Zhurnal evoliutsionnoi biokhimii i fiziologii最新文献

Localization of biologically significant moving rhythmic sources with different pulse/pause ratio has been practically not investigated. The issue of the perception thresholds of continuously approaching sound sources is addressed in the present study. The illusion of approaching sound courses was created by noise pulse sequences linearly increasing in amplitude and emitted by a loudspeaker placed at the level of the subject's head, 1.1 m away, under free field conditions. The sequences were formed by short (5 and 10 ms) or long (70 and 100 ms) pulses. The continuous movement thresholds were evaluated by the pauses between noise pulses varying from 10 to 150 ms. For the short pulse sequences the thresholds were 49 and 41 ms, while for the long ones they decreased to 21 and 16 ms, respectively. A progressive decay of the continuous movement perception threshold in pausing between noise pulses with increasing width over the whole pulse-width range studied was observed. The thresholds for the short noise pulse sequences were 54 and 51 ms did not differ significantly, while for the long noise pulse sequences they were almost twice as long, 91 and 115 ms. For the structures representing the short (up to 10 ms) pulse sequences, the thresholds were highly variable in magnitude that is indicative of a probabilistic evaluation of movement in case of insufficient information. For the long (tens of ms) pulse sequences, the threshold evaluation was stabilized. The continuous movement thresholds and the effective masking time for sound pulse sequences coincided suggesting critical role of non-simultaneous masking for the evaluation of movement continuity.

The activities of aspartate aminotransferase (AST, E. C. 2.6.1.1) and alanine aminotransferase (ALT, E. C. 2.6.1.2) were studied in the tissues of the bivalve mollusks differing in shell color. Shell color patterns were assessed by photographing and computer processing in Adobe Photoshop CS-3. The activity of transaminases was determined by the Reitman-Frankel procedure. Four color groups of mollusks were singled out: black, intermediate, dark- and light brown. The AST and ALT activities were found to increase as shells lose color probably reflecting different tolerance of mollusks to habitats with different concentration of oxygen. The ALT distribution pattern differs appreciably in the foot of M. galloprovincialis where the highest values were found in the black-colored mussels, evidently due to the change of the predominant enzyme function. In this tissue, the reaction of transamination replenishes the pool of free amino acids required for the synthesis of byssus threads.

The most widely accepted modern scenario of prebiotic evolution that led to the emergence of the first cells on our planet is the "RNA World"--a hypothetical period of the early Earth's biosphere, when the information transfer and all the processes necessary for the functioning of the primary systems were provided by replicating RNA molecules. The essence of the "RNA World" hypothesis is based on two postulates: 1) at the initial stages of the origin of life, RNA molecules performed all functions necessary for reproduction and replication of biological molecules: informational, catalytic and structural; 2) at a certain stage of evolution arose separation of RNA and DNA, appeared genetically encoded proteins and occurred a transition to the modern world of living systems functioning. However, the analysis shows that the hypothesis of "RNA World" has a number of unsurmountable problems of chemical and informational nature. The biggest of them are: a) the unreliability of the initial components synthesis; b) a catastrophic rise of polynucleotide chains instability with their elongation; c) catastrophically low probability of formation of sequences possessing meaningful information; d) lack of a mechanism determining the regularities division of the membrane vesicles permeable to nitrogen bases and other RNA components; e) lack of driving forces for the transition from the RNA world to the much more complex world based on DNA and RNA. Therefore, the "RNA World" scenario seems unlikely.

By the low-angle light scattering technique there are revealed peculiarities of dynamics of transformation (osmotic fragility, level of hemolysis and ratio of forms by index of sphericity) of erythrocytes of hetero- (golden hamsters Mesocricetus auratus) and homoiothermal (white rats Rattus norbegicus) animals in natural hibernation and suspended animation, craniocerebral and immersion hypothermia. In control in hamsters the osmotic fragility and the level of hemolysis of erythrocytes were higher than in rats, predominant were modified forms (in particular stomatocytes). Under artificial hypothermia, regardless of the way of achievement, depth and duration, we observed changes similar in direction, but different in expression: the osmotic fragility and hemolysis increased, the portion of discocytes decreased (especially sharply in hamsters under suspended animation), the number of changed erythrocytic forms rose. In contrast, under hiberation the osmotic fragility, hemolysis and the amount of stomatocytes declined, the portion of discocytes increased, but at the same time the amount of prehemolytic forms (spherocytes) rose too. In 24 hs there occurred a decrease of osmotic fragility (after suspended animation more pronounced in hamsters) and the level of hemolysis (especially after immersion hypothermia), the portion of discocytes was restored, in hamsters after suspended animation and in rats after immersion hypothermia it even exceeded the control level; spherocytes in blood of hamsters were not revealed, in rats they were elevated. Possibly, the observed qualitative change of population of spherocytes 24 h after hypothermia toward its homogeneity is determined not only at the level of elimination of old and defected cells, activation of erythropoiesis, the appearance of highly resistant erythrocytes, but also at the level of time membrane-stabilizing mechanisms.

The activity of hydrolases (maltase, saccharase, amylolytic activity) in the intestinal mucosa of the plankton-feeding zope Ballerus ballerus and the benthos-feeding white-eye bream Ballerus sapa was investigated. The temperature characteristics of maltase hydrolysis (T(opt) and E(act)) are similar in both species. The lower K(m) of maltase hydrolysis in the white-eye bream reflects a higher enzyme/substrate affinity and indicates a more effective carbohydrate hydrolysis in the benthos-versus plankton-feeding species. The glycosidase activity in the white-eye bream is twice as high as in the zope. This may be due not only to different feeding spectra and biochemical food contents but also to the differences in thyroid status of species under consideration.

The responses of osphradium in the fresh-water mollusk Viviparus sp. and single osphradial neurons in the pond snail Lymnaea stagnalis to L-glutamine and L-asparagine as well as the changes in these responses under the effect of heavy metals (Cu, Cd) were recorded electrophysiologically. The functional connections of osphradium with the identified neurons of the central pattern generator of respiratory movements and cardiac activity as well as the modification of these connections under the effect of short-term application of HgCl2 solution on the snail's osphradium were investigated. The cardiac rhythm in the mollusk Littorina littorea under the effect of Cu ions was registered non-invasively in long-lasting experiments. The dose-dependent short-term effects of heavy metals changes after osphradium injury were revealed. The implication of osphradium in adaptive reactions of the cardiac system in aquatic mollusks to the environmental heavy metal pollution is suggested. The dependence of cardiac rhythm on the degree of accumulation of copper ions in the mollusk tissues was detected. The results obtained are essential for unraveling neural mechanisms and pathways allowing heavy metals to affect the functional state of hydrobionts, particularly, the cardiac activity frequency characteristics of which are widely used as informative biomarkers to assess physiological condition of aquatic invertebrates.

One of the approaches to creating the regulators of G-protein-coupled receptors (GPCR) is the development of peptides that structurally correspond to the functionally important regions of the intracellular extracellular loops of the receptors. GPCR-peptides can selectively regulate the functional activity of homologous receptor and affect the hormonal signal transduction via the receptor. Among the peptides corresponding to the intracellular regions of GPCR, their derivatives modified with hydrophobic radicals exhibit the highest activity and selectivity of action in vitro and in vivo. Ample evidence demonstrates that lipophilic GPCR-peptides may be used to treat diseases and various abnormalities that depend on the functional activity of receptors homologous to them. In turn, the peptides corresponding to the extracellular regions of GPCR can be used as functional probes for studying the specific interaction between the receptors and their ligands, as well as for studying the etiology and pathogenesis of autoimmune diseases caused by the production of antibodies to GPCR antigenic determinants that are localized in the receptor extracellular loops. The present review focuses on the recent achievements in development and application of GPCR-peptides and on the prospects for their further use in medicine and fundamental biology.

A comparative study of the major liposoluble antioxidant, vitamin E (α-tocopherol), content was conducted in carnivorous mammals (polar fox, silver fox, raccoon dog, mink, sable) during late autumn under natural lowering of temperature. The highest vitamin E content in liver and kidney was found in polar fox and raccoon dog, obviously due to seasonal metabolic changes and ecological specialization determining the accumulation of considerable amounts of tocopherol both in polar and hibernating species. To investigate the features of vitamin E accumulation, the tocopherol loading experiment was implemented on three species (polar fox, silver fox, mink). It was shown that polar fox, as compared to silverfox and mink, exhibits a higher ability to reserve vitamin E. The established differences in tocopherol content and distribution in different species should be considered as a genetically fixed reaction to the effect of environment underlain by metabolic differences in animals with different ecological specialization. The ability of tocopherol to accumulate in tissues and organs allows considering its essential role in stabilization of the antioxidant system and ensuring thereby a seasonal cold resistance.

Glial fibrillary acidic protein (GFAP) refers to the type III intermediate filament proteins and is the essential component of the cytoskeleton in astrocytes of all vertebrates. This review presents current data on the molecular organization of GFAP in a comparative aspect. The results of most relevant studies using immunocytochemical labeling of the protein are summarized. The data on the changes in expression of GFAP in Alexander disease caused by the primary pathology of astrocytes are presented.