An amyotrophic lateral sclerosis hot spot in the French Alps associated with genotoxic fungi

Between 1990 and 2018, 14 cases of amyotrophic lateral sclerosis (ALS) were diagnosed in residents of, and in visitors with second homes to, a mountainous hamlet in the French Alps. Systematic investigation revealed a socio-professional network that connected ALS cases. Genetic risk factors for ALS were excluded. Several known environmental factors were scrutinized and eliminated, notably lead and other chemical contaminants in soil, water or home-grown vegetation used for food, radon and electromagnetic fields. Some lifestyle-related behavioral risk factors were identified: Prior to clinical onset of motor neuron disease, some patients had a high degree of athleticism and smoked tobacco. Recent investigations on site, based on a new hypothesis, showed that all patients had ingested wild mushrooms, notably poisonous False Morels. Half of the ALS cohort reported acute illness following Gyromitra gigas mushroom consumption. This finding supports the hypothesis that genotoxins of fungal origin may induce motor neuron degeneration.

Enumeration of Probiotic Pediococci in Animal Feed: Interlaboratory Study

An enumeration method to be used as official control under Council Directive 70/524/EEC for probiotic pediococci used as feed additives was validated for consideration for adoption as Comitée Européen de Normalisation (CEN) and ISO standards. Seventeen laboratories in 11 European countries carried out an interlaboratory study. A spread plate method following BS ISO 15214:1998 using 4 different agars [MRS, acidified MRS, MRS with triphenyl tetrazolium chloride (TTC), and a newly developed pediococci selective medium (PSM)] was validated. Precision data in terms of repeatability (r) and reproducibility (R) of the method for each medium using different feeding stuffs with a high and a low inoculation level were determined. Pediococci were present in the samples in mixtures with other probiotics. The enumeration of pediococci on all agars showedan RSDr value of 0.4–3.1% and an RSDR of 1.3–4.8%. MRS agar was preferred, followed by acidified MRS and MRS + TTC agar. All 4 media gave similar counts. Depending on the presence and concentration of other probiotic, such as enterococci, lactobacilli, and yeast, acidified MRS or MRS + TTC agar are recommended. The PSM was selective for pediococci and can be used if this species is present at a concentration more than 10-fold lower than other species that can grow on the MRS agars. The methodology with all 4 media is not applicable to mineral feed.

Usefulness of FTIR spectroscopy to distinguish rough and smooth variants of Lactobacillus farciminis CNCM-I-3699

In this study, the potential of Fourier transform infrared (FTIR) spectroscopy for assessing putative biochemical and structural differences between the two variants, rough (R) and smooth (S), of Lactobacillus farciminis CNCM-I-3699, a pleomorphic strain, was investigated. The main differences observed were localized in the polysaccharide (1200-900 cm-1) and protein (1700-1500 cm-1) regions. Based on spectral information in these two spectral ranges, clustering resulted in a dendrogram that showed a clear discrimination between both morphotypes. Significant increases in favor of morphotype S compared to R at specific wavenumbers for polysaccharides (22.18% vs. 5.24% at 1068 cm-1) and capsular polysaccharides (16% vs. 13.17% at 1048 cm-1) were recorded. Compared to S, the morphotype R exhibits a 1.27-fold higher signal at the wavenumber of 1637 cm-1 assigned to the amide I β-sheet and a 2.71-fold higher signal at the wavenumber of 1513 cm-1 assigned to the tyrosine involved in the β-sheet arrangement of proteins. The FTIR analysis is efficient to separate and give data on mainly surface component differences observed previously between S colony morphotype (ropy and exopolysaccharide positive) and the R colony morphotype (non-ropy but highly autoaggregative).

[Evaluation of Antilles fish ciguatoxicity by mouse and chick bioassays]

Ciguatera is a common seafood poisoning in Western Atlantic and French West Indies. Ciguatera fish poisoning in the Caribbean is a public health problem. A toxicological study was carried out on 178 Caribbean fish specimens (26 species) captured off Guadeloupe and Saint Barthelemy between 1993 and 1999. The mouse bioassay and the chick feeding test were used to control fish edibility. Ciguatoxins presence was assumed when symptomatology was typical of ciguatera in mouse and chick. Fishes were classified in three groups: non toxic fish (edible), low toxic fish (not edible) and toxic fish (not edible). 75% of fishes were non toxic. Toxic fish specimens belonged to four families of high trophic level carnivores: Carangidae, Lutjanidae, Serranidae et Sphyraenidae. Percentages of toxic fishes to humans reached 55% for Caranx latus and 33% for Caranx bartholomaei and Caranx lugubris. Only a significant correlation between weight and toxicity was only found for C. latus and snappers. Small carnivorous groupers (Serranidae) were also toxic. Atoxic fish species were (a) pelagic fish (Coryphaena hippurus, Auxis thazard and Euthynnus pelamis), (b) invertebrates feeders (Malacanthus plumieri, Balistes vetula), (c) small high-risk fish or (d) fish of edible benthic fish families. Liver of four fishes (Mycteroperca venenosa, Caranx bartholomaei, Seriola rivoliana, Gymnothorax funebris) contained ciguatoxins at a significant level although their flesh was safe. This study confirms the usefulness of mouse and chick bioassays for sanitary control of fish.

Analysis of toxin profiles in three different fish species causing ciguatera fish poisoning in Guadeloupe, French West Indies

A grey snapper (Lutjanus griseus), a grouper (Serranidae) and a black jack (Caranx lugubris) were implicated in three different ciguatera poisonings in Guadeloupe, French West Indies. A mouse bioassay indicated toxicity for each specimens: 0.5-1, > or = 1 and > 1 MUg g(-1), respectively. After purification by gel filtration chromatography, the samples were analysed by high-performance liquid chromatography coupled to mass spectrometry (LC-MS). The toxin profiles differ from one fish to another. C-CTX-1 was detected at 0.24, 0.90 and 13.8 ng g(-1) flesh in the snapper, grouper and jack, respectively. It contributed only to part of the whole toxicity determined by the mouse bioassay. Other toxins identified were C-CTX-2 (a C-CTX-1 epimer), three additional isomers of C-CTX-1 or-2, and five ciguatoxin congeners (C-CTX-1127, C-CTX-1143 and its isomer C-CTX-1143a, and C-CTX-1157 and its isomer C-CTX-1157b). Putative hydroxy-polyether-like compounds were also detected in the flesh of the grouper with [M+ + H]+ ions at m/z 851.51, 857.50, 875.51, 875.49 and 895.54 Da. Some of these compounds have the same mass range as some known dinoflagellate toxins. In conclusion, this study confirms the usefulness of LC-MS analysis to determine the ciguatoxins levels and the toxin profile in fish flesh hazardous to humans.

Usefulness of epifluorescence for quantitative analysis of lactobacilli in probiotic feed

AIMS

Enumeration of total, active or viable probiotic micro-organisms from liquid or solid commercial feedstuffs was studied during processing and storage.

METHODS AND RESULTS

After sample preparation, an epifluorescence microscopy technique and a plating method were investigated comparatively. It was shown that (i) on the day of manufacture, active or viable bacteria were in equivalent amounts and that viable numbers then decreased, depending on the different processing and storage factors enhancing ABNC production, (ii) the amount of total and active lactobacilli remained close and quite stable for months at a high level (>10(8) active fluorescent units).

CONCLUSIONS

Processing and storage promoted ABNC cells in the products tested. Consequently, both techniques should be used to evaluate the viable-dead-active status of bacteria for which functional properties are claimed.

SIGNIFICANCE AND IMPACT OF THE STUDY

Enumeration of the whole probiotic bacterial population should be take into account for guidelines and labelling since non-viable bacteria could have a probiotic effect.

Ciguatera fish poisoning in the Caribbean islands and Western Atlantic

Ciguatera fish poisoning (ciguatera), a common poisoning caused by fish ingestion, is reviewed in the Western Atlantic and the Caribbean waters. It is endemic from Florida coasts (northern limit) to Martinique Island (southern limit), with outbreaks occurring from time to time. In the Caribbean, ciguatera causes a polymorphic syndrome with gastrointestinal, cardiovascular, and neurological signs and symptoms. Neurological and muscular dysfunctions can be treated by intravenous injection of D-mannitol. The lipid-soluble toxins involved are ciguatoxins that are likely produced by the dinoflagellate Gambierdiscus toxicus. G. toxicus strains are endemic in the Caribbean Sea and in theWestern Atlantic. Although it is likely that blooms of G. toxicus are ingested by herbivorous fishes, they are not implicated in ciguatera in the Caribbean. Rather, large carnivores (barracudas, jacks, snappers, groupers), consumers of smaller benthic fish, are often involved in ciguatera. Fish toxicity depends on fishing area and depth, fish size and tissues, and climatic disturbances. Ciguatoxins have been isolated and purified from Caribbean fish species. The structure of two epimers, C-CTX-1 and C-CTX-2 from horse-eye jack, comprise 14 trans-fused ether-linked rings and a hemiketal in terminal ring. Caribbean ciguatoxins are mainly detected in the laboratory by chicken, mouse, mosquito, or cell bioassays, and by analytical HPLC/tandem mass spectrometry down to parts per billion (ppb). A ciguatera management plan that integrates epidemiology, treatment, and a simple method of detection is required to ensure the protection of consumers.

HPLC/tandem electrospray mass spectrometry for the determination of Sub-ppb levels of Pacific and Caribbean ciguatoxins in crude extracts of fish

Ciguatera is a significant food-borne disease caused by potent polyether toxins (ciguatoxins) which accumulate in the flesh of ciguateric reef fish at risk levels > 0.1 ppb for Pacific ciguatoxins. Research on ciguatera has been severely hindered by the lack of analytical methods that detect and characterize low levels of ciguatoxin in crude extracts of fish. Here we report a new procedure for ciguatoxin analysis based on gradient reversed-phase HPLC/tandem mass spectrometry (HPLC/MS/MS). The method gave a linear response to pure Pacific and Caribbean ciguatoxins (P-CTX-1 and C-CTX-1) and the structurally related brevetoxin (PbTx-2) spiked into crude extracts of fish. Levels equivalent to 40 ppt P-CTX-1, 100 ppt C-CTX-1, and 200 ppt PbTx-2 in fish flesh could be detected by HPLC/MS/MS. Using P-CTX-1 as an internal standard, the analysis of extracts of 30 ciguateric fish from the Caribbean Sea (8 toxic, 12 borderline, and 10 nontoxic by mouse bioassay) confirmed the reliability of the method and allowed an estimated risk level of > 0.25 ppb C-CTX-1 to be established. HPLC/MS/MS provides a sensitive analytical approach, not previously available, for the determination of Pacific and Caribbean ciguatoxins at sub-ppb levels in fish flesh.

Isolation and characterisation of Caribbean ciguatoxins from the horse-eye jack (Caranx latus)

The toxins involved in ciguatera (fish poisoning) in the Caribbean Sea were isolated from Caranx latus, a pelagic fish often implicated in ciguatera in the Caribbean region, and purified by mouse bioassay directed fractionation. Five toxins were separated by reverse-phase high-performance liquid chromatography (HPLC). In order of increasing hydrophobicity, these toxins included a sleep-inducing fraction (< 1% of total toxicity), a major Caribbean ciguatoxin (C-CTX-1, 65% of toxicity), a minor Caribbean ciguatoxin (C-CTX-2, 13% of toxicity), a minor toxin (approximately 1% of toxicity) and a hydrophobic, fast-acting toxin (approximately 19% of toxicity). The i.p. injection into mice of each toxin induced signs typical of site-5 sodium channel activator toxins such as the Pacific ciguatoxins and brevetoxins. C-CTX-1 and C-CTX-2 were purified to homogeneity (LD50 = 3.6 and approximately 1 microgram/kg, respectively) and subjected to ion spray mass spectrometry. Both lost up to five H2O molecules and each had a [M+H]+ ion, m/z 1141.7, suggesting that C-CTX-1 and -2 are diastereomers that differ from the Pacific family of ciguatoxins. Turbo-assisted HPLC-mass spectrometry identified C-CTX-1, C-CTX-2 and three C-CTX-1-related compounds in an enriched fraction but no Pacific ciguatoxins were detected. The presence of different families of ciguatoxins in ciguateric fish from the Caribbean Sea and Pacific Ocean probably underlies the clinical differences in the ciguatera syndrome reported in these two regions. A Caribbean strain of the benthic dinoflagellate, Gambierdiscus toxicus, is suspected as source of these ciguatoxins. The extent to which these toxins are biotransformed as they pass through the marine food chain remains to be determined.

Effect of an unknown toxin isolated from Dinophysis sp.-contaminated French mussels, on the electrical and mechanical activity of frog heart

The effects of an unknown toxin, isolated along with okadaic acid from the hepatopancreas of French mussels contaminated by Dinophysis sp., producing ataxia, neurologic symptoms, bradycardia, arrhythmias, electrocardiographic changes, and cardiac arrest, have been studied in terms of the electrical and mechanical activity of frog atrial heart muscle. The toxin, in a dose-dependent manner, decreased the amplitude of the stimulated peak tension of isolated fibers. The toxin (1-36 micrograms/ml) did not modify the membrane resting potential but decreased the amplitude of the plateau and shortened the duration of the action potential. The toxin inhibited the Cd-sensitive L-type Ca current and increased a 4-aminopyridine-sensitive outward current in voltage-clamped cardiac myocytes. The data show that the cardiac effect of the toxin is markedly different from that of okadaic acid.

Highly sensitive assay of okadaic acid using protein phosphatase and paranitrophenyl phosphate

A colorimetric phosphatase-inhibition bioassay was developed for the quantitative measurement of okadaic acid (OA) the main diarrhetic toxin responsible for diarrhetic shellfish poisoning. The assay used an artificial substrate, paranitrophenylphosphate, and a semi-purified protein phosphatase PP2Ac containing extract prepared from rabbit muscle. Calibration dose-inhibition curves were constructed using standard OA and they permitted easy determination of the enzyme concentration Et in their linear portion. In the range of linearity, the slope increased when Et decreased, thus giving a detecting limit of 0.04 pmol in the reaction mixture (1 ml). The lowest assayable concentration of OA was 4 ng/ml in aqueous solutions and 40 ng/ml (i.e., 100 ng of OA per g of mussel tissue) in crude methanol mussels extracts. The intra and interassay coefficients of variation in the measurement of OA for the toxin spiked aqueous samples averaged, respectively, 7.7% and 3.7%, and interexperiments coefficients of variation for the toxin spiked mussel extracts averaged 4.6%. The presence of OA was ascertained by a method in which one assay was performed at two or three different levels of enzyme concentration. The rapidity, accuracy, reproducibility, specificity, and simplicity of the procedure provides a simple way to assay okadaic acid in buffered or complex solutions.

Studies on the detection of okadaic acid in mussels: preliminary comparison of bioassays

Diarrheic toxins, especially okadaic acid, are detected nearly every year in mussels on French coasts. The monitoring network determines the toxicity of these shellfish by using a mouse test now considered unsatisfactory from an ethical point of view. Two alternative methods have been investigated: the daphnia test, for which there is a standardized method used routinely in ecotoxicology, and a cytotoxicity test on the KB cell line developed for this study. Using the same samples, the results of these two tests were compared with those obtained by chemical analysis (HPLC okadaic acid assay) or the mouse test. Linear regression studies showed that results for the two bioassays were well correlated with those for HPLC or the mouse test.

Cooked mussels contaminated by Dinophysis sp.: a source of okadaic acid

A method was developed for fractionation and isolation of toxic components present in extracts prepared from Dinophysis-contaminated mussels. The major toxin present in French mussels was identified as okadaic acid by its chromatographic properties and spectral data. Large amounts of mussel tissue (digestive glands and remaining meat) can be treated easily if they are cooked, or cooked and dried and are useful for isolating significant amounts of okadaic acid.

The use of Daphnia magna for detection of okadaic acid in mussel extracts

Okadaic acid (OA), the main toxin responsible for diarrheic shellfish poisoning (DSP) has toxicity for Daphnia magna (EC50 = 15 +/- 1.8 micrograms/l). A Daphnia bioassay was developed and used to analyse okadaic acid in mussel extracts. A linear correlation was found between OA concentration determined by the Daphnia bioassay and by HPLC assay (r = 0.85; p < 0.001). The Daphnia bioassay can measure OA levels 10 times below the threshold of the mouse bioassay method. It is an inexpensive sensitive tool which can be used in replacement of mouse bioassay for the screening of OA and some co-extracting toxins in mussel extracts.

Fractionation and purification of some muscular and visceral ciguatoxins extracted from Carribean fish

1. Cigautoxins (CTX) were extracted from flesh and viscera of seven large roving predatory fishes: Caranx bartholomaei, Caranx latus, Seriola dumerili, Alectis crinitus, Scomberomorus cavalla, Sphyraena barracuda and Gymnothorax funebris. 2. Generally each extract consisted of close-related CTX which were separated according to their polarity by Florisil column chromatography into a fast-acting CTX containing group and a slow-acting CTX containing group. 3. The shortest survival time of mice (ts) was low for the former group (less than 10 min) and high for the latter (greater than or equal to 29 min). 4. The level of purity had no influence on the range of ts values. The presence of these two CTX groups in different extracts did not from experimental conditions. 5. Attempts to convert fast-acting CTX to slow-acting CTX and vice-versa were negative. G. funebris and S. barracuda had an especially high content of unstable fast-acting CTX. 6. Purification of the slow-acting CTX was achieved by fast elution chromatography and Sephadex LH20 gel filtration. 7. The ts values of these CTX were identical for five species (40-44 min) but not for S. barracuda (29-32 min). 8. Thus ciguatoxic extracts from Caribbean fish were composed of several close-related CTX.

[Heterogeneity of ciguatoxins extracted from fish caught in the French Antilles]

Ciguatoxin-like substances were extracted from the viscera or the flesh of eight Caribbean fish species, including small invertebrate feeders and large carnivores. The had similar properties, i.e. pharmacological action, solubility, chromatographic behaviour on silicic acid or Sephadex LH 20 column, stability in a weak acid solution and instability in alkaline medium. However, Florisil column and thin-layer chromatography showed different ciguatoxins whose number depended on tissue or species but not on fish trophic level. Less polar ciguatoxins appeared in salted and dried flesh. Thus, fish ciguatoxins are believed to be closely related substances, possibly changing in structure according to particular experimental conditions.

A study of the distribution of ciguatoxin in individual Caribbean fish

Ciguatera toxins were extracted from the tissues of 36 poisonous fishes including 9 dangerous species collected in the Caribbean. Toxicity assays were carried out in mice and the distinctive symptoms of ciguatera poisoning were observed. In a single fish, ciguatoxin was found in the blood, flesh, gonads, gills, heart, skin and bones. The concentration was highest in the viscera and in particular in the liver, kidney and spleen. The ratios of the toxin concentrations of the liver or viscera to that of the flesh were high and varied with the species suggesting that the toxin is stored in different ways in different fish. Subcellular fractionation of liver cells revealed that most of the ciguatoxin was attached to cytoplasmic proteins and that some toxin was probably bound to the membranes.

Chick feeding test: a simple system to detect ciguatoxin

Chick poisoning induced by oral administration of toxic fish tissues or extracts gave rise to internal hypersalivation, decrease in weight and acute motor ataxia. Detoxification was low and repeated administration therefore led to toxin accumulation. Response of the chicken to liver feeding was roughly quantitative; so liver, which is the most potential toxic tissue, may be used for a preventive screening test in ciguatera-endemic areas.

[Demonstration of a liposoluble ciguateric toxin in Caranx bartholomaei caught in the French West Indies]

This report deals with some of the biological and chemical properties of a liposoluble poison extracted from Caranx bartholomaei (yellow jack), a toxic fish from the French West Indies (St Barth's island). Within a single fish, poison concentration is higher in the viscera; toxicity level is uniform throughout the flesh. In the few specimens tested, liver toxicity variations parallel those of flesh. The poison is heat stable so that cooking does not impair the toxicity. It is soluble in acetone, diethyl ether, chloroform, benzene, methanol and ethanol, but insoluble in n. hexane. Crude toxin injection or ingestion induces ciguateric disease in cats, mice or newly born chicken. Crude toxin stability is good after 30 minutes at 90 degrees C in a 0,5 N solution of a weak acid but not of a weak base. In the same conditions, loss of activity is nearly complete with a strong acid or a strong base. Moreover, rapid alkali treatment at room temperature destroys more than 50 per cent of the toxicity. The toxin is eluted by chloroform-methanol (9:1) from a silicic acid column and by acetone-methanol (9,5:0,5) from a Florisil column. DEAE cellulose column chromatography clearly separates the toxin into two lethal components; but thin layer chromatography of crude or fractionated toxin indicates only one toxic band in three different solvent systems. As a conclusion, in spite of a few differences related to instability in alkalin medium and elution from DEAE cellulose, this poison is quite similar to those carried by ciguatoxic fishes from the Pacific area. The differences noted above could be accounted for either by a specific metabolism of the species studied or by differences in the causative agent due to geographical location, or both.

[Fractionation of ciguatoxic lipid extracts in alkaline medium]

A modification of the extraction procedure for obtaining ciguatoxic substances from the tissues of various poisonous reef fish has been developed. Rapid alkali treatment of the residue obtained at an early stage is efficient in separating the ciguatoxic fraction from toxic impurities which interfere with pharmacological tests. It is thus possibles to carry out a more precise dosage of the material separated in this way. Alkali treatment does not affect either the physiological activity in cats and mice of the ciguatoxic substances nor their behaviour in a preparative thin layer chromatography in a benzene-butanol system.

[Comparative immunological study of protein extracts of poisonous and non-poisonous fishes (author's transl)]

Suggesting an immunologic participation in the pathogeny of the ciguateric syndroms, the authors have prepared a proteic antigen from the flesh of poisonous and edible fish of the same species. They have shown that there is a total common antigenicity between toxic and non toxic extracts. They suggest a new immunologic approach, in the matter of intoxication by ciguateric fish.

[The absence of Sindbis virus from French Polynesia]

The authors report, in French Polynesia that Sindbis antigen is a good control for rubella serodiagnosis. Data are presented on Hemagglutination Inhibition from 2,032 sera, showing no evidence of any Sindbis antigen circulation.

[Ciguatoxin and edible reef fishes]

Referring to the various human and animal clinical response to consumption of reef fish, the authors precise the importance of ingested dose and the role of cumulative effects. They point out the arbitrary character of distinguishing poisonous and edible fish of the same species. At the light of these data they find ciguatoxin in edible fish from known latent ciguateric potential species in atoxic areas. Therefore ciguatoxin does appear as a natural biotoxin permanently produced in most of the polynesian coral reefs ecosystems. The occurence of clinical disorders by men and animals results from a sudden increase of its production following biological transitory modification of some coral reef biota.