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Toxins, Volume 9, Issue 5 (May 2017)

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Cover Story Venom from the African tarantula Monocentropus balfouri was found to contain two insecticidal [...] Read more.
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Editorial

Jump to: Research, Review

Open AccessEditorial An Introduction to the Toxins Special Issue on “Novel Pharmacological Inhibitors for Bacterial Protein Toxins”
Toxins 2017, 9(5), 160; doi:10.3390/toxins9050160
Received: 9 May 2017 / Revised: 9 May 2017 / Accepted: 10 May 2017 / Published: 11 May 2017
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Open AccessEditorial “Uremic Toxin” Section in the Journal Toxins: A Powerful Tool to Bundle and Advance Knowledge on Uremia
Toxins 2017, 9(5), 170; doi:10.3390/toxins9050170
Received: 12 May 2017 / Revised: 15 May 2017 / Accepted: 15 May 2017 / Published: 18 May 2017
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(This article belongs to the Section Uremic Toxins)

Research

Jump to: Editorial, Review

Open AccessArticle Assessing the Efficacy of First-Aid Measures in Physalia sp. Envenomation, Using Solution- and Blood Agarose-Based Models
Toxins 2017, 9(5), 149; doi:10.3390/toxins9050149
Received: 20 March 2017 / Revised: 18 April 2017 / Accepted: 21 April 2017 / Published: 26 April 2017
Cited by 1 | PDF Full-text (2868 KB) | HTML Full-text | XML Full-text
Abstract
Stings from the hydrozoan species in the genus Physalia cause intense, immediate skin pain and elicit serious systemic effects. There has been much scientific debate about the most appropriate first aid for these stings, particularly with regard to whether vinegar use is appropriate
[...] Read more.
Stings from the hydrozoan species in the genus Physalia cause intense, immediate skin pain and elicit serious systemic effects. There has been much scientific debate about the most appropriate first aid for these stings, particularly with regard to whether vinegar use is appropriate (most current recommendations recommend against vinegar). We found that only a small percentage (≤1.0%) of tentacle cnidae discharge during a sting event using an ex vivo tissue model which elicits spontaneous stinging from live cnidarian tentacles. We then tested a variety of rinse solutions on both Atlantic and Pacific Physalia species to determine if they elicit cnidae discharge, further investigating any that did not cause immediate significant discharge to determine if they are able to inhibit cnidae discharge in response to chemical and physical stimuli. We found commercially available vinegars, as well as the recently developed Sting No More® Spray, were the most effective rinse solutions, as they irreversibly inhibited cnidae discharge. However, even slight dilution of vinegar reduced its protective effects. Alcohols and folk remedies, such as urine, baking soda and shaving cream, caused varying amounts of immediate cnidae discharge and failed to inhibit further discharge, and thus likely worsen stings. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessArticle Cytotoxic Indole Alkaloid 3α-Acetonyltabersonine Induces Glioblastoma Apoptosis via Inhibition of DNA Damage Repair
Toxins 2017, 9(5), 150; doi:10.3390/toxins9050150
Received: 5 March 2017 / Revised: 16 April 2017 / Accepted: 19 April 2017 / Published: 28 April 2017
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Abstract
Cytotoxic indole alkaloids from Melodinus suaveolens, which belongs to the toxic plant family Apocynaceae, demonstrated impressive antitumor activities in many tumor types, but less application in glioblastoma, which is the lethal brain tumor. In the present study, we reported the anti-glioblastoma activity
[...] Read more.
Cytotoxic indole alkaloids from Melodinus suaveolens, which belongs to the toxic plant family Apocynaceae, demonstrated impressive antitumor activities in many tumor types, but less application in glioblastoma, which is the lethal brain tumor. In the present study, we reported the anti-glioblastoma activity of an indole alkaloid, 3α-acetonyltabersonine, which was isolated from Melodinus suaveolens. 3α-acetonyltabersonine was cytotoxic to glioblastoma cell lines (U87 and T98G) and stem cells at low concentrations. We verified 3α-acetonyltabersonine could suppress tumor cell proliferation and cause apoptosis in glioblastoma stem cells (GSCs). Moreover, detailed investigation of transcriptome study and Western blotting analysis indicated the mitogen activated protein kinase (MAPK) pathway was activated by phosphorylation upon 3α-acetonyltabersonine treatment. Additionally, we found 3α-acetonyltabersonine inhibited DNA damage repair procedures, the accumulated DNA damage stimulated activation of MAPK pathway and, finally, induced apoptosis. Further evidence was consistently obtained from vivo experiments on glioblastoma mouse model: treatment of 3α-acetonyltabersonine could exert pro-apoptotic function and prolong the life span of tumor-bearing mice. These results in vitro and in vivo suggested that 3α-acetonyltabersonine could be a potential candidate antitumor agent. Full article
(This article belongs to the Section Plant Toxins)
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Open AccessArticle Development of an Immunochromatographic Strip Test for the Rapid Detection of Alternariol Monomethyl Ether in Fruit
Toxins 2017, 9(5), 152; doi:10.3390/toxins9050152
Received: 30 March 2017 / Revised: 21 April 2017 / Accepted: 22 April 2017 / Published: 29 April 2017
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Abstract
A rapid, portable, and semi-quantitative immunochromatographic strip was developed for rapid and visual detection of alternariol monomethyl ether (AME). For this purpose, the anti-AME monoclonal antibody (mAb) was prepared and identified. AME coupled to bovine serum albumin (BSA) via methyl 4-bromobutanoate was prepared
[...] Read more.
A rapid, portable, and semi-quantitative immunochromatographic strip was developed for rapid and visual detection of alternariol monomethyl ether (AME). For this purpose, the anti-AME monoclonal antibody (mAb) was prepared and identified. AME coupled to bovine serum albumin (BSA) via methyl 4-bromobutanoate was prepared as immunogen. The recoveries of AME in spiked cherry and orange fruits determined by competitive ELISA were 86.1% and 80.7%, respectively. A colloidal gold nanoparticle (CGN) and CGNs-mAb conjugate were synthesized, and on this basis, a competitive colloidal gold immunochromatographic strip was developed and applied to the detection of AME toxin in fruit samples. The intensity of red density of the test line (T line) is inversely proportional to AME concentration in the range 0.1–10 ng/mL. The visual limit of detection (LOD) of AME was found to be about 10 ng/mL. The semi-quantitative detection can be completed in 10 min. Moreover, the immunochromatographic strip has lower cross-reactivity with AME analogues, and it has a good stability performance (following 3 months of storage). Hence, the colloidal gold immunochromatographic strip could be used as a semi-quantitative tool for the on-site, rapid, and visual detection of AME in fruit. Full article
(This article belongs to the Section Mycotoxins)
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Open AccessArticle Distinct Expression of Immunoglobulin-Binding Proteins in Shiga Toxin-Producing Escherichia coli Implicates High Protein Stability and a Characteristic Phenotype
Toxins 2017, 9(5), 153; doi:10.3390/toxins9050153
Received: 28 February 2017 / Revised: 27 April 2017 / Accepted: 27 April 2017 / Published: 29 April 2017
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Abstract
Several immunoglobulin-binding proteins of Escherichia coli (Eib) have been isolated from both non-pathogenic and pathogenic E. coli strains. Shiga toxin (Stx)-producing E. coli (STEC) contain eibG either as a single gene or in combination with eibC, while other E. coli strains
[...] Read more.
Several immunoglobulin-binding proteins of Escherichia coli (Eib) have been isolated from both non-pathogenic and pathogenic E. coli strains. Shiga toxin (Stx)-producing E. coli (STEC) contain eibG either as a single gene or in combination with eibC, while other E. coli strains harbour single or multiple eib genes. The Eib proteins bind human immunoglobulins in a non-immune manner and contribute to bacterial chain-like adherence to human epithelial cells. In this study, the EibG expression in several STEC strains was analysed under different environmental conditions. STEC produced high levels of EibG in complex media and lower levels in low-grade and minimal media under static growth conditions. This characteristic was independent on the Eib subtypes. Microscopically, EibG-expressing STEC exhibited chain formation and aggregation in all employed media, while aggregates were only visible after growth in complex medium. Once expressed, EibG proteins demonstrate high stability during prolonged incubation. Our findings indicate that the regulation of the expression of Eib proteins is highly complex, although the protein levels vary among STEC strains. However, positive upregulation conditions generally result in distinct phenotypes of the isolates. Full article
(This article belongs to the Section Bacterial Toxins)
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Open AccessArticle New Disulfide-Stabilized Fold Provides Sea Anemone Peptide to Exhibit Both Antimicrobial and TRPA1 Potentiating Properties
Toxins 2017, 9(5), 154; doi:10.3390/toxins9050154
Received: 16 February 2017 / Revised: 27 April 2017 / Accepted: 27 April 2017 / Published: 29 April 2017
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Abstract
A novel bioactive peptide named τ-AnmTx Ueq 12-1 (short name Ueq 12-1) was isolated and characterized from the sea anemone Urticina eques. Ueq 12-1 is unique among the variety of known sea anemone peptides in terms of its primary and spatial structure. It
[...] Read more.
A novel bioactive peptide named τ-AnmTx Ueq 12-1 (short name Ueq 12-1) was isolated and characterized from the sea anemone Urticina eques. Ueq 12-1 is unique among the variety of known sea anemone peptides in terms of its primary and spatial structure. It consists of 45 amino acids including 10 cysteine residues with an unusual distribution and represents a new group of sea anemone peptides. The 3D structure of Ueq 12-1, determined by NMR spectroscopy, represents a new disulfide-stabilized fold partly similar to the defensin-like fold. Ueq 12-1 showed the dual activity of both a moderate antibacterial activity against Gram-positive bacteria and a potentiating activity on the transient receptor potential ankyrin 1 (TRPA1). Ueq 12-1 is a unique peptide potentiator of the TRPA1 receptor that produces analgesic and anti-inflammatory effects in vivo. The antinociceptive properties allow us to consider Ueq 12-1 as a potential analgesic drug lead with antibacterial properties. Full article
(This article belongs to the Section Marine and Freshwater Toxins)
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Open AccessFeature PaperArticle Insect-Active Toxins with Promiscuous Pharmacology from the African Theraphosid Spider Monocentropus balfouri
Toxins 2017, 9(5), 155; doi:10.3390/toxins9050155
Received: 28 March 2017 / Revised: 24 April 2017 / Accepted: 28 April 2017 / Published: 5 May 2017
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Abstract
Many chemical insecticides are becoming less efficacious due to rising resistance in pest species, which has created much interest in the development of new, eco-friendly bioinsecticides. Since insects are the primary prey of most spiders, their venoms are a rich source of insect-active
[...] Read more.
Many chemical insecticides are becoming less efficacious due to rising resistance in pest species, which has created much interest in the development of new, eco-friendly bioinsecticides. Since insects are the primary prey of most spiders, their venoms are a rich source of insect-active peptides that can be used as leads for new bioinsecticides or as tools to study molecular receptors that are insecticidal targets. In the present study, we isolated two insecticidal peptides, µ/ω-TRTX-Mb1a and -Mb1b, from venom of the African tarantula Monocentropus balfouri. Recombinant µ/ω-TRTX-Mb1a and -Mb1b paralyzed both Lucilia cuprina (Australian sheep blowfly) and Musca domestica (housefly), but neither peptide affected larvae of Helicoverpa armigera (cotton bollworms). Both peptides inhibited currents mediated by voltage-gated sodium (NaV) and calcium channels in Periplaneta americana (American cockroach) dorsal unpaired median neurons, and they also inhibited the cloned Blattella germanica (German cockroach) NaV channel (BgNaV1). An additional effect seen only with Mb1a on BgNaV1 was a delay in fast inactivation. Comparison of the NaV channel sequences of the tested insect species revealed that variations in the S1–S2 loops in the voltage sensor domains might underlie the differences in activity between different phyla. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessArticle Histopathological Effects of Bt and TcdA Insecticidal Proteins on the Midgut Epithelium of Western Corn Rootworm Larvae (Diabrotica virgifera virgifera)
Toxins 2017, 9(5), 156; doi:10.3390/toxins9050156
Received: 22 March 2017 / Revised: 20 April 2017 / Accepted: 28 April 2017 / Published: 8 May 2017
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Abstract
Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is a major corn pest in the United States, causing annual losses of over $1 billion. One approach to protect against crop loss by this insect is the use of transgenic corn hybrids expressing one
[...] Read more.
Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is a major corn pest in the United States, causing annual losses of over $1 billion. One approach to protect against crop loss by this insect is the use of transgenic corn hybrids expressing one or more crystal (Cry) proteins derived from Bacillus thuringiensis. Cry34Ab1 and Cry35Ab1 together comprise a binary insecticidal toxin with specific activity against WCR. These proteins have been developed as insect resistance traits in commercialized corn hybrids resistant to WCR feeding damage. Cry34/35Ab1 is a pore forming toxin, but the specific effects of Cry34/35Ab1 on WCR cells and tissues have not been well characterized microscopically, and the overall histopathology is poorly understood. Using high-resolution resin-based histopathology methods, the effects of Cry34/35Ab1 as well as Cry3Aa1, Cry6Aa1, and the Photorhabdus toxin complex protein TcdA have been directly visualized and documented. Clear symptoms of intoxication were observed for all insecticidal proteins tested, including swelling and sloughing of enterocytes, constriction of midgut circular muscles, stem cell activation, and obstruction of the midgut lumen. These data demonstrate the effects of these insecticidal proteins on WCR midgut cells, and the collective response of the midgut to intoxication. Taken together, these results advance our understanding of the insect cell biology and pathology of these insecticidal proteins, which should further the field of insect resistance traits and corn rootworm management. Full article
(This article belongs to the Special Issue The Insecticidal Bacterial Toxins in Modern Agriculture)
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Open AccessFeature PaperArticle Third Generation Antivenomics: Pushing the Limits of the In Vitro Preclinical Assessment of Antivenoms
Toxins 2017, 9(5), 158; doi:10.3390/toxins9050158
Received: 20 April 2017 / Revised: 5 May 2017 / Accepted: 5 May 2017 / Published: 10 May 2017
Cited by 1 | PDF Full-text (2352 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Second generation antivenomics is a translational venomics approach designed to complement in vivo preclinical neutralization assays. It provides qualitative and quantitative information on the set of homologous and heterologous venom proteins presenting antivenom-recognized epitopes and those exhibiting impaired immunoreactivity. In a situation of
[...] Read more.
Second generation antivenomics is a translational venomics approach designed to complement in vivo preclinical neutralization assays. It provides qualitative and quantitative information on the set of homologous and heterologous venom proteins presenting antivenom-recognized epitopes and those exhibiting impaired immunoreactivity. In a situation of worrying antivenom shortage in many tropical and sub-tropical regions with high snakebite mortality and morbidity rates, such knowledge has the potential to facilitate the optimal deployment of currently existing antivenoms and to aid in the rational design of novel broad specificity antidotes. The aim of the present work was to expand the analytical capability of the immunoaffinity second-generation antivenomics platform, endowing it with the ability to determine the maximal binding capacity of an antivenom toward the different toxins present in a venom, and to quantify the fraction of venom-specific antibodies present in a given antivenom. The application of this new platform, termed third generation (3G) antivenomics, in the preclinical evaluation of antivenoms is illustrated in this paper for the case of antivenom EchiTAb-Plus-ICP® reactivity towards the toxins of homologous (B. arietans) and heterologous (N. melanoleuca) venoms. Full article
(This article belongs to the Special Issue Use of Antibodies/Antivenom Against Envenoming)
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Open AccessArticle Assessment of Inheritance and Fitness Costs Associated with Field-Evolved Resistance to Cry3Bb1 Maize by Western Corn Rootworm
Toxins 2017, 9(5), 159; doi:10.3390/toxins9050159
Received: 31 March 2017 / Revised: 4 May 2017 / Accepted: 5 May 2017 / Published: 11 May 2017
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Abstract
The western corn rootworm, Diabrotica virgifera virgifera LeConte, is among the most serious insect pests of maize in North America. One strategy used to manage this pest is transgenic maize that produces one or more crystalline (Cry) toxins derived from the bacterium Bacillus
[...] Read more.
The western corn rootworm, Diabrotica virgifera virgifera LeConte, is among the most serious insect pests of maize in North America. One strategy used to manage this pest is transgenic maize that produces one or more crystalline (Cry) toxins derived from the bacterium Bacillus thuringiensis (Bt). To delay Bt resistance by insect pests, refuges of non-Bt maize are grown in conjunction with Bt maize. Two factors influencing the success of the refuge strategy to delay resistance are the inheritance of resistance and fitness costs, with greater delays in resistance expected when inheritance of resistance is recessive and fitness costs are present. We measured inheritance and fitness costs of resistance for two strains of western corn rootworm with field-evolved resistance to Cry3Bb1 maize. Plant-based and diet-based bioassays revealed that the inheritance of resistance was non-recessive. In a greenhouse experiment, in which larvae were reared on whole maize plants in field soil, no fitness costs of resistance were detected. In a laboratory experiment, in which larvae experienced intraspecific and interspecific competition for food, a fitness cost of delayed larval development was identified, however, no other fitness costs were found. These findings of non-recessive inheritance of resistance and minimal fitness costs, highlight the potential for the rapid evolution of resistance to Cry3Bb1 maize by western corn rootworm, and may help to improve resistance management strategies for this pest. Full article
(This article belongs to the Special Issue The Insecticidal Bacterial Toxins in Modern Agriculture)
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Open AccessArticle Molecular Epidemiology of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Ovine Dairy Chain and in Farm-Related Humans
Toxins 2017, 9(5), 161; doi:10.3390/toxins9050161
Received: 17 March 2017 / Revised: 5 May 2017 / Accepted: 9 May 2017 / Published: 16 May 2017
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Abstract
Staphylococcus aureus is a major cause of clinical infections in humans and its enterotoxins cause foodborne disease. In the present study, we tested a total of 51 isolates of S. aureus from small-ruminant dairy farms with artisan dairy facilities, all located in Latium,
[...] Read more.
Staphylococcus aureus is a major cause of clinical infections in humans and its enterotoxins cause foodborne disease. In the present study, we tested a total of 51 isolates of S. aureus from small-ruminant dairy farms with artisan dairy facilities, all located in Latium, Italy. The farms have a known history of a high prevalence of methicillin-resistant S. aureus (MRSA). Most of the MRSA isolates (27 of 51) belonged to spa-type t127 (43.1%), followed by t2678 (3.9%), t044 (2%), t1166 (2%), and t1773 (2%). PFGE performed on mecA positive strains identified one cluster (≥ 80% of similarity), comprising 22 MRSA. Nine of twenty-two MRSA isolates were assigned human host origin, and 13 isolates did not belong to a specific host. During the characterization study, one strain isolated from bulk tank milk samples harbored the pvl gene; the strain was not enterotoxigenic with a non-specific host according to the biotyping scheme, highlighting the possible emerging risk of transmission of bacterial virulence factors by foods, the environment, and foodhandlers. These findings stress the importance of hygienic measures at all processing steps of the food production chain and underline that monitoring for the presence of MRSA throughout the food chain is essential for public health. Full article
(This article belongs to the collection Staphylococcus aureus Toxins)
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Open AccessArticle HDAC8 Prevents Anthrax Lethal Toxin-induced Cell Cycle Arrest through Silencing PTEN in Human Monocytic THP-1 Cells
Toxins 2017, 9(5), 162; doi:10.3390/toxins9050162
Received: 19 April 2017 / Revised: 9 May 2017 / Accepted: 10 May 2017 / Published: 16 May 2017
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Abstract
Anthrax lethal toxin (LeTx) is a cytotoxic virulence factor that causes cell cycle arrest and cell death in various cell types. However, susceptibility to the cytotoxic effects varies depending on cell types. In proliferating monocytes, LeTx has only transient cytotoxic effects due to
[...] Read more.
Anthrax lethal toxin (LeTx) is a cytotoxic virulence factor that causes cell cycle arrest and cell death in various cell types. However, susceptibility to the cytotoxic effects varies depending on cell types. In proliferating monocytes, LeTx has only transient cytotoxic effects due to activation of the phosphoinositide 3-kinase (PI3K)-AKT-mediated adaptive responses. To date, the mechanism of LeTx in activating PI3K-AKT signaling axis is unknown. This study shows that the histone deacetylase 8 (HDAC8) is involved in activating PI3K-AKT signaling axis through down-regulating the phosphatase and tensin homolog 1 (PTEN) in human monocytic THP-1 cells. The HDAC8-specific activator TM-2-51 and inhibitor PCI-34051 enhanced and prevented, respectively, AKT activation and cell cycle progression in LeTx-treated cells. Furthermore, HDAC8 induced tri-methylation of histone H3 lysine 27 (H3K27me3), which is known to suppress PTEN expression, through at least in part down-regulating the H3K27me3 eraser Jumonji Domain Containing (JMJD) 3. Importantly, the JMJD3-specific inhibitor GSK-J4 induced AKT activation and protected cell cycle arrest in LeTx-treated cells, regardless the presence of HDAC8 activity. Collectively, this study for the first time demonstrated that HDAC8 activity determines susceptibility to cell cycle arrest induced by LeTx, through regulating the PI3K-PTEN-AKT signaling axis. Full article
(This article belongs to the collection Anthrax Toxins)
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Open AccessArticle Evaluation of Ochratoxin Recognition by Peptides Using Explicit Solvent Molecular Dynamics
Toxins 2017, 9(5), 164; doi:10.3390/toxins9050164
Received: 31 January 2017 / Revised: 9 April 2017 / Accepted: 9 May 2017 / Published: 13 May 2017
Cited by 1 | PDF Full-text (1171 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Biosensing platforms based on peptide recognition provide a cost-effective and stable alternative to antibody-based capture and discrimination of ochratoxin-A (OTA) vs. ochratoxin-B (OTB) in monitoring bioassays. Attempts to engineer peptides with improved recognition efficacy require thorough structural and thermodynamic characterization of the binding-competent
[...] Read more.
Biosensing platforms based on peptide recognition provide a cost-effective and stable alternative to antibody-based capture and discrimination of ochratoxin-A (OTA) vs. ochratoxin-B (OTB) in monitoring bioassays. Attempts to engineer peptides with improved recognition efficacy require thorough structural and thermodynamic characterization of the binding-competent conformations. Classical molecular dynamics (MD) approaches alone do not provide a thorough assessment of a peptide’s recognition efficacy. In this study, in-solution binding properties of four different peptides, a hexamer (SNLHPK), an octamer (CSIVEDGK), NFO4 (VYMNRKYYKCCK), and a 13-mer (GPAGIDGPAGIRC), which were previously generated for OTA-specific recognition, were evaluated using an advanced MD simulation approach involving accelerated configurational search and predictive modeling. Peptide configurations relevant to ochratoxin binding were initially generated using biased exchange metadynamics and the dynamic properties associated with the in-solution peptide–ochratoxin binding were derived from Markov State Models. Among the various peptides, NFO4 shows superior in-solution OTA sensing and also shows superior selectivity for OTA vs. OTB due to the lower penalty associated with solvating its bound complex. Advanced MD approaches provide structural and energetic insights critical to the hapten-specific recognition to aid the engineering of peptides with better sensing efficacies. Full article
(This article belongs to the collection Biorecognition Assays for Mycotoxins)
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Open AccessArticle The Vip3Ag4 Insecticidal Protoxin from Bacillus thuringiensis Adopts A Tetrameric Configuration That Is Maintained on Proteolysis
Toxins 2017, 9(5), 165; doi:10.3390/toxins9050165
Received: 17 January 2017 / Revised: 11 May 2017 / Accepted: 12 May 2017 / Published: 14 May 2017
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Abstract
The Vip3 proteins produced during vegetative growth by strains of the bacterium Bacillus thuringiensis show insecticidal activity against lepidopteran insects with a mechanism of action that may involve pore formation and apoptosis. These proteins are promising supplements to our arsenal of insecticidal proteins,
[...] Read more.
The Vip3 proteins produced during vegetative growth by strains of the bacterium Bacillus thuringiensis show insecticidal activity against lepidopteran insects with a mechanism of action that may involve pore formation and apoptosis. These proteins are promising supplements to our arsenal of insecticidal proteins, but the molecular details of their activity are not understood. As a first step in the structural characterisation of these proteins, we have analysed their secondary structure and resolved the surface topology of a tetrameric complex of the Vip3Ag4 protein by transmission electron microscopy. Sites sensitive to proteolysis by trypsin are identified and the trypsin-cleaved protein appears to retain a similar structure as an octomeric complex comprising four copies each of the ~65 kDa and ~21 kDa products of proteolysis. This processed form of the toxin may represent the active toxin. The quality and monodispersity of the protein produced in this study make Vip3Ag4 a candidate for more detailed structural analysis using cryo-electron microscopy. Full article
(This article belongs to the Special Issue Cellular Entry of Binary and Pore-Forming Bacterial Toxins)
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Open AccessArticle iTRAQ Mitoproteome Analysis Reveals Mechanisms of Programmed Cell Death in Arabidopsis thaliana Induced by Ochratoxin A
Toxins 2017, 9(5), 167; doi:10.3390/toxins9050167
Received: 5 April 2017 / Revised: 9 May 2017 / Accepted: 15 May 2017 / Published: 18 May 2017
PDF Full-text (1996 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ochratoxin A (OTA) is one of the most common and dangerous mycotoxins in the world. Previous work indicated that OTA could elicit spontaneous HR-like lesions formation Arabidopsis thaliana, reactive oxygen species (ROS) play an important role in OTA toxicity, and their major
[...] Read more.
Ochratoxin A (OTA) is one of the most common and dangerous mycotoxins in the world. Previous work indicated that OTA could elicit spontaneous HR-like lesions formation Arabidopsis thaliana, reactive oxygen species (ROS) play an important role in OTA toxicity, and their major endogenous source is mitochondria. However, there has been no evidence as to whether OTA induces directly PCD in plants until now. In this study, the presence of OTA in Arabidopsis thaliana leaves triggered accelerated respiration, increased production of mitochondrial ROS, the opening of ROS-dependent mitochondrial permeability transition pores and a decrease in mitochondrial membrane potential as well as the release of cytochrome c into the cytosol. There were 42 and 43 significantly differentially expressed proteins identified in response to exposure to OTA for 8 and 24 h, respectively, according to iTRAQ analysis. These proteins were mainly involved in perturbation of the mitochondrial electron transport chain, interfering with ATP synthesis and inducing PCD. Digital gene expression data at transcriptional level was consistent with the cell death induced by OTA being PCD. These results indicated that mitochondrial dysfunction was a prerequisite for OTA-induced PCD and the initiation and execution of PCD via a mitochondrial-mediated pathway. Full article
(This article belongs to the collection Ochratoxins-Collection)
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Open AccessArticle Transcriptional and Physiological Responses to Nutrient Loading on Toxin Formation and Photosynthesis in Microcystis Aeruginosa FACHB-905
Toxins 2017, 9(5), 168; doi:10.3390/toxins9050168
Received: 6 April 2017 / Revised: 8 May 2017 / Accepted: 11 May 2017 / Published: 17 May 2017
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Abstract
An important goal of understanding harmful algae blooms is to determine how environmental factors affect the growth and toxin formation of toxin-producing species. In this study, we investigated the transcriptional responses of toxin formation gene (mcyB) and key photosynthesis genes (
[...] Read more.
An important goal of understanding harmful algae blooms is to determine how environmental factors affect the growth and toxin formation of toxin-producing species. In this study, we investigated the transcriptional responses of toxin formation gene (mcyB) and key photosynthesis genes (psaB, psbD and rbcL) of Microcystis aeruginosa FACHB-905 in different nutrient loading conditions using real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR). Three physio-biochemical parameters (malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH)) were also evaluated to provide insight into the physiological responses of Microcystis cells. We observed an upregulation of mcyB gene in nutrient-deficient conditions, especially in nitrogen (N) limitation condition, and the transcript abundance declined after the nutrient were resupplied. Differently, high transcription levels were seen in phosphorus (P) deficient treatments for key photosynthesis genes throughout the culture period, while those in N-deficient cells varied with time, suggesting an adaptive regulation of Microsystis cells to nutrient stress. Increased contents of antioxidant enzymes (SOD and GSH) were seen in both N and P-deficient conditions, suggesting the presence of excess amount of free radical generation caused by nutrient stress. The amount of SOD and GSH continued to increase even after the nutrient was reintroduced and a strong correlation was seen between the MDA and enzyme activities, indicating the robust effort of rebalancing the redox system in Microcystis cells. Based on these transcriptional and physiological responses of M. aeruginosa to nutrient loading, these results could provide more insight into Microcystis blooms management and toxin formation regulation. Full article
(This article belongs to the collection Marine and Freshwater Toxins)
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Open AccessFeature PaperArticle Development of a LC-MS/MS Method for the Multi-Mycotoxin Determination in Composite Cereal-Based Samples
Toxins 2017, 9(5), 169; doi:10.3390/toxins9050169
Received: 7 April 2017 / Revised: 8 May 2017 / Accepted: 10 May 2017 / Published: 18 May 2017
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Abstract
The analytical scenario for determining contaminants in the food and feed sector is constantly prompted by the progress and improvement of knowledge and expertise of researchers and by the technical innovation of the instrumentation available. Mycotoxins are agricultural contaminants of fungal origin occurring
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The analytical scenario for determining contaminants in the food and feed sector is constantly prompted by the progress and improvement of knowledge and expertise of researchers and by the technical innovation of the instrumentation available. Mycotoxins are agricultural contaminants of fungal origin occurring at all latitudes worldwide and being characterized by acute and chronic effects on human health and animal wellness, depending on the species sensitivity. The major mycotoxins of food concern are aflatoxin B1 and ochratoxin A, the first for its toxicity, and the second for its recurrent occurrence. However, the European legislation sets maximum limits for mycotoxins, such as aflatoxin B1, ochratoxin A, deoxynivalenol, fumonisins, and zearalenone, and indicative limits for T-2 and HT-2 toxins. Due to the actual probability that co-occurring mycotoxins are present in a food or feed product, nowadays, the availability of reliable, sensitive, and versatile multi-mycotoxin methods is assuming a relevant importance. Due to the wide range of matrices susceptible to mycotoxin contamination and the possible co-occurrence, a multi-mycotoxin and multi-matrix method was validated in liquid chromatography-tandem mass spectrometry (LC-MS/MS) with the purpose to overcome specific matrix effects and analyze complex cereal-based samples within the Italian Total Diet Study project. Full article
(This article belongs to the Special Issue LC-MS/MS Method for Mycotoxin Analysis)
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Open AccessArticle Coagulating Colubrids: Evolutionary, Pathophysiological and Biodiscovery Implications of Venom Variations between Boomslang (Dispholidus typus) and Twig Snake (Thelotornis mossambicanus)
Toxins 2017, 9(5), 171; doi:10.3390/toxins9050171
Received: 16 January 2017 / Revised: 15 May 2017 / Accepted: 15 May 2017 / Published: 19 May 2017
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Abstract
Venoms can deleteriously affect any physiological system reachable by the bloodstream, including directly interfering with the coagulation cascade. Such coagulopathic toxins may be anticoagulants or procoagulants. Snake venoms are unique in their use of procoagulant toxins for predatory purposes. The boomslang (Dispholidus
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Venoms can deleteriously affect any physiological system reachable by the bloodstream, including directly interfering with the coagulation cascade. Such coagulopathic toxins may be anticoagulants or procoagulants. Snake venoms are unique in their use of procoagulant toxins for predatory purposes. The boomslang (Dispholidus typus) and the twig snakes (Thelotornis species) are iconic African snakes belonging to the family Colubridae. Both species produce strikingly similar lethal procoagulant pathologies. Despite these similarities, antivenom is only produced for treating bites by D. typus, and the mechanisms of action of both venoms have been understudied. In this study, we investigated the venom of D. typus and T. mossambicanus utilising a range of proteomic and bioactivity approaches, including determining the procoagulant properties of both venoms in relation to the human coagulation pathways. In doing so, we developed a novel procoagulant assay, utilising a Stago STA-R Max analyser, to accurately detect real time clotting in plasma at varying concentrations of venom. This approach was used to assess the clotting capabilities of the two venoms both with and without calcium and phospholipid co-factors. We found that T. mossambicanus produced a significantly stronger coagulation response compared to D. typus. Functional enzyme assays showed that T. mossambicanus also exhibited a higher metalloprotease and phospholipase activity but had a much lower serine protease activity relative to D. typus venom. The neutralising capability of the available boomslang antivenom was also investigated on both species, with it being 11.3 times more effective upon D. typus venom than T. mossambicanus. In addition to being a faster clotting venom, T. mossambicanus was revealed to be a much more complex venom composition than D. typus. This is consistent with patterns seen for other snakes with venom complexity linked to dietary complexity. Consistent with the external morphological differences in head shape between the two species, CT and MRI analyses revealed significant internal structural differences in skull architecture and venom gland anatomy. This study increases our understanding of not only the biodiscovery potential of these medically important species but also increases our knowledge of the pathological relationship between venom and the human coagulation cascade. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessArticle Doses of Immunogen Contribute to Specificity Spectrums of Antibodies against Aflatoxin
Toxins 2017, 9(5), 172; doi:10.3390/toxins9050172
Received: 28 February 2017 / Revised: 3 May 2017 / Accepted: 17 May 2017 / Published: 19 May 2017
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Abstract
Research about antibody specificity spectra was conducted to develop single-specific antibodies or broad-specific antibodies. Aflatoxins, as one class of high-toxicity mycotoxins, were selected as the research targets to investigate the effect of the immunogen dose on antibody specificity spectra. For this aim, 16
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Research about antibody specificity spectra was conducted to develop single-specific antibodies or broad-specific antibodies. Aflatoxins, as one class of high-toxicity mycotoxins, were selected as the research targets to investigate the effect of the immunogen dose on antibody specificity spectra. For this aim, 16 monoclonal antibodies were induced by low or high doses of aflatoxin B1-BSA, and 34 monoclonal antibodies were induced by low or high doses of aflatoxin M1-BSA. The specificities of the antibodies induced, whether by aflatoxin B1 conjugate or aflatoxin M1 conjugate, indicated that the low dose of the immunogen induced a narrow spectrum of antibody specificity, while the high dose of the immunogen showed an advantage to form a broad spectrum of antibody specificity. Therefore, this report provides important information for the development of new antibodies against small molecules like aflatoxins. Full article
(This article belongs to the collection Aflatoxins)
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Open AccessArticle RBC Adherence of Immune Complexes Containing Botulinum Toxin Improves Neutralization and Macrophage Uptake
Toxins 2017, 9(5), 173; doi:10.3390/toxins9050173
Received: 5 April 2017 / Revised: 12 May 2017 / Accepted: 15 May 2017 / Published: 19 May 2017
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Abstract
In the paralytic disease botulism, the botulinum neurotoxin (BoNT) passes through the bloodstream to reach and inactivate neuromuscular junctions. Monoclonal antibodies (mAbs) may be useful BoNT countermeasures, as mAb combinations can rapidly clear BoNT from the blood circulation. We have previously shown that
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In the paralytic disease botulism, the botulinum neurotoxin (BoNT) passes through the bloodstream to reach and inactivate neuromuscular junctions. Monoclonal antibodies (mAbs) may be useful BoNT countermeasures, as mAb combinations can rapidly clear BoNT from the blood circulation. We have previously shown that the BoNT-neutralizing potency of mAbs can be improved through red blood cell (RBC) immunoadherence. For example, a fusion protein (FP) that adheres biotinylated mAbs to the RBC surface enabled a pair of mAbs to neutralize 5000 LD50 BoNT/A in the mouse protection assay. Here, we added two mAbs to that combination, creating a 4-mAb:FP complex that neutralized 40,000 LD50 BoNT/A in vivo, and analyzed functional correlates of neutralization. The FP enhanced potency of BoNT/A immune complexes, providing the greatest magnitude of benefit to the 4-mAb combination. RBC binding of a BoNT/A complexed with 4-mAb:FP exhibited a bi-phasic clearance process in vivo. Most of the complexes were cleared within five minutes; the rest were cleared gradually over many hours. Peritoneal macrophages showed better uptake of the 4-mAb complex than the 3-mAb complex, and this was not affected by the presence of the FP. However, the addition of RBCs to the 4-mAb:FP BoNT/A doubled macrophage uptake of the complexes. Lastly, the 4-mAb:FP BoNT/A complex synergistically induced M2 macrophage polarization, as indicated by IL-10 expression, whether or not RBCs were present. RBC-targeted immunoadherence through the FP is a potent enhancer of mAb-mediated BoNT/A neutralization in vivo, and can have positive effects on BoNT/A sequestration, immune complex uptake, and macrophage activation. Full article
(This article belongs to the Special Issue Botulinum Neurotoxins Antibody and Vaccine)
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Open AccessArticle Screening of a Combinatorial Library of Organic Polymers for the Solid-Phase Extraction of Patulin from Apple Juice
Toxins 2017, 9(5), 174; doi:10.3390/toxins9050174
Received: 19 April 2017 / Revised: 14 May 2017 / Accepted: 17 May 2017 / Published: 20 May 2017
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Abstract
Patulin is a water-soluble mycotoxin produced by several species of fungi. Governmental bodies have placed it under scrutiny for its potential negative health effects, and maximum residue limits are fixed in specific food matrices to protect consumers’ health. Confirmatory analysis of patulin in
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Patulin is a water-soluble mycotoxin produced by several species of fungi. Governmental bodies have placed it under scrutiny for its potential negative health effects, and maximum residue limits are fixed in specific food matrices to protect consumers’ health. Confirmatory analysis of patulin in complex food matrices can be a difficult task, and sample clean-up treatments are frequently necessary before instrumental analyses. With the aim of simplifying the clean-up step, we prepared a 256-member combinatorial polymeric library based on 16 functional monomers, four cross-linkers and four different porogenic solvents. The library was screened for the binding towards patulin in different media (acetonitrile and citrate buffer at pH 3.2), with the goal of identifying polymer formulations with good binding properties towards the target compound. As a proof of concept, a methacrylic acid-co-pentaerithrytole tetraacrylate polymer prepared in chloroform was successfully used as a solid-phase extraction material for the clean-up and extraction of patulin from apple juice. Clean chromatographic patterns and acceptable recoveries were obtained for juice spiked with patulin at concentration levels of 25 (64 ± 12%), 50 (83 ± 5.6%) and 100 μg L−1 (76 ± 4.5%). The within-day and between-day reproducibility evaluated at a concentration level of 25 μg L−1 were 5.6 and 7.6%, respectively. Full article
(This article belongs to the Section Mycotoxins)
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Review

Jump to: Editorial, Research

Open AccessReview Mycotoxin Decontamination of Food: Cold Atmospheric Pressure Plasma versus “Classic” Decontamination
Toxins 2017, 9(5), 151; doi:10.3390/toxins9050151
Received: 15 March 2017 / Revised: 24 April 2017 / Accepted: 26 April 2017 / Published: 28 April 2017
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Abstract
Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing
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Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing to incorrect handling, transport and storage of the food, resulting in increased levels of mycotoxin contamination. Mycotoxins are structurally very diverse molecules necessitating versatile food decontamination approaches, which are grouped into physical, chemical and biological techniques. In this review, a new and promising approach involving the use of cold atmospheric pressure plasma is considered, which may overcome multiple weaknesses associated with the classical methods. In addition to its mycotoxin destruction efficiency, cold atmospheric pressure plasma is cost effective, ecologically neutral and has a negligible effect on the quality of food products following treatment in comparison to classical methods. Full article
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Open AccessReview Mitigation of Patulin in Fresh and Processed Foods and Beverages
Toxins 2017, 9(5), 157; doi:10.3390/toxins9050157
Received: 1 February 2017 / Revised: 13 April 2017 / Accepted: 3 May 2017 / Published: 11 May 2017
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Abstract
Patulin is a mycotoxin of food safety concern. It is produced by numerous species of fungi growing on fruits and vegetables. Exposure to the toxin is connected to issues neurological, immunological, and gastrointestinal in nature. Regulatory agencies worldwide have established maximum allowable levels
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Patulin is a mycotoxin of food safety concern. It is produced by numerous species of fungi growing on fruits and vegetables. Exposure to the toxin is connected to issues neurological, immunological, and gastrointestinal in nature. Regulatory agencies worldwide have established maximum allowable levels of 50 µg/kg in foods. Despite regulations, surveys continue to find patulin in commercial food and beverage products, in some cases, to exceed the maximum limits. Patulin content in food can be mitigated throughout the food processing chain. Proper handling, storage, and transportation of food can limit fungal growth and patulin production. Common processing techniques including pasteurisation, filtration, and fermentation all have an effect on patulin content in food but individually are not sufficient safety measures. Novel methods to remove or detoxify patulin have been reviewed. Non-thermal processing techniques such as high hydrostatic pressure, UV radiation, enzymatic degradation, binding to microorganisms, and chemical degradation all have potential but have not been optimised. Until further refinement of these methods, the hurdle approach to processing should be used where food safety is concerned. Future development should focus on determining the nature and safety of chemicals produced from the breakdown of patulin in treatment techniques. Full article
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Open AccessFeature PaperReview Preclinical Evaluation of the Efficacy of Antivenoms for Snakebite Envenoming: State-of-the-Art and Challenges Ahead
Toxins 2017, 9(5), 163; doi:10.3390/toxins9050163
Received: 22 March 2017 / Revised: 17 April 2017 / Accepted: 10 May 2017 / Published: 13 May 2017
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Abstract
Animal-derived antivenoms constitute the mainstay in the therapy of snakebite envenoming. The efficacy of antivenoms to neutralize toxicity of medically-relevant snake venoms has to be demonstrated through meticulous preclinical testing before their introduction into the clinical setting. The gold standard in the preclinical
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Animal-derived antivenoms constitute the mainstay in the therapy of snakebite envenoming. The efficacy of antivenoms to neutralize toxicity of medically-relevant snake venoms has to be demonstrated through meticulous preclinical testing before their introduction into the clinical setting. The gold standard in the preclinical assessment and quality control of antivenoms is the neutralization of venom-induced lethality. In addition, depending on the pathophysiological profile of snake venoms, the neutralization of other toxic activities has to be evaluated, such as hemorrhagic, myotoxic, edema-forming, dermonecrotic, in vitro coagulant, and defibrinogenating effects. There is a need to develop laboratory assays to evaluate neutralization of other relevant venom activities. The concept of the 3Rs (Replacement, Reduction, and Refinement) in Toxinology is of utmost importance, and some advances have been performed in their implementation. A significant leap forward in the study of the immunological reactivity of antivenoms against venoms has been the development of “antivenomics”, which brings the analytical power of mass spectrometry to the evaluation of antivenoms. International partnerships are required to assess the preclinical efficacy of antivenoms against snake venoms in different regions of the world in order to have a detailed knowledge on the neutralizing profile of these immunotherapeutics. Full article
(This article belongs to the Special Issue Use of Antibodies/Antivenom Against Envenoming)
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Open AccessReview Tetrodotoxin-Producing Bacteria: Detection, Distribution and Migration of the Toxin in Aquatic Systems
Toxins 2017, 9(5), 166; doi:10.3390/toxins9050166
Received: 3 April 2017 / Revised: 12 May 2017 / Accepted: 12 May 2017 / Published: 17 May 2017
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Abstract
This review is devoted to the marine bacterial producers of tetrodotoxin (TTX), a potent non-protein neuroparalytic toxin. In addition to the issues of the ecology and distribution of TTX-producing bacteria, this review examines issues relating to toxin migration from bacteria to TTX-bearing animals.
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This review is devoted to the marine bacterial producers of tetrodotoxin (TTX), a potent non-protein neuroparalytic toxin. In addition to the issues of the ecology and distribution of TTX-producing bacteria, this review examines issues relating to toxin migration from bacteria to TTX-bearing animals. It is shown that the mechanism of TTX extraction from toxin-producing bacteria to the environment occur through cell death, passive/active toxin excretion, or spore germination of spore-forming bacteria. Data on TTX microdistribution in toxic organs of TTX-bearing animals indicate toxin migration from the digestive system to target organs through the transport system of the organism. The role of symbiotic microflora in animal toxicity is also discussed: despite low toxin production by bacterial strains in laboratory conditions, even minimal amounts of TTX produced by intestinal microflora of an animal can contribute to its toxicity. Special attention is paid to methods of TTX detection applicable to bacteria. Due to the complexity of toxin detection in TTX-producing bacteria, it is necessary to use several methods based on different methodological approaches. Issues crucial for further progress in detecting natural sources of TTX investigation are also considered. Full article
(This article belongs to the collection Marine and Freshwater Toxins)
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