| mosquito-borne arboviruses in arctic america. | mosquito-borne arboviruses are prevalent throughout subarctic regions of canada and alaska, principally in the boreal forest extending between latitudes 53 and 66 degrees n, but they have been identified in tundra regions as far north as 70 degrees n. all mosquito-borne agents have been bunyaviruses, comprising principally the snowshoe hare subtype of california encephalitis (ce) virus, but also northway virus. mosquito vectors comprise several aedes species and culiseta inornata, all of which h ... | 1975 | 1602 |
| california encephalitis virus prevalence throughout the yukon territory, 1971-1974. | california encephalitis (ce) virus (snowshoe hare subtype) was isolated from 1 of 38 pools comprising 970 unengorged female aedes canadensis mosquitoes and from 3 of 152 pools containing 5,676 a. communis mosquitoes which were collected in the yukon territory, canada between latitudes 61 and 66 degrees n during june and july 1974. during four summers 1971 through 1974, this virus was recovered from 26 of 648 pools derived from 30,686 mosquitoes of 4 species. isolation of ce virus from 1 of 109 p ... | 1975 | 239604 |
| [the characteristics of the structural-functional state of the erythrocytes from homoiothermic and heterothermic animals during hypothermic storage]. | haemoglobin leakage and permeability for 86rb and k ions during storage at normal and hypothermic conditions have been investigated in the erythrocytes of the ground squirrel citellus undulatus in hibernating, arousing and awake animals, as well as in rats. during hibernation, stabilization of the barrier properties and a decrease in passive ionic permeability of erythrocyte membrane were observed. preservation of ionic homeostasis of the erythrocytes in hibernating animals is favoured by activa ... | 1991 | 1799099 |
| [the excitability of neurons of the medial septal area in brain slices from hibernating and active citellus undulatus susliks]. | spontaneous and evoked neuronal activity of the medical septum-diagonal band complex (ms-db) has been investigated in slices from the brain of hibernating and active ground squirrels, as well as guinea pigs. in all experimental groups, the majority of the ms-db neurones exhibited high regular of rhythmic burst spontaneous activity which persisted even after synaptic blockade in half of the neuronal population. under the same conditions, the activity of the surrounding structures was completely s ... | 1991 | 1808971 |
| [the cardiotropic, hypometabolic and hypothermic activity of peptide fractions from the tissues of hibernating cold-adapted animals]. | from tissues of hibernating and active long-tailed ground squirrels and from the brain of cold-adapted yakut horses, low molecular peptide fractions were obtained which, after injection to albino mice, decreased oxygen consumption and rectal temperature in them. the same fractions exhibited negative chrono- and inotropic effects on isolated hearts of ectothermic and endothermic animals. fractions from the brain of ground squirrels and the brain of horse exhibited similar pattern of the activity. ... | 1990 | 2091416 |
| functional stability of the brain slices of ground squirrels, citellus undulatus, kept in conditions of prolonged deep periodic hypothermia: electrophysiological criteria. | the brain of hibernating animals, controlling the physiological functions during the hibernation cycles, is itself subject to deep cooling during bouts of hibernation. this suggests its high tolerance to deep hypothermia. effects of prolonged deep cooling were investigated in hippocampal and septal slices, taken from the brains of three groups of animals: hibernating ground squirrels, actively waking ground squirrels, and guinea-pigs. the slices were kept at a low temperature (2-4 degrees c) for ... | 1990 | 2270134 |
| paradoxical state-dependent excitability of the medial septal neurons in brain slices of ground squirrel, citellus undulatus. | spontaneous and evoked neuronal activity of the medial septum-diagonal band complex was investigated extracellularly in slices, taken from the brain of the three groups of animals: hibernating ground squirrels, waking ground squirrels, and guinea-pigs. all slices were incubated at 31-32 degrees c. the slices of the ground squirrels' brain were retested after keeping them for 15-36 h in the refrigerator at 2-4 degrees c. in all experimental groups the majority of the medial septum-diagonal band c ... | 1990 | 2270135 |
| california encephalitis virus endemicity in the yukon territory, 1972. | sera from 218 of 1574 (14%) small mammals collected in the yukon territory between 14 may and 13 august 1972 neutralized a yukon strain of california encephalitis virus (snowshoe-hare subtype). these included 133 of 319 (42%) snowshoe hares (lepus americanus), 84 of 1243 (7%) ground squirrels (citellus undulatus) and 1 of 12 (8%) tree squirrels (tamiasciurus hudsonicus). california encephalitis virus (snow-shoe hare subtype) was isolated from four pools of unengorged aedes communis mosquitoes co ... | 1973 | 4146347 |
| [study of squirrel myoglobin. oxidation-reduction reaction between squirrel oxymyoglobin and ferricytochrome c]. | metmyoglobin (met-mb) of yakutian ground squirrel (citellus undulatus) was isolated from skeletal muscles and fractionated using gel and ion-exchange chromatography. an electrophoretically homogeneous major fraction of met-mb (pi 7.05) was obtained with a 90% yield. the rates of the redox reaction between ground squirrel oxy-mb and horse and ground squirrel ferri-cyt c were studied in the ph range of 5-8 at ionic strengths ranging from 0.01 to 1. the experimental results were compared to the ear ... | 1995 | 7578567 |
| [biologically active peptides isolated from the brain of hibernating ground squirrels]. | more than 20 peptides have been isolated and sequenced from the brain of hibernating ground squirrel citellus undulatus. some of the isolated peptides were chemically synthesized and investigated for the spectrum of biological activity. one of the isolated peptides, neokyotorphin (thr-ser-lys-tyr-arg), earlier known as a weak analgetic, is found to have a cardiotropic and thermoregulatory activity. neokyotorphin activates in vitro voltage-dependent calcium and blocks atp-dependent potassium curr ... | 1994 | 7826417 |
| [erythrocyte membrane permeability of citellus undulatus during hibernation]. | we have studied the influence of the erythrocyte hypothermic storage of long-tailed ground squirrels at various physiological states and white mongrel rats on the impairment of the barrier function of their membranes for ferricyanide. the membranes of sleeping and awakening ground squirrels demonstrate the highest stability (the structural integrity is sustained for 3-3,5 months), meanwhile rat blood erythrocytes maintain the barrier function only for 2 weeks. beside structural and viscous chang ... | 1993 | 8395896 |
| anti-lymphoproliferative activity of brown adipose tissue of hibernating ground squirrels is mainly caused by amp. | a fraction with mol wt < 1 kda was obtained from the brown fat of hibernating ground squirrels (citellus undulatus) by means of delipidization, acid extraction, ultracentrifugation and ultrafiltration. this fraction suppressed the proliferation of mouse lymph node cells under standard mitogenic stimuli for t lymphocytes. in contrast, the fraction with mol wt < 1 kda obtained from the brown fat of active ground squirrels in spring did not display such activity. further hplc purification of the bi ... | 1995 | 8564792 |
| [seasonal changes in the structural-functional properties of erythrocyte membranes from citellus undulatus]. | the influence of hypothermic storage upon citellus undulatus erythrocytes extracted during different functional state of the hibernator: hibernation, artificial awakening in winter and summer activity has been investigated. it has been revealed that the cells of the animals, which were in the state of deep hibernation, showed in vitro higher resistance of the systems providing ionic homeostasis (na+/k+- and ca(2+)-pompes and passive permeability) not only in comparison with the cells of non-hibe ... | 1995 | 8830437 |
| [seasonal changes in brain synaptosomal membrane lipids in the ground squirrel citellus undulatus]. | | 1997 | 9102106 |
| effects of a number of short peptides isolated from the brain of the hibernating ground squirrel on the eeg and behavior in rats. | intracerebroventricular administration of the peptides kyotorphin (tyr-arg), neokyotorphin (thr-ser-lys-tyr-arg), and asp-tyr at doses of 4 and 8 micrograms altered the behavior of rats in a manner similar to that seen after similar administration of brain fractions from hibernating ground squirrels (citellus undulatus), which contained these peptides; there were increases in orientational reactions, increases in the frequency of stereotypical scratching movements, grooming, yawning, hiccuping, ... | 1998 | 9604218 |
| [the myoglobin level in skeletal muscles of the hibernating iakutiia ground squirrel citellus undulatus]. | many characteristics of the ground squirrel metmyoglobin (mb) were found to be similar to those of the pig and different from the whale ones. the mb content in winter time was 2.5-3.0-fold higher in hibernating and arousing ground squirrels than in alert ones. this seems to be connected with the high demand of oxygen in the muscles at the first stage of arousal. | 1998 | 9785422 |
| comparative characteristics of sarcoplasmic reticulum preparations from skeletal muscles of the ground squirrel spermophilus undulatus, rats, and rabbits. | a comparison of sarcoplasmic reticulum (sr) preparations from skeletal muscles of ground squirrels spermophilus undulatus, rats, and rabbits established that on the basis of protein yield and phospholipid/protein ratio these preparations are practically the same. nevertheless, the specific activity of ca-atpase, the main protein component of sr membranes, in sr preparations of the ground squirrel skeletal muscles is only about half of the activity in sr preparations of rats and rabbits. signific ... | 1999 | 10611529 |
| ca-atpase activity and protein composition of sarcoplasmic reticulum membranes isolated from skeletal muscles of typical hibernator, the ground squirrel spermophilus undulatus. | ca-atpase activity in sarcoplasmic reticulum (sr) membranes isolated from skeletal muscles of the typical hibernator, the ground squirrel spermophilus undulatus, is about 2-fold lower than that in sr membranes of rats and rabbits and is further decreased 2-fold during hibernation. the use of carbocyanine anionic dye stains-all has revealed that ca-binding proteins of sr membranes, histidine-rich ca-binding protein and sarcalumenin, in ground squirrel, rat, and rabbit sr have different electropho ... | 2001 | 12166830 |
| [characteristics of force-frequency relations in the myocardium of the squirrel citellus undulatus]. | the force-frequency relationship (ffr) in papillary muscles of the heart of active ground squirrel in different seasons was studied. for comparison, similar preparations from rat and rabbit were used. it was shown that the ffr of papillary muscles of active ground squirrel undergo significant seasonal changes. in summer and a part of autumn squirrels, a negative staircase (a decrease in the isometric force with increasing stimulation frequency) similar to that in adult rat was revealed. the ffr ... | 2002 | 12298215 |
| [the behavior of titin and the proteins of its family from skeletal muscles of ground squirrel (citellus undulatus) during hibernation and rats under conditions of simulated microgravity]. | by the use of sds page, the behavior of titin and mybp-c in fast (m. psoas) as well as titin and mybp-x in slow (m. soleus) muscles of ground squirrels (citellus undulatus) during hibernation was compared with the behavior of titin and mybp-x in rat m. soleus under conditions of simulated microgravity. a decrease in the amount of titin 1 and mybp-c relative to that of myosin heavy chains by approximately 30% and approximately 40%, correspondingly, in muscles of hibernating and arousing ground sq ... | 2004 | 15612538 |
| [relationships of parasitic triad co-members in a tuva natural plague focus: environmental and physiological aspects (experimental studies)]. | long-term experimental studies of the environmental and physiological aspects of relationships of parasitic triad co-members, performed in a tuva natural plague, by using citellophilus tesquorum altaicus fleas, their natural feeder--a long-tailed siberian souslik (citellus undulatus), and the yersinia pestis strain i-3226 that is typical of the focus were analyzed. a complex of biotic (the environmental features of a causative agent, avector, and a carrier) and abiotic (air temperature and moist ... | 2004 | 15689135 |
| hibernator citellus undulatus maintains safe cardiac conduction and is protected against tachyarrhythmias during extreme hypothermia: possible role of cx43 and cx45 up-regulation. | most mammals experience cardiac arrest during hypothermia. in contrast, hibernators remain in sinus rhythm even at body temperatures of 0 degrees c. | 2005 | 16171752 |
| [alteration in activity of protein synthesis system in brain neurons of citellus undulatus at hibernation and hypothermia]. | | 2006 | 16808282 |
| [the effect of hypothermia on the wavelength and vulnarability to ventricular arrhythmias in mammals]. | arrhythmias developing in isolated langendorff-perfused heart following the cooling of the perfusion solution from +37 to +3 degrees c were studied in rats and winter hibernating ground squirrels citellus undulatus with application of no drugs. in rats, hypothermia significantly increased the probability of ventricular arrhythmias (from 22 +/- 6 % at 37 degrees c to 56 +/- 14 % at 17 degrees c). excitation failure was observed in the rat hearts below 10 +/- 1 degrees c. the appearance of arrhyth ... | 2007 | 17598472 |
| the brain 5-ht1a receptor gene expression in hibernation. | hibernation is a unique physiological state characterized by profound reversible sleep-like state, depression in body temperature and metabolism. the serotonin 5-hydroxytryptamine(1a) (5-ht(1a)) receptor gene sequence in typical seasonal hibernator, ground squirrel (spermophilus undulatus), was specified. it was found that the fragment encoding the fifth transmembrane domain showed 93.6% of homology with the analogous fragment of the mouse and rat genes and displayed 88.5% homology with the huma ... | 2008 | 17711450 |
| electrophysiological mechanisms of antiarrhythmic protection during hypothermia in winter hibernating versus nonhibernating mammals. | robust cell-to-cell coupling is critically important in the safety of cardiac conduction and protection against ventricular fibrillation (vf). hibernating mammals have evolved naturally protective mechanisms against vf induced by hypothermia and reperfusion injury. | 2008 | 18984537 |
| [comparative study of cardiac alternans of action potential duration in hypothermia in rabbits and ground squirrels]. | cardiac alternans is a promising predictor of sudden death, yet its role in the mechanism of hypothermic arrhythmia induction is unclear. we aimed to investigate the effect of hypothermia on spatial-temporal characteristics of repolarization pattern in the langendorff-perfused hearts of summer active (sa, n = 6) and winter hibernating (wh, n = 7) ground squirrels spermophilus undulatus and rabbits (n = 5), who were immobilized with the excitation-contraction uncoupler bdm (10 mm) and optically m ... | 2009 | 19569529 |
| [human factors caused the third plague epidemic in harbin.] | the third plague epidemic in harbin broke out in 1946 and ended in 1954. different from the first two plague epidemics (imported), the third prevalence was both imported and idiopathic infectious disease which was caused by human factors. japanese troops set forbidden zones to build a biological weapon center, which destroyed the natural environment and offered a good growth condition for citellus undulatus. in 1945, on the eve of surrender, the japanese blew up the unit 731 germ factory located ... | 2011 | 21624272 |
| [Detection of leptospirosis infection in certain wild and domestic animals in Mongolia]. | Serological examination for leptospirosis of domestic and certain species of wild animals in Mongolia. | 2011 | 22145347 |
| analysis of the causes of the suppression of oxidative phosphorylation and energy-dependent cationic transport into liver mitochondria of hibernating gophers, citellus undulatus. | 1. the causes of the suppression of oxidative phosphorylation and energy-dependent cationic transport into liver mitochondria of hibernating gophers have been analysed. 2. the decrease of the atp synthesis rate and suppression of the energy-dependent k(+)- and ca(2+)-transport into mitochondria during hibernation has been found to be mainly related to a delta psi decrease in mitochondria of hibernating gophers. 3. the increase delta psi upon incubation of the mitochondria of hibernating animals ... | 2006 | 1458849 |
| [the intensity of oxidative phosphorylation and the function of the adenylate system in the liver mitochondria of active and hibernating susliks citellus undulatus]. | the state of adenylate system and intensity of oxidative phosphorylation in liver mitochondria of active and hibernating ground squirrels were studied depending on the concentration of extramitochondrial ca2+ ([ca2+]ex). it was shown that at [ca2+]ex.10(-7) m, the content of atp as well as atp/adp ratio are slightly lower in the mitochondria of hibernating ground squirrels than in the mitochondria of active animals. the other parameters of the adenylate system under the same conditions differ in ... | 2008 | 2596204 |
| comparative analysis of complete genome sequences of european subtype tick-borne encephalitis virus strains isolated from ixodes persulcatus ticks, long-tailed ground squirrel (spermophilus undulatus), and human blood in the asian part of russia. | tick-borne encephalitis virus (tbev) is divided into three subtypes: european (tbev-eu), siberian (tbev-sib), and far eastern (tbev-fe) subtypes. the geographical range of tbev-eu dominates in europe, but this subtype is present focally across the whole non-tropical forested eurasian belt, through russia to south korea. however, the tbev-eu strains isolated outside europe remain poorly characterized. in this study, full-genome sequences of eight tbev-eu isolates were determined. these strains we ... | 2017 | 28336423 |
| [reservation forms of plague infectious agent in tuva natural focus]. | data characterizing the reservation forms of plague infectious agent in tuva natural focus are presented in the review. yersinia pestis was shown to persist most of the year in citellophilus tesquorum altaicus imago --the main carrier, getting into the animal organism only for a short time. an increased ability to aggregate in autumn and accumulate in clumps of c. tesquorum altaicus females that are more adapted to survive the cold season compared with males promote the persistence of the microo ... | 2012 | 23163049 |
| eimeria yukonensis n. sp. (protozoa: eimeriidae) from the arctic ground squirrel spermophilus undulatus. | | 1969 | 5817318 |
| [functional similarity of the p-2 form of primary sleep and hypobiosis in the frog rana temporaria (based on data from luminescent microspectral analysis of the cytoplasm of neurosecretory neurons)]. | using luminescent microspectral analysis of preparations stained by acridine orange, studies have been made on the ratio between single- and double-stranded parts in ribosomal rna from the cytoplasm of neurosecretory neurones of the preoptic nucleus of the frog rana temporaria. the animals were investigated in active period, during p-2 form of the primary sleep, in hypobiosis, and after injection of the active factor (peptide fraction with a molecular mass 1-10,000 da) extracted from the small i ... | 2015 | 2471377 |
| implications of hybridization, numts, and overlooked diversity for dna barcoding of eurasian ground squirrels. | the utility of dna barcoding for species identification and discovery has catalyzed a concerted effort to build the global reference library; however, many animal groups of economical or conservational importance remain poorly represented. this study aims to contribute dna barcode records for all ground squirrel species (xerinae, sciuridae, rodentia) inhabiting eurasia and to test efficiency of this approach for species discrimination. cytochrome c oxidase subunit 1 (coi) gene sequences were obt ... | 2015 | 25617768 |
| lipids of liver membrane structures during hibernation of the arctic ground squirrel spermophilus undulatus. | | 2017 | 23478979 |
| seasonal effects of selank on the behavior of hibernating animals. | we studied the seasonal effects of peptide preparation selank on orientation and exploratory activity in 36 arctic ground squirrels citellus undulatus in the open-field and hole-board tests. selank most significantly increased behavioral activity of hibernating animals in the spring and fall. the test peptide had no effect on locomotor activity of animals. the selective stimulatory effect of selank on exploratory behavior of hibernating animals was season-dependent. the maximum effect was observ ... | 2005 | 16848230 |
| a reinvestigation of hemoglobin alterations in ground squirrels while in various hibernation activity states. | characterization of the hemoglobins of winter-hibernating, winter-active and summer-active arctic ground squirrels (citellus undulatus) by citrate agar electrophoresis and isoelectric focusing (ief), ph 5.5-8.5, showed no differences in hemoglobin electrophoretic patterns. previous studies showing alterations in hemoglobins were most likely the result of artifacts due to the use of whole blood. the arctic ground squirrel's hemoglobin amino terminal sequence was determined for each activity state ... | 1986 | 3709113 |
| standard operative temperatures and cost of thermoregulation in the arctic ground squirrel, spermophilus undulatus. | body temperatures (t b) and daily activity patterns of free-living arctic ground squirrells (spermophilus undulatus) were determined via telemetry at a field site in northern alaska. simultaneous measurements were made of ambient temperature (t a), wind speed (v), and incident solar radiation. the operative environmental temperature (t e) for ground squirrels was obtained from fur-covered, thin metal taxidermic models of the animals. standard operative temperature (t es), a comparative index of ... | 1981 | 28310004 |
| seasonal changes in body composition of the arctic ground squirrel, citellus undulatus. | | 1976 | 1253012 |
| gluconeogenesis in arctic ground squirrels between periods of hibernation. | the hibernation season in the arctic ground squirrel (citellus undulatus) is broken into 8- to 18- day cycles by short homeothermal periods during which the carboydrate reserves depleted during hibernation are replenished. this study follows a number of metabolities in tissues and body fluids to assess the sources for reconstitution of the glucose reserves: lactate, urea, ammonia, free fatty acid, glycerol, triglyceride, and glucose in plasma; glycogen in liver and muscle; and urea and ammonia n ... | 1975 | 1147024 |
| seasonal variation in blood viscosity of the hibernating arctic ground squirrel (spermophilus undulatus plesius). | | 1973 | 4145778 |
| characteristics of arctic ground squirrel alarm calls. | arctic ground squirrels, citellus undulatus, produce six distinctly different sounds. each of these sounds may represent a signal in itself, but combinations of these acoustic elements or repetition of a single element produce additional signals. several of these signals serve as alarm calls. one sound element consists of a short (0.05 sec) broad frequency chat while another is a longer (0.16 to 0.25 sec) descending narrow frequency whistle. squirrels utter three-note chatter calls when approach ... | 1971 | 28309781 |
| further studies of transferrins of the arctic ground squirrel spermophilus undulatus (rodentia: sciuridae). | | 1970 | 5511563 |
| comparative histological studies of the stomach, small intestine, and colon of warm and active and hibernating arctic ground squirrels, spermophilus undulatus. | | 1958 | 13583559 |
| comparative histochemistry of selected tissues from active and hibernating arctic ground squirrels, spermophilus undulatus. | | 1957 | 13513672 |
| seasonal changes in proteolytic activity of calpains in striated muscles of long-tailed ground squirrel spermophilus undulatus. | seasonal changes in proteolytic activity and content of calpains in striated muscles of the longtailed ground squirrel spermophilus undulatus were studied by casein zymography and western blotting analysis. the results testify to hyperactivation of calpain proteases in the skeletal muscles of awakened animals during the "winter" activity. the observed changes are discussed in the context of adaptation of skeletal muscles of long-tailed ground squirrels to hibernation. | 2017 | 28421435 |
| [hypothermia induced alteration of refractoriness in the ventricular myocardium of ground souirrel citellus undulatus]. | bioelectrical activity and refractoriness in ventricular myocardium of the hibernator--ground squirrel citellus undulatus were investigated during hypothermia. experiments were performed with use of isolated, perfused preparations of papillary muscle from right ventricular. preparations were obtained from hibernating (hs), summer active (sas) squirrels and from rats. bioelectrical activity was registered using the standard microelectrode technique at 37-17 degrees c. action potentials duration ( ... | 2014 | 25936179 |
| [seasonal changes in mechanical resistance of erythrocytes of the long-tailed ground squirrel (citellus undulatus)]. | seasonal changes of relative blood reticulocyte counts, free plasma hemoglobin and mechanical erythrocyte resistance were studied in the long-tailed ground squirrel (citellus undulatus), under different functional conditions (winter hibernation, forced arousal in winter, and summer activity). a significant increase in reticulocyte counts in the ground squirrel blood was observed in april and october, indicating enhancement of erythropoeisis. this conclusion is also confirmed by a significant inc ... | 2015 | 25786319 |
| [seasonal peculiarities of the ground squirrel (spermophilus undulatus) and wistar rats circadian activity]. | the seasonal peculiarities of the circadian activity of hibernator, yakutian long tail ground squirrels (s. undulatus) (n = 35) and non hibernator, wistar rats (n = 35), were studied. the locomotor activity was registered in each subject individually during 5-17 days by means of "animex" in the different periods of annual cycle. it was shown that ground squirrels were animals with daily type of activity. on the contrary, the wistar rats demonstrated nocturne type of locomotors activity. the acti ... | 2014 | 25697015 |
| regulation of glucokinase activity in liver of hibernating ground squirrel spermophilus undulatus. | the kinetic properties of glucokinase (glk) from the liver of active and hibernating ground squirrels spermophilus undulatus have been studied. entrance of ground squirrels into hibernation from their active state is accompanied by a sharp decrease in blood glucose (glc) level (from 14 to 2.9 mm) and with a significant (7-fold) decrease of glk activity in the liver cytoplasm. preparations of native glk practically devoid of other molecular forms of hexokinase were obtained from the liver of acti ... | 2014 | 25108335 |
| [seasonal changes in the isoform composition of the myosin heavy chains in skeletal muscles of hibernating ground squirrels spermophilus undulatus]. | seasonal changes of the isoform composition of myosin heavy chains in skeletal muscles (m. triceps, m. longissimus dorsi, m. soleus, m. gastrocnemius, m. vastus lateralis) of hibernating ground squirrels spermophilus undulatus were studied. functional properties of myosin (the actin-activated atpase activity and its ca(2+)-sensitivity in vitro) were also examined. it was observed that the content of slow myosin heavy chain i isoform increased and the content of fast iix/d isoform decreased in mu ... | 2013 | 23272578 |
| hypothermia-induced spatially discordant action potential duration alternans and arrhythmogenesis in nonhibernating versus hibernating mammals. | the heart of hibernating species is resistant to lethal ventricular fibrillation (vf) induced by hypothermia. spatially discordant (sda) cardiac alternans is a promising predictor of vf, yet its role in the mechanism of hypothermic arrhythmogenesis in both nonhibernating and hibernating mammals remains unclear. we optically mapped the posterior epicardial surface of langendorff-perfused hearts of winter hibernating (wh, n = 13), interbout arousal (iba; n = 4), and summer active (sa, n = 6) groun ... | 2012 | 22886418 |
| [host influence on the frequency of block formation in males and females of citellophilus tesquorum altaicus ioff, 1936 (siphonaptera: ceratophyllidae) and transmission the plague pathogen by these fleas]. | data obtained during feeding of citellophilus tesquorum aitaicus ioff, 1936 infested females and males (siphonaptera: ceratophyllidae), the main vectors of plague in tuva natural plague locus, on the natural host and laboratory animal was analyzed. it was found that sexual differences in fleas depended on the type of the host. females fed more actively on the longtailed ground citellus undulatus than on white mouse. alimentary activity of males on these animals was similar. higher mortality of f ... | 2012 | 22834346 |
| seasonal changes in microsomal fraction enriched with na,k-atpase from kidneys of the ground squirrel spermophilus undulatus. | the na,k-atpase activity in microsomal fraction isolated from kidneys of winter hibernating ground squirrels was found to be 1.8-2.0-fold lower than that in active animals in summer. this is partially connected with a decrease in na,k-atpase protein content in these preparations (by 25%). using antibodies to different isoforms of na,k-atpase α-subunit and analysis of enzyme inhibition by ouabain, it was found that the decrease in na,k-atpase activity during hibernation is not connected with chan ... | 2010 | 21314610 |
| ornithine decarboxylase in the liver, spleen, and bone marrow of ground squirrels spermophilus undulatus. | | 2017 | 20714860 |
| [disproportionate eruption of maxillary and mandibular incisors in the long-tailed ground squirrel]. | abstract-the surface of the maxillary and mandibular incisors of spermophilus undulatus long-tailed ground squirrels, including those born in the current year and those that have hibernated (trapped one month or later after hibernation) is studied. the presence of daily growth on the incisors' surface allows the evaluation of their eruption rate; a specific change in the character of the incisors' eruption corresponds to winter hibernation (hibernation zone), which serves as the time mark. corre ... | 2010 | 20583628 |
| high genetic diversity in the long-tailed ground squirrel (spermophilus undulatus) population on olkhon island: a natural gene bank or the consequences of long-term isolation? | | 2017 | 20170063 |
| the seasonal peculiarities of force-frequency relationships in active ground squirrel spermophilus undulatus ventricle. | the plasticity of calcium homeostasis is of crucial importance for the unique ability of the hibernators' heart to function under conditions of body temperature changing from 37 degrees c to near freezing point. however, the precise mechanism of calcium homeostasis regulation in these animals is largely unknown. force-frequency relationship, as an indicator of participation of various sources of calcium (external and intracellular) in the activation of contraction, and post-rest potentiation as ... | 2007 | 17803987 |
| [seasonal changes in phosphorylation of myosin regulatory light chains and c-protein in myocardium of hibernating ground squirrel citellus undulatus]. | a comparative study concerning the extent of phosphorylation of myosin regulatory light chains and c-protein from the left ventricle of hibernating ground squirrel citellus undulatus during the periods of hibernation and activity was carried out. during hibernation, regulatory light chains of ground squirrel were found to be completely dephosphorylated. in active animals, the share of phosphorylated light chains averages 40-45% of their total amount. the extent of phosphorylation of the cardiac ... | 2006 | 17131836 |
| [myosin light chains of skeletal and cardiac muscles of ground squirrel citillus undulatus in different periods of hibernation]. | the isoform composition of myosin light chains and the extent of their phosphorylation in skeletal and cardiac muscles of ground squirrel citellus undulatus in different periods of hibernation were studied. regulatory myosin light chains of skeletal muscles of hibernating ground squirrels were completely dephosphorylated, while 25% of these light chains in active animals were phosphorylated. during hibernation, a shift of isoform composition of essential and regulatory skeletal muscle myosin lig ... | 2006 | 16248153 |
| [pattern of excitation in isolated heart of hibernator ground squirrel citellus undulatus]. | aim of our study was to measure conduction velocity and pattern of excitation during hypothermia in hearts of ground squirrels citellus undulatus, known to be most resilient hibernators. we imaged electrical conduction in intact isolated hearts of summer active and winter hibernating ground squirrels at temperatures varying from +37 degrees c to +3 degrees c. electrical activity was mapped using ccd camera (500 frames/sec) and voltage-sensitive dye di-4-anepps during normal sinus rhythm and vent ... | 2005 | 15940184 |
| [the evaluation of the sizes of erythrocytes of the hibernating ground squirrel citellus undulatus pallas]. | a topographical image of individual erythrocytes of the ground squirrel citellus undulatus pallas, in unfixed unstained smears was first obtained by scanning probe microscopy for two states of the animal: hibernation and the active state. the scannig of single discocytes, i.e. erythrocytes having a typical discal form, was fulfilled. for the active male, the diameter of the discocyte was found to be approximately 6500 nm. for the hibernating female, the diameter is approximately 6000 nm. accordi ... | 2006 | 15857003 |
| the roles of monoamine oxidase form a (mao a) and no synthase in the mechanisms of the emergence from hibernation in the ground squirrel citellus undulatus. | | 2017 | 15587799 |
| 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. | | 2017 | 15523828 |
| effect of insulin on the myocardial force-frequency relationship in the siberian ground squirrel citellus undulatus during winter arousal. | | 2017 | 15378909 |
| [adaptive behavior of titin isoforms from skeletal and cardiac muscles of ground squirrels (citellus undulatus) during hibernation]. | by the use of modified sds electrophoresis in agarose-strengthened 2% polyacrylamide gels, the adaptive behavior of titin isoforms in skeletal and cardiac muscles of ground squirrels (citellus undulatus) during hibernation was studied. the presence of two titin isoforms (short and long) with molecular weights approximately 3700 and approximately 3800 kda in m. soleus, approximately 3400 and approximately 3600 kda in m. psoas, approximately 3000 and approximately 3400 kda in the left ventricle of ... | 2013 | 15327202 |
| [specifics of monoaminergic regulation of the central nervous system of hibernating animals (citellus undulatus)]. | seasonal features of open-field behavior of yakut ground squirrels (citellus undulatus) and changes in the brain mao a activity were studied. it was found that all parameters of exploratory activity in the open field and holeboard test reached the values characteristic of summer animals very rapidly, within a few days or (in some cases) even within the first 24 hours after the arousal from hibernation in the middle of april. in autumn these parameters decreased to their minimum values 1.5-2 mont ... | 2013 | 15174262 |
| role of lipids in the assembly of endoplasmic reticulum and dictyosomes in neuronal cells from the cerebral cortex of yakutian ground squirrel (citellus undulatus) during hibernation. | phospholipids and cholesterol were assayed in homogenates and microsomal fractions from the cerebral cortex of summer-active, winter-torpid, and winter-active yakutian ground squirrels (citellus undulatus). ultrastructural analysis of both microsomal fraction and intact neurons was performed by serial ultramicrotomy. the levels of sphingomyelin (sm), phosphatidylserine (ps), and phosphatidylethanolamine (pea) were decreased in homogenates from the cerebral cortex of winter ground squirrels compa ... | 2003 | 12946261 |
| [phosphorylation of sarcomeric cytoskeletal proteins--an adaptive factor for inhibiting the contractile activity of muscle during hibernation]. | the influence of phosphorylation in vitro of the sarcomere cytoskeletal proteins titin and x-protein of skeletal muscles as well as c-protein of cardiac muscle of ground squirrel citellus undulatus on the actin-activated atpase activity of myosin and its ca2+ sensitivity was studied. it was shown that phosphorylation lowers the activating effect of titin and c-protein and increases the inhibitory effect of x-protein on the enzymatic properties of actomyosin. the phosphorylation of the proteins h ... | 2006 | 12815860 |
| seasonal changes of ca-atpase activity in skeletal muscle sarcoplasmic reticulum of the ground squirrel spermophilus undulatus. | | 2003 | 12763887 |
| [properties of c protein from skeletal and cardiac muscles of the ground squirrel citellus undulatus at various stages of hibernation]. | changes in the molecular weight and functional properties of the c and x proteins from skeletal muscles and the c protein from the cardiac muscle of hibernating ground squirrels citellus undulatus at different stages of the hibernation were studied. a decrease in the molecular weight of the c protein from fast fibers of skeletal muscles of hibernating ground squirrels compared with awakening and active animals was revealed. the appearance of shorter molecules of the c protein upon hibernation wa ... | 2013 | 12298210 |
| [seasonal changes in tumor necrosis factor production in hibernating animals in normal conditions and under the effects of electromagnetic and ionizing radiation]. | production of tumor necrosis factor (tnf) has been investigated in peritoneal macrophages and splenic t cells of arctic yakutian ground squirrel (citellus undulatus pallas) upon in vitro action of electromagnetic and ionizing radiation during annual cycle. the significant activation of tnf production in the cells of awaken ground squirrels in winter and increasing level of the lymphokine production at spring-summer period has been indicated. the level of tnf production in splenic t cells was not ... | 2016 | 12004607 |
| seasonal peculiarities of behavior of ground squirrel citellus undulatus in holeboard and open field tests. | seasonal changes in the behavior of ground squirrels citellus undulatus (n=35) in holeboard and open field tests were studied. it was found that the number of head dips and rearings in the holeboard and the number of crossed squares, rearings, and runs across the field center in the open field in ground squirrels during arousal between bouts at the end of the hibernation period, in the middle of march, were lower than these indices in active summer animals. a rapid restoration of all behavioral ... | 2001 | 11738511 |
| frequency-dependent effect of insulin on myocardial contractility in active ground squirrel citellus undulatus in different seasons. | | 2017 | 11727566 |
| seasonal specificity of the frequency-force dependence in the myocardium of ground squirrel, citellus undulatus. | | 2017 | 11712148 |
| characteristics of sarcoplasmic reticulum membrane preparations isolated from skeletal muscles of active and hibernating ground squirrel spermophilus undulatus. | the total ca-atpase activity in the sarcoplasmic reticulum (sr) membrane fraction isolated from skeletal muscles of winter hibernating ground squirrel spermophilus undulatus is approximately 2.2-fold lower than in preparations obtained from summer active animals. this is connected in part with approximately 10% decrease of the content of ca-atpase protein in sr membranes. however, the enzyme specific activity calculated with correction for its content in sr preparations is still approximately 2- ... | 2001 | 11566064 |
| [analysis of changes in heart rate and temperature of the ground squirrel citellus undulatus in various physiological states]. | heart rate (hr) of ground squirrel c. undulatus was studied in dependence of season, level of activity, physiological state and air temperature (t). in summer hr varies from 110-130 beat/min in sleep up to 420 beat/min at flight from danger. during winter hibernation hp was minimal (3-5 beat/min) at t 1-4 degrees c, the increase in t induced the growth of hp in correspondence to the arrenius van't hoff law. the temperature of the body in hibernation exceeded t on 1.5-3 degrees c. the time of get ... | 2006 | 11236592 |
| production of tumor necrosis factor in cells of hibernating ground squirrels citellus undulatus during annual cycle. | tnf production has been studied in peritoneal macrophages and splenic t cells of arctic yakutian ground squirrel (citellus undulatus pallas) in hibernating and awake animals in winter and in prehibernating autumn as well as in active euthermic spring-summer animals. a high level of tnf production in macrophages of ground squirrel is observed over the active period and during arousals in winter. there are no significant season variations in tnf production in splenic t lymphocytes of ground squirr ... | 2000 | 10954040 |
| [the state-dependent action of neuropeptides and monoamines on the background neuronal activity of the medial septal area in hibernating animals]. | neuronal activity of the medial septal area (ms-db) was recorded extracellularly in brain slices from two groups of yakutian ground squirrels citellus undulatus--hibernating (winter period) and actively waking (summer period). effects of three neuropeptides identified in the brain of hibernators (tskyr, tsky, and dy) and of two monoamines (serotonin and noradrenaline) on spontaneous activity were analyzed. all neuropeptides reversibly changed the levels of the background activity, but in the hib ... | 2013 | 10822842 |
| [effect of insulin on the myocardium of the active, hibernating and wakening ground squirrel citellus undulatus]. | the effect of insulin (0.1-100 nm) on isometric force of contraction in isolated ground squirrel papillary muscle was investigated. in summer, autumn and winter active animals, insulin had a negative inotropic effect on papillary muscles, decreasing the amplitude of contraction by about 30% of the control value. in some cases, predominantly in the summer group of animals, insulin produced different effects on contractility: low doses (0.1-0.5 nm) caused a transient activation of isometric contra ... | 2014 | 10776550 |
| [the epizootiological role of the population organization of the stock of fleas on the long-tailed suslik in a natural focus of plague in tuva]. | spatial location of epizootic events in the tuva plague focus is determined at a considerable degree by the population structure of the flea citellophilus tesquorum--the main plague microbe vector. within the enzootic territory occupied by five populations of the long-tailed ground squirrel (citellus undulatus) there are six populations of c. tesquorum. each population of fleas has a corresponding autonomic plague focus. various conditions for the microbe life activity in these populations are r ... | 2010 | 10771772 |
| ultrastructure of taste receptor cells in active and hibernating ground squirrels. | differences in taste bud ultrastructure between active and low-temperature hibernation states were investigated in the siberian ground squirrel, citellus undulatus. compared to active summer animals, taste bud volume and the morphology of the taste pore showed little change while an animal was hibernating. however, impressive differences were observed in nuclei and cytoplasmic organelles of all cells within taste buds. in low-temperature hibernation the nucleoli of elongated, non-dark cells had ... | 1999 | 10742960 |
| state-dependent effects of some neuropeptides and neurotransmitters on neuronal activity of the medial septal area in brain slices of the ground squirrel, citellus undulatus. | neuronal activity of the medial septal area was recorded extracellularly in brain slices taken from hibernating (winter) and waking (summer) ground squirrels. the effects of neuropeptides identified in the brain tissue of hibernators (thr-ser-lys-tyr, thr-ser-lys-tyr-arg and asp-tyr) on the background activity and responses to electrical stimulation of the median forebrain bundle were analysed. for comparison, the effects of bath application of noradrenaline and serotonin were also tested. spont ... | 2000 | 10727797 |
| 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 ... | 1999 | 10605065 |
| [the cardiotropic activity of the nucleotides found in the composition of the low-molecular peptide subfraction obtained from the brain of hibernating susliks citellus undulatus]. | | 2014 | 10519201 |
| [the van't hoff rule in studying various phases of hibernation of the squirrel citellus undulatus pallas. physico-chemical route to cold adaptation]. | taking into account the van't hoff's law the rates of relative erythrocyte hemolysis in ground squirrel citellus undulatus pallas during different phases of hibernation were first studied by the method of acid erythrograms with some modifications. the temperature of the erythrogram registration (8 degrees c) models the body temperature in hibernation, and temperature of 35 degrees c, corresponds to the body temperature of the awakened ground squirrel. the positions of the erythrogram maxima for ... | 2008 | 10079928 |
| [seasonal changes in the composition and functions of myosin filaments of the skeletal muscles of ground squirrels citellus undulatus during hibernation]. | the ability of hibernating and arousing ground squirrels' myosins to bind the key enzyme of glycolysis was found to be significantly lower than that of active animals. the findings suggest considerable changes in the myosin heavy and light chain composition occurring during hibernation, as well as a major contribution of the myosin in inhibiting the contractile ability of the skeletal muscles during hibernation. | 2016 | 9541966 |
| [the action of insulin on cardiac contractility in active, hibernating and arousing susliks citellus undulatus]. | during the deep hibernation (at 5-6 degrees c of the heart temperature) and during arousal from hibernation (at 15-16 degrees c) insulin have no effect on contractility. two opposite inotropic effects of insulin at concentrations 0.1-50 nm were found at higher temperature of arousing: a transient positive inotropic effect between 21-28 degrees c, and a negative one (about 20-30% from the control value) above 28 degrees c. in active summer and winter animals insulin produced mainly the negative i ... | 2011 | 9490118 |
| [atpase and regulatory properties of skeletal muscle myosin in citellus undulatus susliks during various stages of winter hibernation]. | the paper is devoted to the study on enzymatic and regulatory properties of skeletal muscle myosin of hibernating ground squirrels (citellus undulatus) for the purpose of elucidating the contribution of myosin and myosin filaments to the change of physiological state of the animal at the different stages of hibernation (hibernation, arousing, winter activity). it has been revealed that actin-activated atpase activity of myosins of hibernating and arousing ground squirrels is less by 60 and 20%, ... | 2009 | 9172677 |
| seasonal changes in myoglobin content in muscles of hibernating yakutian ground squirrels. | myoglobin content in skeletal muscles of the yakutian ground squirrel citellus undulatus was measured during different periods of the annual life cycle: in active animals in summer, and in hibernating and awake animals in winter. it was found that the mb content in winter, irrespective of the state of the animal (hibernating or awake), is 2.5-3-fold higher than in summer. analysis of biochemical data available in the literature suggests that the increase in mb content in winter is most probably ... | 1997 | 9159866 |
| the kinetic characteristics of l-type calcium channels in cardiac cells of hibernators. 2. analysis of the kinetic model. | the present paper describes the experimental and theoretical investigations of the kinetic characteristics of the l-type ca2+ channels in ground squirrels citellus undulatus in two different physiological states (hibernation and spontaneous arousal). the perforated patch-clamp method was used in the experiments. we have shown in the previous study [1] that ca2+ currents in hibernating and active animals may be described by the d2f1(2)f2 model. based on that model, in this paper we studied in det ... | 1997 | 9354400 |
| the kinetic characteristics of the l-type calcium channels in cardiocytes of hibernators. 1. development of a kinetic model. | the present paper described the experimental and theoretical investigations of the kinetic characteristics of the l-type ca2+ channels in ground squirrels citellus undulatus in two different physiological states (hibernation and spontaneous arousal). the perforated patch-clamp method was used in the experiments. it is shown that the potential-dependent ca2+ current in isolated cardiocytes from hibernating animals is strongly inhibited during hibernation. an attempt was made to describe the kinet ... | 1997 | 9257280 |
| comparative analysis of the kinetic characteristics of l-type calcium channels in cardiac cells of hibernators. | an undefined property of l-type ca2+ channels is believed to underlie the unique phenotype of hibernating hearts. therefore, l-type ca2+ channels in single cardiomyocytes isolated from hibernating versus awake ground-squirrels (citellus undulatus) were compared using the perforated mode of the patch-clamp technique, and interpreted by way of a kinetic model of ca2+ channel behavior based upon the concept of independence of the activation and inactivation processes. we find that, in hibernating g ... | 1996 | 8789095 |
| [changes in structural organization of reorganized myosin filaments from skeletal muscles of the winter-hibernating suslik citellus undulatus during awakening]. | electron microscopic observations of myosins, isolated from skeletal muscles of ground squirrels at the different states (hybernation-mhyb; winter activity--m(act); the beginning of arousal-m(begin); the end of arousal-m(end)) have revealed the differences in the structure of their filaments. the filaments reconstituted from mhyb, m(act) and m(end) (rectal temperature 27 degrees c) exhibit the ordered structure with the myosin heads arranged regularly (period of 14.3 nm) on the filament surface. ... | 2009 | 8714465 |
| [daily and seasonal changes in temperature and cardiac rhythm of the long-tailed squirrel, citellus undulatus]. | | 1995 | 8535271 |
| [biologically active substances in the tissues of hibernating animals]. | it was supposed that the transitional period from euthermia to hibernation rather than the period of winter hibernation is optimal for the secretion of biologically active substances in rodent tissues. this hypothesis was tested in experiment. the maximal o2 consumption suppression was noted in mice after i. p. injection of blood plasma from suslik citellus undulatus at the beginning of its entering into hibernation. low-molecular peptide fraction appearance in c. undulatus blood before hibernat ... | 2013 | 7483833 |
| the mechanism of calcium-dependent activation of respiration of liver mitochondria from hibernating ground squirrels, citellus undulatus. | 1. it is shown that ca(2+)-dependent activation of respiration of liver mitochondria from hibernating ground squirrels is accompanied by mitochondrial swelling. 2. the swelling of mitochondria from hibernating ground squirrels, as well as the activation of mitochondrial respiration, is precluded by cyclosporin a, p-bromphenacylbromide and oligomycin. carboxyatractiloside, on the contrary, under these conditions favors the swelling and the acceleration of respiration. 3. it was concluded that ca( ... | 1993 | 8243063 |
| relationship between structure and function of liver mitochondria from hibernating and active ground squirrels, citellus undulatus. | 1. electron microscopy of liver tissue preparations, obtained from hibernating ground squirrels, reveals mitochondria in a condensed state. 2. when kept on ice, mitochondria isolated from the livers of hibernating and active ground squirrels are in a shrunken state. 3. incubation of mitochondria isolated from the livers of active ground squirrels in the presence of succinate, at 27 degrees c, results in mitochondrial swelling, while mitochondria from hibernating ground squirrels under the same c ... | 1993 | 8403844 |