Bibliographical references: leaves 162-181. / 181, [64] leaves, [16] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The inhibition of ruminant digestion by dietary tannins is a significant factor limiting livestock production... Characterisation of S. caprinus may provide essential insight into the ability of some ruminants to tolerate tannins. This thesis aims to identify and characterise the mechanism(s) by which Streptococcus caprinus tolerated the presence of tannins in its environment. S. caprinus employs at least two mechanisms to overcome the potential detrimental effects of tannins: degradation of tannic acid and production of a protective exopolysaccharide. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 2000

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 187-206).

Streptococcus pneumoniae is a gram-positive bacterium that can be found in both healthy carriers as well as in people that have developed disease. One of the major virulence factors of pneumococci is their polysaccharide capsule. Based on the capsule that surrounds the bacteria, pneumococci are divided into at least 90 different serotypes. Some serotypes seem to be more related to virulence than others. I have with comparative genome hybridization microarray technique, studied gene differences between 18 epidemiological well-characterised pneumococcal strains with different potential to cause disease. A microarray chip based on two sequenced pneumococcal genomes, R6 and TIGR4, has already been designed. According to Hierarchical clustering, both the serotype and the genetic type as assessed by MLST (sequence type or ST) seem to have impact on the relationship of clinical isolates. Most clinical isolates of the same serotype are clustered together except for serotype 14 isolates that seem to be more divergent. Further more the number of genes that are divergent between clinical isolates compared to R6 and TIGR4 differ from 65 to 289. Preliminary results indicate that although there is diversity among clinical isolates some are more closely related to each other then others. Absent genes seem to be evenly distributed among all 18 clinical isolates tested but hypothetical genes and genes for cell envelope are two groups of role categories that are absent to the largest extent in all isolates. According to results from microarray analysis, a gene region, spr0112-spr1015- is present in all type 9V isolates and absent in many isolates of serotype 14, 19F and 7F. These results have been confirmed by polymerase chain reaction (PCR). Conserved genes in a region around the capsule genes have been sequenced to identify marker genes for a capsulular switch between serotype 9V and 14. Preliminary results of the sequencing showed that as much as 750kb might have been transferred in the event of capsular switch.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

In order to improve production efficiency and profitability in tilapia aquaculture, further research is needed to develop methods to improve weight gain, feed utilization, and immune function of these fish. In this regard, numerous studies with several fish species have reported that dietary nucleotides can enhance growth performance, immune responses and disease resistance. Therefore, two feeding experiments were conducted to investigate the effects of a purified nucleotide mix on juvenile Nile tilapia, Oreochromis niloticus. A basal diet was formulated to contain 34% crude protein from fishmeal and soybean meal. A nucleotide mix containing salts of cytidine, uridine, adenosine, inosine, guanosine, and thymine was supplemented to the basal diet at 0.5, 1 and 2% of dry weight. In the first experiment, three replicate groups of 15 fish were fed the experimental diets. At the end of 8 weeks, weight gain, feed efficiency and survival were computed. Blood samples were analyzed for neutrophil oxidative radical production and plasma lysozyme activity. In the second trial, three replicate groups of 20 fish were fed the same experimental diets. At the end of 4 weeks, blood and kidney samples were analyzed for macrophage extracellular and intracellular superoxide anion production, blood neutrophil oxidative radical production, plasma lysozyme activity, and peripheral blood lymphocyte proliferation. Then, 12 fish per treatment were challenged with Streptococcus iniae, via intraperitoneal injection, and mortality was recorded for 21 days. Results showed that none of the nucleotide-supplemented diets induced significant (P < 0.05) effects on growth performance. On the other hand, the 0.5% treatment produced significantly (P < 0.05) higher intracellular superoxide anion (O2-) production and both the 0.5 and 1% treatments significantly (P < 0.05) increased lymphocyte proliferation. The disease challenge failed to show significant survival differences among treatments; however, the 2% nucleotide treatment tended to produce higher survivability. Results from both experiments lead to the conclusion that this particular nucleotide mix does not provide marked improvements in growth performance and disease resistance; however, dietary nucleotide supplementation did affect some components of the immune system of Nile tilapia.

Bibliography: leaves 250-227. / 251 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The genetic loci encoding capsular polysaccharide synthesis have been characterized for all members of streptococcus pneumoniae serogroup. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1999?

Group B streptococcus (GBS, S. agalactiae) and human ureaplasmas (U. parvumand U. urealyticum) are two clinically and phylogenetically related, potential perinatal pathogens. Their relationships between genotypes and pathogenesis of GBS and ureaplasma infection were still not well understood, one of the reason is that both of them are still short of a very practical genotyping system. In the study, to solve the above problem we developed genotyping systems for the organisms (the second section). For human ureaplasmas, based on four genes/gene clusters (rRNAgene clusters, the elongation factor Tu genes, urease gene complexes and multiplebanded antigen genes), we designed many primer pairs suitable for developing species identification assays for the two newly established human ureaplasma species (U. parvum and U. urealyticum). Further, based on the heterogeneity of ureaplasma multiple banded antigen gene (which contains species- and serovar-specific regions), we developed genotyping methods for each ureaplasma species.For GBS, based on three sets of molecular markers (capsular polysaccharidesynthesis gene clusters, surface protein antigen genes and mobile genetic elements),we developed a genotyping system. The primary evaluation of the genotyping systems showed that the genotyping systems were practical alternative assays for the conventional serotyping and they will be useful to further explore the relationships between genotypes and pathogenesis of GBS and ureaplasma infection. In the study, we introduced novel data and tools into GBS and ureaplasma studies especially from genomic- and bioinformatics-based molecular microbiology(the third section). For two newly established human ureaplasma species, based on the U. parvum serovar-3 genome, and using the above four important genes/geneclusters, we exposed some interesting problems in the understanding of newureaplasma taxonomy especially in the post genomic era. For GBS, we studied the two published full genomes and exposed some new problems or possible future new research fields. In particular we found the two finished and one ongoing GBS genomes were all non-typical and suggest that future genomic project had better have genetic population structure viewpoint. Finally, we suggested that integrated studies of the two potential or conditional perinatal pathogens, from the viewpoint of evolution, would provide a new understanding angle of the pathogenesis of the two organisms. Studies suggested that during coevolution, human ureaplasmas(especially U. parvum) became friendlier than their ancestors to their human host (by losing most of its virulence genes); however, GBS tried to increase its invasive abilities (by getting more virulence genes) to fight against the human host attack.

Thesis (M. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaves 217-261) Also available in print.

Thesis (doctoral)--Göteborg University, 1994. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Lunds Universitet, Malmö, 1984. / Extra t.p. with thesis statement inserted. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.