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

It was shown that the structural damages arising in DNA-membrane complexes (DMC) of the Bacterium Bacillus subtilis under the action of gamma radiation are reversible in the postradiation period. The ability of the bacteria to repair radiation damage to DMC is correlated with their radiosensitivity. It is suggested that the process of restoration of the DMC depends on the products of the Pol A and the rec A genes.

The histochemistry of polysaccharides and proteins and the distribution of RNA were investigated in the glands and mature secretion of the anal sacs of the cat. Glycogen was extremely abundant in the epithelial lining of the lumen and efferent duct of the anal sac and also in ducts of sebaceous glands of the sacs constantly formed in the place of degenerating acini. Little glycogen was found in the unchanged sebaceous acini. The apocrine glands of the anal sacs were substantially richer in glycogen than the apocrine sweat glands of the skin and were in an active state. A high concentration of acid mucopolysaccharides was present in the mature secretion, and their source was the apocrine glands. The phases of the secretory cycle alternated in different cells and secretory portions of the apocrine glands highly asynchronously. Carboxylated acid mucopolysaccharides were more abundant than sulfated. Sialomucin, hyaluronic acid, and chondroitin sulfate could be identified in the secretion. Neutral and acid mucopolysaccharides were present in the mature secretion in the form of complexes with one another in approximately equal proportions; neutral polysaccharides consisted chiefly of glycogen. Besides polysaccharides, the apocrine glands produce large quantities of protein, in which the mature secretion was rich. This protein was predominantly basic, and the secretion contained very little acid protein. Maturing cells of the sebaceous acini, and also other specific sebaceous glands, were characterized by a much higher protein concentration than in ordinary sebaceous glands.

The peculiarities of the growth and extracellular accumulation of free keto and amino cids by a barotolerant culture (strain 0798) in culturing on Ran's glucose-mineral medium conditions of 1, 200, 300, and 500 atm were investigated. At a high pressure the culture possesses the ability for extracellular accumulation of free keto and amino acids, pyruvic, alpha-ketoglutaric, and oxaloacetic acids, alanine, and glutamic acid, while under conditions of atmospheric pressure, chiefly valine is accumulated in the medium, and there are no extracellular keto acids. The established specificity of the extracellular accumulation of keto and amino acids under conditions of high hydrostatic and atmospheric pressure is due to the different sensititivy of the enzyme systems participating in the biosynthesis of free keto and amino acids to the influence of high hydrostatic pressure.

As a result of investigations of the functional acitivty of eukaryote cells damaged by ionizing radiation and alkylating mutagens under conditions of extreme loading, the authors have suggested that natural aging and aging accelerated by mutagens are based on a process of accumulation of functional genetic damages. The molecular nature of these damages differs from the mutational changes and repairable damages of DNA.

In experiments on 159 sexually mature dogs with an average weight of 6.5 + 0.71 kg, a study was made of the dynamics of physiological indices (rectal temperature, respiration and heart activity) of heat stress and various (%) effects of damage depending on power density (500, 300, 100 mV/cm2) and duration of microwave irradiation (2400 MHz). On the basis of the data obtained, it was established that the relationship between power density and duration of microwave irradiation with an equally probable (0.1%) effect of damage may be interpolated (100 < power density < 500) by an exponential equation of the type y = 1416 x-0.8156, where y = power density, mV/cm2, and x is the time of irradiation in minutes. The probability characteristic of adaptation possibilities of functionally critical values of damage not exceeding the indeterminate probability is obtained.

Comparison was made of the rate of in vivo elimination from blood and organs of cattle of lymphocytes labeled with 3H-thymidine in the course of seven days in the norm and during lymphatic leukemia. Significant delay in the elimination of labeled lymphocytes, and especially of lymphocyte precursors, from the blood, spleen, and lymph glands of the animal was established in the stage of lymphatic leukemia that was examined.

Incubation of tissue of homogenates of peripheral nerves, liver, and subcutaneous adipose tissue of rabbits with [1-14C]palmitic acid and intraperitoneal injection of this preparation into rats, in a dose of 20 muCi per 100 g of weight of the animals, permitted establishment of the presence of enzyme systems of biosynthesis of n-alkanes in the tissues of higher animals. Evidence of the biosynthesis of n-alkanes in the animal organism represents a new aspect of our knowledge of the metabolism of this class of compounds in animal tissues.

The ATP and ADP content of planarians subjected to starvation for two weeks followed by feeding for the same period was investigated. The ATP and ADP content during fasting increased and then, after feeding, returned to normal. The ATP/ADP ratio varied in the same way, which is consistent with the view that the adenylic nucleotide pool is implicated in the regulation of the energy metabolism of the organism.

On the basis of fundamental investigations in radiobiology, numerous methods of using ionizing radiations in agricultural practice have been proposed. The current status of the problem, on the basis of basic, semi-production and industrial-scale tests of the suggested methods, is described. We conclude that there is now a satisfactory, economically viable radiation-biology technology. For wide introduction of this technology into agricultural practice, governmental decisions concerning the production of specialized equipment, training of service personnel and overall organization of the work under production conditions are required.