Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 107-118). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Chicago, Dept. of Molecular Genetics and Cell Biology, March 2000. / Includes bibliographical references. Also available on the Internet.

Thesis (M.Sc.) -- Memorial University of Newfoundland. 1976. / Typescript. Bibliography : leaves 137-148. Also available online.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The basidiomycetous yeast Malassezia has been linked to a number of disease states such as seborrhoeic dermatitis, dandruff and pityriasis versicolor. Much confusion has arisen as to its role in these disease states as this fungus is found inhabiting the stratum corneum of approximately 90% of the human adult population. Malassezia yeasts are lipophilic organisms, some species showing a specific requirement for long chain fatty acids for in vitro culture. The object of the experiments undertaken in this study was to elucidate the role of Malassezia yeasts in dandruff and seborrhoeic dermatitis.

The Neotropical cloud forest inhabiting orchid Dracula felix has long been postulated to be a fungal mimic due to the form of its lower labellum and attraction to it by drosophilid flies that are often found feeding on fungal fruiting bodies in the surrounding area. The low number of co-occurring flowers in the area combined with the high number of fruiting fungi appears to have driven the evolution of the orchid genus Dracula to mimic these co-occurring fungi so that pollinators may be recruited. Over several years of working with these orchids we have noticed a particular lapping behavior by the pollinating flies on the labella and sepals of the Dracula flowers. In this study we have first surveyed floral yeasts and molds associated with Dracula flowers and then investigated the role of these fungi in attracting pollinators and offering a food reward to retain them for pollination purposes. In addition to the floral yeasts, leaf endophytes and root associated fungi were cultured and identified, and their frequencies were determined.

No description available.

Strains of the budding-yeast Kluyveromyces lactis that produce killer-toxin contain two linear dsDNA plasmids, kl (8.9 Kb) and (13.4 Kb). The genes of kl are preceded by no known gene expression signals and transcripts are probably not polyadenylated. Classical and molecular genetic techniques have been used to attempt to investigate the mechanisms of replication, partitioning and gene expression utilised by these novel elements. Such studies have led to the preparation of a number of vectors and strains of use in this and other analyses. Data or presented which indicate the killer plasmids exist within the cytoplasm of the yeast cell, and probably do not require the nuclear RNA polymerases I, II or III for transcription of their genes. A preparation procedure has been developed for the linear plasmids, and plasmid k2, thought to encode factors necessary for the maintenance or expression of k1, has been cloned. Sequence analysis of 7,7 kb of plasmid k2 revealed the presence of several open reading frames (ORFs) organised in a similar manner to those of plasmid k1. One of these is predicted to encode a product with homology to two different subunits found within several DNA-directed RNA polymerases. Another ORF potentially encodes a polypeptide with homology to a DNA helicase encoded by, and required for accurate transcription of, the cytoplasmic poxvirus vaccinia. These two k2 products may be components of a killer plasmid-specific cytoplasmic gene expression system. Possible mechanisms of killer plasmid replication, partitioning and gene expression are discussed.

M. Tech. / Yeast such as Candida albicans are the major cause of human diseases such as genital thrush and oral thrush. Some of the genital isolates of C. albicans that were studied by Shah et al. (1991 & 1995) were found to produce the medically important immunosuppressing mycotoxin gliotoxin, which has potential important medical consequences. The biosynthesis of this mycotoxin is regulated and expressed by the presence of the gliP and gliZ genes, which were identified on the putative gene cluster of A. fumigatus. Most Candidal infections are treated using a single or a combination of antifungal agents such as amphotericin B (AmB), fluconazole, flucytosine, voriconazole, caspofungin, itraconazole, posaconazole and ketoconazole. The mode of action for these antifungal agents differs in terms of what molecule or processes are inhibited. The details of each antifungal agent and its mode of action are discussed in chapter 6 (page 54). These antifungal agents are usually recommended for the treatment of candidosis and currently the most common Candida spp. have developed resistance to these antifungal agents. The identification of Candida isolates was done using 2 different types of identification methods i.e., the chromogenic medium CHROMagar Candida and the biochemical test kit API 10 Candida. The chromogenic medium was inoculated with the Candida spp. supplied and incubated for 3 days at 37oC. The API 10C test strips were loaded with the culture suspension and incubated for 24 hours at 37oC. For the screening of gliotoxin, 2 supplemented mediums were used to cultivate the isolates that is the yeast extract sucrose (YES) and Eagles minimal essential medium (EMEM) and the isolates were grown at 37oC for 72 days. The methods that were used to identify the gliotoxin were thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) to quantify the levels of gliotoxin.

No description available.