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N V Nechaeva

Publications and source records attributed to N V Nechaeva.

At least 19 recordsLinked to original sources
PubMed2000

Ganglioside-mediated metabolic synchronization of protein synthesis activity in cultured hepatocytes.

An ultradian oscillation of protein synthesis was detected by synchronization of metabolic activity in rat hepatocyte cultures. This oscillation occurs in dense cultures in fresh medium, but not in sparse ones. Metabolic synchronization of sparse cultures, however, was initiated by conditioned medium or addition of 0.3-0.5 microm of a mixture of bovine brain gangliosides to fresh culture medium along with either 0.06-0.2 microm GM1 or 0.1-0.2 microm GDIa. GTIb and GDIb did not produce oscillations, nor did human liver ganglioside GM3. High expression of GM1 ganglioside determinants in hepatocytes maintained in the conditioned medium purified polyclonal antibodies to GM1 was coupled with protein synthetic oscillatory activity, i.e. metabolic synchronization. Incubation of dense cultures with GM1-antibodies for 24 h decreased the amplitude of these oscillations. In sparse cultures maintained in fresh medium where protein synthesis showed no oscillatory pattern, GM1 expression was low.

Activity Cycles↗
PubMed1992

The rhythm of protein synthesis does not depend on oscillations of ATP level.

A rhythm of the [3H]leucine incorporation rate with a period of about one hour (circahoralian rhythm) has been found in rat hepatocytes grown in vitro as a monolayer and in liver organ culture. The periodicity of the incorporation rate remained after correction for changes in leucine pool size. A similar periodicity of the leucine incorporation rate was detected in a cell-free system prepared from rat hepatocytes. We have also found circahoralian oscillations of the ATP level and similar oscillations of the leucine tRNA aminoacylation rate in a hepatocyte monolayer. The addition of 1 mM ADP to the culture resulted in a considerable increase in the ATP level in the cells, but the rhythm of protein synthesis was retained under these conditions. The conclusion that there is a flexible association between changes in the ATP and GTP levels on the one hand, and oscillations of the protein synthesis rate on the other, is also supported by experiments with a cell-free system, in which the rhythm of protein synthesis rate was observed in the presence of excess ATP and GTP. We propose an hypothesis to explain the fractal pattern of circahoralian metabolic rhythms.

Adenosine Triphosphate↗
PubMed1987

[Effect of a pH change in the medium and cytoplasm of cultured cells on the rhythm of protein synthesis].

A circahoral rhythm of protein syntheses similar to that in monolayer hepatocytes was discovered in cell culture of Chinese hamster fibroblasts. Studies on the effects of pH changes in the culture medium and cultured cells on different parameters of protein synthesis showed some pH-dependent changes of predecessor pool and of its incorporation intensity into proteins. At the same time changes in a relative incorporation of the predecessor into proteins (with a correction for the pool) were insignificant. This value characterizing the productivity of protein synthesis does not seem to be directly associated with pH changes in the cells. The mean period of the rhythm of protein synthesis and intracellular pH was not changed with medium pH alterations.

Animals↗
PubMed1984

[Possible role of ornithine decarboxylase in controlling the hourly rhythm of protein synthesis].

A study was made of the effect of non-competitive inhibitors of ornithine decarboxylase (1,3-diaminopropane and cadaverine) on the circahoralian rhythm of protein synthesis in liver sections incubated in vitro. Addition of diamines to the culture resulted in a decrease in the amplitude of protein synthesis fluctuations and in some cases in an almost complete rhythm wearing. It is suggested that diamines affect the rhythm of protein synthesis by inhibiting the key enzyme of polyamines--ornithine decarboxylase.

Animals↗
PubMed1983

[Changes in ornithine decarboxylase activity in the developing parotid salivary gland].

Ornithine decarboxylase activity in the rat parotid salivary gland was estimated during the early postnatal development. Regular alterations of enzymatic activity were found in different periods of gland development. The data obtained were compared with the evidence on the establishment of protein synthesis circahoralian rhythm of this organ in ontogenesis. The ornithine decarboxylase activity, being rather high in the parotid gland as long as up to the 20th-21st days, decreases during the termination of differentiation in this organ. It rises simultaneously with the emergence of circahoralian rhythm of protein synthesis.

Aging↗
PubMed1983

[Correlation of the rhythms of protein synthesis and secretion in a hepatocyte monolayer culture].

In primary monolayer culture of hepatocytes, circahoralian rhythms of protein synthesis and secretion were discovered. In one of the hepatocyte populations the rhythmic cycle of protein secretion was found to be about twice as long as that of protein synthesis. Combination of different experimental variants such as the impulse and the long-term labelling of proteins or inhibition of protein synthesis, revealed that the secretion rhythms were predetermined by the secretion of both newly formed proteins and those stored in the cell for a long time. Upon the inhibition of protein synthesis with cyclohexeimide, the protein secretion in the monolayer changes its rhythmic pattern for a constant rate secretion. Possible causes of the alteration of circahoralian variations of protein synthesis are discussed.

Animals↗
PubMed1982

[Circahoral fluctuations in protein release from hepatocytes in a monolayer culture].

An account is presented on morphological and functional properties in primary monolayer culture. Advantages of this model, as compared to the suspension cells, for studying various aspects of the liver vital activity are described. Dynamics of protein secretion by hepatocytes during a 2-hour period was investigated by different methods. The data obtained point to cyclic changes of the rate of protein secretion in the liver cells with circahoralian periodicity, which is typical of the changes in the rate of protein synthesis we revealed earlier for the same cells.

Animals↗
PubMed1980

[Role of polyamines in regulating the circahoral rhythm of protein synthesis in the cell].

Effect of putrescine added to the cultural medium on the cellular rhythm of the protein synthesis rate in parotid gland slices and isolated hepatocytes of the rat was studied. Addition of putrescine, a product of ornithine decarboxylase-catalyzed reaction, led to the inhibition of protein synthesis rhythms both in the slices and isolated cells. These data suggest the participation of polyamines in maintaining the circahoralian rhythms of protein synthesis.

Animals↗
PubMed1979

[Approximately hourly rhythm of 3',5'-cAMP in rat parotid gland slices].

3',5'-CAMP concentration in rat parotid gland slices indubated in vitro for 12-14 hours was measured by radioimmunoassay. Clices for determination of cyclic nucleotide concentrations were taken at 10-minute intervals over a period of 2 hours. All slices used in a specific experiment originated from a single gland. Rhythmic changes in 3',5'-cAMP concentration in the rat parotid gland were found. The period of these changes (20-50 min) was similar to that of fluctuations in other parameters, such as dry weight, the rate of protein synthesis and ornithine decarboxylase activity, described for the same system elsewhere.

Animals↗
PubMed1979

[Rhythm of protein concentration and incorporation of 3H-lysine into hepatocytes in vitro].

"In vitro" incubated slices of the rat liver, by the method of interferometry combined with radioautography, have demonstrated hour's rhythmic fluctuations in protein concentration and 3H-lysine incorporation into proteins. The biochemical method has demonstrated fluctuations in protein synthesis rate in the same cells with an average period of about one hour. The possibility to apply the interferometric method in combination with radioautography for revealing quantitative changes of protein in slices of organic cultures is demonstrated.

Animals↗
PubMed1978

[Rhythm of ornithine decarboxylase activity in slices of rat parotid gland].

Ornithine decarboxylase activity and the rate of protein synthesis were measured in the rat parotid gland slices incubated in vitro. A circahoralian rhythm of the enzyme activity preceding by phase that of the protein synthesis was found. These data are consistent with the assumption that ornithine decarboxylase may participate in the maintenance of the protein synthesis circahoralian rhythm in the parotid gland cells.

Animals↗