Biomedical subjects
Publications and source records attributed to L V Vitvitskaia.
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The incorporation of [3H]thymidine into DNA and of [14C]uridine into RNA has been investigated in different areas of brain and in liver of inbred August rats, non-inbred Wistar rats and hybrids between male wild-type and female Wistar rats which were kept either under normal conditions or under intensive sensory stimulation at different age. DNA metabolism has been found to display tissue, regional, age-dependent and interlinear differences. Sensory stimulation influences considerably the synthesis of nucleic acids which is maximal at early ontogenesis stages and in the brain of hybrid animals.
The effect of intense motor activity (swimming) followed by signs of physiological stress, on biosynthesis and phosphorylation of membrane proteins from different brain cells (neurons, glia) and sections (cerebellum, brain stem) as well as from liver, involved a significant decrease of 14C-methionine and 32P-phosphate incorporation related, probably, to inhibition of the physiological function, in all the electrophoretic fractions of proteins. In membrane proteins of cortical cells (particularly neurons), on the contrary, there was an increase of biosynthesis and phosphorylation in all the fractions. This seems to reflect an activation of cortical neurons for adaptation purposes.
Stimulation of salmon larvae by electric current led further to unstable character of reactions in the open field. Acoustic stimulation both by tonal and musical signals favourably influenced the behaviour in the open field and the ability to elaborate conditioned reflexes. Changes of the content of nucleic acids were not found in the brain tissue but were found in the muscles, where they correlated with the growth speed and motor activity of the experimental fishes. The obtained data show the possibility of elaboration of applied methods of the control of CNS development and behaviour of young fishes at fishing plants.
On example of wild and hatchery (cultivated in ponds and pools) young Russian sturgeons and white salmons, it is shown that fishes cultivated in more complicated ecological conditions (in natural reservoir in comparison to artificial and in ponds in comparison to pools) have greater sizes of CNS structures connected with the development of the analyzer leading in the life of this species (the midbrain--in white salmon, the forebrain--in sturgeon) and are characterized by a higher content of DNA in the brain and of RNA at the unit of DNA. This testified to more intensive processes of replication and transcription in CNS cells, more expressed manifestation of motor activity and higher parameters of elaboration and retention of a new habit. All this points to the necessity of enrichment of the medium in the hatchery reservoirs and the expediency of using of genetic-neurobiological criteria of hatching the young.
The content of nucleic acids (DNA and RNA) and proteins in 1 mg of tissue and RNA/DNA and protein/DNA ratio in different brain structures (the neocortex, the hippocampus, the cerebellum, the brain-stem), as well as in the liver was studied in rats at different stages of postnatal ontogenesis (25 to 55 days) in the norm, under ecological deprivation and in an information-enriched medium, involving elaboration of conditioned reflexes. It was shown that intense physiological function of the brain cells in an information-enriched medium is attended with substantial enhancement of the RNA/DNA ratio, i.e. stimulation of transcribing activity of the cells genome. In conditions of ecological deprivation this value at first slightly increases, and the significantly diminishes in all the studied brain structures. Protein content in the nerve tissue is more stable in ontogenesis and changes but slightly at different afferentation levels. No significant changes were observed in any of the studied parameters in the lever tissue.
The intensity of 3H-thymidine incorporation in DNA, as well as DNA content of the liver, brain stem, cerebellum, and neocortical tissues have been investigated in 1-32 days old rats. It was shown that the kinetics of the studied parameters is principally different in the tissues investigated.
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The fractional composition of chromatin proteins of various morphological structures and areas in the rabbit and human brain was studied by means of electrophoresis in polyacrylamide gel with sodium dodecyl sulphate at different stages of pre- and postnatal ontogenesis. Both the species are characterized by differences in the set of chromatin proteins between different brain structures (regional heterogeneity) arising and increasing during ontogenesis. The heterochronism was found in the appearance of a number of high molecular weight fractions of chromatin proteins suggesting the advanced development of genetic apparatus of the phylogenetically ancient brain structures. The human brain, unlike the rabbit one, is characterized by individual differences augmenting during ontogenesis.
The fractional factorial analysis of 2(5) type was carried put in order to estimate the influence of 5 different factors on stellate sturgeon fry behaviour in early ontogenesis. Different indices obtained in hydrodynamic test, in "open-field" test, in passive avoidance conditioning procedure were analysed. Statistically significant positive and negative influences on the indices were found for all the factors (level of illumination, food diets, high or low stream, presence or absence of predator fishes, character of a bottom). The most probable mechanism of stellate sturgeon behaviour modifications under the influence of different factors is the selection (predominant survival) of the samples which possess peculiarities the most adequate to environmental conditions.