N. G. Solomonov

Preliminary Study of a Mummified Woolly Rhinoceros from the Lower Reaches of the Kolyma River

Blum., 1799) (Fig. 1) wasfound on the right bank of the Lower Kolyma River, ina gold field at the upper reaches of the Malaya Filip-pova River (8 km east of the village of Cherskii of theNizhnekolymskii District of Yakutia). We studied theburial place on October 10, 2007, and the specimen inMarch, 2008, as it was brought to the MammothMuseum of the Institute of Applied Ecology of North,Yakutsk (IPES). Most of the mummified corpse waspreserved, including the left half of the trunk, with skinof the head and ear, the skull with the lower jaw, thefore and hind legs (Figs. 1–3). Small bunches of shortcoarse light brown wool are only preserved on lowersites of legs. The right side of the body and the rightlegs are lost (apparently, cut off by a bulldozer). Mostof the inner organs are lost; however, intestine is prob-ably partially preserved. The same locality has yielded anumber of specimens isolated from the trunk, i.e., the rightpelvis, the lower part of the right hind leg with soft tissues(Fig. 3b), and bones of the right foreleg (humerus, ulna,carpals, metacarpals, and two ungual phalanges). Hornshave not been found. The fragmentary genitals preservedin the specimen show that this is a female.The body measurements of this individual are ratherlarge, close to those of other adult female woolly rhi-noceroses (Table 1) [1]; the specimen weighs about900 kg; hence, during its life, the animal was about1.5 tons. The parietal length of the skull is 763 mm, thezygomatic width is 332 mm, the length of the uppertooth row is 217 mm. The mandible from the symphysisto the posterior edge of the articular process is 562 mmlong, the tooth row is 212 mm long, the ascendingramus measured from the apex of the articular processis 265 mm high. The teeth has wear signs; the majorsutures on the skull are obliterated; the nasal septum iscompletely ossified. These features, along with thebody and skull measurements, strongly suggest that therhinoceros from the vicinity of the village of Cherskiiwas an adult.The locality is situated on the left slope of east expo-sition at approximately 130 m above sea level. Thebone-bearing bed is at a depth of 5–9 m, composed offrozen dark gray loam of the Edoma Formation (glacialassemblage), with ice interbeds. Mostly loose, icy Qua-ternary deposits at the upper reaches of the Malaya Fil-ippova River form the strata about 15–17 m thick. Theburial place is at the junction of the northeastern part ofthe Kolyma Lowland and hilly spurs of the Anui Pla-teau, at about 200–630 m above sea level. According tothe soil geographical zonation, the area under study isat the boundary of the forest–tundra plain and theAlazeya–Yukagir plateau–tundra–taiga province of thetundra–forest subzone. Recent soils at the upperreaches of the Malaya Filippova River are formed oftypical cryogenic and taiga permafrost soils with vary-ing peaty and gleyey admixture. They show a high con-tent of organic matter, loamy particle-size distribution,neutral and subacid reaction, and high enzymaticpotential. Vegetation in the area studied belongs to thethin northern larch forest subzone [2]. In elevated sites,this is light larch forest, frequently with continuousmossy–lichen cover, dense undergrowth of five or sixwillow species, dwarf and Middendorf’s birches, inplaces, Manchurian alder, abundant low shrubs, andwith a small admixture of grasses and forbs. Hills arecovered with the dwarf stone pine. Lowered areas fre-quently have marshy moss–frutescent or grass–mossyopen woodlands.Paleoecological conditions in the habitat of theKolyma rhinoceros was reconstructed based on palyno-logical analysis; the ground sample comes from pri-

Involvement of some carrier proteins in thermoregulatory enhancement of respiration of mitochondria of the liver and skeletal muscles of ground squirrels (Citellus undulatus) awakening from hibernation.

† The interest of researchers to the uncoupling effect of fatty acids is largely determined by their involvement in thermogenesis in homoiothermal animals [1]. The molecular mechanisms of action of fatty acids were first determined for mitochondria of brown adipose tissue, specialized on heat production, where their effect was mediated by a specific protein, the so-called thermogenine (or the uncoupling protein UCP-1) [1, 2]. It was shown that the ADP/ATP antiporter, besides its main functions, may also implement this function in muscle and liver mitochondria: the uncoupling effect of low concentrations of fatty acids in muscle and liver mitochondria is suppressed by substrates and inhibitors of the ADP/ATP antiporter [1, 3]. Hibernating animals are characterized by the most distinct manifestation of all processes related to thermoregulation. Earlier, we studied the role of ADP/ATP antiporter in the thermoregulatory uncoupling of respiration and phosphorylation in preparations of liver and skeletal muscle mitochondria of ground squirrels awakening from hibernation. It was found that the recoupling effect of carboxyatractylate on liver and muscle mitochondria of ground squirrels dramatically increased during their awakening from hibernation [4]. At present, it is clear that a number of other proteins—anionic carriers—may mediate the uncoupling effect of free fatty acids. In particular, the involvement of the glutamate/aspartate antiporter in the realization of the uncoupling effect of fatty

Force-frequency relationship and rest potentiation in papillary muscles of Siberian ground squirrel in the period of preparation to hibernation

activity to hibernation. To date, any published data on the nature of rhythm-inotropic relationship in the myocardium of hibernating animals in this period are completely absent. Experiments were performed on the right ventricular papillary muscle isolated from ground squirrels ( C. undulatus ). The isolation, stimulation, and contraction amplitude ( A ) measurement were performed as described previously [11] at 30 ± 1°e . The steady-state force‐frequency relationships were studied in the frequency range from 0.1 to 1.0 Hz. The contraction amplitude of papillary muscles at a frequency of 0.1 Hz was taken as 100%. The maximum rest potentiation of contractility (in the range of 1 to 60 s), sometimes up to 600 s, was determined as an increment in the amplitude of the first post-rest contraction ( A 1 ) relative to the amplitude of the preceding steady-state contraction ( A 0 ) at a stimulation frequency of 0.8 Hz and calculated by the formula (( A 1 – A 0 )/ A 0 ) × 100, %) [14]. The mechanical restitution curves were obtained by plotting the increment in A 1 versus pause duration. The data are expressed as the mean and square error of the mean ( p < 0.05).

Seasonal specificity of the frequency-force dependence in the myocardium of ground squirrel, Citellus undulatus.

The heart of hibernators is capable of functioning without arrhythmia and calcium overload within the body temperature range from 0 to 37 ° C. In contrast, the body temperature decrease to 32 ° C induces atrial fibrillation in nonhibernating mammals. Further decrease in body temperature of nonhibernating mammals below 20 ° C exerts extrasystole and ventricular fibrillation [1, 2]. The mechanisms of the unique resistance of the heart of hibernators are not sufficiently understood. The rhythmoinotropic relations (dependence of the contraction force on the stimulation frequency) is an important characteristic of myocardium contractility [3]. It was found that the type of the frequency–force relationship (FFR) in the myocardium of hibernators varies in accordance with the animal’s state (hibernating or active) [4–6]. However, the mechanisms of this variability are obscure, whereas the literature on this subject is scarce and controversial. Seasonal Specificity of the Frequency–Force Dependence in the Myocardium of Ground Squirrel, Citellus undulatus L. A. Andreeva*, O. V. Nakipova*, N. A. Chumaeva*, L. S. Kosarskii*, S. G. Kolaeva*, N. I. Kukushkin*, and Corresponding Member of the RAS N. G. Solomonov**

Frequency-dependent effect of insulin on myocardial contractility in active ground squirrel Citellus undulatus in different seasons.

Insulin plays a key role in the regulation of myocardial contractility in normal and pathological states. However, the mechanisms of its inotropic effect are still unknown, and the published data are contradictory [1–4]. It is known that insulin increases the contractility of the myocardium in different animal species [1, 2]. However, in some cases, insulin and insulin-like agents either have no effect on the contractility [1, 3, 4] or suppress it [5, 6]. It was shown that the pattern of insulin effects may change in pathologies [4] and depends on the age of the animals [3, 5] and the experimental conditions [6]. Earlier, we demonstrated a pronounced multidirectional effect of insulin in the myocardium of the Yakutian ground squirrel [7, 8]. The discovered seasonal variability of the sensitivity of the myocardium to insulin and a pronounced dependence of its effects on the animal’s state (active, hibernating, or awakening) make the myocardium of hibernators a convenient model for studying the mechanisms of the insulin effects on the myocardium.