Probably no group of organisms has been as important as bacteriophages when it comes to the understanding of fundamental biological processes like transcriptional control, DNA replication, site-specific recombination, e.t.c. The work presented in this thesis is a contribution towards the complete understanding of these organisms. Two proteins, integrase, and Cox, which are important for the choice of the life mode of bacteriophage P2, are investigated. P2 is a temperate phage, i.e. it can either insert its DNA into the host chromosome (by site-specific recombination) and wait (lysogeny), or it can produce new progeny with the help of the host protein machinery and thereafter lyse the cell (lytic cycle). The integrase protein is necessary for the integration and excision of the phage genome. The Cox protein is involved as a directional factor in the site-specific recombination, where it stimulates excision and inhibits integration. It has been shown that the Cox protein also is important for the choice of the lytic cycle. The choice of life mode is regulated on a transcriptional level, where two mutually exclusive promoters direct whether the lytic cycle (Pe) or lysogeny (Pc) is chosen. The Cox pro-tein has been shown to repress the Pc promoter and thereby making tran-scription from the Pe promoter possible, leading to the lytic cycle. Further, the Cox protein can function as a transcriptional activator on the parasite phage, P4. P4 has gained the ability to adopt the P2 protein machinery to its own purposes. In this work the importance of the native size for biologically active integrase and Cox proteins has been determined. Further, structure-function analyses of the two proteins have been performed with focus on the protein-protein interfaces. In addition it is shown that P2 Cox and the P2 relative Wphi Cox changes the DNA topology upon specific binding. From the obtained results a mechanism for P2 Cox-DNA interaction is discussed. The results from this thesis can be used in the development of a gene delivery system based on the P2 site-specific recombination system.

Thesis (Ph. D.)--University of Missouri--Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 108-125). Also available on the Internet.

Thesis (Ph. D.)--Case Western Reserve University, 2004. / [School of Medicine] Department of Pathology. Includes bibliographical references. Available online via OhioLINK's ETD Center.

No description available.

This thesis is a reconnaissance of the behavioural ecology of domestic cats. The principal subjects were two groups of farm cats. There was also a group of captive cats and a house cat. The study differs from all previous ones in that the cats were tame and therefore could be shadowed and observed for long periods at all hours. It deals with (1) activity patterns and activity budget, (2) use of space and social behaviour, (3) scent communication, (4) foraging and (5) population dynamics.

Diss. (sammanfattning) Stockholm : Univ., 2005. / Härtill 3 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Stockholms universitet, 2007. / Härtill 3 uppsatser.

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / "July 1998." Typescript. Vita. Includes bibliographical references (leaves 145-165). Also available on the Internet.

Listeria monocytogenes is a Gram-positive facultative intracellular bacterium with a wide ecological niche and causes a number of diseases in human and animals. It invades mammalian host cells and escapes from the vacuoles prior to replication in the host cell cytoplasm and infecting adjacent cells via actin-based mobility. Phosphoinositide (PIP) metabolism is essential to mammalian cells in signal transduction, actin remodelling, endosome dynamics and membrane trafficking. Modulation of host PIP metabolism by bacteria PIP phosphatases is important for pathogenicity and virulence of many human pathogens. In this study the function of two L. monocytogenes tyrosine and inositol phosphatases LipA and LipB were studied in vitro. The lipA and lipB deletion mutants generated in EGDe and InlA strains were not affected in invasion but were attenuated in intracellular growth in Caco-2 and Hela M cell lines but not in mouse macrophages. Deletion of lipA or lipB did not affect the actin polymerisation but caused reduced plaque number in the plaque assay. The turnover of five PIPs in Hela M cells during L. monocytogenes infection were studied by expression of fluorescent protein tagged domains that specifically recognizes individual PIPs. L. monocytognenes did not affect the metabolism of PI4P, PI(4,5)P2, PI(3,4,5)P3 but co-localised with PI3P at 1.5 hr post-infection and with PI(3,4)P2 at 6 hr to 24 hr post-infection. The PI(3,4)P2 effector protein lamellipodin was discovered to be recruited to actin-associated L. monocytogenes at 4 hr to 24 hr post-infection in Hela M cells. This discovery leads to the hypothesis of a novel mechanism of lamellipodin-dependant cell-to-cell spread. The lipA mutant was found to be attenuated in PI(3,4)P2 recruitment and therefore hypothesized to participate in the proposed lamellipodin pathway by converting PI(3,5)P2 into PI5P, leading to the activation of PI3K and subsequent production of PI(3,4)P2. LipB showed partial localisation at the Golgi complex when over-expressed in Hela M cells, and it was assumed to act mainly as a protein-tyrosine phosphatase. In summary, this study provides some evidence on L. monocytogenes modulating host PIP metabolism by the production of inositol phosphatases. It gives us a better understanding on the intracellular growth of this pathogenic bacterium, and on the interaction between host and parasite.