Univ., Diss.--Göteborg, 2007. / Enth. außerdem 5 Zeitschriftenaufsätze.

Thesis (Ph.D.)--Göteborg University, 2007. / Includes bibliographical references.

No description available.

No description available.

Thesis (Ph. D.)--Washington State University, December 2006. / Includes bibliographical references.

published_or_final_version / abstract / toc / Botany / Master / Master of Philosophy

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Plant Biology." Includes bibliographical references.

Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmacognosy Diploma thesis Author: Dana Kettnerová Supervisor: PharmDr. Jan Martin, Ph.D. Title of diploma thesis: Isolation of plant organelles and study of transport mechanisms Key words: isolation, chloroplast, protoplast, vacuole, cell wall Isolation of plant organelles and other cellular components is essential for the study of physiological and pathological processes within the plant cell. It is possible to analyze cell structures, detect accumulation of certain metabolites, ions, enzymes and other substances thanks to the isolation. The goal of this diploma thesis was to provide an overview of isolation methods used for the isolation of cell wall, protoplasts, chloroplasts and vacuoles of plant cells. Isolation processes used for individual types of cell structures, the pros and cons of the various isolation methods, components of used media and their functions, as well as the structure and function of individual plant structures were described.

Phosphorous in its inorganic form, orthophosphate (Pi), is found in every compartment of the plant cell and serves as a substrate, product or effector for a wide range of metabolic processes. Several Pi transporters exist in plants and these help regulate Pi homeostasis within different cellular compartments. The PHT4 family of organellar Pi transporters consists of six members in the model plant Arabidopsis thaliana, and five of these are localized to plastids. I used gene expression analyses and reverse genetics to demonstrate functional specialization for the PHT4 family members with a focus on PHT4;1 and PHT4;2. The PHT4;1 Pi transporter is localized to chloroplast thylakoid membranes and it is expressed in a circadian manner. Plants that lack a functional copy of the PHT4;1 gene have reduced rosette size and altered responses to photooxidative stress. The PHT4;2 transporter is localized to heterotrophic plastids in roots and other sink organs and pht4;2 mutants exhibit decreased starch accumulation, which is consistent with a defect in Pi export, and increased rosette size, which is caused by increased cell proliferation. These results confirm that PHT4;1 and PHT4;2 have specialized functions and that plastidic Pi homeostasis influences broad aspects of plant metabolism, including abiotic stress response and control of lateral organ growth.

The capacity of pea root plastids for galactolipid synthesis was investigated utilizing radiolabelled acetate and UDP-galactose. Galactolipid biosynthesis was completely dependent on an exogenous supply of UDP-galactose. UDP-galactose stimulated both total lipid biosynthesis from acetate and the proportion of radioactivity accumulated in monogalactosyldiacylglycerol (MGDG). The proportion of MGDG synthesized was saturated at 30$ mu$M UDP-galactose and represented approximately 30% of the total lipid radioactivity after a one hour incubation. However, total lipid biosynthesis continued to increase with concentrations of UDP-galactose up to 75$ mu$M while the proportion of radioactivity in MGDG remained at 30%. MGDG biosynthesis was always accompanied by a corresponding decrease in the amount of diacylglycerol (DAG) accumulated. Digalactosyldiacylglycerol (DGDG) synthesis was not routinely observed in these experiments. These results suggest that the in vitro pathway for MGDG synthesis in the root plastids of pea (an 18:3 plant) is similar to 16:3 plants (FFA's$ to$PA$ to$DAG$ to$MGDG). The endogenous lipids, consistent with the thought of pea as an 18:3 plant, contained 80% C$ sb{18}$ in the fatty acids of MGDG, DGDG, TG and PC. However, in labelled acetate experiments palmitate was the predominately labelled fatty acid in all lipids except PC (where 80% was 18:1). The precursors PA and DAG had ratios of 16:0, 18:0, and 18:1 similar to that of MGDG. 70-80% of the label was associated with the sn-2 position of glycerolipids. The cofactors required for fatty acid synthesis were generally not as required for galactolipid synthesis. The results suggest that galactolipid synthesis relies primarily on endogenous DAG and only partly involves de novo fatty acid synthesis. (Abstract shortened by UMI.)