Staff publications - Cranfield Health

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Browsing Staff publications - Cranfield Health by Publisher "MDPI"

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    Control of Aflatoxin Production of Aspergillus flavus and Aspergillus parasiticus Using RNA Silencing Technology by Targeting aflD (nor-1) Gene.
    (MDPI , 2011-06-30T00:00:00Z) Abdel-Hadi, Ahmed; Caley, D. P.; Carter, D. R.; Magan, Naresh
    Aspergillus flavus and Aspergillus parasiticus are important pathogens of cotton, corn, peanuts and other oil-seed crops, producing toxins both in the field and during storage. We have designed three siRNA sequences (Nor-Ia, Nor-Ib, Nor-Ic) to target the mRNA sequence of the aflD gene to examine the potential for using RNA silencing technology to control aflatoxin production. Thus, the effect of siRNAs targeting of two key genes in the aflatoxin biosynthetic pathway, aflD (structural) and aflR (regulatory gene) and on aflatoxin B(1 )(AFB(1)), and aflatoxin G(1) (AFG(1)) production was examined. The study showed that Nor-Ib gave a significant decrease in aflD mRNA, aflR mRNA abundance, and AFB(1) production (98, 97 and 97% when compared to the controls) in A. flavus NRRL3357, respectively. Reduction in aflD and aflR mRNA abundance and AFB(1 )production increased with concentration of siRNA tested. There was a significant inhibition in aflD and AFB(1) production by A. flavus EGP9 and AFG(1 )production by A. parasiticus NRRL 13005. However, there was no significant decrease in AFG(1) production by A. parasiticus SSWT 2999. Changes in AFB(1) production in relation to mRNA levels of aflD showed a good correlation (R = 0.88; P = 0.00001); changes in aflR mRNA level in relation to mRNA level of aflD also showed good correlation (R = 0.82; P = 0.0001). The correlations between changes in aflR and aflD gene expression suggests a strong relationship between these structural and regulatory genes, and that aflD could be used as a target gene to develop efficient means for aflatoxin control using RNA silencing technolog
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    Development of an electrochemical immunosensor for fumonisins detection in foods
    (MDPI , 2010-04-30T00:00:00Z) Kadir, Mohamad Kamal Abdul; Tothill, Ibtisam E.
    An electrochemical affinity sensor for the determination of fumonisins mycotoxins (Fms) using monoclonal antibody modified screen-printed gold electrode with carbon counter and silver-silver chloride pseudo-reference electrode is reported in this work. A direct competitive enzyme-linked immunosorbent assay (ELISA) was initially developed, exhibiting a detection limit of 100 µg·L-1for fumonisins. This was then transferred to the surface of a bare gold screen-printed electrode (SPGE) and detection was performed by chronoamperometry, monitoring the reaction of 3,3',5,5'-Tetramethylbenzidine dihydrochloride (TMB) and hydrogen peroxide (H2O2) catalysed by HRP at -100 mV potential vs. onboard Ag-AgCl pseudo-reference electrode. The immunosensor exhibited detection limit of 5 µg·L-1 fumonisins with a dynamic range from 1 µg·L-1-1000 µg·L-1. The sensor also performed well in extracted corn
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    Environmental factors and interactions with mycobiota of grain and grapes: Effects on growth, deoxynivalenol and ochratoxin production by Fusarium culmorum and Aspergillus carbonarius
    (MDPI , 2010-03-18T00:00:00Z) Magan, Naresh; Aldred, David; Hope, Russell; Mitchell, David
    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 (aw) 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 aw 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.
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    Gene-regulatory activity of alpha-tocopherol.
    (MDPI, 2010-03-12T00:00:00Z) Rimbach, G.; Moehring, J.; Huebbe, P.; Lodge, John K.
    Vitamin E is an essential vitamin and a lipid soluble antioxidant, at least, under in vitro conditions. The antioxidant properties of vitamin E are exerted through its phenolic hydroxyl group, which donates hydrogen to peroxyl radicals, resulting in the formation of stable lipid species. Beside an antioxidant role, important cell signalling properties of vitamin E have been described. By using gene chip technology we have identified alpha-tocopherol sensitive molecular targets in vivo including christmas factor (involved in the blood coagulation) and 5alpha-steroid reductase type 1 (catalyzes the conversion of testosterone to 5alpha-dihydrotestosterone) being upregulated and gamma-glutamyl-cysteinyl synthetase (the rate limiting enzyme in GSH synthesis) being downregulated due to alpha-tocopherol deficiency. Alpha-tocopherol regulates signal transduction cascades not only at the mRNA but also at the miRNA level since miRNA 122a (involved in lipid metabolism) and miRNA 125b (involved in inflammation) are downregulated by alpha-tocopherol. Genetic polymorphisms may determine the biological and gene-regulatory activity of alpha-tocopherol. In this context we have recently shown that genes encoding for proteins involved in peripheral alpha-tocopherol transport and degradation are significantly affected by the apoE genotype.