Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 165-188). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 190-217). Available also in a digital version from Dissertation Abstracts.

Carotenoid pigments in W. dermatitidis, the first pathogenic, dematiaceous fungus in which carotenoid pigments nave been reported, are located primarily (81%) in lipid organelles which floated on the surface of the supernatant fraction of lysed cells. Pigment in this fraction could be extracted with ethyl ether without prior treatment with acetone indicating the pigment is unbound in the lipid organelle. Eight percent remains after exhaustive ether extraction and is recovered after the sample is treated with acetone indicating this fraction is non-covalently bound to proteins in the membranes associated with the lipid organelle. The remaining pigment (about 12%) represents contamination of the supernatant with the lipid organelles.

Carotenoids in W. dermatitids were found to be associated with membranes of lipid globules and/or proteins dispersed in the lipids in the yeast-phase of the organism. The lipid globules increase in size and the pigment concentrations increase with age of the cell. Electron micrographs show these organelles to be surrounded by a single unit membrane. The free carotenoids are extractable with ethyl ether from pigmented fractions of osmotically ruptured protoplasts only after the sample has been treated with acetone, indicating the pigment is non-covalently bound, presumably to a protein.

Not available / text

To study the function of WdStuAp and WdPacCp in Wangiella dermatitidis, a black, polymorphic fungal pathogen of humans with yeast phase predominance, WdSTUA and WdPACC were cloned, sequenced, disrupted and expressed. WdStuAp was most similar to the APSES proteins of Aspergillus species and its APSES DNA-binding domain was located in its N-terminal half. Deletion of WdSTUA in W. dermatitidis induced convoluted instead of normal smooth colony surface growth on the rich, yeast maintenance agar medium, YPDA, at 37°C. Additionally, deletion of WdSTUA repressed aerial hyphal growth, conidiation and invasive hyphal growth on the nitrogen poor, hyphae-inducing agar medium, PDA, at 25°C. Ectopic expression of WdSTU Arepressed the convoluted colony surface growth on YPDA at 37°C, and also strongly repressed hyphal growth on PDA at 25°C and 37°C. Expression of WdSTUA in S. cerevisiae induced pseudohyphal growth on the nitrogen poor medium. WdPacCp was also most similar to the PacCp proteins of Aspergillus species. Three zinc finger DNA-binding motifs were at the N-terminus, and the C-terminus had the signaling protease cleavage site. WdPACC was more expressed at neutral-alkaline pH than at acidic pH. Truncation of the coding sequence for about 40 residues upstream of the conserved processing protease cleavage site of WdPacCp affected growth on YPDA, increased sensitivity to Na⁺ stress, decreased growth level at neutral-alkaline pH, and repressed hyphal growth on PDA at 25°C. Truncation of the coding sequence for the conserved signaling protease box of WdPacCp impaired growth and reduced RNA expression of class II chitin synthase gene WdCHS1 at acidic pH, and activated hyphal growth on PDA. My results suggested that WdStuAp and WdPacCp play important roles in yeast-hyphal transitions in W. dermatitidis, and that WdPacCp is particularly important for W. dermatitidis to adapt to different ambient pH conditions.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.