Responses of dorsal and ventral thalamic neurons to visual stimulation in Emys orbicularis tortoises]

Extracellular studies have been made on the background activity and reactions to visual stimuli in neurons of nucleus rotundus and nucleus suprapeduncularis of the thalamus in the tortoise E. orbicularis. Reactions of on-off type to diffuse light flashes were recorded predominantly in both of the nuclei, whereas specific reactions to movement stimuli were found in the neurons of n. rotundus. The receptive area of the neurons in both of the nuclei involves all the visual field of one or both of the eyes. The structure of the receptive area of the neurons of n. suprapeduncularis is relatively homogeneous, whereas the receptive area of the neurons in n. rotundus exhibits a zone with an increased excitability under the horizontal meridian. After a damage of tectum opticum, the heterogeneity of the receptive areas and the specific responses to movement in cells of n. rotundus disappeared, while thresholds of the reactions increased. In the neurons of n. suprapeduncularis homogeneous structure of the receptive area remained unaffected, the thresholds of the reactions being increased as well.     

The Mechanisms of Stimulation of Migration and Invasion of Tumor Cells by Extracellular Heat Shock Protein 90 (eHsp90) in vitro

Biophysics - Extracellular heat shock protein 90 (eHsp90) plays an important role in cell motility, invasion, and metastasis of tumor cells. eHsp90 stimulates migration and invasion of cells via...     

Effect of centimeter microwaves on the antibody production in mice

The effect of low-intensity microwaves (8.15-18 GHz, 0.3 or 1 microW/cm2, 1.5 h daily for 30 days) on antibody production in healthy male NMRI mice after immunization with affinity-purified carboanhydrase isolated from bovine erythrocytes with and without Freund's adjuvant was studied. It was found that exposure to microwaves leads to an increase in the concentration of antibodies in blood plasma, the stimulating effect being more pronounced in the primary immune response. It is assumed that the effect of enhancement of the immune response by the action of centimeter microwaves can be used in the adjuvant therapy.     

Release of the glucose-regulated protein 94 by baby hamster kidney cells

Glucose-regulated protein 94 (grp94) is a major component of the endoplasmic reticulum (ER) lumen of eukaryotic cells. We showed that grp94 is released from baby hamster kidney (BHK-21) cells into a serum-free medium. The exit of grp94 into the medium was not related to the protein discharge due to cell death and was independent of de novo protein synthesis. The treatment of cells with brefeldin A and monensin, the inhibitors of the classical pathway of protein secretion, did not decrease the extracellular level of grp94, indicating that the discharge of grp94 from cells does not occur through the ER/Golgi-dependent pathway. Exosomes, membrane vesicles secreted by several cell types, were not involved in the release of grp94 from cells. Methyl-β-cyclodextrin, a substance that disrupts the lipid raft organization, considerably reduced the extracellular level of grp94, indicating that lipid rafts are involved in the liberation of grp94 from BHK-21 cells. The results suggest that BHK-21 cells release grp94 into the serum-free medium via the nonclassical secretory pathway in which lipid rafts play an important role. Copyright ? 2012 John Wiley & Sons, Ltd.     

Development of an immunoenzyme method for detection and quantitative determination of microcystins

An indirect competitive immunoenzyme method for the quantitative estimation of microcystins (MCs) in water (MC-ELISA) using prepared MC-specific polyclonal antibodies was developed. The threshold concentration of the most widespread and highly toxic MC-LR, which was reliably detected using MC-ELISA, was 0.05 ± 0.01 ng/mL; the 50% inhibition concentration was 0.41 ± 0.05 ng/mL; and the concentration range for the quantitative estimation of MC-LR was 0.1–5.0 ng/mL. The MC-ELISA made it possible to detect MC-LR in water at concentrations 10–20 times lower than the World Health Organization guideline level for drinking water and 100–200 times lower than the allowable MC concentrations in water bodies. A group of cross-reacting MCs and nodularin was detected using MC-ELISA. This method can be applied for monitoring MC concentrations in water bodies and drinking water.     

Cell surface heparan sulfate proteoglycans are involved in the binding of Hsp90α and Hsp90β to the cell plasma membrane

Extracellular membrane-bound and secreted heat shock protein 90 (Hsp90) is known to be involved in cell motility and invasion. The mechanism of Hsp90 anchoring to the plasma membrane remains obscure. We showed that treatment of human glioblastoma A-172 and fibrosarcoma HT1080 cells with sodium chlorate, heparinase, and heparin causes a prominent loss of 2 Hsp90 cytosolic isoforms, Hsp90α and Hsp90β, from the cell surface and strongly inhibits the binding of exogenous Hsp90 to cells. We revealed that Hsp90α and Hsp90β are partly colocalized with heparan sulfate proteoglycans (HSPGs) on the cell surface and that this colocalization was sensitive to heparin. The results demonstrate that cell surface HSPGs are involved in the binding/anchoring of Hsp90α and Hsp90β to the plasma membrane.     

Level of neuroactive steroids in the brain and sex-related peculiarities of formation and extinction of conditioned reflex in rats

Sex-related peculiarities of dynamics of brain sex steroids in the process of learning and extinction of the conditioned reflex of passive avoidance have been studied in model experiment. Prior to learning of the conditioned reflex, female rats were found to be distinguished by manifestation of anxiety and fear as compared with male rats. At formation of the conditioned reflex, no significant sex-related differences were detected between males and females, whereas extinction of the conditioned reaction of passive avoidance in males occurred by 2–3 days faster than in females. At learning of conditioned reaction of passive avoidance, in sexually mature male rats there was revealed an increase of the testosterone content in various brain structures, especially in hippocampus and frontal cortex, while its level in blood plasma remained unchanged. Also shown was an elevation of estradiol concentration in female amygdale, whereas at extinction of the conditioned reaction of passive avoidance, a rise of estradiol values was noted in hippocampus and cingular cortex. At the same time, the testosterone level in blood plasma did not change, whereas after extinction of the conditioned reflex the estradiol concentration decreased statistically significantly. Different dynamics of changes of the sex steroid levels in brain and blood plasma can indicate a possibility of their formation in the nervous tissue. The performed correlation analysis confirms the concept of selective involvement of testosterone and estradiol of individual brain structures in realization of processes of learning and memory in sexually mature male and female rats.     

The effect of light stimulation in the pre- and postnatal periods on the synaptic ultrastructure in the chick hyperstriatum

Morphometric analysis of synapses in the medial parts of the ventral and accessorium hyperstriatum in the right and left hemispheres in chicks has been performed after rhythmic optic stimulation from the 18th day of incubation, flickering stimulation at the 11-12th hour after hatching, as well as in chicks reared under normal illumination and those kept in darkness within the first two days after hatching. Numeric density of synapses, mean dimensions of postsynaptic thickenings, the number of synaptic vesicles per active zone in presynapses and mean length of the whole axodendritic contact were determined in ultrathin sections. The data obtained indicate that early visual experience significantly affects the synaptic structures in both parts of the brain. A discussion is made of the plasticity of synapses during stimulation, morphological and functional relationships between hyperstriatal areas in relation to different aspects of processing and storage of visual information.