N.G. Solomonov

MYOGLOBIN CONTENT IN SKELETAL MUSCLES OF HIBERNATING GROUND SQUIRRELS RISES IN AUTUMN AND WINTER

The content of myoglobin (Mb) in skeletal muscles of Arctic Yakutian ground squirrel (Citellus undulatus Pallas) was measured in the active euthermic summer and prehibernating autumn animals as well as in hibernating and awake animals in winter. The myoglobin content in winter, irrespective of the state of the animal, was found to be about three times higher than in summer. The content of myoglobin in autumn was also two-fold increased compared to summer, suggesting that high myoglobin level is necessary for hibernation. Analysis of biochemical data available suggests that the increase in myoglobin content in winter is probably related to a high oxygen demand of muscles at the first stage of arousal (non-shivering thermogenesis) when rectal temperature rises from 0 to 10-12 degrees C. At this stage, the oxygen-dependent processes in muscles proceed under the conditions when peripheral blood flow is blocked and anaerobic glycolysis is switched off.

Study of Pollen and Spores from the Stomach of a Fossil Woolly Rhinoceros Found in the Lower Reaches of the Kolyma River

E). A study of the stomach contentsof the fossilized rhinoceros using palynological methods with the aim of establishing the particularities of itsdiet and recreating the paleofloristic conditions of theperiod of its existence was of great interest.A sample of the remnants of the stomach lump ofthe woolly rhinoceros was characterized by a high concentration of pollen and spores (more than1700 micrograins in one preparation). Most pollengrains were very well preserved.In the general spectrum, the pollen of grass plantspredominates (98.5%). Pollen from trees and bushesaccounts of 0.9%, and 0.6% are represented by spores(Table 1). The grass pollen composition is mainlyaccounted for by the pollen of Gramineae (45.9%)and Compositae (40.6%), in which wormwood pollendominates (40.1%). Up to 10 varieties of pollen can bedistinguished in the Gramineae pollen by morphological characteristics. They differ in size, grain shape,pore, and exine structure, etc. It is very difficult toclassify the Gramineae pollen down to the specieslevel, and this has not been done yet. Nonetheless,judging by the morphological particularities of thepollen, it can be assumed that it belongs to differentGramineae species. Wormwood pollen is also represented by various species; on the basis of its morphology, we assume that it is composed of

Characteristics of seasonal dynamics of Betula platyphylla Sukacz. Dehydrins associated with frost hardiness development under the cryolitic zone conditions.

258 The frost hardiness degree of perennial plants is determined by seasonal cold acclimation and deaccli mation depending on the rhythms of photoperiod and temperature in the habitats. The sharp continental climate of Central Yakutia determines the specific ity of plants’ passing through the hardening phase, earlier deep dormancy under the conditions of its relative shortness, and a very long ecodormant stage. The last one occurs at extremely low temper atures (down to –60°C). The plant frost hardiness is based on the ability of cells to cope with dehydration during dormancy. Dehydrins are one of the protec tive protein groups involved in these processes [1–3]. They form group II of late embryogenesis abundant (LEA) proteins. Dehydrins are also found under stress conditions (low temperatures, drought, or a high salinity) accompanied by desiccation. They are characterized by highly conserved Y, S, and K seg ments, areas rich in glycine and a high hydrophilicity. Dehydrins contribute to stabilization of macromole cules and membranes.

The ecology of the habitats, nesting, and migration of the eastern population of the siberian crane (Grus leucogeranus Pallas, 1773)

The structure of the distribution range and population of the Siberian crane in its regular breeding area in the northeastern Yakutian tundra are described, as well as the migration terms, intensity, routes, and stopover sites. The territorial pairs (71.7–97.1% of the summer population), which in 2006 were represented by the birds at ages of 8 to 21 years (mainly 20 years, accounting for 45.4%), constantly stayed on an area of 7.3–16.5 km2 independently of their participation in breeding. The breeding success in this population varies from 4.3–8.7 to 65.0–83.3% and depends on the climatic conditions at the beginning of egg laying; these climatic conditions change rather unpredictably from year to year, as well as being seasonally unstable. This explains that fact that some generations in this population are particularly vulnerable to natural elimination factors because of their low numbers. Bird migration in Yakutia follows a narrow tunnel with the highest migratory intensity in the Middle Aldan Valley. In the fall, 30 to 50% of the entire population is visually recorded there.

Endogenous ethanol and acetaldehyde in the mechanisms regulating vital activities during hibernation

347 The adaptations based on a decrease in the envi ronment–body temperature gradient at the expense of a considerable decrease in the level of metabolism in the body (hibernation) hold a special place among the animal adaptations to cold [1, 2]. The body of hiber nating animals possesses a regulatory system that ensures homeostasis at a minimal yet stable metabolic level. During hibernation, the body temperature of hibernating animals falls to 0°C, and the basal meta bolic rate decreases 30 to 250 fold. During the hiber nation period, animals repeatedly wake up, elevating their body temperature for short periods (1.5–2 h) from 0–4 to 30–36°C for several hours with subse quent return to the hibernation state [3]. Over 90% of all winter energy expenditure of the body is spent dur ing spontaneous awakenings. Hibernation “triggers,” PHYSIOLOGY

Bighorn sheep from Yakutia

244 The living bighorn sheep Ovis (Pachyceros) nivicola Eschscholtz, 1829 is an exclusively mountain animal. Its geographical range includes some mountain ridges of northeastern and southern Yakutia and adjacent regions (Stanovoi Mountain Range, Dzhugdzhur), the Chukchi Peninsula (Anyui and Chukchi plateaus), Koryak Plateau, and Kamchatka Peninsula. An iso lated population of this species inhabits the Putorana Plateau [1–4]. It was repeatedly indicated that, previ ously, O. nivicola had a larger range. Fossil specimens of the bighorn sheep dated Late Pleistocene come from a number of localities outside the modern species range, i.e., southern Western Siberia [5, 6], upper reaches of the Yenisei River [7], Transbaikalia and Baikal Region [2, 5, 7, 8], Yakutia [2, 9], and Sakhalin [10]. In central Yakutia, the fossil bighorn sheep has been found on the Vilyui River in the vicinity of the town of Verkhnevilyuisk (Vilyui River), Yakutsk (Lena River), and the village of Kachikattsy (Buotama River) [2, 9].

Annual dynamics of the body temperature in musk oxen (Ovibos moschatus) under the conditions of Yakutia

Republic of Sakha (Yakutia), situated in northeast ern Siberia, is one of the coldest regions of Russia [2]. The adaptive potential of species living here is expressed, in particular, in their ecology and energy metabolism. The body temperature is an integrated indicator of the thermal condition of animals and humans. In the body, we distinguish the homeother mal core and the heterothermal envelope. Under favorable conditions, the reactions in the envelope maintain an optimal temperature in the core of the body [4]. By changes in the temperature of the body envelope, we may estimate the influence of the ambi ent temperature on the body and the ability of the body to resist this effect [8, 9].

Role of the Ca2+ cycle in uncoupling of oxidative phosphorylation in liver mitochondria of cold-acclimated rats

Cold acclimation of Wistar rats for 2-4 weeks at about 3 degrees C resulted in an increased respiration rate and a reduced ADP/O ratio in liver mitochondria. With increasing duration of acclimation up to 10-12 weeks, these parameters returned to a normal level. The increase in the respiration rate and the decline of the mitochondrial ADP/O ratio were associated with a significant activation of the electroneutral release of Ca2+. When the animals were acclimated for 10-12 weeks the rate of Ca2+ release reduced to control values. The addition of 1 microM ruthenium red resulted in a decrease in the rates of mitochondrial respiration in control and cold-acclimated rats to approximately equal values and in a partial restoration of the ADP/O ratio in liver mitochondria of rats kept in the cold for 2-4 weeks. The respiratory activity of mitochondria isolated in the presence of 1 mM EGTA unaffected by ruthenium red.