Using low-coverage whole genome sequencing (genome skimming) to delineate three introgressed species of buffalofish (Ictiobus).

Consumption of buffalofish has been sporadically associated with Haff disease-like illnesses involving sudden onset muscle pain and weakness due to skeletal muscle rhabdomyolysis, but determination of precisely which species are associated with these illnesses has been impeded by a lack of species-specific DNA-based markers. Here, three closely related species of buffalofish native to the Mississippi River Basin (Ictiobus bubalus, Ictiobus cyprinellus and Ictiobus niger) that have previously proven genetically indistinguishable using both mitochondrial and nuclear single-locus sequencing were reliably discriminated using low-coverage whole genome sequencing ('genome skimming'). Using 44 specimens representing the three species collected from the mid/upper (Missouri) and lower (Louisiana) regions of the species' native ranges, the SISRS (Site Identification from Short Read Sequences) bioinformatics pipeline was adapted to (1) identify over 620Mbp of putatively homologous nuclear sequence data and (2) isolate over 140,000 single-nucleotide polymorphisms (SNPs) that supported accurate species delimitation, all without the use of a reference genome or annotation data. These sites were used to classify Ictiobus spp. samples with genome-skim data, along with a larger set (n = 67) where ultraconserved elements (UCEs) were sequenced. Analyses of whole mitochondrial data revealed more limited signal. Nearly all samples matched their purported species based on morphologic identification, but two Missouri samples morphologically identified as I. niger grouped with samples of I. bubalus, albeit with significant enrichment of I. niger SNPs. To our knowledge this is the first report of a DNA-based tool to reliably discriminate these three morphologically distinct species.

A survey of Dinophysis spp. and their potential to cause diarrhetic shellfish poisoning in coastal waters of the United States.

Multiple species of the genus Dinophysis produce diarrhetic shellfish toxins (okadaic acid and Dinophysis toxins, OA/DTXs analogs) and/or pectenotoxins (PTXs). Only since 2008 have DSP events (illnesses and/or shellfish harvesting closures) become recognized as a threat to human health in the United States. This study characterized 20 strains representing five species of Dinophysis spp. isolated from three US coastal regions that have experienced DSP events: the Northeast/Mid-Atlantic, the Gulf of Mexico, and the Pacific Northwest. Using a combination of morphometric and DNA-based evidence, seven Northeast/Mid-Atlantic isolates and four Pacific Northwest isolates were classified as D. acuminata, a total of four isolates from two coasts were classified as D. norvegica, two isolates from the Pacific Northwest coast were identified as D. fortii, and three isolates from the Gulf of Mexico were identified as D. ovum and D. caudata. Toxin profiles of D. acuminata and D. norvegica varied by their geographical origin within the United States. Cross-regional comparison of toxin profiles was not possible with the other three species; however, within each region, distinct species-conserved profiles for isolates of D. fortii, D. ovum, and D. caudata were observed. Historical and recent data from various State and Tribal monitoring programs were compiled and compared, including maximum recorded cell abundances of Dinophysis spp., maximum concentrations of OA/DTXs recorded in commercial shellfish species, and durations of harvesting closures, to provide perspective regarding potential for DSP impacts to regional public health and shellfish industry.

Ciguatoxin in Hawai'i: Fisheries forecasting using geospatial and environmental analyses for the invasive Cephalopholis argus (Epinephelidae).

Invasive species can precede far-reaching environmental and economic consequences. In the Hawai'ian Archipelago Cephalopholis argus (family Serranidae) is an established invasive species, now recognized as the dominant local reef predator, negatively impacting the native ecosystem and local fishery. In this region, no official C. argus fishery exists, due to its association with Ciguatera seafood poisoning (CP); a severe intoxication in humans occurring after eating (primarily) fish contaminated with ciguatoxins (CTXs). Pre-harvest prediction of CP is currently not possible; partly due to the ubiquitous nature of the microalgae producing CTXs and the diverse bioaccumulation pathways of the toxins. This study investigated the perceived risk of CP in two geographically discrete regions (Leeward and Windward) around the main island of Hawai'i, guided by local fishers. C. argus was collected and investigated for CTXs using the U.S. Food and Drug Administration (FDA) CTX testing protocol (in vitro neuroblastoma N2a-assay and LC-MS/MS). Overall, 76% of fish (87/113) exceeded the FDA guidance value for CTX1B (0.01 ng g-1 tissue equivalents); determined by the N2a-assay. Maximum CTX levels were ≅2× higher at the Leeward vs Windward location and, respectively, 95% (64/67) and 54% (25/46) of fish were positive for CTX-like activity. Fisher persons and environmental understandings, regarding the existence of a geographic predictor (Leeward vs Windward) for harvest, were found to be (mostly) accurate as CTXs were detected in both locations and the local designation of C. argus as a risk for CP was confirmed. This study provides additional evidence that supports the previous conclusions that this species is a severe CP risk in the coastal food web of Hawai'i, and that ocean exposure (wave power) may be a prominent factor influencing the CTX content in fish within a hyperendemic region for CP.

Characterization of Dinophysis spp. (Dinophyceae, Dinophysiales) from the mid-Atlantic region of the United States1.

Due to the increasing prevalence of Dinophysis spp. and their toxins on every US coast in recent years, the need to identify and monitor for problematic Dinophysis populations has become apparent. Here, we present morphological analyses, using light and scanning electron microscopy, and rDNA sequence analysis, using a ~2-kb sequence of ribosomal ITS1, 5.8S, ITS2, and LSU DNA, of Dinophysis collected in mid-Atlantic estuarine and coastal waters from Virginia to New Jersey to better characterize local populations. In addition, we analyzed for diarrhetic shellfish poisoning (DSP) toxins in water and shellfish samples collected during blooms using liquid-chromatography tandem mass spectrometry and an in vitro protein phosphatase inhibition assay and compared this data to a toxin profile generated from a mid-Atlantic Dinophysis culture. Three distinct morphospecies were documented in mid-Atlantic surface waters: D. acuminata, D. norvegica, and a "small Dinophysis sp." that was morphologically distinct based on multivariate analysis of morphometric data but was genetically consistent with D. acuminata. While mid-Atlantic D. acuminata could not be distinguished from the other species in the D. acuminata-complex (D. ovum from the Gulf of Mexico and D. sacculus from the western Mediterranean Sea) using the molecular markers chosen, it could be distinguished based on morphometrics. Okadaic acid, dinophysistoxin 1, and pectenotoxin 2 were found in filtered water and shellfish samples during Dinophysis blooms in the mid-Atlantic region, as well as in a locally isolated D. acuminata culture. However, DSP toxins exceeded regulatory guidance concentrations only a few times during the study period and only in noncommercial shellfish samples.

Genomics overrules mitochondrial DNA, siding with morphology on a controversial case of species delimitation.

Species delimitation is a major quest in biology and is essential for adequate management of the organismal diversity. A challenging example comprises the fish species of red snappers in the Western Atlantic. Red snappers have been traditionally recognized as two separate species based on morphology: Lutjanus campechanus (northern red snapper) and L. purpureus (southern red snapper). Recent genetic studies using mitochondrial markers, however, failed to delineate these nominal species, leading to the current lumping of the northern and southern populations into a single species ( L. campechanus). This decision carries broad implications for conservation and management as red snappers have been commercially over-exploited across the Western Atlantic and are currently listed as vulnerable. To address this conflict, we examine genome-wide data collected throughout the range of the two species. Population genomics, phylogenetic and coalescent analyses favour the existence of two independent evolutionary lineages, a result that confirms the morphology-based delimitation scenario in agreement with conventional taxonomy. Despite finding evidence of introgression in geographically neighbouring populations in northern South America, our genomic analyses strongly support isolation and differentiation of these species, suggesting that the northern and southern red snappers should be treated as distinct taxonomic entities.

Evaluation of Rapid, Early Warning Approaches to Track Shellfish Toxins Associated with Dinophysis and Alexandrium Blooms.

Marine biotoxin-contaminated seafood has caused thousands of poisonings worldwide this century. Given these threats, there is an increasing need for improved technologies that can be easily integrated into coastal monitoring programs. This study evaluates approaches for monitoring toxins associated with recurrent toxin-producing Alexandrium and Dinophysis blooms on Long Island, NY, USA, which cause paralytic and diarrhetic shellfish poisoning (PSP and DSP), respectively. Within contrasting locations, the dynamics of pelagic Alexandrium and Dinophysis cell densities, toxins in plankton, and toxins in deployed blue mussels (Mytilus edulis) were compared with passive solid-phase adsorption toxin tracking (SPATT) samplers filled with two types of resin, HP20 and XAD-2. Multiple species of wild shellfish were also collected during Dinophysis blooms and used to compare toxin content using two different extraction techniques (single dispersive and double exhaustive) and two different toxin analysis assays (liquid chromatography/mass spectrometry and the protein phosphatase inhibition assay (PP2A)) for the measurement of DSP toxins. DSP toxins measured in the HP20 resin were significantly correlated (R² = 0.7-0.9, p < 0.001) with total DSP toxins in shellfish, but were detected more than three weeks prior to detection in deployed mussels. Both resins adsorbed measurable levels of PSP toxins, but neither quantitatively tracked Alexandrium cell densities, toxicity in plankton or toxins in shellfish. DSP extraction and toxin analysis methods did not differ significantly (p > 0.05), were highly correlated (R² = 0.98-0.99; p < 0.001) and provided complete recovery of DSP toxins from standard reference materials. Blue mussels (Mytilus edulis) and ribbed mussels (Geukensia demissa) were found to accumulate DSP toxins above federal and international standards (160 ng g-1) during Dinophysis blooms while Eastern oysters (Crassostrea virginica) and soft shell clams (Mya arenaria) did not. This study demonstrated that SPATT samplers using HP20 resin coupled with PP2A technology could be used to provide early warning of DSP, but not PSP, events for shellfish management.

Tetrodotoxin poisoning outbreak from imported dried puffer fish--Minneapolis, Minnesota, 2014.

On June 13, 2014, two patients went to the Hennepin County Medical Center Emergency Department in Minneapolis, Minnesota, with symptoms suggestive of tetrodotoxin poisoning (i.e., oral paresthesias, weakness, and dyspnea) after consuming dried puffer fish (also known as globefish) purchased during a recent visit to New York City. The patients said two friends who consumed the same fish had similar, although less pronounced, symptoms and had not sought care. The Minnesota Department of Health conducted an investigation to determine the source of the product and samples were sent to the Food and Drug Administration (FDA) Center for Food Safety and Applied Nutrition for chemical and genetic analysis. Genetic analysis identified the product as puffer fish (Lagocephalus lunaris) and chemical analysis determined it was contaminated with high levels of tetrodotoxin. A traceback investigation was unable to determine the original source of the product. Tetrodotoxin is a deadly, potent poison; the minimum lethal dose in an adult human is estimated to be 2-3 mg. Tetrodotoxin is a heat-stable and acid-stable, nonprotein, alkaloid toxin found in many species of the fish family Tetraodontidae (puffer fish) as well as in certain gobies, amphibians, invertebrates, and the blue-ringed octopus. Tetrodotoxin exerts its effects by blocking voltage-activated sodium channels, terminating nerve conduction and muscle action potentials, leading to progressive paralysis and, in extreme cases, to death from respiratory failure. Because these fish were reportedly purchased in the United States, they pose a substantial U.S. public health hazard given the potency of the toxin and the high levels of toxin found in the fish.

Suspected Palytoxin Inhalation Exposures Associated with Zoanthid Corals in Aquarium Shops and Homes - Alaska, 2012-2014.

On August 12, 2014, an Anchorage hospital notified the Alaska Section of Epidemiology (SOE) that a middle-aged male resident of Anchorage (patient A) had arrived in the emergency department with possible palytoxin exposure. Patient A complained of a bitter metallic taste, fever, weakness, cough, and muscle pain 7-8 hours after introduction of live zoanthid coral into his home aquarium. Palytoxin, a potent toxin known to produce the reported effects, is contained in zoanthid marine corals.

Ichthyotoxic Karlodinium veneficum (Ballantine) J Larsen in the Upper Swan River Estuary (Western Australia): Ecological conditions leading to a fish kill.

Ichthyotoxic Karlodinium veneficum has become a persistent problem in the eutrophic Swan River Estuary (SRE) near Perth, Western Australia. Karlotoxin (KmTx) concentrations and K. veneficum were sampled from March to July 2005, spanning a bloom confirmed by microscopy and genetics (ITS sequence), and a fish kill coincident with end of the bloom. The objective of this study was to investigate K. veneficum cell and toxin dynamics, and water quality conditions, leading up to the bloom and fish kill in this estuarine system. Abundance of K. veneficum increased as diatom abundance decreased over a 3-month period (Jan-Mar) preceding the bloom. Low freshwater flow to the SRE characterized the bloom initiation period, while elevated seasonal flows altered water quality and preceded the end of the bloom and fish kill. The bloom of K. veneficum was localized over a bottom layer of hypoxic water in a stratified water column. Low nitrate levels, DIN:DIP (mol) near unity, and particulate C:N:P of K. veneficum-rich water samples were consistent with nitrogen limitation of phytoplankton. A KmTx 2 congener was present in the concentration range 0-1052 ng KmTx mL-1, levels that were sufficient to kill larval fish in the laboratory within 4 h. A KmTx cell quota of 2.8 pg KmTx cell-1 was estimated for the bloom, which is moderately high for the species. Gill histopathology of fish from this fish kill showed signs of damage similar to those caused by KmTx in the lab. Results from this study suggest that conditions in the SRE, including elevated K. veneficum abundance and KmTx cell quotas, as well as hypoxia in the upper SRE, likely contribute to seasonal fish kills observed in this system.

PSP toxin levels and plankton community composition and abundance in size-fractionated vertical profiles during spring/summer blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine and on Georges Bank, 2007, 2008, and 2010: 2. Plankton community composition and abundance.

As part of the Gulf of Maine Toxicity (GOMTOX) project, we determined Alexandrium fundyense abundance, paralytic shellfish poisoning (PSP) toxin levels in various plankton size fractions, and the community composition of potential grazers of A. fundyense in plankton size fractions during blooms of this toxic dinoflagellate in the coastal Gulf of Maine and on Georges Bank in spring and summer of 2007, 2008, and 2010. PSP toxins and A. fundyense cells were found throughout the sampled water column (down to 50 m) in the 20-64 µm size fractions. While PSP toxins were widespread throughout all size classes of the zooplankton grazing community, the majority of the toxin was measured in the 20-64 µm size fraction. A. fundyense cellular toxin content estimated from field samples was significantly higher in the coastal Gulf of Maine than on Georges Bank. Most samples containing PSP toxins in the present study had diverse assemblages of grazers. However, some samples clearly suggested PSP toxin accumulation in several different grazer taxa including tintinnids, heterotrophic dinoflagellates of the genus Protoperidinium, barnacle nauplii, the harpacticoid copepod Microsetella norvegica, the calanoid copepods Calanus finmarchicus and Pseudocalanus spp., the marine cladoceran Evadne nordmanni, and hydroids of the genus Clytia. Thus, a diverse assemblage of zooplankton grazers accumulated PSP toxins through food-web interactions. This raises the question of whether PSP toxins pose a potential human health risk not only from nearshore bivalve shellfish, but also potentially from fish and other upper-level consumers in zooplankton-based pelagic food webs.

PSP toxin levels and plankton community composition and abundance in size-fractionated vertical profiles during spring/summer blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine and on Georges Bank, 2007, 2008, and 2010: 1. Toxin levels.

As part of the NOAA ECOHAB funded Gulf of Maine Toxicity (GOMTOX) project, we determined Alexandrium fundyense abundance, paralytic shellfish poisoning (PSP) toxin composition, and concentration in quantitatively-sampled size-fractionated (20-64, 64-100, 100-200, 200-500, and > 500 µm) particulate water samples, and the community composition of potential grazers of A. fundyense in these size fractions, at multiple depths (typically 1, 10, 20 m, and near-bottom) during 10 large-scale sampling cruises during the A. fundyense bloom season (May-August) in the coastal Gulf of Maine and on Georges Bank in 2007, 2008, and 2010. Our findings were as follows: (1) when all sampling stations and all depths were summed by year, the majority (94% ± 4%) of total PSP toxicity was contained in the 20-64 µm size fraction; (2) when further analyzed by depth, the 20-64 µm size fraction was the primary source of toxin for 97% of the stations and depths samples over three years; (3) overall PSP toxin profiles were fairly consistent during the three seasons of sampling with gonyautoxins (1, 2, 3, and 4) dominating (90.7% ± 5.5%), followed by the carbamate toxins saxitoxin (STX) and neosaxitoxin (NEO) (7.7% ± 4.5%), followed by n-sulfocarbamoyl toxins (C1 and 2, GTX5) (1.3% ± 0.6%), followed by all decarbamoyl toxins (dcSTX, dcNEO, dcGTX2&3) (< 1%), although differences were noted between PSP toxin compositions for nearshore coastal Gulf of Maine sampling stations compared to offshore Georges Bank sampling stations for 2 out of 3 years; (4) surface cell counts of A. fundyense were a fairly reliable predictor of the presence of toxins throughout the water column; and (5) nearshore surface cell counts of A. fundyense in the coastal Gulf of Maine were not a reliable predictor of A. fundyense populations offshore on Georges Bank for 2 out of the 3 years sampled.

Protocol for building a reference standard sequence library for DNA-based seafood identification.

With the recent adoption of a DNA sequencing-based method for the species identification for seafood products by the U.S. Food and Drug Administration (FDA), a library of standard sequences derived from reference specimens with authoritative taxonomic authentication was required. Provided here are details of how the FDA and its collaborators are building this reference standard sequence library that will be used to confirm the accurate labeling of seafood products sold in interstate commerce in the United States. As an example data set from this library, information for 117 fish reference standards, representing 94 species from 43 families in 15 orders, collected over a 4-year period from the Gulf of Mexico, U.S., that are now stored at the Smithsonian Museum Support Center in Suitland, MD, are provided.

Structure and toxicity of AZA-59, an azaspiracid shellfish poisoning toxin produced by Azadinium poporum (Dinophyceae).

To date, the putative shellfish toxin azaspiracid 59 (AZA-59) produced by Azadinium poporum (Dinophyceae) has been the only AZA found in isolates from the Pacific Northwest coast of the USA (Northeast Pacific Ocean). Anecdotal reports of sporadic diarrhetic shellfish poisoning-like illness, with the absence of DSP toxin or Vibrio contamination, led to efforts to look for other potential toxins, such as AZAs, in water and shellfish from the region. A. poporum was found in Puget Sound and the outer coast of Washington State, USA, and a novel AZA (putative AZA-59) was detected in low quantities in SPATT resins and shellfish. Here, an A. poporum strain from Puget Sound was mass-cultured and AZA-59 was subsequently purified and structurally characterized. In vitro cytotoxicity of AZA-59 towards Jurkat T lymphocytes and acute intraperitoneal toxicity in mice in comparison to AZA-1 allowed the derivation of a provisional toxicity equivalency factor of 0.8 for AZA-59. Quantification of AZA-59 using ELISA and LC-MS/MS yielded reasonable quantitative results when AZA-1 was used as an external reference standard. This study assesses the toxic potency of AZA-59 and will inform guidelines for its potential monitoring in case of increasing toxin levels in edible shellfish.

Biodiversity of Philippine marine fishes: A DNA barcode reference library based on voucher specimens.

Accurate identification of fishes is essential for understanding their biology and to ensure food safety for consumers. DNA barcoding is an important tool because it can verify identifications of both whole and processed fishes that have had key morphological characters removed (e.g., filets, fish meal); however, DNA reference libraries are incomplete, and public repositories for sequence data contain incorrectly identified sequences. During a nine-year sampling program in the Philippines, a global biodiversity hotspot for marine fishes, we developed a verified reference library of cytochrome c oxidase subunit I (COI) sequences for 2,525 specimens representing 984 species. Specimens were primarily purchased from markets, with additional diversity collected using rotenone or fishing gear. Species identifications were verified based on taxonomic, phenotypic, and genotypic data, and sequences are associated with voucher specimens, live-color photographs, and genetic samples catalogued at Smithsonian Institution, National Museum of Natural History. The Biodiversity of Philippine Marine Fishes dataset is released herein to increase knowledge of species diversity and distributions and to facilitate accurate identification of market fishes.

Haff disease associated with consumption of buffalofish (Ictiobus spp.) in the United States, 2010-2020, with confirmation of the causative species.

BACKGROUND: In the United States, buffalofish (Ictiobus spp.) are sporadically associated with sudden onset muscle pain and weakness due to rhabdomyolysis within 24 h of fish consumption (Haff disease). Previous genetic analyses of case-associated samples were unable to distinguish the three species of buffalofish that occur in the US, Ictiobus cyprinellus (bigmouth buffalo), Ictiobus bubalus (smallmouth buffalo), and Ictiobus niger (black buffalo). METHODS: Ten events were investigated between 2010 and 2020 and demographic and clinical information was collected for 24 individuals. Meal remnants were collected from 5 of 10 events with additional associated samples (n = 24) collected from another five of 10 events. Low-coverage whole-genome sequencing (genome skimming) was used to identify meal remnants. RESULTS: Patients (26-75 years of age) ranged from 1-4 per event, with 90% involving ≥2 individuals. Reported symptoms included muscle tenderness and weakness, nausea/vomiting, and brown/tea-colored urine. Median incubation period was 8 h. Ninety-six percent of cases were hospitalized with a median duration of four days. The most commonly reported laboratory finding was elevated creatine phosphokinase and liver transaminases. Treatment was supportive including intravenous fluids to prevent renal failure. Events occurred in California (1), Illinois (2), Louisiana (1), New York (1), Mississippi (1), Missouri (2), New Jersey (1), and Texas (1) with location of harvest, when known, being Illinois, Louisiana, Mississippi, Missouri, Texas, and Wisconsin. Meal remnants were identified as I. bubalus (n = 4) and I. niger (n = 1). Associated samples were identified as I. bubalus (n = 16), I. cyprinellus (n = 5), and I. niger (n = 3). DISCUSSION: Time course, presentation of illness, and clinical findings were all consistent with previous domestic cases of buffalofish-associated Haff disease. In contrast to previous reports that I. cyprinellus is the causative species in US cases, data indicate that all three buffalofish species are harvested but I. bubalus is most often associated with illness.

Antibody characterization and immunoassays for palytoxin using an SPR biosensor.

Palytoxin (PLTX), a polyether marine toxin originally isolated from the zoanthid Palythoa toxica, is one of the most toxic non-protein substances known. Fatal poisonings have been linked to ingestion of PLTX-contaminated seafood, and effects in humans have been associated with dermal and inhalational exposure to PLTX containing organisms and waters. Additionally, PLTX co-occurrence with other well-characterized seafood toxins (e.g., ciguatoxins, saxitoxins, tetrodotoxin) has hindered direct associations of PLTX to seafood-borne illnesses. There are currently no validated methods for the quantitative detection of PLTX(s). As such, a well-characterized, robust, specific analytical technique is needed for the detection of PLTX(s) in source organisms, surrounding waters, and clinical samples. Surface plasmon resonance (SPR) biosensors are ideally suited for antibody characterization and quantitative immunoassay detection. Herein, we describe a newly developed SPR assay for PLTX. An anti-mouse substrate was used to characterize the kinetic values for a previously developed monoclonal anti-PLTX. The characterized antibody was then incorporated into a sensitive, rapid, and selective PLTX assay. Buffer type, flow rate, analyte-binding time, and regeneration conditions were optimized for the antibody-PLTX system. Cross-reactivity to potentially co-occurring seafood toxins was also evaluated. We show that this optimized assay is capable of measuring low- to sub-ng/mL PLTX levels in buffer and two seafood matrices (grouper and clam). Preliminary results indicate that this SPR biosensor assay allows for (1) rapid characterization of antibodies and (2) rapid, sensitive PLTX concentration determination in seafood matrices. Method development information contained herein may be broadly applied to future PLTX detection and/or antibody characterization efforts.

Surface plasmon resonance biosensor for determination of tetrodotoxin: prevalidation study.

A label-free surface plasmon resonance biosensor method was applied to determine tetrodotoxin (TTX) in pufferfish matrixes using an antibody inhibition assay format. A prevalidation study was conducted to demonstrate the assay performance characteristics, such as selectivity, LOD, LOQ, repeatability, reproducibility, and accuracy. Three participating laboratories reported standard curves in buffer and pufferfish matrix. A set of blind samples with TTX spiked into buffer as well as in 10% pufferfish extract were analyzed. Additionally, three blind naturally contaminated samples were analyzed, and the results were compared to those obtained using a reference method (HPLC/electrospray ionization-selected reaction monitoring-MS). The developed method was demonstrated to be capable of detecting TTX in pufferfish matrix standard samples in a broad concentration range (2-9000 ng/mL) with an LOD of 1.5 ng/mL. Between-laboratory recovery values were in the range of 51-190% with a mean of 107%, and 64-180% with a mean of 103% for TTX-spiked samples in buffer and pufferfish matrix, respectively. Between-laboratory recoveries were in the satisfactory range of 101-119% for naturally contaminated samples. This robust, rapid, and noninvasive method may serve as an attractive alternative to established methods for detection of TTX in pufferfish extracts.

A single-laboratory validated method for the generation of DNA barcodes for the identification of fish for regulatory compliance.

The U.S. Food and Drug Administration is responsible for ensuring that the nation's food supply is safe and accurately labeled. This task is particularly challenging in the case of seafood where a large variety of species are marketed, most of this commodity is imported, and processed product is difficult to identify using traditional morphological methods. Reliable species identification is critical for both foodborne illness investigations and for prevention of deceptive practices, such as those where species are intentionally mislabeled to circumvent import restrictions or for resale as species of higher value. New methods that allow accurate and rapid species identifications are needed, but any new methods to be used for regulatory compliance must be both standardized and adequately validated. "DNA barcoding" is a process by which species discriminations are achieved through the use of short, standardized gene fragments. For animals, a fragment (655 base pairs starting near the 5' end) of the cytochrome c oxidase subunit 1 mitochondrial gene has been shown to provide reliable species level discrimination in most cases. We provide here a protocol with single-laboratory validation for the generation of DNA barcodes suitable for the identification of seafood products, specifically fish, in a manner that is suitable for FDA regulatory use.

Structure and relative potency of several karlotoxins from Karlodinium veneficum.

The karlotoxins are a family of amphidinol-like compounds that play roles in avoiding predation and in prey capture for the toxic dinoflagellate Karlodinium veneficum. The first member of the toxin group to be reported was KmTx 1 (1), and here we report an additional five new members of this family (3-7) from the same strain. Of these additional compounds, KmTx 3 (3) differs from KmTx 1 (1) in having one less methylene group in the saturated portion of its lipophilic arm. In addition, 64-E-chloro-KmTx 3 (4) and 10-O-sulfo-KmTx 3 (5) were identified. Likewise, 65-E-chloro-KmTx 1 (6) and 10-O-sulfo-KmTx 1 (7) were also isolated. Comparison of the hemolytic activities of the newly isolated compounds to that of KmTx 1 shows that potency correlates positively with the length of the lipophilic arm and is disrupted by sulfonation of the polyol arm.

Real-time PCR assay for the detection of pufferfish products.

An assay was developed for the rapid detection of products containing tissues from potentially toxic pufferfish (family Tetraodontidae), as part of the U.S. Food and Drug Administration Center for Veterinary Medicine and Center for Food Safety and Applied Nutrition's charter to protect human health. In this study, we developed a TaqMan assay derived from DNA barcode data (650 bp starting at the 5' end of the mitochondrial cytochrome c oxidase I gene) for the specific detection of pufferfish. The method requires only 1 h of total run time, a significant improvement over current methods, which can require 24 to 96 h for completion. The probes were tested against 105 species of fish and were able to detect 20 species of pufferfish; no cross-reactivity was shown with 85 species of nonpufferfish, including 20 related species from the same order (Tetraodontiformes). These results demonstrate that this assay is suitable for the rapid and specific detection of pufferfish and that it could be a useful regulatory tool to protect human health.