Physiological prerequisites for successful interaction between child and computer

The following specific psychophysiological functions, important for computer work, were identified in children aged five to six years: the functional mobility of nervous processes; the accuracy of hand kinesthesia; the functional state of the accommodative system of the eye; mental capacity, volume and concentration; and short-term memory function. A considerable number of preschoolers (47%) proved to have an insufficient level of development of body functions, necessary for successful interaction with a computer.     

Gamasid mites (Parasitiformes,Mesostigmata) in nests of passerine birds on the Arctic Seven Islands Archipelago,the Barents Sea

Examination of 31 nests of 6 common passerine bird species collected on the Seven Islands Archipelago (the Barents Sea) revealed 25 species of gamasid mites. Most of them belonged to the widespread free-living species commonly occurring in the neighboring taiga and southern tundra areas. There were practically no true Arctic forms among the gamasids found; by contrast, the local flora consisted almost by half of Arctic and Hypoarctic species. The findings of only one species, Neoseiulus cf. tobon, appear to be restricted to the Arctic, while the range of the rare parthenogenetic Iphidinychus gaieri may be restricted to Hypoarctic and mountainous regions of Eurasia. No bird parasites were recorded. Host specificity of the mite assemblages of the nests was not observed.     

The HicAB cassette, a putative novel, RNA-targeting toxin-antitoxin system in archaea and bacteria

Toxin-antitoxin systems (TAS) are abundant, diverse, horizontally mobile gene modules that encode powerful resistance mechanisms in prokaryotes. We use the comparative-genomic approach to predict a new TAS that consists of a two-gene cassette encoding uncharacterized HicA and HicB proteins. Numerous bacterial and archaeal genomes encode from one to eight HicAB modules which appear to be highly prone to horizontal gene transfer. The HicB protein (COG1598/COG4226) has a partially degraded RNAse H fold, whereas HicA (COG1724) contains a double-stranded RNA-binding domain. The stable combination of these two domains suggests a link to RNA metabolism, possibly, via an RNA interference-type mechanism. In most HicB proteins, the RNAse H-like domain is fused to a DNA-binding domain, either of the ribbon-helix-helix or of the helix-turn-helix class; in other TAS, proteins containing these DNA-binding domains function as antitoxins. Thus, the HicAB module is predicted to be a novel TAS whose mechanism involves RNA-binding and, possibly, cleavage.     

Endocytic receptor LRP together with tPA and PAI-1 coordinates Mac-1-dependent macrophage migration

Migration of activated macrophages is essential for resolution of acute inflammation and the initiation of adaptive immunity. Here, we show that efficient macrophage migration in inflammatory environment depends on Mac-1 recognition of a binary complex consisting of fibrin within the provisional matrix and the protease tPA (tissue-type plasminogen activator). Subsequent neutralization of tPA by its inhibitor PAI-1 enhances binding of the integrin-protease-inhibitor complex to the endocytic receptor LRP (lipoprotein receptor-related protein), triggering a switch from cell adhesion to cell detachment. Genetic inactivation of Mac-1, tPA, PAI-1 or LRP but not the protease uPA abrogates macrophage migration. The defective macrophage migration in PAI-1-deficient mice can be restored by wild-type but not by a mutant PAI-1 that does not interact with LRP. In vitro analysis shows that tPA promotes Mac-1-mediated adhesion, whereas PAI-1 and LRP facilitate its transition to cell retraction. Our results emphasize the importance of ordered transitions both temporally and spatially between individual steps of cell migration, and support a model where efficient migration of inflammatory macrophages depends on cooperation of three physiologically prominent systems (integrins, coagulation and fibrinolysis, and endocytosis).     

Growing seasons of Nordic mountain birch in northernmost Europe as indicated by long-term field studies and analyses of satellite images

The phenophases first greening (bud burst) and yellowing of Nordic mountain birch (Betula pubescens ssp.tortuosa, also called B. p. ssp. czerepanovii) were observed at three sites on the Kola Peninsula in northernmost Europe during the period 1964–2003, and at two sites in the trans-boundary Pasvik-Enare region during 1994–2003. The field observations were compared with satellite images based on the GIMMS-NDVI dataset covering 1982–2002 at the start and end of the growing season. A trend for a delay of first greening was observed at only one of the sites (Kandalaksha) over the 40 year period. This fits well with the delayed onset of the growing season for that site based on satellite images. No significant changes in time of greening at the other sites were found with either field observations or satellite analyses throughout the study period. These results differ from the earlier spring generally observed in other parts of Europe in recent decades. In the coldest regions of Europe, e.g. in northern high mountains and the northernmost continental areas, increased precipitation associated with the generally positive North Atlantic Oscillation in the last few decades has often fallen as snow. Increased snow may delay the time of onset of the growing season, although increased temperature generally causes earlier spring phenophases. Autumn yellowing of birch leaves tends towards an earlier date at all sites. Due to both later birch greening and earlier yellowing at the Kandalaksha site, the growing season there has also become significantly shorter during the years observed. The sites showing the most advanced yellowing in the field throughout the study period fit well with areas showing an earlier end of the growing season from satellite images covering 1982–2002. The earlier yellowing is highly correlated with a trend at the sites in autumn for earlier decreasing air temperature over the study period, indicating that this environmental factor is important also for autumn phenophases.     

Stress-hyperresponsive period in postnatal development of hypothalamic-hypophyseal-adrenal system in mice

OBJECTIVE OF THE STUDY: to compare response to stress, activity of adenylatcyclase and enzymes of steroidogenesis in adrenal cells in 3-week and adult (15-week) mice. In 3-week mice, basal and stressor level of blood corticosterone was increased. Their response to stress was faster developing as compared with adult mice. In vitro, 3-week mice had enhanced adrenal sensitivity to ACTH, corticosterone release in response to ACTH, exogenous cAMP and progesterone; and the cAMP level in the cells stimulated with ACTH and forscoline. Thus, in 3-week mice, a stress-hyperresponsive period occurs due to increased release of corticosterone and adrenal sensitivity to ACTH. The reason of this involves enhanced activity of adenylatcyclase and intracellular enzymes of steroidogenesis.     

Steroidogenesis in adrenal glands of young and adult female mice with hyperexpression of the Aguoti gene

Dominant mutation Agouti yellow (AY) leads to ectopic overexpression of the Agouti gene and yellow coat color in mice. Furthermore, the mutation Ay increased adrenal response to emotional stress. The study assessed whether pleiotropic effect of the mutation Ay on adrenals function was dependent on sex and age. 3- and 15-week old female C57B1/6J mice of two agouti-genotypes: Ay/a (ectopic Agouti-gene overexpression) and a/a (absence of Agouti-protein), were investigated. Cyclic AMP level (adenylate cyclase activity) and corticosterone production in adrenal isolated cells stimulated by ACTH and dibutyrul cAMP (db-cAMP) were measured. ACTH increased cAMP accumulation to the same extent in Ay/a- and a/a-mouse adrenal cells of both ages. The dibutyrul cAMP-induced corticosterone production was higher in Ay/a than in a/a-mouse adrenal cells of both ages. The ACTH-induced corticosterone production in 3-week- old Ay/a-m/CQ was lower and in 15-week old Ay/a-mice was higher than in a/a-mice of the respective ages. The ACTH- and db-cAMP-induced steroidogenesis was not changed in Ay/a-mice and decreased in a/a-mice with age. Thus, in females as well as in males, the mutation Agouti yellow did not affect adenylate cyclase activity, increased db-cAMP-induced corticosterone production and disturbed development of adrenal cortex.     

Evolution of DNA polymerase <Emphasis Type="Italic">ι</Emphasis> structure and function in eukaryotes

Analysis of DNA polymerase iota (Pol iota) enzymic activity in different classes of eukaryotes has shown that error-prone activity of this enzyme can be found only in mammals, and that it is completely absent from organisms that are at lower stages of development. It was supposed that the emergence of the error-prone Pol iota activity in mammals is caused by structural alteration of the active center. Possible functions of error-prone Pol iota in higher eukaryotes are discussed.