A bovine udder infected with Aspergillus fumigatus was analysed by physico-chemical methods (thin layer chromatography, high performance liquid chromatography and direct exposure probe--mass spectrometry) for the presence of mycotoxins. Gliotoxin, a fungal metabolite with cytotoxic and immunosuppressive properties was isolated for the first time from naturally infected tissue. The gliotoxin concentration analysed (9-2 mgkg -1 udder) was approximately 100 times higher than the concentration known to produce morphological changes of cells. Gliotoxin may play an important role in the establishment and development of an infection with A fumigatus.Aspergillus fumigatus belongs to a group of filamentous fungi which are normally saprophytes in nature (soil, plants, air). Invasive aspergillosis involving the respiratory system, central nervous system, cardiovascular system, urinary tract, genital tract, skin, bone, liver or eye of man and animals is an opportunistic infection and has been well documented, especially in immunosuppressed patients [1,5,7,8]. Various mycotoxins such as fumitremorgins, TR-2 toxin, verruculogen, tryptoquivalines, fumiclavines, gliotoxin, kojic acid, fumigatins, spinulosins, helvolic acid or fumagillin have been isolated from cultures of A. fumigatus [4] and the role of these toxic fungal metabolites as virulence factors during infection has been discussed previously [5,7,19].Recently, the production of a haemolytic toxin, ofA. fumigatus, asp-haemolysin, has been demonstrated in experimentally infected mice by immunohistochemistry [ 17].This report describes the isolation of gliotoxin, a highly cytotoxic and immunosuppressive mycotoxin [ 11,12,15], from the udder of a cow which was naturally infected with the fungus A. fumigatus.
Increasingly, new evidence has demonstrated variability in the epitope regions of bacterial flagellin, including in regions harboring the microbe-associated molecular patterns flg22 and flgII-28 that are recognized by the pattern recognition receptors FLS2 and FLS3, respectively. Additionally, since bacterial motility is known to contribute to pathogen virulence and chemotaxis, reductions in or loss of motility can significantly reduce bacterial fitness. In this study, we determined that variations in flg22 and flgII-28 epitopes allow some, but not all, Xanthomonas species to evade both FLS2-and FLS3-mediated oxidative burst responses. We observed variation in the motility for many isolates, irrespective of their flagellin sequence. Instead, we determined that past growth conditions may have a significant impact on the motility status of isolates, as we could minimize this variability by inducing motility using chemoattractant assays. Additionally, motility could be significantly suppressed under nutrient-limited conditions, and bacteria could “remember” its prior motility status after storage at ultra-cold temperatures. Finally, we observed larger bacterial populations of strains with flagellin variants predicted not to be recognized by either FLS2 or FLS3, suggesting that these bacteria can evade flagellin recognition in tomato plants. While some flagellin variants may impart altered motility and differential recognition by the host immune system, external growth parameters and gene expression regulation appear to have more significant impacts on the motility phenotypes for these Xanthomonas species.
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