Electrical feedback in the chemical synapses

Electrical feedback in chemical synapses and the efficacy of synaptic transmission grow with the increase in the gap resistance, so they should be higher in invaginated synapses than in the flat ones. So the plastic changes in the invagination depth may provide a morphological basis for long-term changes in synaptic efficacy: long-term potentiation (LTP) in brain and retinal synapses. In retinal photoreceptor triad synapses, the electrical feedback can provide an "operational" (instantaneous) control of synaptic transmission.     

Subcellular reorganization of cardiomyocytes during and after temporary experimental hypothermic circulatory arrest

Ultrastructure of cardiomyocytes of the left ventricle has been studied in dogs during the experiments, performed with a general external cooling, prolonged circulatory arrest, as well as during long term periods after the operation. In the experiment without cooling it is not possible to restore hemodynamics after 30 min of total ischemia. In cardiomyocytes severe, sometimes irreversible lytic lesions are registered. Opposite to this, by the end of one hour's cardiac arrest under total cooling up to 24-22 degrees C, changes in ultrastructure of cardiomyocytes are minimal. This is proved by a stabilizing action of hypothermia to membranous, fibrillar and even labile granular cellular components. More manifested changes occur in cells after restoration of the cardiac activity and worming, though even at this stage certain morphological signs of partial restoration of synthetic processes are noted. By the third day after the operation ultrastructure of cardiomyocytes is fully normalized at an essential hypertrophy and hyperplasia of protein synthesis organels and lysosomes. Thus, under conditions of aperfusional hypothermia (24-22 degrees C) and cardiac arrest, produced with pharmacological cooling, cardiomyocytes safely survive one hour's total ischemia, presenting their ability to intracellular regeneration in full.     

Microfluorometric study of pH in frog nerves at rest and during rhythmic stimulation]

With the use of microspectrofluorimetry the pH-dynamics in the frog nerve at rest and during rhythmic excitation was investigated. Rhythmic excitation results in an increase of hydrogen ion concentration in the nerve fibres. Metabolic and ion channel inhibitors affect intracellular pH changes. The results obtained suggest different role of various transport systems (sodium pump and ion channels) in the regulation of pH at rest and during rhythmic excitation.     

Raman spectroscopy of the "potential sensor" of potential-dependent channels.

Raman spectroscopy (RS) study shows that the "potential sensor" responds to changes in intramembrane potential by conformational changes. The mechanism of regulation of the channel "gate" by the carotenoid potential sensor is discussed.     

Perception of color and volumetric shape of objects]

The problem of recognition of coloration of volume objects, illuminated simultaneously with bright point ans weak diffuse sources (having arbirary and previously unknown spectra) is considered. A mathematical model, in which a process of recognition of coloration is accompanied by determining orientations of surface elements relatively the point source is described. The information on orientation allows in many cases to calculate the volume shape of objects of the external world form their monocular "retinal" image.     

Effect of Ferulic Acid on the Colony Growth and Cell Reproduction of the Endophytic Bacterial Strain Bacillus subtilis 26D

Applied Biochemistry and Microbiology - Under stressful conditions, including infection with phytopathogens, plants produce various compounds that are growth activators, e.g., hydroxycinnamic acids...     

New data on age and conditions of buried organic-rich sediments formation in the сentral Ob River

This article presents the results of a comprehensive geochronological study of gyttja deposits from a section of a terrace above a floodplain located on the right bank of the Ob River near the town of Kolpashevo. According to the ²³⁰Th/U dating, the age of the gyttja could be dated in the range of 110–95 kyr. The results of spore–pollen analysis suggest that the gyttja deposit was formed in the period of a wide distribution of middle taiga forest landscapes with the dominance of spruce; the climatic conditions were similar to modern ones. These events probably took place in the interstadial time during MIS-5c or at the end of Kazantsevo interglacial period.     

Influence of weakened constant magnetic field on nerve cell excitability

Attenuation of the constant magnetic field by a factor of 200–250 (to ～0.2 μT) raised the excitation threshold and decreased the amplitude of the action potentials in the isolated frog sciatic nerve, and altered the conformation of carotenoids in the plasma membrane (sciatic axolemma) as well as in intracellular vesicles (cytosomes of snail ganglia). The variation in nerve excitability was supposedly caused by changes in the ordering of membrane lipids.