Characteristics of the range of mutations in nystatin resistance induced in yeasts by 6-N-hydroxylaminopurine

A simple procedure for induction of nistatin-resistant mutants in yeasts under the action of 6-N-hydroxylaminopurine (HAP) is proposed. Some differences between the spectra of mutations induced by HAP and UV-light are observed: HAP induces dominant and double recessive mutants more frequently.     

Osteogenic precursor cells in repair osteogenesis

Histological and electron-microscopic radioautographic investigations of regenerating medullar tissue were performed in rabbits following curettage. Low differentiated connective tissue cells were shown to possess the highest proliferative activity. DNA synthesis mainly took place in low differentiated, endothelial and osteogenic cells. It is suggested that low differentiated cells take part in histogenesis of regenerating medullar tissue, including osteo- and angiogenesis.     

Effect of retinoic acid on the aggregation of erythrocytes and leukocytes in the blood

Human and animal blood smear staining with PAPh has revealed mononuclear leukocyte-erythrocyte aggregates. Administration of retinoic acid increased concentration and dimensions of these aggregates and was followed by preferential accumulation of PAPh-negative osmotically unstable erythrocytes. Similar changes were detected in the blood samples of women engaged in the production of retinoic acid. Aggregate concentration showed positive correlation with erythrocyte sedimentation rate and no correlation with prothrombin time.     

Crystallins in the differentiation and regeneration processes of the crystalline lens in amphibia

The published and authors' data have been summarized on (1) the spectrum and properties of crystallins in different amphibian species, (2) localization and synthesis of crystallins in different cellular compartments of the adult amphibian lens, (3) dynamics of crystallin formation during embryogenesis and (4) lens regeneration from tissues of the larval and adult amphibian eyes. The necessity of more detailed studies of crystallin synthesis during embryogenesis and lens regeneration using molecular biological and biochemical methods is stressed. The significance of this approach is illustrated by the pioneering data of Soviet scientists on crystallin polypeptides and corresponding mRNAs in development of Rana temporaria obtained with the use of DNA-RNA hybridization and immunoelectroblotting.     

Chemoreceptor function and metabolism of the carotid body in the rat

Using fluorimetric and polarographic determination of cell respiration, metabolic reactions of the carotid body of rats to adequate stimulation have been revealed. Functional relationships of the dose--effect type, which were found for these reactions, may be approximated by equations which are similar to those describing the unconditioned reflexes from the carotid chemoreceptors. However, reactions of the metabolics systems of the carotid body account for the perception of not all chemical stimuli, but only of acids and some alkaloids. These data reveal the heteregeneity of the carotid chemosensory system not only in the amphibians (which was known earlier), but in mammals as well.     

Effects of cardiac glycosides on RNA content in cardio-regulating structures of the hindbrain]

In the experiments on 112 white mongrel male rats using cytophotometric investigation the authors showed that digoxin in doses 0.89 and 8.9 micrograms/g in single and repeated subcutaneous administration influences differently the level of RNA in cardio-regulating structures of the hindbrain.     

Effect of strophanthin and digoxin on the activity of an experimental epileptogenic focus in the frog hippocampus

It has been shown on frogs with epileptogenic focus induced by the injection of penicillin (1000 U in 0.4 ml) into the hippocamp that preinjection (or injection on the background of the functioning epileptogenic focus) of strophanthin (1.8 and 0.18 microgram/g) or digoxin (1.2 micrograms/g) into spinal lymphaticus sac led to a sharp increase in interparoxysmal epileptiform discharges and electrographic correlates of fits on the ECG. The influence of cardiac glycosides upon the epileptized cerebral neurons is thought to be associated with the capacity of these drugs to inhibit Na+, K+-ATPase of neurons and their axons resulting in the disturbance of cerebral mediator activity.