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

An account is given of the "oxygen theory" of biomagnetic effects, whereby molecular oxygen is the primary, elementary, and fundamental material affected by the influence of a permanent magnetic field (PMF). The ability of a PMF to alter inductively the motion of paramagnetic O2 dissolved in a fluid, and to uncouple it from other substances which participate in oxidative processes leads, first of all, to a disturbance of O2 transport and to a disturbance of cellular bioenergetic processes. A series of biomagnetic effects are explainable on the basis of the suggested mechanism. Experimental data regarding changes in pO2 in tumor tissue under the influence of a PMF, and data concerning the inhibition of growth of reinoculated tumors (Pliss' lymphosarcoma and RS-1) under the combined influence of PMF and hypothermia, are given as indirect support of the oxygen mechanism of PMF effects and the oxygen-peroxide mechanism of carcinogenesis.

Questions of the identification of the type of pharmacological activity of physiologically active substances (PAS) with a receptor type of action under conditions of screening are examined. IN accordance with current concepts of the theory of the recognition of modes, the type of action of PAS was identified by establishing a set of criteria ("vectors of modes") characteristic of the effect of known substances and by selecting methods of comparing them with the vectors of the modes of the compounds being tested. Test parameters recorded by the the functional multiparametric method permitting identification of the type of the effects and an evaluation of their quantitative manifestations with the framework of a single experimental approach were used as the unknown set of criteria. The method of describing the relative change in the parameters from the dose as the vectors of action was used and the function of proximity (similarity).

Changes in the rheoencephalogram (REG) obtained for cosmonauts on the first and second expeditions during their time aboard the orbiting station, Salyut-4, are described. REGs were recorded by a small apparatus, Levkoi-3, with subsequent transmittal of the information to Earth stations. It was established that during flight under conditions of negative pressure on the lower half of the body (NPLHB), there was a decrease, in all cases, in pulse filling of brain blood vessels and an improvement in venous outflow from the cranial cavity. This indicates the efficiency of the compensation-adaptation reaction of the system studied to the state of weightlessness and the positive effect of prophylactic measures taken during flight. REG changes in indices affected by negative pressure were mainly such as were observed in preflight investigations, but there were individual differences. It was discovered that in all cosmonauts during performance of functional tests on a veloergometer, there was a significant increase in indices of pulse filling of brain blood vessels in response to muscle load in comparison with preflight studies. Normalization of basic REG indices took 3-7 min after the work was concluded. Planimetric analysis with REGs registered under conditions of long flight disclosed a variety of reactions of different sections of the vascular channels in the brain. Data obtained indicated the value of the REG method for making observations on crew members of space ships during orbital flights.

The reaction of thymocytes to hypoxic stress has been investigated according to indices of nucleic acid exchange. Acute and moderate, though long-term, hypoxia noticeably depresses DNA and RNA syntheses in rat thymocytes. Activation of nucleic acid repair synthesis during restoration of the organ takes place only if the hypoxic effect alternates with periods of normoxia. Under conditions of continuous prolonged hypoxia (high altitude), the adaptation is achieved by a decrease in thymocyte nucleic acid exchange. The role of thymocytes in the homeostasis-maintaining mechanisms, as the organism becomes adapted to hypoxia through different training conditions, is discussed.

Description is provided of conditions selected for the study of protein amino groups (AG) on the external surface of rat erythrocyte membranes (EM) by means of 2,4,6-trinitrobenzenesulfonic acid (TNBS). The number of protein AG reacting with TNBS was influenced by the season of the year, the physiologic state of the donor animal, and other factors known to alter EM. It appears that structural perturbations introduced by these factors into EM are responsible for alterations in the accessibility of the protein AG to TNBS.

The possibility of complete degradation of DDT by Pseudomonas aeruginosa 640x was demonstrated in principle. A study of the conditions of degradation of DDT by this culture was made. It was demonstrated that only dechlorination of DDT to DDD is accomplished without addition of a supplementary substrate. The rest of the processes right up to the formation of benzhydrol and phenylacetic acid take place only under conditions of cometabolism. For dechlorination of the aliphatic fragment of DDT and the aromatic rings, anaerobic conditions, nitrates in the form of electron acceptors, and calcium lactate as a cosubstrate are preferred. Degradation of nonchlorinated benzophenone takes place only under aerobic conditions with glycerol as a cosubstrate. Phenylacetic acid and benzhydrol are used by the culture as sole sources of carbon; aerobic conditions are necessary for their degradation. On the basis of analysis of decomposition products of DDT and a study of the pathways of degradation of its metabolites and analogs, a means of converting DDT by P. aeruginosa 640x is proposed.

The literature data on toxins of neuroparalytic action, produced by pyrrophytic algae and capable of being accumulated by edible mollusks, are presented. The LD50 for mice of saxitoxin, the best known and most strongly acting toxin, is 5-10 microgram/kg. some toxins of dinoflagellates have been isolated in purified form. Their physicochemical properties have been studied and the structural formula of crystalline derivatives of saxitoxin has been established. The major problem of environmental protection is associated with a study of toxic dinoflagellates.

The causes of heavy losses in storage of harvested crops of potatoes, vegetables, and fruits are considered, and the means of preventing them under modern farming conditions are discussed. Primary attention was directed towards the results of work devoted to the study of biochemical mechanisms which control the resistance of plant tissues to phytopathogenic microorganisms, the state of quiescence and transition to active growth, ripening and ageing, as well as methods of operating these mechanisms in order to protect harvested crops against infectious diseases and functional disorders, premature sprouting and overripening. The necessity is substantiated by combining various methods: active ventilation, artificial refrigeration, controlling gaseous medium, physiologically active substances, ionizing radiation, and other factors, since methods which protect from one source of losses can facilitate the development of other kinds of losses. Of crucial importance is the utilization of the resistance mechanisms of the plant tissues themselves.

A clear correlation was found between the growth of mutant forms of pea plants and the light intensity: With an increase in the latter the growth of the plants was inhibited and the rate of photosynthesis increased. The inhibitory action of light on stem growth affected not only tall pea plants, but also dwarf forms. A definite link was observed between the genetic apparatus and the balance of endogenous phytohormones and inhibitors. The content of bound forms of gibberellins was directly related to the growth intensity--the content of these substances was highest in the tall Torsdag pea plant, it was lower in the semidwarf K-29, and it was very low in the dwarf K-202. The content of quercetin glucosylcoumarate was lowest in Torsdag pea plants, in dwarf mutants the greater the amount of this compound the shorter the stem. The genetically determined ratio of phytohormones and inhibitors in the original tall and dwarf forms of pea plants is retained under all illumination conditions at various intensities.

On the basis of numerous results of investigations on adrenergic systems, an orientational model of the adrenoreceptor (AR) is postulated. Its active center includes low-molecular-weight components--prostaglandins (PGE, PGF), steroids (cortisone, hydrocortisone), S+-adenosylmethionine, Ca, Mg, and Mn ions. Appraisal of the stereospecific characteristics of such a functional unit of AR explains the difference in the nature and magnitude of the effects of interaction of the catecholamines, their agonists and antagonists will the so-called alpha- and beta-AR. Depending on the organ or tissue in which the AR is located, its protein subunits comprise adenylcyclase (beta-AR) or Na,K-ATPase (alpha-AR). An obligatory component of the AR is catechol-O-methyltransferase. The model elaborated describes satisfactorily the molecular mechanisms of action of many pharmacological agents, explains why attempts to isolate and reconstruct the AR have proved fruitless, and gives grounds for rejecting the hypothesis that there exist steroid, prostaglandin, and purinergic receptors, linking the exceptionally high and diverse activity of these biologically active substances with their participation in adrenoreception among other reasons. A conception of the active centers of the AR as low-molecular-weight entities permits the explanation of such phenomena as the desensitization of the AR, the "interconversion" of beta-AR into alpha-AR with a change in the parameters of the medium, and certain components of the pathogenesis of bronchial asthma, etc.