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PubMed2003

Bioconcentration and biomagnification of mercury and methylmercury in North Sea and Scheldt estuary fish.

Total Hg and MMHg concentrations were assessed in more than 350 fish and shellfish samples. Hg concentrations in Greater North Sea fish of prey range from 0.039 mg kg(-1) wet weight (ww; for ray) to 0.61 mg kg(-1) ww (for dogfish) and for all other fish species, from 0.045 mg kg(-1) ww (for plaice) to 0.33 mg kg(-1) ww (for sand sole), with 95 +/- 2% of the Hg content in the MMHg form. In Belgian coastal zone, fish concentrations range from 0.063 mg kg(-1) ww for plaice to 0.13 mg kg(-1) ww for flounder, with 82-87% of the Hg content in the MMHg form. In fish of the Scheldt, which is a very polluted estuary, Hg levels, as well as the percent MMHg of the total Hg, were lower than in the two zones previously mentioned. The intraspecies variability is of the order of 50% in each of the three zones. In liver tissue, a much larger variability was observed than in muscle tissue, except for fish species of the Scheldt. In most cases, the MMHg fraction in a particular fish species is inversely related to the intraspecies variability. Bioconcentration and biomagnification factors (BCF and BMF, respectively) were assessed. MMHg-BMFs were a few orders of magnitude higher than Hg(inorganic)-BMFs, and for the same species were always highest in the Greater North Sea and lowest in the Scheldt. For each of the Belgian coastal zone four species, a weak positive correlation between Hg content and fish length was found; however, the larger the size-range, the better the correlation. Taking fish length into account, a statistically significant difference in contamination level was observed for species sampled from the different geographical zones.

Animals↗

PubMed2003

An antifungal chitinase produced by Bacillus cereus with shrimp and crab shell powder as a carbon source.

The production of inexpensive chitinolytic enzymes is an element in the utilization of shellfish processing wastes. In this study, shrimp and crab shell powder prepared by treating shrimp and crab processing wastes with boiling and crushing was used as a substrate for the isolation of an antifungal chitinase-producing microorganism. Bacillus cereus YQ 308, a strain isolated from the soil samples, excreted one chitinase when cultured in a medium containing 2% (wt/vol) shrimp and crab shell powder as major carbon source. The chitinase, purified by sequential chromatography, had an Mr of 48 kDa and pI of 5.2. The purified chitinase (2 mg/ml) inhibited the hyphal extension of the fungi Fusarium oxysporum and Pythium ultimum.

Animals↗

PubMed1986

Oliva vidua fulminans, a marine mollusc, responsible for five fatal cases of neurotoxic food poisoning in Sabah, Malaysia.

This is the first report in which a marine mollusc, Oliva vidua fulminans (olives), generally not known to be poisonous, was responsible for death in five children after consuming boiled olives with tamarind. The onset of symptoms was rapid 10 to 20 min after consumption of the olives. Signs and symptoms included nausea, vomiting, abdominal pain, tingling sensation around the lips, numbness around the mouth, drowsiness, lethargy and generalized weakness with paraesthesia in the limbs. The five deaths occurred within 3 to 4 hours after eating the poisoned olives and resulted from respiratory failure. Left-over olives from the affected household and freshly collected live olives had a toxicity of 14,200 mouse units (M.U.) and 15,000 M.U. per 100 g meat respectively. No other common chemical poison and organophosphorus insecticides were detected. The neurotoxic agent was acid and heat stable and was toxic at pH less than 4. Its action was similar to that of paralytic shellfish poisoning which was caused by toxins from certain dinoflagellates.

Adolescent↗

PubMed1996

A protein phosphatase 2A inhibition assay for a fast and sensitive assessment of okadaic acid contamination in mussels.

The specific inhibitory activity exerted by okadaic acid on protein phosphatase 2A was used to assess the presence of okadaic acid in mussels, using a commercially available protein phosphatase 2A preparation. Under the conditions used, okadaic acid inhibits the enzymatic activity dose-dependently, with an IC50 = 0.26 ng/ml (0.32 nM). The assay is accurate and reproducible. Okadaic acid was detected in concentrations as low as 0.063 ng/ml in aqueous solutions and 2 ng/g in mussel digestive glands. Thirty naturally contaminated mussel samples were submitted to the protein phosphatase 2A inhibition assay as well as to an ELISA assay and to a MTT cytotoxicity assay, with similar results. The proposed assay is sensitive, rapid and does not require expensive equipment. These characteristics make it a good candidate for employment in the routine assessment of okadaic acid shellfish contamination.

Animals↗

PubMed1984

Polychlorinated biphenyls (PCBs) in the marine environment, particularly in the Mediterranean.

Polychlorinated biphenyls (PCBs) possess a low water solubility, a high n-octanol/water partition coefficient, and a high persistence, particularly those which are highly chlorinated. Because of these properties they are bioaccumulated in many organisms in the environment. PCBs are still manufactured industrially and used in the Mediterranean countries (e.g., Italy, Spain, and France). Production figures for these countries and for the FRG, the United Kingdom, and the United States between 1973 and 1979 are given. The concentrations of PCBs in marine air, water, sediments, microplankton , algae, mussels, fish, and other marine organisms including seabirds from the Mediterranean area are reviewed and compared with PCB concentrations in marine samples from non-Mediterranean regions. Levels of PCBs in seawater are highest in the western and central Mediterranean. The data for mussels and fish give a clear indication that the PCB levels are higher in the Northwest and the Tyrrhenian Sea than in the eastern Mediterranean. The FDA in June 1979 set 2 mg/kg as the temporary maximum concentration for PCBs in fish and shellfish. The PCB residues in some fish from the northwestern Mediterranean and Tyrrhenian Sea and in some mussels from the Adriatic Sea are higher than this limit. The amount of PCBs ingested via food by the Mediterranean population is unknown.

Air Pollutants↗

PubMed1993

Distribution of mesophilic Aeromonas species in raw and ready-to-eat fish and meat products in Switzerland.

A total of 829 poultry, meat, shellfish and fish products commonly consumed in Switzerland were qualitatively and quantitatively examined for the presence of mesophilic Aeromonas spp. Overall, aeromonads occurred in 24.1% of the samples. Raw food products were frequently contaminated (e.g. 94.1% in minced meat), with colony counts up to 6.0 x 10(6)/g. Some ready-to-eat products had a relatively high percentage of positive samples as well, such as cooked ham in slices (38.2%), mortadella (12.9%), smoked cooked sausage (15.6%), hot and cold smoked fish (10.9-14.3%) and gravad salmon (10.5%). Colony counts, however, were somewhat lower (up to 1.7 x 10(3)/g). The high contamination rate of cooked or hot smoked foods suggests recontamination after cooking or smoking, e.g., at the slicing and packaging stage. 61.2% of the identified strains were Aeromonas hydrophila, followed by 22.5% Aeromonas caviae and 16.3% Aeromonas sobria.

Aeromonas↗

PubMed2004

A rapid microplate fluorescence method to detect yessotoxins based on their capacity to activate phosphodiesterases.

This paper describes an easy and fast assay with enough sensitivity to detect yessotoxin (YTX) in shellfish samples. YTX decreases intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels by increasing the activity of phosphodiesterases (PDEs). Looking for new methods to detect YTXs, we developed a technique based on this effect. We use the fluorescent derivative of cAMP, anthranyloyl-cAMP, whose fluorescence decreases in time by hydrolysis effect of PDEs. The fluorescence fall is quantified in a plate reader. PDEs induce an anthranyloyl-cAMP hydrolysis rate that is increased in the presence of YTX. This effect is dose dependent, and the representation of YTX concentration versus rate of hydrolysis follows a lineal regression. The measurable range of YTX in this assay is 0.1 to 10microM, while by mouse bioassay, the official method to detect YTXs, the detection limit is 2microM. We determined by this method the concentration of YTX from alcoholic extracts whose concentrations were first determined by high performance liquid chromatography and the variation of concentration was from 5.26microM by fluorescence to 6microM by high performance liquid chromatography and from 3.16 by fluorescence to 3microM by HPLC.

Animals↗

PubMed2006

Analysis of the health risk of exposure to breast milk mercury in infants in Taiwan.

The aim of this study was to assess the total concentration and health risk to infants of breast milk mercury in urban mothers and mothers married to fishermen in relation to fish intake in Taiwan. A total of sixty-eight healthy mothers were recruited for the study. The breast milk mercury geometric mean concentration was 2.02 microgl(-1) (n=56, range: 0.24-9.45 microgl(-1)) for the city group and 2.04 microgl(-1) (n=12, range: 0.26-8.62 microgl(-1)) for the fishermen's group. Of the three sources of mercury exposure (i.e., ingestion (breast milk), inhalation (ambient air), and dermal exposure (shower)), breast-feeding was found to be the largest (96.3-99.6% of the total). From a Monte Carlo simulation, in which methyl mercury accounted for about 50% of total mercury, the hazard quotient (exposure estimate/oral minimal risk level or target organ toxicity dose) exceeded 1.0 for 12.9% of urban babies and 18.8% of fishermen's babies (chronic oral minimal risk level and target organ toxicity dose: 3 x 10(-4)mgkg(-1)d(-1)). The calculated mercury exposure was 3.02 x 10(-1) microgkg(-1)d(-1) for a 3.49 kg urban baby boy and 3.06 x 10(-1) microgkg(-1)d(-1) for a 3.44 kg urban baby girl. These results suggest the life style of mothers (eating raw fish and shellfish such as used in "Sashimi" and "Sushi," and vitamin supplementation) may influence the mercury concentration in breast milk.

Adult↗

PubMed2006

Cryptosporidium and Giardia in commercial and non-commercial oysters (Crassostrea gigas) and water from the Oosterschelde, The Netherlands.

The intestinal parasites Cryptosporidium and Giardia cause gastro-enteritis in humans and can be transmitted via contaminated water. Oysters are filter feeders that have been demonstrated to accumulate pathogens such as Salmonella, Vibrio, norovirus and Cryptosporidium from contaminated water and cause foodborne infections. Oysters are economically important shellfish that are generally consumed raw. Commercial and non-commercial oysters (Crassostrea gigas) and oyster culture water from the Oosterschelde, The Netherlands, were examined for the presence of Cryptosporidium oocysts and Giardia cysts. Nine of 133 (6.7%) oysters from two non-commercial harvesting sites contained Cryptosporidium, Giardia or both. Six of 46 (13.0%) commercial oysters harboured Cryptosporidium or Giardia in their intestines. Data on the viability of (oo)cysts recovered from Oosterschelde oysters were not obtained, however viable (oo)cysts were detected in surface waters that enter the Oosterschelde oyster harvesting areas. The detection of Cryptosporidium and Giardia in oysters destined for human consumption has implications for public health only when human pathogenic (oo)cysts that have preserved infectivity during their stay in a marine environment are present. Our data suggest that consumption of raw oysters from the Oosterschelde may occasionally lead to cases of gastro-intestinal illness.

Animals↗

PubMed2004

Gas-phase dissociation reactions of protonated saxitoxin and neosaxitoxin.

The aim of this study was to investigate the behavior of the protonated paralytic shellfish poisons saxitoxin (STX) and neosaxitoxin (NEO) in the gas-phase after ion activation using different tandem mass spectrometry techniques. STX and NEO belong to a group of neurotoxins produced by several strains of marine dinoflagellates. Their chemical structures are based on a tetrahydropurine skeleton to which a 5-membered ring is fused. STX and NEO only vary in their substituent at N-1, with STX carrying hydrogen and NEO having a hydroxyl group at this position. The collision-induced dissociation (CID) spectra exhibited an unusually rich variety and abundance of species due to the large number of functional groups within the small skeletal structures. Starting with triple-quadrupole CID spectra as templates, linked ion-trap MSn data were added to provide tentative dissociation schemes. Subsequent high-resolution FTICR experiments gave exact mass data for product ions formed via infrared multiphoton dissociation (IRMPD) from which elemental formulas were derived. Calculations of proton affinities of STX and NEO suggested that protonation took place at the guanidinium group in the pyrimidine ring for both molecules. Most of the observed parallel and consecutive fragmentations could be rationalized through neutral losses of H2O, NH3, CO, CO2, CH2O and different isocyanate, ketenimine and diimine species, many of which were similar for STX and NEO. Several exceptions, however, were noted and differences could be readily correlated with reactions involving NEO's additional hydroxyl group. A few interesting variations between CID and IRMPD spectra are also highlighted in this paper.

Animals↗

PubMed2006

Tidal transport and dispersal of marine toxic microalgae in a shallow, temperate coastal lagoon.

A numerical model was used to predict toxic microalgal transport and dispersion in Ria de Aveiro in Portugal. A previously developed Lagrangean particle tracking model coupled to a calibrated two-dimensional hydrodynamic model of Ria de Aveiro was used. Microalgae were regarded as passive particles and the methodology used allowed the determination of their trajectories, as induced by the tidal currents predicted by the hydrodynamic model. The model assumes Ria de Aveiro as vertically homogeneous and does not take into account the vertical distribution patterns of microalgae. Simulations were carried out during extreme spring and neap tides, with microalgal released at the mouth of the lagoon at the local flood. The maximum and minimum areas affected during the occurrence of toxic microalgal blooms were estimated to evaluate the suitability of the distribution of the sampling stations included in the local monitoring program. It was found that the tidal currents greatly determine the microalgal horizontal distribution and dispersal in the lagoon. The results confirmed that the locations of water and bivalve shellfish sampling stations, postulated by INIAP/IPIMAR, in the context of the local harmful algal bloom (HAB) program, were appropriate, although some possible refinements were identified.

Animals↗

PubMed2004

Zoonotic protozoa: from land to sea.

Attention to worldwide pollution of the coastal marine environment has focused primarily on toxic algal blooms and pathogenic bacteria that multiply in nutrient-rich waters. However, massive but unseen amounts of feces from humans, their pets, and their domesticated animals are discharged, dumped, or carried in runoff, bringing encysted zoonotic protozoan parasites to estuaries and coastal waters. Here, they contaminate bathing beaches, are filtered and concentrated by shellfish eaten by humans and marine mammals, and infect a wide range of marine animal hosts, resulting in morbidity and mortality to some populations. This review addresses the extent of contamination and the animals affected by three genera of important zoonotic protozoa: Giardia, Cryptosporidium and Toxoplasma.

Animals↗

PubMed2004

Variety of PSP toxins in four culture strains of Alexandrium minutum collected from southern Taiwan.

Paralytic shellfish poisoning (PSP) toxin profiles were compared among four culture strains of Alexandrium minutum. GTX-1, 2, 3 and 4 are the PSP toxins that occur in A. minutum, and other PSP toxins were not detected. When comparing the toxin profile of four A. minutum strains, GTX1 and 4 were the major toxins in Amtk1, Amtk2, and Amtk4, but in Amtk7, GTX3 and 2 were the major toxins. The results indicate that strains with various toxin profiles exist in southern Taiwan, and suggest that the comparison of the toxin profiles between strains at different localities is difficult. Additionally, the toxin profiles of A. minutum strains cultured in the same environment were different, suggesting that it was owing to the intrinsic nature of toxic algae.

Animals↗

PubMed2004

Analysis of PSP toxins in Norwegian mussels by a post-column derivatization HPLC method.

The aim of this study was to investigate the agreement between the AOAC mouse bioassay and an HPLC method for determining Paralytic Shellfish Poisoning (PSP) toxicity in blue mussels from the Norwegian coast. The AOAC mouse bioassay has traditionally been used for determining the toxin levels. Recently, an HPLC method for determining PSP toxins has been implemented and run in parallel with the bioassay. Four hundred mussel extracts from the last six years were analysed with both methods. A highly significant linear correlation between the methods was achieved (r = 0.84). However, the relation between the two methods was best described by a second-degree polynom. Totally, this model explained 87% of the variation in the HPLC method. By agreement analysis, it was possible to establish cut-off levels for the HPLC method related to the AOAC mouse bioassay with kappa values >0.80 for toxicity levels below 500 MU/100 g. The HPLC method could substitute the mouse bioassay in determining PSP toxicity in Norwegian mussels. Additionally, about 70 mussel samples were also analysed by the MIST Alert trade mark test kit. The kit did not give any false negative results compared with the regulatory limit, but 30% of the samples below the cut point were also determined as positive.

Animals↗

PubMed2006

Relative toxicity of dinophysistoxin-2 (DTX-2) compared with okadaic acid, based on acute intraperitoneal toxicity in mice.

When substituting the mouse bioassay for lipophilic marine algal toxins in shellfish with analytical methods, science based factors of relative toxicity for all analogues that contribute to health risk to consumers are necessary. The aim of this paper is to establish the relative intraperitoneal toxicity of dinophysistoxin-2 (DTX-2) compared with okadaic acid (OA). The study was performed as an open, randomised parallel group trial with a four level response surface design within each of the two parallels. In accordance with the response surface design model, the LD50 for DTX-2 and OA was 338 and 206 microg/kg, respectively. By use of common regression analysis, the LD50 of DTX-2 and OA were estimated to 352 microg/kg and 204 microg/kg, respectively. The deviations between the LD50 estimates by the two methods was 4% for DTX-2 and less than 1% for OA. Taken together, these results indicate that the relative toxicity of DTX-2 is about 0.6, compared to OA. Results from the PP2A assay correspond very well with the results obtained by the mouse bioassay. The IC50 concentrations for DTX-2 and OA were 5.94 and 2.81 ng/mL, respectively. This indicates that OA is about twice as toxic as DTX-2. Since inhibition of PP2A is acknowledged as the main mechanism of toxicity of the OA group toxins, this supports the establishment of a relative toxicity factor of DTX-2 of 0.6 compared with OA.

Animals↗

PubMed2006

A slot blot procedure for the measurement of yessotoxins by a functional assay.

We originally developed a functional assay for the detection of yessotoxins (YTX) based on its capacity to induce dose-dependent changes in cellular levels of two marker proteins, consisting of E-cadherin and an E-cadherin fragment (ECRA100) in epithelial cells. The procedure is time-consuming and we have shortened it by a slot blot format, using antibodies recognizing two different epitopes of E-cadherin (HECD-1 and C20820), thereby discriminating those markers. The best performing membrane under our conditions, in terms of binding capacity and even absorption of proteins, was a positively charged nylon membrane. Treatment of the membrane with 0.5mug of Ab/ml was appropriate for maximal detection of antigens by our slot blot procedure with both HECD-1 and C20820 antibodies. The treatment of cells with YTX, resulting in a relative increase in the cellular levels of ECRA100, led to a dose-dependent increase of the signal detected by Ab HECD-1 without a concomitant increase in the signal detected by Ab C20820 in our slot blot format, and the concentrations of YTX were correlated to both the increase of the signal detected through Ab HECD-1 and to the decrease in the ratio of the signals obtained with the two Abs (C20820 over HECD-1). Upon analyses of extracts from cells treated with shellfish samples, we could detect and quantify YTX in naturally contaminated materials. The slot blot format of our functional assay allows a substantial shortening of its analytical step (about seven hr, as compared to the two working days of the original method), providing YTX measurements that are accurate but show large standard deviations.

Animals↗

PubMed2006

Application of precolumn oxidation HPLC method with fluorescence detection to evaluate saxitoxin levels in discrete brain regions of rats.

Saxitoxin (STX) is one of several related toxins that cause paralytic shellfish poisoning (PSP). This toxin blocks neuronal transmission by binding to the voltage-gated Na+ channel and for this reason, it has been widely used in the study of Na+ channel. The aim of this study was to analyze STX distribution in different rat brain regions after its acute intraperitoneal (i.p.) administration. Male rats (150-200 g) were injected i.p. with STX (5 and 10 microg/kg of body weight). After three time intervals of 30, 60, and 120 min (for 5 microg/kg STX dose) and 30 min (for 10 microg/kg STX dose) animals were sacrificed by cervical dislocation. Brains were removed and dissected in seven regions. STX concentration was measured using a precolumn oxidation high-performance liquid chromatographic method with fluorescence detection (HPLC/FLD). STX was found in all the regions evaluated at ppm levels meaning that STX peripherical administered across the blood-brain barrier and is distributed along the whole brain.

Animals↗

PubMed2001

Trace element studies in Laucala Bay, Suva, Fiji.

The trace metal distribution in the sediments of Laucala Bay, a coastal lagoon with a barrier reef and significant freshwater input, adjacent to Suva, the capital of Fiji (150,000 people), was studied from the point of view of assessing the significance of anthropogenic sources relative to natural ones. Surface sediments from 25 sites in the Bay were analysed for particle size distribution, organic carbon and major (Si, Al, Fe, Ca, Mg) and trace metal (Mn, Zn, Cu, Pb, Cd, Hg) contents. Suspended sediments from one site and shellfish samples from five sites were also analysed. The sediments were found to be mostly of terrigenous origin. Particle size distribution, organic carbon and major elemental composition of the sediments were generally related to location within the Bay. A significant natural source of trace metals in the sediments is the suspended solids transported into the Bay by rivers. The spatial distribution of trace metals could not be fully explained by the particle size distribution and mineral composition of the sediments. Contributions from anthropogenic sources were also suspected, but the degree of enrichment from such sources is not great at the present time.

Animals↗