Total Toxin Research Articles

Paralytic Shellfish Poison (PSP) Profiles and Toxification of Short-necked Clams Fed with the Toxic Dinoflagellate Alexandrium tamarense

As a part of our studies on paralytic shellfish poison (PSP) accumulation kinetics in bivalves, short-necked clam Tapes japonia was experimentally contaminated with PSP by being fed with the toxic dinoflagellate Alexandrium tamarense for 2, 4, 6, 8 and 10 days, and the processes of PSP accumulation and bioconversion were investigated: the toxicity level was determined by mouse bioassay and toxin components were identified by high-performance liquid chromatography (HPLC). The strain of A. tamarense used in this study possessed a specific toxicity of 186.7 +/- 81 (mean +/- S.D., n = 5) x 10(-6) MU/cell. Total toxin concentration of this strain was 140.4 +/- 61 (mean S.D., n = 5) fmol/cell. The toxicity level of short-necked clams increased almost in parallel with the abundance of A. tamarense, reaching 1.8, 3.2, 3.8, 3.5 and 4.6 MU/g meat for 2, 4, 6, 8 and 10 days of feeding, respectively. The accumulation rates of PSP toxins, which are the ratio of the total amount of toxins accumulated in the bivalves to the estimated intake in each feeding experiment, were 7.5, 8.1, 5.7, 4.2 and 4.4% for 2, 4, 6, 8 and 10 days, respectively. At the end of each exposure period, many undigested algal cells were found in pseudofeces under microscopic observation. There was a remarkable difference in the relative proportions of the predominant toxin components between A. tamarense and short-necked clams. The most notable difference was the change in the relative amounts of C2 (carbamoyl-N-sulfo-11beta-hydroxysaxitoxin sulfate), GTX1 and GTX 4 during the first two days. In the toxic bivalves, the amount of C2, which is dominant in A. tamarense, decreased to below half a percent after being ingested. Subsequently, the amount of GTX1 in the shellfish meat reached 50.1 mol%, while that of GTX4 decreased to about half of that in A. tamarense. As for the configuration of 11-hydroxysulfate, PSP components in A. tamarense exist almost exclusively as beta-epimers (GTX3, GTX4, C2 and C4), accounting for 72.8 mol% of the total. This contrasts with the case of the short-necked clams, where the beta-epimers represented 25.8, 33.8, 30.8, 36.8 and 28.5 mol% of the total after 2, 4, 6, 8 and 10 days, respectively. PSP components seemed to be converted rapidly at an early stage of the feeding of A. tamarense.

Occurrence of Paralytic Shellfish Poison (PSP)-Producing Dinoflagellate Alexandrium tamarense in Hiroshima Bay, Hiroshima Prefecture, Japan, during 1993-2004 and Its PSP Profiles

To assess levels of shellfish intoxication by the paralytic shellfish poison (PSP)-producing dinoflagellate Alexandrium tamarense, potential health risks to human shellfish consumers and the possible need for regulatory intervention, yearly variations of maximum cell density of this species were examined from 1993 to 2004 in Kure Bay and Kaita Bay, which are located within Hiroshima Bay, Hiroshima Prefecture, Japan. The seawater temperature was determined concomitantly. In Kure Bay, maximum concentrations of 1,400 and 1,300 cells/mL at 0 and 5 m depths were observed on 21 and 24 April 1997. In Kaita Bay, remarkably high concentrations above 1,000 cells/mL of A. tamarense were observed in two out of three years investigated. These facts suggest that the environment in both bays is favorable for the propagation of A. tamarense. The temperature range at which the natural population of A. tamarense blooms was generally from 12 to 16 degrees C. Four strains (ATKR-94, -95, -97 and -01) from Kure Bay and one strain (ATKT-97) from Kaita Bay were established. The strain ATKR-94, cultured in modified SW-2 medium at 15 degrees C for 15 days, showed a specific toxicity of 33.8 x 10(-6) MU/cell. The toxins in all five strains exist almost exclusively as beta-epimers (C2 (PX2 or GTX8), GTX3, dcGTX3 and GTX4), which accounted for 54.9 to 73.0 mol% of the total. The corresponding a-epimers (C1 (PX1 or epi-GTX8), GTX2, dcGTX2 and GTX1) accounted for 6.0 to 28.9 mol%. The toxin profiles of ATKR-97 and ATKT-97 were characterized by unusually high proportions of low-potency sulfocarbamoyl toxin, which comprised 62.4 and 68.2 mol%, respectively, of total toxins. In the toxic bivalves, the low-toxicity sulfocarbamoyl components, major components of A. tamarense, were present in amounts of only a few percent, suggesting that in vivo conversion of PSP occurs after ingestion. A comparison of the toxin profiles of the causative dinoflagellate and contaminated bivalves showed that PSP components exist in the bivalves in the form of alpha-epimers, presumably owing to accumulation or storage of the toxins.

Azaspiracid poisoning, the food-borne illness associated with shellfish consumption

Azaspiracid poisoning (AZP) is a recently discovered toxic syndrome that was identified following severe gastrointestinal illness from the consumption of contaminated mussels (Mytilus edulis). The implicated toxins, azaspiracids, are polyethers with unprecedented structural features. Studies toward total toxin synthesis revealed that the initial published structures were incorrect and they have now been revised. These toxins accumulate in bivalve molluscs that feed on toxic microalgae of the genus Protoperidinium, previously considered to be toxicologically benign. Although first identified in shellfish from Ireland, azaspiracid contamination of several types of bivalve shellfish species has now been confirmed throughout the western coastline of Europe. Toxicological studies have indicated that azaspiracids can induce widespread organ damage in mice and that they are probably more dangerous than previously known classes of shellfish toxins. The exclusive reliance on live animal bioassays to monitor azaspiracids in shellfish failed to prevent human intoxications. This was a consequence of poor sensitivity of the assay and the fact that azaspiracids are not exclusively found in the shellfish digestive glands used for toxin testing. The strict regulatory control of azaspiracids in shellfish now requires frequent testing of shellfish using highly specific and sensitive methods involving liquid chromatography-mass spectrometry.

Production of extracellular enzymes and aflatoxins in solid substrate fermentation with aflatoxigenicAspergillus spp.

AflatoxigenicAspergillus flavus andAspergillus parasiticus were subjected to solid substrate fermentation process for 6 days to determine the formation of aflatoxins and production of extracellular enzymes (amyloglucosidase, cellulase, invertase and proteinase). Both organisms produced enzymes which generally increased with fermentation.Aspergillus flavus produced four enzymes whereasA. parasiticus produced three with no proteinase activity.Aspergillus parasiticus produced aflatoxins B1, B2 and G1 but no G2 andA. flavus produced aflatoxins B1 and B2. Invertase showed the highest activity withA. parasiticus and that corresponded with the highest total toxin produced. The enzyme activities were higher withA. parasiticus thanA. flavus although total toxins produced byA. parasiticus were lower than total toxins produced byA. flavus under the same environmental conditions.

Pectenotoxin and okadaic acid-based toxin profiles in Dinophysis acuta and Dinophysis acuminata from New Zealand

The major pectenotoxin and okadaic acid group toxins in Dinophysis acuta and Dinophysis acuminata cell concentrates, collected from various locations around the coast of the South Island of New Zealand (NZ) , were determined by liquid chromatography–tandem mass spectrometry (LC–MS/MS). PTX2 and PTX11 were the major polyether toxins in all Dinophysis spp. cell concentrates. D. acuta contained PTX11 and PTX2 at concentrations of 4.7–64.6 and 32.5–107.5 pg per cell, respectively. The amounts of PTX11 and PTX2 in D. acuminata were much lower at 0.4–2.1 and 2.4–25.8 pg per cell, respectively. PTX seco acids comprised only 4% of the total PTX content of both D. acuta and D. acuminata. D. acuta contained low levels of OA (0.8–2.7 pg per cell) but specimens from the South Island west coast also contained up to 10 times higher levels of OA esters (7.0–10.2 pg per cell). Esterified forms of OA were not observed in D. acuta specimens from the Marlborough Sounds. D. acuta did not contain any DTX1 though all D. acuminata specimens contained DTX1 at levels of 0.1–2.4 pg per cell. DTX2 was not present in any New Zealand Dinophysis spp. specimens. Although the total toxin content varied spatially and temporally, the relative proportions of the various toxins in different specimens from the same location appeared to be relatively stable. The total PTX/total OA ratios in different isolates of D. acuta were very similar (mean±S.E.: 14.9±1.9), although the Marlborough Sounds D. acuminata isolates had a higher total PTX/total OA ratio (mean±S.E.: 22.7±2.4) than the Akaroa Harbour isolates (8.0). No evidence of azaspiracids were detected in these specimens. These results show that the LC–MS/MS monitoring of plankton for PTX group toxins (e.g. PTX2) and their derivatives (e.g. PTX2 seco acid) may provide a sensitive, semi-quantitative, indicator of the presence of more cryptic OA group toxins (e.g. OA esters).

The degradation of Karenia brevis toxins utilizing ozonated seawater

Florida red tides impose both an economic and health impact on the state. The purpose of this research was to examine the effectiveness of ozone to reduce the numbers of Florida red tide organism ( Karenia brevis Davis) and its associated toxins in an artificial seawater environment. The results obtained in this experiment showed an approximate 1.25 log 10 unit reduction in the major toxin groups recovered after 10 min of ozone exposure (approximately 135 mg). In initial trials, K. brevis toxins were extracted and reintroduced into an artificial seawater (ASW) media. Subsequent experiments exposed whole cell K. brevis culture to ozone treatment. Samples from both experiments displayed approximately 1.10 log 10 unit reduction in total toxin and an approximate 1.25 log 10 unit reduction in three of the six major toxins associated with K. brevis (PxTx-1, -2, -9). The reduction in toxin concentration, as measured by high performance liquid chromatography (HPLC) analysis, displayed a positive correlation with the reduction of toxicity as determined by a fish ( Cyprinodon variegatus) bioassay. Despite large total doses of ozone applied, as compared to levels that might be found at a commercial ozonation facility, some toxins were still recoverable by HPLC after ozone treatment.

Screening for cyanobacterial hepatotoxins, microcystins and nodularin in environmental water samples by reversed-phase liquid chromatography–electrospray ionisation mass spectrometry

Water samples taken from 93 freshwater and brackish water locations in Åland (SW Finland) in 2001 were analysed for biomass-bound microcystins and nodularin, cyanobacterial peptide hepatotoxins, by liquid chromatography–mass spectrometry (LC–MS) in selected ion recording (SIR) and multiple reaction monitoring modes, HPLC–UV, and enzyme-linked immunosorbent assay (ELISA). The extracted toxins were separated on a short C 18 column with a gradient of acetonitrile and 0.5% formic acid, and quantified on a Micromass Quattro Micro triple-quadrupole mass spectrometer with an electrospray ion source operated in the positive SIR or scan mode. An injection of 50 pg of microcystin-LR, m/z 995.5, on column gave a signal-to-noise ratio of 17 (peak-to-peak) at the chosen SIR conditions. In-source or MS–MS fragmentation to m/z 135.1, a fragment common to most microcystins and nodularin, was used for confirmatory purposes. Microcystins with a total toxin concentration equal to or higher than 0.2 μg l −1 were confirmed by all three methods in water samples from 14 locations. The highest toxin concentration in a water sample was 42 μg l −1. The most common toxins found were microcystins RR, LR and YR with different degrees of demethylation (non-, mono- or didemethylated). Parallel results achieved with ELISA and HPLC–UV were generally in good agreement with the LC–MS SIR results.

Phycotoxin accumulation in zooplankton feeding on Alexandrium fundyense--vector or sink?

Zooplankton can consume toxic Alexandrium spp. dinoflagellates in the Gulf of Maine and retain paralytic shellfish poisoning (PSP) toxins, potentially acting as toxin vectors. We performed experiments to determine toxin budgets for common species of copepods (Acartia hudsonica, Eurytemora herdmani, Centropages hamatus) feeding on toxic Alexandrium fundyense, offered as monocultures or in mixtures of algal prey, by comparing calculated toxin ingestion rates and toxin content of copepod body tissue and fecal pellets. When fed monocultures, both copepod tissue and fecal pellet fractions accounted for s 5% each of the calculated ingested toxin, and thus by difference ≥ 90% was lost as a dissolved fraction into the seawater medium. The presence of alternative food did not significantly alter the efficiency of toxin retention. Sloppy feeding or regurgitation are probable mechanisms for release of toxin to sea water. Experiments using varying concentrations of A. fundyense and alternative non-toxic species did not show significant acts of cell concentration on toxin retention efficiency. Total toxin retained and efficiency of retention varied among copepod species. Toxin profiles (% molar composition) of dinoflagellates, copepod tissues and fecal pellets differed slightly, suggesting some metabolic transformation. Because of their low retention efficiency, copepod grazers can effectively disperse PSP toxins produced by Alexandrium spp. into the environment, where they are much less likely to be harmful-zooplankton act as a sink for PSP toxins. Nevertheless, sufficient toxin body burdens are attained to contribute to propagation of PSP toxins to other trophic levels.

Food safety implications of the distribution of azaspiracids in the tissue compartments of scallops (Pecten maximus)

Azaspiracids, a new class of shellfish toxins, have been implicated in several recent incidents of human intoxications following the consumption of mussels (Mytilus edulis). A study was undertaken to examine the distribution of azaspiracid poisoning (AZP) toxins in scallops (Pecten maximus) and individual shellfish were dissected into five tissue fractions for the determination of toxin composition. Separation of the predominant azaspiracids, AZA1-3, was achieved using reversed-phase liquid chromatography with detection by positive electrospray multiple tandem mass spectrometry. The AZP toxin composition was determined in the adductor muscle (meat), gonad (roe), hepatopancreas (digestive glands), mantle and gill of scallops. Substantial differences in the AZP toxin levels between tissue compartments were observed and toxins were concentrated predominantly, about 85%, in the hepatopancreas. There was also a significant variation in the total toxin levels between individual scallops from the same sample batch and the RSD was 60% (n = 9). Interestingly, although all three AZP toxins were present in phytoplankton and mussels, AZA3 was not detected in the scallop samples examined. It was concluded that to improve food safety, only the adductor muscle and gonad of scallops should be permitted for sale to the public.

Natural Occurrence and Distribution of Fusarium Toxins in Contaminated Barley Cultivars

Grain samples of 15 naturally contaminated barley cultivars, collected after harvest in southeastern Poland, were analysed for occurrence of Fusarium trichothecenes and zearalenone (ZEA). Barley kernels were contaminated with the following toxic metabolites: deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), nivalenol (NIV), HT-2 toxin (HT-2), T-2 toxin (T-2), diacetoxyscirpenol (DAS), T-2 tetraol and ZEA. Significant correlations between concentrations of individual toxins and the dominant Fusarium species were found. Moreover, significant differences in toxin concentrations between cultivars were detected. Distribution of these mycotoxins was studied in two fractions of kernels (diameter > 2.5 mm and < 2.5 mm). A two-factor analysis of variance revealed significant differences between the two fractions, and between the analysed cultivars. Most of the interactions between fractions and cultivars were also significant. The highest concentration of the analysed toxins was in the fraction of small kernels. Kernel fraction <2.5 mm, although accounting for only 12.8% of sample weight, contained high proportions of the total toxin content: 80% of DON, 94% of NIV, 85% of ZEA, 83% of T-2 tetraol, 80% of DAS, 68% of HT-2 toxin and 81% of T-2 toxin. The results indicate that the level of contamination with Fusarium trichothecenes and ZEA, can be reduced by rejection of small kernels.

Effect of irradiance, temperature and salinity on growth and toxin production by Nodularia spumigena

The object of this work was to determine, using a full-factorial experiment, the influence of temperature, irradiance and salinity on growth and hepatotoxin production by Nodularia spumigena, isolated from Lake Alexandrina in the south-east of South Australia. Higher levels of biomass (determined as particulate organic carbon, POC), toxin production and intracellular toxin concentration per mg POC were produced under light limited conditions (30 μmol m−2 s−1) and at salinities equal to or greater than those experienced in Lake Alexandrina. Both highest biomass and total toxin production rates were recorded at temperatures equal to or greater than those of the lake (20 and 30 °C). The temperature at which maximum biomass and toxin production was recorded decreased from 30 °C for cultures grown at 30 μmol m−2 s−1 to 20 °C when grown at 80 μmol m−2 s−1. In contrast, intracellular toxin per mg POC was highest at the lowest growth temperature, 10 °C, at both 30 and 80 μmol m−2 s−1. It appears that the optimum temperature for biosynthetic pathways used in the production of toxin is lower than the optimum temperature for those pathways associated with growth. Intracellular toxin levels were higher in cells cultured at 10 °C/30 μmol m−2 s−1 whereas the majority of the toxin was extracellular in cells grown at 30 °C/30 μmol m−2 s−1. This implies that the highest concentration of toxin in lake water would occur under high temperature and high irradiance conditions. Individual environmental parameters of salinity, irradiance and temperature were all shown to influence growth and toxin production. Notwithstanding, the overall influence of these three parameters on toxin production was mediated through their effect upon growth rate.

Ubiquitous ‘benign’ alga emerges as the cause of shellfish contamination responsible for the human toxic syndrome, azaspiracid poisoning

A new human toxic syndrome, azaspiracid poisoning (AZP), was identified following illness from the consumption of contaminated mussels ( Mytilus edulis). To discover the aetiology of AZP, sensitive analytical protocols involving liquid chromatography–mass spectrometry (LC–MS) were used to screen marine phytoplankton for azaspiracids. Collections of single species were prepared by manually separating phytoplankton for LC–MS analysis. A dinoflagellate species of the genus, Protoperidinium, has been identified as the progenitor of azaspiracids. Azaspiracid-1, and its analogues, AZA2 and AZA3, were identified in extracts of 200 cells using electrospray multiple tandem MS. This discovery has significant implications for both human health and the aquaculture industry since this phytoplankton genus was previously considered to be toxicologically benign. The average toxin content was 1.8 fmol of total AZA toxins per cell with AZA1 as the predominant toxin, accounting for 82% of the total.

Screening for cyanobacterial hepatotoxins in herring and salmon from the Baltic Sea

Nodularin, a cyclic pentapeptide hepatotoxin closely related to microcystins, is produced by the toxic brackish water cyanobacterium Nodularia spumigena which regularly forms blooms in the Baltic Sea. Baltic herring (Clupea harengus membras L.) and salmon (Salmo salar L.) were caught in the Baltic Sea during 1997 to assess levels of nodularin and microcystins resulting from the blooms. The total toxin content in herring muscle and salmon liver was measured with an enzyme-linked immunosorbent assay. Despite exceptionally heavy blooms of toxic Nodularia in the Baltic Sea during the summer of 1997, Baltic herring and salmon contained very low quantities of nodularin and microcystins (2.5–6.5 ng g–1 dry weight, not corrected for recovery, [30%]). These concentrations do not pose a health threat to humans, based on the World Health Organization value of tolerable daily intake. Moreover, the concentrations we found in salmon and herring were much lower than those reported for livers of European flounder (Platichthys flesus L.) or Atlantic cod (Gadus morhua L.) from the Baltic Sea during 1996–1999. We suspect that cyanobacterial hepatotoxins do not effectively accumulate in herring and salmon.

Toxins in the freshwater cyanobacterium Cylindrospermopsis raciborskii (Cyanophyceae) isolated from Tabocas reservoir in Caruaru, Brazil, including demonstration of a new saxitoxin analogue

Cyanobacteria can produce biotoxins that are significant hazards to humans. After the intoxication incident in 1996 at the city of Caruaru, Brazil, a phytoplankton-monitoring programme was established at its main water supply, the Tabocas reservoir. Data obtained during 1997 and 1998 revealed the dominant species at Tabocas to be Cylindrospermopsis raciborskii, which was responsible for a massive bloom observed in July–October 1998. Laboratory cultures of isolate ITEP-018 demonstrated highly toxic properties, mice inoculated with this strain exhibited the same symptoms as those of paralytic shellfish poisoning, with an acute lethal effect of 9.3 mouse units mg−1 of dry cells. Several saxitoxin analogues were identified in these cultures, specifically saxitoxin (3.3 mol% total toxin content), gonyautoxin 6 (6.4 mol%), decarbamoyl-saxitoxin (8.5 mol%), neosaxitoxin (17.1 mol%), and a new saxitoxin analogue, which proved to be the major product of the Tabocas strain, accounting for 64.6 mol% of the toxin present in the sample analysed. Additionally, decarbamoylneo-saxitoxin was detected by liquid chromatography-mass spectrometry. Cylindrospermopsis raciborskii strain ITEP-018 thus produces at least five saxitoxin analogues, including the most toxic ones as assessed by mouse bioassay.

Accumulation and transformation of DSP toxins in mussels Mytilus galloprovincialis during a toxic episode caused by Dinophysis acuminata

The time course of several outbreaks of the diarrhetic shellfish poisoning (DSP) producer Dinophysis acuminata and the consequent kinetic of accumulation and loss of toxins in mussels Mytilus galloprovincialis feeding on them was studied. Samples of mussels and seawater were frequently (2–3 times a week) collected from a raft in the Rı́a de Vigo. DSP toxins content of mussels and water was analyzed by HPLC-FD and phytoplankton was quantified in an inverted light microscope. Only okadaic acid (OA) and some of its conjugated forms (OA CF), estimated by enzymatic hydrolysis, were found in the plankton samples obtained, comprised mainly of D. acuminata cells. The main accumulated form in mussels was OA reaching a maximum of 10.1 μg OA g −1 in the digestive gland (d.g.) in 16 days, falling below the quarantine level (ca. 2 μg OA g −1 d.g.) by 45 days. The low polarity conjugated forms (LPCF), estimated by hexane extraction, accounted for 6.2% of the total toxin burden of the mussels. To quantify the rates of the processes involved in the accumulation, transformation and loss of the toxins, two dynamic models, a one-compartment and a two-compartment, including OA and its conjugated forms as variables were designed and implemented. The one-compartment model provided a good fit to the OA and LPCF actual data ( r 2=0.92 and r 2=0.94, respectively). The two-compartment model did not fit the data markedly better than its one-compartment counterpart ( r 2=0.93 and r 2=0.95, for OA and LPCF, respectively). High hydrolysis rates were estimated for most of the OA CF, which means that these forms came largely from the ingested plankton. The low estimated acylation rates support the previous point and suggest that the formation of LPCF by direct acylation of the OA is of little importance in M. galloprovincialis. Only in cases where the intoxication period is very long, can the formed acyl-derivatives be important, because they seem to accumulate for a long time in the mussels, as suggested by the low hydrolysis and depuration rates estimated from model fitting.

Total dust, respirable dust, and microflora toxin concentrations in Colorado corn storage facilities.

To aid in the process of characterizing corn dust exposures on farms and in elevators in northeastern Colorado, several parameters were examined. Total dust and respirable dust samples were collected and evaluated. Potentially dangerous dust components evaluated were respirable silica, endotoxin, and mycotoxin levels. Many of the total dust samples (58%) would have exceeded 8-hour time-weighted average (TWA) had sampling been conducted for 8 hours; on farms the operation takes between two and four hours. The same statement may be made for respirable dust samples collected for this project. Nearly 33 percent of the respirable dust samples collected would have exceeded the Occupational Safety and Health Administration (OSHA) TWA had sampling been conducted over an 8-hour period. Respirable silica standards were exceeded at 25 percent of the sampling locations. Presence of mycotoxins at all sites was confirmed by the use of ELISA kits. The most significant finding of this study was high levels of endotoxin at several of the sampling sites. Eighty-five percent of the sampling locations had endotoxin levels above 500 EU/m3. One location, Farm 4, had endotoxin levels of above 1.7 million EU/m3.

Toxin production in migrating dinoflagellates: a modelling study of PSP producing Alexandrium

A mechanistic model of dinoflagellate physiology, previously developed and parameterised to simulate paralytic shellfish poison (PSP) content and cell growth for Alexandrium fundyense in response to N and P nutrition, was operated within a vertical water structure in which the organism migrated. Simulations showed the expected development of vertical migration behaviour in response to light and mineral nutrient interactions. Growth in a N-limited water column resulted in a continual, though low level, PSP production with a large population biomass. A sequence of P-stress and nutrient re-feeding during vertical migration stimulated an enhancement of PSP content even with only moderately elevated supply of N:P ratios. This was exacerbated by low absolute P concentrations below the nutricline as well as by the N:P ratio. Although the final biomass was lower in these P-limited simulations, the total toxin production was much higher. The simulations suggest that vertical migration in stratified waters in even moderately high N:P waters could result in the formation of highly toxic populations of Alexandrium. One may expect a similar enhancement of toxicity in other harmful algal species that are engaged in vertical migration, where nutrient supply ratios affect toxin production.

Isolation of Prorocentrum lima (Syn. Exuviaella lima) and diarrhetic shellfish poisoning (DSP) risk assessment in the Gulf of California, Mexico

A benthic toxic dinoflagellate identified as Prorocentrum lima (Syn. Exuviaella lima), and designated as strain PRL-1, was isolated from the coast of El Pardito (Coyote) Island in Baja California Sur, Mexico, after a fisherman poisoning incident involving consumption of liver from Lutjanus colorado, and Mycteroperca prionura fish. Purification and culturing was done in ES-Si medium, under 12:12 light/dark cycle (4×20 W cool-white fluorescent lamps), at 22 °C and constant stirring during 28 days. Whole cells were toxic to Artemia franciscana and its methanolic extract to mouse and to the marine yeast Debaryomyces hansenii. Chromatographic analysis (TLC and HPLC–MS) of such extract indicated an unusual proportion (1:2) okadaic acid (OA) and dinophysistoxin-1 (DTX-1). Estimated total toxin content by mouse bioassay (based on OA toxicity) was 19 pg/cell, a value significantly higher than that found by HPLC–MS (about 5.2 pg/cell, taking into account OA and DTX-1 only), suggesting that additional toxic components of unidentified nature are detected with the bioassay. This is the first report of a successful isolation and culturing of a toxic dinoflagellate from the Gulf of California, Mexico.

A tárolási feltételek hatása a kukorica Fusarium fertőzöttségére és toxin szennyezettségére

Corn samples harvested in 1997, 1998 and 1999 from different soil types were stored at different conditions (temperature, moisture content, state of kernels) for six months. The Fusarium contamination was examined by plate dilution method and the amount of mycotoxins (F-2, T-2, HT-2, DON, DAS) were determined applying HPLC method immediately after harvesting and in the third and sixth month of storage. The aim of our study was to find correlation between the ecological factors, storage conditions and the examined parameters mentioned above, as well as to prove them statistically. According to the examinations carried out after harvesting we could state that the soil type had no effect on the parameters. Analysing the effect of the years we found considerable differences. The Fusarium infection of corn samples in 1998, while the toxin contamination in 1999 was the highest. The results of storage experiment show that year (number of microscopic fungi, F-2, T-2, HT-2, DAS and total toxin content) and moisture content of kernels (F-2, T-2, and total toxin content) have a significant effect on the examined parameters. We could prove the effect of temperature on the T-2 content (samples with natural moisture content) and DON content (samples with 14% moisture content). Higher values were found at higher temperature storage. The ratio of damaged kernels influenced the DON concentration in the non- wetted samples and the number of microscopic fungi in the wetted samples.

A study of spatial variability of domoic acid in razor clams: recommendations for resource management on the Washington coast

Domoic acid (DA) levels in Washington State razor clams ( Siliqua patula) have been extremely variable and unpredictable, resulting in emergency closures of harvest areas in 1991, 1998, and 1999. Information concerning toxin variability relative to sampling location is important in developing a more reliable plan for managing DA outbreaks. In November 1998, record levels of DA in razor clams (up to 295 ppm) were reported at Kalaloch beach, Washington. A razor clam resource survey conducted there during the summer of 1999, along with the long retention time of DA in the clams, permitted a study of DA levels as a function of tidal elevation and north-south beach location. During the summer low tides (28–31 July 1999) razor clams were collected from six east-west transects, approximately 1.6 km apart. Each clam was individually analyzed for DA to determine the distribution of toxin between (interspecific variability) and within (intraspecific variability) transects. While average DA levels were similar between transects, toxin levels varied substantially among individual clams. The coefficient of variation among all samples ( n=445) was 122%, indicating that harvest closures based upon composite analyses of only six clams could be in error. Here we recommend a sampling strategy of razor clams for regulatory purposes that will result in DA measurements more representative of total population toxin values.