The Mechanism of Antibacterial Action of the Lantibiotic Warnerin

Microbiology - Evidence of membranotropic activity of the lantibiotic warnerin was obtained for warnerin-sensitive bacteria Staphylococcus cohnii VKM-3165. Warnerin attack led to increased...     

The effect of blood serum proteins from the seal on the analgetic action of narcotic analgesics]

The protein fraction isolated from blood of seal, Phoca groenlandica, has been found to produce hyperalgesic effect on rats exposed to thermic or electrocutaneous nociceptive stimulation, but fail to affect writhes provoked by intraperitoneal injection of acetic acid solution on mice. When combined with morphine, the fraction lowered completely its narcotic analgetic action in the above mentioned tests. On the contrary, these same proteins combined with promedol or fentanil enhanced and prolonged analgetic effect of the latter. Tested in vitro the protein showed neither opioid nor anti-opioid activity. Therefore it is reasonable to suppose that neurophysiological activity of the isolated fraction is due to the peptides formed on enzymatic hydrolysis of proteins in vivo rather than these proteins as such.     

Regulation of beta-galactosidase synthesis in Escherichia coli by exogenous cyclic 3',5'-adenosine monophosphate]

The effect of cyclic 3',5'-adenosine monophosphate (cAMP) on the rate of beta-galactosidase biosynthesis was studied in the cells of Escherichia coli M-17 growing in MPB and mineral media with glucose and maltose, i.e. under the conditions of various catabolite repression, as well as upon lac-operon induction by isopropyl-beta-D-galactopyranoside (IPGP). The stimulating action of exogenous cAMP was found only in a medium with salts and glucose. The induction by IPGP was highest during the growth in a medium with glucose and maltose. When the medium contained IPGP, cAMP accelerated the enzyme synthesis in all media, but only at the early growth phases, while cAMP eliminated the effect of IPGP at the stationary phase of growth. The regulation of beta-galactosidase biosynthesis by cAMP demonstrated for the first time that this effect depended on the physiological state of E. coli: the expression of catabolite-sensitive E. coli genes was subject to both positive and negative regulation in one and the same inducible system. The effect exerted by cAMP depended on the nature of a carbon source in the growth medium.     

An electron microscopic study of the intercellular contact of a vaccinal strain of Francisella tularensis with gram-negative and gram-positive bacteria

The use of transmission electron microscopy (the negative contrast and ultrathin section techniques) has made it possible to show that F. tularensis vaccine strain is capable, under normal conditions and in mixtures with other gram-negative and gram-positive bacteria, of forming cell aggregations with close contacts between cells, this contact being probably irreversible. The ultrastructure of bacteria taking part in the formation of intercellular contacts remains intact.