Thesis--University of Helsinki. / Includes bibliographical references.

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published_or_final_version / Anatomy / Master / Master of Philosophy

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Twenty-three marine and two terrestrial gram-negative bacteria were examined by electron microscopy for the effect on the outer membrane of the cells of washing the organisms successively in 0.5M NaCl and 0.5M sucrose. Six marine bacteria lost their outer membranes completely, three lost large segments but not all of their outer membranes, and six retained their outer membranes but with either gross distortions of the outer membrane and/or segments of outer membrane removed from some cells. The remaining eight marine and two terrestrial bacteria appeared to have continuous outer membranes after application of the wash procedure. / Eighteen of the twenty-three marine bacteria employed in the wash treatment study and two terrestrial bacteria were examined for the effect of washing and suspending the organisms in various solutions with respect to lysis of the cells and Optical Density (O.D.) changes of suspensions. / A spectrum of lytic susceptibility was observed among the marine bacteria ranging from those organisms which lysed in distilled water after exposure to Mg('2+) through organisms which lysed upon suspension in distilled water after pre-exposure to NaCl but which failed to lyse in distilled water if pre-exposed to Mg('2+) to organisms which failed to lyse in distilled water even after exposure to NaCl. E. coli and Ps. aeruginosa also fell within this spectrum. / After exposure to NaCl and subsequent suspension of these organisms in decreasing concentrations of either NaCl, KCl or MgCl(,2), concentrations of KCl two to three times that of NaCl or ten to four hundred times that of MgCl(,2) could protect most marine organisms from lysis or larger decreases in the O.D. of their suspensions. However, three marine and both terrestrial bacteria required only equal concentrations of KCl or NaCl to effect protection. / No overall distinction can therefore be made between marine and terrestrial bacteria with respect to the status of the outer membrane of these organisms after washing them in NaCl and sucrose solutions or the sensitivity of the two groups of organisms to lysis in distilled water after pre-exposure to NaCl or MgCl(,2).

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A system was developed to study membrane transport in isolated human fibroblast plasma membrane vesicles, avoiding potential complications of intracellular binding and metabolism in the intact cell. Ten-fold enrichment of plasma membranes after subcellular fractionation was confirmed with appropriate markers. Transport competence was established by the following criteria: osmotic sensitivity, stereospecificity, temperature dependence, sodium gradient stimulation, response to ions and ionophores, saturability, and exchange properties. Methotrexate uptake was osmotically sensitive, temperature sensitive, saturable, and inhibited by folinic acid and phosphate. Measurement of lysine uptake was complicated by binding and lack of sodium dependence, but was stimulated by an interior-negative membrane potential, and intravesicular lysine or arginine. Exchange properties of the lysine carrier were exploited to assess its function in fibroblasts from patients with the Mendelian phenotype, lysinuric protein intolerance (LPI). LPI vesicles were not different from controls in their lysine transport phenotype.