Xuehuan Feng

Publication Date


Document Type


First Advisor

Calvo, Ana M.

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Biological Sciences


Aspergillus nidulans--Development; Fungi--Reproduction; Developmental biology


The model filamentous fungus Aspergillus nidulans synthesizes a variety of secondary metabolites, including the mycotoxin sterigmatocystin (ST). The production of this toxin is positively controlled by veA, a global regulatory gene that also governs sexual and asexual development in A. nidulans. In the absence of veA (ΔveA), ST biosynthesis is blocked. Previously we performed random mutagenesis in a [Delta]veA strain and identified several revertant mutants that are able to synthesize ST, among them RM1. Complementation of RM1 with a genomic library revealed that the mutation occurred in the coding region of a gene, putatively involved in polysaccharide biosynthesis, designated as cpsA. While in the [Delta]veA genetic background deletion of cpsA restores ST production, in a veA wild-type background absence of cpsA reduces and delays ST biosynthesis by decreasing the expression of ST clustered genes. Furthermore, cpsA is also necessary for the production of other secondary metabolites, including penicillin, affecting the expression of PN biosynthetic genes. Besides its role in secondary metabolism, cpsA is necessary for normal asexual and sexual development in this model fungus. Furthermore, chemical and microscopy analyses revealed that cpsA is required for normal composition and integrity of the A. nidulans cell wall, affecting biofilm formation and sensitivity to oxidative stress. Our studies confirmed that the cpsA gene product is the first functional hyaluronan synthase described in Ascomycetes, and its role in maintaining the integrity of the cell wall has a major influence on other fungal biological processes. The conservation of cpsA in other Ascomycetes suggests that cpsA homologs might have similar roles in other fungal species.


Advisors: Ana M. Calvo.||Committee members: Eduardo A. Espeso; Shaojie Li; Yanbin Yin; Shengde Zhou.||Includes bibliographical references.||Includes illustrations.


viii, 75 pages




Northern Illinois University

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