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Thesis (Ph. D.)--University of Wisconsin--Madison, 1939. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 87).

Thesis (M.S.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (doctoral)--Universität Marburg, 1931. / "Lebenslauf." Includes bibliographical references (p. 40-44).

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. [97]-109.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 18 (1958) no. 3, p. 766. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 33-35).

The potential of the filamentous fungus Aspergillus fumigatus to act as an opportunistic pathogen may be related to its ability to resist the host defence network. Whilst phagocytic cells are clearly important in host defences against invading microorganisms their precise role in the killing of A. fumigatus remains undefined. The purpose of this study was to examine the basic interactions between phagocytic cells, from humans and rodents, with spores of A. fumigatus. In particular the mechanisms whereby phagocytic cells bind and kill spores of A. fumigatus, when compared with the relatively non-pathogenic fungus Penicillium ochrochloron were investigated. In order to investigate why people with asthma may develop some hypersensitivity reactions to A. fumigatus, in particular, rather than to the many other fungi in the atmosphere, the possibility that there may be a defect in the handling of the fungus by such patients has been tested. A comparison of the fungal handling by phagocytes from asthmatic patients, both sensitised and unsensitised to A. fumigatus with phagocytes from non-asthmatic subjects has been made. The principal findings from this study are that spores of A. fumigatus bind to the surface of the phagocytic cell yet are relatively resistant to phagocytosis. The spores also fail to trigger the phagocytic cells into releasing the potentially microbicidal reactive oxygen intermediates. These results may be related to a further finding which is that spores of A. fumigatus release a low molecular weight substance (diffusate) which interferes with various aspects of phagocytic cell activation. Spore diffusates were shown to inhibit the phagocytosis of radiolabelled antibody-coated sheep red blood cells and to suppress the spontaneous release of reactive oxygen intermediates by Corynebacterium parvum stimulated mouse peritoneal exudate cells. In addition spores diffusates inhibited the ability of phagocytic cells to spread on glass and reduce the number of phagocytic cells migrating towards a known chemoattractant. Studies on spore killing showed that spores of A. fumigatus opsonised in autologous serum were more resistant to killing by phagocytic cells from humans and rodents than similarly opsonised spores of P. ochrochloron. However, the ability of the phagocytic cells to kill spores of A. fumigatus was substantially increased when the spores were opsonised in sera which had been heat-treated for 30 minutes at 56?C. No increased killing was found with P. ochrochloron. People with asthma sensitised to A. fumigatus showed significant differences in their handling of A. fumigatus in vitro when compared with the control group. Monocytes from these sensitised patients killed significantly fewer spores of A. fumigatus (opsonised in auto? logous sera) whilst their polymorphonuclear leucocytes killed significantly more. No such differences were found for P. ochrochloron. The work reported in this Thesis has given us a clearer understanding of why Aspergillus fumigatus is an important cause of disease in man, and how the defence mechanisms that it has evolved in its natural environment the soil, enable it to act as a saprophyte or parasite in the lungs of humans and animals. The results also suggest a mechanism whereby heat-labile serum components may be an advantage to the survival of the fungus, thus perhaps explaining why it may be a particular problem in the airways of asthmatic patients.

M.Sc. / The remarkable adaptability of the ruminant with respect to the variety of feeds of different composition which it can utilize is attributable to the presence, in the rumen, of a complex microbial population with diverse nutritional requirements and enzymatic activities. For economic reasons it is essential in feedlot practice to meet, as closely as possible, the energy requirements of ruminants being rounded off for slaughter purposes. This necessitates adapting the animals in the shortest possible time from predominantly pasture to high-concentrate diets, i.e. diets containing a high proportion of readily fermentable carbohydrates. However, a very rapid transition between these diets frequently results in a perturbation of the microbial population of the rumen. In particular, the sudden increase in the concentration of readily fermentable carbohydrates favours the proliferation of lactic acid-producing species, whereas the numbers of lactic acid-utilizing species increase more slowly. The resulting accumulation of lactic acid in the rumen causes a marked drop in pH which has an adverse effect on digestive processes in general. In mild cases, this may merely have a temporary negative effect on food intake and growth of the animal, but in the worst cases it may lead to ruminal stasis, cause permanent damage to the lining of the rumen wall and even result in death. Even though the incidence and severity of acute lactic acidosis may be restricted through careful diet formulation and inclusion of buffers and ionophore antibiotics in the diet, a small proportion of the animals brought into feedlots do not adapt readily to the highconcentrate diets and the performance of a larger proportion is probably negatively affected by sub-acute acidosis. The Nutritional Microbiology Section of the ARC Animal Nutrition and Animal Products Institute at Irene therefore embarked on the development of an alternative preventative and therapeutic treatment against lactic acidosis, viz. the administration of live, laboratory-grown cultures of highly-active lactate utilizers, specially selected for their potential for survival and multiplication in the rumen of animals on feedlot diets. By selective enrichment and extensive screening procedures a collection of phenotypically similar isolates of anaerobic, large, Gram-negative, acid-tolerant and ionophore-resistant cocci was obtained, which were presumptively identified as strains of Megasphaera elsdenii. These organisms utilized both L(+) and D(-) lactate and showed high specific growth rates on relatively inexpensive media even at low pH values, and they appeared to hold good promise for the intended application. In order to test the effectiveness of treatment of acidosis-compromised animals with cultures of these bacteria, information on their persistence in the rumen was required. Conventional microbiological counting methods were unsuitable for this purpose because of slowness and unsatisfactory specificity and precision. The present investigation deals primarily with the design and evaluation of a speciesspecific 16S rRNA probe for M elsdenii. It was intended for following the contribution of this species to the total microbial population of the rumen, as affected by the sudden exposure to high-concentrate diets. Furthermore, the phylogenetic relationship between the recent isolates, the type strain and previously sequenced strains of M elsdenii and M cerevisiae, as well as representatives of other rumen bacteria was investigated. In conclusion, the method for measuring the relative abundance of M elsdenii in rumen microbial populations with the aid of a custom-designed rRNA probe satisfactorily met the requirements of the proposed application.

A cytological study of sporogenesis, mature uredospores and hydrated uredospores of Puccinia graminis tritici was made to determine if a definitive nucleolus was present. Electron microscopy has shown that the nuclei in immature uredospores and associated fungal tissue of the uredosorus possess prominent nucleoli. Nucleoli whose average diameter was 1.7 microns were observed in 58 percent of the nuclear sections from immature uredospores. Presence of a nucleolus in ultrathin sections of mature uredospores is established. Nucleoli whose average diameter was 0.5 microns were observed in 6 percent of the nuclear sections from mature uredospores. Nucleoli were not observed in hydrated uredospores which had resumed active metabolism. The reduction in the size of the nucleoli in mature uredospores and absence of nucleoli in hydrated uredospores may indicate that ribosomal RNA synthesis is repressed as uredospores mature. / Land and Food Systems, Faculty of / Graduate