[Survival rate of Leptospira pomona in the soil at a natural leptospirosis focus]. / Vyzhivaemost' leptospir serogruppy pomona v pochve prirodnogo ochaga leptospirosa.

At the area of a natural focus of leptospirosis (caused by L. pomona) in the Mozdok region of the North Occetic ASSR leptospires were detected by the method of dark field microscopy in 22% of intact soil samples. The presence of pathogenic leptospires in this soil was not confirmed by the method of the biological assay on Syrian golden hamsters. In controlled tests lasting 1-277 days, in 30.4% of cases L. pomona retained their viability, pathogenic and antigenic properties for as long as 74 days, while staying in the soil at the focus of infection with humidity being 15.2-31.4% and pH = 6.7-7.2. 11 Leptospira cultures isolated after staying in the soil retained their pathogenic properties and the death of the animals used in the bioassay from the acute form of leptospiral infection.

[The noncorrespondence of the geographic ranges of the host and the causative agent]. / O nesootvetstvii arealov khoziaina i vozbuditela.

For the first time the experimental and field studies of Leptospira infections, carried out over the period of 6 years, have revealed that the habitat of striped field mice (Apodemus agrarius Pallas 1778) serving as a host for Leptospira pomona, serovar mozdok, is much wider than the habitat of the infective agent proper. The presence of an animal species highly sensitive to a definite leptospiral serovar and serving as its reservoir at a given locality cannot be regarded as a proof of the presence of the epizootic process without bacteriological confirmation. But, in the absence of homologous Leptospira carriage, intensive leptospiral seroconversion can be attributed to a population other than that of the host.

[The functioning of a drained natural focus of leptospirosis in a nonchernozem area]. / Funktsionirovanie osushennogo prirodnogo ochaga leptospirozov v Nechernozem'e.

The drainage of a natural focus of leptospirosis of the flood plain-swamp type, carried out over the period of 15 years, has led to changes in the species structure of small mammals and to an increase in the number of Leptospira-carrying species. Nevertheless, like before drainage, the prevalent species and the main carrier of leptospires is still the root vole (Microtus oeconomus Pallas). The intensity of the epizootic process among small mammals at the final stage of drainage has proved to be similar to that at the initial stage. At the same time the cultivated fields created on the drained territory of the natural focus abound, by the time of harvesting, with small mammals among whom the intensive epizootic process takes place.

[Differences in the susceptibility of field mice from the Altai Territory and Moscow Province to Leptospira of serovar mozdok and serogroup Pomona]. / Razlichiia v vospriimchivosti polevykh myshei Altaiskogo kraia i Moskovskoi oblasti k leptospiram serovara mozdok serogruppy Pomona.

Adult striped field mice (Apodemus agrarius) caught in the Altai region proved to be insusceptible to experimental infection when inoculated with Leptospira of serovar mozdok, serogroup Pomona. In pregnant females, though infected with this organism, no leptospiruria was observed. At the same time nonpubescent animals became Leptospira carriers, females becoming carriers 4.5 times more frequently than males. The formation of antibodies to Leptospira in the test rodents was poorly pronounced and did not depend on their sex, age, physiological state and the presence of renal leptospirosis. But all adult striped field mice belonging to the population of the Moscow region became Leptospira carriers in such experiments.

[Repair of membrane damage caused by low temperature freezing of E. coli cells]. / Izuchenie reparatsii povrezhdenii membrannogo apparata, vyzvannykh nizkotemperaturnym zamorazhivaniem kletok E. coli.

Low temperature freezing of E. coli cells causes an almost complete cell damage. A transfer of the frozen cells to nutritional media results in a repair of some of the damages, i.e. in reconstitution of the barrier stability of the E. coli outer membrane detected by a decrease in sensitivity of the frozen cells to the detergent and lysozyme action and in a change of the cell membrane potential measured by the penetrating ion method. The repair of the cytoplasmic membrane damage is followed by the changes in the permeability barrier for H+ and endogenous substrates, which results in restoration of ATP synthesis as a response to the artificial proton motive force and in an induction of beta-galactosidase synthesis. At the same time the synthesis of the periplasmic protein, alkaline phosphatase, in the cells after repair remains suppressed. An analysis of various biosynthetic processes demonstrated that the inhibition of lipid synthesis completely suppresses the reduction processes, while protein synthesis is not necessary for the repair. The importance of the transmembrane electrochemical proton gradient for the repair processed in E. coli cells was established; the ATP biosynthesis essential for the repair occurs, in all probability, via the glycolytic pathway and not via oxidative phosphorylation.

[Phospholipids of E. coli and activity of alkaline phosphatase]. / Fosfolipidy E. Coli i aktivnost' shchelochnoi fosfatazy.

The effects of liposomes prepared from the E. coli lipids on the activity of soluble alkaline phosphatase and on the complementation reaction between its subunits were studied. It was shown that the liposomes nonspecifically catalyze the dimerization of the enzyme subunits without changing the dimer activity. The effects of phospholipases A2 and C on the activity of membrane-bound alkaline phosphatase were studied. An interrelationship was found between the level of hydrolysis of membrane phosphatidyl glycerol (PG) by these enzymes and the changes in the activity of membrane-bound alkaline phosphatase. It was also shown that PG is less accessible to the effects of phospholipases in the cells with derepressed biosynthesis of alkaline phosphatase. It is assumed that the membrane PG interacts with the membrane-bound alkaline phosphatase during its translocation into the periplasm.

[Induction of E. coli alkaline phosphatase synthesis in cells preincubated at low temperatures]. / Indikutsiia sinteza shchelochnoi fosfatazy u E. coli preinkubatsiei kletok pri ponizhennoi temperatyre.

Cell preincubation at lowered t degrees was found to result in increased alcaline phosphatase synthesis. The ability of cells for increased alcaline phosphatase synthesis correlates with increased content of cis-vaccinic acid and higher liquidity of lipids. It has been ascertained that modifications caused by cell preincubation at lowered t degrees favour the greater stability of mRNA coding the alcaline phosphatase.

[Fatty acid makeup of Escherichia coli cells with repressed and derepressed phosphohydrolase biosynthesis]. / Zhirnokislotnyi sostav kletok Escherichia coli s repressirovannym i derepressirovannym biosintezom fosfogidrolaz.

Fatty acid composition of the cells of Escherchia coli wild strains K-10, and K-12 and the mutants of the regulatory genes for alkaline phosphatase was studied in conditions of repression and derepression of biosynthesis of phosphohydrolases. Derepression of phosphohydrolases was not accompanied with specific changes in fatty acid composition of the cells. An increase in the content of cyclopropanic acid in conditions of phosphorus deficiency and a decrease in the level of unsaturated fatty acids are related to deceleration of growth of the cells in these conditions.

[Phospholipid composition of E. coli cells and membranes under repression and derepression of alkaline phosphatase biosynthesis]. / Fosfolipidnyi sostav kletok i membran Escherichia coli v usloviiakh repressii i derepressii biosinteza shchelochnoi fosfatazy.

Lipid composition of E. coli membranes and cells in conditions of repression, derepression and constitutive synthesis of alkaline phosphatase is studied. The identity of qualitative composition of phospholipids and neutral lipids in these conditions is demonstrated. Derepressed and constitutive enzyme syntheses are correlating, a certain increase of phosphatidylglycerol in the total phospholipid pool being more pronounced in cells, than in membranes. The enzyme synthesis correlates also with the increase of 14C-label incorporation into lipids.