[Macromolecular synthesis and cell division in Escherichia coli in the lag-phase of diauxie]. / Sintez makromolekul i delenie kletok u Escherichia coli v lag-faze pri diauksii.

The pulse incorporation of radiolabelled mannitol, glycerol, thymidine, uridine and protein hydrolysate has been studied during the Escherichia coli growth. The incorporation of carbohydrates and predecessors is sharply changed before and after lag-phase, that is due evidently to the partial synchronization of cell population. Three cell divisions have been found: before lag-phase (determined by the curve of optical density), at the end of it and after it termination. Cell division is accompanied by removal of catabolic repression from glycerol utilization, by increase of protein, RNA and DNA synthesis rates. The rates of biopolymer synthesis decrease sharply at the beginning of lag-phase, but DNA synthesis is going on at a rather high level.

[Development of catabolic repression during Escherichia coli growth on a carbohydrate mixture]. / Issledovanie razvitiia katabolitnoi repressii pri roste Escherichia coli na smesi uglevodov.

During the cell growth with mixture of three sources of carbon (mannit-arabinose-glycerol, glucose-sorbite-glycerol, glucose-sorbite-galactose) the components of the mixture have been found to be utilized in series. After using up the first, the repression is eliminated unselectively in utilization both the second and the third. Then after the lag-period the utilization repression of the third carbon source by the second one occurs. The phenomenon of "remaining repression" consisting in that at the cell growth with mixture of mannite and sorbite after using up the first carbohydrate the cells cannot start utilizing the second has been described.

[Dynamic aspects of RNA metabolism in the brain of mollusca during electrical effects]. / Dinamicheskie aspekty obmena RNK v gangliiakh molliuskov pri elektricheskikh vozdeistviiakh

The dynamics of RNA and protein metabolism (as indicated by the incorporation of labeled precursors) during electrophysiological 'learning" and electrical stimulation of isolated ganglia of the snails Tritonia diomedia and Helix pomatia has been investigated. 'Learning" phenomenon manifested itself in the maintenance of synchronous discharges in the electrical activity of the neurons after cessation of the stimulus. At all the electrical stimulations, fast periodic processes of accumulation-degradation of RNA and protein were observed. Radioautographic studies indicate that these processes begin at first in the glia and then in the neurons. The pattern of incorporation of the precursor into the protein is similar to that into RNA, indicating that short-living RNA is involved into the synthesis of short-living proteins. Aurantin (a mixture of actinomycines) inhibits glial synthesis of RNA to a greater extent than neuronal one,-both at rest and electrical stimulation. On the other side, aurantin hinders or even completely blocks "learning" phenomenon. It is suggested that normal RNA metabolism is necessary for the formation of trace phenomena. No essential differences in the metabolism of RNA, protein and nucleotides were found during "learning" and stimulation.