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Open AccessEditor’s ChoiceArticle Degradation of Aflatoxins by Means of Laccases from Trametes versicolor: An In Silico Insight
Toxins 2017, 9(1), 17; doi:10.3390/toxins9010017
Received: 16 November 2016 / Revised: 16 December 2016 / Accepted: 26 December 2016 / Published: 1 January 2017
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Abstract
Mycotoxins are secondary metabolites of fungi that contaminate food and feed, and are involved in a series of foodborne illnesses and disorders in humans and animals. The mitigation of mycotoxin content via enzymatic degradation is a strategy to ensure safer food and feed,
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Mycotoxins are secondary metabolites of fungi that contaminate food and feed, and are involved in a series of foodborne illnesses and disorders in humans and animals. The mitigation of mycotoxin content via enzymatic degradation is a strategy to ensure safer food and feed, and to address the forthcoming issues in view of the global trade and sustainability. Nevertheless, the search for active enzymes is still challenging and time-consuming. The in silico analysis may strongly support the research by providing the evidence-based hierarchization of enzymes for a rational design of more effective experimental trials. The present work dealt with the degradation of aflatoxin B1 and M1 by laccase enzymes from Trametes versicolor. The enzymes–substrate interaction for various enzyme isoforms was investigated through 3D molecular modeling techniques. Structural differences among the isoforms have been pinpointed, which may cause different patterns of interaction between aflatoxin B1 and M1. The possible formation of different products of degradation can be argued accordingly. Moreover, the laccase gamma isoform was identified as the most suitable for protein engineering aimed at ameliorating the substrate specificity. Overall, 3D modeling proved to be an effective analytical tool to assess the enzyme–substrate interaction and provided a solid foothold for supporting the search of degrading enzyme at the early stage. Full article
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Open AccessEditor’s ChoiceArticle Bioactivity of Natural and Engineered Antimicrobial Peptides from Venom of the Scorpions Urodacus yaschenkoi and U. manicatus
Toxins 2017, 9(1), 22; doi:10.3390/toxins9010022
Received: 26 November 2016 / Revised: 26 December 2016 / Accepted: 29 December 2016 / Published: 6 January 2017
Cited by 3 | PDF Full-text (1593 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The spread of multidrug-resistant human pathogens has drawn attention towards antimicrobial peptides (AMPs), which are major players in the innate immune systems of many organisms, including vertebrates, invertebrates, plants and microbes. Scorpion venom is an abundant source of novel and potent AMPs. Here,
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The spread of multidrug-resistant human pathogens has drawn attention towards antimicrobial peptides (AMPs), which are major players in the innate immune systems of many organisms, including vertebrates, invertebrates, plants and microbes. Scorpion venom is an abundant source of novel and potent AMPs. Here, we investigated natural and engineered AMPs from the scorpions Urodacus yaschenkoi and U. manicatus to determine their antimicrobial spectra as well as their hemolytic/cytotoxic activity. None of the AMPs were active against fungi, but many of them were active at low concentrations (0.25–30 µM) against seven different bacteria. Hemolytic and cytotoxic activities were determined using pig erythrocytes and baby hamster kidney cells, respectively. The amino acid substitutions in the engineered AMPs did not inhibit cytotoxicity, but reduced hemolysis and therefore increased the therapeutic indices. The phylogenetic analysis of scorpion AMPs revealed they are closely related and the GXK motif is highly conserved. The engineered scorpion AMPs offer a promising alternative for the treatment of multidrug-resistant bacterial infections and could be modified further to reduce their hemolytic/cytotoxic activity. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessEditor’s ChoiceArticle Novel Aflatoxin-Degrading Enzyme from Bacillus shackletonii L7
Toxins 2017, 9(1), 36; doi:10.3390/toxins9010036
Received: 22 September 2016 / Revised: 10 January 2017 / Accepted: 11 January 2017 / Published: 14 January 2017
Cited by 1 | PDF Full-text (3161 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Food and feed contamination by aflatoxin (AF)B1 has adverse economic and health consequences. AFB1 degradation by microorganisms or microbial enzymes provides a promising preventive measure. To this end, the present study tested 43 bacterial isolates collected from maize, rice, and soil
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Food and feed contamination by aflatoxin (AF)B1 has adverse economic and health consequences. AFB1 degradation by microorganisms or microbial enzymes provides a promising preventive measure. To this end, the present study tested 43 bacterial isolates collected from maize, rice, and soil samples for AFB1-reducing activity. The higher activity was detected in isolate L7, which was identified as Bacillus shackletonii. L7 reduced AFB1, AFB2, and AFM1 levels by 92.1%, 84.1%, and 90.4%, respectively, after 72 h at 37 °C. The L7 culture supernatant degraded more AFB1 than viable cells and cell extracts; and the degradation activity was reduced from 77.9% to 15.3% in the presence of proteinase K and sodium dodecyl sulphate. A thermostable enzyme purified from the boiled supernatant was designated as Bacillus aflatoxin-degrading enzyme (BADE). An overall 9.55-fold purification of BADE with a recovery of 39.92% and an activity of 3.85 × 103 U·mg−1 was obtained using chromatography on DEAE-Sepharose. BADE had an estimated molecular mass of 22 kDa and exhibited the highest activity at 70 °C and pH 8.0, which was enhanced by Cu2+ and inhibited by Zn2+, Mn2+, Mg2+, and Li+. BADE is the major protein involved in AFB1 detoxification. This is the first report of a BADE isolated from B. shackletonii, which has potential applications in the detoxification of aflatoxins during food and feed processing. Full article
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Open AccessEditor’s ChoiceArticle Metabolism of Zearalenone and Its Major Modified Forms in Pigs
Toxins 2017, 9(2), 56; doi:10.3390/toxins9020056
Received: 15 January 2017 / Revised: 2 February 2017 / Accepted: 6 February 2017 / Published: 8 February 2017
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Abstract
The Fusarium mycotoxin zearalenone (ZEN) can be conjugated with polar molecules, like sugars or sulfates, by plants and fungi. To date, the fate of these modified forms of ZEN has not yet been elucidated in animals. In order to investigate whether ZEN conjugates
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The Fusarium mycotoxin zearalenone (ZEN) can be conjugated with polar molecules, like sugars or sulfates, by plants and fungi. To date, the fate of these modified forms of ZEN has not yet been elucidated in animals. In order to investigate whether ZEN conjugates contribute to the total ZEN exposure of an individual, ZEN (10 µg/kg b.w.) and equimolar amounts of two of its plant metabolites (ZEN-14-O-β-glucoside, ZEN-16-O-β-glucoside) and of one fungal metabolite (ZEN-14-sulfate) were orally administered to four pigs as a single bolus using a repeated measures design. The concentrations of ZEN, its modified forms and its mammalian metabolites ZEN-14-glucuronide, α-zearalenol (α-ZEL) and α-ZEL-14-glucuronide in excreta were analyzed by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) based methods. The biological recovery of ZEN in urine was 26% ± 10%, the total biological recovery in excreta was 40% ± 8%. Intact ZEN-14-sulfate, ZEN-14-O-β-glucoside and ZEN-16-O-β-glucoside were neither detected in urine nor in feces. After ZEN-14-sulfate application, 19% ± 5% of the administered dose was recovered in urine. In feces, no ZEN metabolites were detected. The total biological recoveries of ZEN-14-O-β-glucoside and ZEN-16-O-β-glucoside in the form of their metabolites in urine were 19% ± 11% and 13% ± 7%, respectively. The total biological recoveries in urine and feces amounted to 48% ± 7% and 34 ± 3%. An explanation for the low biological recoveries could be extensive metabolization by intestinal bacteria to yet unknown metabolites. In summary, ZEN-14-sulfate, ZEN-14-O-β-glucoside, and ZEN-16-O-β-glucoside were completely hydrolyzed in the gastrointestinal tract of swine, thus contributing to the overall toxicity of ZEN. Full article
(This article belongs to the collection Fusarium Toxins – Relevance for Human and Animal Health)
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Open AccessEditor’s ChoiceArticle Patulin Degradation by the Biocontrol Yeast Sporobolomyces sp. Is an Inducible Process
Toxins 2017, 9(2), 61; doi:10.3390/toxins9020061
Received: 12 January 2017 / Revised: 2 February 2017 / Accepted: 7 February 2017 / Published: 10 February 2017
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Abstract
Patulin is a mycotoxin produced by Penicillium expansum and a common contaminant of pome fruits and their derived products worldwide. It is considered to be mutagenic, genotoxic, immunotoxic, teratogenic and cytotoxic, and the development of strategies to reduce this contamination is an active
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Patulin is a mycotoxin produced by Penicillium expansum and a common contaminant of pome fruits and their derived products worldwide. It is considered to be mutagenic, genotoxic, immunotoxic, teratogenic and cytotoxic, and the development of strategies to reduce this contamination is an active field of research. We previously reported that Sporobolomyces sp. is able to degrade patulin and convert it into the breakdown products desoxypatulinic acid and ascladiol, both of which were found to be less toxic than patulin. The specific aim of this study was the evaluation of the triggering of the mechanisms involved in patulin resistance and degradation by Sporobolomyces sp. Cells pre-incubated in the presence of a low patulin concentration showed a higher resistance to patulin toxicity and a faster kinetics of degradation. Similarly, patulin degradation was faster when crude intracellular protein extracts of Sporobolomyces sp. were prepared from cells pre-treated with the mycotoxin, indicating the induction of the mechanisms involved in the resistance and degradation of the mycotoxin by Sporobolomyces sp. This study contributes to the understanding of the mechanisms of patulin resistance and degradation by Sporobolomyces sp., which is an essential prerequisite for developing an industrial approach aiming at the production of patulin-free products. Full article
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Open AccessEditor’s ChoiceArticle The Cardiovascular and Neurotoxic Effects of the Venoms of Six Bony and Cartilaginous Fish Species
Toxins 2017, 9(2), 67; doi:10.3390/toxins9020067
Received: 15 September 2016 / Accepted: 3 February 2017 / Published: 16 February 2017
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Abstract
Fish venoms are often poorly studied, in part due to the difficulty in obtaining, extracting, and storing them. In this study, we characterize the cardiovascular and neurotoxic effects of the venoms from the following six species of fish: the cartilaginous stingrays Neotrygon kuhlii
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Fish venoms are often poorly studied, in part due to the difficulty in obtaining, extracting, and storing them. In this study, we characterize the cardiovascular and neurotoxic effects of the venoms from the following six species of fish: the cartilaginous stingrays Neotrygon kuhlii and Himantura toshi, and the bony fish Platycephalus fucus, Girella tricuspidata, Mugil cephalus, and Dentex tumifrons. All venoms (10–100 μg/kg, i.v.), except G. tricuspidata and P. fuscus, induced a biphasic response on mean arterial pressure (MAP) in the anesthetised rat. P. fucus venom exhibited a hypotensive response, while venom from G. tricuspidata displayed a single depressor response. All venoms induced cardiovascular collapse at 200 μg/kg, i.v. The in vitro neurotoxic effects of venom were examined using the chick biventer cervicis nerve‐muscle (CBCNM) preparation. N. kuhlii, H. toshi, and P. fucus venoms caused concentration‐dependent inhibition of indirect twitches in the CBCNM preparation. These three venoms also inhibited responses to exogenous acetylcholine (ACh) and carbachol (CCh), but not potassium chloride (KCl), indicating a post‐synaptic mode of action. Venom from G. tricuspidata, M. cephalus, and D. tumifrons had no significant effect on indirect twitches or agonist responses in the CBCNM. Our results demonstrate that envenoming by these species of fish may result in moderate cardiovascular and/or neurotoxic effects. Future studies aimed at identifying the molecules responsible for these effects could uncover potentially novel lead compounds for future pharmaceuticals, in addition to generating new knowledge about the evolutionary relationships between venomous animals. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessEditor’s ChoiceCommunication Acute Oral Toxicity of Tetrodotoxin in Mice: Determination of Lethal Dose 50 (LD50) and No Observed Adverse Effect Level (NOAEL)
Toxins 2017, 9(3), 75; doi:10.3390/toxins9030075
Received: 9 January 2017 / Revised: 26 January 2017 / Accepted: 22 February 2017 / Published: 24 February 2017
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Abstract
Tetrodotoxin (TTX) is starting to appear in molluscs from the European waters and is a hazard to seafood consumers. This toxin blocks sodium channels resulting in neuromuscular paralysis and even death. As a part of the risk assessment process leading to a safe
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Tetrodotoxin (TTX) is starting to appear in molluscs from the European waters and is a hazard to seafood consumers. This toxin blocks sodium channels resulting in neuromuscular paralysis and even death. As a part of the risk assessment process leading to a safe seafood level for TTX, oral toxicity data are required. In this study, a 4-level Up and Down Procedure was designed in order to determine for the first time the oral lethal dose 50 (LD50) and the No Observed Adverse Effect Level (NOAEL) in mice by using an accurate well-characterized TTX standard. Full article
(This article belongs to the collection Marine and Freshwater Toxins)
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Open AccessEditor’s ChoiceArticle Detection of Cyanotoxins in Algae Dietary Supplements
Toxins 2017, 9(3), 76; doi:10.3390/toxins9030076
Received: 6 December 2016 / Revised: 17 February 2017 / Accepted: 21 February 2017 / Published: 25 February 2017
Cited by 2 | PDF Full-text (1583 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Algae dietary supplements are marketed worldwide as natural health products. Although their proprieties have been claimed as beneficial to improve overall health, there have been several previous reports of contamination by cyanotoxins. These products generally contain non-toxic cyanobacteria, but the methods of cultivation
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Algae dietary supplements are marketed worldwide as natural health products. Although their proprieties have been claimed as beneficial to improve overall health, there have been several previous reports of contamination by cyanotoxins. These products generally contain non-toxic cyanobacteria, but the methods of cultivation in natural waters without appropriate quality controls allow contamination by toxin producer species present in the natural environment. In this study, we investigated the presence of total microcystins, seven individual microcystins (RR, YR, LR, LA, LY, LW, LF), anatoxin-a, dihydroanatoxin-a, epoxyanatoxin-a, cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine in 18 different commercially available products containing Spirulina or Aphanizomenon flos-aquae. Total microcystins analysis was accomplished using a Lemieux oxidation and a chemical derivatization using dansyl chloride was needed for the simultaneous analysis of cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine. Moreover, the use of laser diode thermal desorption (LDTD) and ultra-high performance liquid chromatography (UHPLC) both coupled to high resolution mass spectrometry (HRMS) enabled high performance detection and quantitation. Out of the 18 products analyzed, 8 contained some cyanotoxins at levels exceeding the tolerable daily intake values. The presence of cyanotoxins in these algal dietary supplements reinforces the need for a better quality control as well as consumer’s awareness on the potential risks associated with the consumption of these supplements. Full article
(This article belongs to the Section Marine and Freshwater Toxins)
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Open AccessEditor’s ChoiceArticle Effects of Electron Beam Irradiation on Zearalenone and Ochratoxin A in Naturally Contaminated Corn and Corn Quality Parameters
Toxins 2017, 9(3), 84; doi:10.3390/toxins9030084
Received: 26 November 2016 / Accepted: 6 February 2017 / Published: 27 February 2017
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Abstract
Zearalenone (ZEN) and ochratoxin A (OTA) are secondary toxic metabolites widely present in grains and grain products. In this study, the effects of electron beam irradiation (EBI) on ZEN and OTA in corn and the quality of irradiated corn were investigated. Results indicated
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Zearalenone (ZEN) and ochratoxin A (OTA) are secondary toxic metabolites widely present in grains and grain products. In this study, the effects of electron beam irradiation (EBI) on ZEN and OTA in corn and the quality of irradiated corn were investigated. Results indicated that EBI significantly affected ZEN and OTA. The degradation rates of ZEN and OTA at 10 kGy in solution were 65.6% and 75.2%, respectively. The initial amounts significantly affected the degradation rate. ZEN and OTA in corn were decreased by the irradiation dose, and their degradation rates at 50 kGy were 71.1% and 67.9%, respectively. ZEN and OTA were more easily degraded in corn kernel than in corn flour. Moisture content (MC) played a vital role in ZEN and OTA degradation. High MC was attributed to high ZEN and OTA degradation. The quality of irradiated corn was evaluated on the basis of irradiation dose. L* value changed, but this change was not significant (p > 0.05). By contrast, a* and b* decreased significantly (p < 0.05) with irradiation dose. The fatty acid value increased significantly. The pasting properties, including peak, trough, breakdown, and final and setback viscosities, were also reduced significantly (p < 0.05) by irradiation. Our study verified that EBI could effectively degrade ZEN and OTA in corn. Irradiation could also affect corn quality. Full article
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Open AccessEditor’s ChoiceArticle Silver Nanoparticle-Based Fluorescence-Quenching Lateral Flow Immunoassay for Sensitive Detection of Ochratoxin A in Grape Juice and Wine
Toxins 2017, 9(3), 83; doi:10.3390/toxins9030083
Received: 24 November 2016 / Revised: 23 February 2017 / Accepted: 23 February 2017 / Published: 28 February 2017
Cited by 5 | PDF Full-text (2766 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A silver nanoparticle (AgNP)-based fluorescence-quenching lateral flow immunoassay with competitive format (cLFIA) was developed for sensitive detection of ochratoxin A (OTA) in grape juice and wine samples in the present study. The Ru(phen)32+-doped silica nanoparticles (RuNPs) were sprayed on
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A silver nanoparticle (AgNP)-based fluorescence-quenching lateral flow immunoassay with competitive format (cLFIA) was developed for sensitive detection of ochratoxin A (OTA) in grape juice and wine samples in the present study. The Ru(phen) 3 2 + -doped silica nanoparticles (RuNPs) were sprayed on the test and control line zones as background fluorescence signals. The AgNPs were designed as the fluorescence quenchers of RuNPs because they can block the exciting light transferring to the RuNP molecules. The proposed method exhibited high sensitivity for OTA detection, with a detection limit of 0.06 µg/L under optimized conditions. The method also exhibited a good linear range for OTA quantitative analysis from 0.08 µg/L to 5.0 µg/L. The reliability of the fluorescence-quenching cLFIA method was evaluated through analysis of the OTA-spiked red grape wine and juice samples. The average recoveries ranged from 88.0% to 110.0% in red grape wine and from 92.0% to 110.0% in grape juice. Meanwhile, less than a 10% coefficient variation indicated an acceptable precision of the cLFIA method. In summary, the new AgNP-based fluorescence-quenching cLFIA is a simple, rapid, sensitive, and accurate method for quantitative detection of OTA in grape juice and wine or other foodstuffs. Full article
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Open AccessEditor’s ChoiceArticle Crystal Structure of the Receptor-Binding Domain of Botulinum Neurotoxin Type HA, Also Known as Type FA or H
Toxins 2017, 9(3), 93; doi:10.3390/toxins9030093
Received: 25 January 2017 / Revised: 3 March 2017 / Accepted: 4 March 2017 / Published: 8 March 2017
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Abstract
Botulinum neurotoxins (BoNTs), which have been exploited as cosmetics and muscle-disorder treatment medicines for decades, are well known for their extreme neurotoxicity to humans. They pose a potential bioterrorism threat because they cause botulism, a flaccid muscular paralysis-associated disease that requires immediate antitoxin
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Botulinum neurotoxins (BoNTs), which have been exploited as cosmetics and muscle-disorder treatment medicines for decades, are well known for their extreme neurotoxicity to humans. They pose a potential bioterrorism threat because they cause botulism, a flaccid muscular paralysis-associated disease that requires immediate antitoxin treatment and intensive care over a long period of time. In addition to the existing seven established BoNT serotypes (BoNT/A–G), a new mosaic toxin type termed BoNT/HA (aka type FA or H) was reported recently. Sequence analyses indicate that the receptor-binding domain (HC) of BoNT/HA is ~84% identical to that of BoNT/A1. However, BoNT/HA responds differently to some potent BoNT/A-neutralizing antibodies (e.g., CR2) that target the HC. Therefore, it raises a serious concern as to whether BoNT/HA poses a new threat to our biosecurity. In this study, we report the first high-resolution crystal structure of BoNT/HA-HC at 1.8 Å. Sequence and structure analyses reveal that BoNT/HA and BoNT/A1 are different regarding their binding to cell-surface receptors including both polysialoganglioside (PSG) and synaptic vesicle glycoprotein 2 (SV2). Furthermore, the new structure also provides explanations for the ~540-fold decreased affinity of antibody CR2 towards BoNT/HA compared to BoNT/A1. Taken together, these new findings advance our understanding of the structure and function of this newly identified toxin at the molecular level, and pave the way for the future development of more effective countermeasures. Full article
(This article belongs to the Section Bacterial Toxins)
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Open AccessEditor’s ChoiceArticle Plasma-Based Degradation of Mycotoxins Produced by Fusarium, Aspergillus and Alternaria Species
Toxins 2017, 9(3), 97; doi:10.3390/toxins9030097
Received: 13 January 2017 / Revised: 28 February 2017 / Accepted: 7 March 2017 / Published: 10 March 2017
Cited by 3 | PDF Full-text (1960 KB) | HTML Full-text | XML Full-text
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The efficacy of cold atmospheric pressure plasma (CAPP) with ambient air as working gas for the degradation of selected mycotoxins was studied. Deoxynivalenol, zearalenone, enniatins, fumonisin B1, and T2 toxin produced by Fusarium spp., sterigmatocystin produced by Aspergillus spp. and AAL toxin produced
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The efficacy of cold atmospheric pressure plasma (CAPP) with ambient air as working gas for the degradation of selected mycotoxins was studied. Deoxynivalenol, zearalenone, enniatins, fumonisin B1, and T2 toxin produced by Fusarium spp., sterigmatocystin produced by Aspergillus spp. and AAL toxin produced by Alternaria alternata were used. The kinetics of the decay of mycotoxins exposed to plasma discharge was monitored. All pure mycotoxins exposed to CAPP were degraded almost completely within 60 s. Degradation rates varied with mycotoxin structure: fumonisin B1 and structurally related AAL toxin were degraded most rapidly while sterigmatocystin exhibited the highest resistance to degradation. As compared to pure compounds, the degradation rates of mycotoxins embedded in extracts of fungal cultures on rice were reduced to a varying extent. Our results show that CAPP efficiently degrades pure mycotoxins, the degradation rates vary with mycotoxin structure, and the presence of matrix slows down yet does not prevent the degradation. CAPP appears promising for the decontamination of food commodities with mycotoxins confined to or enriched on surfaces such as cereal grains. Full article
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Open AccessEditor’s ChoiceArticle How the Cobra Got Its Flesh-Eating Venom: Cytotoxicity as a Defensive Innovation and Its Co-Evolution with Hooding, Aposematic Marking, and Spitting
Toxins 2017, 9(3), 103; doi:10.3390/toxins9030103
Received: 23 January 2017 / Revised: 19 February 2017 / Accepted: 5 March 2017 / Published: 13 March 2017
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The cytotoxicity of the venom of 25 species of Old World elapid snake was tested and compared with the morphological and behavioural adaptations of hooding and spitting. We determined that, contrary to previous assumptions, the venoms of spitting species are not consistently more
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The cytotoxicity of the venom of 25 species of Old World elapid snake was tested and compared with the morphological and behavioural adaptations of hooding and spitting. We determined that, contrary to previous assumptions, the venoms of spitting species are not consistently more cytotoxic than those of closely related non-spitting species. While this correlation between spitting and non-spitting was found among African cobras, it was not present among Asian cobras. On the other hand, a consistent positive correlation was observed between cytotoxicity and utilisation of the defensive hooding display that cobras are famous for. Hooding and spitting are widely regarded as defensive adaptations, but it has hitherto been uncertain whether cytotoxicity serves a defensive purpose or is somehow useful in prey subjugation. The results of this study suggest that cytotoxicity evolved primarily as a defensive innovation and that it has co-evolved twice alongside hooding behavior: once in the Hemachatus + Naja and again independently in the king cobras (Ophiophagus). There was a significant increase of cytotoxicity in the Asian Naja linked to the evolution of bold aposematic hood markings, reinforcing the link between hooding and the evolution of defensive cytotoxic venoms. In parallel, lineages with increased cytotoxicity but lacking bold hood patterns evolved aposematic markers in the form of high contrast body banding. The results also indicate that, secondary to the evolution of venom rich in cytotoxins, spitting has evolved three times independently: once within the African Naja, once within the Asian Naja, and once in the Hemachatus genus. The evolution of cytotoxic venom thus appears to facilitate the evolution of defensive spitting behaviour. In contrast, a secondary loss of cytotoxicity and reduction of the hood occurred in the water cobra Naja annulata, which possesses streamlined neurotoxic venom similar to that of other aquatic elapid snakes (e.g., hydrophiine sea snakes). The results of this study make an important contribution to our growing understanding of the selection pressures shaping the evolution of snake venom and its constituent toxins. The data also aid in elucidating the relationship between these selection pressures and the medical impact of human snakebite in the developing world, as cytotoxic cobras cause considerable morbidity including loss-of-function injuries that result in economic and social burdens in the tropics of Asia and sub-Saharan Africa. Full article
(This article belongs to the Special Issue Animal Venoms and Pain)
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Open AccessEditor’s ChoiceArticle Cubozoan Sting-Site Seawater Rinse, Scraping, and Ice Can Increase Venom Load: Upending Current First Aid Recommendations
Toxins 2017, 9(3), 105; doi:10.3390/toxins9030105
Received: 3 February 2017 / Revised: 9 March 2017 / Accepted: 13 March 2017 / Published: 15 March 2017
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Cnidarian envenomations are the leading cause of severe and lethal human sting injuries from marine life. The total amount of venom discharged into sting-site tissues, sometimes referred to as “venom load”, has been previously shown to correlate with tentacle contact length and sequelae
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Cnidarian envenomations are the leading cause of severe and lethal human sting injuries from marine life. The total amount of venom discharged into sting-site tissues, sometimes referred to as “venom load”, has been previously shown to correlate with tentacle contact length and sequelae severity. Since <1% of cnidae discharge upon initial tentacle contact, effective and safe removal of adherent tentacles is of paramount importance in the management of life-threatening cubozoan stings. We evaluated whether common rinse solutions or scraping increased venom load as measured in a direct functional assay of venom activity (hemolysis). Scraping significantly increased hemolysis by increasing cnidae discharge. For Alatina alata, increases did not occur if the tentacles were first doused with vinegar or if heat was applied. However, in Chironex fleckeri, vinegar dousing and heat treatment were less effective, and the best outcomes occurred with the use of venom-inhibiting technologies (Sting No More® products). Seawater rinsing, considered a “no-harm” alternative, significantly increased venom load. The application of ice severely exacerbated A. alata stings, but had a less pronounced effect on C. fleckeri stings, while heat application markedly reduced hemolysis for both species. Our results do not support scraping or seawater rinsing to remove adherent tentacles. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessEditor’s ChoiceArticle Venom Profiling of a Population of the Theraphosid Spider Phlogius crassipes Reveals Continuous Ontogenetic Changes from Juveniles through Adulthood
Toxins 2017, 9(4), 116; doi:10.3390/toxins9040116
Received: 3 February 2017 / Revised: 27 February 2017 / Accepted: 5 March 2017 / Published: 25 March 2017
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Abstract
Theraphosid spiders (tarantulas) are venomous arthropods found in most tropical and subtropical regions of the world. Tarantula venoms are a complex cocktail of toxins with potential use as pharmacological tools, drugs and bioinsecticides. Although numerous toxins have been isolated from tarantula venoms, little
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Theraphosid spiders (tarantulas) are venomous arthropods found in most tropical and subtropical regions of the world. Tarantula venoms are a complex cocktail of toxins with potential use as pharmacological tools, drugs and bioinsecticides. Although numerous toxins have been isolated from tarantula venoms, little research has been carried out on the venom of Australian tarantulas. We therefore investigated the venom profile of the Australian theraphosid spider Phlogius crassipes and examined whether there are ontogenetic changes in venom composition. Spiders were divided into four ontogenic groups according to cephalothorax length, then the venom composition of each group was examined using gel electrophoresis and mass spectrometry. We found that the venom of P. crassipes changes continuously during development and throughout adulthood. Our data highlight the need to investigate the venom of organisms over the course of their lives to uncover and understand the changing functions of venom and the full range of toxins expressed. This in turn should lead to a deeper understanding of the organism’s ecology and enhance the potential for biodiscovery. Full article
(This article belongs to the collection Evolution of Venom Systems)
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Open AccessEditor’s ChoiceArticle Changes in the Fusarium Head Blight Complex of Malting Barley in a Three-Year Field Experiment in Italy
Toxins 2017, 9(4), 120; doi:10.3390/toxins9040120
Received: 6 February 2017 / Revised: 23 March 2017 / Accepted: 24 March 2017 / Published: 29 March 2017
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Abstract
In this study, conducted for three years on eleven malting barley varieties cultivated in central Italy, the incidence of different mycotoxigenic fungal genera, the identification of the Fusarium species associated with the Fusarium Head Blight (FHB) complex, and kernels contamination with deoxynivalenol (DON)
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In this study, conducted for three years on eleven malting barley varieties cultivated in central Italy, the incidence of different mycotoxigenic fungal genera, the identification of the Fusarium species associated with the Fusarium Head Blight (FHB) complex, and kernels contamination with deoxynivalenol (DON) and T-2 mycotoxins were determined. The influence of climatic conditions on Fusarium infections and FHB complex composition was also investigated. Fusarium species were always present in the three years and the high average and maximum temperatures during anthesis mainly favored their occurrence. The FHB complex was subject to changes during the three years and the main causal agents were F. poae, F. avenaceum, F. tricinctum and F. graminearum, which, even if constantly present, never represented the principal FHB agent. The relative incidence of Fusarium species changed because of climatic conditions occurring during the seasons. The FHB complex was composed of many different Fusarium species and some of them were associated with a specific variety and/or with specific weather parameters, indicating that the interaction between a certain plant genotype and climatic conditions may influence the presence of Fusarium spp. causing infections. With regard to mycotoxin contamination, T-2 toxin, in some cases, was found in kernels at levels that exceeded EU recommended values. Full article
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Open AccessFeature PaperEditor’s ChoiceArticle Insights into the Structure of the Vip3Aa Insecticidal Protein by Protease Digestion Analysis
Toxins 2017, 9(4), 131; doi:10.3390/toxins9040131
Received: 14 March 2017 / Revised: 28 March 2017 / Accepted: 4 April 2017 / Published: 7 April 2017
Cited by 5 | PDF Full-text (1780 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Vip3 proteins are secretable proteins from Bacillus thuringiensis whose mode of action is still poorly understood. In this study, the activation process for Vip3 proteins was closely examined in order to better understand the Vip3Aa protein stability and to shed light on its
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Vip3 proteins are secretable proteins from Bacillus thuringiensis whose mode of action is still poorly understood. In this study, the activation process for Vip3 proteins was closely examined in order to better understand the Vip3Aa protein stability and to shed light on its structure. The Vip3Aa protoxin (of 89 kDa) was treated with trypsin at concentrations from 1:100 to 120:100 (trypsin:Vip3A, w:w). If the action of trypsin was not properly neutralized, the results of SDS-PAGE analysis (as well as those with Agrotis ipsilon midgut juice) equivocally indicated that the protoxin could be completely processed. However, when the proteolytic reaction was efficiently stopped, it was revealed that the protoxin was only cleaved at a primary cleavage site, regardless of the amount of trypsin used. The 66 kDa and the 19 kDa peptides generated by the proteases co-eluted after gel filtration chromatography, indicating that they remain together after cleavage. The 66 kDa fragment was found to be extremely resistant to proteases. The trypsin treatment of the protoxin in the presence of SDS revealed the presence of secondary cleavage sites at S-509, and presumably at T-466 and V-372, rendering C-terminal fragments of approximately 29, 32, and 42 kDa, respectively. The fact that the predicted secondary structure of the Vip3Aa protein shows a cluster of beta sheets in the C-terminal region of the protein might be the reason behind the higher stability to proteases compared to the rest of the protein, which is mainly composed of alpha helices. Full article
(This article belongs to the Special Issue The Insecticidal Bacterial Toxins in Modern Agriculture)
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Open AccessEditor’s ChoiceArticle 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
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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 AccessFeature PaperEditor’s ChoiceArticle 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
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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 AccessEditor’s ChoiceArticle 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
Cited by 2 | PDF Full-text (3160 KB) | HTML Full-text | XML Full-text | Supplementary Files
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 AccessEditor’s ChoiceArticle 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 AccessEditor’s ChoiceArticle Venom On-a-Chip: A Fast and Efficient Method for Comparative Venomics
Toxins 2017, 9(6), 179; doi:10.3390/toxins9060179
Received: 20 April 2017 / Revised: 23 May 2017 / Accepted: 24 May 2017 / Published: 28 May 2017
Cited by 1 | PDF Full-text (2919 KB) | HTML Full-text | XML Full-text
Abstract
Venom research has attracted an increasing interest in disparate fields, from drug development and pharmacology, to evolutionary biology and ecology, and rational antivenom production. Advances in “-omics” technologies have allowed the characterization of an increasing number of animal venoms, but the methodology currently
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Venom research has attracted an increasing interest in disparate fields, from drug development and pharmacology, to evolutionary biology and ecology, and rational antivenom production. Advances in “-omics” technologies have allowed the characterization of an increasing number of animal venoms, but the methodology currently available is suboptimal for large-scale comparisons of venom profiles. Here, we describe a fast, reproducible and semi-automated protocol for investigating snake venom variability, especially at the intraspecific level, using the Agilent Bioanalyzer on-chip technology. Our protocol generated a phenotype matrix which can be used for robust statistical analysis and correlations of venom variation with ecological correlates, or other extrinsic factors. We also demonstrate the ease and utility of combining on-chip technology with previously fractionated venoms for detection of specific individual toxin proteins. Our study describes a novel strategy for rapid venom discrimination and analysis of compositional variation at multiple taxonomic levels, allowing researchers to tackle evolutionary questions and unveiling the drivers of the incredible biodiversity of venoms. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessEditor’s ChoiceArticle Prevalence, Variability and Bioconcentration of Saxitoxin-Group in Different Marine Species Present in the Food Chain
Toxins 2017, 9(6), 190; doi:10.3390/toxins9060190
Received: 17 May 2017 / Revised: 7 June 2017 / Accepted: 8 June 2017 / Published: 12 June 2017
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Abstract
The saxitoxin-group (STX-group) corresponds to toxic metabolites produced by cyanobacteria and dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium. Over the last decade, it has been possible to extrapolate the areas contaminated with the STX-group worldwide, including Chile, a phenomenon that
[...] Read more.
The saxitoxin-group (STX-group) corresponds to toxic metabolites produced by cyanobacteria and dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium. Over the last decade, it has been possible to extrapolate the areas contaminated with the STX-group worldwide, including Chile, a phenomenon that has affected ≈35% of the Southern Pacific coast territory, generating a high economic impact. The objective of this research was to study the toxicity of the STX-group in all aquatic organisms (bivalves, algae, echinoderms, crustaceans, tunicates, cephalopods, gastropods, and fish) present in areas with a variable presence of harmful algal blooms (HABs). Then, the toxic profiles of each species and dose of STX equivalents ingested by a 60 kg person from 400 g of shellfish were determined to establish the health risk assessment. The toxins with the highest prevalence detected were gonyautoxin-4/1 (GTX4/GTX1), gonyautoxin-3/2 (GTX3/GTX2), neosaxitoxin (neoSTX), decarbamoylsaxitoxin (dcSTX), and saxitoxin (STX), with average concentrations of 400, 2800, 280, 200, and 2000 µg kg−1 respectively, a species-specific variability, dependent on the evaluated tissue, which demonstrates the biotransformation of the analogues in the trophic transfer with a predominance of α-epimers in all toxic profiles. The identification in multiple vectors, as well as in unregulated species, suggests that a risk assessment and risk management update are required; also, chemical and specific analyses for the detection of all analogues associated with the STX-group need to be established. Full article
(This article belongs to the Special Issue Public Health Outreach to Prevention of Aquatic Toxin Exposure)
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Open AccessEditor’s ChoiceArticle Evaluation of Cyanea capillata Sting Management Protocols Using Ex Vivo and In Vitro Envenomation Models
Toxins 2017, 9(7), 215; doi:10.3390/toxins9070215
Received: 2 June 2017 / Revised: 27 June 2017 / Accepted: 3 July 2017 / Published: 7 July 2017
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Abstract
Lion’s mane jellyfish (Cyanea capillata) stings cause severe pain and can lead to dangerous systemic effects, including Irukandji-like syndrome. As is the case for most cnidarian stings, recommended medical protocols in response to such stings lack rigorous scientific support. In this
[...] Read more.
Lion’s mane jellyfish (Cyanea capillata) stings cause severe pain and can lead to dangerous systemic effects, including Irukandji-like syndrome. As is the case for most cnidarian stings, recommended medical protocols in response to such stings lack rigorous scientific support. In this study, we sought to evaluate potential first aid care protocols using previously described envenomation models that allow for direct measurements of venom activity. We found that seawater rinsing, the most commonly recommended method of tentacle removal for this species, induced significant increases in venom delivery, while rinsing with vinegar or Sting No More® Spray did not. Post-sting temperature treatments affected sting severity, with 40 min of hot-pack treatment reducing lysis of sheep’s blood (in agar plates), a direct representation of venom load, by over 90%. Ice pack treatment had no effect on sting severity. These results indicate that sting management protocols for Cyanea need to be revised immediately to discontinue rinsing with seawater and include the use of heat treatment. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessEditor’s ChoiceArticle The Mode of Action of Cyclo(l-Ala-l-Pro) in Inhibiting Aflatoxin Production of Aspergillus flavus
Toxins 2017, 9(7), 219; doi:10.3390/toxins9070219
Received: 21 June 2017 / Accepted: 11 July 2017 / Published: 12 July 2017
Cited by 1 | PDF Full-text (1651 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyclo(l-Ala-l-Pro) inhibits aflatoxin production in aflatoxigenic fungi without affecting fungal growth. The mode of action of cyclo(l-Ala-l-Pro) in inhibiting aflatoxin production of Aspergillus flavus was investigated. A glutathione S-transferase (GST) of the fungus, designated
[...] Read more.
Cyclo(l-Ala-l-Pro) inhibits aflatoxin production in aflatoxigenic fungi without affecting fungal growth. The mode of action of cyclo(l-Ala-l-Pro) in inhibiting aflatoxin production of Aspergillus flavus was investigated. A glutathione S-transferase (GST) of the fungus, designated AfGST, was identified as a binding protein of cyclo(l-Ala-l-Pro) in an experiment performed using cyclo(l-Ala-l-Pro)-immobilized Sepharose beads. Cyclo(l-Ala-l-Pro) specifically bound to recombinant AfGST and inhibited its GST activity. Ethacrynic acid, a known GST inhibitor, inhibited the GST activity of recombinant AfGST and aflatoxin production of the fungus. Ethacrynic acid reduced the expression level of AflR, a key regulatory protein for aflatoxin production, similar to cyclo(l-Ala-l-Pro). These results suggest that cyclo(l-Ala-l-Pro) inhibits aflatoxin production by affecting GST function in A. flavus, and that AfGST inhibitors are possible candidates as selective aflatoxin production inhibitors. Full article
(This article belongs to the collection Aflatoxins)
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Open AccessEditor’s ChoiceArticle Enter the Dragon: The Dynamic and Multifunctional Evolution of Anguimorpha Lizard Venoms
Toxins 2017, 9(8), 242; doi:10.3390/toxins9080242
Received: 5 June 2017 / Revised: 4 August 2017 / Accepted: 4 August 2017 / Published: 6 August 2017
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Abstract
While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition
[...] Read more.
While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds. Full article
(This article belongs to the collection Evolution of Venom Systems)
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Open AccessEditor’s ChoiceReview Forthcoming Challenges in Mycotoxins Toxicology Research for Safer Food—A Need for Multi-Omics Approach
Toxins 2017, 9(1), 18; doi:10.3390/toxins9010018
Received: 4 November 2016 / Revised: 29 December 2016 / Accepted: 2 January 2017 / Published: 4 January 2017
Cited by 2 | PDF Full-text (957 KB) | HTML Full-text | XML Full-text
Abstract
The presence of mycotoxins in food represents a severe threat for public health and welfare, and poses relevant research challenges in the food toxicology field. Nowadays, food toxicologists have to provide answers to food-related toxicological issues, but at the same time they should
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The presence of mycotoxins in food represents a severe threat for public health and welfare, and poses relevant research challenges in the food toxicology field. Nowadays, food toxicologists have to provide answers to food-related toxicological issues, but at the same time they should provide the appropriate knowledge in background to effectively support the evidence-based decision-making in food safety. Therefore, keeping in mind that regulatory actions should be based on sound scientific findings, the present opinion addresses the main challenges in providing reliable data for supporting the risk assessment of foodborne mycotoxins. Full article
(This article belongs to the collection Leading Opinions (Closed))
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Open AccessEditor’s ChoiceReview Historical Perspectives and Guidelines for Botulinum Neurotoxin Subtype Nomenclature
Toxins 2017, 9(1), 38; doi:10.3390/toxins9010038
Received: 9 December 2016 / Revised: 4 January 2017 / Accepted: 7 January 2017 / Published: 18 January 2017
Cited by 12 | PDF Full-text (2110 KB) | HTML Full-text | XML Full-text
Abstract
Botulinum neurotoxins are diverse proteins. They are currently represented by at least seven serotypes and more than 40 subtypes. New clostridial strains that produce novel neurotoxin variants are being identified with increasing frequency, which presents challenges when organizing the nomenclature surrounding these neurotoxins.
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Botulinum neurotoxins are diverse proteins. They are currently represented by at least seven serotypes and more than 40 subtypes. New clostridial strains that produce novel neurotoxin variants are being identified with increasing frequency, which presents challenges when organizing the nomenclature surrounding these neurotoxins. Worldwide, researchers are faced with the possibility that toxins having identical sequences may be given different designations or novel toxins having unique sequences may be given the same designations on publication. In order to minimize these problems, an ad hoc committee consisting of over 20 researchers in the field of botulinum neurotoxin research was convened to discuss the clarification of the issues involved in botulinum neurotoxin nomenclature. This publication presents a historical overview of the issues and provides guidelines for botulinum neurotoxin subtype nomenclature in the future. Full article
(This article belongs to the Section Bacterial Toxins)
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Open AccessEditor’s ChoiceReview Protection against Shiga Toxins
Toxins 2017, 9(2), 44; doi:10.3390/toxins9020044
Received: 29 December 2016 / Revised: 18 January 2017 / Accepted: 19 January 2017 / Published: 3 February 2017
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Abstract
Shiga toxins consist of an A-moiety and five B-moieties able to bind the neutral glycosphingolipid globotriaosylceramide (Gb3) on the cell surface. To intoxicate cells efficiently, the toxin A-moiety has to be cleaved by furin and transported retrogradely to the Golgi apparatus and to
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Shiga toxins consist of an A-moiety and five B-moieties able to bind the neutral glycosphingolipid globotriaosylceramide (Gb3) on the cell surface. To intoxicate cells efficiently, the toxin A-moiety has to be cleaved by furin and transported retrogradely to the Golgi apparatus and to the endoplasmic reticulum. The enzymatically active part of the A-moiety is then translocated to the cytosol, where it inhibits protein synthesis and in some cell types induces apoptosis. Protection of cells can be provided either by inhibiting binding of the toxin to cells or by interfering with any of the subsequent steps required for its toxic effect. In this article we provide a brief overview of the interaction of Shiga toxins with cells, describe some compounds and conditions found to protect cells against Shiga toxins, and discuss whether they might also provide protection in animals and humans. Full article
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Open AccessEditor’s ChoiceReview Fungal Ribotoxins: A Review of Potential Biotechnological Applications
Toxins 2017, 9(2), 71; doi:10.3390/toxins9020071
Received: 11 January 2017 / Revised: 14 February 2017 / Accepted: 16 February 2017 / Published: 21 February 2017
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Abstract
Fungi establish a complex network of biological interactions with other organisms in nature. In many cases, these involve the production of toxins for survival or colonization purposes. Among these toxins, ribotoxins stand out as promising candidates for their use in biotechnological applications. They
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Fungi establish a complex network of biological interactions with other organisms in nature. In many cases, these involve the production of toxins for survival or colonization purposes. Among these toxins, ribotoxins stand out as promising candidates for their use in biotechnological applications. They constitute a group of highly specific extracellular ribonucleases that target a universally conserved sequence of RNA in the ribosome, the sarcin-ricin loop. The detailed molecular study of this family of toxic proteins over the past decades has highlighted their potential in applied research. Remarkable examples would be the recent studies in the field of cancer research with promising results involving ribotoxin-based immunotoxins. On the other hand, some ribotoxin-producer fungi have already been studied in the control of insect pests. The recent role of ribotoxins as insecticides could allow their employment in formulas and even as baculovirus-based biopesticides. Moreover, considering the important role of their target in the ribosome, they can be used as tools to study how ribosome biogenesis is regulated and, eventually, may contribute to a better understanding of some ribosomopathies. Full article
(This article belongs to the Section Mycotoxins)
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Open AccessFeature PaperEditor’s ChoiceReview The Biology of Pichia membranifaciens Killer Toxins
Toxins 2017, 9(4), 112; doi:10.3390/toxins9040112
Received: 10 February 2017 / Revised: 7 March 2017 / Accepted: 20 March 2017 / Published: 23 March 2017
Cited by 4 | PDF Full-text (3078 KB) | HTML Full-text | XML Full-text
Abstract
The killer phenomenon is defined as the ability of some yeast to secrete toxins that are lethal to other sensitive yeasts and filamentous fungi. Since the discovery of strains of Saccharomyces cerevisiae capable of secreting killer toxins, much information has been gained regarding
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The killer phenomenon is defined as the ability of some yeast to secrete toxins that are lethal to other sensitive yeasts and filamentous fungi. Since the discovery of strains of Saccharomyces cerevisiae capable of secreting killer toxins, much information has been gained regarding killer toxins and this fact has substantially contributed knowledge on fundamental aspects of cell biology and yeast genetics. The killer phenomenon has been studied in Pichia membranifaciens for several years, during which two toxins have been described. PMKT and PMKT2 are proteins of low molecular mass that bind to primary receptors located in the cell wall structure of sensitive yeast cells, linear (1→6)-β-d-glucans and mannoproteins for PMKT and PMKT2, respectively. Cwp2p also acts as a secondary receptor for PMKT. Killing of sensitive cells by PMKT is characterized by ionic movements across plasma membrane and an acidification of the intracellular pH triggering an activation of the High Osmolarity Glycerol (HOG) pathway. On the contrary, our investigations showed a mechanism of killing in which cells are arrested at an early S-phase by high concentrations of PMKT2. However, we concluded that induced mortality at low PMKT2 doses and also PMKT is indeed of an apoptotic nature. Killer yeasts and their toxins have found potential applications in several fields: in food and beverage production, as biocontrol agents, in yeast bio-typing, and as novel antimycotic agents. Accordingly, several applications have been found for P. membranifaciens killer toxins, ranging from pre- and post-harvest biocontrol of plant pathogens to applications during wine fermentation and ageing (inhibition of Botrytis cinerea, Brettanomyces bruxellensis, etc.). Full article
(This article belongs to the Special Issue Yeast Killer Toxins)
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Open AccessEditor’s ChoiceReview Type IV Secretion and Signal Transduction of Helicobacter pylori CagA through Interactions with Host Cell Receptors
Toxins 2017, 9(4), 115; doi:10.3390/toxins9040115
Received: 29 January 2017 / Revised: 20 March 2017 / Accepted: 22 March 2017 / Published: 24 March 2017
Cited by 1 | PDF Full-text (1573 KB) | HTML Full-text | XML Full-text
Abstract
Helicobacter pylori is a highly successful human bacterium, which is exceptionally equipped to persistently inhabit the human stomach. Colonization by this pathogen is associated with gastric disorders ranging from chronic gastritis and peptic ulcers to cancer. Highly virulent H. pylori strains express the
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Helicobacter pylori is a highly successful human bacterium, which is exceptionally equipped to persistently inhabit the human stomach. Colonization by this pathogen is associated with gastric disorders ranging from chronic gastritis and peptic ulcers to cancer. Highly virulent H. pylori strains express the well-established adhesins BabA/B, SabA, AlpA/B, OipA, and HopQ, and a type IV secretion system (T4SS) encoded by the cag pathogenicity island (PAI). The adhesins ascertain intimate bacterial contact to gastric epithelial cells, while the T4SS represents an extracellular pilus-like structure for the translocation of the effector protein CagA. Numerous T4SS components including CagI, CagL, CagY, and CagA have been shown to target the integrin-β1 receptor followed by translocation of CagA across the host cell membrane. The interaction of CagA with membrane-anchored phosphatidylserine and CagA-containing outer membrane vesicles may also play a role in the delivery process. Translocated CagA undergoes tyrosine phosphorylation in C-terminal EPIYA-repeat motifs by oncogenic Src and Abl kinases. CagA then interacts with an array of host signaling proteins followed by their activation or inactivation in phosphorylation-dependent and phosphorylation-independent fashions. We now count about 25 host cell binding partners of intracellular CagA, which represent the highest quantity of all currently known virulence-associated effector proteins in the microbial world. Here we review the research progress in characterizing interactions of CagA with multiple host cell receptors in the gastric epithelium, including integrin-β1, EGFR, c-Met, CD44, E-cadherin, and gp130. The contribution of these interactions to H. pylori colonization, signal transduction, and gastric pathogenesis is discussed. Full article
(This article belongs to the Special Issue H. pylori Virulence Factors in the Induction of Gastric Cancer)
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Open AccessEditor’s ChoiceReview Proteolysis in Helicobacter pylori-Induced Gastric Cancer
Toxins 2017, 9(4), 134; doi:10.3390/toxins9040134
Received: 14 February 2017 / Revised: 3 April 2017 / Accepted: 6 April 2017 / Published: 11 April 2017
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Abstract
Persistent infections with the human pathogen and class-I carcinogen Helicobacter pylori (H. pylori) are closely associated with the development of acute and chronic gastritis, ulceration, gastric adenocarcinoma and lymphoma of the mucosa-associated lymphoid tissue (MALT) system. Disruption and depolarization of the
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Persistent infections with the human pathogen and class-I carcinogen Helicobacter pylori (H. pylori) are closely associated with the development of acute and chronic gastritis, ulceration, gastric adenocarcinoma and lymphoma of the mucosa-associated lymphoid tissue (MALT) system. Disruption and depolarization of the epithelium is a hallmark of H. pylori-associated disorders and requires extensive modulation of epithelial cell surface structures. Hence, the complex network of controlled proteolysis which facilitates tissue homeostasis in healthy individuals is deregulated and crucially contributes to the induction and progression of gastric cancer through processing of extracellular matrix (ECM) proteins, cell surface receptors, membrane-bound cytokines, and lateral adhesion molecules. Here, we summarize the recent reports on mechanisms how H. pylori utilizes a variety of extracellular proteases, involving the proteases Hp0169 and high temperature requirement A (HtrA) of bacterial origin, and host matrix-metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs) and tissue inhibitors of metalloproteinases (TIMPs). H. pylori-regulated proteases represent predictive biomarkers and attractive targets for therapeutic interventions in gastric cancer. Full article
(This article belongs to the Special Issue H. pylori Virulence Factors in the Induction of Gastric Cancer)
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Open AccessEditor’s ChoiceReview Toxins of Prokaryotic Toxin-Antitoxin Systems with Sequence-Specific Endoribonuclease Activity
Toxins 2017, 9(4), 140; doi:10.3390/toxins9040140
Received: 15 February 2017 / Revised: 9 April 2017 / Accepted: 10 April 2017 / Published: 14 April 2017
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Abstract
Protein translation is the most common target of toxin-antitoxin system (TA) toxins. Sequence-specific endoribonucleases digest RNA in a sequence-specific manner, thereby blocking translation. While past studies mainly focused on the digestion of mRNA, recent analysis revealed that toxins can also digest tRNA, rRNA
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Protein translation is the most common target of toxin-antitoxin system (TA) toxins. Sequence-specific endoribonucleases digest RNA in a sequence-specific manner, thereby blocking translation. While past studies mainly focused on the digestion of mRNA, recent analysis revealed that toxins can also digest tRNA, rRNA and tmRNA. Purified toxins can digest single-stranded portions of RNA containing recognition sequences in the absence of ribosome in vitro. However, increasing evidence suggests that in vivo digestion may occur in association with ribosomes. Despite the prevalence of recognition sequences in many mRNA, preferential digestion seems to occur at specific positions within mRNA and also in certain reading frames. In this review, a variety of tools utilized to study the nuclease activities of toxins over the past 15 years will be reviewed. A recent adaptation of an RNA-seq-based technique to analyze entire sets of cellular RNA will be introduced with an emphasis on its strength in identifying novel targets and redefining recognition sequences. The differences in biochemical properties and postulated physiological roles will also be discussed. Full article
(This article belongs to the Section Bacterial Toxins)
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Open AccessEditor’s ChoiceReview 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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Open AccessEditor’s ChoiceReview Structural Features of Apicomplexan Pore-Forming Proteins and Their Roles in Parasite Cell Traversal and Egress
Toxins 2017, 9(9), 265; doi:10.3390/toxins9090265
Received: 2 August 2017 / Revised: 20 August 2017 / Accepted: 22 August 2017 / Published: 29 August 2017
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Abstract
Apicomplexan parasites cause diseases, including malaria and toxoplasmosis, in a range of hosts, including humans. These intracellular parasites utilize pore-forming proteins that disrupt host cell membranes to either traverse host cells while migrating through tissues or egress from the parasite-containing vacuole after replication.
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Apicomplexan parasites cause diseases, including malaria and toxoplasmosis, in a range of hosts, including humans. These intracellular parasites utilize pore-forming proteins that disrupt host cell membranes to either traverse host cells while migrating through tissues or egress from the parasite-containing vacuole after replication. This review highlights recent insight gained from the newly available three-dimensional structures of several known or putative apicomplexan pore-forming proteins that contribute to cell traversal or egress. These new structural advances suggest that parasite pore-forming proteins use distinct mechanisms to disrupt host cell membranes at multiple steps in parasite life cycles. How proteolytic processing, secretion, environment, and the accessibility of lipid receptors regulate the membranolytic activities of such proteins is also discussed. Full article
(This article belongs to the Special Issue Cellular Entry of Binary and Pore-Forming Bacterial Toxins)
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Open AccessEditor’s ChoiceReview A Review and Database of Snake Venom Proteomes
Toxins 2017, 9(9), 290; doi:10.3390/toxins9090290
Received: 1 September 2017 / Revised: 15 September 2017 / Accepted: 15 September 2017 / Published: 18 September 2017
PDF Full-text (2615 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Advances in the last decade combining transcriptomics with established proteomics methods have made possible rapid identification and quantification of protein families in snake venoms. Although over 100 studies have been published, the value of this information is increased when it is collated, allowing
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Advances in the last decade combining transcriptomics with established proteomics methods have made possible rapid identification and quantification of protein families in snake venoms. Although over 100 studies have been published, the value of this information is increased when it is collated, allowing rapid assimilation and evaluation of evolutionary trends, geographical variation, and possible medical implications. This review brings together all compositional studies of snake venom proteomes published in the last decade. Compositional studies were identified for 132 snake species: 42 from 360 (12%) Elapidae (elapids), 20 from 101 (20%) Viperinae (true vipers), 65 from 239 (27%) Crotalinae (pit vipers), and five species of non-front-fanged snakes. Approximately 90% of their total venom composition consisted of eight protein families for elapids, 11 protein families for viperines and ten protein families for crotalines. There were four dominant protein families: phospholipase A2s (the most common across all front-fanged snakes), metalloproteases, serine proteases and three-finger toxins. There were six secondary protein families: cysteine-rich secretory proteins, l-amino acid oxidases, kunitz peptides, C-type lectins/snaclecs, disintegrins and natriuretic peptides. Elapid venoms contained mostly three-finger toxins and phospholipase A2s and viper venoms metalloproteases, phospholipase A2s and serine proteases. Although 63 protein families were identified, more than half were present in <5% of snake species studied and always in low abundance. The importance of these minor component proteins remains unknown. Full article
(This article belongs to the Section Animal Venoms)
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Open AccessEditor’s ChoiceLetter Is the Insect World Overcoming the Efficacy of Bacillus thuringiensis?
Toxins 2017, 9(1), 39; doi:10.3390/toxins9010039
Received: 16 November 2016 / Revised: 5 January 2017 / Accepted: 10 January 2017 / Published: 18 January 2017
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Abstract
The use of chemical pesticides revolutionized agriculture with the introduction of DDT (Dichlorodiphenyltrichloroethane) as the first modern chemical insecticide. However, the effectiveness of DDT and other synthetic pesticides, together with their low cost and ease of use, have led to the generation of
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The use of chemical pesticides revolutionized agriculture with the introduction of DDT (Dichlorodiphenyltrichloroethane) as the first modern chemical insecticide. However, the effectiveness of DDT and other synthetic pesticides, together with their low cost and ease of use, have led to the generation of undesirable side effects, such as pollution of water and food sources, harm to non-target organisms and the generation of insect resistance. The alternative comes from biological control agents, which have taken an expanding share in the pesticide market over the last decades mainly promoted by the necessity to move towards more sustainable agriculture. Among such biological control agents, the bacterium Bacillus thuringiensis (Bt) and its insecticidal toxins have been the most studied and commercially used biological control agents over the last 40 years. However, some insect pests have acquired field-evolved resistance to the most commonly used Bt-based pesticides, threatening their efficacy, which necessitates the immediate search for novel strains and toxins exhibiting different modes of action and specificities in order to perpetuate the insecticidal potential of this bacterium. Full article
(This article belongs to the Section Bacterial Toxins)
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Open AccessEditor’s ChoiceReply Reply to Comment on “Screening and Identification of Novel Ochratoxin A-Producing Fungi from Grapes”. Toxins 2016, 8, 333”–in Reporting Ochratoxin A Production from Strains of Aspergillus, Penicillium and Talaromyces
Toxins 2017, 9(2), 66; doi:10.3390/toxins9020066
Received: 8 February 2017 / Accepted: 8 February 2017 / Published: 14 February 2017
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(This article belongs to the collection Ochratoxins-Collection)
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