Ribosomal RNA is synthesized at constant rate during most of the cell cycle in heat-shock synchronized populations of Tetrahymena pyriformis. Early in each macronuclear S-period the rate of synthesis increases abruptly, concomitant with replication of the genes coding for ribosomal RNA. The increase is prevented by inhibitors of DNA replication, added prior to the S-period. Similarly, in cultur...

The amount of thymidine-H(3) converted to thymidine-H(3) monophosphate in 30 min formed the basis for assays of thymidine kinase in cell extracts from Tetrahymena pyriformis. The optimal concentration of adenosine triphosphate is lower than that required by other cell types. Thymidine triphosphate does not exercise any feedback control of the enzyme. Other deoxyprimidine nucleotides were tested...

Chemotactic properties of amino acids (L-alanine, glycine and L-lysine) and their oligopeptides (10(-6) M) and binding sites to these ligands were investigated in two unicellular models, the heterotrophic Tetrahymena pyriformis and the auxotrophic Dunaliella salina. Chemotaxis of Dunaliella induced by simple amino acids and their derivatives demonstrated that binding sites (receptors) for food ...

Address: 1GSF National Research Centre for Environment and Health, Institute for Bioinformatics, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany, 2UNC School of Pharmacy, Medicinal Chemistry and Natural Products, Beard Hall, Room 327A, Chapel Hill, NC 275997360, USA, 3Varese, Italy, 4Kalmar, Sweden and 5Université Louis Pasteur de Strasbourg, Institut de Chimie, 4, rue B. Pascal, F-670...

Vibrio fischeri proliferates in a sessile, stable community known as a biofilm, which is one alternative survival strategy of its life cycle. Although this survival strategy provides adequate protection from abiotic factors, marine biofilms are still susceptible to grazing by bacteria-consuming protozoa. Subsequently, grazing pressure can be controlled by certain defense mechanisms that confer ...