Sound improves distinction of low intensities of light in the visual cortex of a rabbit

Electrodes were implanted into cranium above the primary visual cortex of four rabbits (Orictolagus cuniculus). At the first stage, visual evoked potentials (VEPs) were recorded in response to substitution of threshold visual stimuli (0.28 and 0.31 cd/m2). Then the sound (2000 Hz, 84 dB, duration 40 ms) was added simultaneously to every visual stimulus. Single sounds (without visual stimuli) did not produce a VEP-response. It was found that the amplitude ofVEP component N1 (85-110 ms) in response to complex stimuli (visual and sound) increased 1.6 times as compared to "simple" visual stimulation. At the second stage, paired substitutions of 8 different visual stimuli (range 0.38-20.2 cd/m2) by each other were performed. Sensory spaces of intensity were reconstructed on the basis of factor analysis. Sensory spaces of complexes were reconstructed in a similar way for simultaneous visual and sound stimulation. Comparison of vectors representing the stimuli in the spaces showed that the addition of a sound led to a 1.4-fold expansion of the space occupied by smaller intensities (0.28; 1.02; 3.05; 6.35 cd/m2). Also, the addition of the sound led to an arrangement of intensities in an ascending order. At the same time, the sound 1.33-times narrowed the space of larger intensities (8.48; 13.7; 16.8; 20.2 cd/m2). It is suggested that the addition of a sound improves a distinction of smaller intensities and impairs a dis- tinction of larger intensities. Sensory spaces revealed by complex stimuli were two-dimensional. This fact can be a consequence of integration of sound and light in a unified complex at simultaneous stimulation.     

Effects of blockade of dopaminergic D1/D2 receptors on behavior of impulsive and self-controlled rats

Selective antagonists of D1 and D2 receptors (SCH 23 390 and raclopride respectively) were injected to rats divided on the basis of preliminary experiments into groups of"self-controlled" (preference of valuable but delayed reinforcement) and "impulsive" (choice of less valuable but immediate reinforcement) animals. Number of omissions of reactions and their latencies were recorded. In "self-controlled" rats, both drugs increased the number of reactions for less valuable immediate reinforcement, i.e., increased impulsiveness, whereas practically did not change the behavior of "impulsive" animals. Introduction of SCH 23 390 to animals ofboth groups increased the number of reaction omissions the effect being stronger in "self-controlled" animals. Raclopride also increased the number of reaction omissions in "self-controlled" rats but only on the next day after the injection. In "impulsive" animals, both drugs increased the latencies of reactions.     

Event-related potentials to visually presented verbal stimuli in the examination stress condition

The work is aimed at the study of ERPs to visually presented verbal stimuli in the examination stress condition. EEG was recorded while participants made a decision whether or not visually presented words were related to a given category. Three types of stimuli were presented: familiar words related and unrelated to the given category, and unfamiliar words. Components N170, P170 and N400 of the ERP to familiar words unrelated to the given category and unfamiliar words were higher in the stress condition than in a usual experimental situation. Component P600 was higher in the stress condition for all types of stimuli. It was suggested that enhanced N170/P170 and N400 components reflect changes in the cognitive functions ofword processing, whereas the increase in P600 is related to nonspecific arousal in the stress condition.     

Dependence of protective effect of alpha-tocopherol on its concentration and time of action on PC12 cell under conditions of oxidative stress

At the short-term incubation (0.5 and 1.5 h) of cells of the PC12 neuronal line with alpha-tocopherol, its protective effect against the cytotoxic hydrogen peroxide action was increased with rise of its concentration in samples; the protection was practically absent at action of nanomolar antioxidant concentrations, but was well expressed at its micromolar concentrations. These data agree with the concept that alpha-tocopherol increases the cell living activity by reacting directly with free radicals, which leads to formation of the less reactive compounds deprived of non-paired electron. The evidence is obtained that at the long-term action on PC12 cells, alpha-tocopherol not only in micro-, but also in nanomolar concentrations increases statistically significantly the cell living activity under conditions of oxidative stress. As follows from the obtained data, an important role in realization of the alpha-tocopherol protective effect at the long-term incubation with it seems to be played by modulation by this antioxidant of activity of protein kinase activated by extracellular signaling, phosphatidylinosite 3-kinase, and protein kinase C.     

Bounds of change in unsaturation index of fatty acid composition of phospholipids at adaptation of molluscs to biogenic and abiogenic factors of external medium

Comparative study of fatty acid composition of total phospholipids, as well as of phosphatidylcholine and phosphatidylethanolamine from hepatopancreas and leg muscle was performed on several representatives of gasteropods (Gastropoda) molluscs and bivalve (Bivalvia) mussel (Mytilus edulus). The objects of our study were marine litorins (Littorina saxsatilis) adapted to different temperature conditions of White Sea and Barents Sea, freshwater lymnaea (Lymnaea stagnalis) infested by Trematoda and mussels from White Sea and Black Sea. It was shown that depending on the existence conditions of studied tissue or lipid, the maximal change is observed in the percentage of saturated acids (4-83 %), the percentage of unsaturated acids was less expressed (1-14 %) and the changes in unsaturation index (UI) did not exceed 20 % on average. It was supposed that observed quantitative bounds of UI change under the action of different external factors is utmost for maintenance of membrane fluidity necessary for normal vital activity of cell, particularly in studied ectothermic molluscs.     

Structure and localization of sensilla on antennas of caddisflies (insecta: trichoptera)

The structures of antennal segments and ultrastructures of antennal sensilla were studied in representatives of 28 families of caddisflies from both extant suborders by the methods of light and scanning electron microscopy. Sixteen types of the sensilla have been found to occur on the antenna in Trichoptera; some of them were found for the first time. Morphological characters of the cuticular structures on the antennal surface demonstrate the significant structural differences both in various families and in the lower taxonomy levels. Specialized sensory fields differing structurally from the rest of the flagellomer surface have been found on the antennas in the suborder Phryganeina. A modified classification of sensilla based on the cuticular structures is proposed.     

Improved procedure of the search for poly(ADP-ribose) polymerase-1 potential inhibitors with use of molecular docking approach

A search for poly(ADP-ribose) polymerase-1 inhibitors by virtual screening of a chemical compound database and a subsequent experimental verification of their activities have been done. It was shown that the most efficient method to predict inhibitory properties implies a combinatorial approach joining molecular docking capabilities with structural filtration. Among more than 300000 database chemicals 9 PARP1 inhibitors were revealed; the most active ones, namely: STK031481, STK056130, and STK265022,--displayed biological effect at a micro-molar concentration (IC50 = 2.0 microM, 1.0 microM and 2.6 microM, respectively).