Some characteristics of fucidin biosynthesis]

Some features of fusidin biosynthesis by 2 strains of Fusidium coccineum were studied proceeding from the peculiar properties of the antibiotic molecule structure. It was found that an increase in the levels of the carbon sources in the medium stimulated the biosynthesis of fusidin, while excessive concentrations of nitrogen especially in its inorganic and amino acidpeptide forms stimulated the organism growth and lowered the antibiotic activity levels. The concentration of nitrogen in the medium is considered as one of the possible control mechanisms in the processes of the fungus growth and biosynthesis of fusidin.     

Functional characteristics of the recA gene from Serratia marcescens strain Sb

The cloned recA gene from Serratia marcescens Sb was expressed and complemented defects in the UV repair, recombination, and SOS induction of an Escherichia coli host deleted for recA. Moreover, the Serratia gene, recA (Sm), supported the same frequency of recombination per unit length of DNA as did the homologous Escherichia coli gene, recA(Ec).     

Isolation and properties of glucose-6-phosphate dehydrogenase from human cultivated cells]

A new procedure for purification of glucose-6-phosphate dehydrogenase resulting in an electrophoretically homogenous preparation made up of 5.10(8) cells (390 mg of protein) is proposed. The enzyme yield is more than 20%. The molecular weights of a subunit and a native enzyme are 55000 and 220000, respectively. The isoelectric point for the protein lies at 4,8. The kinetics of the enzyme thermal inactivation obey the first order equation with the inactivation rate constant of 6.10(-3) min-1.     

Harderian gland ultrastructure of the black sea bottlenose dolphin (Tursiops truncatus ponticus)

Examination of the Harderian gland structure of the Black Sea bottlenose dolphin, Tursiops truncatus ponticus, at macroscopic, microscopic, and electron microscopic levels shows significant sexual dimorphism. The epithelial cells of male and female glands are different cell types, capable of producing chemically different products. Secretory cells in both sexes contain secretion granules that produce a secretion consisting mainly of proteins and carbohydrates, but thought to be sex-specific in composition. The female glands also contain lipid secretion granules. It is suggested that in the bottlenose dolphin the Harderian gland functions to produce sexually distinct pheromones and may have other physiological activities, e.g., participating in local immunological or endocrine-related reactions. © 1994 Wiley-Liss, Inc.     

Radiation-induced instability of yeast chimeric chromosomes

Instability of the I chimeric chromosome of the yeast Saccharomyces induced by gamma-irradiation has been studied. The chimeric chromosome analysed contained an integrated pYF91 plasmid. Cells of the integrant were irradiated and then mated with non-irradiated cells of the proper tester strain marked by ade1 mutation (red colour of colonies). We isolated 10 hybrids with pink colonies on selective medium. They displayed high degree of mitotic instability during growth on nonselective medium, segregating red colonies (15 to 90% of the total). Tetrad analysis showed that some of the unstable chromosomes exhibited lethal effect in haploids, while others were viable and could pass through meiosis retaining their instability.