x, 153, xxviii leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology, 1975

x, 153, xxviii leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology, 1975

Diss. (sammanfattning) Stockholm : Univ., 2007. / Härtill 4 uppsatser.

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

Thesis (Ph.D.) -- University of Adelaide, Dept. of Microbiology, 1975.

Thesis (Ph. D.)--University of Oregon, 2004. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 163-172). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 160-180). Also available on the World Wide Web.

A relação entre bacteriófagos e virulência bacteriana é um modelo muito intrigante e pouco estudado na patogênese periodontal, uma vez que um patógeno periodontal pode ser lisogênico. O objetivo do nosso estudo é determinar a capacidade de fibroblastos gengivais humanos de induzir as cepas lisogênicas de Aggregatibacter actinomycetemcomitans. Dois experimentos foram realizados seguidos da titulação de fago. Os experimentos consistiram da co-cultura com fibroblastos gengivais humanos e três cepas de Aa [Aa29524, Aa2112, Aa29524(Ø2112)], não lisogênica, lisogênica e lisogênica induzida em laboratório, respectivamente. Em três momentos distintos (no experimento 1: 0, 2 e 4 horas; e no experimento 2: 2, 4 e 6 horas), o sobrenadante da co-cultura foi filtrado e cultivado overnight com a bactéria indicadora (Aa29524) e analisado para a capacidade de lisar a célula indicadora. Em ambos os experimentos, o sobrenadante da co-cultura de fibroblastos gengivais humanos com Aa lisogênico e Aa lisogênico induzido em laboratório, ao ser cultivado com a bactéria indicadora, promoveu lise da mesma, resultando no aumento da produção de fago. Pode-se concluir que, nesse estudo os fibroblastos gengivais humanos foram capazes de induzir cepas lisogênicas de Aggregatibacter actinomycetemcomitans. / The relationship between bacteriophages and bacterial virulence is a very intriguing, but rarely studied model in periodontal pathogenesis, as a periodontal pathogens can be lysogenic. The aim of our study is to determine the ability of human gingival fibroblasts to induce lysogenic strains of Aggregatibacter actinomycetemcomitans. Two experiments were performed followed by titration of phage. The experiments consisted of co-culture with human gingival fibroblasts and three strains of Aa [Aa29524, Aa2112, Aa29524 (Ø2112)], not lysogenic, lysogenic and lysogenic induced in the laboratory, respectively. In three different times (in experiment 1: 0, 2 and 4 hours, and in experiment 2: 2, 4 and 6 hours), the co-culture supernatant was filtered and cultured overnight with the indicator strain (Aa29524) and analyzed for ability to lyse the cell indicator. In both experiments, the supernatant of the co-culture of human gingival fibroblasts with Aa lysogenic and Aa lysogenic induced in the laboratory to be cultured with the indicator bacteria, caused lysis of the same, resulting an increased phage production. It can be concluded that in this study, human gingival fibroblasts were able to induce lysogenic strains of Aggregatibacter actinomycetemcomitans.

The superinfection exclusion gene (sieB) of Salmonella phage P22 was mapped using phage deletion mutants. The DNA sequence in the region was re-examined in order to find an open reading frame consistent with the deletion mapping. Several discrepancies from the previously published sequence were discovered. The revised sequence revealed a single open reading frame of 242 codons with six likely translation initiation codons. On the basis of deletion and amber mutant phenotypes the second of these six sites was inferred to be the translation initiation site of the sieB gene. The sieB gene encodes a polypeptide with 192 amino acid residues with a calculated molecular weight of 22,442, which is in reasonable agreement with that estimated from polyacrylamide gels. The transcription start-site of sieB was identified by the use of an RNAase protection assay. The sieB promoter thus identified was inactivated by a two-base substitution in its -10 hexamer. The sieB gene of coliphage λ was also identified. The promoter for λ sieB was identified by homology to that of P22 sieB. sieB aborts the lytic development of some phages. P22 itself is insensitive to the lethal effect of SieB because it harbours a determinant called esc. It was found that the sieB gene encodes two polypeptides-SieB, which is the exclusion protein, and Esc, which is a truncated version of SieB that inhibits its action. Superinfecting P22 synthesizes an antisense RNA, sas, that inhibits synthesis of SieB but allows continued synthesis of Esc, thus allowing P22 to by-pass SieB-mediated exclusion. This translational switch induced by sas RNA is essential to vegetatively developing P22; a mutation that prevents this switch causes P22 to commit SieB-mediated suicide. It was also found that P22's Esc allows it to circumvent the SieB-mediated exclusion system of bacteriophage λ.

A relação entre bacteriófagos e virulência bacteriana é um modelo muito intrigante e pouco estudado na patogênese periodontal, uma vez que um patógeno periodontal pode ser lisogênico. O objetivo do nosso estudo é determinar a capacidade de fibroblastos gengivais humanos de induzir as cepas lisogênicas de Aggregatibacter actinomycetemcomitans. Dois experimentos foram realizados seguidos da titulação de fago. Os experimentos consistiram da co-cultura com fibroblastos gengivais humanos e três cepas de Aa [Aa29524, Aa2112, Aa29524(Ø2112)], não lisogênica, lisogênica e lisogênica induzida em laboratório, respectivamente. Em três momentos distintos (no experimento 1: 0, 2 e 4 horas; e no experimento 2: 2, 4 e 6 horas), o sobrenadante da co-cultura foi filtrado e cultivado overnight com a bactéria indicadora (Aa29524) e analisado para a capacidade de lisar a célula indicadora. Em ambos os experimentos, o sobrenadante da co-cultura de fibroblastos gengivais humanos com Aa lisogênico e Aa lisogênico induzido em laboratório, ao ser cultivado com a bactéria indicadora, promoveu lise da mesma, resultando no aumento da produção de fago. Pode-se concluir que, nesse estudo os fibroblastos gengivais humanos foram capazes de induzir cepas lisogênicas de Aggregatibacter actinomycetemcomitans. / The relationship between bacteriophages and bacterial virulence is a very intriguing, but rarely studied model in periodontal pathogenesis, as a periodontal pathogens can be lysogenic. The aim of our study is to determine the ability of human gingival fibroblasts to induce lysogenic strains of Aggregatibacter actinomycetemcomitans. Two experiments were performed followed by titration of phage. The experiments consisted of co-culture with human gingival fibroblasts and three strains of Aa [Aa29524, Aa2112, Aa29524 (Ø2112)], not lysogenic, lysogenic and lysogenic induced in the laboratory, respectively. In three different times (in experiment 1: 0, 2 and 4 hours, and in experiment 2: 2, 4 and 6 hours), the co-culture supernatant was filtered and cultured overnight with the indicator strain (Aa29524) and analyzed for ability to lyse the cell indicator. In both experiments, the supernatant of the co-culture of human gingival fibroblasts with Aa lysogenic and Aa lysogenic induced in the laboratory to be cultured with the indicator bacteria, caused lysis of the same, resulting an increased phage production. It can be concluded that in this study, human gingival fibroblasts were able to induce lysogenic strains of Aggregatibacter actinomycetemcomitans.