Acid In Mussels Research Articles

Carbon Isotope Compositions of Fatty Acids in Mussels from Newfoundland Estuaries

This paper examines the carbon isotopic compositions of free fatty acids of two species of mussels (i.e. Mytilus edulis and Modiolus modiolus) from two estuarine environments around Newfoundland. Gas chromatography and conventional isotope ratio mass spectrometry were employed to characterize bulk fatty acids and gas chromatography/combustion/isotope ratio mass spectrometry was utilized to characterize the carbon isotope compositions of individual fatty acids. The bulk fatty acid distribution (dominance of 16:0, 20:5n3, 22:6n3 and 16:1) and carbon isotopic compositions (-27·3 to -25·8 per mil) indicate a dominant marine phytoplankton dietary source for the mussels. In contrast to the narrow range of bulk fatty acid δ13C values, up to 7 per mil variation in δ13C of individual fatty acids was observed. In general, saturated fatty acids are isotopically heavier than corresponding mono- and polyunsaturates, consistent with previously suggested kinetic isotope effect associated with de novo desaturation reactions. The depletion of 13 C in 18:4n3 compared with 22:6n3 and 20:5n3 indicates a distinct dietary source for 18:4n3. The present study shows the potential for detailed assessment of carbon flow in benthic ecosystems using fatty acids and other compound classes by gas chromatography/combustion/isotope ratio mass spectrometry.

Chemistry of the shellfish toxin domoic acid: characterization of related compounds

Five new compounds related to the neurotoxin domoic acid have been characterized by spectroscopic methods. They include a diastereoisomer that occurs naturally with domoic acid in mussels and four hydrogenation products. The stereochemistry of the two epimeric tetrahydro derivatives could not be assigned on the basis of the NMR data alone because of high conformational flexibility. However, a clear-cut assignment was possible by molecular modelling in combination with the NMR data.

Okadaic acid in mussels of Adriatic sea

The diarrethic shellfish poisoning from mussels, collected in the main producing areas in the seawater off the coast of Emilia-Romagna (Italy), has been investigated. The ether soluble material from hepatopancreas of highly toxic mussels ( Mytilus galloprovincialis) was partitioned between n-hexane and methanol-water 9:1. The hydromethanolic phase was successively subjected to repeated chromatographic separations (SiO 2, Sephadex LH-20 and reversed-phase HPLC). Following the toxicity of each fraction by mouse lethality test, the presence of okadaic acid has been evidenced through 1H NMR spectroscopy. The investigation of two further toxic fractions is still in progress. The obtained results represent an initial contribution to current Italian legislation and to future health measures to be defined at European Community level.

High-performance liquid chromatography of okadaic acid and free fatty acids in mussels

A high-performance liquid chromatographic method developed for the determination of both okadaic acid (OA) and free fatty acids (FFA) was used for analysing mussel samples collected in the Gulf of Trieste. OA and FFA extracted from mussel hepatopancreas were derivatized prior to their chromatographic separation and spectrofluorimetric detection. 9-Chloromethylanthracene (CA) was used as a fluorescent labelling agent. The presence of toxic fatty acids ( e.g., linolenic acid), which may interfere with the bioassay of diarrhoetic shellfish poisoning (DSP) toxins, in the lipidic fraction of the extract was observed, whereas no OA was detected in the analysed samples.

Dynamic Model of the Flux of Domoic Acid, a Neurotoxin, through a Mytilus edulis Population

A one-compartment computer simulation model was developed to quantify and characterize the accumulation of the neurotoxin domoic acid in blue mussel (Mytilus edulis) in Cardigan Bay, Prince Edward Island, Canada. Comparison of simulation results with field abundances of Nitzschia pungens f. multiseries Hasle, a diatom implicated in the production of domoic acid, and with measurements of domoic acid within Nitzschia cells indicates that the rate of accumulation of domoic acid in mussel tissue during peak bloom conditions may involve unexpected physiological feedback processes. At extremely high concentrations of toxin (> 300 ppm) observed in toxic Mytilus episodes off eastern Prince Edward Island in 1987 during the peak of Nitzschia bloom, the depuration of domoic acid seemed to be suppressed; this may have been responsible for the observed abnormal buildup of toxin in the mussels. In 1989 the amount of domoic acid produced by N. pungens was slightly lower, but the levels of domoic acid in Mytilus were much less than in 1987. These results suggest that a crucial factor in prediction of high levels of domoic acid in mussels may be identification of changes in their physiology and metabolism which suppress depuration rates.

Lipid composition of the toxic marine diatom, Nitzschia pungens

A bloom of Nitzschia pungens f. multiseries was the source of domoic acid in mussels which caused an outbreak of amnesic shellfish poisoning in Canada. Because algal lipid and fatty acid production is known to vary during blooms we examined the lipid content, the lipid class composition and the fatty acid composition of N. pungens grown under nutrient-replete and silicon-limited conditions. The total lipid content ranged from 13 to 30 pg per cell; the major lipid classes were polar lipids (including phospholipids) and free fatty acids. GC analysis of total fatty acid methyl esters showed that the proportion of total dienes, trienes and tetraenes increased with silicon limitation at the expense of saturated fatty acids. N. pungens had unusually high contents of 16:4n1 which increased with silicon limitation to 11±1% of the total fatty acids. High proportions of this polyunsaturated fatty acid may thus be a useful marker of N. pungens in natural plankton blooms and associated food web organisms. Lipids extracted from cultured N. pungens may also be a useful source of 16:4n1 for biomedical studies.

Liquid Chromatographic Determination of Domoic Acid in Mussels, Using AOAC Paralytic Shellfish Poison Extraction Procedure: Collaborative Study

A liquid chromatographic method using the AOAC paralytic shellfish poison (PSP) extraction procedure for domoic acid, a marine toxin, in mussel tissue was collaboratively studied in 10 laboratories. Domoic acid is extracted by boiling the homogenized tissue for 5 min with 0.1N HCl. The mixture is cooled, diluted to a known volume, and then centrifuged. An aliquot of the supernate is diluted, filtered, and analyzed by reverse-phase liquid chromatography with a mobile phase containing acetonitrile and water adjusted to about pH 2.5. Each collaborator received a prepared standard solution, a practice sample, and 7 randomly numbered unknown samples (1 blank mussel tissue, 1 spiked at 14.1 micrograms domoic acid/g, 1 spiked at 18.9 micrograms/g, and duplicate samples with naturally incurred domoic acid at 75 micrograms/g and at 186 micrograms/g). Five of the laboratories had little or no experience in domoic acid analysis. Ten of 11 laboratories completed the study and submitted results. Two individual values out of a total of 70 were found to be outliers. Mean recovery of domoic acid from the spiked extracts was 75%. Relative standard deviations between laboratories (RSDR) ranged from 7.5 to 19.4%; within-laboratory RSDs (RSDr) for the 2 blind duplicate pairs were 1.9 and 4.8%. The detection limit was about 1 microgram domoic acid/g. The method has been adopted official first action by AOAC.

Capillary Electrophoresis for Detection and Quantitation of Domoic Acid in Mussels

Abstract Capillary electrophoresis (CE) was utilized to quantitate the domoic acid content in mussel tissues. The analyses were conducted on samples obtained by aqueous extraction of the tissues. Lipids were removed from the extract in order to facilitate electroendomosis and to shorten analysis time. Satisfactory resolution of domoic acid was accomplished with 300 mM CAPS buffer at pH 10.25 or 10.30 and the electrophoresis time was less than 10 minutes per sample. A procedure was devised for quantitation of domoic acid in the mussel extracts. Application of this procedure on a sample of naturally contaminated mussel homogenate yielded results in close agreement with those reported in the literature.

Domoic acid and the eastern Canadian molluscan shellfish industry

This report summarises the events surrounding the food poisoning associated with the occurrence of domoic acid in mussels ( Mytilus edulis) from Cardigan Bay, Prince Edward Island, in the fall of 1987. A possible chain of events leading to domoic acid accumulation in mussels is suggested; the epidemiology of domoic acid poisoning is reviewed briefly and its toxicology is discussed. The implications of the incident for the mollusc fishery in general are discussed since these may prove useful to managers of molluscan shellfish producing areas which have not had experience with the toxin. Although an intensive monitoring and inspection programme will allow adequate consumer and producer protection, successful long-term management of the fishery demands a better understanding of the synthesis, distribution and fate of domoic acid, and of molluscan toxins in general.

Patterns of uptake of dissolved amino acids in mussels (Mytilus edulis)

Uptake of dissolved amino acids was measured in mussels adapted to 50% artificial sea water or to the sea water containing 2 mM glycine. In mussels adapted to amino-acid free sea water net uptake from μmolar solutions of glycine, glutamic acid, taurine, glutamine and tyrosine could be described by the Michaelis-Menten equation. Mussels adapted to 2 mM glycine exhibited more complex patterns of uptake that changed with time after transfer to μmolar solutions of glycine. It is suggested that the properties of the epidermal transport systems are adaptable, and that they are modified by the presence of amino acids in the medium, perhaps indirectly through changes in the concentrations of the intracellular pool of free amino acids. The uptake rates measured in mussels adapted to aminoacid free sea water express the maximum capacities for net uptake. In this state of adaptation, mussels that process the surrounding water at optimal rates may clear up to about half of the water passing the mantle cavity of amino acids present at concentrations of about 1 μM. Two thirds of 3H-taurine taken up was recovered in the gills, the remaining third was about equally distributed between the mantle and the rest of the body. There was no significant loss or redistribution of label within 24 h. It is concluded that the uptake of amino acids in the mussel gill is epidermal rather than transepidermal.