Diarrheic Shellfish Toxins Research Articles

Recycling of macronutrients from sea to land using mussel cultivation

The presence of diarrheic shellfish toxins (DST) has been the main obstacle to mussel cultivation in Sweden. Monitoring of DST concentrations in mussels by HPLC for 12 years has shown great geographical and seasonal differences. Furthermore, individual mussels on the same farming strip may differ by a factor as great as 16. DST levels are usually low in summer, rise in September, remain high in the winter and vanish after the start of the spring bloom. A part of the Bohuslan fjord system north of the island Orust, which is secluded from the open sea by shallow sills, regularly shows low DST concentrations. This basin is among the most eutrophicated parts of the Bohuslän coastline. Cultivation of mussels in this area has been calculated to reduce the eutrophication, and results of field-tests support this view. As a consequence, a strategy for sea-gardening is being developed in which the presence of nutrients with primary production in the sea and cultivation of mussels are planned to balance one another.

Detection of Ciguatera and Diarrheic Shellfish Toxins in Finfish and Shellfish With Ciguatect Kit

Abstract The Ciguatect test kit for the detection of ciguatoxin, okadaic acid, and related polyether compounds, based on solid-phase immunobead assay technology, was developed for rapid screening of toxic fish and shellfish in harvesting areas and the marketplace. Earlier formats, based on radioimmunoassay and enzyme-linked immunosorbent assay (ELISA) technology, were used successfully to identify and separate ciguatoxic fish harvested from Hawaiian waters. The new format utilizes a membrane attached to a plastic strip, immunobead solution, and a user-friendly readout. Multiple formats of the test kit, including a rapid extraction method (REM) and ELISA, were demonstrated to be more sensitive than the mouse assay for detection of ciguatera-related compounds. Depending on the format used, the level of detection can be as low as 50 pg okadaic acid per gram of tissue. The test kit has been used to map ciguatoxic and nontoxic fishing areas around the islands of Hawaii through the use of a biomarker and the monitoring of toxic fish obtained from Pacific and Caribbean regions. Ciguatera-related toxins can be detected directly on fish flesh or after extraction by traditional procedures or the newly developed REM. Initial applications of the test kit to monitor diarrheic shellfish poisoning (DSP)-related toxins in mussels before, during, and after Dinophysis sp. blooms and during depuration operations were successful. The Ciguatect methodology can be used to monitor reef fishing areas for ciguatera potential, shellfish beds for DSP toxins, and shellfish depuration operations for elimination of DSP toxins and to screen for toxic fish and shellfish in the marketplace.

Monitoring of Diarrheic Shellfish Toxins in Mussels

Monitoring of Diarrheic Shellfish Toxins in Mussels

On the Presence of Diarrheic Shellfish Toxins in Fish

On the Presence of Diarrheic Shellfish Toxins in Fish

Occurrence of okadaic acid, a major diarrheic shellfish toxin, in natural populations ofDinophysis spp. from the eastern coast of North America

Okadaic acid, one of the principal toxin components implicated in cases of diarrheic shellfish poisoning (DSP), was identified for the first time in natural phytoplankton assemblages from North American waters. During periods in late summer when significant quantities of okadaic acid were detected in net haul samples in the lower estuary and Gulf of St Lawrence in eastern Canada, the phytoplankton community consistently contained species of the dinoflagellate genusDinophysis Ehrenberg. The presence of okadaic acid was detected by screening dinoflagellate extracts with an enzyme-linked immunological assay (ELISA); positive results were confirmed by reverse-phase high-performance liquid chromatography (HPLC) separation, followed by fluorescence detection. Okadaic acid was only found in phytoplankton samples in which the photosynthetic dinophysoid speciesD. norvegica andD. acuminata were prominent; blooms of the related heterotrophic speciesD. rotundata exhibited no trace of okadaic acid, nor other suspected DSP components.

Toxic effect of free unsaturated fatty acids in the mouse assay of diarrhetic shellfish toxin by intraperitoneal injection.

The acetone extracts from three samples of the hepatopancreas of the poisonous scallops obtained on the Okhotsk Coast of Hokkaido Island were fractionated into two parts, hexane soluble fraction (fraction H) and 85% aqueous ethanol soluble fraction (fraction E) by partition to two layers. The majortoxic components in the mouse assay of “diarrheic shellfish toxin” by intra-peritoneal injection were found to be free unsaturated fatty acids showed the following toxicity in MU per g, 18:1 n-9 35, 18:2 n-6 83, 18:3 n-3 167, 18:4 n-3 83, 20:5 n-3 167, and 22:6 n-3 83, respectively. Toxicity of the fraction Hin MUper g was much lower than that of the fraction E. However, the toxicity of the fraction H per 1 g of the hepatopancreas was about twice that of the fraction E, since the fraction Hwas much more abundant than the fraction E in the hepatopancreas. The method for the assay of the diarrhetic shellfish toxin must be reexamined by considering the toxic effect of the free unsaturated fatty acids.