Toxins

21 pages, 1293 KiB

Open AccessArticle

RNA-Seq-Based Transcriptome Analysis of Aflatoxigenic Aspergillus flavus in Response to Water Activity

by Feng Zhang^1,†, Zhenni Guo^1,†, Hong Zhong¹, Sen Wang¹, Weiqiang Yang¹, Yongfeng Liu² and Shihua Wang^1,*

¹ Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China

² Shenzhen Key Laboratory of Bioenergy, BGI-Shenzhen, Shenzhen 518083, China

^† These authors contributed equally to this work.

Toxins 2014, 6(11), 3187-3207; https://doi.org/10.3390/toxins6113187 - 21 Nov 2014

Cited by 71 | Viewed by 10144

Abstract

Aspergillus flavus is one of the most important producers of carcinogenic aflatoxins in crops, and the effect of water activity (a_w) on growth and aflatoxin production of A. flavus has been previously studied. Here we found the strains under 0.93 a [...] Read more.

Aspergillus flavus is one of the most important producers of carcinogenic aflatoxins in crops, and the effect of water activity (a_w) on growth and aflatoxin production of A. flavus has been previously studied. Here we found the strains under 0.93 a_w exhibited decreased conidiation and aflatoxin biosynthesis compared to that under 0.99 a_w. When RNA-Seq was used to delineate gene expression profile under different water activities, 23,320 non-redundant unigenes, with an average length of 1297 bp, were yielded. By database comparisons, 19,838 unigenes were matched well (e-value < 10⁻⁵) with known gene sequences, and another 6767 novel unigenes were obtained by comparison to the current genome annotation of A. flavus. Based on the RPKM equation, 5362 differentially expressed unigenes (with |log₂Ratio| ≥ 1) were identified between 0.99 a_w and 0.93 a_w treatments, including 3156 up-regulated and 2206 down-regulated unigenes, suggesting that A. flavus underwent an extensive transcriptome response during water activity variation. Furthermore, we found that the expression of 16 aflatoxin producing-related genes decreased obviously when water activity decreased, and the expression of 11 development-related genes increased after 0.99 a_w treatment. Our data corroborate a model where water activity affects aflatoxin biosynthesis through increasing the expression of aflatoxin producing-related genes and regulating development-related genes. Full article

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14 pages, 886 KiB

Open AccessArticle

First Report of Cylindrospermopsin Production by Two Cyanobacteria (Dolichospermum mendotae and Chrysosporum ovalisporum) in Lake Iznik, Turkey

by Reyhan Akcaalan^1,*

, Latife Köker¹, Ayça Oğuz¹, Lisa Spoof², Jussi Meriluoto² and Meriç Albay¹

¹ Department of Freshwater Biology, Faculty of Fisheries, Istanbul University, Ordu Cad. No. 200, Laleli, Istanbul 34470, Turkey

² Department of Biosciences, Åbo Akademi University, Tykistökatu 6A, 20520 Turku, Finland

Toxins 2014, 6(11), 3173-3186; https://doi.org/10.3390/toxins6113173 - 18 Nov 2014

Cited by 46 | Viewed by 9335

Abstract

Cylindrospermopsin (CYN) is a cytotoxic alkaloid produced by cyanobacteria. The distribution of this toxin is expanding around the world and the number of cyanobacteria species producing this toxin is also increasing. CYN was detected for the first time in Turkey during the summer [...] Read more.

Cylindrospermopsin (CYN) is a cytotoxic alkaloid produced by cyanobacteria. The distribution of this toxin is expanding around the world and the number of cyanobacteria species producing this toxin is also increasing. CYN was detected for the first time in Turkey during the summer months of 2013. The responsible species were identified as Dolichospermum (Anabaena) mendotae and Chrysosporum (Aphanizomenon) ovalisporum. The D. mendotae increased in May, however, C. ovalisporum formed a prolonged bloom in August. CYN concentrations were measured by LC-MS/MS and ranged from 0.12 µg·mg⁻¹ to 4.92 µg·mg⁻¹ as dry weight, respectively. Both species were the only cyanobacteria actively growing and CYN production was attributed solely to these species. Despite CYN production by C. ovalisporum being a well-known phenomenon, to our knowledge, this is the first report of CYN found in D. mendotae bloom. Full article

(This article belongs to the Section Marine and Freshwater Toxins)

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16 pages, 877 KiB

Open AccessArticle

Screening a Strain of Aspergillus niger and Optimization of Fermentation Conditions for Degradation of Aflatoxin B₁

by Wei Zhang, Beibei Xue, Mengmeng Li, Yang Mu, Zhihui Chen, Jianping Li^* and Anshan Shan^*

Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030, China

Toxins 2014, 6(11), 3157-3172; https://doi.org/10.3390/toxins6113157 - 13 Nov 2014

Cited by 76 | Viewed by 9533

Abstract

Aflatoxin B₁, a type of highly toxic mycotoxin produced by some species belonging to the Aspergillus genus, such as Aspergillus flavus and Aspergillus parasiticus, is widely distributed in feed matrices. Here, coumarin was used as the sole carbon source to [...] Read more.

Aflatoxin B₁, a type of highly toxic mycotoxin produced by some species belonging to the Aspergillus genus, such as Aspergillus flavus and Aspergillus parasiticus, is widely distributed in feed matrices. Here, coumarin was used as the sole carbon source to screen microorganism strains that were isolated from types of feed ingredients. Only one isolate (ND-1) was able to degrade aflatoxin B₁ after screening. ND-1 isolate, identified as a strain of Aspergillus niger using phylogenetic analysis on the basis of 18S rDNA, could remove 26.3% of aflatoxin B₁ after 48 h of fermentation in nutrient broth (NB). Optimization of fermentation conditions for aflatoxin B₁ degradation by selected Aspergillus niger was also performed. These results showed that 58.2% of aflatoxin B₁ was degraded after 24 h of culture under the optimal fermentation conditions. The aflatoxin B₁ degradation activity of Aspergillus niger supernatant was significantly stronger than cells and cell extracts. Furthermore, effects of temperature, heat treatment, pH, and metal ions on aflatoxin B₁ degradation by the supernatant were examined. Results indicated that aflatoxin B₁ degradation of Aspergillus niger is enzymatic and this process occurs in the extracellular environment. Full article

(This article belongs to the Special Issue Detoxification of Mycotoxins)

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13 pages, 533 KiB

Open AccessArticle

Molecular and Insecticidal Characterization of a Novel Cry-Related Protein from Bacillus Thuringiensis Toxic against Myzus persicae

by Leopoldo Palma¹, Delia Muñoz², Colin Berry³, Jesús Murillo², Iñigo Ruiz De Escudero¹ and Primitivo Caballero^1,2,*

¹ Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, Campus Arrosadía, Mutilva 31192, Navarra, Spain

² Grupo de Protección Cultivos, Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, Pamplona 31006, Navarra, Spain

³ Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK

Toxins 2014, 6(11), 3144-3156; https://doi.org/10.3390/toxins6113144 - 6 Nov 2014

Cited by 38 | Viewed by 8722

Abstract

This study describes the insecticidal activity of a novel Bacillus thuringiensis Cry-related protein with a deduced 799 amino acid sequence (~89 kDa) and ~19% pairwise identity to the 95-kDa-aphidicidal protein (sequence number 204) from patent US 8318900 and ~40% pairwise identity to the [...] Read more.

This study describes the insecticidal activity of a novel Bacillus thuringiensis Cry-related protein with a deduced 799 amino acid sequence (~89 kDa) and ~19% pairwise identity to the 95-kDa-aphidicidal protein (sequence number 204) from patent US 8318900 and ~40% pairwise identity to the cancer cell killing Cry proteins (parasporins Cry41Ab1 and Cry41Aa1), respectively. This novel Cry-related protein contained the five conserved amino acid blocks and the three conserved domains commonly found in 3-domain Cry proteins. The protein exhibited toxic activity against the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae) with the lowest mean lethal concentration (LC₅₀ = 32.7 μg/mL) reported to date for a given Cry protein and this insect species, whereas it had no lethal toxicity against the Lepidoptera of the family Noctuidae Helicoverpa armigera (Hübner), Mamestra brassicae (L.), Spodoptera exigua (Hübner), S. frugiperda (J.E. Smith) and S. littoralis (Boisduval), at concentrations as high as ~3.5 μg/cm². This novel Cry-related protein may become a promising environmentally friendly tool for the biological control of M. persicae and possibly also for other sap sucking insect pests. Full article

(This article belongs to the Section Bacterial Toxins)

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15 pages, 633 KiB

Open AccessArticle

Rapid Analysis of Deoxynivalenol in Durum Wheat by FT-NIR Spectroscopy

by Annalisa De Girolamo^*

, Salvatore Cervellieri, Angelo Visconti and Michelangelo Pascale

Institute of Sciences of Food Production, National Research Council of Italy (ISPA-CNR), Via G. Amendola 122/O, 70126 Bari, Italy

Toxins 2014, 6(11), 3129-3143; https://doi.org/10.3390/toxins6113129 - 6 Nov 2014

Cited by 47 | Viewed by 8629

Abstract

Fourier-transform-near infrared (FT-NIR) spectroscopy has been used to develop quantitative and classification models for the prediction of deoxynivalenol (DON) levels in durum wheat samples. Partial least-squares (PLS) regression analysis was used to determine DON in wheat samples in the range of <50–16,000 µg/kg [...] Read more.

Fourier-transform-near infrared (FT-NIR) spectroscopy has been used to develop quantitative and classification models for the prediction of deoxynivalenol (DON) levels in durum wheat samples. Partial least-squares (PLS) regression analysis was used to determine DON in wheat samples in the range of <50–16,000 µg/kg DON. The model displayed a large root mean square error of prediction value (1,977 µg/kg) as compared to the EU maximum limit for DON in unprocessed durum wheat (i.e., 1,750 µg/kg), thus making the PLS approach unsuitable for quantitative prediction of DON in durum wheat. Linear discriminant analysis (LDA) was successfully used to differentiate wheat samples based on their DON content. A first approach used LDA to group wheat samples into three classes: A (DON ≤ 1,000 µg/kg), B (1,000 < DON ≤ 2,500 µg/kg), and C (DON > 2,500 µg/kg) (LDA I). A second approach was used to discriminate highly contaminated wheat samples based on three different cut-off limits, namely 1,000 (LDA II), 1,200 (LDA III) and 1,400 µg/kg DON (LDA IV). The overall classification and false compliant rates for the three models were 75%–90% and 3%–7%, respectively, with model LDA IV using a cut-off of 1,400 µg/kg fulfilling the requirement of the European official guidelines for screening methods. These findings confirmed the suitability of FT-NIR to screen a large number of wheat samples for DON contamination and to verify the compliance with EU regulation. Full article

(This article belongs to the Special Issue Recent Advances and Perspectives in Deoxynivalenol Research)

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12 pages, 662 KiB

Open AccessArticle

Measurement of Sterigmatocystin Concentrations in Urine for Monitoring the Contamination of Cattle Feed

by Yasuo Fushimi^1,2, Mitsuhiro Takagi^1,3,*, Seiichi Uno⁴, Emiko Kokushi⁴, Masayuki Nakamura⁵, Hiroshi Hasunuma², Urara Shinya^1,6, Eisaburo Deguchi^1,3 and Johanna Fink-Gremmels⁷

¹ United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi 753-8515, Japan

² Shepherd Central Livestock Clinic, Kagoshima 899-1611, Japan

³ Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan

⁴ Faculty of Fisheries, Kagoshima University, Kagoshima 890-0056, Japan

⁵ Faculty of Agriculture, Kagoshima University, Kagoshima 890-0056, Japan

⁶ Soo Agriculture Mutual Aid Association, Kagoshima 899-8212, Japan

⁷ Faculty of Veterinary Medicine, Utrecht University, Yalelaan 104, The Netherlands

Toxins 2014, 6(11), 3117-3128; https://doi.org/10.3390/toxins6113117 - 4 Nov 2014

Cited by 15 | Viewed by 6339

Abstract

This study aimed (1) at determining the levels of the fungal toxin sterigmatocystin (STC) in the feed and urine of cattle and (2) at evaluating the effects of supplementing the feed with a mycotoxin adsorbent (MA) on STC concentrations in urine. Two herds [...] Read more.

This study aimed (1) at determining the levels of the fungal toxin sterigmatocystin (STC) in the feed and urine of cattle and (2) at evaluating the effects of supplementing the feed with a mycotoxin adsorbent (MA) on STC concentrations in urine. Two herds of female Japanese Black cattle were used in this study. The cattle in each herd were fed a standard ration containing rice straw from different sources and a standard concentrate; two groups of cattle from each herd (n = six per group) received the commercial MA, mixed with the concentrate or given as top-dressing, whereas a third group received no supplement and served as control. Urine and feed samples were collected at various time points throughout the experiment. STC concentrations were measured using liquid chromatography-tandem mass spectrometry (LC-TMS). STC concentrations in straw were higher in Herd 1 (range 0.15–0.24 mg/kg DM) than in Herd 2 (range <0.01–0.06 mg/kg DM). In Herd 1, STC concentrations in urine significantly declined 2 weeks after replacing the contaminated feed, whereas MA supplementation had no effect. In conclusion, mycotoxins in urine samples are useful biological markers for monitoring the systemic exposure of cattle to multiple mycotoxins, as well as evaluating the effectiveness of interventions. Full article

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19 pages, 1200 KiB

Open AccessReview

Uptake and Processing of the Cytolethal Distending Toxin by Mammalian Cells

by Joseph M. DiRienzo

Department of Microbiology, School of Dental Medicine, University of Pennsylvania, 240 South 40th Street, Philadelphia, PA 19104, USA

Toxins 2014, 6(11), 3098-3116; https://doi.org/10.3390/toxins6113098 - 31 Oct 2014

Cited by 38 | Viewed by 8371

Abstract

The cytolethal distending toxin (Cdt) is a heterotrimeric holotoxin produced by a diverse group of Gram-negative pathogenic bacteria. The Cdts expressed by the members of this group comprise a subclass of the AB toxin superfamily. Some AB toxins have hijacked the retrograde transport [...] Read more.

The cytolethal distending toxin (Cdt) is a heterotrimeric holotoxin produced by a diverse group of Gram-negative pathogenic bacteria. The Cdts expressed by the members of this group comprise a subclass of the AB toxin superfamily. Some AB toxins have hijacked the retrograde transport pathway, carried out by the Golgi apparatus and endoplasmic reticulum (ER), to translocate to cytosolic targets. Those toxins have been used as tools to decipher the roles of the Golgi and ER in intracellular transport and to develop medically useful delivery reagents. In comparison to the other AB toxins, the Cdt exhibits unique properties, such as translocation to the nucleus, that present specific challenges in understanding the precise molecular details of the trafficking pathway in mammalian cells. The purpose of this review is to present current information about the mechanisms of uptake and translocation of the Cdt in relation to standard concepts of endocytosis and retrograde transport. Studies of the Cdt intoxication process to date have led to the discovery of new translocation pathways and components and most likely will continue to reveal unknown features about the mechanisms by which bacterial proteins target the mammalian cell nucleus. Insight gained from these studies has the potential to contribute to the development of novel therapeutic strategies. Full article

(This article belongs to the Special Issue Intracellular Traffic and Transport of Bacterial Protein Toxins)

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21 pages, 780 KiB

Open AccessArticle

PhTX-II a Basic Myotoxic Phospholipase A₂ from Porthidium hyoprora Snake Venom, Pharmacological Characterization and Amino Acid Sequence by Mass Spectrometry

by Salomón Huancahuire-Vega^1,2,*, Luis Alberto Ponce-Soto¹ and Sergio Marangoni¹

¹ Department of Biochemistry, Institute of Biology, State University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil

² Department of Biochemistry and Pharmacology, Faculty of Health Sciences, Medicine School, Union Peruvian University (UPeU), Lima 15, Peru

Toxins 2014, 6(11), 3077-3097; https://doi.org/10.3390/toxins6113077 - 31 Oct 2014

Cited by 10 | Viewed by 6117

Abstract

A monomeric basic PLA₂ (PhTX-II) of 14149.08 Da molecular weight was purified to homogeneity from Porthidium hyoprora venom. Amino acid sequence by in tandem mass spectrometry revealed that PhTX-II belongs to Asp49 PLA₂ enzyme class and displays conserved domains as the [...] Read more.

A monomeric basic PLA₂ (PhTX-II) of 14149.08 Da molecular weight was purified to homogeneity from Porthidium hyoprora venom. Amino acid sequence by in tandem mass spectrometry revealed that PhTX-II belongs to Asp49 PLA₂ enzyme class and displays conserved domains as the catalytic network, Ca²⁺-binding loop and the hydrophobic channel of access to the catalytic site, reflected in the high catalytic activity displayed by the enzyme. Moreover, PhTX-II PLA₂ showed an allosteric behavior and its enzymatic activity was dependent on Ca²⁺. Examination of PhTX-II PLA₂ by CD spectroscopy indicated a high content of alpha-helical structures, similar to the known structure of secreted phospholipase IIA group suggesting a similar folding. PhTX-II PLA₂ causes neuromuscular blockade in avian neuromuscular preparations with a significant direct action on skeletal muscle function, as well as, induced local edema and myotoxicity, in mice. The treatment of PhTX-II by BPB resulted in complete loss of their catalytic activity that was accompanied by loss of their edematogenic effect. On the other hand, enzymatic activity of PhTX-II contributes to this neuromuscular blockade and local myotoxicity is dependent not only on enzymatic activity. These results show that PhTX-II is a myotoxic Asp49 PLA₂ that contributes with toxic actions caused by P. hyoprora venom. Full article

(This article belongs to the Section Animal Venoms)

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19 pages, 891 KiB

Open AccessReview

Chemical Compounds Toxic to Invertebrates Isolated from Marine Cyanobacteria of Potential Relevance to the Agricultural Industry

by Magbubah Essack^†

, Hanin S. Alzubaidy^†, Vladimir B. Bajic and John A. C. Archer^*

¹ Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Jeddah, Saudi Arabia

^† These authors contributed equally to this work.

Toxins 2014, 6(11), 3058-3076; https://doi.org/10.3390/toxins6113058 - 29 Oct 2014

Cited by 10 | Viewed by 7718

Abstract

In spite of advances in invertebrate pest management, the agricultural industry is suffering from impeded pest control exacerbated by global climate changes that have altered rain patterns to favour opportunistic breeding. Thus, novel naturally derived chemical compounds toxic to both terrestrial and aquatic [...] Read more.

In spite of advances in invertebrate pest management, the agricultural industry is suffering from impeded pest control exacerbated by global climate changes that have altered rain patterns to favour opportunistic breeding. Thus, novel naturally derived chemical compounds toxic to both terrestrial and aquatic invertebrates are of interest, as potential pesticides. In this regard, marine cyanobacterium-derived metabolites that are toxic to both terrestrial and aquatic invertebrates continue to be a promising, but neglected, source of potential pesticides. A PubMed query combined with hand-curation of the information from retrieved articles allowed for the identification of 36 cyanobacteria-derived chemical compounds experimentally confirmed as being toxic to invertebrates. These compounds are discussed in this review. Full article

(This article belongs to the Section Marine and Freshwater Toxins)

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17 pages, 723 KiB

Open AccessArticle

Dynamics of the Toxin Cylindrospermopsin and the Cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum in a Mediterranean Eutrophic Reservoir

by Ali Fadel^1,2, Ali Atoui¹

, Bruno J. Lemaire^2,3, Brigitte Vinçon-Leite² and Kamal Slim^1,*

¹ Laboratory of Microorganisms and Food Irradiation, Lebanese Atomic Energy Commission-CNRS, P.O. Box 11-8281, Riad El Solh, Beirut 1107 2260, Lebanon

² LEESU (UMR MA-102) Université Paris-Est, Ecole des Ponts ParisTech, AgroParisTech, Marne-la-Vallée F-77455, France

³ Department of Forest, Water and Environmental Sciences and Engineering, AgroParisTech, Paris F-75005, France

Toxins 2014, 6(11), 3041-3057; https://doi.org/10.3390/toxins6113041 - 28 Oct 2014

Cited by 29 | Viewed by 7754

Abstract

Chrysosporum ovalisporum is a cylindrospermopsin toxin producing cyanobacterium that was reported in several lakes and reservoirs. Its growth dynamics and toxin distribution in field remain largely undocumented. Chrysosporum ovalisporum was reported in 2009 in Karaoun Reservoir, Lebanon. We investigated the factors controlling [...] Read more.

Chrysosporum ovalisporum is a cylindrospermopsin toxin producing cyanobacterium that was reported in several lakes and reservoirs. Its growth dynamics and toxin distribution in field remain largely undocumented. Chrysosporum ovalisporum was reported in 2009 in Karaoun Reservoir, Lebanon. We investigated the factors controlling the occurrence of this cyanobacterium and vertical distribution of cylindrospermopsin in Karaoun Reservoir. We conducted bi-weekly sampling campaigns between May 2012 and August 2013. Results showed that Chrysosporum ovalisporum is an ecologically plastic species that was observed in all seasons. Unlike the high temperatures, above 26 °C, which is associated with blooms of Chrysosporum ovalisporum in Lakes Kinneret (Israel), Lisimachia and Trichonis (Greece) and Arcos Reservoir (Spain), Chrysosporum ovalisporum in Karaoun Reservoir bloomed in October 2012 at a water temperature of 22 °C during weak stratification. Cylindrospermopsin was detected in almost all water samples even when Chrysosporum ovalisporum was not detected. Chrysosporum ovalisporum biovolumes and cylindrospermopsin concentrations were not correlated (n = 31, r² = −0.05). Cylindrospermopsin reached a maximum concentration of 1.7 µg L⁻¹. The vertical profiles of toxin concentrations suggested its possible degradation or sedimentation resulting in its disappearance from the water column. The field growth conditions of Chrysosporum ovalisporum in this study revealed that it can bloom at the subsurface water temperature of 22 °C increasing the risk of its development and expansion in lakes located in temperate climate regions. Full article

(This article belongs to the Special Issue Harmful Algal Blooms (HABs) and Public Health: Progress and Current Challenges)

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Toxins, Volume 6, Issue 11 (November 2014) – 10 articles , Pages 3041-3207

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