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To determine the molecular basis for the phenomenon of non-production of aflatoxin in certain members of the Aspergillus (A.)flavus group of the fungi with a view to understanding the global regulation of toxin synthesis and the convergent evolution of aflatoxin biosynthesis.
Approach:
The present proposal is centered upon previously isolated Apergillus (A.) parasiticus sec- (for secondary metabolism minus) strains, that display altered morphology and sporulation. Recent work from our laboratory has shown that a mutation in aflR coding or promoter region is not responsible for the sec-phenotype. Yet, the aflR expression is lowered in the sec-strains. There is no expression of the aflatoxin pathway genes, and aflR overexpression does not reverse the sec- phenotype. Preliminary results have also revealed clear differences between the sec- and their parental sec+ (for secondary metabolism plus) total protein-profiles. Proteomics and microarray technology will be used to determine the differences between sec+ and sec- strains at the molecular level. These differences will provide insights into the global regulatory mechanisms governing aflatoxin synthesis.