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Toxins, Volume 8, Issue 11 (November 2016)

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Cover Story (view full-size image) C. perfringens type D strain CN3718 attachment to Caco-2 cells. C. perfringens CN3718 produces [...] Read more.
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Open AccessArticle Integrating scFv into xMAP Assays for the Detection of Marine Toxins
Toxins 2016, 8(11), 346; https://doi.org/10.3390/toxins8110346
Received: 21 September 2016 / Revised: 9 November 2016 / Accepted: 16 November 2016 / Published: 21 November 2016
Cited by 2 | Viewed by 1494 | PDF Full-text (2817 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Marine toxins, such as saxitoxin and domoic acid are associated with algae blooms and can bioaccumulate in shell fish which present both health and economic concerns. The ability to detect the presence of toxin is paramount for the administration of the correct supportive [...] Read more.
Marine toxins, such as saxitoxin and domoic acid are associated with algae blooms and can bioaccumulate in shell fish which present both health and economic concerns. The ability to detect the presence of toxin is paramount for the administration of the correct supportive care in case of intoxication; environmental monitoring to detect the presence of toxin is also important for prevention of intoxication. Immunoassays are one tool that has successfully been applied to the detection of marine toxins. Herein, we had the variable regions of two saxitoxin binding monoclonal antibodies sequenced and used the information to produce recombinant constructs that consist of linked heavy and light variable domains that make up the binding domains of the antibodies (scFv). Recombinantly produced binding elements such as scFv provide an alternative to traditional antibodies and serve to “preserve” monoclonal antibodies as they can be easily recreated from their sequence data. In this paper, we combined the anti-saxitoxin scFv developed here with a previously developed anti-domoic acid scFv and demonstrated their utility in a microsphere-based competitive immunoassay format. In addition to detection in buffer, we demonstrated equivalent sensitivity in oyster and scallop matrices. The potential for multiplexed detection using scFvs in this immunoassay format is demonstrated. Full article
(This article belongs to the collection Marine and Freshwater Toxins)
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Open AccessReview Recombinant Alpha, Beta, and Epsilon Toxins of Clostridium perfringens: Production Strategies and Applications as Veterinary Vaccines
Toxins 2016, 8(11), 340; https://doi.org/10.3390/toxins8110340
Received: 20 October 2016 / Revised: 10 November 2016 / Accepted: 14 November 2016 / Published: 21 November 2016
Cited by 6 | Viewed by 2558 | PDF Full-text (2635 KB) | HTML Full-text | XML Full-text
Abstract
Clostridium perfringens is a spore-forming, commensal, ubiquitous bacterium that is present in the gastrointestinal tract of healthy humans and animals. This bacterium produces up to 18 toxins. The species is classified into five toxinotypes (A–E) according to the toxins that the bacterium produces: [...] Read more.
Clostridium perfringens is a spore-forming, commensal, ubiquitous bacterium that is present in the gastrointestinal tract of healthy humans and animals. This bacterium produces up to 18 toxins. The species is classified into five toxinotypes (A–E) according to the toxins that the bacterium produces: alpha, beta, epsilon, or iota. Each of these toxinotypes is associated with myriad different, frequently fatal, illnesses that affect a range of farm animals and humans. Alpha, beta, and epsilon toxins are the main causes of disease. Vaccinations that generate neutralizing antibodies are the most common prophylactic measures that are currently in use. These vaccines consist of toxoids that are obtained from C. perfringens cultures. Recombinant vaccines offer several advantages over conventional toxoids, especially in terms of the production process. As such, they are steadily gaining ground as a promising vaccination solution. This review discusses the main strategies that are currently used to produce recombinant vaccines containing alpha, beta, and epsilon toxins of C. perfringens, as well as the potential application of these molecules as vaccines for mammalian livestock animals. Full article
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Open AccessArticle Effect of Fusarium-Derived Metabolites on the Barrier Integrity of Differentiated Intestinal Porcine Epithelial Cells (IPEC-J2)
Toxins 2016, 8(11), 345; https://doi.org/10.3390/toxins8110345
Received: 20 September 2016 / Revised: 20 October 2016 / Accepted: 15 November 2016 / Published: 19 November 2016
Cited by 8 | Viewed by 1553 | PDF Full-text (2176 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The human, animal and plant pathogen Fusarium, which contaminates agricultural commodities worldwide, produces numerous secondary metabolites. An example is the thoroughly-investigated deoxynivalenol (DON), which severely impairs gastrointestinal barrier integrity. However, to date, the toxicological profile of other Fusarium-derived metabolites, such as [...] Read more.
The human, animal and plant pathogen Fusarium, which contaminates agricultural commodities worldwide, produces numerous secondary metabolites. An example is the thoroughly-investigated deoxynivalenol (DON), which severely impairs gastrointestinal barrier integrity. However, to date, the toxicological profile of other Fusarium-derived metabolites, such as enniatins, beauvericin, moniliformin, apicidin, aurofusarin, rubrofusarin, equisetin and bikaverin, are poorly characterized. Thus we examined their effects—as metabolites alone and as metabolites in combination with DON—on the intestinal barrier function of differentiated intestinal porcine epithelial cells (IPEC-J2) over 72 h. Transepithelial electrical resistance (TEER) was measured at 24-h intervals, followed by evaluation of cell viability using neutral red (NR) assay. Enniatins A, A1, B and B1, apicidin, aurofusarin and beauvericin significantly reduced TEER. Moniliformin, equisetin, bikaverin and rubrofusarin had no effect on TEER. In the case of apicidin, aurofusarin and beauvericin, TEER reductions were further substantiated by the addition of otherwise no-effect DON concentrations. In all cases, viability was unaffected, confirming that TEER reductions were not due to compromised viability. Considering the prevalence of mycotoxin contamination and the diseases associated with intestinal barrier disruption, consumption of contaminated food or feed may have substantial health implications. Full article
(This article belongs to the Section Mycotoxins)
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Open AccessArticle Spotlight on the Underdogs—An Analysis of Underrepresented Alternaria Mycotoxins Formed Depending on Varying Substrate, Time and Temperature Conditions
Toxins 2016, 8(11), 344; https://doi.org/10.3390/toxins8110344
Received: 15 October 2016 / Revised: 11 November 2016 / Accepted: 13 November 2016 / Published: 19 November 2016
Cited by 9 | Viewed by 1631 | PDF Full-text (2999 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Alternaria (A.) is a genus of widespread fungi capable of producing numerous, possibly health-endangering Alternaria toxins (ATs), which are usually not the focus of attention. The formation of ATs depends on the species and complex interactions of various environmental factors and is not [...] Read more.
Alternaria (A.) is a genus of widespread fungi capable of producing numerous, possibly health-endangering Alternaria toxins (ATs), which are usually not the focus of attention. The formation of ATs depends on the species and complex interactions of various environmental factors and is not fully understood. In this study the influence of temperature (7 °C, 25 °C), substrate (rice, wheat kernels) and incubation time (4, 7, and 14 days) on the production of thirteen ATs and three sulfoconjugated ATs by three different Alternaria isolates from the species groups A. tenuissima and A. infectoria was determined. High-performance liquid chromatography coupled with tandem mass spectrometry was used for quantification. Under nearly all conditions, tenuazonic acid was the most extensively produced toxin. At 25 °C and with increasing incubation time all toxins were formed in high amounts by the two A. tenuissima strains on both substrates with comparable mycotoxin profiles. However, for some of the toxins, stagnation or a decrease in production was observed from day 7 to 14. As opposed to the A. tenuissima strains, the A. infectoria strain only produced low amounts of ATs, but high concentrations of stemphyltoxin III. The results provide an essential insight into the quantitative in vitro AT formation under different environmental conditions, potentially transferable to different field and storage conditions. Full article
(This article belongs to the Special Issue LC-MS/MS Method for Mycotoxin Analysis) Printed Edition available
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Open AccessReview Clostridium perfringens Sialidases: Potential Contributors to Intestinal Pathogenesis and Therapeutic Targets
Toxins 2016, 8(11), 341; https://doi.org/10.3390/toxins8110341
Received: 28 October 2016 / Revised: 10 November 2016 / Accepted: 13 November 2016 / Published: 19 November 2016
Cited by 7 | Viewed by 2664 | PDF Full-text (1671 KB) | HTML Full-text | XML Full-text
Abstract
Clostridium perfringens is a major cause of histotoxic and intestinal infections of humans and other animals. This Gram-positive anaerobic bacterium can produce up to three sialidases named NanH, NanI, and NanJ. The role of sialidases in histotoxic infections, such as gas gangrene (clostridial [...] Read more.
Clostridium perfringens is a major cause of histotoxic and intestinal infections of humans and other animals. This Gram-positive anaerobic bacterium can produce up to three sialidases named NanH, NanI, and NanJ. The role of sialidases in histotoxic infections, such as gas gangrene (clostridial myonecrosis), remains equivocal. However, recent in vitro studies suggest that NanI may contribute to intestinal virulence by upregulating production of some toxins associated with intestinal infection, increasing the binding and activity of some of those toxins, and enhancing adherence of C. perfringens to intestinal cells. Possible contributions of NanI to intestinal colonization are further supported by observations that the C. perfringens strains causing acute food poisoning in humans often lack the nanI gene, while other C. perfringens strains causing chronic intestinal infections in humans usually carry a nanI gene. Certain sialidase inhibitors have been shown to block NanI activity and reduce C. perfringens adherence to cultured enterocyte-like cells, opening the possibility that sialidase inhibitors could be useful therapeutics against C. perfringens intestinal infections. These initial in vitro observations should be tested for their in vivo significance using animal models of intestinal infections. Full article
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Open AccessArticle Mycotoxin Contamination in Sugarcane Grass and Juice: First Report on Detection of Multiple Mycotoxins and Exposure Assessment for Aflatoxins B1 and G1 in Humans
Toxins 2016, 8(11), 343; https://doi.org/10.3390/toxins8110343
Received: 10 September 2016 / Revised: 10 November 2016 / Accepted: 13 November 2016 / Published: 18 November 2016
Cited by 11 | Viewed by 1398 | PDF Full-text (255 KB) | HTML Full-text | XML Full-text
Abstract
This study was conducted to investigate the natural co-occurrence of multiple toxic fungal and bacterial metabolites in sugarcane grass and juice intended for human consumption in Upper Egypt. Quantification of the target analytes has been done using the “dilute and shoot” approach followed [...] Read more.
This study was conducted to investigate the natural co-occurrence of multiple toxic fungal and bacterial metabolites in sugarcane grass and juice intended for human consumption in Upper Egypt. Quantification of the target analytes has been done using the “dilute and shoot” approach followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total number of 29 and 33 different metabolites were detected in 21 sugarcane grass and 40 juice samples, respectively, with a trend of concentrations being higher in grass than in juice. Among the regulated mycotoxins, only aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1) were detected. The prevalence of AFB1 was in 48% of grass samples and in 58% of juice with a maximum concentration of 30.6 μg/kg and 2.10 μg/kg, respectively. AFG1 was detected in 10% of grass samples (7.76 μg/kg) and 18% of juice samples (34 μg/kg). Dietary exposure was assessed using a juice frequency questionnaire of adult inhabitants in Assiut City. The assessment revealed different levels of exposure to AFB1 between males and females in winter and summer seasons. The estimated seasonal exposure ranged from 0.20 to 0.40 ng/kg b.w./day in winter and from 0.38 to 0.90 ng/kg b.w./day in summer. Full article
Open AccessArticle Occurrence of Fusarium Mycotoxins in Cereal Crops and Processed Products (Ogi) from Nigeria
Toxins 2016, 8(11), 342; https://doi.org/10.3390/toxins8110342
Received: 30 September 2016 / Revised: 8 November 2016 / Accepted: 13 November 2016 / Published: 18 November 2016
Cited by 23 | Viewed by 2051 | PDF Full-text (1238 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In Nigeria, maize, sorghum, and millet are very important cash crops. They are consumed on a daily basis in different processed forms in diverse cultural backgrounds. These crops are prone to fungi infestation, and subsequently may be contaminated with mycotoxins. A total of [...] Read more.
In Nigeria, maize, sorghum, and millet are very important cash crops. They are consumed on a daily basis in different processed forms in diverse cultural backgrounds. These crops are prone to fungi infestation, and subsequently may be contaminated with mycotoxins. A total of 363 samples comprising of maize (136), sorghum (110), millet (87), and ogi (30) were collected from randomly selected markets in four agro-ecological zones in Nigeria. Samples were assessed for Fusarium mycotoxins contamination using a multi-mycotoxin liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Subsequently, some selected samples were analysed for the occurrence of hidden fumonisins. Overall, 64% of the samples were contaminated with at least one toxin, at the rate of 77%, 44%, 59%, and 97% for maize, sorghum, millet, and ogi, respectively. Fumonisins were the most dominant, especially in maize and ogi, occurring at the rate of 65% and 93% with mean values of 935 and 1128 μg/kg, respectively. The prevalence of diacetoxyscirpenol was observed in maize (13%), sorghum (18%), and millet (29%), irrespective of the agro-ecological zone. Other mycotoxins detected were deoxynivalenol, zearalenone, and their metabolites, nivalenol, fusarenon-X, HT-2 toxin, and hidden fumonisins. About 43% of the samples were contaminated with more than one toxin. This study suggests that consumption of cereals and cereal-based products, ogi particularly by infants may be a source of exposure to Fusarium mycotoxins. Full article
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Open AccessArticle Deoxynivalenol and Its Modified Forms: Are There Major Differences?
Toxins 2016, 8(11), 334; https://doi.org/10.3390/toxins8110334
Received: 4 July 2016 / Revised: 31 October 2016 / Accepted: 8 November 2016 / Published: 16 November 2016
Cited by 10 | Viewed by 1864 | PDF Full-text (3633 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Considering the diverse toxic effects of the Fusarium toxin deoxynivalenol (DON), its common occurrence in wheat-based products, and its stability during processing, DON constitutes an increasing health concern for humans and animals. In addition to the parent compound DON, human and animal exposure [...] Read more.
Considering the diverse toxic effects of the Fusarium toxin deoxynivalenol (DON), its common occurrence in wheat-based products, and its stability during processing, DON constitutes an increasing health concern for humans and animals. In addition to the parent compound DON, human and animal exposure encompasses the acetylated fungal metabolites 3-acetyl-deoxynivalenol (3ADON) and 15-acetyl-deoxynivalenol (15ADON) as well as the plant-derived DON-glucoside (DON3G) and the bacterial product de-epoxy-DON (DOM-1). In the current study we used the well-established Caco-2 cell model to compare the effects of these naturally occurring forms of DON on cell viability and markers of barrier integrity, as well as on the release of the pro-inflammatory chemokine chemokine CXC motif ligand (CXCL8). Results show that 3ADON is less potent in inducing adverse effects on barrier integrity when compared to DON, whereas 15ADON appears to be slightly more potent than DON. In contrast, DON3G and DOM-1 exerted no measurable adverse effects on the intestinal barrier. It was also demonstrated that galacto-oligosaccharides (GOS) are able to protect epithelial cells against DON and its acetylated forms, which suggests that GOS are beneficial food additives in the protection of vulnerable segments of the human population against adverse effects of DON and its derivatives. Full article
(This article belongs to the collection Fusarium Toxins – Relevance for Human and Animal Health)
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Open AccessReview N-methyl-2-pyridone-5-carboxamide (2PY)—Major Metabolite of Nicotinamide: An Update on an Old Uremic Toxin
Toxins 2016, 8(11), 339; https://doi.org/10.3390/toxins8110339
Received: 22 September 2016 / Revised: 7 November 2016 / Accepted: 7 November 2016 / Published: 15 November 2016
Cited by 12 | Viewed by 1626 | PDF Full-text (971 KB) | HTML Full-text | XML Full-text
Abstract
N-methyl-2-pyridone-5-carboxamide (2PY, a major metabolite of nicotinamide, NAM) was recently identified as a uremic toxin. Recent interventional trials using NAM to treat high levels of phosphorus in end-stage renal disease have highlighted new potential uremic toxicities of 2PY. In the context of [...] Read more.
N-methyl-2-pyridone-5-carboxamide (2PY, a major metabolite of nicotinamide, NAM) was recently identified as a uremic toxin. Recent interventional trials using NAM to treat high levels of phosphorus in end-stage renal disease have highlighted new potential uremic toxicities of 2PY. In the context of uremia, the accumulation of 2PY could be harmful—perhaps by inhibiting poly (ADP-ribose) polymerase-1 activity. Here, we review recently published data on 2PY’s metabolism and toxicological profile. Full article
(This article belongs to the Special Issue Novel Issues in Uremic Toxicity)
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Open AccessArticle Addition of Carbon to the Culture Medium Improves the Detection Efficiency of Aflatoxin Synthetic Fungi
Toxins 2016, 8(11), 338; https://doi.org/10.3390/toxins8110338
Received: 18 October 2016 / Accepted: 11 November 2016 / Published: 15 November 2016
Cited by 3 | Viewed by 1729 | PDF Full-text (4627 KB) | HTML Full-text | XML Full-text
Abstract
Aflatoxin (AF) is a harmful secondary metabolite that is synthesized by the Aspergillus species. Although AF detection techniques have been developed, techniques for detection of AF synthetic fungi are still required. Techniques such as plate culture methods are continually being modified for this [...] Read more.
Aflatoxin (AF) is a harmful secondary metabolite that is synthesized by the Aspergillus species. Although AF detection techniques have been developed, techniques for detection of AF synthetic fungi are still required. Techniques such as plate culture methods are continually being modified for this purpose. However, plate culture methods require refinement because they suffer from several issues. In this study, activated charcoal powder (carbon) was added to a culture medium containing cyclodextrin (CD) to enhance the contrast of fluorescence and improve the detection efficiency for AF synthetic fungi. Two culture media, potato dextrose agar and yeast extract sucrose agar, were investigated using both plate and liquid cultures. The final concentrations of CD and carbon in the media were 3 mg/mL and 0.3 mg/mL, respectively. Addition of carbon improved the visibility of fluorescence by attenuating approximately 30% of light scattering. Several fungi that could not be detected with only CD in the medium were detected with carbon addition. The carbon also facilitated fungal growth in the potato dextrose liquid medium. The results suggest that addition of carbon to media can enhance the observation of AF-derived fluorescence. Full article
(This article belongs to the Section Mycotoxins)
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Open AccessArticle Impact of Dendrimer Terminal Group Chemistry on Blockage of the Anthrax Toxin Channel: A Single Molecule Study
Toxins 2016, 8(11), 337; https://doi.org/10.3390/toxins8110337
Received: 18 October 2016 / Revised: 7 November 2016 / Accepted: 7 November 2016 / Published: 15 November 2016
Cited by 2 | Viewed by 1741 | PDF Full-text (3167 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Nearly all the cationic molecules tested so far have been shown to reversibly block K+ current through the cation-selective PA63 channels of anthrax toxin in a wide nM–mM range of effective concentrations. A significant increase in channel-blocking activity of the cationic [...] Read more.
Nearly all the cationic molecules tested so far have been shown to reversibly block K+ current through the cation-selective PA63 channels of anthrax toxin in a wide nM–mM range of effective concentrations. A significant increase in channel-blocking activity of the cationic compounds was achieved when multiple copies of positively charged ligands were covalently linked to multivalent scaffolds, such as cyclodextrins and dendrimers. Even though multivalent binding can be strong when the individual bonds are relatively weak, for drug discovery purposes we often strive to design multivalent compounds with high individual functional group affinity toward the respective binding site on a multivalent target. Keeping this requirement in mind, here we perform a single-channel/single-molecule study to investigate kinetic parameters of anthrax toxin PA63 channel blockage by second-generation (G2) poly(amido amine) (PAMAM) dendrimers functionalized with different surface ligands, including G2-NH2, G2-OH, G2-succinamate, and G2-COONa. We found that the previously reported difference in IC50 values of the G2-OH/PA63 and G2-NH2/PA63 binding was determined by both on- and off-rates of the reversible dendrimer/channel binding reaction. In 1 M KCl, we observed a decrease of about three folds in k o n and a decrease of only about ten times in t r e s with G2-OH compared to G2-NH2. At the same time for both blockers, k o n and t r e s increased dramatically with transmembrane voltage increase. PAMAM dendrimers functionalized with negatively charged succinamate, but not carboxyl surface groups, still had some residual activity in inhibiting the anthrax toxin channels. At 100 mV, the on-rate of the G2-succinamate binding was comparable with that of G2-OH but showed weaker voltage dependence when compared to G2-OH and G2-NH2. The residence time of G2-succinamate in the channel exhibited opposite voltage dependence compared to G2-OH and G2-NH2, increasing with the cis-negative voltage increase. We also describe kinetics of the PA63 ion current modulation by two different types of the “imperfect” PAMAM dendrimers, the mixed-surface G2 75% OH 25% NH2 dendrimer and G3-NH2 dendron. At low voltages, both “imperfect” dendrimers show similar rate constants but significantly weaker voltage sensitivity when compared with the intact G2-NH2 PAMAM dendrimer. Full article
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Open AccessArticle Comparison of In-Solution Biorecognition Properties of Aptamers against Ochratoxin A
Toxins 2016, 8(11), 336; https://doi.org/10.3390/toxins8110336
Received: 5 October 2016 / Revised: 2 November 2016 / Accepted: 8 November 2016 / Published: 15 November 2016
Cited by 7 | Viewed by 1803 | PDF Full-text (2371 KB) | HTML Full-text | XML Full-text
Abstract
Ochratoxin A (OTA) is a mycotoxin produced as a secondary metabolite by several species of Aspergillus and Penicillium and frequently found as a natural contaminant in a wide range of food commodities. Novel and robust biorecognition agents for detecting this molecule are required. [...] Read more.
Ochratoxin A (OTA) is a mycotoxin produced as a secondary metabolite by several species of Aspergillus and Penicillium and frequently found as a natural contaminant in a wide range of food commodities. Novel and robust biorecognition agents for detecting this molecule are required. Aptamers are artificial nucleic acid ligands able to bind with high affinity and specificity to a given target molecule. In the last few years, three separate research groups have selected aptamers for ochratoxin A. While each of these three families of aptamers have been incorporated into various methods for detecting OTA, it is unclear if each aptamer candidate is better suited for a particular application. Here, we perform the first head-to-head comparison of solution-based binding parameters for these groups of aptamers. Based on our results, we provide recommendations for the appropriate choice of aptamer for incorporation into solution-based biorecognition assays and applications. Full article
(This article belongs to the collection Biorecognition Assays for Mycotoxins)
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Open AccessArticle Detoxification of Deoxynivalenol via Glycosylation Represents Novel Insights on Antagonistic Activities of Trichoderma when Confronted with Fusarium graminearum
Toxins 2016, 8(11), 335; https://doi.org/10.3390/toxins8110335
Received: 22 September 2016 / Revised: 8 November 2016 / Accepted: 10 November 2016 / Published: 15 November 2016
Cited by 10 | Viewed by 2006 | PDF Full-text (4232 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Deoxynivalenol (DON) is a mycotoxin mainly produced by the Fusarium graminearum complex, which are important phytopathogens that can infect crops and lead to a serious disease called Fusarium head blight (FHB). As the most common B type trichothecene mycotoxin, DON has toxic effects [...] Read more.
Deoxynivalenol (DON) is a mycotoxin mainly produced by the Fusarium graminearum complex, which are important phytopathogens that can infect crops and lead to a serious disease called Fusarium head blight (FHB). As the most common B type trichothecene mycotoxin, DON has toxic effects on animals and humans, which poses a risk to food security. Thus, efforts have been devoted to control DON contamination in different ways. Management of DON production by Trichoderma strains as a biological control-based strategy has drawn great attention recently. In our study, eight selected Trichoderma strains were evaluated for their antagonistic activities on F. graminearum by dual culture on potato dextrose agar (PDA) medium. As potential antagonists, Trichoderma strains showed prominent inhibitory effects on mycelial growth and mycotoxin production of F. graminearum. In addition, the modified mycotoxin deoxynivalenol-3-glucoside (D3G), which was once regarded as a detoxification product of DON in plant defense, was detected when Trichoderma were confronted with F. graminearum. The occurrence of D3G in F. graminearum and Trichoderma interaction was reported for the first time, and these findings provide evidence that Trichoderma strains possess a self-protection mechanism as plants to detoxify DON into D3G when competing with F. graminearum. Full article
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Open AccessArticle Screening and Identification of Novel Ochratoxin A-Producing Fungi from Grapes
Toxins 2016, 8(11), 333; https://doi.org/10.3390/toxins8110333
Received: 27 September 2016 / Revised: 24 October 2016 / Accepted: 8 November 2016 / Published: 12 November 2016
Cited by 9 | Viewed by 1572 | PDF Full-text (1827 KB) | HTML Full-text | XML Full-text
Abstract
Ochratoxin A (OTA) contamination has been established as a world-wide problem. In this study, the strains with the ability of OTA production were screened by analyzing the green fluorescence of the isolates colonies from the grapes in Zhenjiang with 365 nm UV light [...] Read more.
Ochratoxin A (OTA) contamination has been established as a world-wide problem. In this study, the strains with the ability of OTA production were screened by analyzing the green fluorescence of the isolates colonies from the grapes in Zhenjiang with 365 nm UV light and confirmed by HPLC with fluorescent detection (HPLC-FLD). The results showed that seven isolates acquired the characteristic of the fluorescence, of which only five showed the ability of OTA production as confirmed by HPLC-FLD analysis. The five OTA-producing strains were identified based on comparative sequence analysis of three conserved genes (ITS, BenA and RPB2) of the strains, and they are Talaromyces rugulosus (O1 and Q3), Penicillium commune (V5-1), Penicillium rubens (MQ-5) and Aspergillus aculeatus (MB1-1). There are two Penicillium species of the five OTA-producing strains and our study is the first to report that P. rubens, T. rugulosus and A. aculeatus can produce OTA. This work would contribute to comprehensively understanding the fungi with an OTA-producing ability in grapes before harvest and then take effective measures to prevent OTA production. Full article
(This article belongs to the collection Ochratoxins-Collection)
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Open AccessArticle A Structure Identification and Toxicity Assessment of the Degradation Products of Aflatoxin B1 in Peanut Oil under UV Irradiation
Toxins 2016, 8(11), 332; https://doi.org/10.3390/toxins8110332
Received: 20 September 2016 / Revised: 8 November 2016 / Accepted: 9 November 2016 / Published: 12 November 2016
Cited by 18 | Viewed by 2893 | PDF Full-text (2329 KB) | HTML Full-text | XML Full-text
Abstract
Aflatoxins, a group of extremely hazardous compounds because of their genotoxicity and carcinogenicity to human and animals, are commonly found in many tropical and subtropical regions. Ultraviolet (UV) irradiation is proven to be an effective method to reduce or detoxify aflatoxins. However, the [...] Read more.
Aflatoxins, a group of extremely hazardous compounds because of their genotoxicity and carcinogenicity to human and animals, are commonly found in many tropical and subtropical regions. Ultraviolet (UV) irradiation is proven to be an effective method to reduce or detoxify aflatoxins. However, the degradation products of aflatoxins under UV irradiation and their safety or toxicity have not been clear in practical production such as edible oil industry. In this study, the degradation products of aflatoxin B1 (AFB1) in peanut oil were analyzed by Ultra Performance Liquid Chromatograph-Thermo Quadrupole Exactive Focus mass spectrometry/mass spectrometry (UPLC-TQEF-MS/MS). The high-resolution mass spectra reflected that two main products were formed after the modification of a double bond in the terminal furan ring and the fracture of the lactone ring, while the small molecules especially nitrogen-containing compound may have participated in the photochemical reaction. According to the above results, the possible photodegradation pathway of AFB1 in peanut oil is proposed. Moreover, the human embryo hepatocytes viability assay indicated that the cell toxicity of degradation products after UV irradiation was much lower than that of AFB1, which could be attributed to the breakage of toxicological sites. These findings can provide new information for metabolic pathways and the hazard assessment of AFB1 using UV detoxification. Full article
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Open AccessCommunication Depicting the Discrepancy between Tri Genotype and Chemotype on the Basis of Strain CBS 139514 from a Field Population of F. graminearum Sensu Stricto from Argentina
Toxins 2016, 8(11), 330; https://doi.org/10.3390/toxins8110330
Received: 14 October 2016 / Revised: 31 October 2016 / Accepted: 8 November 2016 / Published: 12 November 2016
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Abstract
Recent studies on a field population of F. graminearum sensu stricto from Argentina revealed an atypical panel of strains identified through PCR genotyping as 15ADON genotypes, but producing high levels of 3ADON. Based on representative strain CBS 139514, we asked if the discrepancy [...] Read more.
Recent studies on a field population of F. graminearum sensu stricto from Argentina revealed an atypical panel of strains identified through PCR genotyping as 15ADON genotypes, but producing high levels of 3ADON. Based on representative strain CBS 139514, we asked if the discrepancy between the trichothecene genotype and chemotype might result from an inter-chemotype recombination of the chemotype-determining genes. To answer this, we sequenced the complete core Tri gene cluster (around 30,200 bp) from this strain and compared its sequence to sequence data of typical type B trichothecene genotypes/chemotypes. Sequence alignment showed that CBS 139514 has an identical sequence within the entire core Tri cluster to the 15ADON genotype. The revealed discrepancy underlines the need for using both molecular and chemical methods for reliable characterization of toxigenic strains of Fusarium. Full article
(This article belongs to the Section Mycotoxins)
Open AccessArticle Glutathione-Conjugates of Deoxynivalenol in Naturally Contaminated Grain Are Primarily Linked via the Epoxide Group
Toxins 2016, 8(11), 329; https://doi.org/10.3390/toxins8110329
Received: 31 August 2016 / Revised: 2 October 2016 / Accepted: 7 November 2016 / Published: 11 November 2016
Cited by 9 | Viewed by 1589 | PDF Full-text (2375 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A glutathione (GSH) adduct of the mycotoxin 4-deoxynivalenol (DON), together with a range of related conjugates, has recently been tentatively identified by LC-MS of DON-treated wheat spikelets. In this study, we prepared samples of DON conjugated at the 10- and 13-positions with GSH, [...] Read more.
A glutathione (GSH) adduct of the mycotoxin 4-deoxynivalenol (DON), together with a range of related conjugates, has recently been tentatively identified by LC-MS of DON-treated wheat spikelets. In this study, we prepared samples of DON conjugated at the 10- and 13-positions with GSH, Cys, CysGly, γ-GluCys and N-acetylcysteine (NAC). The mixtures of conjugates were used as standards for LC-HRMS analysis of one of the DON-treated wheat spikelet samples, as well as 19 Norwegian grain samples of spring wheat and 16 grain samples of oats that were naturally-contaminated with DON at concentrations higher than 1 mg/kg. The artificially-contaminated wheat spikelets contained conjugates of GSH, CysGly and Cys coupled at the olefinic 10-position of DON, whereas the naturally-contaminated harvest-ripe grain samples contained GSH, CysGly, Cys, and NAC coupled mainly at the 13-position on the epoxy group. The identities of the conjugates were confirmed by LC-HRMS comparison with authentic standards, oxidation to the sulfoxides with hydrogen peroxide, and examination of product-ion spectra from LC-HRMS/MS analysis. No γ-GluCys adducts of DON were detected in any of the samples. The presence of 15-O-acetyl-DON was demonstrated for the first time in Norwegian grain. The results indicate that a small but significant proportion of DON is metabolized via the GSH-conjugation pathway in plants. To our knowledge, this is the first report of in vivo conjugation of trichothecenes via their epoxy group, which has generally been viewed as unreactive. Because conjugation at the 13-position of DON and other trichothecenes has been shown to be irreversible, this type of conjugate may prove useful as a biomarker of exposure to DON and other 12,13-epoxytrichothecenes. Full article
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Open AccessArticle Development and Validation of a LC-ESI-MS/MS Method for the Determination of Alternaria Toxins Alternariol, Alternariol Methyl-Ether and Tentoxin in Tomato and Tomato-Based Products
Toxins 2016, 8(11), 328; https://doi.org/10.3390/toxins8110328
Received: 29 September 2016 / Revised: 8 November 2016 / Accepted: 9 November 2016 / Published: 11 November 2016
Cited by 24 | Viewed by 2620 | PDF Full-text (2139 KB) | HTML Full-text | XML Full-text
Abstract
Alternaria species are capable of producing several secondary toxic metabolites in infected plants and in agricultural commodities, which play important roles in food safety. Alternaria alternata turn out to be the most frequent fungal species invading tomatoes. Alternariol (AOH), alternariol monomethyl ether (AME), [...] Read more.
Alternaria species are capable of producing several secondary toxic metabolites in infected plants and in agricultural commodities, which play important roles in food safety. Alternaria alternata turn out to be the most frequent fungal species invading tomatoes. Alternariol (AOH), alternariol monomethyl ether (AME), and tentoxin (TEN) are some of the main Alternaria mycotoxins that can be found as contaminants in food. In this work, an analytical method based on liquid chromatography (LC) tandem mass spectrometry (MS/MS) detection for the simultaneous quantification of AOH, AME, and TEN in tomato and tomato-based products was developed. Mycotoxin analysis was performed by dispersive liquid-liquid microextraction (DLLME) combined with LC-ESI-MS/MS. Careful optimization of the MS/MS parameters was performed with an LC/MS system with the ESI interface in the positive ion mode. Mycotoxins were efficiently extracted from sample extract into a droplet of chloroform (100 µL) by DLLME technique using acetonitrile as a disperser solvent. Method validation following the Commission Decision No. 2002/657/EC was carried out by using tomato juice as a blank matrix. Limits of detection and quantitation were, respectively, in the range 0.7 and 3.5 ng/g. Recovery rates were above 80%. Relative standard deviations of repeatability (RSDr) and intermediate reproducibility (RSDR) were ≤ 9% and ≤ 15%, respectively, at levels of 25 and 50 ng/g. Five out of 30 analyzed samples resulted positive to at least one Alternaria toxin investigated. AOH was the most common Alternaria toxin found, but at levels close to LOQ (average content: 3.75 ng/g). Full article
(This article belongs to the Special Issue LC-MS/MS Method for Mycotoxin Analysis) Printed Edition available
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Open AccessArticle Curcumin Prevents Aflatoxin B1 Hepatoxicity by Inhibition of Cytochrome P450 Isozymes in Chick Liver
Toxins 2016, 8(11), 327; https://doi.org/10.3390/toxins8110327
Received: 31 August 2016 / Revised: 4 November 2016 / Accepted: 7 November 2016 / Published: 10 November 2016
Cited by 20 | Viewed by 1694 | PDF Full-text (1134 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This study was designed to establish if Curcumin (CM) alleviates Aflatoxin B1 (AFB1)-induced hepatotoxic effects and to determine whether alteration of the expression of cytochrome P450 (CYP450) isozymes is involved in the regulation of these effects in chick liver. One-day-old [...] Read more.
This study was designed to establish if Curcumin (CM) alleviates Aflatoxin B1 (AFB1)-induced hepatotoxic effects and to determine whether alteration of the expression of cytochrome P450 (CYP450) isozymes is involved in the regulation of these effects in chick liver. One-day-old male broilers (n = 120) were divided into four groups and used in a two by two factorial trial in which the main factors included supplementing AFB1 (< 5 vs. 100 μg/kg) and CM (0 vs. 150 mg/kg) in a corn/soybean-based diet. Administration of AFB1 induced liver injury, significantly decreasing albumin and total protein concentrations and increasing alanine aminotransferase and aspartate aminotransferase activities in serum, and induced hepatic histological lesions at week 2. AFB1 also significantly decreased hepatic glutathione peroxidase, catalase, and glutathione levels, while increasing malondialdehyde, 8-hydroxydeoxyguanosine, and exo-AFB1-8,9-epoxide (AFBO)-DNA concentrations. In addition, the mRNA and/or activity of enzymes responsible for the bioactivation of AFB1 into AFBO—including CYP1A1, CYP1A2, CYP2A6, and CYP3A4—were significantly induced in liver microsomes after 2-week exposure to AFB1. These alterations induced by AFB1 were prevented by CM supplementation. Conclusively, dietary CM protected chicks from AFB1-induced liver injury, potentially through the synergistic actions of increased antioxidant capacities and inhibition of the pivotal CYP450 isozyme-mediated activation of AFB1 to toxic AFBO. Full article
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Open AccessArticle Towards Engineering Novel PE-Based Immunotoxins by Targeting Them to the Nucleus
Toxins 2016, 8(11), 321; https://doi.org/10.3390/toxins8110321
Received: 19 July 2016 / Revised: 1 November 2016 / Accepted: 2 November 2016 / Published: 10 November 2016
Cited by 5 | Viewed by 2080 | PDF Full-text (4651 KB) | HTML Full-text | XML Full-text
Abstract
Exotoxin A (PE) from Pseudomonas aeruginosa is a bacterial ADP-ribosyltransferase, which can permanently inhibit translation in the attacked cells. Consequently, this toxin is frequently used in immunotoxins for targeted cancer therapies. In this study, we propose a novel modification to PE by incorporating [...] Read more.
Exotoxin A (PE) from Pseudomonas aeruginosa is a bacterial ADP-ribosyltransferase, which can permanently inhibit translation in the attacked cells. Consequently, this toxin is frequently used in immunotoxins for targeted cancer therapies. In this study, we propose a novel modification to PE by incorporating the NLS sequence at its C-terminus, to make it a selective agent against fast-proliferating cancer cells, as a nucleus-accumulated toxin should be separated from its natural substrate (eEF2) in slowly dividing cells. Here, we report the cytotoxic activity and selected biochemical properties of newly designed PE mutein using two cellular models: A549 and HepG2. We also present a newly developed protocol for efficient purification of recombinant PE and its muteins with very high purity and activity. We found that furin cleavage is not critical for the activity of PE in the analyzed cell lines. Surprisingly, we observed increased toxicity of the toxin accumulated in the nucleus. This might be explained by unexpected nuclease activity of PE and its potential ability to cleave chromosomal DNA, which seems to be a putative alternative intoxication mechanism. Further experimental investigations should address this newly detected activity to identify catalytic residues and elucidate the molecular mechanism responsible for this action. Full article
(This article belongs to the collection Immunotoxins 2016)
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Open AccessReview Trimethylamine N-Oxide: The Good, the Bad and the Unknown
Toxins 2016, 8(11), 326; https://doi.org/10.3390/toxins8110326
Received: 30 September 2016 / Revised: 31 October 2016 / Accepted: 3 November 2016 / Published: 8 November 2016
Cited by 60 | Viewed by 4758 | PDF Full-text (723 KB) | HTML Full-text | XML Full-text
Abstract
Trimethylamine N-oxide (TMAO) is a small colorless amine oxide generated from choline, betaine, and carnitine by gut microbial metabolism. It accumulates in the tissue of marine animals in high concentrations and protects against the protein-destabilizing effects of urea. Plasma level of TMAO [...] Read more.
Trimethylamine N-oxide (TMAO) is a small colorless amine oxide generated from choline, betaine, and carnitine by gut microbial metabolism. It accumulates in the tissue of marine animals in high concentrations and protects against the protein-destabilizing effects of urea. Plasma level of TMAO is determined by a number of factors including diet, gut microbial flora and liver flavin monooxygenase activity. In humans, a positive correlation between elevated plasma levels of TMAO and an increased risk for major adverse cardiovascular events and death is reported. The atherogenic effect of TMAO is attributed to alterations in cholesterol and bile acid metabolism, activation of inflammatory pathways and promotion foam cell formation. TMAO levels increase with decreasing levels of kidney function and is associated with mortality in patients with chronic kidney disease. A number of therapeutic strategies are being explored to reduce TMAO levels, including use of oral broad spectrum antibiotics, promoting the growth of bacteria that utilize TMAO as substrate and the development of target-specific molecules with varying level of success. Despite the accumulating evidence, it is questioned whether TMAO is the mediator of a bystander in the disease process. Thus, it is important to undertake studies examining the cellular signaling in physiology and pathological states in order to establish the role of TMAO in health and disease in humans. Full article
(This article belongs to the Special Issue Novel Issues in Uremic Toxicity)
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Open AccessReply Reply to Comment on Detection of Mycotoxin in Patients with Chronic Fatigue Syndrome. Toxins 2013, 5, 605-617” by Mark J. Mendell
Toxins 2016, 8(11), 325; https://doi.org/10.3390/toxins8110325
Received: 10 October 2016 / Accepted: 10 October 2016 / Published: 7 November 2016
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Abstract
The authors of [1] have received further correspondence from Mark J. Mendell [2] concerning the above paper.[...] Full article
(This article belongs to the Section Mycotoxins)
Open AccessComment Comment on Detection of Mycotoxins in Patients with Chronic Fatigue Syndrome Toxins 2013, 5, 605–617
Toxins 2016, 8(11), 324; https://doi.org/10.3390/toxins8110324
Received: 10 October 2016 / Accepted: 10 October 2016 / Published: 7 November 2016
Cited by 1 | Viewed by 935 | PDF Full-text (174 KB) | HTML Full-text | XML Full-text
Abstract
The paper by Brewer et al. (2013) has a key methodologic flaw [1].[...] Full article
(This article belongs to the Section Mycotoxins)
Open AccessReply Reply to Comment on Detection of Mycotoxins in Patients with Chronic Fatigue Syndrome Toxins 2013, 5, 605–617 by John W. Osterman, M.D.
Toxins 2016, 8(11), 323; https://doi.org/10.3390/toxins8110323
Received: 27 May 2016 / Accepted: 10 October 2016 / Published: 7 November 2016
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Abstract
This paper [1] was an observational case study.[...] Full article
(This article belongs to the Section Mycotoxins)
Open AccessComment Comment on Detection of Mycotoxins in Patients with Chronic Fatigue Syndrome. Toxins 2013, 5, 605–617
Toxins 2016, 8(11), 322; https://doi.org/10.3390/toxins8110322
Received: 18 May 2016 / Accepted: 10 October 2016 / Published: 7 November 2016
Cited by 2 | Viewed by 1143 | PDF Full-text (169 KB) | HTML Full-text | XML Full-text
Abstract
The paper by Brewer et al. entitled “Detection of Mycotoxins in Patients with Chronic Fatigue Syndrome.[...] Full article
(This article belongs to the Section Mycotoxins)
Open AccessArticle Screening of Cytotoxic B. cereus on Differentiated Caco-2 Cells and in Co-Culture with Mucus-Secreting (HT29-MTX) Cells
Toxins 2016, 8(11), 320; https://doi.org/10.3390/toxins8110320
Received: 1 August 2016 / Revised: 9 October 2016 / Accepted: 31 October 2016 / Published: 5 November 2016
Cited by 2 | Viewed by 1711 | PDF Full-text (1351 KB) | HTML Full-text | XML Full-text
Abstract
B. cereus is an opportunistic foodborne pathogen able to cause diarrhoea. However, the diarrhoeal potential of a B. cereus strain remains difficult to predict, because no simple correlation has yet been identified between the symptoms and a unique or a specific combination of [...] Read more.
B. cereus is an opportunistic foodborne pathogen able to cause diarrhoea. However, the diarrhoeal potential of a B. cereus strain remains difficult to predict, because no simple correlation has yet been identified between the symptoms and a unique or a specific combination of virulence factors. In this study, 70 B. cereus strains with different origins (food poisonings, foods and environment) have been selected to assess their enterotoxicity. The B. cereus cell-free supernatants have been tested for their toxicity in vitro, on differentiated (21 day-old) Caco-2 cells, using their ATP content, LDH release and NR accumulation. The genetic determinants of the main potential enterotoxins and virulence factors (ces, cytK, entFM, entS, hbl, nhe, nprA, piplC and sph) have also been screened by PCR. This analysis showed that none of these genes was able to fully explain the enterotoxicity of B. cereus strains. Additionally, in order to assess a possible effect of the mucus layer in vitro, a cytotoxicity comparison between a monoculture (Caco-2 cells) and a co-culture (Caco-2 and HT29-MTX mucus-secreting cells) model has been performed with selected B. cereus supernatants. It appeared that, in these conditions, the mucus layer had no notable influence on the cytotoxicity of B. cereus supernatants. Full article
(This article belongs to the Section Bacterial Toxins)
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Open AccessArticle Tenuifolide B from Cinnamomum tenuifolium Stem Selectively Inhibits Proliferation of Oral Cancer Cells via Apoptosis, ROS Generation, Mitochondrial Depolarization, and DNA Damage
Toxins 2016, 8(11), 319; https://doi.org/10.3390/toxins8110319
Received: 15 January 2016 / Revised: 11 October 2016 / Accepted: 19 October 2016 / Published: 5 November 2016
Cited by 9 | Viewed by 2111 | PDF Full-text (3656 KB) | HTML Full-text | XML Full-text
Abstract
The development of drugs that selectively kill oral cancer cells but are less harmful to normal cells still provide several challenges. In this study, the antioral cancer effects of tenuifolide B (TFB), extracted from the stem of the plant Cinnamomum tenuifolium are evaluated [...] Read more.
The development of drugs that selectively kill oral cancer cells but are less harmful to normal cells still provide several challenges. In this study, the antioral cancer effects of tenuifolide B (TFB), extracted from the stem of the plant Cinnamomum tenuifolium are evaluated in terms of their effects on cancer cell viability, cell cycle analysis, apoptosis, oxidative stress, and DNA damage. Cell viability of oral cancer cells (Ca9-22 and CAL 27) was found to be significantly inhibited by TFB in a dose-responsive manner in terms of ATP assay, yielding IC50 = 4.67 and 7.05 μM (24 h), but are less lethal to normal oral cells (HGF-1). Dose-responsive increases in subG1 populations as well as the intensities of flow cytometry-based annexin V/propidium iodide (PI) analysis and pancaspase activity suggested that apoptosis was inducible by TFB in these two types of oral cancer cells. Pretreatment with the apoptosis inhibitor (Z-VAD-FMK) reduced the annexin V intensity of these two TFB-treated oral cancer cells, suggesting that TFB induced apoptosis-mediated cell death to oral cancer cells. Cleaved-poly (ADP-ribose) polymerase (PARP) and cleaved-caspases 3, 8, and 9 were upregulated in these two TFB-treated oral cancer cells over time but less harmful for normal oral HGF-1 cells. Dose-responsive and time-dependent increases in reactive oxygen species (ROS) and decreases in mitochondrial membrane potential (MitoMP) in these two TFB-treated oral cancer cells suggest that TFB may generate oxidative stress as measured by flow cytometry. N-acetylcysteine (NAC) pretreatment reduced the TFB-induced ROS generation and further validated that ROS was relevant to TFB-induced cell death. Both flow cytometry and Western blotting demonstrated that the DNA double strand marker γH2AX dose-responsively increased in TFB-treated Ca9-22 cells and time-dependently increased in two TFB-treated oral cancer cells. Taken together, we infer that TFB can selectively inhibit cell proliferation of oral cancer cells through apoptosis, ROS generation, mitochondrial membrane depolarization, and DNA damage. Full article
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Open AccessArticle Pueraria mirifica Exerts Estrogenic Effects in the Mammary Gland and Uterus and Promotes Mammary Carcinogenesis in Donryu Rats
Toxins 2016, 8(11), 275; https://doi.org/10.3390/toxins8110275
Received: 3 June 2016 / Accepted: 13 September 2016 / Published: 4 November 2016
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Abstract
Pueraria mirifica (PM), a plant whose dried and powdered tuberous roots are now widely used in rejuvenating preparations to promote youthfulness in both men and women, may have major estrogenic influence. In this study, we investigated modifying effects of PM at various doses [...] Read more.
Pueraria mirifica (PM), a plant whose dried and powdered tuberous roots are now widely used in rejuvenating preparations to promote youthfulness in both men and women, may have major estrogenic influence. In this study, we investigated modifying effects of PM at various doses on mammary and endometrial carcinogenesis in female Donryu rats. Firstly, PM administered to ovariectomized animals at doses of 0.03%, 0.3%, and 3% in a phytoestrogen-low diet for 2 weeks caused significant increase in uterus weight. Secondly, a 4 week PM application to non-operated rats at a dose of 3% after 7,12-dimethylbenz[a]anthracene (DMBA) initiation resulted in significant elevation of cell proliferation in the mammary glands. In a third experiment, postpubertal administration of 0.3% (200 mg/kg body weight (b.w.)/day) PM to 5-week-old non-operated animals for 36 weeks following initiation of mammary and endometrial carcinogenesis with DMBA and N-ethyl-N′-nitro-N-nitrosoguanidine (ENNG), respectively, resulted in significant increase of mammary adenocarcinoma incidence. A significant increase of endometrial atypical hyperplasia multiplicity was also observed. Furthermore, PM at doses of 0.3%, and more pronouncedly, at 1% induced dilatation, hemorrhage and inflammation of the uterine wall. In conclusion, postpubertal long-term PM administration to Donryu rats exerts estrogenic effects in the mammary gland and uterus, and at a dose of 200 mg/kg b.w./day was found to promote mammary carcinogenesis initiated by DMBA. Full article
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Open AccessArticle Presence or Absence of mlr Genes and Nutrient Concentrations Co-Determine the Microcystin Biodegradation Efficiency of a Natural Bacterial Community
Toxins 2016, 8(11), 318; https://doi.org/10.3390/toxins8110318
Received: 3 October 2016 / Revised: 26 October 2016 / Accepted: 28 October 2016 / Published: 3 November 2016
Cited by 10 | Viewed by 1910 | PDF Full-text (1592 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlrA gene copies [...] Read more.
The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlrA gene copies was found with increasing microcystin concentrations. Among the 24 microcystin degrading strains isolated from the bacterial community, only 28% showed presence of mlrA gene, strongly supporting the existence and abundance of alternative microcystin degradation pathways in nature. In vitro degradation assays with both mlr+ and mlr bacterial genotypes (with presence and absence of the complete mlr gene cluster, respectively) were performed with four isolated strains (Sphingopyxis sp. IM-1, IM-2 and IM-3; Paucibacter toxinivorans IM-4) and two bacterial degraders from the culture collection (Sphingosinicella microcystinivorans Y2; Paucibacter toxinivorans 2C20). Differences in microcystin degradation efficiencies between genotypes were found under different total organic carbon and total nitrogen concentrations. While mlr+ strains significantly improved microcystin degradation rates when exposed to other carbon and nitrogen sources, mlr strains showed lower degradation efficiencies. This suggests that the presence of alternative carbon and nitrogen sources possibly competes with microcystins and impairs putative non-mlr microcystin degradation pathways. Considering the abundance of the mlr bacterial population and the increasing frequency of eutrophic conditions in aquatic systems, further research on the diversity of this population and the characterization and conditions affecting non-mlr degradation pathways deserves special attention. Full article
(This article belongs to the collection Marine and Freshwater Toxins)
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Open AccessArticle RNA Sequencing of Contaminated Seeds Reveals the State of the Seed Permissive for Pre-Harvest Aflatoxin Contamination and Points to a Potential Susceptibility Factor
Toxins 2016, 8(11), 317; https://doi.org/10.3390/toxins8110317
Received: 7 September 2016 / Revised: 26 October 2016 / Accepted: 28 October 2016 / Published: 3 November 2016
Cited by 4 | Viewed by 1771 | PDF Full-text (3336 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Pre-harvest aflatoxin contamination (PAC) is a major problem facing peanut production worldwide. Produced by the ubiquitous soil fungus, Aspergillus flavus, aflatoxin is the most naturally occurring known carcinogen. The interaction between fungus and host resulting in PAC is complex, and breeding for [...] Read more.
Pre-harvest aflatoxin contamination (PAC) is a major problem facing peanut production worldwide. Produced by the ubiquitous soil fungus, Aspergillus flavus, aflatoxin is the most naturally occurring known carcinogen. The interaction between fungus and host resulting in PAC is complex, and breeding for PAC resistance has been slow. It has been shown that aflatoxin production can be induced by applying drought stress as peanut seeds mature. We have implemented an automated rainout shelter that controls temperature and moisture in the root and peg zone to induce aflatoxin production. Using polymerase chain reaction (PCR) and high performance liquid chromatography (HPLC), seeds meeting the following conditions were selected: infected with Aspergillus flavus and contaminated with aflatoxin; and not contaminated with aflatoxin. RNA sequencing analysis revealed groups of genes that describe the transcriptional state of contaminated vs. uncontaminated seed. These data suggest that fatty acid biosynthesis and abscisic acid (ABA) signaling are altered in contaminated seeds and point to a potential susceptibility factor, ABR1, as a repressor of ABA signaling that may play a role in permitting PAC. Full article
(This article belongs to the collection Aflatoxins)
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