Many illnesses and infections are exacerbated and/or caused by biofilms. Neisseria gonorrhoeae, the etiologic agent of gonorrhea, is frequently asymptomatic in women, which can lead to persistent infection. Persistent infection can result in pelvic inflammatory disease, tubo-ovarian abscesses, infertility, and ectopic pregnancy. N. gonorrhoeae has been shown to form biofilms over glass, primary and immortalized cervical cells, and during natural cervical infection. Asymptomatic infection occurs in only 1% of infected males, and the infection site is subject to periodic rapid fluid flow, which may limit biofilm formation. Thus, biofilm formation may specifically play an important role in the infection of women and could contribute to the infrequent occurrence of symptoms. Prior to work presented in this dissertation, little was known about biofilm formation by N. gonorrhoeae. Therefore, we elected to compare the transcriptional profiles of biofilms to their planktonic counterparts, to identify genetic pathways involved in biofilm formation and maintenance. We found that 3.8% of the genome was differentially regulated, and that genes involved in anaerobic metabolism and oxidative stress tolerance were up-regulated in biofilm, while genes involved in aerobic metabolism were down-regulated. We determined that expression of aniA , ccp, and norB is required for robust biofilm formation over glass and human cervical cells, and anaerobic respiration occurs in the substratum of gonococcal biofilms. Disruption of the norB gene resulted in severe attenuation of biofilm formation. We determined that the accumulation of nitric oxide (NO) contributes to the phenotype of a norB mutant and can retard biofilm formation when present at sublethal concentrations. However, higher concentrations of NO can enhance biofilm formation in the absence of nitrite. NO enhances biofilm formation in an aniA mutant, but cannot completely restore biofilm formation, suggesting that NO can support anaerobic growth, although nitrite is preferred. We determined that the majority of the genes involved in gonococcal oxidative stress tolerance are required for normal biofilm formation, as mutations in the following genes resulted in biofilm attenuation over cervical cells and/or glass: oxyR, gor, prx, mntABC, trxB, and estD. Overall, biofilm formation may represent an adaptation for coping with the stresses present in the female genitourinary tract.

Neisseria meningitidis is the causative agent of potentially life-threatening meningitis and septicaemia. According to W.H.O., meningococcal disease causes at least 500,000 cases and results in 50,000 deaths worldwide each year (W.H.O., 2008). Neisseria gonorrhoeae is causing the second most common sexually transmitted bacterial infection, with a global incidence of 62 million cases per year. Previous studies have shown surface expressed proteins like pilin, the subunit protein that forms pili (Type IV Fimbriae), in N. meningitidis and N. gonorrhoeae are post-translationally modified by O-glycosylation. This modification has been proposed to be of importance in the pathogenesis of these species. Although the exact function of these post-translational modifications are not fully understood, it is suggested that these modification have a role for immune evasion in the host. In this thesis, an additional outer membrane glycoprotein was identified in pathogenic Neisseria, the nitrite reductase AniA. Mass spectrometry analysis showed that AniA is glycosylated in its C-terminal imperfect (AASAP) repeat region by the pilin glycosylation pathway. This is the first report of a general O-glycosylation pathway in a prokaryote. It was shown AniA is surface exposed. To investigate whether AniA is subject to immune selection, a large collection of N. meningitidis and N. meningitidis clinical isolates were sequence analysed and evaluated. Analysis of published AniA 3D structure revealed that AniA displayed polymorphisms in residues that map to the surface of the protein. This suggests that AniA is under immune selection, and that glycosylation may facilitate immune evasion. Sequencing analyses revealed a frame shift mutation that abolished AniA expression in 34% of N. meningitidis strains surveyed. However, all N. gonorrhoeae strains examined are predicted to express AniA, implying a crucial role for AniA in gonococcal biology. In summary, the data presented here suggested that the protein may be under immune selective pressure. The addition of a phase variable glycan to this surface protein may serve as an additional immune evasion strategy. Immune selection on surface proteins in these host-adapted pathogens may have been the driving force for the evolution of this general O-glycosylation pathway. Therefore, the discovery that AniA is a glycoprotein has given insights into the pathogenesis and the host-pathogen interactions of these organisms.

Thesis (PhD)--Macquarie University, Division of Humanities, Department of English, 2005. / "March 2002". Bibliography: p. 324-344.

"March 2002". / Thesis (PhD)--Macquarie University, Division of Humanities, Department of English, 2005. / Bibliography: p. 324-344. / Introduction: framing the texts -- Subversive voices -- Formulating a theoretical position -- Performance: a complete process -- On second thoughts: rewriting contemporary culture -- Performing On second thoghts -- Dialogic voices: Amanda Stewart and # -- Performing # -- Voices of desire: Ania Walwicz and Soft -- Performing Soft -- Marginal voices: Hazel Smith and Poet without language -- Performing Poet without language -- Conclusions: interpreting subversive voices. / This study considers the text and performance of four Australian experimental poets, Chris Mann, Amanda Stewart, Ania Walwicz and Hazel Smith. My aim is to demonstrate how the genre of experimental poetry uses language and performance in such a way as to rewrite existing dominant discourses. The challenge as an analyst is to find ways into such reflexive texts that use intertextual resources of critical theory as their subject matter. The perspective employed here engages with the theories posited by the texts and allows for a theoretical position removed from the structure and theories informing them. -- The study is organised in two parts. First, I consider the subversiveness of the genre drawing on Raymond Williams' notion of the emergent, followed by a discussion of important predecessors in the field of experimentation. I then outline the particular method of enquiry and theoretical framework used here to analyse the meaning potential of such works. Systemic Functional Grammar and Multimodal Discourse theory are discussed and their particular application in this study. The second part of the thesis applies these theories to the experimental works. -- I begin explaining my theoretical position by considering the weakness of the commonly used theories of Kristeva's 'semiotic' to analyse such works. I found Systemic Functional Grammar, as developed by Michael Halliday and then Terry Threadgold, to be a useful tool for elucidating the meaning potential behind the fractured grammars in the texts. It also provided a way of conceptualising enunciative positions and the way intertextual resources might be rewritten. From within this linguistic framework I was able to discern subversive messages from the intertwined theories ranging across the texts from Marxism, structuralism, psychoanalysis, feminism and multiculturalism. -- The performance posed another challenge as the improvised spoken texts, uniquely performed by these artists, create a subversive listening position for the audience, which engages with both the words and sounds for their sonic and semantic qualities. I consider many ways of addressing the role and behaviour of the performer and listener as well as the performance as a creative process, emerging from the two. I engage the model put forward by Kress and Van Leeuwen for analysis of multimodal texts which provides a functional approach to meaning potential in the performance and its varying layers. Within this model, I found prosody most useful for its ability to notate intonation, key, disjuncture and stress, exposing the dialogic voices and the relationship between semantics and sound in the performances. This form of communication is equivalent to the indexical entailment of sound and music which forms the basis for communication between performers, and between performer and audience. The dialogic situation is enhanced by both prosody and indexical entailment providing possible meanings. I use some traditional musicological analysis but my aim is to move away from such formalistic descriptions to consider culturally inscribed sounds and their interpretation using a functional model. -- Throughout, the complexity of experimental performance is evident but the theoretical frame used here might be applied to other works of this nature as a means of further understanding the semiotic web in subversive texts. / Mode of access: World Wide Web. / 344 p., music