Project description:Mycotic leratitis is the corneal inflammation predominantly caused by Fusarium and Aspergillus species. Corneal epithelium is the earliest cell type encounter the invading pathogen. The innate immune responses of human corneal epithelial cells against Aspergillus flavus is not known. Here we studied the role of human corneal epithelial cells against Aspergillus flavus infection. The results showed that corneal epithelial cells internalized Aspergillus flavus conidia through actin mediated polymerization surrounding the conidia. Further the actin inhibitor cytochalasin D treatment reduced the formation actin ring around the conidia. The engulfed conidia acquired endosomal proteins as revealed by immunofluorescence analsyisis. Mass spectromtery of phagosomal proteins confirmed the recruitment of endosomal proteins and other proteins involved in phagocytosis. These results show the involvement of corneal epithelial cells in anti fungal defense.
Project description:Linking cell reproduction and survival is a key task of all life forms. All fungi in the genus Aspergillus reproduce by forming asexual spores called conidia, of which formation is governed by the central regulatory circuit, BrlA->AbaA->WetA. Here, we report that WetA is a key multi-functional regulator that bridged spore differentiation, long-term survival, and chemical development in Aspergillus flavus.
Project description:Aspergillus flavus and A. parasiticus are two of the most important aflatoxin-producing species that contaminate agricultural commodities worldwide. Both species are heterothallic and undergo sexual reproduction in laboratory crosses. Here, we examine the possibility of interspecific matings between A. flavus and A. parasiticus. These species can be distinguished morphologically and genetically, as well as by their mycotoxin profiles. Aspergillus flavus produces both B aflatoxins and cyclopiazonic acid (CPA), B aflatoxins or CPA alone, or neither mycotoxin; Aspergillus parasiticus produces B and G aflatoxins or the aflatoxin precursor O-methylsterigmatocystin, but not CPA. Only four out of forty-five attempted interspecific crosses between compatible mating types of A. flavus and A. parasiticus were fertile and produced viable ascospores. Single ascospore strains from each cross were isolated and were shown to be recombinant hybrids using multilocus genotyping and array comparative genome hybridization. Conidia of parents and their hybrid progeny were haploid and predominantly monokaryons and dikaryons based on flow cytometry. Multilocus phylogenetic inference showed that experimental hybrid progeny were grouped with naturally occurring A. flavus L strain and A. parasiticus. Higher total aflatoxin concentrations in some F1 progeny strains compared to midpoint parent aflatoxin levels indicate synergism in aflatoxin production; moreover, three progeny strains synthesized G aflatoxins that were not produced by the parents, and there was evidence of putative allopolyploidization in one strain. These results suggest that hybridization is an important diversifying force resulting in the genesis of novel toxin profiles in these agriculturally important species.