Biology bulletin of the Academy of Sciences of the USSR最新文献

It has been established that neurodystrophy resulting from the sectioning of an animal's left sciatic nerve and treatment of its central stump with formalin leads to a prolonged disturbance of the water- and salt-excreting function of the kidneys. As a rule, this is expressed as oligouria and decreased excretion of sodium in the urine. The indicated changes are due to disturbance of both intra- and extrarenal mechanisms. Intrarenal mechanisms of oligouria basically involve an acute depression in filtration of primary urine, and the hyponatriuresis is due to a decrease in the sodium load of the nephron and to an increase in the tubular reabsorption of sodium. Extrarenal mechanisms implicated in the indicated changes in sodium reabsorption involve an increased concentration of mineralocorticoid hormones of the body. Further studies have shown that the hyponatriuresis which arises during neurodystrophy is related not only to the increased concentration of the above-mentioned hormones in the fluid media of the body, but also is related to a change in the kidneys' sensitivity to them.

The alkaloid spectrum of the yellow horned poppy G. flavum was studied in early stages of development of this plant by methods of thin-layer chromatography and spectrophotometry. It was established that gradual formation of the alkaloid complex takes place in parallel with growth differentiation of the organs during seed germination and the formation of seedlings, which is due to the de novo biosynthesis (in a specific sequence) of alkaloids of various structural types: first 1,2,9,10-substituted aporphines, then protopines, and, finally 1,2,10,11-substituted aporphines, benzophenanthridine, as well as morphinans. It was found that glaucine predominates among the alkaloids of the seeds and in the above-ground organs of seedlings of different ages, while protopine predominates in the subsoil organs. The data obtained on the nature of the formation of the alkaloid complex suggest that the aporphines are the phylogenetically oldest compounds among alkaloids of other groups of this plant.

A cytogenetic analysis of variants of Fisher mouse lymphadenosis L-5178 resistant to the antitumoral antibiotics bruneomycin and rubomycin C showed that the cytogenetic characteristics of the changes in the tumor cell population correlate with the chemotherapeutic indices of the development of drug resistance. Cytogenetic and kinetic analyses showed that variants of Fisher lymphadenosis L-5178 resistant to bruneomycin and rubomycin C retain sensitivity to N-nitrosomethylurea (NMU). The activity of NMU in an experiment on resistant substrains of lymphadenosis can serve as a basis for the clinical use of NMU in the treatment of lymphomas resistant to antibiotics.

Four experiments were carried out with mammals (white laboratory rats) in Kosmos biosatellites. The experimental results indicate that rather prolonged weightlessness does not cause pathological changes in internal organs. Changes were discovered in the metabolic and hormonal status of the organisms, allowing us to consider an 18-22-day space flight as a moderately stressful activity. Changes in the musculoskeletal system involved atrophy of particular muscle groups, adaptive transformation of the contractile properties of some of them, osteoporosis, and decreased durability of bony tissue. There was a decrease in the ATPase activity of myocardial myosin, and there were changes in the erythrocytic system: decreased erythrocytic hemopoietic activity, increased levels of spontaneous hemolysis of erythrocytes, etc. All the described changes were reversible, and examination of the animals 25 days after their return to Earth showed practically complete normalization of the parameters studied.

Changes in DNA after heating of human cells at 43.5 and 44 degrees C were found for the first time by means of sedimentation in an alkaline sucrose gradient. These changes are probably mainly determined by three processes: the appearance in DNA of alkali-labile bonds, the formation of stable DNA--protein complexes, and changes in the superstructure of the DNA, in particular partial unfolding of the nucleosomes. The existence of a mechanism for nonexcision repair of thermal lesions in DNA by an enzyme ("repurinase") catalyzing the formation of a glycoside bond between the base of a purine precursor of DNA and the deoxyribose residue of an apurine component is suggested.

Electron microscopy and morphometric studies were made of apical meristem cells of a shoot of wheat (Triticum aestivum L., variety Saratovskaya-29) at various phases of ontogenesis: vegetative, prefloral, and beginning of flowering (from seed embryo to the beginning of formation of the head). It was demonstrated that during this period there are changes in cytoplasmic structures, their number, proportions, and internal structures. Changes were disclosed which were linked to the hereditary course of growth and differentiation of the apex, that is, changes that were evidently ontogenetic (dynamics of lipid drops, of the Golgi apparatus, endoplasmic reticulum, and to some degree, the structure of plastids and mitochondria). It was demonstrated that in the course of the vegatative phase, changes in activity of the apex meristem and its various zones are connected with comparatively small quantitative changes in content of basic organelle cytoplasm, and their structural transformations are more significant. The activation of the apex in the pre-floral phase is linked to an increase in formation of membrane systems, increase in the functional activity of organelles, and increase in the formation of ribosomes and their density in the cytoplasm which provides conditions for a transition of the apex to generative differentiation.

Elaboration in rats of a local motor-food conditioned reflex in the form of pressing a lever by a preferred foot was accompanied by an increase of the protein content in interneurons in the absence of a change of this index in large and medium pyramidal neurons in the V layer of the motor cortex in the projection of the preferred foot in comparison with the symmetric point of the opposite hemisphere. Reconditioning of the conditioned reflex, i.e., its accomplishment by the nonpreferred foot, was accompanied by a decrease of the protein content in large pyramidal neurons of the V layer of the motor cortex in the absence of changes in the dry mass of interneurons in the projection of the nonpreferred foot in comparison with the projection of the preferred foot. Pyramidal neurons of the III layer reacted by an insignificant change in the protein content both in the case of elaborating the conditioned reflex and reconditioning of its effector component. It is suggested that the pyramidal neurons of the III layer, large pyramidal neurons and interneurons of the V layer of the motor cortex are involved in metabolic provision of elaboration of the local motor-food conditioned reflex and in the formation of new motor coordination at different stages of these processes.

The problem of quantitative evaluation of the pharmacological influence of physiologically active substances with receptor action on the organism under conditions of screening is discussed. A vector-significant criterion, based on a functional multiparameter method (FMM), is suggested as the basic characteristic of effectiveness of action. This criterion permits an evaluation of the latitude of the permissible physiological effect, the threshold of subtoxicity, and the selectivity of the action of the substance according to the dominant activity.

The importance of K. E. Tsiolkovskii's ideas in the formation and development of space medicine is argued. The author analyzes K. E. Tsiolkovskii's science fiction writings and his basic researchs in aerodynamics and rocket techniques and shows that, besides the technical aspects of the problem, Tsiolkovskii penetrated deeply into the nature of the biological phenomena and revealed their essentials in a series of short descriptions. Tsiolkovskii argued convincingly in support of the view that man can withstand the action of factors of space flight and, step by step, can conquer cosmic space.

It has been established by methods of spectrophotometry and spin probe that the organophosphorus pesticide metaphos, widely used in practice, is an inhibitor of NADH2 oxidase of the respiratory chain of the mitochondria and exerts an influence on the structural organization of the mitochondrial membrane. An effect of metaphos on the nature of the distribution and kinetics of NADH2-induced death of monoradical spin probes of various chemical structures was detected in a suspension of submitochondrial particles obtained from beef heart.