No description available.

No description available.

TCP genes comprise a large family of genes that have been implicated in a diverse range of plant developmental pathways ranging from lateral branching (Doebley et al, 1997) to organ symmetry (Luo et al, 1999) and leaf curvature (Nath et al, 2003; Palatnik et al, 2003). I studied three closely related Arabidopsis TCP genes, one of which was recovered in an enhancer trap screen to identify downstream targets of the regulator of inflorescence architecture, BREVIPEDICELLUS (Douglas and Riggs, 2005). The enhancer trap marker line served as a reporter for TCP15 expression. Data mining has revealed a possible link between TCP15 and the hormone auxin. Using the DR5::GUS molecular reporter for auxin accumulation I found that TCP15 and the related TCP14 genes limit auxin maxima in seedling and reproductive tissues and that auxin transport is necessary for correct TCP15 expression. The closely related TCP8 gene was found to regulate leaf shape as demonstrated by decreased leaf index values. The rounder leaves of tcp8 plants also exhibited increased adaxial trichome and stomatal densities resulting in significantly decreased spacing between adjacent cells. tcp8 leaves showed increased serration density suggesting that TCP8 limits marginal outgrowth. Vein patterning was also perturbed in the mutants. Vein loops were rounder and smaller, and decreased loop subdivision indicated that vein patterning is retarded in the mutant. TCP8 evokes organ-specific effects on vascular patterning as mutant rosette leaves showed increased vascular complexity, whereas mutant cauline leaves showed decreased vein complexity. These results suggest that TCP8 is necessary for correct leaf development. The Arabidopsis genome contains 24 TCP genes, many of which have not been characterized. Studies of these genes will lead to the identification of additional factors necessary to control plant architecture and enable us to optimize plant growth and yield using genetic engineering.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 124-138) / Microfiche. / xiii, 138 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 93-117). / Microfiche. / x, 117 leaves, bound ill. (some col.) 29 cm

Bibliography: leaves 212-235 / xix, 248, [28] leaves, [15] leaves of plates : 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 Genetics, 1992

The traditional view of the genome is based on the dogma that genetic information flows from DNA to RNA to protein. Genes have essentially been synonymous with proteins, with RNA viewed primarily as an intermediate template for protein translation. Intriguingly, only ~2% of the human genome encodes proteins, and the number of protein-coding genes (~20,000) is similar between humans and the simple nematode worm.I have been involved with the analysis of a large-scale transcriptome study, intiated by the RIKEN Genomic Sciences Centre in Japan. As part of this work, it was discovered that the genome carries instructions for tens of thousands of “non protein-coding RNAs” (ncRNAs)(please refer to Appendix A to view the original articles that appeared in Science). The significance of these ncRNAs remains a matter of intense interest and debate. Some have argued that these ncRNAs are simply transcriptional noise, while others have suggested that they comprise a critical regulatory system, which directs the complex patterns of gene expression that underlie differentiation and development.To investigate this further, I have conducted a series of studies that explore the expression and evolution of ncRNAs in mammals. Firstly, I established a comprehensive, on-line database of ncRNAs. This collection provides information on more than twenty thousand ncRNAs, and has proven a valuable resource for ncRNA studies. Secondly, I have systematically analyzed the conservation of known functional ncRNA subsets. I found that small ncRNAs (microRNAs and snoRNAs) were well-conserved similar to protein-coding sequences, whereas longer functional ncRNAs were not. These results indicate that long ncRNAs are evolving more rapidly than other functional genomic elements, and suggest that many of the recently-discovered ncRNAs – most of which are long and of unknown significance – might still be functional, despite having poor sequence conservation. Thirdly, I have shown that many ncRNAs are derived from genuine transcripts, whose expression appears regulated in a biologically-relevant manner. Fourthly, I helped develop a computational strategy to identify extremely large ncRNAs and discovered >60 novel candidates, several of which were characterized experimentally. Prior to this work, only a handful of extremely large ncRNAs had been previously described, and these play critical roles in processes such as genomic imprinting and X chromosome inactivation. This study represented the first systematic discovery of extremely large ncRNAs. Finally, I designed custom microarrays and profiled ncRNA expression across the development of CD8+ T cells. CD8+ T cells serve an important role in immunity by killing virus-infected and tumour cells, and transit through a series of functionally-distinct developmental stages. I found that ~200 novel ncRNAs are dynamically expressed during CD8+ T cell development.Taken together, my findings indicate that ncRNAs are a major, regulated output of the mammalian genome, and are consistent with the notion that ncRNAs represent an important, previously-unrecognised biological control system.

Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / Salmonella is a genus of Gram-negative bacteria responsible for food-borne enteritis and systemic fever. Salmonellosis continues to be a serious health burden worldwide. Lipopolysaccharide (LPS) is the dominant lipid component of the outer membrane of Salmonella. LPS is composed of lipid A, an oligosaccharide core, and a polymer of O units known as O antigen. Wzz proteins control the length of O antigen by an unknown mechanism. While O antigen is essential for S. typhimurium virulence, the significance of length regulation by Wzz is not known. This study investigates the pathogenic relevance of the wzz genes in S. typhimurium. In addition to the previously recognised wzz gene (WZZ[subscript]ST), a second gene with this function (WZZ[subscript]fepE) was identified in the S. typhimurium genome. Whereas WZZ[subscript]ST specifies the production of long LPS chains with a modal length of 16-35 O antigen repeat units, WZZ[subscript]fepE conferred very long chains containing> 100 O antigen repeat units. Strains carrying mutations in one or both wzz genes were constructed to investigate the role of wzz genes in virulence. It was found that wzz-controlled regulation of O antigen length was essential for resistance to the bactericidal activity of serum complement, while studies in the mouse model of infection found that wzz genes are essential for full virulence. The wzz double mutant was complemented with heterologous wzz genes from a variety of bacterial sources. Despite variable sequence similarity of the encoded Wzz proteins each was functional in the S. typhimurium host, generating a panel of isogenic O antigen length variants. This panel of variants was used to define a minimum length requirement for complement resistance and identified relationships between O antigen length and complement consumption. Finally, the regulation of O antigen chain length was investigated. It was found that growth either in iron limiting conditions or in serum caused an increased production of LPS with very long O antigen chains (conferred by WZZ[subscript]fepE), resulting in increased complement resistance. The constitutive activation mutation of the phoPQ regulator (Phop) results in an altered O antigen distribution phenotype consistent with down-regulation of wzz genes. However PhoPQ had no effect on production of Wzz[subscript]sT as determined by immunoblotting with an antiWZZ[subscript]ST antiserum. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1152141 / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2005

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Angiogenesis is the formation of new blood vessels from pre-existing vessels. It is highly regulated in a normal physiological system. Dysregulated angiogenesis is associated with a number of pathological states such as cancer and rheumatoid arthritis. Thus angiogenesis is proposed as a target for control of such diseases. The identification of novel genes involved in angiogenesis will improve the likelihood of the development of efficacious drugs. To identify genes essential to angiogenesis, we used an in vitro model of capillary tube formation and a PCR based subtraction hybridisation approach for isolation of regulated genes. We identified 125 different genes including 96 known and 29 novel genes and of these, 84 genes were confirmed to be regulated during the formation of capillary tubes. From the 125 isolated genes, one novel gene displayed characteristics suitable for further investigation. The gene, p73RhoGAP is a new member of the RhoGAP family. It is highly upregulated at 3 and 6 h in the tube formation process but only in an angiogenic milieu with little or no regulation seen under non-angiogenic conditions, and is restricted in its expression to vascular cells. Thus, we propose that p73RhoGAP is called VASGAP. Bioinformatics analysis of the protein sequence revealed the presence of a putative Rho GAP domain, indicating a potential role in the activation of RhoGTPases. Our study suggests that VASGAP displays RhoGAP activity for Rho but not Rac or Cdc42. RhoGTPase activity assays demonstrated that mutation of the conserved arginine at residue 82 (R82A) in the RhoGAP domain is crucial to the p73 effect on Rho. VASGAP localises to actin stress fibres. To characterise the function of VASGAP, knockdown of the protein was achieved by adenovirus delivery of VASGAP antisense into EC. Such VASGAP depleted cells showed enhanced actin stress fibres and basal permeability consistent with alteration of Rho activity. Cell migration, proliferation and capillary tube formation were inhibited, and enhanced apoptosis was evident. In an in vivo model of angiogenesis, antisense of VASGAP inhibited blood vessel invasion. Thus, the results suggest VASGAP is an important and novel modulator of angiogenesis and cell survival and displays many of the features worthy of a drug target. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1170778 / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2005

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Barley net-and spot-form of net blotch, caused by two formae of the hemibiotrophic fungus Pyrenophora teres, are two of the major diseases affecting barley crops worldwide. In this study, the method of suppression subtractive hybridisation was used to isolate barley epidennal genes that were differentially expressed in the early stages of both net blotch incompatible compared to compatible interactions. As a result, two subtracted libraries of cDNA clones comprising mainly of gene transcripts of low abundance were generated. Quantitative real-time PCR was employed to verify and profile the differential expression of forty-five subtracted transcripts during the first 48 hours of infection, resulting in the identification of twenty-eight clones that were pathogen-induced and differentially expressed. These clones were grouped into one of eight clusters depending on the kinetics of their expression, and they included groups of genes that were up-regulated early (within 3 hai) and later (24 hai) in both barley-P. teres incompatible interactions. Among the differentially expressed clones were those with sequence homology to genes that encode proteins involved in calcium signal perception (e.g. a calcineurin B-like protein), detoxification (e.g. multidrug transporters), carbohydrate metabolism (e.g. an invertase), and signal transduction (e.g. protein kinases). Furthennore, the expression profiles generated for each individual gene cluster were similar for both net-and spot-form interactions, indicating that the resistance-associated defence response against both pathogens may be mediated by the same molecular mechanism. The differentially expressed genes are discussed with respect to their potential functional role in contributing to net blotch disease resistance. In addition, a model detailing early events that may take place in the barley-P. teres incompatible interaction is presented. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1286782 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007