developers. [Pg.145]

Shellfish (filterfeeding mollusks) Mussels, clams, oysters, scallops Several kinds of toxin taken up from plankton (dinoflagellate) See below ... [Pg.164]

Com shell is carnivorous snail belongs to the world s largest genus of marine invertebrates (Conus) under the phylum of mollusks (Bingham et al., 2010). Com shell species are able to secrete venom, which contains com shell toxins (conotoxins) of bioactive peptides called as conopeptides (Layer and McIntosh, 2006). Different structural classes of... [Pg.160]

If preparation of an animal is done too quickly or without proper care, some natural compounds may remain in the specimen. Even though these compounds were liquid when the animal was alive, they may still be toxic. These include venom in the fangs of insects, snakes, some mollusks, and gila monsters. Mollusk shells in a dry collection may contain toxin if the body of the animal was not removed, but rather left to dessicate inside. [Pg.160]

Before the eighties research dealing with prosobranchs concentrated on toxic compounds present in shellflsh. Since the majority of the metabolites that can be isolated from mollusks are of dietary origin, it would be difficult to consider shellfish toxins as secondary metabolites of shellfish only. [Pg.19]

Six a-conotoxins have been isolated from C. geographus, two of which target the neuronal nAChRs, suggesting that both muscle and neuronal subtypes are important in prey capture. Often multiple a3/5-conotoxins are found within the venom of one mollusk, although the reason for having multiple toxins targeting one receptor is not clear. [Pg.517]

Since the year 2000, several international expert groups have undertaken risk assessments of marine algal toxins in bivalve mollusks. In 2001, a Working Group (WG) on Toxicology of diarrheic sheUflsh... [Pg.4]

Yessotoxins (YTXs) were discovered in shellfish extracts together with toxins from the OA group in 1987 [46]. Since the YTXs contribute to the outcome of the MBA for DSP toxins, they were initially included in the DSP toxin complex. The main producer of YTXs is the dinoflagellate Protoceratium reticulatum. YTXs are detected in bivalve mollusks in many parts of the world, like Japan, New Zealand, Australia, Canada, Norway, Italy, and the United Kingdom [3]. Many analogues of YTX are described, and new ones are frequently reported. [Pg.13]

Sampling plans to check for the presence of toxin-producing plankton in production and relaying waters and for biotoxins in live bivalve mollusks must take particular account of possible variations in the presence of plankton-containing marine biotoxins. Sampling must comprise of... [Pg.67]

Periodic sampling to detect changes in the composition of plankton containing toxins and their geographical distribution. Results suggesting an accumulation of toxins in mollusk flesh must be followed by intensive sampling. [Pg.67]

With regard to the monitoring of plankton, the samples are to be representative of the water column and to provide information on the presence of toxic species as well as on population trends. If any changes in toxic populations that may lead to toxin accumulation are detected, the sampling frequency of mollusks is to be increased or precautionary closures of the areas are to be established until results of toxin analysis are obtained [71]. [Pg.67]

MU [144]. A second study in Taiwan measured toxin levels in the implicated marine organisms for six outbreaks with toxin varying between 13 (for gastropod mollusks) and 1200 (for puffer fish roe) MU/g of tissue unfortunately the amount of fish or mollusk eaten was not reported [137]. A study in Madagascar found that four persons were ill and one died following ingestion of tissue with a toxin level of 16 MU/ g of tissue [146]. The lethal dose for humans has been estimated as... [Pg.95]

In 2006, an interlaboratory exercise was organized by the Community Reference Laboratory for Marine Biotoxins (CRLMB) to evaluate its fitness for purpose for the Official Control of PSP toxins in the EU laboratories [41]. Eighteen European Union (EU) laboratories took part in the study. The participants had to analyze six bivalve mollusks samples with various PSP toxic profiles. The performance of the participant laboratories in the application of the 2005.06 AOAC Official... [Pg.184]

The toxin profiles in contaminated shellfish clearly point to a structural modification of the absorbed YTX or homoYTX within the mollusk. It is to be noted, however, that, on the basis of the results reported in Table 13.3, the extent of the YTX metabolism within the mollusk greatly depends on the species of the host. Anyway, some YTX analogs, which are reported as very minor constituents of the algal extracts, are present in large quantities in contaminated shellfish 45-hydroxy YTX... [Pg.297]

The problems observed with the original mouse bioassay of Yasumoto et al. (1978) have led to several modifications. As in the case of YTXs, the difference in their dangerousness compared with that of the DSP toxins is substantial. OA is considered a most harmful compound because of its potent tumor promoting activity, whereas YTX, whose toxicology still presents many blind spots, is of significantly lower oral toxicity. Nonetheless, YTX and OA show an almost equal lethal potency when tested through the mouse bioassay. On account of the relative harmfulness to public health, the European Uiuon has recently established different allowance levels in shellfish for DSP-toxins and YTXs (16 g of OA and 100 g of YTX in 100 g of mollusk, respectively). ... [Pg.301]

Hwang, D.F., Lin, L.C., and Jeng, S.S. 1992b. Variation and secretion of toxin in gastropod mollusk Niotha clathrata. Toxicon 30, 1189-1194. [Pg.226]

Prey used in experiments should be those that co-occur with the predator in question because toxins may be targeted to certain types of common prey. Kobayashi et al. (1989) note that venoms from fish eating cone snails are active against laboratory mice, whereas those from cone snails that feed on mollusks or worms are not. [Pg.92]

Ray, S.M. D.V. Aldrich. 1967. Ecological interactions of toxic dinoflagellates and mollusks in the Gulf of Mexico. In Animal Toxins, eds. F.E. Russell P.R. Saunders, pp. 75-83, Pergamon, Oxford. [Pg.135]


See other pages where Mollusk toxins is mentioned: [Pg.78]    [Pg.472]    [Pg.297]    [Pg.297]    [Pg.137]    [Pg.278]    [Pg.410]    [Pg.235]    [Pg.172]    [Pg.217]    [Pg.321]    [Pg.1603]    [Pg.68]    [Pg.517]    [Pg.144]    [Pg.19]    [Pg.5]    [Pg.67]    [Pg.177]    [Pg.551]    [Pg.142]    [Pg.170]    [Pg.226]    [Pg.37]    [Pg.526]    [Pg.41]    [Pg.243]   


SEARCH



Mollusks

© 2024 chempedia.info