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No description available.

This thesis presents results obtained from the investigation of secondary metabolites through screening of marine organisms, marine-derived microbes, and microbes form under-explored habitats. The first part includes the isolation of eight cytotoxic diterpene derivatives of which four were new from the organic extract of the sponge <i>Spongionella </i>sp. obtained from the U.S. National Cancer Institute’s Open Repository Program, the isolation of three new antibacterial dibenzofuran derivatives and a known butyrolactone from ascomycete Super1F1-09 isolated from the Indo-Pacific sponge <i>Acanthella cavernosa. </i>An attempt to synthesize these compounds was conducted. This part also includes the isolation of five known pyrroloiminoquinone alkaloids, from the Fijian sponge <i>Zyzzya</i> sp., which showed potent antiprotozoal activity. The second part comprises the use of OSMAC approach for the isolation of four new ansamycin-type polyketides, three new macrolactones and one known siderophore from <i>Streptomyces </i>strain C34 isolated from Atacama Desert, Chile. These compounds showed good antibacterial activity with one of the ansamycins showed pronounced antibacterial activity against a panel of clinical isolates of methicillin-sensitive as well as methicillin-resistant <i>S. aureus</i> (MRSA). This part also contains the use of microbial co-culture for the induction of secondary metabolites. It comprises the isolation of ten antiprotozoal fungal metabolites, of which one was new, from <i>Aspergillus fumigatus </i>when co-cultured with the novel strain <i>Streptomyces </i>C2 isolated from Atacama Desert. In conclusion, natural products from diverse sources proved to be the major resource of drug discovery. This thesis describes the isolation and structural characterisation of 35 compounds, 15 of which were new. Extremophiles proved to be a good source for new secondary metabolites.

Here I present results from three field studies and one manipulative experiment that explored some of the factors that may influence belowground communities at multiple spatial scales. In the first field study I found that the abundance of two groups of soil mites was positively related to soil pore volume in two contrasting habitats. Hence, by limiting abundance, soil pore volume could indirectly influence species richness of mites. In another field study, using a spatial design, I found that the variation in community composition of soil mites and microbes within habitats was related to the variation in soil properties and plant community composition. However, the relative influence of these factors depended on the degree to which they varied within a habitat. Similarly, using a multi-site field study I found that soil properties, plant community composition and also precipitation influenced the composition of the microbial and mite communities within the landscape. This study also showed that the species richness of soil mites within a site was related to the degree of variation in soil properties and vegetation within the site. Finally, a manipulative field experiment showed that species richness of soil fauna was related to small-scale heterogeneity in soil physical properties, and that both the abundance and composition of belowground communities was related to the organic horizon thickness. Overall, my work shows a general positive relationship between species richness of soil biota and heterogeneity across spatial scales, and that the composition of belowground communities is related to the variation in soil properties, plant community composition and climate.

This study was designed to show what dissemules may be carried by selected genera of Odonata, where the dissemules may be predominantly carried on the selected insects and to relate the behavior of the selected Odonata to frequency of occurrence of micro-organisms on the insects.

Thesis (doctoral)--Göteborg University, 2006. / Includes bibliographical references.

Univ., Diss.--Göteborg, 2006. / Enth. außerdem 5 Zeitschriftenaufsätze.

No description available.

No description available.

Thesis (M.S.)--Naval Postgraduate School, 1966. / Thesis advisor(s): Haderlie, Eugene C. Cover title. "October 1966." Includes bibliographical references (p. 48-50).