Pseudomonas chlororaphis PA23 inhibits several root pathogens in both the greenhouse and field. A LysR-type transcriptional regulator (LTTR) called PtrA (Pseudomonas transcriptional regulator A) that is essential for Sclerotinia sclerotiorum antifungal activity was discovered through transposon mutagenesis. P. chlororaphis PA23 produces the antibiotics phenazine 1-carboxylic acid, 2-hydroxyphenazine and pyrrolnitrin, and several additional products that contribute to biocontrol. Phenotypic assays and proteomic analysis have revealed that production of these secondary metabolites are markedly reduced in a ptrA mutant. Most LTTRs regulate genes that are upstream of and divergently transcribed from the LTTR locus. A short chain dehydrogenase (scd) gene lies immediately upstream of ptrA in the opposite orientation. Characterization of an scd mutant, however, has revealed no significant changes in antifungal activity compared to wild-type PA23. Gene expression analysis of the ptrA mutant indicates that ptrA may exert its regulatory effects through the Gac-Rsm network, and may be controlling expression of the scd gene. Collectively these findings indicate that PtrA is an essential regulator of PA23 biocontrol and is connected to other regulators involved in fungal antagonism.

As the requirements for more efficient and economical crop production emerge, so the need for a better understanding of plant growth and development is felt. It is especially the need to understand means by which man may influence growth and development in order to achieve greater productivity, that requires attention. Observation and analysis of plant growth and the concomitant study of plant components, organs and chemicals, provides one of the research oriented approaches to gaining an understanding of the mechanism of growth control. Ultimately, the extent of reproductive growth (fruiting) or the bearing capacity in all plants is governed by the volume and area of vegetative growth and the supply of substances required for growth produced by those vegetative organs. Productivity then, is governed by the efficiency of conversion of solar energy to chemical energy and by the relative ability to store this energy. Plant shoots play a fundamental role in both assimilation and storage of carbohydrates. Given the same growing conditions, similar plants sometimes exhibit different rates of growth. For example, ontogenetically juvenile plants exhibit differences in form and vigour in comparison with ontogenetically adult plants. Although the genotype of such adult and juvenile plants may vary only in expression and not in constitution, there does appear to be some property in juvenile plants which induces the characteristic enhanced vegetative vigour. It is this property, amongst many others, which needs to be better understood, for it is a potential means of gaining greater yields from plants without alterations being made to the environment. A high degree of organisation of growth processes must exist to account for the orderly development of plants. A few organic compounds that influence certain biochemical and physiological reactions have been isolated from the As the requirements for more efficient and economical crop production emerge, so the need for a better understanding of plant growth and development is felt. It is especially the need to understand means by which man may influence growth and development in order to achieve greater productivity, that requires attention. Observation and analysis of plant growth and the concomitant study of plant components, organs and chemicals, provides one of the research oriented approaches to gaining an understanding of the mechanism of growth control. Ultimately, the extent of reproductive growth (fruiting) or the bearing capacity in all plants is governed by the volume and area of vegetative growth and the supply of substances required for growth produced by those vegetative organs. Productivity then, is governed by the efficiency of conversion of solar energy to chemical energy and by the relative ability to store this energy. Plant shoots playa fundamental role in both assimilation and storage of carbohydrates. Given the same growing conditions, similar plants sometimes exhibit different rates of growth. For example, ontogenetically juvenile plants exhibit differences in form and vigour in comparison with ontogenetically adult plants. Although the genotype of such adult and juvenile plants may vary only in expression and not in constitution, there does appear to be some property in juvenile plants which induces the characteristic enhanced vegetative vigour. It is this property, amongst many others, which needs to be better understood, for it is a potential means of gaining greater yields from plants without alterations being made to the environment. A high degree of organisation of growth processes must exist to account for the orderly development of plants. A few organic compounds that influence certain biochemical and physiological reactions have been isolated from the wide array of organic and inorganic substances found in plant extracts. A growing body of evidence suggests that such growth regulatory compounds are ubiquitous in plants; are active at exceedingly low concentrations and are under genetic control. Plant hormones are almost certainly involved in directing or regulating plant growth and development. The subject of the present research concerns the characterization of differences in shoot growth of juvenile and adult phases of a commercial Citrus cultivar and an investigation of the possible role which plant hormones may play in such differences. In add i tion to a comprehensive literature survey, three separate sets of experiments were conducted. In the first, an analysis of the components and parameters of the difference in vegetative shoot growth of adult and juvenile scions was carried out. Anatomical and ultrastructural comparisons were also made. In the second set of experiments the endogenous levels of gibberellins, cytokini ns and inhibitors of buds and other tissues, which might playa role in the regulation of shoot flush growth, were examined. Specific extractions were performed and appropriate bioassay techniques were employed for the three hormone classes investigated. In the final set of experiments the effects of synthetic plant growth regulators on shoot flush growth were monitored. The growth regulators were applied by means of trunk injections or as droplets on shoot terminal buds. These experiments were planned and executed with the above mentioned concepts and ideals in mind. The objective of the project was to contribute in some measure to the knowledge which will allow better use to be made of available natural resources. / Thesis (Ph.D.)-University of Natal, Pietermartizburg, 1982.

This work is a part of a large project in our laboratory that is aimed toward characterization of prokaryotic transcription regulators from different families and their interactions with small-molecule effectors. My study was focused of IclR family of transcriprion regulators, specifically on its founding member Isocytrate Lyase Regulator (IclR) from E.coli and AllR regulator from E.coli, which share 42% sequence identity with IclR. I used a combination of biophysical, biochemical and structural biology techniques to explore the mechanisms by which IclR and AllR interact with their effectors. I performed site-directed mutagenesis experiments in order to research the role of individual amino acids in interaction of AllR regulator with its previously identified effector glyoxylate and to test whether oligomerization plays a role in effector-induced signal transduction by AllR. Using differential light scattering, which allows high-throughput screening of small molecules for thermostabilization of proteins, I identified potential effctors for the IclR regulator. The physiological relevance of these candidate molecules was tested in-vitro and in-vivo and their interaction with IclR was characterized by Isothermal Titration Calorimetry and X-ray Crystallography.

Precise regulation of heterotrimeric G-protein signaling is important for maintaining proper cardiovascular system function. Indeed, G-protein signaling is frequently upregulated during cardiovascular disease suggesting that identifying mechanisms for inhibiting G-protein signaling may be an effective therapeutic strategy for the treatment and prevention of disease. The work presented in this thesis is directed at two RGS proteins, RGS2 and RGS5, the two highest expressing RGS proteins in VSMCs. Despite the large number of studies published on them, there is still much to be learned about the specific G-protein pathways that each RGS protein controls. Using genetic and molecular models, we set out to identify novel regulatory pathways controlling RGS2 and RGS5 function. We hypothesize that characterizing the determinants and regulation of RGS protein function will provide a better understanding of the signaling that occurs within VSMCs under both physiologic and pathophysiologic conditions. Our work presented in the first three studies of this thesis, describes novel regulatory pathways that are involved in regulating RGS2 protein function. We describe the production of RGS2 protein isoforms that are the result of alternative translational start site usage. Interestingly, the expression pattern of these proteins is controlled by the signaling status of the cell. In the second two studies, we identify a functional consequence of RGS2-interaction with the plasma membrane. We show that this is dependent on the interaction between the amphipathic α-helix and anionic phospholipids present in the plasma membrane. We further show that disruptions in this interaction, as occurs in the human population, can lead to reduced RGS2 function and thus potentially hypertension. Finally, our last study focuses on the function and regulation of RGS5, the single highest expressing RGS protein in VSMCs. We show that the regulation of RGS5 is dependent, similar to other VSMC-specific genes, on the activity of SRF and myocardin. However, interestingly, RGS5 expression is further controlled by the extent of DNA methylation that occurs in its proximal promoter. We show that this is an important regulator of RGS5 expression both in development as well as during disease, specifically in-stent restenosis.

This work is a part of a large project in our laboratory that is aimed toward characterization of prokaryotic transcription regulators from different families and their interactions with small-molecule effectors. My study was focused of IclR family of transcriprion regulators, specifically on its founding member Isocytrate Lyase Regulator (IclR) from E.coli and AllR regulator from E.coli, which share 42% sequence identity with IclR. I used a combination of biophysical, biochemical and structural biology techniques to explore the mechanisms by which IclR and AllR interact with their effectors. I performed site-directed mutagenesis experiments in order to research the role of individual amino acids in interaction of AllR regulator with its previously identified effector glyoxylate and to test whether oligomerization plays a role in effector-induced signal transduction by AllR. Using differential light scattering, which allows high-throughput screening of small molecules for thermostabilization of proteins, I identified potential effctors for the IclR regulator. The physiological relevance of these candidate molecules was tested in-vitro and in-vivo and their interaction with IclR was characterized by Isothermal Titration Calorimetry and X-ray Crystallography.

This thesis pursues the study of non-algebraic and non-Kahler compact complex manifolds by traditionally algebraic methods involving sheaves, cohomology and K-theory. To that end, Bott-Chern cohomology is developed to complement De Rham and Dolbeault cohomology. The first substantial chapter is devoted to the construction of Bott-Chern cohomology, including products. The next chapter is an investigation of Pic0(X) for non-Kahler complex manifolds. The next chapter uses line bundles represented by classes in this Pic0(X), along with Cartier divisors, to define a group of twisted cycle classes, generalizing a previous algebraic definition. On this group of twisted cycle classes, we use currents to construct a regulator map into Bott-Chern cohomology. Finally, in a chapter of conjectural statements and future directions, we explore the possibility of an alternate regulator using a cone complex of currents. We also conjecturally define a height pairing for certain kinds of compatible twisted cycle classes. / Mathematics

Thesis (Ph. D.)--Oregon State University, 1990. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 49)

Thesis (Ph. D.)--University of Washington. / Bibliography: l. 72-75.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references (leaves 62-64). Also available in electronic version. Access restricted to campus users.