Metal ions modulate gene expression and accumulation of the mycotoxins aflatoxin and zearalenone.
OBJECTIVE
To determine the modulating action of some metal ions (Zn+2, Fe+2, Cu+2) on gene expression of enzymes related to fungal growth and accumulation of the mycotoxins aflatoxin and zearalenone.


RESULTS
The effect of the metal ions, as single or mixed treatments, was observed in submerged cultures of toxigenic Aspergillus flavus or Fusarium graminearum, which produce the mycotoxins aflatoxin or zearalenone, respectively. The enzyme-linked immunosorbent assay results showed that the single metals Zn+2 or Cu+2 stimulated aflatoxin accumulation while Cu+2 or Fe+2 stimulated zearalenone in fungal cultures. Single Zn+2 treatment also affected conidial differentiation and pigmentation. A cDNA suppression subtractive library was also produced and followed by sequencing of potential metal treatment-specific clones, thus determining induced genes. The genes uncovered included enzymes and regulators of cell growth and division, including many genes with unknown functions were uncovered. A Northern blot analysis was used to verify the expression pattern of the corresponding genes under metal treatment. The metal ions enhanced the expression of alcohol dehydrogenase Adh1 homologue by up to 33-fold in A. flavus and ca fourfold in F. graminearum. Encoding homologues of a neutral amino acid permease, were also used in the Northern analysis. However, the expression of the permease was not significantly affected by metal ion treatments.


CONCLUSIONS
The results showed a significant effect of metal ions on expression of gene related to fungal growth, development, conidiation and production of both aflatoxin and zearalenone.


CONCLUSIONS
At the molecular and cellular level, the significant effects of metal ions on fungal growth and development, conidiation, and production of both aflatoxin and zearalenone were demonstrated.
Cuero
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Prairie View A & M University, CARC, Texas A & M University System, Prairie View, TX 77446, USA. olimpa@aol.com
Ouellet
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D000348:Aflatoxins / Q000235:genetics*; D001231:Aspergillus flavus / Q000235:genetics / Q000254:growth & development; D015152:Blotting, Northern / Q000379:methods; D003300:Copper / Q000494:pharmacology; D005506:Food Contamination; D005516:Food Microbiology; D005670:Fusarium / Q000235:genetics / Q000254:growth & development; D015870:Gene Expression / Q000187:drug effects; D015723:Gene Library; D005800:Genes, Fungal; D006801:Humans; D007477:Ions; D007501:Iron / Q000494:pharmacology; D008670:Metals / Q000494:pharmacology*; D009183:Mycotoxins / Q000235:genetics*; D015025:Zearalenone / Q000235:genetics*; D015032:Zinc / Q000494:pharmacology
D000348:Aflatoxins; D007477:Ions; D008670:Metals; D009183:Mycotoxins; D015025:Zearalenone; D003300:Copper; D007501:Iron; D015032:Zinc