Naresh Magan, David Aldred, Russell Hope and David Mitchell
Article: Environmental Factors and Interactions with Mycobiota of Grain and Grapes: Effects on Growth, Deoxynivalenol and Ochratoxin Production by Fusarium culmorum and Aspergillus carbonarius
Toxins 2010, 2(3), 353-366; doi:10.3390/toxins2030353 - published online 18 March 2010
Show/Hide AbstractAbstract: Mycotoxigenic fungi colonizing food matrices are inevitably competing with a wide range of other resident fungi. The outcomes of these interactions are influenced by the prevailing environmental conditions and the competing species. We have evaluated the competitiveness of F. culmorum and A. carbonarius in the grain and grape food chain for their in vitro and in situ dominance in the presence of other fungi, and the effect that such interactions have on colony interactions, growth and deoxynivalenol (DON) and ochratoxin A (OTA) production. The Index of Dominance shows that changes in water activity (a_w) and temperature affect the competitiveness of F. culmorum and A. carbonarius against up to nine different fungi. Growth of both mycotoxigenic species was sometimes inhibited by the presence of other competing fungi. For example, A. niger uniseriate and biseriate species decreased growth of A. carbonarius, while Aureobasidium pullulans and Cladosporium species stimulated growth. Similar changes were observed when F. graminearum was interacting with other grain fungi such as Alternaria alternata, Cladopsorium herbarum and Epicoccum nigrum. The impact on DON and OTA production was very different. For F. culmorum, the presence of other species often inhibited DON production over a range of environmental conditions. For A.carbonarius, on a grape–based medium, the presence of certain species resulted in a significant stimulation of OTA production. However, this was influenced by both temperature and a_w level. This suggests that the final mycotoxin concentrations observed in food matrices may be due to complex interactions between species and the environmental history of the samples analyzed.

Daniel Grenier and Shin-ichi Tanabe
Article: Porphyromonas gingivalis Gingipains Trigger a Proinflammatory Response in Human Monocyte-derived Macrophages Through the p38α Mitogen-activated Protein Kinase Signal Transduction Pathway
Toxins 2010, 2(3), 341-352; doi:10.3390/toxins2030341 - published online 10 March 2010
Show/Hide AbstractAbstract: Porphyromonas gingivalis, the major etiologic agent of chronic periodontitis, produces a broad spectrum of virulence factors, including Arg- and Lys-gingipain cysteine proteinases. In this study, we investigated the capacity of P. gingivalis gingipains to trigger a proinflammatory response in human monocyte-derived macrophages. Both Arg- and Lys-gingipain preparations induced the secretion of TNF-α and IL-8 by macrophages. Stimulation of macrophages with Arg-gingipain A/B preparation at the highest concentration was associated with lower amounts of cytokines detected, a phenomenon likely related to proteolytic degradation. The inflammatory response induced by gingipains was not dependent of their catalytic activity since heat-inactivated preparations were still effective. Stimulating macrophages with gingipain preparations was associated with increased levels of phosphorylated p38α MAPK suggesting its involvement in cell activation. In conclusion, our study brought clear evidence that P. gingivalis Arg- and Lys-gingipains may contribute to the host inflammatory response, a critical factor in periodontitis-associated tissue destruction.

Peter G. Mantle, Cyrille Amerasinghe, Amy L. Brown, Diana Herman, Thomas Horn, Thoger Krogh, Edward W. Odell, Tomas Rosenbaum and Calin A. Tatu
Article: A Pilot Study of Nuclear Instability in Archived Renal and Upper Urinary Tract Tumours with Putative Ochratoxin Aetiology
Toxins 2010, 2(3), 326-340; doi:10.3390/toxins2030326 - published online 9 March 2010
Show/Hide AbstractAbstract: DNA ploidy measurement has been applied uniquely to wax-embedded tissue of primary renal cell and metastatic tumours of a key experimental researcher on porcine ochratoxicosis, a control, and four transitional cell carcinomas from cases of Balkan endemic nephropathy. Primary renal tumour was diploid, and hyperdiploid metastasis was within the lower ploidy range for typical renal cell carcinoma. Three Balkan primary tumours showed extensive aneuploidy indicating marked nuclear instability, similar to model rat renal carcinoma caused by ochratoxin A. In contrast, much less nuclear instability in the putative occupational ochratoxicosis case fitted poorly with the ochratoxin A model.

Naomi L. B. Wernick, Daniel J.-F. Chinnapen, Jin Ah Cho and Wayne I. Lencer
Review: Cholera Toxin: An Intracellular Journey into the Cytosol by Way of the Endoplasmic Reticulum
Toxins 2010, 2(3), 310-325; doi:10.3390/toxins2030310 - published online 5 March 2010
Show/Hide AbstractAbstract: Cholera toxin (CT), an AB₅-subunit toxin, enters host cells by binding the ganglioside GM1 at the plasma membrane (PM) and travels retrograde through the trans-Golgi Network into the endoplasmic reticulum (ER). In the ER, a portion of CT, the enzymatic A1-chain, is unfolded by protein disulfide isomerase and retro-translocated to the cytosol by hijacking components of the ER associated degradation pathway for misfolded proteins. After crossing the ER membrane, the A1-chain refolds in the cytosol and escapes rapid degradation by the proteasome to induce disease by ADP-ribosylating the large G-protein Gs and activating adenylyl cyclase. Here, we review the mechanisms of toxin trafficking by GM1 and retro-translocation of the A1-chain to the cytosol.

George P. Anderson, Vasudha A. Kowtha and Chris R. Taitt
Communication: Detection of Fumonisin B1 and Ochratoxin A in Grain Products Using Microsphere-Based Fluid Array Immunoassays
Toxins 2010, 2(2), 297-309; doi:10.3390/toxins2020297 - published online 25 February 2010
Show/Hide AbstractAbstract: Grain products are a staple of diets worldwide and therefore, the ability to accurately and efficiently detect foodborne contaminants such as mycotoxins is of importance to everyone. Here we describe an indirect competitive fluid array fluoroimmunoassay to quantify the mycotoxins, fumonisin B1 and ochratoxin A. Both toxins were immobilized to the surface of microspheres using a variety of intermediate molecules and binding of biotinylated "tracer" antibody tracers determined through flow cytometry using streptavidin-phycoerythrin conjugates and the Luminex100 flow cytometer. Competitive assays were developed where the binding of biotinylated monoclonal antibodies to fumonisin B and ochratoxin A was competitively inhibited by different concentrations of those toxins in solution. Concentrations of fumonisin giving 50% inhibition were 300 pg/mL in buffer, 100 ng/g in spiked oats, and 1 μg/g in spiked cornmeal; analogous concentrations for ochratoxin A were 30 ng/mL in buffer, 30 ng/g in spiked oats, and 10 ng/g in spiked corn. The future challenge will be to expand the number of mycotoxins tested both individually and in multiplexed format using this platform.

Alessia Fabbri, Sara Travaglione and Carla Fiorentini
Article: Escherichia coli Cytotoxic Necrotizing Factor 1 (CNF1): Toxin Biology, in Vivo Applications and Therapeutic Potential
Toxins 2010, 2(2), 283-296; doi:10.3390/toxins2020282 - published online 23 February 2010
Show/Hide AbstractAbstract: CNF1 is a protein toxin produced by certain pathogenic strains of Escherichia coli. It permanently activates the regulatory Rho, Rac, and Cdc42 GTPases in eukaryotic cells, by deamidation of a glutamine residue. This modification promotes new activities in cells, such as gene transcription, cell proliferation and survival. Since the Rho GTPases play a pivotal role also in several processes in vivo, the potentiality of CNF1 to act as a new pharmacological tool has been explored in experimental animals and in diverse pathological contexts. In this review, we give an update overview on the potential in vivo applications of CNF1.