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 -
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
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Open AccessArticle
Initial Spore Density Has an Influence on Ochratoxin A Content in Aspergillus ochraceus CGMCC 3.4412 in PDB and Its Interaction with Seeds
Toxins 2017, 9(4), 146; doi:10.3390/toxins9040146 -
Abstract
The morphology and secondary metabolism of Aspergillus spp. are associated with initial spore density (ISD). Fatty acids (FA) are involved in the biosynthesis of aflatoxins (AF) through Aspergillus quorum sensing (QS). Here, we studied how ochratoxin A (OTA) was regulated by spore density
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The morphology and secondary metabolism of Aspergillus spp. are associated with initial spore density (ISD). Fatty acids (FA) are involved in the biosynthesis of aflatoxins (AF) through Aspergillus quorum sensing (QS). Here, we studied how ochratoxin A (OTA) was regulated by spore density in Aspergillus ochraceus CGMCC 3.4412. The results contribute to understanding the role of spore density in morphogenesis, OTA biosynthesis, and host–pathogen interactions. When A. ochraceus was grown in Potato Dextrose Broth (PDB) media at different spore densities (from 101 to 106 spores/mL), more OTA was produced when ISD were increased, but a higher level of ISD inhibited OTA biosynthesis. Seed infection studies showed that peanuts (Arachis hypogaea) and soybeans (Glycine max) with high FA content were more susceptible to OTA production when infected by A. ochraceus and reactive oxygen species (ROS)-induced OTA biosynthesis. These results suggested that FA was vital for OTA biosynthesis, and that oxidative stress was closely related to OTA biosynthesis in A. ochraceus. Full article
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Open AccessArticle
A Rapid Magnetic Solid Phase Extraction Method Followed by Liquid Chromatography-Tandem Mass Spectrometry Analysis for the Determination of Mycotoxins in Cereals
Toxins 2017, 9(4), 147; doi:10.3390/toxins9040147 -
Abstract
Mycotoxins can contaminate various food commodities, including cereals. Moreover, mycotoxins of different classes can co-contaminate food, increasing human health risk. Several analytical methods have been published in the literature dealing with mycotoxins determination in cereals. Nevertheless, in the present work, the aim was
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Mycotoxins can contaminate various food commodities, including cereals. Moreover, mycotoxins of different classes can co-contaminate food, increasing human health risk. Several analytical methods have been published in the literature dealing with mycotoxins determination in cereals. Nevertheless, in the present work, the aim was to propose an easy and effective system for the extraction of six of the main mycotoxins from corn meal and durum wheat flour, i.e., the main four aflatoxins, ochratoxin A, and the mycoestrogen zearalenone. The developed method exploited magnetic solid phase extraction (SPE), a technique that is attracting an increasing interest as an alternative to classical SPE. Therefore, the use of magnetic graphitized carbon black as a suitable extracting material was tested. The same magnetic material proved to be effective in the extraction of mycoestrogens from milk, but has never been applied to complex matrices as cereals. Ultra high–performance liquid chromatography tandem mass spectrometry was used for detection. Recoveries were >60% in both cereals, even if the matrix effects were not negligible. The limits of quantification of the method results were comparable to those obtained by other two magnetic SPE-based methods applied to cereals, which were limited to one or two mycotoxins, whereas in this work the investigated mycotoxins belonged to three different chemical classes. Full article
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Open AccessFeature PaperReview
Treatments for Latrodectism—A Systematic Review on Their Clinical Effectiveness
Toxins 2017, 9(4), 148; doi:10.3390/toxins9040148 -
Abstract
Latrodectism or envenomation by widow-spiders is common and clinically significant worldwide. Alpha-latrotoxin is the mammalian-specific toxin in the venom that results in toxic effects observed in humans. Symptoms may be incapacitating and include severe pain that can persist for days. The management of
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Latrodectism or envenomation by widow-spiders is common and clinically significant worldwide. Alpha-latrotoxin is the mammalian-specific toxin in the venom that results in toxic effects observed in humans. Symptoms may be incapacitating and include severe pain that can persist for days. The management of mild to moderate latrodectism is primarily supportive while severe cases have variously been treated with intravenous calcium, muscle relaxants, widow-spider antivenom and analgesic opioids. The object of this systematic review is to examine the literature on the clinical effectiveness of past and current treatments for latrodectism. MEDLINE, EMBASE and Google Scholar were searched from 1946 to December 2016 to identify clinical studies on the treatment of latrodectism. Studies older than 40 years and not in English were not reviewed. There were only two full-publications and one abstract of placebo-controlled randomised trials on antivenom use for latrodectism. Another two randomised comparative trials compared the route of administration of antivenom for latrodectism. There were fourteen case series (including two abstracts), fourteen case reports and one letter investigating drug treatments for latrodectism with the majority of these also including antivenom for severe latrodectism. Antivenom with opioid analgesia is often the major treatment reported for latrodectism however; recent high quality evidence has cast doubt on the clinical effectiveness of this combination and suggests that other treatments need to be investigated. Full article
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Open AccessArticle
A Simple and Specific Noncompetitive ELISA Method for HT-2 Toxin Detection
Toxins 2017, 9(4), 145; doi:10.3390/toxins9040145 -
Abstract
We developed an HT-2 toxin-specific simple ELISA format with a positive read-out. The assay is based on an anti-immune complex (IC) scFv antibody fragment, which is genetically fused with alkaline phosphatase (AP). The anti-IC antibody specifically recognizes the IC between a primary anti-HT-2
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We developed an HT-2 toxin-specific simple ELISA format with a positive read-out. The assay is based on an anti-immune complex (IC) scFv antibody fragment, which is genetically fused with alkaline phosphatase (AP). The anti-IC antibody specifically recognizes the IC between a primary anti-HT-2 toxin Fab fragment and an HT-2 toxin molecule. In the IC ELISA format, the sample is added together with the scFv-AP antibody to the ELISA plate coated with the primary antibody. After 15 min of incubation and a washing step, the ELISA response is read. A competitive ELISA including only the primary antibody recognizes both HT-2 and T-2 toxins. The anti-IC antibody makes the assay specific for HT-2 toxin, and the IC ELISA is over 10 times more sensitive compared to the competitive assay. Three different naturally contaminated matrices: wheat, barley and oats, were used to evaluate the assay performance with real samples. The corresponding limits of detection were 0.3 ng/mL (13 µg/kg), 0.1 ng/mL (4 µg/kg) and 0.3 ng/mL (16 µg/kg), respectively. The IC ELISA can be used for screening HT-2 toxin specifically and in relevant concentration ranges from all three tested grain matrices. Full article
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Open AccessArticle
Diabetogenic Effects of Ochratoxin A in Female Rats
Toxins 2017, 9(4), 144; doi:10.3390/toxins9040144 -
Abstract
In this study, the diabetogenic effects of long term Ochratoxin A (OTA) administration in rats were investigated, and its role in the etiology of diabetes mellitus (DM) was examined utilizing 42 female Wistar rats for these purposes. The rats were divided into three
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In this study, the diabetogenic effects of long term Ochratoxin A (OTA) administration in rats were investigated, and its role in the etiology of diabetes mellitus (DM) was examined utilizing 42 female Wistar rats for these purposes. The rats were divided into three different study and control groups according to the duration of the OTA administration. The rats received 45 μg OTA daily in their feed for 6, 9 and 24 weeks, respectively. Three control groups were also used for the same time periods. Blood and pancreatic tissue samples were collected during the necropsy at the end of the 6, 9 and 24 weeks. The plasma values of insulin, glucagon and glucose were determined for the study and control groups. Pancreatic lesions were evaluated via histopathological examination and insulin and glucagon expression in these lesions was subsequently determined using immunohistochemical methods. Statistically significant decreases in insulin levels were observed, in contrast to increases in blood glucagon and glucose levels. Histopathological examinations revealed slight to moderate degeneration in Langerhans islet cells in all OTA-treated groups. Immunohistochemistry of pancreatic tissue revealed decreased insulin and increased glucagon expression. This study demonstrated that OTA may cause pancreatic damage in the Langerhans islet and predispose rats to DM. Full article
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Open AccessFeature PaperReview
Antivenom for Neuromuscular Paralysis Resulting From Snake Envenoming
Toxins 2017, 9(4), 143; doi:10.3390/toxins9040143 -
Abstract
Antivenom therapy is currently the standard practice for treating neuromuscular dysfunction in snake envenoming. We reviewed the clinical and experimental evidence-base for the efficacy and effectiveness of antivenom in snakebite neurotoxicity. The main site of snake neurotoxins is the neuromuscular junction, and the
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Antivenom therapy is currently the standard practice for treating neuromuscular dysfunction in snake envenoming. We reviewed the clinical and experimental evidence-base for the efficacy and effectiveness of antivenom in snakebite neurotoxicity. The main site of snake neurotoxins is the neuromuscular junction, and the majority are either: (1) pre-synaptic neurotoxins irreversibly damaging the presynaptic terminal; or (2) post-synaptic neurotoxins that bind to the nicotinic acetylcholine receptor. Pre-clinical tests of antivenom efficacy for neurotoxicity include rodent lethality tests, which are problematic, and in vitro pharmacological tests such as nerve-muscle preparation studies, that appear to provide more clinically meaningful information. We searched MEDLINE (from 1946) and EMBASE (from 1947) until March 2017 for clinical studies. The search yielded no randomised placebo-controlled trials of antivenom for neuromuscular dysfunction. There were several randomised and non-randomised comparative trials that compared two or more doses of the same or different antivenom, and numerous cohort studies and case reports. The majority of studies available had deficiencies including poor case definition, poor study design, small sample size or no objective measures of paralysis. A number of studies demonstrated the efficacy of antivenom in human envenoming by clearing circulating venom. Studies of snakes with primarily pre-synaptic neurotoxins, such as kraits (Bungarus spp.) and taipans (Oxyuranus spp.) suggest that antivenom does not reverse established neurotoxicity, but early administration may be associated with decreased severity or prevent neurotoxicity. Small studies of snakes with mainly post-synaptic neurotoxins, including some cobra species (Naja spp.), provide preliminary evidence that neurotoxicity may be reversed with antivenom, but placebo controlled studies with objective outcome measures are required to confirm this. Full article
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Open AccessComment
Comment on Indoxyl Sulfate—Review of Toxicity and Therapeutic Strategies. Toxins 2016, 8, 358
Toxins 2017, 9(4), 142; doi:10.3390/toxins9040142 -
Abstract
Recently, the clinical and experimental evidences that support the toxic effects of indoxyl sulfate, a protein-bound uremic toxin in chronic kidney disease (CKD) patients, has been discussed. In this panorama, the authors described several in vitro and in vivo studies, suggesting that indoxyl
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Recently, the clinical and experimental evidences that support the toxic effects of indoxyl sulfate, a protein-bound uremic toxin in chronic kidney disease (CKD) patients, has been discussed. In this panorama, the authors described several in vitro and in vivo studies, suggesting that indoxyl sulfate may play a part in the pathogenesis of low turnover bone disease. However, the discussion claims the need for relevant clinical studies in CKD patients whose bone turnover biomarkers and bone histomorphometry were assessed in order to demonstrate the association between serum levels of indoxyl sulfate and bone turnover. We would like to underline the availability of this clinical data to support the concept that indoxyl sulfate may play a part in the pathogenesis of low turnover bone disease in CKD patients. Full article
Open AccessArticle
Modification of the Mycotoxin Deoxynivalenol Using Microorganisms Isolated from Environmental Samples
Toxins 2017, 9(4), 141; doi:10.3390/toxins9040141 -
Abstract
The trichothecene mycotoxin deoxynivalenol (DON) is a common contaminant of wheat, barley, and maize. New strategies are needed to reduce or eliminate DON in feed and food products. Microorganisms from plant and soil samples collected in Blacksburg, VA, USA, were screened by incubation
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The trichothecene mycotoxin deoxynivalenol (DON) is a common contaminant of wheat, barley, and maize. New strategies are needed to reduce or eliminate DON in feed and food products. Microorganisms from plant and soil samples collected in Blacksburg, VA, USA, were screened by incubation in a mineral salt media containing 100 μg/mL DON and analysis by gas chromatography mass spectrometry (GC/MS). Two mixed cultures derived from soil samples consistently decreased DON levels in assays using DON as the sole carbon source. Nuclear magnetic resonance (NMR) analysis indicated that 3-keto-4-deoxynivalenol was the major by-product of DON. Via 16S rRNA sequencing, these mixed cultures, including mostly members of the genera Acinetobacter, Leadbetterella, and Gemmata, were revealed. Incubation of one of these mixed cultures with wheat samples naturally contaminated with 7.1 μg/mL DON indicated nearly complete conversion of DON to the less toxic 3-epimer-DON (3-epi-DON). Our work extends previous studies that have demonstrated the potential for bioprospecting for microorganisms from the environment to remediate or modify mycotoxins for commercial applications, such as the reduction of mycotoxins in fuel ethanol co-products. Full article
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Open AccessReview
Toxins of Prokaryotic Toxin-Antitoxin Systems with Sequence-Specific Endoribonuclease Activity
Toxins 2017, 9(4), 140; doi:10.3390/toxins9040140 -
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
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Open AccessReview
Sequence Polymorphism and Intrinsic Structural Disorder as Related to Pathobiological Performance of the Helicobacter pylori CagA Oncoprotein
Toxins 2017, 9(4), 136; doi:10.3390/toxins9040136 -
Abstract
CagA, an oncogenic virulence factor produced by Helicobacter pylori, is causally associated with the development of gastrointestinal diseases such as chronic gastritis, peptic ulcers, and gastric cancer. Upon delivery into gastric epithelial cells via bacterial type IV secretion, CagA interacts with a
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CagA, an oncogenic virulence factor produced by Helicobacter pylori, is causally associated with the development of gastrointestinal diseases such as chronic gastritis, peptic ulcers, and gastric cancer. Upon delivery into gastric epithelial cells via bacterial type IV secretion, CagA interacts with a number of host proteins through the intrinsically disordered C-terminal tail, which contains two repeatable protein-binding motifs, the Glu-Pro-Ile-Tyr-Ala (EPIYA) motif and the CagA multimerization (CM) motif. The EPIYA motif, upon phosphorylation by host kinases, binds and deregulates Src homology 2 domain-containing protein tyrosine phosphatase 2 (SHP2), a bona fide oncoprotein, inducing pro-oncogenic mitogenic signaling and abnormal cell morphology. Through the CM motif, CagA inhibits the kinase activity of polarity regulator partitioning-defective 1b (PAR1b), causing junctional and polarity defects while inducing actin cytoskeletal rearrangements. The magnitude of the pathobiological action of individual CagA has been linked to the tandem repeat polymorphisms of these two binding motifs, yet the molecular mechanisms by which they affect disease outcome remain unclear. Recent studies using quantitative techniques have provided new insights into how the sequence polymorphisms in the structurally disordered C-terminal region determine the degree of pro-oncogenic action of CagA in the gastric epithelium. Full article
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Open AccessArticle
Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria
Toxins 2017, 9(4), 139; doi:10.3390/toxins9040139 -
Abstract
This work represents the first initiative to analyze the distribution of B. thuringiensis in Algeria and to evaluate the biological potential of the isolates. A total of 157 isolates were recovered, with at least one isolate in 94.4% of the samples. The highest
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This work represents the first initiative to analyze the distribution of B. thuringiensis in Algeria and to evaluate the biological potential of the isolates. A total of 157 isolates were recovered, with at least one isolate in 94.4% of the samples. The highest Bt index was found in samples from rhizospheric soil (0.48) and from the Mediterranean area (0.44). Most isolates showed antifungal activity (98.5%), in contrast to the few that had antibacterial activity (29.9%). A high genetic diversity was made evident by the finding of many different crystal shapes and various combinations of shapes within a single isolate (in 58.4% of the isolates). Also, over 50% of the isolates harbored cry1, cry2, or cry9 genes, and 69.3% contained a vip3 gene. A good correlation between the presence of chitinase genes and antifungal activity was observed. More than half of the isolates with a broad spectrum of antifungal activity harbored both endochitinase and exochitinase genes. Interestingly, 15 isolates contained the two chitinase genes and all of the above cry family genes, with some of them harboring a vip3 gene as well. The combination of this large number of genes coding for entomopathogenic proteins suggests a putative wide range of entomotoxic activity. Full article
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Open AccessArticle
An On-Site, Ultra-Sensitive, Quantitative Sensing Method for the Determination of Total Aflatoxin in Peanut and Rice Based on Quantum Dot Nanobeads Strip
Toxins 2017, 9(4), 137; doi:10.3390/toxins9040137 -
Abstract
An on-site, ultra-sensitive, and quantitative sensing method was developed based on quantum dot nanobeads (QDNBs) and a test strip for the determination of total aflatoxins (AFTs) in rice and peanuts. The monoclonal antibody against AFT (mAbAFT) was homemade and labeled with
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An on-site, ultra-sensitive, and quantitative sensing method was developed based on quantum dot nanobeads (QDNBs) and a test strip for the determination of total aflatoxins (AFTs) in rice and peanuts. The monoclonal antibody against AFT (mAbAFT) was homemade and labeled with QDNB. After the pre-coating of the AFT antigen on the test line (T line), the competitive immunoreactions were conducted between AFT and AFT antigen on the T line with QDNBs-mAbAFT. Under optimal conditions, this approach allowed a rapid response towards AFT with a considerable sensitivity of 1.4 pg/mL and 2.9 pg/mL in rice and peanut matrices, respectively. The put-in and put-out durations were within 10 min. The recoveries for AFT in rice and peanut sample matrices were recorded from 86.25% to 118.0%, with relative deviations (RSD) below 12%. The assay was further validated via the comparison between this QDNB strip and the conventional HPLC method using spiked samples. Thus, the design provided a potential alternative for on-site, ultra-sensitive, and quantitative sensing of AFT that could also be expanded to other chemical contaminants for food safety. Full article
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Open AccessArticle
Suppression of Hepatic Epithelial-to-Mesenchymal Transition by Melittin via Blocking of TGFβ/Smad and MAPK-JNK Signaling Pathways
Toxins 2017, 9(4), 138; doi:10.3390/toxins9040138 -
Abstract
Transforming growth factor (TGF)-β1 plays a crucial role in the epithelial-to-mesenchymal transition (EMT) in hepatocytes and hepatic stellate cells (HSC), which contributes to the pathogenesis of liver fibrosis. Melittin (MEL) is a major component of bee venom and is effective in rheumatoid arthritis,
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Transforming growth factor (TGF)-β1 plays a crucial role in the epithelial-to-mesenchymal transition (EMT) in hepatocytes and hepatic stellate cells (HSC), which contributes to the pathogenesis of liver fibrosis. Melittin (MEL) is a major component of bee venom and is effective in rheumatoid arthritis, pain relief, cancer cell proliferation, fibrosis and immune modulating activity. In this study, we found that MEL inhibits hepatic EMT in vitro and in vivo, regulating the TGFβ/Smad and TGFβ/nonSmad signaling pathways. MEL significantly inhibited TGF-β1-induced expression of EMT markers (E-cadherin reduction and vimentin induction) in vitro. These results were confirmed in CCl4-induced liver in vivo. Treatment with MEL almost completely blocked the phosphorylation of Smad2/3, translocation of Smad4 and phosphorylation of JNK in vitro and in vivo. Taken together, these results suggest that MEL suppresses EMT by inhibiting the TGFβ/Smad and TGFβ/nonSmad-c-Jun N-terminal kinase (JNK)/Mitogen-activated protein kinase (MAPK) signaling pathways. These results indicated that MEL possesses potent anti-fibrotic and anti-EMT properties, which may be responsible for its effects on liver diseases. Full article
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Open AccessArticle
Protein Discovery: Combined Transcriptomic and Proteomic Analyses of Venom from the Endoparasitoid Cotesia chilonis (Hymenoptera: Braconidae)
Toxins 2017, 9(4), 135; doi:10.3390/toxins9040135 -
Abstract
Many species of endoparasitoid wasps provide biological control services in agroecosystems. Although there is a great deal of information on the ecology and physiology of host/parasitoid interactions, relatively little is known about the protein composition of venom and how specific venom proteins influence
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Many species of endoparasitoid wasps provide biological control services in agroecosystems. Although there is a great deal of information on the ecology and physiology of host/parasitoid interactions, relatively little is known about the protein composition of venom and how specific venom proteins influence physiological systems within host insects. This is a crucial gap in our knowledge because venom proteins act in modulating host physiology in ways that favor parasitoid development. Here, we identified 37 possible venom proteins from the polydnavirus-carrying endoparasitoid Cotesia chilonis by combining transcriptomic and proteomic analyses. The most abundant proteins were hydrolases, such as proteases, peptidases, esterases, glycosyl hydrolase, and endonucleases. Some components are classical parasitoid venom proteins with known functions, including extracellular superoxide dismutase 3, serine protease inhibitor and calreticulin. The venom contains novel proteins, not recorded from any other parasitoid species, including tolloid-like proteins, chitooligosaccharidolytic β-N-acetylglucosaminidase, FK506-binding protein 14, corticotropin-releasing factor-binding protein and vascular endothelial growth factor receptor 2. These new data generate hypotheses and provide a platform for functional analysis of venom components. Full article
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Open AccessArticle
Differences in Ribosome Binding and Sarcin/Ricin Loop Depurination by Shiga and Ricin Holotoxins
Toxins 2017, 9(4), 133; doi:10.3390/toxins9040133 -
Abstract
Both ricin and Shiga holotoxins display no ribosomal activity in their native forms and need to be activated to inhibit translation in a cell-free translation inhibition assay. This is because the ribosome binding site of the ricin A chain (RTA) is blocked by
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Both ricin and Shiga holotoxins display no ribosomal activity in their native forms and need to be activated to inhibit translation in a cell-free translation inhibition assay. This is because the ribosome binding site of the ricin A chain (RTA) is blocked by the B subunit in ricin holotoxin. However, it is not clear why Shiga toxin 1 (Stx1) or Shiga toxin 2 (Stx2) holotoxin is not active in a cell-free system. Here, we compare the ribosome binding and depurination activity of Stx1 and Stx2 holotoxins with the A1 subunits of Stx1 and Stx2 using either the ribosome or a 10-mer RNA mimic of the sarcin/ricin loop as substrates. Our results demonstrate that the active sites of Stx1 and Stx2 holotoxins are blocked by the A2 chain and the B subunit, while the ribosome binding sites are exposed to the solvent. Unlike ricin, which is enzymatically active, but cannot interact with the ribosome, Stx1 and Stx2 holotoxins are enzymatically inactive but can interact with the ribosome. Full article
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Open AccessReview
Proteolysis in Helicobacter pylori-Induced Gastric Cancer
Toxins 2017, 9(4), 134; doi:10.3390/toxins9040134 -
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
[...] Read more.
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
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Open AccessReview
Helicobacter pylori Strains and Gastric MALT Lymphoma
Toxins 2017, 9(4), 132; doi:10.3390/toxins9040132 -
Abstract
This article summarizes the main findings concerning Helicobacter pylori associated with gastric MALT lymphoma (GML). Considered together, GML strains based on their virulence factor profile appear to be less virulent than those associated with peptic ulcers or gastric adenocarcinoma. A particular Lewis antigen
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This article summarizes the main findings concerning Helicobacter pylori associated with gastric MALT lymphoma (GML). Considered together, GML strains based on their virulence factor profile appear to be less virulent than those associated with peptic ulcers or gastric adenocarcinoma. A particular Lewis antigen profile has been identified in GML strains and could represent an alternative adaptive mechanism to escape the host immune response thereby allowing continuous antigenic stimulation of infiltrating lymphocytes. Full article
Open AccessReview
Strategies and Methodologies for Developing Microbial Detoxification Systems to Mitigate Mycotoxins
Toxins 2017, 9(4), 130; doi:10.3390/toxins9040130 -
Abstract
Mycotoxins, the secondary metabolites of mycotoxigenic fungi, have been found in almost all agricultural commodities worldwide, causing enormous economic losses in livestock production and severe human health problems. Compared to traditional physical adsorption and chemical reactions, interest in biological detoxification methods that are
[...] Read more.
Mycotoxins, the secondary metabolites of mycotoxigenic fungi, have been found in almost all agricultural commodities worldwide, causing enormous economic losses in livestock production and severe human health problems. Compared to traditional physical adsorption and chemical reactions, interest in biological detoxification methods that are environmentally sound, safe and highly efficient has seen a significant increase in recent years. However, researchers in this field have been facing tremendous unexpected challenges and are eager to find solutions. This review summarizes and assesses the research strategies and methodologies in each phase of the development of microbiological solutions for mycotoxin mitigation. These include screening of functional microbial consortia from natural samples, isolation and identification of single colonies with biotransformation activity, investigation of the physiological characteristics of isolated strains, identification and assessment of the toxicities of biotransformation products, purification of functional enzymes and the application of mycotoxin decontamination to feed/food production. A full understanding and appropriate application of this tool box should be helpful towards the development of novel microbiological solutions on mycotoxin detoxification. Full article
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Open AccessFeature PaperArticle
Insights into the Structure of the Vip3Aa Insecticidal Protein by Protease Digestion Analysis
Toxins 2017, 9(4), 131; doi:10.3390/toxins9040131 -
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
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