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At least 901 records · Page 50Linked to original sources
PubMed2002

Transport of the organic cations gonyautoxin 2/3 epimers, a paralytic shellfish poison toxin, through the human and rat intestinal epitheliums.

The aim of this work is to study the mechanisms involved in gonyautoxins (GTXs) intestinal absorption. For this purpose, we studied the transport of GTX 2/3 epimers by intestinal epithelial cell lines (IEC-6 and Caco-2) cultured on polycarbonate filters. Specific transport was calculated by subtracting from the flux of GTX 2/3 measured at 37 degrees C that occurring at 4 degrees C, this being an indication of transcellular transport. The transcellular apical-to-basolateral (A-B) flux in Caco-2 cell monolayers, was greater than that in the opposite direction, suggesting the involvement of an active transport system favoring the absorption of the toxin. However, in IEC-6 cells the transcellular basolateral-to-apical (B-A) specific transport of the toxin was greater than that in the opposite direction. The A-B and B-A fluxes were, respectively, 127 +/- 26 and 205 +/- 23 nmol/min, suggesting the presence of a prevalent secretive process of the toxin in IEC-6 cells. The A-B transport of GTX 2/3 epimers in Caco-2 cells, but not in IEC-6 cells, was partially Na(+)-dependent and significantly inhibited by adenosine. TEA and verapamil in both Caco-2 and IEC-6 cells failed to affect the A-B and B-A transport of GTX 2/3 epimers. Cyanine in IEC-6 cells, but not in Caco-2 cells, increased the A-B flux of the toxin, suggesting the involvement of the organic cation transporter in the absorption of GTX 2/3 epimers. The mitochondrial energetic uncoupler 2,4-dinitrophenol significantly inhibited the A-B and the B-A transport in both cell lines. In conclusion, IEC-6 cells secrete actively the toxins, whereas Caco-2 cells were found to absorb the toxins in a process that was inhibited in the presence of adenosine and the absorption was dependent of Na(+).

Adenosine↗
PubMed2002

Depuration and anatomical distribution of the amnesic shellfish poisoning (ASP) toxin domoic acid in the king scallop Pecten maximus.

The depuration kinetics of the domoic acid of four body fractions (digestive gland, adductor muscle, gonad+kidney and gills+mantle) of the scallop Pecten maximus was studied over 295 days. The scallops, which had acquired the toxins during a Pseudo-nitzschia australis episode that took place the week before the beginning of the experiment, were maintained in tanks with running seawater. All the body fractions, except the adductor muscle, decreased their domoic acid burden throughout the experiment. The amount of toxin in the muscle dropped sharply at the start of the experiment but increased again at the end, to levels that were higher than the initial ones. Several dynamic models of depuration kinetics, which included the depuration of each fraction (excluding the adductor muscle) and the transfers between them, were constructed, implemented and fitted to the data to obtain their parameters. The estimated depuration rates were very low, both considering and not considering the transfer of toxin between organs or the effect of weight loss. There were strong differences in the domoic acid burden of the body fractions studied but not between their depuration rates. No net transfer from the digestive gland, the tissue with highest domoic acid concentration, to the other fractions was found, as the inclusion of these processes in the models produced only a marginally better fit to the data. The depuration of domoic acid was slightly, but significantly, affected by biomass. Weight loss induced domoic acid loss, suggesting that part of the depuration may be produced by the direct loss of bivalve cells. The concentration or dilution effect, due to decreases or increases in biomass, documented for other species and toxins, has little importance in Pecten maximus.

Animals↗
PubMed2000

[Presence if a new oyster predator, Ocinebrellus inornatus (Recluz, 1851), in the shellfish culture bay of Marennes-Oleron].

The muricid gastropod, Ocinebrellus inornatus, originates from the coasts of the Korean Sea and southern Japan. This species has been regularly sampled in the bay of Marennes-Oléron (France) since spring 1997, and allowed us to validate the taxonomic status of a previous report of the species in the bay in April 1995. O. inornatus was sampled only in the bay of Marennes-Oléron and has not been observed in the other areas along the Charente-Maritime coast. O. inornatus lives mainly in the same biotope as the local muricid Ocenebra erinacea (i.e. the level of Fucus serratus between MLWN and ELWS) Now, this alien species seems to be very well settled in the bay of Marennes-Oléron, where it causes damage to the farming oyster beds. In the areas of highest densities of Ocinebrellus inornatus, the local species Ocenebra erinacea is observed in comparatively reduced numbers. The probable causes of introduction of O. inornatus in the bay are discussed.

Animals↗
PubMed1975

Taxonomic difficulties in red tide and paralytic shellfish poison studies: the "tamarensis complex" of Gonyaulax.

The type illustrations of the dinoflagellate Gonyaulax tamarensis contain an apparent reversal of the epithecal plates. Furthermore a culture from the type locality has been found not to be toxigenic. These two features have led a recent author to doubt the appropriateness of the allocation of toxic populations in the North Atlantic to this species or a variety of it (var. excavata Braarud). The latter has been raised to the status of a distinct species but the wrong name has been applied to it (G. excavata) as, according to the rules of priority, it should be G. phoneus (Woloszynska & Conrad) nov. comb. A history of this confused situation is provided. The criteria by which other similar species are recognised are summarised. The necessity for further study on the specific distinction of these taxa is stressed. G. conjuncta has been so inadequately described or rejected. Variability in the plate pattern of a culture of G. tamarensis var. excavata from British Columbia is illustrated and its bearing on the taxonomy of the group discussed. The presence of this toxic variety on the west coast of N. America is a new record for the Pacific Ocean.

Animals↗
PubMed1975

The determination of arsenite and arsenate ions in fish and shellfish by selective extraction and polarography.

Arsenite ion, as arsenic trichloride was extracted into benzene from strongly acidified tissue homogenates. Following this, arsenite was extracted from the benzene into water, made up in 1N HCl and analyzed polarographically. Arsenate ion, left in the homogenate after arsenite extraction is isolated in exactly the same way following treatment of the homogenate with cuprous ion to reduce arsenate to arsenite ion. Treatment of the acidified homogenate with cuprous ion prior to extraction gives a homogenate which is readily analyzed for total "inorganic" arsenic. The method was efficient to a maximum level of about 20 mug inorganic arsenic since at higher levels lower recoveries were found. Analysis of a variety of marine biological specimens, with levels of total arsenic up to 40.5 ppm, indicated little of this arsenic was present in an inorganic form. Post mortem reduction of arsenate to arsenite was found to occur rapidly in fish tissue.

Animals↗
PubMed1995

A multistate outbreak of oyster-associated gastroenteritis: implications for interstate tracing of contaminated shellfish.

In November 1993, clusters of gastroenteritis in six states following oyster consumption were investigated to identify common features, and stool samples were obtained to identify a pathogen. Efforts were made to account for all potentially contaminated oysters using harvest tags and the interstate recall system. Consumption of oysters was associated with illness in 10 clusters; no other food was implicated. A Norwalk-like virus was detected by electron microscopy in 9 of 18 samples and by reverse transcription-polymerase chain reaction in 20 of 26 samples from 6 clusters. Nucleotide sequences of a 123-bp fragment from all specimens were identical, consistent with a common source outbreak. Implicated oysters were harvested from the Louisiana coast between 9 and 12 November. Although some were recalled and destroyed, most oysters harvested from the area during this time remain unaccounted for. Current regulations and commercial practices need to be revised to permit thorough tracing and recall of contaminated oysters and to improve control of future epidemics.

Animals↗