Sensitive determination of domoic acid using high-performance liquid chromatography with electrogenerated tris(2,2'-bipyridine)ruthenium(III) chemiluminescence detection.
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A new sensitive determination method of domoic acid based on the chemiluminescent reaction of tris(2,2'-bipyridine)ruthenium(III) has been developed. The method exhibited good reproducibility. The relative standard deviation of six replicate measurements was 1.6% for 10 ng ml(-1). A calibration graph, based on a standard domoic acid solution, was linear over the range of 1 - 500 ng ml(-1) (coefficient of correlation, r2 = 0.9995) and the detection limit was 8 pg (signal-to-noise ratio = 3) without any preconcentration and derivatization steps. This new method was successfully applied to a real sample of blue mussels spiked with 2 microg g(-1) domoic acid. (+info)
Fishing down the coast: historical expansion and collapse of oyster fisheries along continental margins.
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Estuarine ecosystems have changed dramatically from centuries of fishing, habitat disturbance, sedimentation, and nutrient loading. Degradation of oyster reefs by destructive fishing practices in particular has had a profound effect on estuarine ecology, yet the timing and magnitude of oyster-reef degradation in estuaries is poorly quantified. Here, I evaluate the expansion and collapse of oyster fisheries in 28 estuaries along three continental margins through the analysis of historical proxies derived from fishery records to infer when oyster reefs were degraded. Exploitation for oysters did not occur randomly along continental margins but followed a predictable pattern. Oyster fisheries expanded and collapsed in a linear sequence along eastern North America (Crassostrea virginica), western North America (Ostreola conchaphila), and eastern Australia (Saccostrea glomerata). Fishery collapse began in the estuaries that were nearest to a developing urban center before exploitation began to spread down the coast. As each successive fishery collapsed, oysters from more distant estuaries were fished and transported to restock exploited estuaries near the original urban center. This moving wave of exploitation traveled along each coastline until the most distant estuary had been reached and overfished. (+info)
Vibrio spp. and Salmonella spp., presence and susceptibility in crabs Ucides cordatus.
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The presence of Vibrio spp. and Salmonella spp. in crabs marketed at the Bezerra de Menezes Ave., Fortaleza, State of Ceara, Brazil, was assessed between February and May, 2003. The number of individuals sampled in each one of the fifteen weekly samplings ranged between four and eight. Seven strains of Salmonella, from four different samplings, were identified, being five of them identified as serotype S. Senftenberg and two as S. Poona. All strains of Salmonella were sensitive to the tested anti-microbial drugs, with the exception of tetracycline and nalidixic acid, for which an intermediary sensibility was found. The MPN's for Vibrio ranged between 110/g and 110,000/g. Of the forty five Vibrio strains isolated from the crab samples, only 10 were identified up to the species level: two V. alginolyticus and eight V. parahaemolyticus. Bacteria belonging to the Enterobacteriaceae and Pseudomonaceae families were also identified, namely Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pantoea agglomerans and Pseudomonas aeruginosa. The proper cooking of the animals is recommended in order to avoid problems for the consumers of this crustacean. (+info)
Reverse transcription-booster PCR for detection of noroviruses in shellfish.
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The methods commonly used for norovirus (NV) detection are based on reverse transcription-PCR (RT-PCR) followed by confirmation of the amplified sequence. To increase sensitivity, an RT-booster PCR was developed. The proposed method showed an increase in sensitivity at least 2 log units for all the NV strains tested compared with the standard RT-PCR method. Higher sensitivity was confirmed in tests on experimentally and naturally contaminated shellfish. (+info)
Chronic liver fluke disease with dyspepsia: a case report.
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BACKGROUND: Chronic liver fluke disease with dyspepsia is rarely seen clinically. In this study, we assessed the etiological factors, symptoms, physical signs and diadynamic methods in a case of chronic liver fluke disease with dyspepsia. METHODS: Physical examination, laboratory studies, ultrasonography and CT scan were performed before pathogen examination. The eggs of fluke found with the inverted sedimentation method were also observed under a microscopy. They were diagnosed as the eggs of Clonorchis sinensis. RESULTS: The patient was diagnosed as having chronic liver fluke disease, and his appetite recovered after three courses of treatment with praziquantel. CONCLUSION: Eating fresh fish and shrimp might cause liver fluke disease. The symptoms of this disease with dyspepsia can be anorexia, abdominal distention, bellyache, and loose stools. (+info)
Detection of pathogenic Vibrio spp. in shellfish by using multiplex PCR and DNA microarrays.
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This study describes the development of a gene-specific DNA microarray coupled with multiplex PCR for the comprehensive detection of pathogenic vibrios that are natural inhabitants of warm coastal waters and shellfish. Multiplex PCR with vvh and viuB for Vibrio vulnificus, with ompU, toxR, tcpI, and hlyA for V. cholerae, and with tlh, tdh, trh, and open reading frame 8 for V. parahaemolyticus helped to ensure that total and pathogenic strains, including subtypes of the three Vibrio spp., could be detected and discriminated. For DNA microarrays, oligonucleotide probes for these targeted genes were deposited onto epoxysilane-derivatized, 12-well, Teflon-masked slides by using a MicroGrid II arrayer. Amplified PCR products were hybridized to arrays at 50 degrees C and detected by using tyramide signal amplification with Alexa Fluor 546 fluorescent dye. Slides were imaged by using an arrayWoRx scanner. The detection sensitivity for pure cultures without enrichment was 10(2) to 10(3) CFU/ml, and the specificity was 100%. However, 5 h of sample enrichment followed by DNA extraction with Instagene matrix and multiplex PCR with microarray hybridization resulted in the detection of 1 CFU in 1 g of oyster tissue homogenate. Thus, enrichment of the bacterial pathogens permitted higher sensitivity in compliance with the Interstate Shellfish Sanitation Conference guideline. Application of the DNA microarray methodology to natural oysters revealed the presence of V. vulnificus (100%) and V. parahaemolyticus (83%). However, V. cholerae was not detected in natural oysters. An assay involving a combination of multiplex PCR and DNA microarray hybridization would help to ensure rapid and accurate detection of pathogenic vibrios in shellfish, thereby improving the microbiological safety of shellfish for consumers. (+info)
Common whelk (Buccinum undatum) allergy: identification of IgE-binding components and effects of heating and digestive enzymes.
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In Korea, common whelk (Buccinum undatum) is a popular edible shellfish. The aim of this study was to observe the sensitization rate to common whelk and to characterize its allergens. We carried out skin prick test (SPT) in 1,700 patients with various allergic diseases. Specific IgE were detected by ELISA in the patient sera and ELISA inhibition tests were conducted. IgE-binding components were identified by means of SDS-PAGE and IgE-immunoblotting. The effects of digestive enzymes were evaluated in both raw and thermally treated extracts. SPT to common whelk was positive (>/=2+) in 83 (4.9%) patients studied. Twenty-four (38.7%) out of 62 SPT positive patients had high serum specific IgE to common whelk. ELISA inhibition test showed significant inhibitions by abalone as well as by common whelk. IgE-immunoblotting demonstrated three IgE-binding components (40, 71, 82 kDa), which were digested by simulated intestinal fluid and moderately digested by simulated gastric fluid, and the digestibility of allergens remained unchanged after thermal treatment. In conclusion, IgE-sensitization rate to common whelk was 4.9% in allergy patients. IgE-immunoblotting demonstrated three IgE-binding components, which were degraded by digestive enzymes. Further studies are needed to evaluate the clinical significance of the sensitized patients to common whelk. (+info)
High-pressure inactivation of hepatitis A virus within oysters.
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Previous results demonstrated that hepatitis A virus (HAV) could be inactivated by high hydrostatic pressure (HHP) (D. H. Kingsley, D. Hoover, E. Papafragkou, and G. P. Richards, J. Food Prot. 65:1605-1609, 2002); however, direct evaluation of HAV inactivation within contaminated oysters was not performed. In this study, we report confirmation that HAV within contaminated shellfish is inactivated by HHP. Shellfish were initially contaminated with HAV by using a flowthrough system. PFU reductions of >1, >2, and >3 log(10) were observed for 1-min treatments at 350, 375, and 400 megapascals, respectively, within a temperature range of 8.7 to 10.3 degrees C. Bioconcentration of nearly 6 log(10) PFU of HAV per oyster was achieved under simulated natural conditions. These results suggest that HHP treatment of raw shellfish will be a viable strategy for the reduction of infectious HAV. (+info)