The archaeal flagellum is a unique motility structure. Although functionally similar to the bacterial flagellum, the archaeal flagellum shares more similarities to the bacterial type IV pilus. Using the methanogenic archaea Methanococcus voltae and Methanococcus maripaludis as model organisms, the structural and post-translational requirements for flagellation have been investigated. Known to contain glycosylated flagellin proteins, the N-glycosylation pathway was studied in M. voltae. A number of possible glycosylation component genes, including glycosyl transferases, flippases and an oligosaccharyl transferase were inactivated or deleted in M. voltae and their resulting phenotypes were characterized. Four glycosyl transferases were identified as involved in the assembly of the M. voltae glycan structure, with three of these enzymes, AglA, AglC1 and AglC2, experimentally verified. As well, the oligosaccharyl transferase, AglB, has also been experimentally confirmed and was found to be the homolog of the bacterial and eukaryotic equivalents, PglB and Stt3p, respectively. Disruption of glycan synthesis or attachment resulted in very poorly or non-flagellated cells, implicating for the first time that the glycan structure on archaeal flagellins is necessary for proper flagella assembly and/or stability. These findings also represent the first proven N-glycosylation genes within the domain Archaea. New markerless, in-frame deletion methodology has allowed for advanced studies of a demonstrated and putative set of flagella-related genes in M. maripaludis. This collection of 11 co-transcribed genes, consisting of three flagellin genes (flaB1-flaB3), six genes of unknown function (flaC-flaH) and two genes implicated in flagellin subunit export (flaI and flaJ), make up the fla operon in this organism. Each gene from flaB1-flaI was systematically targeted for deletion and complementation to determine its necessity for flagellation. The analysis showed that both major flagellins, FlaB1 and FlaB2 are required for flagellation, while the minor flagellin, FlaB3, was required for the hook-like region of the flagella filament. FlaC, FlaF, FlaG and FlaH were shown for the first time to be essential for flagellation, while a naturally-occurring, truncated version of FlaD was found not to be required. These results continue to develop our understanding of the archaeal flagellum and the components necessary for its assembly and/or structure. / Thesis (Ph.D, Microbiology & Immunology) -- Queen's University, 2007-07-11 16:50:37.119

Cette thèse étudie, à partir d’un corpus d’environ 950 images, l’iconographie du Procès du Christ dans la culture italienne de la fin du Moyen Âge. Elle est le fruit d’une double ambition : celle de retracer l’évolution iconographique des scènes (Comparutions devant les juges, Outrages, Couronnement d’épines, Flagellation) et du cycle dans son ensemble, et ce, dès les premiers siècles de l’art chrétien, mais au-delà, celle de replacer ces images d’injustice dans le champ spirituel, culturel, judiciaire et politique d’une société profondément imprégné d’une pluralité de discours sur la justice. La première partie remonte aux sources, textuelles et visuelles, afin de mieux comprendre l’élaboration progressive du cycle visuel et de mieux cerner l’inventivité des solutions italiennes à partir de la seconde moitié du XIIIe siècle. La deuxième partie est une exploration d’un corpus de 950 images. L’analyse des évolutions iconographiques scène après scène est enrichie par une analyse sémantique. Il s’agit en effet de montrer comment sont figurés à la fois une justice dysfonctionnelle et le paradoxe du Christus iudicatus, en regard notamment des images contemporaines de la justice. La dernière partie est une réflexion sur les diverses modalités de mise en acte de ces images, selon les supports et les contextes, dévotionnels, judiciaires, mais également politique. Cet éclairage multiple confère à ce thème iconographique une profondeur et une résonance particulière. Dans une société pénétrée par le thème de la justice, à la fois institution en quête d’elle-même, vertu chrétienne et puissance divine, il fait office d’un repoussoir rhétorique efficace, tout en étant chargé d’une forte ambivalence propre à la culture médiévale.Mots clés : apparatus visuel, Arena, Aula épiscopales de Bergame, Ben Comune, Caïphe, Pietro Cavallini, Christ, Comune rubato, conforto, Couronnement d’épines, croix peinte, dévotion, Diligite iustitiam, discipline Duccio, fama, Flagellation, Florence, fresque, Giotto, Giustizia bendata, Hérode, imitatio Christi, infamia, injustice, Jugement dernier, juifs, justice, Lavement des mains, Pietro Lorenzetti, Maestà, Meditationes Vitae Christi, memento falliri, memoria, métalepse visuelle, Passion, Pilate, Présentation au peuple, procès, retable, Rhetorica ad Herennium, rituels, rituels judiciaires, Sienne, spiritualité mendiante, tavoletta, vertu, vice / This dissertation examines, from a corpus of about 950 images, the various scenes of the Trial of Christ in the late medieval Italian culture. It claims two aims. Firstly, it draws the iconographic evolution of each scene (Christ before his judges, Mocking, Crowning of Thorns, Flagellation) and of the entire sequence, from the first centuries of Christian art ; secondly, it inserts theses images of injustice in the spiritual, cultural, judicial and political context of a society which is profoundly pervaded by the theme of justice. The first section deals with the textual and visual sources in order to examine the elaboration of the sequence and the inventiveness of the Italian solutions since the second half of the XIIIth century. The second section is a survey of the corpus, lead by a geographico-historical analysis of the production of these images. This aspect is extended by a semantic approach of these scenes picturing the injustice and the infamia endured by the Son of God, notably through the light of the increasing corpus of images of institutional justice. The last section examines the question of the efficacity of these images in various contexts (devotion, judicial rituals, civic rhetoric, politics). Thanks to that diversity of approaches, the theme of the Trial of Jesus reveals profound resonances in the web of Italian societies, where justice is an institution in search of its own identity, a Christian virtue and the privilege of God at End Time. Its acts notably as a powerful but ambivalent rhetorical counterexample.Key words : agency of image, altarpiece, visual apparatus, Arena, episcopal aula of Bergamo, Ben Comune, Blind Justice, Caiaphas, Pietro Cavallini, Christ, Comune rubato, conforto, Crowning of Thorns, devotion, Diligite iustisiam, discipline, Duccio, Ecce Homo, efficace des images, fama, Flagellation, Florence, frescoes, Giotto, Herode, imitatio Christi, infamia, injustice, Jews, Last Judgment, justice, Pietro Lorenzetti, Maestà, Meditationes Vitae Christi, memento falliri, memoria, visual metalepsis, painted cross, Passion, Pilate, Pilate washing his hands, Rhetorica ad Herennium, rituals, judicial rituals, Siena, mendicant spirituality, tavoletta, trial, vice, virtue.

Imagine a theater. Build one in your mind. I do not care if it is the largest theater in the universe or if it is the size of a shoebox. The theater can be an elaborate construction with gilded cherubs and priceless jewels. If you would prefer the theater to be a minimal design, imagine it that way. Maybe the theater is made out of glass or crystal. You can be all alone in the theater or maybe you are seated next to an alien, a cave man, or a robot. As the curtain rises an enormous pipe organ is spewing out J.S. Bach’s Toccata and Fugue in D minor. The sound is colossal. The stage is designed to look like a filthy and bleak art studio. Sculptures that look like decaying flesh hang from the ceiling. Papers and dirty painting rags are scattered all over the floor. A roach crawls towards some moldy food in the wastebasket. A piece of beef jerky sits next to a pile of paint tubes and paintbrushes. Canvases are stacked against the wall. Dried paint is splattered everywhere. A woman enters stage left. As she begins to speak, the music fades… “My most recent paintings are meant to serve as gateways between daily life and an exotic utopian fantasy. These strange psychological spaces function as portals into a new frontier inhabited with the most stupendous creatures. Active volcanoes, carnivorous plants, terrible lizards, pink Chihuahuas, flesh-eating insects, unidentified flying objects, and a host of other amazing things coexist in this cruel tropical paradise. “Everything I do is a self-portrait and a disguise. I imagine the characters in my paintings to be mutant clones. The act of painting is like looking in the mirror. I like to spend most of my time doing one or the other. I am driven by an insatiable urge to see what I truly look like. I suffer from an unfulfilled desire to meet myself. I am frustrated with impressions and reflections. These confessions reveal my work as possibly the most disgusting display of narcissism in the entire history of art. “The act of painting is an absurd and self-indulgent enterprise. I paint with the ridiculous and frivolous purpose of delighting the eye. Nevertheless, my hope is that my paintings capture an important aspect of my utopian fantasy with their sumptuous surroundings embellished with rainbows, natural disasters, butterflies, exotic grasses and bizarre costumes. “My paintings can be read on many different levels from surface to deep allegory. The finished product is the result of hours upon hours of painting, pondering, and dreaming. Below the surface lies a nauseating abyss. “My work is a delicious feast for the aesthetic consumer. I am a villainous mad scientist with a hunger for immortality. My eyes are gluttonous fools. I am a mystery and a deception. Vermillion is my opulent fetish. Lemon yellow is my nemesis.” The music grows louder again. The woman begins to cackle. She then takes a deep breath and a deeper and more dramatic bow. She exits stage right--you find that you want to applaud--but unfortunately, this story is not over. I suggest that you get yourself a snack like some popcorn, chocolate, or gummy bears before reading any further. The curtain slowly and elegantly comes down.

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