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An image processing system was programmed to automatically track and digitize the movement of amebae under phase-contrast microscopy. The amebae moved in a novel chemotaxis chamber designed to provide stable linear attractant gradients in a thin agarose gel. The gradients were established by pumping attractant and buffer solutions through semipermeable(More)
Expression of developmentally regulated membrane proteins of aggregating cells of Dictyostelium discoideum is subject to several control mechanisms. One of them involves periodic cyclic-AMP pulses as signals for gene expression. To increase the probability of selecting mutants specifically defective in the contact site A (csA) glycoprotein, one of the(More)
Merkl R., Hrádková I., Filip V., Šmidrkal J. (2010): Antimicrobial and antioxidant properties of phenolic acids alkyl esters. Czech J. Food Sci., 28: 275–279. Some phenolic acids alkyl esters (methyl, ethyl, propyl, butyl and hexyl) and determine their antioxidant and antimicrobial activities were prepared. The antimicrobial activity against the tested(More)
Antioxidant properties of monoand dihydroxyphenolic acids and their alkyl esters were examined, with emphasis on the relationship between their molecular structure and antioxidant activity. Test media with different tocopherol level were used for determining the oxidative stability: original refined sunflower oil (total tocopherols 149.0 mg/kg), partially(More)
Monoclonal antibodies raised against purified membranes from Dictyostelium discoideum were classified according to three criteria: type of antigen as revealed in immunoblots, developmental regulation of the target antigens, and location of the antigens on the cell surface. Some antibodies reacted with myosin, two with glycolipids. One group of antibodies(More)
Polyclonal and monoclonal antibodies were prepared against a glycoprotein (gp 64) of Polysphondylium pallidum previously shown to act as a target site of adhesion-blocking Fab prepared from antisera against whole membranes of aggregation-competent cells. The purified glycoprotein, with a nominal Mr of 64000, could be fractionated into two subspecies, gp 64I(More)
Tunicamycin acts on cell aggregation in Dictyostelium discoideum by changing cell movement and by inhibiting the EDTA-stable type of intercellular adhesion. Tunicamycin-treated cells show unco-ordinated pseudopodial activity such that pseudopods are simultaneously extended from all parts of the cell surface, and the cells are unable to move in straight(More)
In previous experiments it has been demonstrated that nerve growth factor (NGF), subsequent to its binding to specific membrane receptors, is internalized. Ultrastructurally, this internalized NGF is localized in membrane-confined compartments which ultimately fuse with lysosomes. The present experiments were designed, first, to evaluate whether a very(More)
Single amoebae of Dictyostelium discoideum were locally stimulated with microbeams of white and monochromatic light. Low illuminance stimulation favored formation of pseudopodia at the irradiated parts of the cells, high illuminance stimulation locally suppressed the extension of pseudopodia. When the high illuminance light spot was placed on any portion of(More)