Activity of the climbing fiber innervating various Purkinje cells

Low-amplitude potentials (10-130 microV) related to the action of a distant branch of the climbing fiber, which elicits complex spikes of the reference Purkinje cell were revealed by means of potential averaging synchronously with complex spikes of Purkinje cells in 10 out of 255 paired records of cerebellar Purkinje cells activity and extracellular field potentials at interelectrode distances of 200-1500 microns. These potential waves had a stable form in independent sets of data. In 3 out of 10 cases, the low-amplitude potentials included a slow (about 100 ms in duration) component. In one case, both test and reference electrodes recorded both simple and complex spikes of different Purkinje cells so that complex spikes of both cells were practically synchronous (conditional probability of complex spikes p = 0.97, onset time difference 0.54 ms). Thus for the first time in cerebellar physiology both simple and complex spikes activity of two Purkinje cells controlled by the same climbing fiber was recorded.     

Interaction of isolated synaptic vesicles with synaptic contacts in the rat brain

The effects of Mg-ATP, EGTA, EDTA and dicyclohexylcarbodiimide on the changes in the intensity of light scattering were studied in rat brain synaptic vesicles (SV) suspended in saccharose-buffer medium. Specific interactions between SV and isolated synaptic junctional complex were observed in the presence of Mg-ATP and calmodulin. An in vitro model of exocytosis is discussed.     

A new method of assessing anxiety-phobic states in rats]

A new multiparameter method for evaluating anxiety-phobic states in rats is elaborated. The method is based on the ranged scale consisting of parameters which characterize the species-specific rat response to the series of ethologically adequate test-stimuli inducing manifestation of the anxiety-phobic states. The method makes it possible to evaluate individual anxiety-phobic level in rats, to form experimental groups with rats of known individual anxiety-phobic level, to conduct repeated observations in the same animals. The method is easy to perform in laboratory and makes it possible to get the results quickly.     

Phylogeny of the order Rodentia inferred from structural analysis of short retrotransposon B1

A large-scale study of short retroposon (SINE) B1 has been conducted in the genome of rodents from most of the known families of this mammalian order. The B1 nucleotide sequences of rodents from different families exhibited a number of characteristic features including substitutions, deletions, and tandem duplications. Comparing the distribution of these features among the rodent families, the currently discussed phylogenetic relationships were tested. The results of analysis indicated (1) an early divergence of Sciuridae and related families (Aplodontidae and Gliridae) from the other rodents; (2) a possible subsequent divergence of beavers (Castoridae); (3) a monophyletic origin of the group Hystricognathi, which includes several families, such as porcupines (Hystricidae) and guinea pigs (Caviidae); (4) a possible monophyletic origin of the group formed by the remaining families, including six families of mouselike rodents (Myodonta). Various approaches to the use of short retroposons for phylogenetic studies are discussed.     

Study of water exchange in skin tissues by microwave dielectrometry

The complex dielectric permitivity of human skin was measured at a frequency of 42 GHz, and a method for calculating water content in skin tissues in vivo was proposed. The water content reaction of skin to standard physical exercises and nontoxic doses of nicotine was investigated. The functionally related changes in skin dielectric properties were interpreted as structural rearrangements of water contained in blood and tissues fluids.     

The accumulation and degradation dynamics of cyanophycin in cyanobacteria grown in symbiotic associations with plant tissues and cells

Five different artificial associations of cyanobacterial cells with the cells or tissues of nightshade and rauwolfia were studied. The associations grown on nitrogen-containing media produced heterocysts. Cyanobacterial cells in the associations retained their ability to take up bound nitrogen from the medium, to store it in the form of cyanophycin granules, and to use them in the process of symbiotic growth. The synthesis and degradation of cyanophycin granules in cyanobacterial cells were more active in the associations than in monocultures. In the symbiotic associations of Chlorogloeopsis fritschii ATCC 27193 with Solanum laciniatum cells and of Nostoc muscorum CALU 304 with the Rauwolfia serpentina callus, heterocysts were produced at 3- to 30-fold higher cyanophycin contents than in cyanobacterial monocultures. In contrast, in the association of N. muscorum CALU 304 with the Solanum dulcamara callus, heterocysts were produced at lower cyanophycin contents than in the N. muscorum CALU 304 monoculture. The degradation of cyanophycin granules in N. muscorum CALU 304 cells grown in associations with plant tissues or cells was subjected to mathematical analysis. The activation of cyanophycin degradation and heterocyst production in the associations N. muscorum CALU 304-R. serpentina and C. fritschii-S. laciniatum was accompanied by an enhanced synthesis of the nitrogen-containing alkaloids in plant cells. The data obtained suggest that an integrated system of nitrogen homeostasis can be formed in symbiotic associations. Depending on the growth stage of an association, its plant member can either stimulate the accumulation of bound nitrogen in vegetative cyanobacterial cells in the form of cyanophycin granules, or activate their degradation, or initiate the formation of heterocysts independently of the cyanobacterial sensory-signalling system.     

Comparison of atrial premature depolarization topography during vagal stimulation and humoral acetylcholine administration

Epicardial atrial mapping in open-chest dogs during different cholinergic influences has shown that, in acetylcholine administration and vagal stimulation, spatial distribution of atrial premature depolarisation (APDs) seems to be similar to prevalence of ectopic sources from both atria and atrial septum. Spatial distribution of the APDs in acetylcholine administration in the sinus node artery was limited to the region of this artery so that the APDs mainly arise from intercaval area of the right atrium and from atrial septum, but never from the left atrium. The latent pacemakers spread over both atria and atrial septum, could participate in initiation of cholinergically-induced APDs and atrial fibrillation. A direct effect of acetylcholine seems to be necessary for development of arrhythmic activity of the latent pacemakers.