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At least 1,621 records · Page 90Linked to original sources

PubMed2005

Estimation of the dietary intake of cadmium, lead, mercury, and arsenic by the population of Santiago (Chile) using a Total Diet Study.

Dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) by the population of Santiago (Chile) was determined using a Total Diet Study in the market basket modality. After conducting a survey of the foods consumed in the last 24 h, the most consumed food products were included in the basket. Subsequently, they were cooked or prepared according to typical Chilean procedures and grouped into 17 food categories according to their chemical characteristics. The fish and shellfish group had the highest contents of As (1351 ng/g wet weight, ww), Cd (277 ng/g ww), and Hg (48 ng/g ww), while the sugar group had the highest content of Pb (251 ng/g ww). For a person with a body weight of 68 kg, the dietary intakes of As (77 microg/day), Cd (20 microg/day), Hg (5 microg/day), and Pb (206 microg/day) are lower than the provisional tolerable weekly intake values established by the FAO/WHO. Consequently, the total intakes of As, Cd, Hg, and Pb in Santiago (Chile) are within the limits estimated as safe.

Arsenic↗

PubMed2004

Investigation of clonal distribution and persistence of Salmonella Senftenberg in the marine environment and identification of potential sources of contamination.

Salmonella Senftenberg was detected in the coastal areas of Galicia (NW Spain) in 1998, where it remained the predominant serovar for the next four years. Although the overall incidence of this serovar in the zone was lower than 1%, contamination by Salmonella serovar Senftenberg was located in very specific areas of the Ría de Arousa, where it persisted for more than five years. A total of 60 Salmonella serovar Senftenberg isolates, originating from surveillance activities in marine environments, was subjected to molecular characterization by pulsed-field gel electrophoresis (PFGE). PFGE analysis of the marine isolates allowed the differentiation of three main PFGE types, which contained the majority of the isolates, each type showing a specific spatial distribution in the coastal waters. The most prevalent pulse types persisted for more than four years, emphasizing their capacity to adapt and survive in marine environments. Using PFGE analysis, marine isolates were compared with Salmonella serovar Senftenberg isolates from neighbouring mussel-processing facilities and to other epidemiologically unrelated isolates from human, animal and feed sources. Comparison of the restriction patterns showed that indistinguishable PFGE types were present in the isolates from mussel-processing facilities and their surrounding marine areas, suggesting that the mussel processing is the main source for contamination with Salmonella Senftenberg in these marine environments. A molecular fingerprinting relationship was established between three shellfish isolates and a human isolate, which could be considered as preliminary evidence of infection caused by Salmonella Senftenberg associated with molluscan consumption.

Animals↗

PubMed2004

Regulation of proinflammatory mediator production in RAW264.7 macrophage by Vibrio vulnificus luxS and smcR.

Vibrio vulnificus causes fatal septicemia in human hosts, which is the consequence of raw shellfish consumption. The mortality following septicemia is dependent on the in vivo production of inflammatory mediators, including tumor necrosis factor-alpha (TNFalpha). The present study was set up to investigate the association of quorum sensing in V. vulnificus with the host immune response. The effect of quorum sensing on cytotoxicity and the production of proinflammatory mediators was examined using the murine macrophage cell-line RAW264.7. Cytotoxicity was determined by measuring lactate dehydrogenase release in the culture medium. Extracellular products from luxS- and smcR-deficient mutants exhibited weak cytotoxic effects on RAW264.7 cells. The production of the proinflammatory cytokines TNFalpha, IL-1beta and IL-6 was measured with real-time PCR and ELISA, and production was measured with Griess reagents. Mutation of both luxS and smcR delayed the transcription of TNFalpha, IL-1beta and IL-6 genes. Also, levels of both TNFalpha and nitric oxide induced by luxS- and smcR-deficient mutants were significantly lower than those induced by parent strains. These results suggest that quorum sensing could be involved in the modulation of TNFalpha and nitric oxide produced from host cells by regulating virulence factors, and that V. vulnificus facilitates its host's mortality and bacterial survival by enhancing virulence on host cells.

Animals↗

PubMed2005

Identification of a gene induced in conjugation-promoted cells of toxic marine dinoflagellates Alexandrium tamarense and Alexandrium catenella using differential display analysis.

Marine dinoflagellates Alexandrium tamarense and Alexandrium catenella produce toxins that cause paralytic shellfish poisoning (PSP). A detailed mechanism of encystment is necessary for a better understanding of bloom dynamics and the toxic effect of these organisms. In this study, a cDNA that was up-regulated in conjugation-promoted cells at encystment was identified using differential display. It encoded a polypeptide of 195 amino acids with a molecular weight of 20,900 Da. The deduced amino acid sequence of this cDNA showed 62% similarity with the polypeptide encoded by SPS19, a gene that is activated specifically during spore maturation and spore wall formation in Saccharomyces cerevisiae. Therefore, the cDNA obtained was termed an SPS19 homolog in this study. The expression levels of the SPS19 homolog were highest immediately after the promotion of conjugation and decreased sequentially later, a pattern similar to that of SPS19 in the sporulation of S. cerevisiae in terms of the time of induction and the duration of expression. These similarities between the SPS19 homolog and SPS19 suggested that the putative function of the SPS19 homolog might be an involvement in encystment. RT-PCR showed that the expression of the SPS19 homolog was highest in conjugation-promoted cells but low in vegetative cells. The SPS19 homolog was believed to be expressed constantly in order for cells to respond rapidly to environmental changes and ensure encystment. Characterization of the identified gene might help in understanding the mechanism of encystment.

Amino Acid Sequence↗

PubMed2004

In vitro effects of cadmium and mercury on Pacific oyster, Crassostrea gigas (Thunberg), haemocytes.

In the past decades, shellfish culture has developed in a significant way around the world. However, culture areas are often subject to recurring anthropic pollution. The recrudescent presence of industrial wastes is a source of heavy metals and results in pollutant transfer towards the aquatic environment in estuarine areas. Because of their mode of life, bivalves, including mussels and oysters, are suggested as ideal indicator organisms. The development of techniques allowing the analysis of the effects of pollutants on bivalve biology may lead to the monitoring of pollutant transfer in estuarine areas. In this context, the effects of cadmium and mercury on defence mechanisms were analysed in Pacific oysters, Crassostrea gigas. Pollutant effects were tested in vitro on oyster haemocytes. Cell viability and enzymatic activities (esterase, peroxidase, aminopeptidase, phagocytosis activities) were monitored by flow cytometry. Enzymatic phenoloxidase-like activity was also evaluated by spectrophotometry. High pollutant concentrations were used in order to detect the acute effect and to approach real pollutant concentrations existing in animal tissues. Cadmium induced no effect on oyster haemocytes under the tested conditions. On the contrary, mercury caused a significant haemocyte mortality after a 24 h in vitro incubation. Aminopeptidase positive cell percentage was enhanced by the pollutant, and phenoloxidase-like activity was inhibited. These in vitro results show that mercury may be expected to have an impact on bivalve immune functions in contaminated areas.

Aminopeptidases↗

PubMed2006

Inhibitory kinetics of phenol on the enzyme activity of beta-N-acetyl-D-glucosaminidase from green crab (Scylla serrata).

Chemical pollution such as chromium and phenol in the sea water has been increasing in recent years in China sea. At the same time, marine shellfish such as prawn and crab are sensitive to this pollution. beta-N-acetyl-D-glucosaminidase (NAGase, EC.3.2.1.52) catalyzes the cleavage the oligomers of N-acetylglucosamine (NAG) into the monomer. In this paper, the effects of phenol on the enzyme activity from green crab (Scylla serrata) for the hydrolysis of p-nitrophenyl-N-acetyl-beta-D-glucosaminide (pNP-NAG) have been studied. The results showed that appropriate concentrations of phenol could lead to reversible inhibition on the enzyme and the inhibitor concentration leading to 50% activity lost, IC(50), was estimated to be 75.0+/-2.0 mM. The inhibitory kinetics of phenol on the enzyme in the appropriate concentrations of phenol has been studied using the kinetic method of substrate reaction. The time course of the enzyme for the hydrolysis of pNP-NAG in the presence of different concentrations of phenol showed that at each phenol concentration, the rate decreased with increasing time until a straight line was approached. The results show that the inhibition of the enzyme by phenol is a slow, reversible reaction with fractional remaining activity. The microscopic rate constants are determined for the reaction on phenol with the enzyme.

Acetylglucosaminidase↗

PubMed2004

Occurrence of Campylobacter in retail foods in Ireland.

A surveillance study was carried out to determine the prevalence of Campylobacter in a range of retail foods purchased in three Irish cities over a 20-month period between March 2001 and October 2002. In total 2391 food samples were analysed during this period. Campylobacter was isolated from 444 raw chicken (49.9%), 33 turkey (37.5%) and 11 duck samples (45.8%). Lower isolation rates of 7/221 (3.2%), 10/197 (5.1%) and 31/262 (11.8%) were observed for raw beef, pork and lamb, respectively. One sample of pork paté from 120 samples analysed (0.8%) was Campylobacter-positive. A total of three shellfish samples (oysters) from 129 raw specimens examined (2.3%) were found to contain Campylobacter. Low prevalences of the organism (0.9%) were also isolated from fresh mushrooms. Of 62 raw bulk tank milk samples analysed, Campylobacter was recovered in a single sample (1.6%). Campylobacter was not detected in any of the comminuted pork puddings, prepared vegetables and salads, retail sandwiches or cheeses made from unpasteurised milk. In total, 543 Campylobacter were isolated from all of the food samples analysed, of which 453 (83.4%) were confirmed as Campylobacter jejuni and the remaining 90 (16.6%) as Campylobacter coli.

Agaricales↗

PubMed2006

Cryptosporidium oocysts in mussels (Mytilus edulis) from Normandy (France).

Cultured mussels (Mytilus edulis) were collected seasonally during one year from three sites on the Northwestern coastal area of Normandy (France). Flesh, gills and innerwater were examined for Cryptosporidium oocyst detection using immunomagnetic separation and immunofluorescence assay. Oocysts were present in all samples for all sites and seasons and flesh was the most contaminated part. Oocyst rates were apparently related with seasonal rain precipitation variations. Molecular analysis revealed that oocysts belonged to the species Cryptosporidium parvum (formerly genotype 2 or < >). Oocyst infectivity was assessed by oral administration to suckling NMRI-mice, and developmental stages were observed in only one mouse infected with oocysts from one location. The detection of potentially infectious C. parvum oocysts of likely cattle-breeding origin in cultured edible mussels confirms their resistance to sea environments, and underlines the potential risk of food-borne infection. This work reports for the first time the presence of infectious Cryptosporidium oocysts in shellfish from France.

Animals↗

PubMed2005

New genotypes and factors associated with Cryptosporidium detection in mussels (Mytilus spp.) along the California coast.

A 3 year study was conducted to evaluate mussels as bioindicators of faecal contamination in coastal ecosystems of California. Haemolymph samples from 4680 mussels (Mytilus spp.) were tested for Cryptosporidium genotypes using PCR amplification and DNA sequence analysis. Our hypotheses were that mussels collected from sites near livestock runoff or human sewage outflow would be more likely to contain the faecal pathogen Cryptosporidium than mussels collected distant to these sites, and that the prevalence would be greatest during the wet season when runoff into the nearshore marine environment was highest. To test these hypotheses, 156 batches of sentinel mussels were collected quarterly at nearshore marine sites considered at higher risk for exposure to livestock runoff, higher risk for exposure to human sewage, or lower risk for exposure to both faecal sources. Cryptosporidium genotypes detected in Haemolymph samples from individual mussels included Cryptosporidium parvum, Cryptosporidium felis, Cryptosporidium andersoni, and two novel Cryptosporidium spp. Factors significantly associated with detection of Cryptosporidium spp. in mussel batches were exposure to freshwater outflow and mussel collection within a week following a precipitation event. Detection of Cryptosporidium spp. was not associated with higher or lower risk status for exposure to livestock faeces or human sewage sources. This study showed that mussels can be used to monitor water quality in California and suggests that humans and animals ingesting faecal-contaminated water and shellfish may be exposed to both host-specific and anthropozoonotic Cryptosporidium genotypes of public health significance.

Animals↗

PubMed2006

9. Food allergy.

Food allergy, defined as an adverse immune response to food proteins, affects as many as 6% of young children and 3% to 4% of adults. Food-induced allergic reactions are responsible for a variety of symptoms involving the skin, gastrointestinal tract, and respiratory tract and might be caused by IgE-mediated and non-IgE-mediated (cellular) mechanisms. Our understanding of how food allergy represents an abrogation of normal oral tolerance is evolving. Although any food can provoke a reaction, relatively few foods are responsible for the vast majority of significant food-induced allergic reactions: milk, egg, peanuts, tree nuts, fish, and shellfish. A systematic approach to diagnosis includes a careful history, followed by laboratory studies, elimination diets, and often food challenges to confirm a diagnosis. Many food allergens have been characterized at a molecular level, which has increased our understanding of the immunopathogenesis of food allergy and might soon lead to novel diagnostic and therapeutic approaches. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and to initiate therapy in case of an unintended ingestion.

Adult↗

PubMed2005

Assigning product ions from complex MS/MS spectra: the importance of mass uncertainty and resolving power.

This study offers a unique insight into the mass accuracy and resolving power requirements in MS/MS analyses of complex product ion spectra. In the examples presented here, accurate mass assignments were often difficult because of multiple isobaric interferences and centroid mass shifts. The question then arose whether the resolving power of a medium-resolution quadrupole time-of flight (QqTOF) is sufficient or high-resolution Fourier-transform ion cyclotron resonance (FT-ICR) is required for unambiguous assignments of elemental compositions. For the comparison, two paralytic shellfish poisons (PSP), saxitoxin (STX) and neosaxitoxin (NEO), with molecular weights of 299 and 315 g x mol(-1), respectively, were chosen because of the high peak density in their MS/MS spectra. The assessment of QqTOF collision-induced dissociation spectra and FT-ICR infrared multiphoton dissociation spectra revealed that several intrinsic dissociation pathways leading to isobaric fragment ions could not be resolved with the QqTOF instrument and required FT-ICR to distinguish very close mass differences. The second major source of interferences was M + 1 species originating from coactivated 13C12Cc-1 ion contributions of the protonated molecules of the PSPs. The problem in QqTOF MS results from internal mass calibration when the MH+ ions of analyte and mass calibrant are activated at the same time in the collision or trapping cell. Although FT-ICR MS readily resolved these interfering species, the QqTOF did not provide resolving power >20,000 (full width at half maximum) required to separate most isobaric species. We were able to develop a semi-internal QqTOF calibration technique that activated only the isolated 12C isotope species of the protonated molecules, thus reducing the M + 1 interferences significantly. In terms of overall automated elemental formulas assignment, FT-ICR MS achieved the first formula hit for 100% of the product ions, whereas the QqTOF MS hit rate was only 56 and 65% for STX and NEO product ions, respectively. External mass calibration from commercial FT-ICR and QqTOF instruments gave similar results.

Calibration↗

PubMed2006

Fuzzy rule-based modelling for human health risk from naturally occurring radioactive materials in produced water.

Produced water, discharged from offshore oil and gas operations, contains chemicals from formation water, condensed water, and any chemical added down hole or during the oil/water separation process. Although, most of the contaminants fall below the detection limits within a short distance from the discharge port, a few of the remaining contaminants including naturally occurring radioactive materials (NORM) are of concern due to their bioavailability in the media and bioaccumulation characteristics in finfish and shellfish species used for human consumption. In the past, several initiatives have been taken to model human health risk from NORM in produced water. The parameters of the available risk assessment models are imprecise and sparse in nature. In this study, a fuzzy possibilistic evaluation using fuzzy rule based modeling has been presented. Being conservative in nature, the possibilistic approach considers possible input parameter values; thus provides better environmental prediction than the Monte Carlo (MC) calculation. The uncertainties of the input parameters were captured with fuzzy triangular membership functions (TFNs). Fuzzy if-then rules were applied for input concentrations of two isotopes of radium, namely (226)Ra, and (228)Ra, available in produced water and bulk dilution to evaluate the radium concentration in fish tissue used for human consumption. The bulk dilution was predicted using four input parameters: produced water discharge rate, ambient seawater velocity, depth of discharge port and density gradient. The evaluated cancer risk shows compliance with the regulatory guidelines; thus minimum risk to human health is expected from NORM components in produced water.

Background Radiation↗

PubMed2005

Sensitivity of a digoxigenin-labelled DNA probe in detecting Mikrocytos mackini, causative agent of Denman Island disease (mikrocytosis), in oysters.

The protistan parasite Mikrocytos mackini, causative agent of Denman Island disease (mikrocytosis), induces mortality and reduces marketability in the Pacific oyster, Crassostrea gigas, in British Columbia, Canada. This parasite is a pathogen of international concern because it infects a range of oyster species, and because its life cycle and mode of transmission are unknown. A digoxigenin-labelled DNA probe in situ hybridisation technique (DIG-ISH) was developed, and its detection sensitivity was compared to standard histological sections stained with haematoxylin and eosin stain (H&E-histo). In H&E-histo preparations, the detection of M. mackini was certain only when the parasite occurred within the vesicular connective tissue of adult oysters. However, the DIG-ISH technique clearly demonstrated the presence of infection in all other host tissues as well as in juvenile oysters with poorly developed vesicular connective tissue. The probe hybridised strongly to M. mackini, did not hybridise to oyster tissues or with the other shellfish parasites tested, and was more sensitive for detecting infections when compared to H&E-histo.

Animals↗

PubMed2004

Use of reverse transcription and PCR to discriminate between infectious and non-infectious hepatitis A virus.

Hepatitis A virus (HAV) is a major cause of infectious hepatitis worldwide. Detection of HAV in contaminated food or water is a priority research area in laboratories worldwide. Our laboratory has reported previously the development of reverse transcription-polymerase chain reaction (RT-PCR) based detection and typing methods for HAV in contaminated shellfish and produce. It is commonly held that RT-PCR can detect viral genome, but cannot distinguish between infectious and inactivated virus. Therefore, signals obtained after PCR should be considered as false positives unless it can be shown that the sample contains virus capable of infecting a suitable host cell line in culture. We present data to show that this general assumption is not valid. Evidence is provided that demonstrate that signals generated after RT-PCR amplification of viral genome correlated well with the presence of infectious virus in the sample. Viral samples inactivated by heat or UV treatment produced significantly lower signal strength that paralleled infectivity of the sample in cultured cells. The loss of signal strength is most likely the result of damage to the viral RNA that renders it unsuitable for RT-PCR. The correlation between PCR signal and infectivity was better following UV inactivation than heat treatment. The procedure may be adapted to other viruses and inactivating agents.

Base Sequence↗

PubMed2004

Anthropogenic regulation of the phosphorus balance in the Thau catchment-coastal lagoon system (Mediterraean Sea, France) over 24 years.

In the Thau lagoon, despite there being no phosphate limitation policy, the annual mean phosphate concentrations decreased by 90% between 1971 and 1994. The present study indicates a relationship between the decrease of phosphate concentrations and changes in urban, industrial and agricultural activities within the catchment generating phosphorus (P) inputs; and shellfish farming leading to phosphorus storage and export. The relationship (tonnes of P) is: P-PO(4)(3-) in the lagoon waters=1.0124 anthropogenic phosphorus balance--47.62 (r(2) = 0.824, p < 0.000). As population growth is expected in coastal zones, sustainable development requires the need for addressing the role played by human activities and the multi-scale regulation of them. As an element of integrated coastal zone management, the present study provides a regional scale analysis of these aspects.

Agrochemicals↗

PubMed2004

PSP-toxicification of the carnivorous gastropod Rapana venosa inhabiting the estuary of Nikoh River, Hiroshima Bay, Hiroshima Prefecture, Japan.

During surveillance on the toxicity of invertebrates such as bivalves inhabiting the coasts of Hiroshima Bay in 2001 and 2002, the carnivorous gastropod rapa whelk Rapana venosa collected in the estuary of Nikoh River, was found to contain toxins which showed paralytic actions in mice; the maximum toxicities (as paralytic shellfish poison, PSP) were 4.2 MU/g (May 2001) and 11.4 MU/g (April 2002). Their total toxicities were 224 and 206 MU/viscera of one specimen throughout the monitoring period. Attempts were made to identify the toxic principle in the gastropod. The viscera were extracted with 80% ethanol acidified with acetic acid, followed by defatting with dichloromethane. The aqueous layer obtained was treated with activated charcoal and then applied to a Sep-Pak C18 cartridge. The unbound toxic fraction was analyzed by high-performance liquid chromatography techniques. The gastropod toxin was rather unexpectedly identified as PSP. It was comprised of high toxic component (gonyautoxin-3; GTX3, GTX2, saxitoxin; STX) as the major components, which accounted for approximately 91 mol% of all components along with C1 and C2, which are N-sulfocarbamoyl derivatives. Judging from their toxin patterns, it is suggested that the PSP toxification mechanism of the gastropod that PSP toxins produced by phytoplankton such as Alexandrium tamarense, are transferred to and accumulated in plankton feeders such as the short-necked clam, and then transferred to this carnivorous rapa whelk R. venosa through predation.

Animals↗

PubMed2004

Monitoring chemical contamination levels in the Mediterranean based on the use of mussel caging.

Within the framework of the biointegrator network (RINBIO), 92 man-made cages containing mussels (Mytilus galloprovincialis), distributed over 1800 km of the French Mediterranean coast, made it possible to assess chemical contamination by heavy metals (Cd, Hg, Zn, Pb, Cu, Ni, Cr, As) and organic compounds (DDT, PCBs, HAP). The caging technique was adopted to compensate for the scarcity of natural shellfish stocks in the Mediterranean and to enable comparison of the sites regardless of their physicochemical and trophic characteristics. Models linking a biometric parameter (the condition index) to pollutant levels make it possible to adjust raw data on contamination for a reference individual, by making a clear distinction between physiological factors (growth) and environmental ones. The results demonstrate significant levels of pollutants in sites heretofore unsampled; the pollution occurs at limited areas, and the sources have been identified. Moreover, average contamination levels are comparable to those measured in wild species and in other areas. Overall, the research demonstrates the reliability of this methodological approach for monitoring marine pollution, especially in the Mediterranean.

Animals↗

PubMed2005

Microbial modulation in the biomass and toxin production of a red-tide causing alga.

The effect of S10, a strain of marine bacteria isolated from sediment in the Western Xiamen Sea, on the growth and paralytic shellfish poison (PSP) production in the alga Alexandrium tamarense (A. tamarense) was studied under controlled experimental conditions. The results of these experiments have shown that the growth of A. tamarense is obviously inhibited by S10 at high concentrations, however no evident effect on its growth was observed at low concentrations. Its PSP production was also inhibited by S10 at different concentrations, especially at low concentrations. The toxicity of this strain of A. tamarense is about (0.95-12.14) x 10(-6) MU/cell, a peak toxicity value of 12.14 x 10(-6) MU/cell appeared on the 14th day, after which levels decreased gradually. The alga grew well in conditions of pH 6-8 and salinities of 20-34 per thousand. The toxicity of the alga varied markedly at different pH and salinity levels. Toxicity decreased as pH increased, while it increased with salinity and reached a peak value at a salinity of 30 per thousand, after which it declined gradually. S10 at a concentration of 1.02 x 10(9) cells/ml inhibited growth and the PSP production of A. tamarense at different pH and salinity levels. S10 had the strongest inhibitory function on the growth of A. tamarense under conditions of pH 7 and a salinity of 34 per thousand. The best inhibitory effect on PSP production by A. tamarense was at pH 7, this inhibitory effect on PSP production did not relate to salinity. Interactions between marine bacteria and A. tamarense were also investigated using the flow cytometer technique (FCM) as well as direct microscope counting. S10 was identified as being a member of the genus Bacillus, the difference in 16S rDNA between S10 and Bacillus halmapalus was only 2%. The mechanism involved in the inhibition of growth and PSP production of A. tamarense by this strain of marine bacteria, and the prospect of using it and other marine bacteria in the bio-control of red-tides was discussed.

Animals↗