Meadow Birds under Waning Traditional Pasture Animal Husbandry

Biology Bulletin - As a result of long-term studies in the areas of abandoned meadows and grasslands in Arkhangelsk, Novgorod, Ivanovo, and Moscow regions, we found the main peculiarities of bird...     

Modified Canonical Profile Transport Model for Description of On-Axis Electron-Cyclotron Heating of Tokamak Plasma

Plasma Physics Reports - The specific power deposited in plasma under on-axis electron-cyclotron resonance heating (ECRH) is characterized by strong peaking, resulting in large-amplitude sawtooth...     

Alternate domains of neuron DNA topoisomerase I in developing rat brain

The DNA topoisomerase found in rat brain neurons relaxes supercoiled DNA in the absence of ATP or Mg2+. The estimated content of the active enzyme per nucleus of nerve cell is constant during development from a fetal proliferating neuroblast at the embryonic stage of 18 days to the terminally differentiated neuron (postnatal age of 60 days). The salt stability of DNA topoisomerase association with chromatin varies with the stage of development of nerve cells: at 300 mM NaCl most of the enzyme activity (greater than 90% of the removed activity) elutes from differentiated neuron chromatin, whereas only approx. 25% of the enzyme activity elutes from neuroblast chromatin.     

Ecology of sea ice biota

Summary The sea ice does not only determine the ecology of ice biota, but it also influences the pelagic systems under the ice cover and at ice edges. In this paper, new estimates of Arctic and Antarctic production of biogenic carbon are derived, and differences as well as similarities between the two oceans are examined. In ice-covered seas, high algal concentrations (blooms) occur in association with several types of conditions. Blooms often lead to high sedimentation of intact cells and faecal pellets. In addition to ice-related blooms, there is progressive accumulation of organic matter in Arctic multi-year ice, whose fate may potentially be similar to that of blooms. A fraction of the carbon fixed by microalgae that grow in sea ice or in relation to it is exported out of the production zone. This includes particulate material sinking out of the euphotic zone, and also material passed on to the food web. Pathways through which ice algal production does reach various components of the pelagic and benthic food webs, and through them such top predators as marine mammals and birds, are discussed. Concerning global climate change and biogeochemical fluxes of carbon, not all export pathways from the euphotic zone result in the sequestration of carbon for periods of hundreds of years or more. This is because various processes, that take place in both the ice and the water column, contribute to mineralize organic carbon into CO₂ before it becomes sequestered. Processes that favour the production and accumulation of biogenic carbon as well as its export to deep waters and sequestration are discussed, together with those that influence mineralization in the upper ice-covered ocean.Authors are members of SCOR Working Group 86: Ecology of Sea Ice Biota     

Characteristics of under-ice swarming of polar cod Boreogadus saida (Gadidae) in the Central Arctic Ocean

Phenological observations on under-ice swarming behavior of Polar cod Boreogadus saida were performed during the winter period 2009–2010 in the Canadian sector of the Arctic Ocean on the North Pole NP-37 drifting station. These observations and ichthyologic collections were the basis of the present study. The schools were mostly formed by the immature specimens (TL = 75–169 mm; 1+ to 4+ age), the dominating group was presented by fish of 2+ age (86–94% of total abundance). The driving factors of such large under-ice swarming of Polar cod B. saida in the Arctic are discussed, particularly, the interactions of Polar cod development and the ice drift in the studied region. This species inhabits the overcooled water (?1.8°C) under the ice, so the scheme of the antifreeze agent producing in the fish blood is considered. We make assumptions about under ice migrations of Polar cod swarming.     

Comparative analysis of gas exchange and cardiorespiratory system responses of swimmers and skiers to increasing normobaric hypoxia and physical load

Qualification-comparable groups of young men engaged in cyclic kinds of sports were tested using a stepwise increasing load on a bicycle ergometer and 25-min exponentially increasing normobaric hypoxia to a final oxygen concentration of 10%. Skiers, who had the greatest values of maximal oxygen consumption during muscular work, showed relaxed cardiorespiratory reactions and a greater decrease in hemoglobin saturation with oxygen in hypoxia. Swimmers, whose ventilatory function in the course of trainings was restricted, developed preadaptation to hypoxia, with changes in external respiration and gas exchange functions, which allowed better saturation of blood with oxygen in lungs during hypoxia. The joint assessment of the aerobic capacity during physical work and physiological responses to hypoxia showed a direct correlation between the individual maximal oxygen consumption and the rate of decrease in the blood hemoglobin saturation in increasing hypoxia, which may be promising for assessing the functional state of athletes and its correction during training.     

Waders of Agricultural Areas of Ivanovo Oblast in the Crisis of Agricultural Production

Biology Bulletin - Abstract—The agricultural landscape of Ivanovo oblast is now a sophisticated mosaic of a variety of types of lands in use and of abandoned lands at different stages of...     

Central hemodynamics and arterial stiffness in adult humans depend on the conditions of early development in the Northern Kola Peninsula

The month and place of birth, i.e., early-life conditions, at low and middle latitudes have proved to be associated with a wide range of later-life health outcomes, including cardiovascular diseases. A comparative observational study was carried out in 122 miners of both sexes residing on the northern Kola Peninsula to examine whether the early-life conditions have any effect on arterial stiffness in adult humans living in the North. The indices of aortic hemodynamics and arterial elasticity were measured using pulse wave analysis and applanation tonometry. The comparison showed that women born in the North have more compliant arteries than their counterparts born in the southern and temperate regions. The men born in summer and autumn have more distensible arteries compared to those born in winter and spring. It is supposed that these differences are due to early epigenetic modification of the genes responsible for the fibrous structure of connective tissue of the arterial wall.