Isolation of Escherichia coli K12 mutants with deficient in precise excision of transposons

Plasmid pNM1, the derivative of R100.1, has been constructed by insertion of transposon Tn5 into structural tet genet (Tn10) of the parental plasmid. The frequency of precise excision of Tn5 from plasmidic genome is 10(-5). The high frequency of precise excision obtained in this system permits one, to use it for isolation of mutants having low frequencies of precise excision. Two mutants were isolated in which the frequencies of precise excision of Tn5 were decreased for two orders. The pex1 and pex2 mutations responsible for the effect decrease the precise excision of Tn5 from R100.1 as well as from RP4 genomes.     

Interaction of cholesterol-conjugated alkylating oligonucleotide derivatives with cellular biopolymers.

Interactions of oligonucleotide derivatives with mammalian cells and cellular biopolymers have been investigated. The derivatives were oligonucleotides bearing an alkylating 2-chloroethylamino group at the 3'-end and a cholesterol residue at the 5'-terminal phosphate. These compounds are readily taken up by cells and react with cellular DNA, RNA and some proteins which may play a role in delivery of the compounds into cells.     

Cooperation of Hepatocytes in vitro in the Rhythm of Protein Synthesis is Promoted by the GM1 Ganglioside Contained in Vesicles and Liposomes

The medium conditioned by dense, self-synchronized hepatocyte cultures was centrifuged at 150000 g to obtain two fractions. The light fraction (supernatant fluid) contained ganglioside monomers and micelles, and the heavy fraction (pellet) contained gangliosides in the vesicles shed from the cell membrane. In the test populations of hepatocytes, the rhythm of protein synthesis was used as an indicator of cell synchronization resulting from their cooperative activity. Diluted hepatocyte cultures with asynchronous fluctuations of protein synthesis proved to be synchronized by both the initial conditioned medium and its vesicular fraction. Our previous studies have shown that this occurs under the effect of GM1 monosialoganglioside, which is released from cultured cells and accumulated in the conditioned medium. Liposomes consisting of GM1 and phosphatidylcholine from egg yolk (1 : 19 mol%), compared to free exogenous GM1, synchronized the rhythm of protein synthesis more effectively: synchronization was observed at a GM1 concentration in liposome suspension of only 0.0003 M, compared to 0.06 M and higher in the case of free GM1. Thus, GM1 as a component of membranes and monolayer lipid structures proved to be much more effective than free GM1 in promoting hepatocyte cooperation with respect to the rhythm of protein synthesis.     

The effect of inoculation with <Emphasis Type="Italic">Rhizobium leguminosarum</Emphasis> on the contents of cytoplasmic protein and free amino acids in the roots of pea seedlings

The changes in the contents of protein and free amino acids in pea plants inoculated with Rhizobium leguminosarum were studied taking into account the susceptibility of roots to root nodule bacteria. The content of cytoplasmic protein during infection increased in the actively growing root zone (0–5 mm) and decreased in the root zones susceptible to rhizobia (5–20 mm from the root tip). The quantitative composition of free amino acids changed essentially upon inoculation of pea seedlings with R. leguminosarum.     

The effect of inoculation with Rhizobium leguminosarum on the contents of cytoplasmic protein and free amino acids in the roots of pea seedlings

The changes in the contents of protein and free amino acids in pea plants inoculated with Rhizobium leguminosarum were studied taking into account the susceptibility of roots to root nodule bacteria. The content of cytoplasmic protein during infection increased in the actively growing root region (0-5 mm) and decreased in the root regions susceptible to rhizobia (5-20 mm from the root tip). The quantitative composition of free amino acids changed essentially upon inoculation of pea seedlings with R. leguminosarum.     

The effect of nuclear dyes on the frequency of aberrations in mucosal cells of humans

The effect of staining with commonly used nuclear dyes (orsein, light green, methylene blue, azure-eosin by Romanovsky-Giemsa) on the frequency of occurrence of nuclear disorders (micronuclei, perinuclear vacuoles, notches, protrusions, such as "tongue" and "broken egg") in human buccal mucosa was determined. It is shown that Romanovsky-Giemsa dye is the best type of dye both in the quality of the micropreparations and the spectrum of detected abnormalities.     

Effect of brain and thymus cationic proteins on membrane permeability]

Cationic proteins of brain lysosomes (LCP), myelin (MCP) and nuclear histone fractions from calf thymus (T) and rat brain (B) are shown to increase at different degree the permeability of brain lysosomes and neutrophiles for acid RNAase, acid phosphatase, catepsin D and beta-galactosidase. According to the effectivity, basic proteins can be listed in the following order: for lysosomes-f2aT, F3B, f3T greater than total histones B, f2bT greater than f2B greater than LCP, MCP greater than flT, flB; for neutriphiles-f3T larger than or equal to total histones B larger than or equal to f3b MCP larger than or equal to f2aT, f2bT greater than f2B greater than LCP greater than flB greater than flT. Fractions f2a and f3 considerably increased the release of acid RNAase from lysosomes in very low concentrations beginning from 0,2 mug/ml, while the release of catepsine and acid phosphatase took place beginning from 5-10 mug/ml. The effect of lysosome and myelin cationic proteins on the release of hydrolases occurred at concentrations ten to hundred times higher.