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Sample records for 13-lined ground squirrel

  1. The hibernating 13-lined ground squirrel as a model organism for potential cold storage of platelets.

    PubMed

    Cooper, Scott T; Richters, Karl E; Melin, Travis E; Liu, Zhi-jian; Hordyk, Peter J; Benrud, Ryan R; Geiser, Lauren R; Cash, Steve E; Simon Shelley, C; Howard, David R; Ereth, Mark H; Sola-Visner, Martha C

    2012-05-15

    Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.

  2. Hibernation induces immune changes in the lung of 13-lined ground squirrels (Ictidomys tridecemlineatus).

    PubMed

    Bohr, Matthew; Brooks, Abigail R; Kurtz, Courtney C

    2014-12-01

    During hibernation, significant changes occur in the systemic and intestinal immune populations. We found that the lungs of hibernating 13-lined ground squirrels (Ictidomys tridecemlineatus) also undergo shifts in immune phenotype. Within the population of mononuclear cells, the percentage of T cells increases and the percentage of CD11b/c(+) cells decreases in hibernators. E-selectin, which promotes endothelial attachment, increases during arousal from torpor. Levels of the anti-inflammatory cytokine interleukin (IL)-10 in the lung are lower during hibernation while levels of the pro-inflammatory cytokine, tumor necrosis factor (TNF)-α remain constant. Expression of suppressor of cytokine signaling (SOCS) proteins is also decreased in torpid hibernators. Our data point to a unique immune phenotype in the lung of hibernating ground squirrels in which certain immunosuppressive proteins are downregulated while some potentially inflammatory proteins are maintained or amplified. This indicates that the lung houses an immune population that can potentially respond to antigenic challenge during hibernation.

  3. Impaired skeletal muscle regeneration in the absence of fibrosis during hibernation in 13-lined ground squirrels.

    PubMed

    Andres-Mateos, Eva; Mejias, Rebeca; Soleimani, Arshia; Lin, Brian M; Burks, Tyesha N; Marx, Ruth; Lin, Benjamin; Zellars, Richard C; Zhang, Yonggang; Huso, David L; Marr, Tom G; Leinwand, Leslie A; Merriman, Dana K; Cohn, Ronald D

    2012-01-01

    Skeletal muscle atrophy can occur as a consequence of immobilization and/or starvation in the majority of vertebrates studied. In contrast, hibernating mammals are protected against the loss of muscle mass despite long periods of inactivity and lack of food intake. Resident muscle-specific stem cells (satellite cells) are known to be activated by muscle injury and their activation contributes to the regeneration of muscle, but whether satellite cells play a role in hibernation is unknown. In the hibernating 13-lined ground squirrel we show that muscles ablated of satellite cells were still protected against atrophy, demonstrating that satellite cells are not involved in the maintenance of skeletal muscle during hibernation. Additionally, hibernating skeletal muscle showed extremely slow regeneration in response to injury, due to repression of satellite cell activation and myoblast differentiation caused by a fine-tuned interplay of p21, myostatin, MAPK, and Wnt signaling pathways. Interestingly, despite long periods of inflammation and lack of efficient regeneration, injured skeletal muscle from hibernating animals did not develop fibrosis and was capable of complete recovery when animals emerged naturally from hibernation. We propose that hibernating squirrels represent a new model system that permits evaluation of impaired skeletal muscle remodeling in the absence of formation of tissue fibrosis.

  4. Impaired Skeletal Muscle Regeneration in the Absence of Fibrosis during Hibernation in 13-Lined Ground Squirrels

    PubMed Central

    Soleimani, Arshia; Lin, Brian M.; Burks, Tyesha N.; Marx, Ruth; Lin, Benjamin; Zellars, Richard C.; Zhang, Yonggang; Huso, David L.; Marr, Tom G.; Leinwand, Leslie A.; Merriman, Dana K.; Cohn, Ronald D.

    2012-01-01

    Skeletal muscle atrophy can occur as a consequence of immobilization and/or starvation in the majority of vertebrates studied. In contrast, hibernating mammals are protected against the loss of muscle mass despite long periods of inactivity and lack of food intake. Resident muscle-specific stem cells (satellite cells) are known to be activated by muscle injury and their activation contributes to the regeneration of muscle, but whether satellite cells play a role in hibernation is unknown. In the hibernating 13-lined ground squirrel we show that muscles ablated of satellite cells were still protected against atrophy, demonstrating that satellite cells are not involved in the maintenance of skeletal muscle during hibernation. Additionally, hibernating skeletal muscle showed extremely slow regeneration in response to injury, due to repression of satellite cell activation and myoblast differentiation caused by a fine-tuned interplay of p21, myostatin, MAPK, and Wnt signaling pathways. Interestingly, despite long periods of inflammation and lack of efficient regeneration, injured skeletal muscle from hibernating animals did not develop fibrosis and was capable of complete recovery when animals emerged naturally from hibernation. We propose that hibernating squirrels represent a new model system that permits evaluation of impaired skeletal muscle remodeling in the absence of formation of tissue fibrosis. PMID:23155423

  5. Comfortably Numb and Back: Plasma Metabolomics Reveals Biochemical Adaptations in the Hibernating 13-Lined Ground Squirrel.

    PubMed

    D'Alessandro, Angelo; Nemkov, Travis; Bogren, Lori K; Martin, Sandra L; Hansen, Kirk C

    2017-02-03

    Hibernation is an evolutionary adaptation that affords some mammals the ability to exploit the cold to achieve extreme metabolic depression (torpor) while avoiding ischemia/reperfusion or hemorrhagic shock injuries. Hibernators cycle periodically out of torpor, restoring high metabolic activity. If understood at the molecular level, the adaptations underlying torpor-arousal cycles may be leveraged for translational applications in critical fields such as intensive care medicine. Here, we monitored 266 metabolites to investigate the metabolic adaptations to hibernation in plasma from 13-lined ground squirrels (57 animals, 9 time points). Results indicate that the periodic arousals foster the removal of potentially toxic oxidative stress-related metabolites, which accumulate in plasma during torpor while replenishing reservoirs of circulating catabolic substrates (free fatty acids and amino acids). Specifically, we identified metabolic fluctuations of basic amino acids lysine and arginine, one-carbon metabolism intermediates, and sulfur-containing metabolites methionine, cysteine, and cystathionine. Conversely, reperfusion injury markers such as succinate/fumarate remained relatively stable across cycles. Considering the cycles of these metabolites with the hibernator's cycling metabolic activity together with their well-established role as substrates for the production of hydrogen sulfide (H2S), we hypothesize that these metabolic fluctuations function as a biological clock regulating torpor to arousal transitions and resistance to reperfusion during arousal.

  6. Response of the JAK-STAT pathway to mammalian hibernation in 13-lined ground squirrel striated muscle.

    PubMed

    Logan, Samantha M; Tessier, Shannon N; Tye, Joann; Storey, Kenneth B

    2016-03-01

    Over the course of the torpor-arousal cycle, hibernators must make behavioral, physiological, and molecular rearrangements in order to keep a very low metabolic rate and retain organ viability. 13-lined ground squirrels (Ictidomys tridecemlineatus) remain immobile during hibernation, and although the mechanisms of skeletal muscle survival are largely unknown, studies have shown minimal muscle loss in hibernating organisms. Additionally, the ground squirrel heart undergoes cold-stress, reversible cardiac hypertrophy, and ischemia-reperfusion without experiencing fatal impairment. This study examines the role of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway in the regulation of cell stress in cardiac and skeletal muscles, comparing euthermic and hibernating ground squirrels. Immunoblots showed a fivefold decrease in JAK3 expression during torpor in skeletal muscle, along with increases in STAT3 and 5 phosphorylation and suppressors of cytokine signaling-1 (SOCS1) protein levels. Immunoblots also showed coordinated increases in STAT1, 3 and 5 phosphorylation and STAT1 inhibitor protein expression in cardiac muscle during torpor. PCR analysis revealed that the activation of these pro-survival signaling cascades did not result in coordinate changes in downstream genes such as anti-apoptotic B-cell lymphoma-2 (Bcl-2) family gene expression. Overall, these results indicate activation of the JAK-STAT pathway in both cardiac and skeletal muscles, suggesting a response to cellular stress during hibernation.

  7. Selective mobilization of saturated fatty acids in isolated adipocytes of hibernating 13-lined ground squirrels Ictidomys tridecemlineatus.

    PubMed

    Price, Edwin R; Armstrong, Christopher; Guglielmo, Christopher G; Staples, James F

    2013-01-01

    Fatty acids are not mobilized from adipocyte triacylglycerols uniformly but rather some are preferentially mobilized while others are preferentially retained. In many vertebrate species, the pattern of differential mobilization is determined by the physical and chemical properties of each fatty acid. Fatty acids with shorter chains and more double bonds tend to be more readily mobilized than others, a pattern observed both in whole-animal studies and in isolated adipocytes. Several hibernating species seem to break this pattern, however, and retain 18:2ω6 (linoleic acid) while mobilizing saturated fatty acids such as 18:0. We sought to confirm this pattern in adipocytes of a hibernator, the 13-lined ground squirrel Ictidomys tridecemlineatus, and to investigate mobilization patterns for the first time at hibernation temperature. We isolated adipocytes from summer active and winter torpid squirrels and incubated them with 1 μM norepinephrine at 4°C (7 h) and 37°C (90 min). We measured the proportion of each fatty acid in the adipose tissue and in the buffer at the end of incubation. Patterns of mobilization were similar in both seasons and incubation temperatures. Saturated fatty acids (18:0 and 16:0) were highly mobilized relative to the average, while some unsaturated fatty acids (notably, 18:1ω9 and 18:2ω6) were retained. We conclude that hibernators have unique mechanisms at the level of adipose tissue that preferentially mobilize saturated fatty acids. Additionally, we found that adipocytes from hibernating squirrels produced more glycerol than those from summer squirrels (regardless of temperature), indicating a higher lipolytic capacity in hibernating squirrels.

  8. Cytoskeletal regulation dominates temperature-sensitive proteomic changes of hibernation in forebrain of 13-lined ground squirrels.

    PubMed

    Hindle, Allyson G; Martin, Sandra L

    2013-01-01

    13-lined ground squirrels, Ictidomys tridecemlineatus, are obligate hibernators that transition annually between summer homeothermy and winter heterothermy - wherein they exploit episodic torpor bouts. Despite cerebral ischemia during torpor and rapid reperfusion during arousal, hibernator brains resist damage and the animals emerge neurologically intact each spring. We hypothesized that protein changes in the brain underlie winter neuroprotection. To identify candidate proteins, we applied a sensitive 2D gel electrophoresis method to quantify protein differences among forebrain extracts prepared from ground squirrels in two summer, four winter and fall transition states. Proteins that differed among groups were identified using LC-MS/MS. Only 84 protein spots varied significantly among the defined states of hibernation. Protein changes in the forebrain proteome fell largely into two reciprocal patterns with a strong body temperature dependence. The importance of body temperature was tested in animals from the fall; these fall animals use torpor sporadically with body temperatures mirroring ambient temperatures between 4 and 21°C as they navigate the transition between summer homeothermy and winter heterothermy. Unlike cold-torpid fall ground squirrels, warm-torpid individuals strongly resembled the homeotherms, indicating that the changes observed in torpid hibernators are defined by body temperature, not torpor per se. Metabolic enzymes were largely unchanged despite varied metabolic activity across annual and torpor-arousal cycles. Instead, the majority of the observed changes were cytoskeletal proteins and their regulators. While cytoskeletal structural proteins tended to differ seasonally, i.e., between summer homeothermy and winter heterothermy, their regulatory proteins were more strongly affected by body temperature. Changes in the abundance of various isoforms of the microtubule assembly and disassembly regulatory proteins dihydropyrimidinase

  9. Comparison of surface temperature in 13-lined ground squirrel (Spermophilus tridecimlineatus) and yellow-bellied marmot (Marmota flaviventris) during arousal from hibernation.

    PubMed

    Phillips, P K; Heath, J E

    2004-08-01

    Surface temperatures (Ts) of eight 13-lined ground squirrels and seven yellow-bellied marmots were measured during arousal from hibernation using infrared thermography (IRT) and recorded on videotape. Animals aroused normally in 5 degrees C cold rooms. Body temperatures were recorded during arousal using both cheek pouch and interscapular temperature probes. Warming rate in arousal was exponential. Mean mass specific warming rates show the squirrels warm faster (69.76 degrees C/h/kg) than the marmots (4.49 degrees C/h/kg). Surface temperatures (Ts) for 11 regions were measured every few minutes during arousal. The smaller ground squirrel shows the ability to perfuse distal regions without compromising rise in deep body temperature (Tb). All squirrel Ts's remained low as Tb rose to 18 degrees C, at which point, eyes opened, squirrels became more active and all Ts's rose parallel to Tb. Marmot Ts remained low as Tb rose initially. Each marmot showed a plateau phase where Tb remained constant (mean Tb 20.3+/-1.0 degrees C, duration 9.4+/-4.1 min) during which time all Ts's rose, and then remained relatively constant as Tb again began to rise. An anterior to posterior Ts gradient was evident in the ground squirrel, both body and feet. This gradient was only evident in the feet of the marmots.

  10. Metabolic changes associated with the long winter fast dominate the liver proteome in 13-lined ground squirrels.

    PubMed

    Hindle, Allyson G; Grabek, Katharine R; Epperson, L Elaine; Karimpour-Fard, Anis; Martin, Sandra L

    2014-05-15

    Small-bodied hibernators partition the year between active homeothermy and hibernating heterothermy accompanied by fasting. To define molecular events underlying hibernation that are both dependent and independent of fasting, we analyzed the liver proteome among two active and four hibernation states in 13-lined ground squirrels. We also examined fall animals transitioning between fed homeothermy and fasting heterothermy. Significantly enriched pathways differing between activity and hibernation were biased toward metabolic enzymes, concordant with the fuel shifts accompanying fasting physiology. Although metabolic reprogramming to support fasting dominated these data, arousing (rewarming) animals had the most distinct proteome among the hibernation states. Instead of a dominant metabolic enzyme signature, torpor-arousal cycles featured differences in plasma proteins and intracellular membrane traffic and its regulation. Phosphorylated NSFL1C, a membrane regulator, exhibited this torpor-arousal cycle pattern; its role in autophagosome formation may promote utilization of local substrates upon metabolic reactivation in arousal. Fall animals transitioning to hibernation lagged in their proteomic adjustment, indicating that the liver is more responsive than preparatory to the metabolic reprogramming of hibernation. Specifically, torpor use had little impact on the fall liver proteome, consistent with a dominant role of nutritional status. In contrast to our prediction of reprogramming the transition between activity and hibernation by gene expression and then within-hibernation transitions by posttranslational modification (PTM), we found extremely limited evidence of reversible PTMs within torpor-arousal cycles. Rather, acetylation contributed to seasonal differences, being highest in winter (specifically in torpor), consistent with fasting physiology and decreased abundance of the mitochondrial deacetylase, SIRT3.

  11. Intracellular antioxidant enzymes are not globally upregulated during hibernation in the major oxidative tissues of the 13-lined ground squirrel Spermophilus tridecemlineatus.

    PubMed

    Page, Melissa M; Peters, Craig W; Staples, James F; Stuart, Jeffrey A

    2009-01-01

    Hibernating mammals exhibit oxidative stress resistance in brain, liver and other tissues. In many animals, cellular oxidative stress resistance is associated with enhanced expression of intracellular antioxidant enzymes. Intracellular antioxidant capacity may be upregulated during hibernation to protect against oxidative damage associated with the ischemia-reperfusion that occurs during transitions between torpor and arousal. We tested the hypothesis that the 13-lined ground squirrel (Spermophilus tridecemlineatus), upregulates intracellular antioxidant enzymes in major oxidative tissues during hibernation. The two major intracellular isoforms of superoxide dismutase (MnSOD and CuZnSOD), which catalyze the first step in superoxide detoxification, were quantified in heart, brain and liver tissue using immunodetection and an in-gel activity assay. However, no differences in SOD protein expression or activity were found between active and hibernating squirrels. Measurements of glutathione peroxidase and glutathione reductase, which catalyze hydrogen peroxide removal, were not broadly upregulated during hibernation. The activity of catalase, which catalyzes an alternative hydrogen peroxide detoxification pathway, was higher in heart and brain of torpid squirrels, but lower in liver. Taken together, these data do not support the hypothesis that hibernation is associated with enhanced oxidative stress resistance due to an upregulation of intracellular antioxidant enzymes in the major oxidative tissues.

  12. Hibernation is associated with depression of T-cell independent humoral immune responses in the 13-lined ground squirrel.

    PubMed

    Bouma, Hjalmar R; Henning, Robert H; Kroese, Frans G M; Carey, Hannah V

    2013-03-01

    Mammalian hibernation consists of periods of low metabolism and body temperature (torpor), interspersed by euthermic arousal periods. The function of both the innate and adaptive immune system is suppressed during hibernation. In this study, we analyzed the humoral adaptive immune response to a T-cell independent (TI-2) and a T-cell dependent (TD) antigen. Thirteen-lined ground squirrels were immunized in summer or during hibernation with either a TI-2 or TD antigen on day 0 and day 14. Blood was drawn on day 0, 7, 14, 21 and 28. Both types of antigens induced a significant rise in antibody titer in summer animals. Much to our surprise, however, only immunization with the TD antigen, and not with the TI-2 antigen induced a humoral response in hibernators. Flow cytometric analysis of CD4 (helper T-lymphocytes), CD8 (cytotoxic T-lymphocytes) and CD45RA (B-lymphocytes) in blood, spleen and lymph nodes ruled out massive apoptosis as explanation of the absent TI humoral response during hibernation. Rather, reduced TI-2 stimulation of B-lymphocytes, possibly due to lowered serum complement during torpor, may explain the reduced antibody production in response to a TI-2 antigen. These results demonstrate that hibernation diminishes the capacity to induce a TI-2 humoral immune response, while the capacity to induce a humoral response to a TD antigen is maintained.

  13. Tissue-specific response of carbohydrate-responsive element binding protein (ChREBP) to mammalian hibernation in 13-lined ground squirrels.

    PubMed

    Logan, Samantha M; Storey, Kenneth B

    2016-10-01

    Mammalian hibernation is characterized by a general suppression of energy expensive processes and a switch to lipid oxidation as the primary fuel source. Glucose-responsive carbohydrate responsive element binding protein (ChREBP) has yet to be studied in hibernating organisms, which prepare for the cold winter months by feeding until they exhibit an obesity-like state that is accompanied by naturally-induced and completely reversible insulin resistance. Studying ChREBP expression and activity in the hibernating 13-lined ground squirrel is important to better understand the molecular mechanisms that regulate energy metabolism under cellular stress. Immunoblotting was used to determine the relative expression level and subcellular localization of ChREBP, as well as serine phosphorylation at 95 kDa, comparing euthermic and late torpid ground squirrel liver, kidney, heart and muscle. DNA-binding ELISAs and RT-PCR were used to explore ChREBP transcriptional activity during cold stress. ChREBP activity seemed generally suppressed in liver and kidney. During torpor, ChREBP total protein levels decreased to 44% of EC in liver, phosphoserine levels increased 2.1-fold of EC in kidney, and downstream Fasn/Pkl transcript levels decreased to <60% of EC in liver. By contrast, ChREBP activity generally increased during torpor in cardiac and skeletal muscle, where ChREBP total protein levels increased over 1.5-fold and 5-fold of EC in muscle and heart, respectively; where DNA-binding increased by ∼2-fold of EC in muscle; and where Fasn transcript levels increased over 3-fold and 7-fold in both muscle and heart, respectively. In summary, ChREBP has a tissue-specific role in regulating energy metabolism during hibernation.

  14. Analysis of microRNA expression during the torpor-arousal cycle of a mammalian hibernator, the 13-lined ground squirrel.

    PubMed

    Wu, Cheng-Wei; Biggar, Kyle K; Luu, Bryan E; Szereszewski, Kama E; Storey, Kenneth B

    2016-06-01

    Hibernation is a highly regulated stress response that is utilized by some mammals to survive harsh winter conditions and involves a complex metabolic reprogramming at the cellular level to maintain tissue protections at low temperature. In this study, we profiled the expression of 117 conserved microRNAs in the heart, muscle, and liver of the 13-lined ground squirrel (Ictidomys tridecemlineatus) across four stages of the torpor-arousal cycle (euthermia, early torpor, late torpor, and interbout arousal) by real-time PCR. We found significant differential regulation of numerous microRNAs that were both tissue specific and torpor stage specific. Among the most significant regulated microRNAs was miR-208b, a positive regulator of muscle development that was found to be upregulated by fivefold in the heart during late torpor (13-fold during arousal), while decreased by 3.7-fold in the skeletal muscle, implicating a potential regulatory role in the development of cardiac hypertrophy and skeletal muscle atrophy in the ground squirrels during torpor. In addition, the insulin resistance marker miR-181a was upregulated by 5.7-fold in the liver during early torpor, which supports previous suggestions of hyperinsulinemia in hibernators during the early stages of the hibernation cycle. Although microRNA expression profiles were largely unique between the three tissues, GO annotation analysis revealed that the putative targets of upregulated microRNAs tend to enrich toward suppression of progrowth-related processes in all three tissues. These findings implicate microRNAs in the regulation of both tissue-specific processes and general suppression of cell growth during hibernation.

  15. Hibernation alters the diversity and composition of mucosa-associated bacteria while enhancing antimicrobial defence in the gut of 13-lined ground squirrels.

    PubMed

    Dill-McFarland, Kimberly A; Neil, Katie L; Zeng, Austin; Sprenger, Ryan J; Kurtz, Courtney C; Suen, Garret; Carey, Hannah V

    2014-09-01

    The gut microbiota plays important roles in animal nutrition and health. This relationship is particularly dynamic in hibernating mammals where fasting drives the gut community to rely on host-derived nutrients instead of exogenous substrates. We used 16S rRNA pyrosequencing and caecal tissue protein analysis to investigate the effects of hibernation on the mucosa-associated bacterial microbiota and host responses in 13-lined ground squirrels. The mucosal microbiota was less diverse in winter hibernators than in actively feeding spring and summer squirrels. UniFrac analysis revealed distinct summer and late winter microbiota clusters, while spring and early winter clusters overlapped slightly, consistent with their transitional structures. Communities in all seasons were dominated by Firmicutes and Bacteroidetes, with lesser contributions from Proteobacteria, Verrucomicrobia, Tenericutes and Actinobacteria. Hibernators had lower relative abundances of Firmicutes, which include genera that prefer plant polysaccharides, and higher abundances of Bacteroidetes and Verrucomicrobia, some of which can survive solely on host-derived mucins. A core mucosal assemblage of nine operational taxonomic units shared among all individuals was identified with an average total sequence abundance of 60.2%. This core community, together with moderate shifts in specific taxa, indicates that the mucosal microbiota remains relatively stable over the annual cycle yet responds to substrate changes while potentially serving as a pool for 'seeding' the microbiota once exogenous substrates return in spring. Relative to summer, hibernation reduced caecal crypt length and increased MUC2 expression in early winter and spring. Hibernation also decreased caecal TLR4 and increased TLR5 expression, suggesting a protective response that minimizes inflammation.

  16. North American tree squirrels and ground squirrels with overlapping ranges host different Cryptosporidium species and genotypes.

    PubMed

    Stenger, Brianna L S; Clark, Mark E; Kváč, Martin; Khan, Eakalak; Giddings, Catherine W; Prediger, Jitka; McEvoy, John M

    2015-12-01

    Wildlife-associated Cryptosporidium are an emerging cause of cryptosporidiosis in humans. The present study was undertaken to determine the extent to which North American tree squirrels and ground squirrels host zoonotic Cryptosporidium species and genotypes. Fragments of the Cryptosporidium 18S rRNA and actin genes were amplified and sequenced from fecal samples obtained from three tree squirrel and three ground squirrel species. In tree squirrels, Cryptosporidium was identified in 40.5% (17/42) of American red squirrels (Tamiasciurus hudsonicus), 40.4% (55/136) of eastern gray squirrels (Sciurus carolinensis), and 28.6% (2/7) of fox squirrels (Sciurus niger). Human-pathogenic Cryptosporidium ubiquitum and Cryptosporidium skunk genotype were the most prevalent species/genotypes in tree squirrels. Because tree squirrels live in close proximity to humans and are frequently infected with potentially zoonotic Cryptosporidium species/genotypes, they may be a significant reservoir of infection in humans. In ground squirrels, Cryptosporidium was detected in 70.2% (33/47) of 13-lined ground squirrels (Ictidomys tridecemlineatus), 35.1% (27/77) of black-tailed prairie dogs (Cynomys ludovicianus), and the only golden-mantled ground squirrel (Callospermophilus lateralis) that was sampled. Cryptosporidium rubeyi and ground squirrel genotypes I, II, and III were identified in isolates from these ground squirrel species. In contrast to the Cryptosporidium infecting tree squirrels, these species/genotypes appear to be specific for ground squirrels and are not associated with human disease.

  17. Noninvasive imaging of the thirteen-lined ground squirrel photoreceptor mosaic

    PubMed Central

    Sajdak, Benjamin; Sulai, Yusufu N.; Langlo, Christopher S.; Luna, Gabriel; Fisher, Steven K.; Merriman, Dana K.; Dubra, Alfredo

    2016-01-01

    Ground squirrels are an increasingly important model for studying visual processing, retinal circuitry, and cone photoreceptor function. Here, we demonstrate that the photoreceptor mosaic can be longitudinally imaged noninvasively in the 13-lined ground squirrel (Ictidomys tridecemlineatus) using confocal and nonconfocal split-detection adaptive optics scanning ophthalmoscopy using 790 nm light. Photoreceptor density, spacing, and Voronoi analysis are consistent with that of the human cone mosaic. The high imaging success rate and consistent image quality in this study reinforce the ground squirrel as a practical model to aid drug discovery and testing through longitudinal imaging on the cellular scale. PMID:26923645

  18. Noninvasive imaging of the thirteen-lined ground squirrel photoreceptor mosaic.

    PubMed

    Sajdak, Benjamin; Sulai, Yusufu N; Langlo, Christopher S; Luna, Gabriel; Fisher, Steven K; Merriman, Dana K; Dubra, Alfredo

    2016-01-01

    Ground squirrels are an increasingly important model for studying visual processing, retinal circuitry, and cone photoreceptor function. Here, we demonstrate that the photoreceptor mosaic can be longitudinally imaged noninvasively in the 13-lined ground squirrel (Ictidomys tridecemlineatus) using confocal and nonconfocal split-detection adaptive optics scanning ophthalmoscopy using 790 nm light. Photoreceptor density, spacing, and Voronoi analysis are consistent with that of the human cone mosaic. The high imaging success rate and consistent image quality in this study reinforce the ground squirrel as a practical model to aid drug discovery and testing through longitudinal imaging on the cellular scale.

  19. Contrasting stress response of male arctic ground squirrels and red squirrels.

    PubMed

    Boonstra, R; McColl, C J

    2000-03-01

    A hormonal-challenge protocol was used to compare the stress response of males of Arctic ground squirrels and red squirrels during the breeding season (May). These squirrels live in the same boreal forest of the Yukon, but have very different life histories and utilize the forest in markedly different ways. Red squirrels had levels of total cortisol, maximum corticosteroid-binding capacity, and free cortisol that were 5, 7, and 2 times, respectively, those of Arctic ground squirrels. Red squirrels were resistant to suppression by an artificial glucocorticoid, dexamethasone (DEX); Arctic ground squirrels were not. Cortisol levels in red squirrels responded slowly but continuously to the ACTH injection; Arctic ground squirrels responded rapidly and then stabilized. Testosterone levels in red squirrels were extremely sensitive to the challenge, being suppressed by both DEX and ACTH; levels in Arctic ground squirrels were resistant to the challenge, being modestly suppressed by DEX and stimulated by ACTH. Energy mobilization, as measured by glucose and free fatty acid responses, was not affected. Red squirrels had four times the levels of white blood cells and higher proportions of lymphocytes and lower proportions of eosinophils than Arctic ground squirrels, indicating that the latter were in worse condition immunologically. Our evidence suggests that the functions associated with the hypothalamic-pituitary-adrenal axis are compromised in breeding male Arctic ground squirrels, but not in red squirrels. We propose that in male red squirrels this axis has evolved in the context of a stable social system based on long-lived animals with individual territories which are needed to deal with unpredictable winter food supplies. In contrast, Arctic ground squirrels escape the rigors of winter by hibernation and this hormonal axis has evolved in short-lived males in the context of intense intra-sexual competition in a social system based on female kin groups and regular male

  20. Eye model for the ground squirrel

    NASA Astrophysics Data System (ADS)

    Sussman, Dafna; Chou, B. Ralph; Lakshminarayanan, Vasudevan

    2011-11-01

    This paper presents an anatomically-correct eye model for the ground squirrel, a diurnal, highly-developed mammal with high visual acuity. This model can assist in understanding the relationship between ocular structural development and its corresponding function. The eye model is constructed based on anatomical measurements of thicknesses and indices of refraction of the various ocular media. The model then derives the gradient index distribution of the crystalline lens using a ray tracing method with a Monte Carlo optimization. Results indicate a diffraction-limited ocular behaviour, implying the visual acuity of the ground squirrel is more likely to be limited by photoreceptor density and diffraction effects, than by ocular geometry.

  1. Gangrenous dermatitis caused by Corynebacterium ulcerans in Richardson ground squirrels.

    PubMed

    Olson, M E; Goemans, I; Bolingbroke, D; Lundberg, S

    1988-08-01

    Gangrenous dermatitis caused by Corynebacterium ulcerans developed in 63 of 350 wild Richardson ground squirrels (Spermophilus richardsonii). Six squirrels died of toxemia and/or septicemia, but 57 responded to topical and parenteral administration of antibiotics. The epizo-otic was believed to be associated with fighting; infected and carrier ground squirrels most likely transmitted the C ulcerans through bite wounds. Individuals handling ground squirrels should be cautioned that C ulcerans may produce a diphtheria-like disease in human beings.

  2. Arctic Ground Squirrels Limit Bone Loss during the Prolonged Physical Inactivity Associated with Hibernation.

    PubMed

    Wojda, Samantha J; Gridley, Richard A; McGee-Lawrence, Meghan E; Drummer, Thomas D; Hess, Ann; Kohl, Franziska; Barnes, Brian M; Donahue, Seth W

    2016-01-01

    Prolonged disuse (e.g., physical inactivity) typically results in increased bone porosity, decreased mineral density, and decreased bone strength, leading to increased fracture risk in many mammals. However, bears, marmots, and two species of ground squirrels have been shown to preserve macrostructural bone properties and bone strength during long seasons of hibernation while they remain mostly inactive. Some small hibernators (e.g., 13-lined ground squirrels) show microstructural bone loss (i.e., osteocytic osteolysis) during hibernation, which is not seen in larger hibernators (e.g., bears and marmots). Arctic ground squirrels (Urocitellus parryii) are intermediate in size between 13-lined ground squirrels and marmots and are perhaps the most extreme rodent hibernator, hibernating for up to 8 mo annually with body temperatures below freezing. The goal of this study was to quantify the effects of hibernation and inactivity on cortical and trabecular bone properties in arctic ground squirrels. Cortical bone geometrical properties (i.e., thickness, cross-sectional area, and moment of inertia) at the midshaft of the femur were not different in animals sampled over the hibernation and active seasons. Femoral ultimate stress tended to be lower in hibernators than in summer animals, but toughness was not affected by hibernation. The area of osteocyte lacunae was not different between active and hibernating animals. There was an increase in osteocytic lacunar porosity in the hibernation group due to increased lacunar density. Trabecular bone volume fraction in the proximal tibia was unexpectedly greater in the hibernation group than in the active group. This study shows that, similar to other hibernators, arctic ground squirrels are able to preserve many bone properties during hibernation despite being physically inactive for up to 8 mo.

  3. UV filters in the lens of the thirteen lined ground squirrel (Spermophilus tridecemlineatus).

    PubMed

    Hains, P G; Simpanya, M F; Giblin, F; Truscott, R J W

    2006-04-01

    Major UV filters have been identified in the lens of the 13 lined ground squirrel (Spermophilus tridecemlineatus). These were found to be N-acetyl-3-hydroxykynurenine and N-acetyl-kynurenine, in addition to a small quantity of 3-hydroxykynurenine. The level of N-acetyl-3-hydroxykynurenine measured in the ground squirrel lens, 8.2mM, is approximately 11 times the concentration of 3-hyroxykynurenine glucoside reported previously for the human lens. Two additional UV filters of related structure were also present; however, their structures are still under investigation. HPLC elution profiles indicated that the ground squirrel lens cortex and nucleus contained comparable amounts of alpha-, beta(H)-, beta(L)-, and gamma-crystallins. Levels of GSH in the cortex and nucleus were 12.4 and 7.4mM, respectively. Such high concentrations of GSH may act to inhibit oxidation of the 3-hydroxykynurenine and N-acetyl-3-hydroxykynurenine. N-Acetylated kynurenines are less labile than those with free alpha-amino groups since N-acetyl-alpha-amino groups do not undergo spontaneous deamination. This modification thus stabilises the squirrel UV filters. In addition, because deamination is prevented, the decomposition products will not be involved in binding to lens proteins. Because of the similarity of the UV filters present in the ground squirrel to those in man, this species may be a suitable animal model for investigating the effects of UV radiation on cataract, and other ocular diseases, thought to involve exposure to light.

  4. Bipolar cells of the ground squirrel retina.

    PubMed

    Puller, Christian; Ondreka, Katharina; Haverkamp, Silke

    2011-03-01

    Parallel processing of an image projected onto the retina starts at the first synapse, the cone pedicle, and each cone feeds its light signal into a minimum of eight different bipolar cell types. Hence, the morphological classification of bipolar cells is a prerequisite for analyzing retinal circuitry. Here we applied common bipolar cell markers to the cone-dominated ground squirrel retina, studied the labeling by confocal microscopy and electron microscopy, and compared the resulting bipolar cell types with those of the mouse (rod dominated) and primate retina. Eight different cone bipolar cell types (three OFF and five ON) and one rod bipolar cell were distinguished. The major criteria for classifying the cells were their immunocytochemical identity, their dendritic branching pattern, and the shape and stratification level of their axons in the inner plexiform layer (IPL). Immunostaining with antibodies against Gγ13, a marker for ON bipolar cells, made it possible to separate OFF and ON bipolars. Recoverin-positive OFF bipolar cells partly overlapped with ON bipolar axon terminals at the ON/OFF border of the IPL. Antibodies against HCN4 labeled the S-cone selective (bb) bipolar cell. The calcium-binding protein CaB5 was expressed in two OFF and two ON cone bipolar cell types, and CD15 labeled a widefield ON cone bipolar cell comparable to the DB6 in primate.

  5. Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) show microstructural bone loss during hibernation but preserve bone macrostructural geometry and strength.

    PubMed

    McGee-Lawrence, Meghan E; Stoll, Danielle M; Mantila, Emily R; Fahrner, Bryna K; Carey, Hannah V; Donahue, Seth W

    2011-04-15

    Lack of activity causes bone loss In most animals. Hibernating bears have physiological processes to prevent cortical and trabecular bone loss associated with reduced physical activity, but different mechanisms of torpor among hibernating species may lead to differences in skeletal responses to hibernation. There are conflicting reports regarding whether small mammals experience bone loss during hibernation. To investigate this phenomenon, we measured cortical and trabecular bone properties in physically active and hibernating juvenile and adult 13-lined ground squirrels (Ictidomys tridecemlineatus, previous genus name Spermophilus). Cortical bone geometry, strength and mineral content were similar in hibernating compared with active squirrels, suggesting that hibernation did not cause macrostructural cortical bone loss. Osteocyte lacunar size increased (linear regression, P=0.001) over the course of hibernation in juvenile squirrels, which may indicate an osteocytic role in mineral homeostasis during hibernation. Osteocyte lacunar density and porosity were greater (+44 and +59%, respectively; P<0.0001) in hibernating compared with active squirrels, which may reflect a decrease in osteoblastic activity (per cell) during hibernation. Trabecular bone volume fraction in the proximal tibia was decreased (-20%; P=0.028) in hibernating compared with physically active adult squirrels, but was not different between hibernating and active juvenile squirrels. Taken together, these data suggest that 13-lined ground squirrels may be unable to prevent microstructural losses of cortical and trabecular bone during hibernation, but importantly may possess a biological mechanism to preserve cortical bone macrostructure and strength during hibernation, thus preventing an increased risk of bone fracture during remobilization in the spring.

  6. Simple and integrated detours: field tests with Columbian ground squirrels.

    PubMed

    Nesterova, Anna Pavlovna; Hansen, Frank

    2009-09-01

    An internal representation of space offers flexibility to animals during orientation and allows execution of short cuts and detours. We tested the ability of 19 free-ranging Columbian ground squirrels (Spermophilus columbianus) to perform integrated detours that required travelling under- and aboveground. Squirrels were individually tested on their territories (2 tests) and in an arena (7 tests). During tests, animals could reach food by running aboveground and then through tunnels. For the territory tests, natural tunnels were available. For the arena tests, animals used artificial tunnels within a fenced-in part of the meadow. For the last arena test, tubes were placed aboveground replicating the underground structure. In this test animals were asked to make a simple detour, when the full path to the goal was visible. On their territories, 41% of squirrels performed detours. All animals reached the food in the arena. When choosing an arena detour, squirrels based their decision on the proximity of the burrow as well as on whether it led to food. On the last arena test, more squirrels performed correct detours on the first attempt compared to other tests. The results suggest that ground squirrels can perform simple and integrated detours, but animals perform better if the full path is visible.

  7. A new hepadnavirus endemic in arctic ground squirrels in Alaska.

    PubMed

    Testut, P; Renard, C A; Terradillos, O; Vitvitski-Trepo, L; Tekaia, F; Degott, C; Blake, J; Boyer, B; Buendia, M A

    1996-07-01

    We present evidence for a novel member of the hepadnavirus family that is endemic in wild arctic ground squirrels (Spermophylus parryi kennicotti) in Alaska. This virus, designated arctic squirrel hepatitis virus (ASHV), was initially detected in the livers of animals bearing large hepatic nodules by nucleic acid hybridization with hepadnavirus probes and in plasma by cross-reactivity with antibodies to hepadnavirus surface and core antigens. The complete nucleotide sequence of the 3,302-bp-long ASHV genome was determined and compared with those of ground squirrel hepatitis virus (GSHV) and woodchuck hepatitis virus (WHV); all sequences were organized into four open reading frames, designated pre-C/C, pre-S/S, pol, and X. Despite roughly equivalent variability among the three rodent hepadnaviruses (around 16% base and 19% amino acid exchanges), ASHV appeared to be more closely related to GSHV than to WHV in phylogenetic analysis. Accordingly, preliminary studies of the pathology of ASHV infection suggested that ASHV may be a less efficient oncogenic agent than WHV. About one-third of aged animals maintained in captivity, including virus-infected as well as uninfected squirrels, developed large liver nodules, consisting of hepatocellular adenomas or carcinomas or nonmalignant lesions characterized by drastic microvesicular steatosis. ASHV-infected arctic ground squirrels may serve as a new model with which to analyze the contribution of hepadnavirus- and host-specific determinants to liver pathology and tumorigenesis.

  8. A new hepadnavirus endemic in arctic ground squirrels in Alaska.

    PubMed Central

    Testut, P; Renard, C A; Terradillos, O; Vitvitski-Trepo, L; Tekaia, F; Degott, C; Blake, J; Boyer, B; Buendia, M A

    1996-01-01

    We present evidence for a novel member of the hepadnavirus family that is endemic in wild arctic ground squirrels (Spermophylus parryi kennicotti) in Alaska. This virus, designated arctic squirrel hepatitis virus (ASHV), was initially detected in the livers of animals bearing large hepatic nodules by nucleic acid hybridization with hepadnavirus probes and in plasma by cross-reactivity with antibodies to hepadnavirus surface and core antigens. The complete nucleotide sequence of the 3,302-bp-long ASHV genome was determined and compared with those of ground squirrel hepatitis virus (GSHV) and woodchuck hepatitis virus (WHV); all sequences were organized into four open reading frames, designated pre-C/C, pre-S/S, pol, and X. Despite roughly equivalent variability among the three rodent hepadnaviruses (around 16% base and 19% amino acid exchanges), ASHV appeared to be more closely related to GSHV than to WHV in phylogenetic analysis. Accordingly, preliminary studies of the pathology of ASHV infection suggested that ASHV may be a less efficient oncogenic agent than WHV. About one-third of aged animals maintained in captivity, including virus-infected as well as uninfected squirrels, developed large liver nodules, consisting of hepatocellular adenomas or carcinomas or nonmalignant lesions characterized by drastic microvesicular steatosis. ASHV-infected arctic ground squirrels may serve as a new model with which to analyze the contribution of hepadnavirus- and host-specific determinants to liver pathology and tumorigenesis. PMID:8676441

  9. Hepatic capillariasis in a Cape ground squirrel (Xerus inaurus).

    PubMed

    Erlwanger, K H; De Witt, B A; Fick, L G; Hetem, R S; Meyer, L C R; Mitchell, D; Wilson, W A; Mitchell, B

    2009-12-01

    We report, for the first time, an incidental finding of Calodium hepaticum infestation in a sub-adult female Cape ground squirrel (Xerus inaurus). Post mortem examination of the squirrel revealed severe haemoperitoneum, splenomegaly and hepatomegaly with miliary white spots distributed diffusely throughout the hepatic parenchyma. Histologically the portal tracts in the liver showed granulomatous inflammation with fibrosis and numerous giant cells. Occasional adult worms were identified and there were multiple C. hepaticum eggs distributed diffusely throughout the portal tracts and the parenchyma. The spleen also contained C. hepaticum eggs. The genus Rattus is the primary host and reservoir of C. hepaticum, but C. hepaticum infections have been reported previously in other Sciuridae. Based on our findings, people should be cautious of the zoonotic potential of C. hepaticum, when they come into contact with the Cape ground squirrel.

  10. Fatty acids and cholesterol in the liver cell nuclei of hibernating Yakutian ground squirrels.

    PubMed

    Kolomiytseva, I K; Lakhina, A A; Markevich, L N; Fesenko, E E

    2016-09-01

    The content of neutral lipids in tissue homogenates and liver cell nuclei of hibernating Yakutian ground squirrels was studied. In homogenates, hibernation increases the content of fatty acids and reduces the content of glycerides and cholesterol. When studying the liver cell nuclei of torpid winter ground squirrels, we detected a twofold increase in the content of fatty acids, cholesterol, and monoglycerides as compared to the "summer" ground squirrels. In the active "winter" ground squirrels, as compared to the torpid winter ones, the content of cholesterol did not change, whereas the content of fatty acids, monoglycerides, and diglycerides decreased but remained higher than in the "summer" ground squirrels.

  11. Karyotypic evolution of the family Sciuridae: inferences from the genome organizations of ground squirrels.

    PubMed

    Li, T; Wang, J; Su, W; Nie, W; Yang, F

    2006-01-01

    Cross-species chromosome painting has made a great contribution to our understanding of the evolution of karyotypes and genome organizations of mammals. Several recent papers of comparative painting between tree and flying squirrels have shed some light on the evolution of the family Sciuridae and the order Rodentia. In the present study we have extended the comparative painting to the Himalayan marmot (Marmotahimalayana) and the African ground squirrel (Xerus cf. erythropus), i.e. representative species from another important squirrel group--the ground squirrels--, and have established genome-wide comparative chromosome maps between human, eastern gray squirrel, and these two ground squirrels. The results show that 1) the squirrels so far studied all have conserved karyotypes that resemble the ancestral karyotype of the order Rodentia; 2) the African ground squirrels could have retained the ancestral karyotype of the family Sciuridae. Furthermore, we have mapped the evolutionary rearrangements onto a molecular-based consensus phylogenetic tree of the family Sciuridae.

  12. Bullet fragments in Belding's ground squirrels in Oregon and California in 2014-2015

    USGS Publications Warehouse

    Herring, Garth; Eagles-Smith, Collin A.

    2016-01-01

    The dataset includes specifics on fragments of bullets recovered from shot Belding's ground squirrels from Oregon and California. Ground squirrels were radiographed and then we used ImageJ software to count and measure the area of those bullet fragments. A subset of shot carcasses were then digested and bullet fragments were recovered. Statistical models were developed to predict either the number or mass of bullet fragments in shot ground squirrel carcasses using the radiograph estimates and the digested recovered fragment data.

  13. Populations and habitat relationships of Piute ground squirrels in southwest Idaho

    USGS Publications Warehouse

    Steenhof, Karen; Yensen, Eric; Kochert, Michael N.; Gage, K.

    2006-01-01

    Piute ground squirrels (Spermophilus mollis idahoensis) are normally above ground from late January until late June or early July in the Snake River Birds of Prey National Conservation Area in southwestern Idaho. In 2002 they were rarely seen above ground after early May. Because of the ecological importance of ground squirrels for nesting raptors and other species, we sought to determine the reasons for their early disappearance. We sampled 12 sites from January 2003 through March 2003 to determine if a population crash had occurred in 2002. Tests indicated that Piute ground squirrels had not been exposed to plague within the past year. The presence of yearlings in the population indicated that squirrels reproduced in 2002 and that at least some yearlings survived the winter. Both yearling and adult squirrels appeared to be reproducing at or above normal rates in 2003. The most plausible explanation for the early disappearance of Piute ground squirrels in 2002 is that squirrels entered seasonal torpor early in response to a late spring drought. In addition, the breeding chronology of squirrels may have shifted during the past 2 decades in response to climate change and/or habitat alteration. Shrub habitats provide a more favorable and stable environment for squirrels than grass habitats. Squirrel abundance was higher on live-trapping grids with sagebrush than on grids dominated by grass, and squirrel masses were higher at sites dominated by shrubs and Sandberg bluegrass (Poa secunda). Densities in big sagebrush (Artemisia tridentata) were within the ranges reported for earlier years, but densities in grass were lower than previously reported. Low densities at grassland sites in 2003 support other findings that drought affects squirrels in altered grass communities more than those in native shrub habitats. Long-term shifts in ground squirrel breeding chronology may have implications for raptors that depend on them for food.

  14. Social conditioned place preference in the captive ground squirrel (Ictidomys tridecemlineatus): Social reward as a natural phenotype.

    PubMed

    Lahvis, Garet P; Panksepp, Jules B; Kennedy, Bruce C; Wilson, Clarinda R; Merriman, Dana K

    2015-08-01

    Social behaviors of wild animals are often considered within an ultimate framework of adaptive benefits versus survival risks. By contrast, studies of laboratory animals more typically focus on affective aspects of behavioral decisions, whether a rodent derives a rewarding experience from social encounter, and how this experience might be initiated and maintained by neural circuits. Artificial selection and inbreeding have rendered laboratory animals more affiliative and less aggressive than their wild conspecifics, leaving open the possibility that social reward is an artifact of domestication. We compared social behaviors of wild and captive population of juvenile 13-lined ground squirrels (Ictidomys tridecemlineatus), the latter being 2nd- and 3rd-generation descendants of wild individuals. At an age corresponding to emergence from the burrow, postnatal day (PD) 38, captive squirrels engaged in vigorous social approach and play and these juvenile behaviors declined significantly by PD 56. Similarly, young wild squirrels expressed social proximity and play; affiliative interactions declined with summer's progression and were replaced by agonistic chasing behaviors. Social conditioned place preference testing (conditioned PDs 40-50) indicated that adolescent squirrels derived a rewarding experience from social reunion. Our results support the contention that undomesticated rodents have the capacity for social reward and more generally suggest the possibility that positive affective experiences may support group cohesion, social cooperation, and altruism in the wild.

  15. Regulation of Akt during torpor in the hibernating ground squirrel, Ictidomys tridecemlineatus.

    PubMed

    McMullen, David C; Hallenbeck, John M

    2010-08-01

    The 13-lined ground squirrel (Ictidomys tridecemlineatus) is capable of entering into extended periods of torpor during winter hibernation. The state of torpor represents a hypometabolic shift wherein the rate of oxygen consuming processes are strongly repressed in an effort to maintain cellular homeostasis as the availability of food energy becomes limited. We are interested in studying hibernation/torpor because of the robust state of tolerance to constrained oxygen delivery, oligemia, and hypothermia achieved by the tissues of hibernating mammals. The role of the serine/threonine kinase Akt (also known as PKB) has been examined in torpor in previous studies. However, this is the first study that examines the level of Akt phosphorylation in the liver during the two transition phases of the hibernation cycle: entrance into torpor, and the subsequent arousal from torpor. Our results indicate that Akt is activated in the squirrel liver by phosphorylation of two key residues (Thr(308) and Ser(473)) during entrance into torpor and arousal from torpor. Moreover, we observed increased phosphorylation of key substrates of Akt during the two transition stages of torpor. Finally, this study reports the novel finding that PRAS40, a component of the TORC1 multi-protein complex and a potentially important modulator of metabolism, is regulated during torpor.

  16. Fitness implications of seasonal climate variation in Columbian ground squirrels.

    PubMed

    Dobson, F Stephen; Lane, Jeffrey E; Low, Matthew; Murie, Jan O

    2016-08-01

    The influence of climate change on the fitness of wild populations is often studied in the context of the spring onset of the reproductive season. This focus is relevant for climate influences on reproductive success, but neglects other fitness-relevant periods (e.g., autumn preparation for overwintering). We examined variation in climate variables (temperature, rainfall, snowfall, and snowpack) across the full annual cycle of Columbian ground squirrels (Urocitellus columbianus) for 21 years. We investigated seasonal climate variables that were associated with fitness variables, climate variables that exhibited directional changes across the study period, and finally observed declines in fitness (-0.03 units/year; total decline = 37%) that were associated with directional changes in climate variables. Annual fitness of adult female ground squirrels was positively associated with spring temperature (r = 0.69) and early summer rainfall (r = 0.56) and negatively associated with spring snow conditions (r = -0.44 to -0.66). Across the 21 years, spring snowmelt has become significantly delayed (r = 0.48) and summer rainfall became significantly reduced (r = -0.53). Using a standardized partial regression model, we found that directional changes in the timing of spring snowmelt and early summer rainfall (i.e., progressively drier summers) had moderate influences on annual fitness, with the latter statistically significant (ρ = -0.314 and 0.437, respectively). The summer period corresponds to prehibernation fattening of young and adult ground squirrels. Had we focused on a single point in time (viz. the onset of the breeding season), we would have underestimated the influences of climate change on our population. Rather, we obtained a comprehensive understanding of the influences of climate change on individual fitness by investigating the full lifecycle.

  17. Donning your enemy's cloak: ground squirrels exploit rattlesnake scent to reduce predation risk.

    PubMed

    Clucas, Barbara; Owings, Donald H; Rowe, Matthew P

    2008-04-07

    Ground squirrels (Spermophilus spp.) have evolved a battery of defences against the rattlesnakes (Crotalus spp.) that have preyed on them for millions of years. The distinctive behavioural reactions by these squirrels to rattlesnakes have recently been shown to include self-application of rattlesnake scent-squirrels apply scent by vigorously licking their fur after chewing on shed rattlesnake skins. Here, we present evidence that this behaviour is a novel antipredator defence founded on exploitation of a foreign scent. We tested three functional hypotheses for snake scent application--antipredator, conspecific deterrence and ectoparasite defence--by examining reactions to rattlesnake scent by rattlesnakes, ground squirrels and ectoparasites (fleas). Rattlesnakes were more attracted to ground squirrel scent than to ground squirrel scent mixed with rattlesnake scent or rattlesnake scent alone. However, ground squirrel behaviour and flea host choice were not affected by rattlesnake scent. Thus, ground squirrels can reduce the risk of rattlesnake predation by applying rattlesnake scent to their bodies, potentially as a form of olfactory camouflage. Opportunistic exploitation of heterospecific scents may be widespread; many species self-apply foreign odours, but few such cases have been demonstrated to serve in antipredator defence.

  18. Donning your enemy's cloak: ground squirrels exploit rattlesnake scent to reduce predation risk

    PubMed Central

    Clucas, Barbara; Owings, Donald H; Rowe, Matthew P

    2008-01-01

    Ground squirrels (Spermophilus spp.) have evolved a battery of defences against the rattlesnakes (Crotalus spp.) that have preyed on them for millions of years. The distinctive behavioural reactions by these squirrels to rattlesnakes have recently been shown to include self-application of rattlesnake scent—squirrels apply scent by vigorously licking their fur after chewing on shed rattlesnake skins. Here, we present evidence that this behaviour is a novel antipredator defence founded on exploitation of a foreign scent. We tested three functional hypotheses for snake scent application—antipredator, conspecific deterrence and ectoparasite defence—by examining reactions to rattlesnake scent by rattlesnakes, ground squirrels and ectoparasites (fleas). Rattlesnakes were more attracted to ground squirrel scent than to ground squirrel scent mixed with rattlesnake scent or rattlesnake scent alone. However, ground squirrel behaviour and flea host choice were not affected by rattlesnake scent. Thus, ground squirrels can reduce the risk of rattlesnake predation by applying rattlesnake scent to their bodies, potentially as a form of olfactory camouflage. Opportunistic exploitation of heterospecific scents may be widespread; many species self-apply foreign odours, but few such cases have been demonstrated to serve in antipredator defence. PMID:18198147

  19. Seasonal proteomic changes reveal molecular adaptations to preserve and replenish liver proteins during ground squirrel hibernation.

    PubMed

    Epperson, L Elaine; Rose, James C; Carey, Hannah V; Martin, Sandra L

    2010-02-01

    Hibernators are unique among mammals in their ability to survive extended periods of time with core body temperatures near freezing and with dramatically reduced heart, respiratory, and metabolic rates in a state known as torpor. To gain insight into the molecular events underlying this remarkable physiological phenotype, we applied a proteomic screening approach to identify liver proteins that differ between the summer active (SA) and the entrance (Ent) phase of winter hibernation in 13-lined ground squirrels. The relative abundance of 1,600 protein spots separated on two-dimensional gels was quantitatively determined using fluorescence difference gel electrophoresis, and 74 unique proteins exhibiting significant differences between the two states were identified using liquid chromatography followed by tandem mass spectrometry (LC-MS/MS). Proteins elevated in Ent hibernators included liver fatty acid-binding protein, fatty acid transporter, and 3-hydroxy-3-methylglutaryl-CoA synthase, which support the known metabolic fuel switch to lipid and ketone body utilization in winter. Several proteins involved in protein stability and protein folding were also elevated in the Ent phase, consistent with previous findings. In contrast to transcript screening results, there was a surprising increase in the abundance of proteins involved in protein synthesis during Ent hibernation, including several initiation and elongation factors. This finding, coupled with decreased abundance of numerous proteins involved in amino acid and nitrogen metabolism, supports the intriguing hypothesis that the mechanism of protein preservation and resynthesis is used by hibernating ground squirrels to help avoid nitrogen toxicity and ensure preservation of essential amino acids throughout the long winter fast.

  20. Influence of habitat on behavior of Towndsend's ground squirrels (Spermophilus townsendii)

    USGS Publications Warehouse

    Sharpe, Peter B.; Van Horne, Beatrice

    1998-01-01

    Trade-offs between foraging and predator avoidance may affect an animal's survival and reproduction. These trade-offs may be influenced by differences in vegetative cover, especially if foraging profitability and predation risk differ among habitats. We examined above-ground activity of Townsend's ground squirrels (Spermophilus townsendii) in four habitats in the Snake River Birds of Prey National Conservation Area in southwestern Idaho to determine if behavior of ground squirrels varied among habitats, and we assessed factors that might affect perceived predation risk (i. e. predator detectability, predation pressure, population density). The proportion of time spent in vigilance by ground squirrels in winterfat (Krascheninnikovia lanata) and mosaic habitats of winterfat-sagebrush (Artemisia tridentata) was more than twice that of ground squirrels in burned and unburned sagebrush habitats. We found no evidence for the 'many-eyes' hypothesis as an explanation for differences in vigilance among habitats. Instead, environmental heterogeneity, especially vegetation structure, likely influenced activity budgets of ground squirrels. Differences in vigilance may have been caused by differences in predator detectability and refuge availability, because ground squirrels in the winterfat and mosaic habitats also spent more time in upright vigilant postures than ground squirrels in burned-sagebrush or sagebrush habitats. Such postures may enhance predator detection in low-growing winterfat.

  1. Early Wisconsinan (MIS 4) Arctic ground squirrel middens and a squirrel-eye-view of the mammoth-steppe

    NASA Astrophysics Data System (ADS)

    Zazula, Grant D.; Froese, Duane G.; Elias, Scott A.; Kuzmina, Svetlana; Mathewes, Rolf W.

    2011-08-01

    Fossil arctic ground squirrel ( Spermophilus parryii) middens were recovered from ice-rich loess sediments in association with Sheep Creek-Klondike and Dominion Creek tephras (ca 80 ka) exposed in west-central Yukon. These middens provide plant and insect macrofossil evidence for a steppe-tundra ecosystem during the Early Wisconsinan (MIS 4) glacial interval. Midden plant and insect macrofossil data are compared with those previously published for Late Wisconsinan middens dating to ˜25-29 14C ka BP (MIS 3/2) from the region. Although multivariate statistical comparisons suggest differences between the relative abundances of plant macrofossils, the co-occurrence of steppe-tundra plants and insects (e.g., Elymus trachycaulus, Kobresia myosuroides, Artemisia frigida, Phlox hoodii, Connatichela artemisiae) provides evidence for successive reestablishment of the zonal steppe-tundra habitats during cold stages of the Late Pleistocene. Arctic ground squirrels were well adapted to the cold, arid climates, steppe-tundra vegetation and well-drained loessal soils that characterize cold stages of Late Pleistocene Beringia. These glacial conditions enabled arctic ground squirrel populations to expand their range to the interior regions of Alaska and Yukon, including the Klondike, where they are absent today. Arctic ground squirrels have endured numerous Quaternary climate oscillations by retracting populations to disjunct "interglacial refugia" during warm interglacial periods (e.g., south-facing steppe slopes, well-drained arctic and alpine tundra areas) and expanding their distribution across the mammoth-steppe biome during cold, arid glacial intervals.

  2. Ground squirrels use an infrared signal to deter rattlesnake predation

    PubMed Central

    Rundus, Aaron S.; Owings, Donald H.; Joshi, Sanjay S.; Chinn, Erin; Giannini, Nicolas

    2007-01-01

    The evolution of communicative signals involves a major hurdle; signals need to effectively stimulate the sensory systems of their targets. Therefore, sensory specializations of target animals are important sources of selection on signal structure. Here we report the discovery of an animal signal that uses a previously unknown communicative modality, infrared radiation or “radiant heat,” which capitalizes on the infrared sensory capabilities of the signal's target. California ground squirrels (Spermophilus beecheyi) add an infrared component to their snake-directed tail-flagging signals when confronting infrared-sensitive rattlesnakes (Crotalus oreganus), but tail flag without augmenting infrared emission when confronting infrared-insensitive gopher snakes (Pituophis melanoleucus). Experimental playbacks with a biorobotic squirrel model reveal this signal's communicative function. When the infrared component was added to the tail flagging display of the robotic models, rattlesnakes exhibited a greater shift from predatory to defensive behavior than during control trials in which tail flagging included no infrared component. These findings provide exceptionally strong support for the hypothesis that the sensory systems of signal targets should, in general, channel the evolution of signal structure. Furthermore, the discovery of previously undescribed signaling modalities such as infrared radiation should encourage us to overcome our own human-centered sensory biases and more fully examine the form and diversity of signals in the repertoires of many animal species. PMID:17704254

  3. Enhanced oxidative capacity of ground squirrel brain mitochondria during hibernation.

    PubMed

    Ballinger, Mallory A; Schwartz, Christine; Andrews, Matthew T

    2017-03-01

    During hibernation, thirteen-lined ground squirrels (Ictidomys tridecemlineatus) regularly cycle between bouts of torpor and interbout arousal (IBA). Most of the brain is electrically quiescent during torpor but regains activity quickly upon arousal to IBA, resulting in extreme oscillations in energy demand during hibernation. We predicted increased functional capacity of brain mitochondria during hibernation compared with spring to accommodate the variable energy demands of hibernation. To address this hypothesis, we examined mitochondrial bioenergetics in the ground squirrel brain across three time points: spring (SP), torpor (TOR), and IBA. Respiration rates of isolated brain mitochondria through complex I of the electron transport chain were more than twofold higher in TOR and IBA than in SP (P < 0.05). We also found a 10% increase in membrane potential between hibernation and spring (P < 0.05), and that proton leak was lower in TOR and IBA than in SP. Finally, there was a 30% increase in calcium loading in SP brain mitochondria compared with TOR and IBA (P < 0.01). To analyze brain mitochondrial abundance between spring and hibernation, we measured the ratio of copy number in a mitochondrial gene (ND1) vs. a nuclear gene (B2M) in frozen cerebral cortex samples. No significant differences were observed in DNA copies between SP and IBA. These data show that brain mitochondrial bioenergetics are not static across the year and suggest that brain mitochondria function more effectively during the hibernation season, allowing for rapid production of energy to meet demand when extreme physiological changes are occurring.

  4. Ground-squirrel mounds and related patterned ground along the San Andreas Fault in Central California

    USGS Publications Warehouse

    Wallace, Robert E.

    1991-01-01

    Extensive areas of mound topography and related patterned ground, apparently derived from the mounds of the California Ground Squirrel (Spermophilus beecheyi beecheyi), are in central California.  The relation of patterned ground to the San Andreas fault west of Bakersfield may provide insight into the timing of deformation along the fault as well as the history of ground squirrels.  Mound topography appears to have evolved through several stages from scattered mounds currently being constructed on newly deposited alluvial surfaces, to saturation of areas by mounds, followed by coalescence, elongation and lineation of the mounds.  Elongation, coalescence and modification of the mounds has been primarily by wind, but to a lesser extent by drainage and solifluction.  A time frame including ages of 4,000, 10,500, 29,000, and 73,000 years BP is derived by relating the patterns to slip on the San Andreas fault.  Further relating of the patterns to faulting, tilting, and warping may illuminate details of the rates and history of deformation.  Similarly, relating the patterns to the history of ground squirrel activity may help answer such problems as rates of dispersal and limits on population density.

  5. Daily rhythmicity and hibernation in the Anatolian ground squirrel under natural and laboratory conditions.

    PubMed

    Kart Gür, Mutlu; Refinetti, Roberto; Gür, Hakan

    2009-02-01

    We studied daily rhythmicity of body temperature (T(b)) before and during hibernation in Anatolian ground squirrels (Spermophilus xanthoprymnus) under natural and laboratory conditions using surgically implanted temperature loggers. Under both conditions, robust daily T(b) rhythmicity with parameters comparable to those of other ground squirrel species was observed before but not during hibernation. Euthermic animals had robust daily T(b) rhythms with a mean of 37.0 degrees C and a range of excursion of approximately 4 degrees C. No T(b) rhythm was detected during torpor bouts, either because T(b) rhythmicity was absent or because the daily range of excursion was smaller than 0.2 degrees C. The general patterns of hibernation that we observed in Anatolian ground squirrels were similar to those previously observed by other investigators in other species of ground squirrels.

  6. Ground Squirrel Shooting and Potential Lead Exposure in Breeding Avian Scavengers

    PubMed Central

    Eagles-Smith, Collin A.; Wagner, Mason T.

    2016-01-01

    Recreational ground squirrel shooting is a popular activity throughout the western United States and serves as a tool for managing ground squirrel populations in agricultural regions. Belding’s ground squirrels (Spermophilus beldingi) are routinely shot in California, Nevada, and Oregon across habitats that overlap with breeding avian scavengers. Ground squirrels shot with lead (Pb)-based bullets may pose a risk to avian scavengers if they consume carcasses containing Pb fragments. To assess the potential risk to breeding avian scavengers we developed a model to estimate the number, mass, and distribution of Pb fragments in shot ground squirrels using radiographic images. Eighty percent of shot carcasses contained detectible Pb fragments with an average of 38.6 mg of Pb fragments. Seven percent of all carcasses contained Pb fragment masses exceeding a lethal dose for a model raptor nestling (e.g. American kestrel Falco sparverius). Bullet type did not influence the number of fragments in shot ground squirrels, but did influence the mass of fragments retained. Belding’s ground squirrels shot with .17 Super Mag and unknown ammunition types contained over 28 and 17 times more mass of Pb fragments than those shot with .22 solid and .22 hollow point bullets, respectively. Ground squirrel body mass was positively correlated with both the number and mass of Pb fragments in carcasses, increasing on average by 76% and 56% respectively across the range of carcass masses. Although the mass of Pb retained in ground squirrel carcasses was small relative to the original bullet mass, avian scavenger nestlings that frequently consume shot ground squirrels may be at risk for Pb-induced effects (e.g., physiology, growth, or survival). Using modeling efforts we found that if nestling golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), and Swainson’s hawks (B. swainsoni) consumed shot ground squirrels proportionately to the nestling’s mass, energy needs

  7. Ground Squirrel Shooting and Potential Lead Exposure in Breeding Avian Scavengers.

    PubMed

    Herring, Garth; Eagles-Smith, Collin A; Wagner, Mason T

    2016-01-01

    Recreational ground squirrel shooting is a popular activity throughout the western United States and serves as a tool for managing ground squirrel populations in agricultural regions. Belding's ground squirrels (Spermophilus beldingi) are routinely shot in California, Nevada, and Oregon across habitats that overlap with breeding avian scavengers. Ground squirrels shot with lead (Pb)-based bullets may pose a risk to avian scavengers if they consume carcasses containing Pb fragments. To assess the potential risk to breeding avian scavengers we developed a model to estimate the number, mass, and distribution of Pb fragments in shot ground squirrels using radiographic images. Eighty percent of shot carcasses contained detectible Pb fragments with an average of 38.6 mg of Pb fragments. Seven percent of all carcasses contained Pb fragment masses exceeding a lethal dose for a model raptor nestling (e.g. American kestrel Falco sparverius). Bullet type did not influence the number of fragments in shot ground squirrels, but did influence the mass of fragments retained. Belding's ground squirrels shot with .17 Super Mag and unknown ammunition types contained over 28 and 17 times more mass of Pb fragments than those shot with .22 solid and .22 hollow point bullets, respectively. Ground squirrel body mass was positively correlated with both the number and mass of Pb fragments in carcasses, increasing on average by 76% and 56% respectively across the range of carcass masses. Although the mass of Pb retained in ground squirrel carcasses was small relative to the original bullet mass, avian scavenger nestlings that frequently consume shot ground squirrels may be at risk for Pb-induced effects (e.g., physiology, growth, or survival). Using modeling efforts we found that if nestling golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), and Swainson's hawks (B. swainsoni) consumed shot ground squirrels proportionately to the nestling's mass, energy needs, and diet

  8. Ground squirrel shooting and potential lead exposure in breeding avian scavengers

    USGS Publications Warehouse

    Herring, Garth; Eagles-Smith, Collin A.; Wagner, Mason T.

    2016-01-01

    Recreational ground squirrel shooting is a popular activity throughout the western United States and serves as a tool for managing ground squirrel populations in agricultural regions. Belding’s ground squirrels (Spermophilus beldingi) are routinely shot in California, Nevada, and Oregon across habitats that overlap with breeding avian scavengers. Ground squirrels shot with lead (Pb)-based bullets may pose a risk to avian scavengers if they consume carcasses containing Pb fragments. To assess the potential risk to breeding avian scavengers we developed a model to estimate the number, mass, and distribution of Pb fragments in shot ground squirrels using radiographic images. Eighty percent of shot carcasses contained detectible Pb fragments with an average of 38.6 mg of Pb fragments. Seven percent of all carcasses contained Pb fragment masses exceeding a lethal dose for a model raptor nestling (e.g. American kestrel Falco sparverius). Bullet type did not influence the number of fragments in shot ground squirrels, but did influence the mass of fragments retained. Belding’s ground squirrels shot with .17 Super Mag and unknown ammunition types contained over 28 and 17 times more mass of Pb fragments than those shot with .22 solid and .22 hollow point bullets, respectively. Ground squirrel body mass was positively correlated with both the number and mass of Pb fragments in carcasses, increasing on average by 76% and 56% respectively across the range of carcass masses. Although the mass of Pb retained in ground squirrel carcasses was small relative to the original bullet mass, avian scavenger nestlings that frequently consume shot ground squirrels may be at risk for Pb-induced effects (e.g., physiology, growth, or survival). Using modeling efforts we found that if nestling golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), and Swainson’s hawks (B. swainsoni) consumed shot ground squirrels proportionately to the nestling’s mass, energy needs

  9. Increased Na+/Ca2+ exchanger activity promotes resistance to excitotoxicity in cortical neurons of the ground squirrel (a Hibernator).

    PubMed

    Zhao, Juan-Juan; Gao, Shan; Jing, Jun-Zhan; Zhu, Ming-Yue; Zhou, Chen; Chai, Zhen

    2014-01-01

    Ground squirrel, a hibernating mammalian species, is more resistant to ischemic brain stress than rat. Gaining insight into the adaptive mechanisms of ground squirrels may help us design treatment strategies to reduce brain damage in patients suffering ischemic stroke. To understand the anti-stress mechanisms in ground squirrel neurons, we studied glutamate toxicity in primary cultured neurons of the Daurian ground squirrel (Spermophilus dauricus). At the neuronal level, for the first time, we found that ground squirrel was more resistant to glutamate excitotoxicity than rat. Mechanistically, ground squirrel neurons displayed a similar calcium influx to the rat neurons in response to glutamate or N-methyl-D-aspartate (NMDA) perfusion. However, the rate of calcium removal in ground squirrel neurons was markedly faster than in rat neurons. This allows ground squirrel neurons to maintain lower level of intracellular calcium concentration ([Ca2+]i) upon glutamate insult. Moreover, we found that Na+/Ca2+ exchanger (NCX) activity was higher in ground squirrel neurons than in rat neurons. We also proved that overexpression of ground squirrel NCX2, rather than NCX1 or NCX3, in rat neurons promoted neuron survival against glutamate toxicity. Taken together, our results indicate that ground squirrel neurons are better at maintaining calcium homeostasis than rat neurons and this is likely achieved through the activity of ground squirrel NCX2. Our findings not only reveal an adaptive mechanism of mammalian hibernators at the cellular level, but also suggest that NCX2 of ground squirrel may have therapeutic value for suppressing brain ischemic damage.

  10. Seasonal and post-trauma remodeling in cone-dominant ground squirrel retina.

    PubMed

    Merriman, Dana K; Sajdak, Benjamin S; Li, Wei; Jones, Bryan W

    2016-09-01

    With a photoreceptor mosaic containing ∼85% cones, the ground squirrel is one of the richest known mammalian sources of these important retinal cells. It also has a visual ecology much like the human's. While the ground squirrel retina is understandably prominent in the cone biochemistry, physiology, and circuitry literature, far less is known about the remodeling potential of its retinal pigment epithelium, neurons, macroglia, or microglia. This review aims to summarize the data from ground squirrel retina to this point in time, and to relate them to data from other brain areas where appropriate. We begin with a survey of the ground squirrel visual system, making comparisons with traditional rodent models and with human. Because this animal's status as a hibernator often goes unnoticed in the vision literature, we then present a brief primer on hibernation biology. Next we review what is known about ground squirrel retinal remodeling concurrent with deep torpor and with rapid recovery upon re-warming. Notable here is rapidly-reversible, temperature-dependent structural plasticity of cone ribbon synapses, as well as pre- and post-synaptic plasticity throughout diverse brain regions. It is not yet clear if retinal cell types other than cones engage in torpor-associated synaptic remodeling. We end with the small but intriguing literature on the ground squirrel retina's remodeling responses to insult by retinal detachment. Notable for widespread loss of (cone) photoreceptors, there is surprisingly little remodeling of the RPE or Müller cells. Microglial activation appears minimal, and remodeling of surviving second- and third-order neurons seems absent, but both require further study. In contrast, traumatic brain injury in the ground squirrel elicits typical macroglial and microglial responses. Overall, the data to date strongly suggest a heretofore unrecognized, natural checkpoint between retinal deafferentiation and RPE and Müller cell remodeling events. As we

  11. Phospholipids of liver cell nuclei during hibernation of Yakutian ground squirrel.

    PubMed

    Lakhina, A A; Markevich, L N; Zakharova, N M; Afanasyev, V N; Kolomiytseva, I K; Fesenko, E E

    2016-07-01

    In hibernating Yakutian ground squirrels S. undulatus, the content of total phospholipids in the nuclei of liver increased by 40% compared to that in animals in summer. In torpid state, the amount of sphingomyelin increased almost 8 times; phosphatidylserine, 7 times; and cardiolipin, 4 times. In active "winter" ground squirrels, the amount of sphingomyelin, phosphatidylserine, and cardiolipin decreased compared to the hibernating individuals but remained high compared to the "summer" ones. The torpor state did not affect the amount of lysophosphatidylcholine and phosphatidylinositol.

  12. Seasonal change in irradiance: a zeitgeber for circannual rhythms in ground squirrels.

    PubMed

    Davis, D E

    1991-01-01

    1. Zeitgebers for circannual rhythms have been elusive. Demonstration that an external factor is a zeitgeber requires proof of a phase-shift that endures for several years. 2. The California ground squirrel (Spermophilus beecheyi) is an ideal subject. Many features of behavior have circannual rhythms of which change in mass is the easiest to measure. The squirrels thrive in captivity for up to 10 years. The squirrels were kept in individual cages in an air conditioned room, fed lab chow ad lib, and weighed twice a month. They were exposed to a 6-month phase shift of (a) length of day (b) seasonal change in temperature, (c) both, (d) seasonal cycle of irradiance. 3. The squirrels maintained circannual rhythms for up to 9 years. Entrainment was evident only by squirrels exposed to seasonal change in irradiance.

  13. Membrane lipids and morphology of brain cortex synaptosomes isolated from hibernating Yakutian ground squirrel.

    PubMed

    Kolomiytseva, Iskra K; Perepelkina, Natalia I; Zharikova, Alevtina D; Popov, Victor I

    2008-12-01

    Synaptosomes were isolated from Yakutian ground squirrel brain cortex of summer and winter hibernating animals in active and torpor states. Synaptosomal membrane cholesterol and phospholipids were determined. The seasonal changes of synaptosomal lipid composition were found. Synaptosomes isolated from hibernating Yakutian ground squirrel brain cortex maintained the cholesterol sphingomyelin, phosphatidylethanolamine, lysophosphatidylcholine, cardiolipin, phosphatidylinositol and phosphatidylserine contents 2.5, 1.8, 2.6, 1.8, 1.6, and 1.3 times less, respectively, and the content of phosphatidylcholine twice as much as the one in summer season. The synaptosomal membrane lipid composition of summer animals was shown to be markedly different from that as hibernating ground squirrels and non-hibernating rodents. It is believed that phenotypic changes of synaptosomal membrane lipid composition in summer Yakutian ground squirrel are the important preparation step for hibernation. The phosphatidylethanolamine content was increased in torpor state compared with winter-active state and the molar ratio of cholesterol/phospholipids in synaptosomal membrane of winter torpor ground squirrels was lower than that in active winter and summer animals. These events were supposed to lead to increase of the synaptosomal membrane fluidity during torpor. Synaptosomes isolated from torpor animals have larger sizes and contain a greater number of synaptic vesicles on the synaptosomal profile area. The synaptosomal membrane lipid composition and synaptosome morphology were involved in phenotypic adaptation of Yakutian ground squirrel to hibernation.

  14. [Phylogeny of genus Spermophilus and position of Alashan ground squirrel (Spermophilus alashanicus, Buchner, 1888) on phylogenetic tree of Paleartic short-tailed ground squirrels].

    PubMed

    Kapustina, S Yu; Brandler, O V; Adiya, Ya

    2015-01-01

    Phylogenetic relationships within a group of Paleartic short tailed ground squirrels (Spermophilus), recently defined as genus, are not sufficiently clear and need a critical revision. Interspecies hybridization, found in Eurasian Spermophilus, can affect the results of reconstruction of molecular phylogeny. Alashan ground squirrel position on the phylogenetic tree needs clarification. We analyzed eight nucleotide sequences of cytb gene of S. alashanicus and 127 sequences of other Spermophilus species form GenBank. S.alashanicus and S. dauricus close phylogenetic relationship, and their affinity to ancestral forms of the group are revealed. Monophyly of Colobotis subgenus was confirmed. Paraphyly of eastern and western forms of S. relictus was shown.

  15. Home range, social behavior, and dominance relationships in the African unstriped ground squirrel, Xerus rutilus

    USGS Publications Warehouse

    O'Shea, Thomas J.

    1976-01-01

    A field study of home range, social behavior, and dominance relationships in the African unstriped ground squirrel, Xerus rutilus, was conducted in semi-arid bushland near Kibwezi, Kenya. Ground squirrels lived alone or in small groups in isolated burrow systems and had broadly overlapping home ranges. They were neither territorial or colonial. Home ranges were estimated by visual observation of marked animals and those of males were considerably larger (mean=7.01 hectares (ha); n=4) than those of females (mean=1.37 ha; n-6). A continuum of agonistic behavior ranging from threat to combat is described, although actual combat was rarely observed. Sexual behavior includes a stereotypical tail display by adult males. Dominance relationships, based on 542 observed encounters between marked individuals, include a consistent male dominance over females and a fairly constant linear hierarchy among all individuals with shared home ranges. Similarities in the behavior of African ground squirrels and tree squirrels (Sciurus) are discussed.

  16. Will Arctic ground squirrels impede or accelerate climate-induced vegetation changes to the Arctic tundra?

    NASA Astrophysics Data System (ADS)

    Dalton, J.; Flower, C. E.; Brown, J.; Gonzalez-Meler, M. A.; Whelan, C.

    2014-12-01

    Considerable attention has been given to the climate feedbacks associated with predicted vegetation shifts in the Arctic tundra in response to global environmental change. However, little is known regarding the extent to which consumers can facilitate or respond to shrub expansion. Arctic ground squirrels, the largest and most northern ground squirrel, are abundant and widespread throughout the North American tundra. Their broad diet of seeds, flowers, herbage, bird's eggs and meat speaks to the need to breed, feed, and fatten in a span of some 12-16 weeks that separate their 8-9 month bouts of hibernation with the potential consequence to impact ecosystem dynamics. Therefore Arctic ground squirrels are a good candidate to evaluate whether consumers are mere responders (bottom-up effects) or drivers (top-down) of the observed and predicted vegetation changes. As a start towards this question, we measured the foraging intensity (giving-up densities) of Arctic ground squirrels in experimental food patches within which the squirrels experience diminishing returns as they seek the raisins and peanuts that we provided at the Toolik Lake field station in northern Alaska. If the squirrels show their highest feeding intensity in the shrubs, they may impede vegetation shifts by slowing the establishment and expansion of shrubs in the tundra. Conversely, if they show their lowest feeding intensity within shrub dominated areas, they may accelerate vegetation shifts. We found neither. Feeding intensity varied most among transects and times of day, and least along a tundra-to-shrub vegetation gradient. This suggests that the impacts of squirrels will be heterogeneous - in places responders and in others drivers. We should not be surprised then to see patches of accelerated and impeded vegetation changes in the tundra ecosystem. Some of these patterns may be predictable from the foraging behavior of Arctic ground squirrels.

  17. Use of burrow entrances to indicate densities of Townsend's ground squirrels

    USGS Publications Warehouse

    Van Horne, Beatrice; Schooley, R.L.; Knick, Steven T.; Olson, G.S.; Burnham, K.P.

    1997-01-01

    Counts of burrow entrances have been positively correlated with densities of semi-fossorial rodents and used as an index of densities. We evaluated their effectiveness in indexing densities of Townsend's ground squirrels (Spermophilus townsendii) in the Snake River Birds of Prey National Conservation Area (SRBOPNCA), Idaho, by comparing burrow entrance densities to densities of ground squirrels estimated from livetrapping in 2 consecutive years over which squirrel populations declined by >75%. We did not detect a consistent relation between burrow entrance counts and ground squirrel density estimates within or among habitat types. Scatter plots indicated that burrow entrances had little predictive power at intermediate densities. Burrow entrance counts did not reflect the magnitude of a between-year density decline. Repeated counts of entrances late in the squirrels' active season varied in a manner that would be difficult to use for calibration of transects sampled only once during this period. Annual persistence of burrow entrances varied between habitats. Trained observers were inconsistent in assigning active-inactive status to entrances. We recommend that burrow entrance counts not be used as measures or indices of ground squirrel densities in shrubsteppe habitats, and that the method be verified thoroughly before being used in other habitats.

  18. Ectoparasites and fitness of female Columbian ground squirrels.

    PubMed

    Raveh, Shirley; Neuhaus, Peter; Dobson, F Stephen

    2015-05-26

    Parasites play an important role in the evolution of host traits via natural selection, coevolution and sexually selected ornaments used in mate choice. These evolutionary scenarios assume fitness costs for hosts. To test this assumption, we conducted an ectoparasite removal experiment in free-living Columbian ground squirrels (Urocittelus columbianus) in four populations over three years. Adult females were randomly chosen to be either experimentally treated with anti-parasite treatments (spot-on solution and flea powder, N = 61) or a sham treatment (control, N = 44). We expected that experimental females would show better body condition, increased reproductive success and enhanced survival. Contrary to our expectations, body mass was not significantly different between treatments at mating, birth of litter or weaning of young. Further, neither number nor size of young at weaning differed significantly between the two treatments. Survival to the next spring for adult females and juveniles was not significantly different between experimental and control treatments. Finally, annual fitness was not affected by the treatments. We concluded that females and their offspring were able compensate for the presence of ectoparasites, suggesting little or no fitness costs of parasites for females in the different colonies and during the years of our experiments.

  19. The complete mitochondrial genome of Daurian ground squirrel, Spermophilus dauricus.

    PubMed

    Jin, Guang-Yao; Huang, Hai-Jiao; Zhang, Ming-Hai

    2016-07-01

    The mitochondrial genome sequence of Daurian ground squirrel, Spermophilus dauricus, is determined and described for the first time in this study. The genome was a total of 16 512 bp in length and had a base composition of A (32.08%), G (12.53%), C (24.35%), and T (31.04%), indicating that the percentage of A + T (63.12%) is higher than G + C (36.88%). Similar to those reported from other animal mitochondrial genomes, it possessed a typically conserved structure, including 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 1 control region (D-loop). Most of these genes were found to locate on the H-strand except for the ND6 gene and 8 tRNA genes. The phylogenetic analysis showed Spermophilus dauricus formed the sister group to the Pteromyini tribe. This mitochondrial genome sequence would supply useful genetic resources to uncover Sciuridae family evolution.

  20. Blood cell dynamics during hibernation in the European Ground Squirrel.

    PubMed

    Bouma, H R; Strijkstra, A M; Boerema, A S; Deelman, L E; Epema, A H; Hut, R A; Kroese, F G M; Henning, R H

    2010-08-15

    Hibernation is a unique natural model to study large and specific modulation in numbers of leukocytes and thrombocytes, with potential relevance for medical application. Hibernating animals cycle through cold (torpor) and warm (arousal) phases. Previous research demonstrated clearance of leukocytes and thrombocytes from the circulation during torpor, but did not provide information regarding the timing during torpor or the subtype of leukocytes affected. To study the influence of torpor-bout duration on clearance of circulating cells, we measured blood cell dynamics in the European Ground Squirrel. Numbers of leukocytes and thrombocytes decreased within 24h of torpor by 90% and remained unchanged during the remainder of the torpor-bout. Differential counts demonstrated that granulocytes, lymphocytes and monocytes are all affected by torpor. Although a decreased production might explain the reduced number of thrombocytes, granulocytes and monocytes, this cannot explain the observed lymphopenia since lymphocytes have a much lower turnover rate than thrombocytes, granulocytes and monocytes. In conclusion, although underlying biochemical signaling pathways need to be unraveled, our data show that the leukocyte count drops dramatically after entrance into torpor and that euthermic cell counts are restored within 1.5h after onset of arousal, even before body temperature is fully normalized.

  1. Organizational motifs for ground squirrel cone bipolar cells.

    PubMed

    Light, Adam C; Zhu, Yongling; Shi, Jun; Saszik, Shannon; Lindstrom, Sarah; Davidson, Laura; Li, Xiaoyu; Chiodo, Vince A; Hauswirth, William W; Li, Wei; DeVries, Steven H

    2012-09-01

    In daylight vision, parallel processing starts at the cone synapse. Cone signals flow to On and Off bipolar cells, which are further divided into types according to morphology, immunocytochemistry, and function. The axons of the bipolar cell types stratify at different levels in the inner plexiform layer (IPL) and can interact with costratifying amacrine and ganglion cells. These interactions endow the ganglion cell types with unique functional properties. The wiring that underlies the interactions among bipolar, amacrine, and ganglion cells is poorly understood. It may be easier to elucidate this wiring if organizational rules can be established. We identify 13 types of cone bipolar cells in the ground squirrel, 11 of which contact contiguous cones, with the possible exception of short-wavelength-sensitive cones. Cells were identified by antibody labeling, tracer filling, and Golgi-like filling following transduction with an adeno-associated virus encoding for green fluorescent protein. The 11 bipolar cell types displayed two organizational patterns. In the first pattern, eight to 10 of the 11 types came in pairs with partially overlapping axonal stratification. Pairs shared morphological, immunocytochemical, and functional properties. The existence of similar pairs is a new motif that might have implications for how signals first diverge from a cone to bipolar cells and then reconverge onto a costratifying ganglion cell. The second pattern is a mirror symmetric organization about the middle of the IPL involving at least seven bipolar cell types. This anatomical symmetry may be associated with a functional symmetry in On and Off ganglion cell responses.

  2. Ectoparasites and fitness of female Columbian ground squirrels

    PubMed Central

    Raveh, Shirley; Neuhaus, Peter; Dobson, F. Stephen

    2015-01-01

    Parasites play an important role in the evolution of host traits via natural selection, coevolution and sexually selected ornaments used in mate choice. These evolutionary scenarios assume fitness costs for hosts. To test this assumption, we conducted an ectoparasite removal experiment in free-living Columbian ground squirrels (Urocittelus columbianus) in four populations over three years. Adult females were randomly chosen to be either experimentally treated with anti-parasite treatments (spot-on solution and flea powder, N = 61) or a sham treatment (control, N = 44). We expected that experimental females would show better body condition, increased reproductive success and enhanced survival. Contrary to our expectations, body mass was not significantly different between treatments at mating, birth of litter or weaning of young. Further, neither number nor size of young at weaning differed significantly between the two treatments. Survival to the next spring for adult females and juveniles was not significantly different between experimental and control treatments. Finally, annual fitness was not affected by the treatments. We concluded that females and their offspring were able compensate for the presence of ectoparasites, suggesting little or no fitness costs of parasites for females in the different colonies and during the years of our experiments. PMID:25870399

  3. Regulation of glucokinase activity in liver of hibernating ground squirrel Spermophilus undulatus.

    PubMed

    Khu, L Ya; Storey, K B; Rubtsov, A M; Goncharova, N Yu

    2014-07-01

    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 active and hibernating ground squirrels. The dependence of GLK activity upon Glc concentration for the enzyme from active ground squirrel liver showed a pronounced sigmoid character (Hill coefficient, h=1.70 and S0.5=6.23 mM; the experiments were conducted at 25°C in the presence of enzyme stabilizers, K+ and DTT). The same dependence of enzyme activity on Glc concentration was found for GLK from rat liver. However, on decreasing the temperature to 2°C (simulation of hibernation conditions), this dependency became almost hyperbolic (h=1.16) and GLK affinity for substrate was reduced (S0.5=23 mM). These parameters for hibernating ground squirrels (body temperature 5°C) at 25°C were found to be practically equal to the corresponding values obtained for GLK from the liver of active animals (h=1.60, S0.5=9.0 mM, respectively); at 2°C sigmoid character was less expressed and affinity for Glc was drastically decreased (h=1.20, S0.5=45 mM). The calculations of GLK activity in the liver of hibernating ground squirrels based on enzyme kinetic characteristics and seasonal changes in blood Glc concentrations have shown that GLK activity in the liver of hibernating ground squirrels is decreased about 5500-fold.

  4. California ground squirrel (Spermophilus beecheyi) defenses against rattlesnake venom digestive and hemostatic toxins.

    PubMed

    Biardi, James E; Chien, David C; Coss, Richard G

    2006-01-01

    Previous studies have shown that some mammals are able to neutralize venom from snake predators. California ground squirrels (Spermophilus beecheyi) show variation among populations in their ability to bind venom and minimize damage from northern Pacific rattlesnakes (Crotalus oreganus), but the venom toxins targeted by resistance have not been investigated. Four California ground squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for their ability to neutralize digestive and hemostatic effects of venom from three rattlesnake species. In Douglas ground squirrels (S. b. douglasii), we found that animals from a location where snakes are common showed greater inhibition of venom metalloprotease and hemolytic activity than animals from a location where snakes are rare. Effects on general proteolysis were not different. Douglas ground squirrels also reduced the metalloprotease activity of venom from sympatric northern Pacific rattlesnakes (C. o. oreganus) more than the activity of venom from allopatric western diamondback rattlesnakes (C. atrox), but enhanced the fibrinolysis of sympatric venom almost 1.8 times above baseline levels. Two Beechey ground squirrel (S. b. beecheyi) populations had similar inhibition of venoms from northern and southern Pacific rattlesnakes (C. o. helleri), despite differences between the populations in the locally prevalent predator. However, the venom toxins inhibited by Beechey squirrels varied among venom from Pacific rattlesnake subspecies, and between these venoms and venom from allopatric western diamondback rattlesnakes. Blood plasma from Beechey squirrels showed highest inhibition of metalloprotease activity of northern Pacific rattlesnake venom, general proteolytic activity and hemolysis of southern Pacific rattlesnake venom, and hemolysis by allopatric western diamondback venom. These results reveal previously cryptic variation in venom activity against resistant prey

  5. California ground squirrel (Spermophilus beecheyi) defenses against rattlesnake venom digestive and hemostatic toxins.

    PubMed

    Biardi, James E; Chien, David C; Coss, Richard G

    2005-11-01

    Previous studies have shown that some mammals are able to neutralize venom from snake predators. California ground squirrels (Spermophilus beecheyi) show variation among populations in their ability to bind venom and minimize damage from northern Pacific rattlesnakes (Crotalus oreganus), but the venom toxins targeted by resistance have not been investigated. Four California ground squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for their ability to neutralize digestive and hemostatic effects of venom from three rattlesnake species. In Douglas ground squirrels (S. b. douglasii), we found that animals from a location where snakes are common showed greater inhibition of venom metalloprotease and hemolytic activity than animals from a location where snakes are rare. Effects on general proteolysis were not different. Douglas ground squirrels also reduced the metalloprotease activity of venom from sympatric northern Pacific rattlesnakes (Crotalus oreganus oreganus) more than the activity of venom from allopatric western diamondback rattlesnakes (C. atrox), but enhanced fibrinolysis of sympatric venom almost 1.8 times above baseline levels. Two Beechey ground squirrel (S. b. beecheyi) populations had similar inhibition of venoms from northern and southern Pacific rattlesnakes (C. o. helleri), despite differences between the populations in the locally prevalent predator. However, the venom toxins inhibited by Beechey squirrels did vary among venom from Pacific rattlesnake subspecies, and between these venoms and venom from allopatric western diamondback rattlesnakes. Blood plasma from Beechey squirrels showed highest inhibition of metalloprotease activity of northern Pacific rattlesnake venom, general proteolytic activity and hemolysis of southern Pacific rattlesnake venom, and hemolysis by allopatric western diamondback venom. These results reveal previously cryptic variation in venom activity against

  6. Stochastic Population Dynamics of a Montane Ground-Dwelling Squirrel

    PubMed Central

    Hostetler, Jeffrey A.; Kneip, Eva; Van Vuren, Dirk H.; Oli, Madan K.

    2012-01-01

    Understanding the causes and consequences of population fluctuations is a central goal of ecology. We used demographic data from a long-term (1990–2008) study and matrix population models to investigate factors and processes influencing the dynamics and persistence of a golden-mantled ground squirrel (Callospermophilus lateralis) population, inhabiting a dynamic subalpine habitat in Colorado, USA. The overall deterministic population growth rate λ was 0.94±SE 0.05 but it varied widely over time, ranging from 0.45±0.09 in 2006 to 1.50±0.12 in 2003, and was below replacement (λ<1) for 9 out of 18 years. The stochastic population growth rate λs was 0.92, suggesting a declining population; however, the 95% CI on λs included 1.0 (0.52–1.60). Stochastic elasticity analysis showed that survival of adult females, followed by survival of juvenile females and litter size, were potentially the most influential vital rates; analysis of life table response experiments revealed that the same three life history variables made the largest contributions to year-to year changes in λ. Population viability analysis revealed that, when the influences of density dependence and immigration were not considered, the population had a high (close to 1.0 in 50 years) probability of extinction. However, probability of extinction declined to as low as zero when density dependence and immigration were considered. Destabilizing effects of stochastic forces were counteracted by regulating effects of density dependence and rescue effects of immigration, which allowed our study population to bounce back from low densities and prevented extinction. These results suggest that dynamics and persistence of our study population are determined synergistically by density-dependence, stochastic forces, and immigration. PMID:22479616

  7. Stochastic population dynamics of a montane ground-dwelling squirrel.

    PubMed

    Hostetler, Jeffrey A; Kneip, Eva; Van Vuren, Dirk H; Oli, Madan K

    2012-01-01

    Understanding the causes and consequences of population fluctuations is a central goal of ecology. We used demographic data from a long-term (1990-2008) study and matrix population models to investigate factors and processes influencing the dynamics and persistence of a golden-mantled ground squirrel (Callospermophilus lateralis) population, inhabiting a dynamic subalpine habitat in Colorado, USA. The overall deterministic population growth rate λ was 0.94±SE 0.05 but it varied widely over time, ranging from 0.45±0.09 in 2006 to 1.50±0.12 in 2003, and was below replacement (λ<1) for 9 out of 18 years. The stochastic population growth rate λ(s) was 0.92, suggesting a declining population; however, the 95% CI on λ(s) included 1.0 (0.52-1.60). Stochastic elasticity analysis showed that survival of adult females, followed by survival of juvenile females and litter size, were potentially the most influential vital rates; analysis of life table response experiments revealed that the same three life history variables made the largest contributions to year-to year changes in λ. Population viability analysis revealed that, when the influences of density dependence and immigration were not considered, the population had a high (close to 1.0 in 50 years) probability of extinction. However, probability of extinction declined to as low as zero when density dependence and immigration were considered. Destabilizing effects of stochastic forces were counteracted by regulating effects of density dependence and rescue effects of immigration, which allowed our study population to bounce back from low densities and prevented extinction. These results suggest that dynamics and persistence of our study population are determined synergistically by density-dependence, stochastic forces, and immigration.

  8. [Seasonal changes in mechanical resistance of erythrocytes of the long-tailed ground squirrel (Citellus undulatus)].

    PubMed

    Gulevsky, A K; Shchenyavsky, I I

    2014-01-01

    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 increase in free plasma hemoglobin at these periods. It has been also shown that erythrocytes of hibernating and forcibly awaken winter ground squirrels have a significantly lower mechanical resistance in comparison with those of active summer animals. The obtained data indicate that during the periods preceding the onset of winter hibernation and transition to summer activity there occurs a seasonal replacement of the erythrocyte pool by a pool more adapted to performance of functions in the novel functional state of the animal-hibernator.

  9. Individual acoustic variation in Belding's ground squirrel alarm chirps in the High Sierra Nevada

    NASA Astrophysics Data System (ADS)

    McCowan, Brenda; Hooper, Stacie L.

    2002-03-01

    The acoustic structure of calls within call types can vary as function of individual identity, sex, and social group membership and is important in kin and social group recognition. Belding's ground squirrels (Spermophilus beldingi) produce alarm chirps that function in predator avoidance but little is known about the acoustic variability of these alarm chirps. The purpose of this preliminary study was to analyze the acoustic structure of alarm chirps with respect to individual differences (e.g., signature information) from eight Belding's ground squirrels from four different lakes in the High Sierra Nevada. Results demonstrate that alarm chirps are individually distinctive, and that acoustic similarity among individuals may correspond to genetic similarity and thus dispersal patterns in this species. These data suggest, on a preliminary basis, that the acoustic structure of calls might be used as a bioacoustic tool for tracking individuals, dispersal, and other population dynamics in Belding's ground squirrels, and perhaps other vocal species.

  10. [Seasonal peculiarities of the ground squirrel (Spermophilus undulatus) and Wistar rats circadian activity].

    PubMed

    Semenova, T P; Spiridonova, L A; Zakharova, N M

    2014-09-01

    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 active period in rats was longer than in ground squirrels. It included not only at night, but morning time in spring, and daytime--in summer. The circadian differences between hibernators and non-hibernators were kept during all annual cycle at night time, but in daytime--only in spring and summer time.

  11. Seasonal Shedding of Multiple Cryptosporidium Genotypes in California Ground Squirrels (Spermophilus beecheyi)

    PubMed Central

    Atwill, Edward R.; Phillips, Ralph; Pereira, Maria Das Graças C.; Li, Xunde; McCowan, Brenda

    2004-01-01

    Twelve percent of 853 California ground squirrels (Spermophilus beecheyi) from six different geographic locations in Kern County, Calif., were found to be shedding on average 44,482 oocysts g of feces−1. The mean annual environmental loading rate of Cryptosporidium oocysts was 57,882 oocysts squirrel−1 day−1, with seasonal patterns of fecal shedding ranging from <10,000 oocysts squirrel−1 day−1 in fall, winter, and spring to levels of 2 × 105 oocysts squirrel−1 day−1 in summer. Juveniles were about twice as likely as adult squirrels to be infected and shed higher concentrations of oocysts than adults did, with particularly high levels of infection and shedding being found among juvenile male squirrels. Based on DNA sequencing of a portion of the 18S small-subunit rRNA gene, there existed three genotypes of Cryptosporidium species in these populations of squirrels (Sbey03a, Sbey03b, and Sbey03c; accession numbers AY462231 to AY462233, respectively). These unique DNA sequences were most closely related (96 to 97% homology) to porcine C. parvum (AF115377) and C. wrairi (AF115378). Inoculating BALB/c neonatal mice with up to 10,000 Sbey03b or Sbey03c fresh oocysts from different infected hosts did not produce detectable levels of infection, suggesting that this common genotype shed by California ground squirrels is not infectious for mice and may constitute a new species of Cryptosporidium. PMID:15528541

  12. Opposing activity changes in AMP deaminase and AMP-activated protein kinase in the hibernating ground squirrel.

    PubMed

    Lanaspa, Miguel A; Epperson, L Elaine; Li, Nanxing; Cicerchi, Christina; Garcia, Gabriela E; Roncal-Jimenez, Carlos A; Trostel, Jessica; Jain, Swati; Mant, Colin T; Rivard, Christopher J; Ishimoto, Takuji; Shimada, Michiko; Sanchez-Lozada, Laura Gabriela; Nakagawa, Takahiko; Jani, Alkesh; Stenvinkel, Peter; Martin, Sandra L; Johnson, Richard J

    2015-01-01

    Hibernating animals develop fatty liver when active in summertime and undergo a switch to a fat oxidation state in the winter. We hypothesized that this switch might be determined by AMP and the dominance of opposing effects: metabolism through AMP deaminase (AMPD2) (summer) and activation of AMP-activated protein kinase (AMPK) (winter). Liver samples were obtained from 13-lined ground squirrels at different times during the year, including summer and multiples stages of winter hibernation, and fat synthesis and β-fatty acid oxidation were evaluated. Changes in fat metabolism were correlated with changes in AMPD2 activity and intrahepatic uric acid (downstream product of AMPD2), as well as changes in AMPK and intrahepatic β-hydroxybutyrate (a marker of fat oxidation). Hepatic fat accumulation occurred during the summer with relatively increased enzymes associated with fat synthesis (FAS, ACL and ACC) and decreased enoyl CoA hydratase (ECH1) and carnitine palmitoyltransferase 1A (CPT1A), rate limiting enzymes of fat oxidation. In summer, AMPD2 activity and intrahepatic uric acid levels were high and hepatic AMPK activity was low. In contrast, the active phosphorylated form of AMPK and β-hydroxybutyrate both increased during winter hibernation. Therefore, changes in AMPD2 and AMPK activity were paralleled with changes in fat synthesis and fat oxidation rates during the summer-winter cycle. These data illuminate the opposing forces of metabolism of AMP by AMPD2 and its availability to activate AMPK as a switch that governs fat metabolism in the liver of hibernating ground squirrel.

  13. Molecular epidemiology of Bartonella species isolated from ground squirrels and other rodents in northern California.

    PubMed

    Ziedins, A C; Chomel, B B; Kasten, R W; Kjemtrup, A M; Chang, C-C

    2016-07-01

    Bartonella spp. are endemic in wild rodents in many parts of the world. A study conducted in two northern California counties (Sonoma and Yolo) sampling California ground squirrels (Otospermophilus beecheyi) and four other rodent species (Peromyscus maniculatus, P. boylii, P. truei and Neotoma fuscipes) led to the isolation of small Gram-negative bacilli which were identified as Bartonella spp. based on colony morphology, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and partial gene sequencing. Overall, Bartonella spp. were isolated from the blood of 71% (32/45) of the ground squirrels and one third (22/66) of the other rodents. PCR-RFLP analysis of the gltA and 16S rRNA genes yielded seven unique profiles, four for the ground squirrels and three for the other rodents. Isolates from each PCR-RFLP profiles were submitted for partial sequencing. Ground squirrel isolates were most closely related to B. washoensis, whereas the other rodent isolates were closest to B. vinsonii subsp. vinsonii and B. vinsonii subsp. arupensis. Two of these three species or subspecies are known zoonotic agents.

  14. Implications of Hybridization, NUMTs, and Overlooked Diversity for DNA Barcoding of Eurasian Ground Squirrels

    PubMed Central

    Ermakov, Oleg A.; Simonov, Evgeniy; Surin, Vadim L.; Titov, Sergey V.; Brandler, Oleg V.; Ivanova, Natalia V.; Borisenko, Alex V.

    2015-01-01

    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 obtained for 97 individuals representing 16 ground squirrel species of which 12 were correctly identified. Taxonomic allocation of some specimens within four species was complicated by geographically restricted mtDNA introgression. Exclusion of individuals with introgressed mtDNA allowed reaching a 91.6% identification success rate. Significant COI divergence (3.5–4.4%) was observed within the most widespread ground squirrel species (Spermophilus erythrogenys, S. pygmaeus, S. suslicus, Urocitellus undulatus), suggesting the presence of cryptic species. A single putative NUMT (nuclear mitochondrial pseudogene) sequence was recovered during molecular analysis; mitochondrial COI from this sample was amplified following re-extraction of DNA. Our data show high discrimination ability of 100 bp COI fragments for Eurasian ground squirrels (84.3%) with no incorrect assessments, underscoring the potential utility of the existing reference librariy for the development of diagnostic ‘mini-barcodes’. PMID:25617768

  15. Behavioural correlates of urbanisation in the Cape ground squirrel Xerus inauris.

    PubMed

    Chapman, Tarryn; Rymer, Tasmin; Pillay, Neville

    2012-11-01

    Urbanisation critically threatens biodiversity because of habitat destruction and novel selection pressures. Some animals can respond to these challenges by modifying their behaviour, particularly anti-predator behaviour, allowing them to persist in heavily transformed urban areas. We investigated whether the anti-predator behaviour of the Cape ground squirrel Xerus inauris differed in three localities that differed in their level of urbanisation. According to the habituation hypothesis, we predicted that ground squirrels in urban areas would: (a) be less vigilant and forage more; (b) trade-off flight/vigilance in favour of foraging; and (c) have shorter flight initiation distances (FID) when approached by a human observer. Observations were made in winter and summer at each locality. As expected, ground squirrels in urbanised areas were less vigilant and had shorter FIDs but did not trade-off between foraging and vigilance. In contrast, a population in a non-urbanised locality showed greater levels of vigilance, FID and traded-off vigilance and foraging. A population in a peri-urban locality showed mixed responses. Our results indicate that Cape ground squirrels reduce their anti-predator behaviour in urban areas and demonstrate a flexible behavioural response to urbanisation.

  16. Experimental Infection of Richardson's Ground Squirrels (Spermophilus richardsonii) with Attenuated and Virulent Strains of Brucella abortus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exposure of non-target species to wildlife vaccines is an important concern when evaluating a candidate vaccine for use in the field. A previous investigation of the safety of Brucella abortus strain RB51 (sRB51) in various non-target species suggested that Richardson’s ground squirrels (Spermophil...

  17. Implications of hybridization, NUMTs, and overlooked diversity for DNA Barcoding of Eurasian ground squirrels.

    PubMed

    Ermakov, Oleg A; Simonov, Evgeniy; Surin, Vadim L; Titov, Sergey V; Brandler, Oleg V; Ivanova, Natalia V; Borisenko, Alex V

    2015-01-01

    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 obtained for 97 individuals representing 16 ground squirrel species of which 12 were correctly identified. Taxonomic allocation of some specimens within four species was complicated by geographically restricted mtDNA introgression. Exclusion of individuals with introgressed mtDNA allowed reaching a 91.6% identification success rate. Significant COI divergence (3.5-4.4%) was observed within the most widespread ground squirrel species (Spermophilus erythrogenys, S. pygmaeus, S. suslicus, Urocitellus undulatus), suggesting the presence of cryptic species. A single putative NUMT (nuclear mitochondrial pseudogene) sequence was recovered during molecular analysis; mitochondrial COI from this sample was amplified following re-extraction of DNA. Our data show high discrimination ability of 100 bp COI fragments for Eurasian ground squirrels (84.3%) with no incorrect assessments, underscoring the potential utility of the existing reference librariy for the development of diagnostic 'mini-barcodes'.

  18. Behavioural correlates of urbanisation in the Cape ground squirrel Xerus inauris

    NASA Astrophysics Data System (ADS)

    Chapman, Tarryn; Rymer, Tasmin; Pillay, Neville

    2012-11-01

    Urbanisation critically threatens biodiversity because of habitat destruction and novel selection pressures. Some animals can respond to these challenges by modifying their behaviour, particularly anti-predator behaviour, allowing them to persist in heavily transformed urban areas. We investigated whether the anti-predator behaviour of the Cape ground squirrel Xerus inauris differed in three localities that differed in their level of urbanisation. According to the habituation hypothesis, we predicted that ground squirrels in urban areas would: (a) be less vigilant and forage more; (b) trade-off flight/vigilance in favour of foraging; and (c) have shorter flight initiation distances (FID) when approached by a human observer. Observations were made in winter and summer at each locality. As expected, ground squirrels in urbanised areas were less vigilant and had shorter FIDs but did not trade-off between foraging and vigilance. In contrast, a population in a non-urbanised locality showed greater levels of vigilance, FID and traded-off vigilance and foraging. A population in a peri-urban locality showed mixed responses. Our results indicate that Cape ground squirrels reduce their anti-predator behaviour in urban areas and demonstrate a flexible behavioural response to urbanisation.

  19. Managing anabolic steroids in pre-hibernating Arctic ground squirrels: obtaining their benefits and avoiding their costs

    PubMed Central

    Boonstra, Rudy; Mo, Kaiguo; Monks, Douglas Ashley

    2014-01-01

    Androgens have benefits, such as promoting muscle growth, but also significant costs, including suppression of immune function. In many species, these trade-offs in androgen action are reflected in regulated androgen production, which is typically highest only in reproductive males. However, all non-reproductive Arctic ground squirrels, irrespective of age and sex, have high levels of androgens prior to hibernating at sub-zero temperatures. Androgens appear to be required to make muscle in summer, which, together with lipid, is then catabolized during overwinter. By contrast, most hibernating mammals catabolize only lipid. We tested the hypothesis that androgen action is selectively enhanced in Arctic ground squirrel muscle because of an upregulation of androgen receptors (ARs). Using Western blot analysis, we found that Arctic ground squirrels have AR in skeletal muscle more than four times that of Columbian ground squirrels, a related southern species that overwinters at approximately 0°C and has low pre-hibernation androgen levels. By contrast, AR in lymph nodes was equivalent in both species. Brain AR was also modestly but significantly increased in Arctic ground squirrel relative to Columbian ground squirrel. These results are consistent with the hypothesis that tissue-specific AR regulation prior to hibernation provides a mechanism whereby Arctic ground squirrels obtain the life-history benefits and mitigate the costs associated with high androgen production. PMID:25376801

  20. Managing anabolic steroids in pre-hibernating Arctic ground squirrels: obtaining their benefits and avoiding their costs.

    PubMed

    Boonstra, Rudy; Mo, Kaiguo; Monks, Douglas Ashley

    2014-11-01

    Androgens have benefits, such as promoting muscle growth, but also significant costs, including suppression of immune function. In many species, these trade-offs in androgen action are reflected in regulated androgen production, which is typically highest only in reproductive males. However, all non-reproductive Arctic ground squirrels, irrespective of age and sex, have high levels of androgens prior to hibernating at sub-zero temperatures. Androgens appear to be required to make muscle in summer, which, together with lipid, is then catabolized during overwinter. By contrast, most hibernating mammals catabolize only lipid. We tested the hypothesis that androgen action is selectively enhanced in Arctic ground squirrel muscle because of an upregulation of androgen receptors (ARs). Using Western blot analysis, we found that Arctic ground squirrels have AR in skeletal muscle more than four times that of Columbian ground squirrels, a related southern species that overwinters at approximately 0°C and has low pre-hibernation androgen levels. By contrast, AR in lymph nodes was equivalent in both species. Brain AR was also modestly but significantly increased in Arctic ground squirrel relative to Columbian ground squirrel. These results are consistent with the hypothesis that tissue-specific AR regulation prior to hibernation provides a mechanism whereby Arctic ground squirrels obtain the life-history benefits and mitigate the costs associated with high androgen production.

  1. [Comparative analysis of Ca(2+)-signalling in brown preadipocytes of ground squirrel Spermophillus undulatus and mouse].

    PubMed

    Dolgacheva, L P; Konakov, M V; Agafonova, T A; Rybina, V V; Zinchenko, V P; Bronnikov, G E

    2007-01-01

    Analysis of the slow Ca(2+)-responses of brown preadipocytes of ground squirrel Spermophillus undulatus and mouse was carried out. The mouse brown preadipocytes demonstrated low but prominent responses to noradrenalin with the maximum at 3 and 10 microM being the less effective. The ground squirrel brown preadipocytes practically did not practically respond to 10 nM-10 microM, whereas 30-600 microM noradrenalin was able to raise intracellular [Ca2+]i up to 600 nM with 300 microM agonist being the most effective. Stimulation of the plasma membrane Ca(2+)-channels with thimerosal showed considerable reduction of the calcium entry system in the cell precursors of both species comparing with their mature adipocytes. Intracellular calcium stores liberated in preadipocytes of both species by tapsigargin and ionomycin in Ca(2+)-free medium were insignificant, and capacitative Ca(2+)-entry in response to the cellular Ca(2+)-stores depletion was completely absent in Ca(2+)-containing medium. The Ca(2+)-responses of the ground squirrel brown preadipocytes were independent on physiological state of the animals and annual seasons. Preadipocytes of both species showed the same dose-response curves for the Ca(2+)-raise under thimerosal, and the mouse had two-fold higher kinetic constants for the Ca2+ ions entry. The ground squirrel brown adipocytes responded to ionomycin with approximately 25% higher increase in [Ca2+]i and the entry of the ions had 7-10-fold higher kinetic constants for this process. Kinetic constants for the [Ca2+]i raise in mouse preadipocytes were independent of ionomycin concentration, whereas in the ground squirrel brown preadipocytes the constant linearly increased with the ionophore concentration. It is suggested that the found difference in the function of Ca(2+)-signalling in preadipocytes of two species, which becomes apparent in the presence of ionomycin, might be responsible for the observed difference in the noradrenalin induced cellular Ca(2

  2. Temperature adaptation of active sodium-potassium transport and of passive permeability in erythrocytes of ground squirrels.

    NASA Technical Reports Server (NTRS)

    Kimzey, S. L.; Willis, J. S.

    1971-01-01

    Unidirectional active and passive fluxes of K-42 and Na-24 were measured in red blood cells of ground squirrels (hibernators) and guinea pigs (nonhibernators). As the temperature was lowered, ?active' (ouabain-sensitive) K influx and Na efflux were more considerably diminished in guinea pig cells than in those of ground squirrels. The fraction of total K influx which is ouabain-sensitive in red blood cells of ground squirrels was virtually constant at all temperatures, whereas it decreased abruptly in guinea pig cells as temperature was lowered.

  3. Responses of three prairie ground squirrel species, Spermophilus franklinii, S. richardsonii, and S. tridecemlineatus, to duck eggs

    USGS Publications Warehouse

    Sargeant, A.B.; Sovada, M.A.; Greenwood, R.J.

    1987-01-01

    Franklin's Ground Squirrels (Spermophilus franklinii) preyed on eggs in 29 of 30 tests in which they were exposed to two Mallard (Anas platyrhynchos) or two Blue-winged Teal (A. discors) eggs and their discovery of eggs was confirmed. No Richardson's (S. richardsonii) or Thirteen-lined (S. tridecemlineatus) ground squirrels preyed on eggs in 104 and 54 similar tests, respectively. Franklin's Ground Squirrels exposed to clutches of six duck eggs placed in simulated nests preyed on all such clutches. Predation on simulated nests began soon after eggs were discovered, but predation of all eggs often took more than one day to complete.

  4. Consequences of artic ground squirrels on soil carbon loss from Siberian tundra

    NASA Astrophysics Data System (ADS)

    Golden, N. A.; Natali, S.; Zimov, N.

    2014-12-01

    A large pool of organic carbon (C) has been accumulating in the Arctic for thousands of years. Much of this C has been frozen in permafrost and unavailable for microbial decomposition. As the climate warms and permafrost thaws, the fate of this large C pool will be driven not only by climatic conditions, but also by ecosystem changes brought about by arctic animal populations. In this project we studied arctic ground squirrels (Spermophilus parryii), which are widely-distributed throughout the Arctic. These social mammals create subterranean burrows that mix soil layers, increase aeration, alter soil moisture and temperature, and redistribute soil nutrients, all of which may impact microbial decomposition. We examined the effects of arctic ground squirrel activity on soil C mineralization in dry heath tundra underlain by continuous permafrost in the Kolyma River watershed in northeast Siberia, Russia. Vegetation cover was greatly reduced on the ground squirrel burrows (80% of ground un-vegetated), compared to undisturbed sites (35% of ground un-vegetated). Soils from ground squirrel burrows were also significantly dryer and warmer. To examine effects of ground squirrel activity on microbial respiration, we conducted an 8-day incubation of soil fromburrows and from adjacent undisturbed tundra. In addition, we assessed the impact of nutrient addition by including treatments with low and high levels of nitrogen addition. Microbial respiration (per gram soil) was three-fold higher in incubated soils from the undisturbed sites compared to soils collected from the burrows. The lower rates of respiration from the disturbed soils may have been a result of lower carbon quality or low soil moisture. High nitrogen addition significantly increased respiration in the undisturbed soils, but not in the disturbed burrow soils, which suggests that microbial respiration in the burrow soils was not primarily limited by nitrogen. These results demonstrate the importance of wildlife

  5. HEAVY METAL, ORGANOCHLORINE PESTICIDE AND POLYCHLORINATED BIPHENYL CONTAMINATION IN ARCTIC GROUND SQUIRRELS (SPERMOPHILUS PARRYI) IN NORTHERN ALASKA

    EPA Science Inventory

    Heavy metal and organochlorine (OC)concentrations, including organochlorine pesticides and polychlorinated biphenyl congeners (PCBs), were determined in arctic ground squirrels (Spermophilus parryi) from three sites in the Brooks Range of northern Alaska in 1991-93. Heavy metals ...

  6. Evidence for a single class of somatostatin receptors in ground squirrel cerebral cortex

    SciTech Connect

    Krantic, S.; Petrovic, V.M.; Quirion, R.; Kordon, C.

    1989-01-01

    In the present study we characterized high-affinity somatostatin (SRIF) binding sites (Kd = 2.06 +/- 0.32 nM and Bmax = 295 +/- 28 fmol/mg protein) in cerebral cortex membrane preparations of European ground squirrel using /sup 125/I-(Tyr0-D-Trp8)-SRIF14 as a radioligand. The inhibition of radioligand specific binding by SRIF14, as well as by its agonists (SRIF28, Tyr0-D-Trp8-SRIF14, SMS 201 995) was complete and monophasic, thus revealing a single population of somatostatinergic binding sites. Radioautographic analysis of /sup 125/I-(Tyr0-D-Trp8)-SRIF14 labeled brain sections confirmed the results of our biochemical study. The homogeneity of SRIF binding sites in the ground squirrel neocortex was not dependent on the animal's life-cycle phase.

  7. Suspension of mitotic activity in dentate gyrus of the hibernating ground squirrel.

    PubMed

    Popov, Victor I; Kraev, Igor V; Ignat'ev, Dmitri A; Stewart, Michael G

    2011-01-01

    Neurogenesis occurs in the adult mammalian hippocampus, a region of the brain important for learning and memory. Hibernation in Siberian ground squirrels provides a natural model to study mitosis as the rapid fall in body temperature in 24 h (from 35-36°C to +4-6°C) permits accumulation of mitotic cells at different stages of the cell cycle. Histological methods used to study adult neurogenesis are limited largely to fixed tissue, and the mitotic state elucidated depends on the specific phase of mitosis at the time of day. However, using an immunohistochemical study of doublecortin (DCX) and BrdU-labelled neurons, we demonstrate that the dentate gyrus of the ground squirrel hippocampus contains a population of immature cells which appear to possess mitotic activity. Our data suggest that doublecortin-labelled immature cells exist in a mitotic state and may represent a renewable pool for generation of new neurons within the dentate gyrus.

  8. Cardiovascular function in large to small hibernators: bears to ground squirrels.

    PubMed

    Nelson, O Lynne; Robbins, Charles T

    2015-04-01

    Mammalian hibernation has intrigued scientists due to extreme variations in normal seasonal physiological homeostasis. Numerous species manifest a hibernation phenotype although the characteristics of the hypometabolic state can be quite different. Ground squirrels (e.g., Sciuridae) are often considered the prototypical hibernator as individuals in this genus transition from an active, euthermic state (37 °C) to a nonresponsive hibernating state where torpid body temperature commonly falls to 3-5 °C. However, the hibernating state is not continuous as periodic warming and arousals occur. In contrast, the larger hibernators of genus Ursus are less hypothermic (body temperatures decline from approximately 37°-33 °C), are more reactive, and cyclical arousals do not occur. Both species dramatically reduce cardiac output during hibernation from the active state (bears ~75 % reduction in bears and ~97 % reduction in ground squirrels), and both species demonstrate hypokinetic atrial chamber activity. However, there are several important differences in cardiac function between the two groups during hibernation. Left ventricular diastolic filling volumes and stroke volumes do not differ in bears between seasons, but increased diastolic and stroke volumes during hibernation are important contributors to cardiac output in ground squirrels. Decreased cardiac muscle mass and increased ventricular stiffness have been found in bears, whereas ground squirrels have increased cardiac muscle mass and decreased ventricular stiffness during hibernation. Molecular pathways of cardiac muscle plasticity reveal differences between the species in the modification of sarcomeric proteins such as titin and α myosin heavy chain during hibernation. The differences in hibernation character are likely to account for the alternative cardiac phenotypes and functional strategies manifested by the two species. Molecular investigation coupled with better knowledge of seasonal physiological

  9. No evidence for proteolytic venom resistance in southern African ground squirrels.

    PubMed

    Phillips, Molly A; Waterman, Jane M; Du Plessis, Pg; Smit, Martin; Bennett, Nigel C

    2012-10-01

    Many mammalian species that interact with venomous snakes show resistances to venoms. The family Sciuridae has several North American members that harass venomous snakes and show proteolytic resistances in their sera. We examined sera collected from an African ground squirrel (Xerus inauris) against two sympatric venomous snakes (Bitis arietans and Naja annulifera) and found no support for proteolytic resistance. Our results add to our understanding of the risks in predator defense within the family Sciuridae.

  10. Genomic analysis of miRNAs in an extreme mammalian hibernator, the Arctic ground squirrel.

    PubMed

    Liu, Yuting; Hu, Wenchao; Wang, Haifang; Lu, Minghua; Shao, Chunxuan; Menzel, Corinna; Yan, Zheng; Li, Ying; Zhao, Sen; Khaitovich, Philipp; Liu, Mofang; Chen, Wei; Barnes, Brian M; Yan, Jun

    2010-09-01

    MicroRNAs (miRNAs) are 19- to 25-nucleotide-long small and noncoding RNAs now well-known for their regulatory roles in gene expression through posttranscriptional and translational controls. Mammalian hibernation is a physiological process involving profound changes in set-points for food consumption, body mass and growth, body temperature, and metabolic rate in which miRNAs may play important regulatory roles. In an initial study, we analyzed miRNAs in the liver of an extreme hibernating species, the Arctic ground squirrel (Spermophilus parryii), using massively parallel Illumina sequencing technology. We identified >200 ground squirrel miRNAs, including 18 novel miRNAs specific to ground squirrel and mir-506 that is fast evolving in the ground squirrel lineage. Comparing animals sampled after at least 8 days of continuous torpor (late torpid), within 5 h of a spontaneous arousal episode (early aroused), and 1-2 mo after hibernation had ended (nonhibernating), we identified differentially expressed miRNAs during hibernation, which are also compared with the results from two other miRNA profiling methods: Agilent miRNA microarray and real-time PCR. Among the most significant miRNAs, miR-320 and miR-378 were significantly underexpressed during both stages of hibernation compared with nonhibernating animals, whereas miR-486 and miR-451 were overexpressed in late torpor but returned in early arousal to the levels similar to those in nonhibernating animals. Analyses of their putative target genes suggest that these miRNAs could play an important role in suppressing tumor progression and cell growth during hibernation. High-throughput sequencing data and microarray data have been submitted to GEO database with accession: GSE19808.

  11. Kin effects on energy allocation in group-living ground squirrels.

    PubMed

    Viblanc, Vincent A; Saraux, Claire; Murie, Jan O; Dobson, F Stephen

    2016-09-01

    The social environment has potent effects on individual phenotype and fitness in group-living species. We asked whether the presence of kin might act on energy allocation, a central aspect of life-history variation. Using a 22-year data set on reproductive and somatic allocations in Columbian ground squirrels (Urocitellus columbianus), we tested the effects of co-breeding and non-breeding kin on the fitness and energy allocation balance between reproduction and personal body condition of individual females. Greater numbers of co-breeding kin had a positive effect on the number of offspring weaned, through the mechanism of altering energy allocation patterns. On average, females with higher numbers of co-breeding kin did not increase energy income but biased energy allocation towards reproduction. Co-breeding female kin ground squirrels maintain close nest burrows, likely providing a social buffer against territorial invasions from non-kin ground squirrels. Lower aggressiveness, lower risks of infanticide from female kin and greater protection of territorial boundaries may allow individual females to derive net fitness benefits via their energy allocation strategies. We demonstrated the importance of kin effects on a fundamental life-history trade-off.

  12. The ontogeny of kin-recognition mechanisms in Belding's ground squirrels.

    PubMed

    Mateo, Jill M

    2017-05-01

    Despite extensive research on the functions and mechanisms of kin recognition, little is known about developmental changes in the abilities mediating such recognition. Belding's ground squirrels, Urocitellus beldingi, use at least two mechanisms of kin recognition in nepotistic contexts: familiarity and phenotype matching. Because recognition templates develop from early associations with familiar kin (and/or with self), familiarity-based recognition should precede phenotype-matching recognition even though one template is thought to be used for both mechanisms. I used a cross-fostering design to produce individuals that differed in relatedness and familiarity. Two pups (one female and one male) were exchanged reciprocally between two litters within 48-h of birth. Every five days, from 15 to 30-d of age, young were exposed to bedding and oral-gland odors from their familiar foster mother and an unfamiliar unrelated female (familiarity test) and from their unfamiliar genetic mother and another unfamiliar unrelated female (phenotype-matching test). As expected, discrimination of odors based on familiarity was evident at all ages tested, whereas discrimination based on relatedness was not evident until 30-d. My results provide a first estimate for when phenotype-matching mechanisms are used by young Belding's ground squirrels, and thus when they can recognize unfamiliar kin such as older sisters or grandmothers. Belding's ground squirrels are the first species for which the development of the production, perception and action components is well understood.

  13. Seasonal changes in immunoreactivity of activin signaling component proteins in wild ground squirrel testes.

    PubMed

    Sheng, Xia; Zhang, Haolin; Zhang, Mengyuan; Zhang, Wei; Hu, Xiao; Song, Moshi; Zhou, Jiao; Xu, Meiyu; Weng, Qiang; Watanabe, Gen; Taya, Kazuyoshi

    2012-01-01

    The seasonal spermatogenesis and localization of inhibin/activin subunits (alpha, betaA, betaB) in the testes of wild ground squirrel has been previously described; however, the expression pattern of activin receptors and cytoplasmic signaling SMADs has not been detected in any seasonal breeders. The objective of this study was to investigate the abundance and cellular localization of activin signaling components in testes of the wild ground squirrel during the breeding and nonbreeding seasons. The immunolocalizations of ActRIIB (activin type II receptor B) and activin-related SMADs (phospho-SMAD2/3, SMAD4 and SMAD7) were observed by immunohistochemistry. Total proteins were extracted from testicular tissues in the breeding and nonbreeding seasons and were used for Western blotting analysis for ActRIIB and SMADs. Immunoreactivities of activin signaling components were greater in the testes of the breeding season, and then decreased to a relatively low level in the nonbreeding season. ActRIIB and related SMADs were widely spread in the active testes, while spermatogonia were the predominant cellular sites of activin signal transduction during arrested spermatogenesis. The dynamic regulation of activin type II receptor and SMADs indicated that the activin signal pathway played an important paracrine role in seasonal spermatogenesis of the wild ground squirrel. Furthermore, the distinct localizations and immunoreactivity of ActRIIB and SMADs might suggest different functions of activin in seasonal spermatogenesis.

  14. Seasonal patterns of body temperature daily rhythms in group-living Cape ground squirrels Xerus inauris.

    PubMed

    Scantlebury, Michael; Danek-Gontard, Marine; Bateman, Philip W; Bennett, Nigel C; Manjerovic, Mary Beth; Manjerovic, Mary-Beth; Joubert, Kenneth E; Waterman, Jane M

    2012-01-01

    Organisms respond to cyclical environmental conditions by entraining their endogenous biological rhythms. Such physiological responses are expected to be substantial for species inhabiting arid environments which incur large variations in daily and seasonal ambient temperature (T(a)). We measured core body temperature (T(b)) daily rhythms of Cape ground squirrels Xerus inauris inhabiting an area of Kalahari grassland for six months from the Austral winter through to the summer. Squirrels inhabited two different areas: an exposed flood plain and a nearby wooded, shady area, and occurred in different social group sizes, defined by the number of individuals that shared a sleeping burrow. Of a suite of environmental variables measured, maximal daily T(a) provided the greatest explanatory power for mean T(b) whereas sunrise had greatest power for T(b) acrophase. There were significant changes in mean T(b) and T(b) acrophase over time with mean T(b) increasing and T(b) acrophase becoming earlier as the season progressed. Squirrels also emerged from their burrows earlier and returned to them later over the measurement period. Greater increases in T(b), sometimes in excess of 5°C, were noted during the first hour post emergence, after which T(b) remained relatively constant. This is consistent with observations that squirrels entered their burrows during the day to 'offload' heat. In addition, greater T(b) amplitude values were noted in individuals inhabiting the flood plain compared with the woodland suggesting that squirrels dealt with increased environmental variability by attempting to reduce their T(a)-T(b) gradient. Finally, there were significant effects of age and group size on T(b) with a lower and less variable T(b) in younger individuals and those from larger group sizes. These data indicate that Cape ground squirrels have a labile T(b) which is sensitive to a number of abiotic and biotic factors and which enables them to be active in a harsh and variable

  15. Seasonal restructuring of the ground squirrel gut microbiota over the annual hibernation cycle.

    PubMed

    Carey, Hannah V; Walters, William A; Knight, Rob

    2013-01-01

    Many hibernating mammals suspend food intake during winter, relying solely on stored lipids to fuel metabolism. Winter fasting in these species eliminates a major source of degradable substrates to support growth of gut microbes, which may affect microbial community structure and host-microbial interactions. We explored the effect of the annual hibernation cycle on gut microbiotas using deep sequencing of 16S rRNA genes from ground squirrel cecal contents. Squirrel microbiotas were dominated by members of the phyla Bacteroidetes, Firmicutes, and Verrucomicrobia. UniFrac analysis showed that microbiotas clustered strongly by season, and maternal influences, diet history, host age, and host body temperature had minimal effects. Phylogenetic diversity and numbers of operational taxonomic units were lowest in late winter and highest in the spring after a 2-wk period of refeeding. Hibernation increased relative abundance of Bacteroidetes and Verrucomicrobia, phyla that contain species capable of surviving on host-derived substrates such as mucins, and reduced relative abundance of Firmicutes, many of which prefer dietary polysaccharides. Hibernation reduced cecal short-chain fatty acid and ammonia concentrations, and increased and decreased concentrations of acetate and butyrate, respectively. These results indicate that the ground squirrel microbiota is restructured each year in a manner that reflects differences in microbial preferences for dietary vs. host-derived substrates, and thus the competitive abilities of different taxa to survive in the altered environment in the hibernator gut.

  16. Delayed effect of pinealectomy on hibernation of the golden-mantled ground squirrel

    NASA Astrophysics Data System (ADS)

    Ralph, C. L.; Harlow, H. J.; Phillips, J. A.

    1982-12-01

    Pinealectomy or radical sham pinealectomy were performed on adult golden-mantled ground squirrels, Spermophilus (=Citellus) lateralis, approximately 1 month prior to the date of normal winter emergence. The first hibernatory period and subsequent active season were not different in either of the operated groups from intact animals. However, although the initiation of the second hibernatory period was not affected in the pinealectomized animals, this group failed to show the progressive increase in the length of heterothermic bouts that is characteristic of normal hibernation. Also, terminal arousal occurred approximately 6 weeks earlier in the second year after pinealectomy. Male squirrels showed a corresponding time compression in their annual gonadal cycle, as was assessed by testicular state. These results suggest that the pineal gland of the golden-mantled ground squirrel is involved in the expression of the annual hibernatory cycle. In the absence of the pineal gland the adult of this species is unable to sustain the normal depth and duration of hibernation in the second over-wintering period following pinealectomy. We have carried out additional experiments with young, laboratory-born S. lateralis and with field-caught, adult S. richardsonii. The results of these studies also are described in this paper.

  17. Demographic features of Bartonella infections in Richardson's ground squirrels (Spermophilus richardsonii).

    PubMed

    Jardine, C; Waldner, C; Wobeser, G; Leighton, F A

    2006-10-01

    The epidemiology of Bartonella infections in Richardson's ground squirrels (Spermophilus richardsonii) was studied at multiple sites in Saskatchewan, Canada, from 2002 to 2004. The overall prevalence of Bartonella infection was 48%. Juvenile squirrels were significantly more likely to be infected with Bartonella than were adults (58% and 37%, respectively), and juvenile animals also were significantly more likely to have high levels of bacteremia compared to adult animals. Prevalence of Bartonella infection appeared to decrease with age; only 24% of animals known to be > or = 2 yr old were infected with Bartonella. Prevalence of infection was lowest in May (27%) and highest in late summer and early autumn (71%). The prevalence of fleas also varied seasonally, and animals were more likely to have fleas in the late summer and early autumn than in early summer. We found no relationship between Bartonella prevalence and host density or flea prevalence.

  18. [Influence of ADP-ribose, AMP and adenosine on bioelectric activity of hibernating ground squirrel atrium and papillary muscle].

    PubMed

    Kuz'min, V S; Abramochkin, D V; Sukhova, G S; Rozenshtraukh, L V

    2008-01-01

    The aim of work was to investigate effects of adenosine, AMP and ADP-ribose (1x10(-5)) on bioelectric activity of atrium and papillary muscle of nonhibernating (rat) and hibernating (Yakutian ground squirrel) animals. Action potential (AP) was registered with use of standard microelectrode technique. AP duration (APD) at level of 90% repolarisation in rat atrium in control experiments was 30+/-5 ms, APD at level of 50% repolarisation was 12+/-2 ms. APD at level of 90% repolarisation in rat papillary muscle was 56+/-7 ms, at level of 50% repolarisation was 18+/-2 ms. APD at level of 90% repolarisation in ground squirrel atrium was 77+/-6, APD at level of 50% repolarisation was 38+/-6 ms. APD at level of 90% repolarisation in ground squirrel papillary muscle was 105+/-9 ms, APD at level of 50% repolarisation was 42+/-8 ms. Purine nucleotides and nucleoside, that were tested in work, except ADP-ribose, act as inhibitory factors and decrease APD both in rat and hibernating ground squirrel heart. ADP-ribose decreases APD in papillary muscle of hibernator but did not in its atrium. In ground squirrel atrium AMP and adenosine decrease APD at level of 50% repolarisation by 10+/-3% and 18+/-3% respectively. AMP and adenosine decrease APD at level of 90% repolarisation by 9+/-2% and 11+/-2% respectively. In ground squirrel papillary muscle ADP-ribose, AMP and adenosine decrease APD at level of 50% repolarisation by 26+/-8%, 23+/-8% and 26+/-7%. ADP-ribose, AMP and adenosine decrease APD at level of 90% repolarisation by 12+/-3%, 10+/-3%, 13+/-3%. Thus, decrease of APD in ground squirrel papillary muscle at level of 90% repolarisation during nucleotides and adenosine action was 2-2.5 fold less, than the rat.

  19. Leptin regulates energy intake but fails to facilitate hibernation in fattening Daurian ground squirrels (Spermophilus dauricus).

    PubMed

    Xing, Xin; Tang, Gang-Bin; Sun, Ming-Yue; Yu, Chao; Song, Shi-Yi; Liu, Xin-Yu; Yang, Ming; Wang, De-Hua

    2016-04-01

    Body fat storage before hibernation affects the timing of immergence in Daurian ground squirrels (Spermophilus dauricus). Leptin is an adipose signal and plays vital role in energy homeostasis mainly by action in brain. To test the hypothesis that leptin plays a role in facilitating the process of hibernation, squirrels were administrated with recombinant murine leptin (1μg/day) through intracerebroventricular (ICV) injection for 12 days during fattening. From day 7 to 12, animals were moved into a cold room (5±1°C) with constant darkness which functioned as hibernaculum. Energy intake, body mass and core body temperature (Tb) were continuously monitored throughout the course of experiment. Resting metabolic rate (RMR) was measured under both warm and cold conditions. At the end of leptin administration, we measured the serum concentration of hormones related to energy regulation, mRNA expression of hypothalamic neuropeptides and uncoupling protein 1 (UCP1) levels in brown adipose tissue (BAT). Our results showed that during leptin administration, the cumulative food intake and increase of body mass were suppressed while Tb and RMR were unaltered. The proportion of torpid squirrels was not different between two groups. At the end of leptin administration, the expressions of hypothalamic neuropeptide Y and agouti gene-related protein were suppressed. There were no differences in UCP1 mRNA expression or protein content in BAT between groups. Our data suggest that leptin can affect energy intake via hypothalamic neuropeptides, but is not involved in the initiation of hibernation in fattening Daurian ground squirrels.

  20. Thermoregulatory changes anticipate hibernation onset by 45 days: data from free-living arctic ground squirrels.

    PubMed

    Sheriff, Michael J; Williams, Cory T; Kenagy, G J; Buck, C Loren; Barnes, Brian M

    2012-08-01

    Hibernation is a strategy of reducing energy expenditure, body temperature (T(b)) and activity used by endotherms to escape unpredictable or seasonally reduced food availability. Despite extensive research on thermoregulatory adjustments during hibernation, less is known about transitions in thermoregulatory state, particularly under natural conditions. Laboratory studies on hibernating ground squirrels have demonstrated that thermoregulatory adjustments may occur over short intervals when animals undergo several brief, preliminary torpor bouts prior to entering multiday torpor. These short torpor bouts have been suggested to reflect a resetting of hypothalamic regions that control T(b) or to precondition animals before they undergo deep, multiday torpor. Here, we examined continuous records of T(b) in 240 arctic ground squirrels (Urocitellus parryii) prior to hibernation in the wild and in captivity. In free-living squirrels, T(b) began to decline 45 days prior to hibernation, and average T(b) had decreased 4.28 °C at the onset of torpor. Further, we found that 75 % of free-living squirrels and 35 % of captive squirrels entered bouts of multiday torpor with a single T(b) decline and without previously showing short preliminary bouts. This study provides evidence that adjustments in the thermoregulatory component of hibernation begin far earlier than previously demonstrated. The gradual reduction in T(b) is likely a component of the suite of metabolic and behavioral adjustments, controlled by an endogenous, circannual rhythm, that vary seasonally in hibernating ground squirrels.

  1. Ground squirrel tail-flag displays alter both predatory strike and ambush site selection behaviours of rattlesnakes.

    PubMed

    Barbour, Matthew A; Clark, Rulon W

    2012-09-22

    Many species approach, inspect and signal towards their predators. These behaviours are often interpreted as predator-deterrent signals--honest signals that indicate to a predator that continued hunting is likely to be futile. However, many of these putative predator-deterrent signals are given when no predator is present, and it remains unclear if and why such signals deter predators. We examined the effects of one such signal, the tail-flag display of California ground squirrels, which is frequently given both during and outside direct encounters with northern Pacific rattlesnakes. We video-recorded and quantified the ambush foraging responses of rattlesnakes to tail-flagging displays from ground squirrels. We found that tail-flagging deterred snakes from striking squirrels, most likely by advertising squirrel vigilance (i.e. readiness to dodge a snake strike). We also found that tail-flagging by adult squirrels increased the likelihood that snakes would leave their ambush site, apparently by elevating the vigilance of nearby squirrels which reduces the profitability of the ambush site. Our results provide some of the first empirical evidence of the mechanisms by which a prey display, although frequently given in the absence of a predator, may still deter predators during encounters.

  2. Melatonin receptor signaling contributes to neuroprotection upon arousal from torpor in thirteen-lined ground squirrels

    PubMed Central

    Schwartz, Christine; Ballinger, Mallory A.

    2015-01-01

    The brain of mammalian hibernators is naturally protected. Hibernating ground squirrels undergo rapid and extreme changes in body temperature and brain perfusion as they cycle between lengthy torpor bouts and brief periods of euthermia called interbout arousals (IBAs). Arousal from torpor to IBA occurs rapidly, but there is no evidence of brain injury accompanying this extreme physiological transition. Production of the hormone melatonin accompanies arousal, suggesting that it plays a protective role at this time. Here, we investigated mechanisms of melatonin receptor-mediated protection in the brain of the hibernating ground squirrel. We administered the competitive melatonin receptor antagonist luzindole (30 mg/kg ip) to ground squirrels at the predicted end of a torpor bout, triggering an arousal. We found that luzindole-treated animals exhibited caspase-3 activity two times higher than vehicle-treated animals in the hypothalamus at midarousal (P = 0.01), suggesting that melatonin receptor signaling is important for protection in this brain region. We also found a 30% decline in succinate-fueled mitochondrial respiration in luzindole-treated animals compared with vehicle-treated animals (P = 0.019), suggesting that melatonin receptor signaling is important for optimal mitochondrial function during arousal from torpor. The mitochondrial effects of luzindole treatment were seen only during the hibernation season, indicating that this effect is specifically important for arousal from torpor. These data provide evidence for the protective role of melatonin receptor signaling during the extreme physiological transition that occurs when a hibernating mammal arouses from torpor and provide further evidence for regional and seasonal changes in the hibernator brain. PMID:26354846

  3. [Effect of isoproterenol on contractility of the heart papillary muscles of a ground squirrel].

    PubMed

    Averin, A S; Zakharova, N M; Ignat'ev, D A; Tarlachkov, S V; Nakipova, O V

    2010-01-01

    The effect of isoproterenol (1 microM) on the force of isometric contractions (0.1-1.0 Hz, 30 +/- 1 degree C, 1.8 mM Ca2+) of papillary muscles of the right ventricle of the heart of the ground squirrel during summer activity (n = 5) and hibernation (activity between hibernation bouts, n = 4; torpor, n = 4; and arousal, n = 5) has been studied. It was shown that isoproterenol increases the force of contraction (positive inotropic effect) in active summer ground squirrels by 20 +/- 3 and 61 +/- 7% at stimulation frequencies of 0.4 and 1.0 Hz, respectively. The isoproterenol-induced increase in the force of contraction in animals during hibernation is brief (within 3 min after the onset of treatment) and this parameter decreases by 30-50% of the control level (negative inotropic effect) at stimulation frequencies from 0.3 and 0.8 Hz. The positive inotropic effect of isoproterenol in active summer ground squirrels is associated with a decrease in the relative value of the potentiating effect of the pause (qualitative indicator of calcium content in the sarcoplasmic reticulum), and the negative inotropic effect, with its increase. It was found that the inotropic effect of isoproterenol in all groups of animals examined (irrespective of its direction) is accompanied by an acceleration of the velocity of the contraction-relaxation cycle. The dependence of the effect of isoproterenol in the heart of hibernating animals on seasonal changes in the calcium homeostasis and the activity of the sympathetic nervous system is discussed.

  4. Fungal remains in Pleistocene ground squirrel dung from Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Pirozynski, Kris A.; Carter, Adrian; Day, Richard G.

    1984-11-01

    Fungi in dung of the Arctic ground squirrel ( Spermophilus parryii) collected near Dominion Creek, Yukon Territory, Canada, have a radiocarbon age of 12,200 ± 100 yr B.P. Most of the fungal remains are assignable to modern taxa, and most of these are either widespread saprobes or nonspecific coprophiles. However, specimens identified as Chaetomium simile and Thecaphora deformans represent fungi that may be more characteristic of rodent dung than that of other animals, inviting consideration of dung fungi as a potential source of paleontological data.

  5. You can hide but you can’t run: apparent competition, predator responses and the decline of Arctic ground squirrels in boreal forests of the southwest Yukon

    PubMed Central

    Gillis, Elizabeth A.; Boonstra, Rudy; Krebs, Charles J.

    2016-01-01

    Throughout much of North America’s boreal forest, the cyclical fluctuations of snowshoe hare populations (Lepus americanus) may cause other herbivores to become entrained in similar cycles. Alternating apparent competition via prey switching followed by positive indirect effects are the mechanisms behind this interaction. Our purpose is to document a change in the role of indirect interactions between sympatric populations of hares and arctic ground squirrels (Urocitellus parryii plesius), and to emphasize the influence of predation for controlling ground squirrel numbers. We used mark-recapture to estimate the population densities of both species over a 25-year period that covered two snowshoe hare cycles. We analysed the strength of association between snowshoe hare and ground squirrel numbers, and the changes to the seasonal and annual population growth rates of ground squirrels over time. A hyperbolic curve best describes the per capita rate of increase of ground squirrels relative to their population size, with a single stable equilibrium and a lower critical threshold below which populations drift to extinction. The crossing of this unstable boundary resulted in the subsequent uncoupling of ground squirrel and hare populations following the decline phase of their cycles in 1998. The implications are that this sustained Type II predator response led to the local extinction of ground squirrels. When few individuals are left in a colony, arctic ground squirrels may also have exhibited an Allee effect caused by the disruption of social signalling of approaching predators. PMID:27635312

  6. Antipredator vigilance of juvenile and adult thirteen-lined ground squirrels and the role of nutritional need.

    PubMed

    Arenz; Leger

    2000-03-01

    Juvenile thirteen-lined ground squirrels, Spermophilus tridecemlineatus, are less vigilant (i.e. they spend less time visually scanning the environment) than adults. To determine whether nutritional need was a potential cause of this difference, we supplemented two groups of free-ranging juveniles during the predispersal stage, while juveniles were still near and around the natal burrows. The high-energy food group (HEF: 11 squirrels) received peanut butter and oats while the low-energy food group (LEF: seven squirrels) received lettuce. Adults (14 squirrels) were also supplemented, but due to their greater home range sizes, it was not feasible to classify them as either HEF or LEF. To evaluate the effect of supplementation on antipredator vigilance, the behavioural act of visually scanning for predators, we videotaped individuals while they were foraging above ground during 5-min observation periods. Each squirrel was observed and weighed during three time periods over 23 days. From the videotape, we extracted measures of time spent vigilant, locomoting and foraging. All three categories of squirrels gained mass over the study period, but the HEF juveniles rapidly exceeded that of the LEF juveniles. Early in the study, LEF and HEF juveniles did not significantly differ in either body mass or time budgets, and, initially, both juvenile groups were similar to adults in the amount of time devoted to vigilance. Later in the study, the behaviour of HEF juveniles closely resembled that of adults (increased time devoted to vigilance and decreased time devoted to foraging), while LEF juveniles decreased vigilance and increased their foraging time. This study indicates that for thirteen-lined ground squirrels the lower vigilance of juveniles is due, at least in part, to the greater nutritional needs of young animals with consequent increases in foraging, which is largely incompatible with vigilance. Copyright 2000 The Association for the Study of Animal Behaviour.

  7. V1 connections reveal a series of elongated higher visual areas in the California ground squirrel, Otospermophilus beecheyi.

    PubMed

    Negwer, Moritz; Liu, Yong-Jun; Schubert, Dirk; Lyon, David C

    2017-06-01

    For studies of visual cortex organization, mouse is becoming an increasingly more often used model. In addition to its genetic tractability, the relatively small area of cortical surface devoted to visual processing simplifies efforts in relating the structure of visual cortex to visual function. However, the nature of this compact organization can make some comparisons to the much larger non-human primate visual cortex difficult. The squirrel, as a highly visual rodent offers a useful means for better understanding how mouse and monkey cortical organization compares. More in line with primates than their nocturnal rodent cousin, squirrels rely much more on sight and have evolved a larger expanse of cortex devoted to visual processing. To reveal the detailed organization of visual cortex in squirrels, we injected a highly sensitive monosynaptic retrograde tracer (glycoprotein deleted rabies virus) into several locations of primary visual cortex (V1) in California ground squirrels. The resulting pattern of connectivity revealed an organizational scheme in the squirrel that retains some of the basic features of the mouse visual cortex along the medial and posterior borders of V1, but unlike mouse has an elaborate and extensive pattern laterally that is more similar to the early visual cortex organization found in monkeys. In this way, we show that the squirrel can serve as a useful model for comparison to both mouse and primate visual systems, and may help facilitate comparisons between these two very different yet widely used animal models of visual processing.

  8. [Breeding success and direction of animal crossing in the hybrid russet (Spermophilus major) and yellow (Spermophilus fulvus) ground squirrel population].

    PubMed

    Shmyrov, A A; Kuz'min, A A; Kuz'min, A A; Titov, S V

    2011-01-01

    Reproductive relations between animals in the hybrid settlement of the russet and yellow ground squirrels are panmictic and are characterized by the absence of assortative crossings and by the presence of multimale pairings in females with evidently heterospermic broods. Maximum breeding success was observed for hybrid animals proving the fertility of hybrids. However, the hybrid breeding potential (young animal survival rate) is significantly lower as compared with russet and yellow ground squirrels, but the survival rate of the hybrid progeny in the hybrid population is not lower than in specific settlements.

  9. Acoustic analysis of the alarm call of the Anatolian ground squirrel Spermophilus xanthoprymnus: a description and comparison with alarm calls of the Taurus S. taurensis and European S. citellus ground squirrels

    NASA Astrophysics Data System (ADS)

    Schneiderová, Irena; Policht, Richard

    2012-01-01

    The Anatolian ground squirrel Spermophilus xanthoprymnus like other ground-dwelling sciurids, emits alarm calls in the presence of predators. In this study, we provide a description of the acoustic structure of alarm call of this species and compare it to those of two closely related species, the Taurus ground squirrel Spermophilus taurensis and the European ground squirrel Spermophilus citellus. The alarm call of S. xanthoprymnus is a tonal sound mostly consisting of two different elements—the first element has low frequency modulation while the second element is highly frequency modulated. A similar basic structure can be found in the alarm calls of some other old world ground squirrel species of the genus Spermophilus, including S. taurensis and S. citellus. Despite this similarity, we found that these three species can be clearly distinguished on the basis of their alarm calls. Differences in the acoustic structure of S. xanthoprymnus and S. taurensis calls are especially remarkable, as these two species were considered to be conspecific until 2007. S. xanthoprymnus and S. taurensis were also demonstrated to have closer acoustic similarity, which is in contrast to results based on molecular data indicating that S. taurensis is most closely related to S. citellus.

  10. Acoustic analysis of the alarm call of the Anatolian ground squirrel Spermophilus xanthoprymnus: a description and comparison with alarm calls of the Taurus S. taurensis and European S. citellus ground squirrels.

    PubMed

    Schneiderová, Irena; Policht, Richard

    2012-01-01

    The Anatolian ground squirrel Spermophilus xanthoprymnus like other ground-dwelling sciurids, emits alarm calls in the presence of predators. In this study, we provide a description of the acoustic structure of alarm call of this species and compare it to those of two closely related species, the Taurus ground squirrel Spermophilus taurensis and the European ground squirrel Spermophilus citellus. The alarm call of S. xanthoprymnus is a tonal sound mostly consisting of two different elements-the first element has low frequency modulation while the second element is highly frequency modulated. A similar basic structure can be found in the alarm calls of some other old world ground squirrel species of the genus Spermophilus, including S. taurensis and S. citellus. Despite this similarity, we found that these three species can be clearly distinguished on the basis of their alarm calls. Differences in the acoustic structure of S. xanthoprymnus and S. taurensis calls are especially remarkable, as these two species were considered to be conspecific until 2007. S. xanthoprymnus and S. taurensis were also demonstrated to have closer acoustic similarity, which is in contrast to results based on molecular data indicating that S. taurensis is most closely related to S. citellus.

  11. The influence of changing seasonality and snow cover on arctic ground squirrel phenology.

    NASA Astrophysics Data System (ADS)

    Barnes, B.; Sheriff, M.; Kenagy, J.; Buck, L.; Team Squirrel

    2011-12-01

    A warming climate in the Arctic may have asymmetrical effects on seasonality, depending on the timing and extent of snow cover. Warm autumns that delay the onset of persistent snow cover will lengthen growing seasons of some plants and, combined with continuing access to fallen seeds, berries, and leaves, extend feeding opportunities for ground foragers. Warming in spring should advance when the ground becomes snow free and the onset of plant productivity, leading overall to a longer growing season. However, if winter and spring precipitation increase, as is predicted in climate models, the amount and seasonal extent of snow pack will increase, which will delay melt and lead to delayed springs. Either of these scenarios may develop regionally, depending on local weather, snow, and wind. Since 1996, we have been investigating the timing of annual events in natural populations of arctic ground squirrels, Urocitellus parryii, living at two nearby sites (Toolik and Atigun, 68o38'N) in arctic Alaska that greatly differ in timing and duration of snow cover. Since arctic ground squirrels are highly dependent on snow free ground for foraging, we predicted that these environmental differences will have had major impacts on life histories and timing of annual events on the local populations. Precision in dates of the beginning and end of hibernation, use of heterothermy, and birth of young were determined by temperature-sensitive data loggers implanted into juvenile and adult animals of both sexes. Weather stations, snow cameras, and transects for plant phenology are in place at both locations, although record lengths differ. While across the past 15 years annual timing of hibernation and breeding has not shown significant trends at either site, the two populations have differed consistently in hibernation timing and length of active season, and they show a 13 day difference in average timing of reproduction. These results reveal a substantial flexibility of timing of the

  12. Differential regulation of uncoupling protein gene homologues in multiple tissues of hibernating ground squirrels.

    PubMed

    Boyer, B B; Barnes, B M; Lowell, B B; Grujic, D

    1998-10-01

    Nonshivering thermogenesis in brown adipose tissue (BAT) provides heat through activation of a mitochondrial uncoupling protein (UCP1), which causes futile electron transport cycles without the production of ATP. Recent discovery of two molecular homologues, UCP2, expressed in multiple tissues, and UCP3, expressed in muscle, has resulted in investigation of their roles in thermoregulatory physiology and energy balance. To determine the expression pattern of Ucp homologues in hibernating mammals, we compared relative mRNA levels of Ucp1, -2, and -3 in BAT, white adipose tissue (WAT), and skeletal muscle of arctic ground squirrels (Spermophilus parryii) hibernating at different ambient and body temperatures, with levels determined in tissues from ground squirrels not in hibernation. Here we report significant increases in mRNA levels for Ucp2 in WAT (1. 6-fold) and Ucp3 in skeletal muscle (3-fold) during hibernation. These results indicate the potential for a role of UCP2 and UCP3 in thermal homeostasis during hibernation and indicate that parallel mechanisms and multiple tissues could be important for nonshivering thermoregulation in mammals.

  13. Kin selection in Columbian ground squirrels: direct and indirect fitness benefits.

    PubMed

    Dobson, F Stephen; Viblanc, Vincent A; Arnaud, Coline M; Murie, Jan O

    2012-02-01

    Empirical and theoretical studies have supported kin selection by demonstrating nepotism or modelling its conditions and consequences. As an alternative, we previously found that female Columbian ground squirrels had greater direct fitness when more close kin were present. Extending those results, we used population matrix methods to calculate minimum estimates of individual fitness, estimated direct and indirect components of fitness, estimated inclusive fitness by adding the direct fitness (stripped of estimated influences of the social environment) and indirect fitness components together, and finally looked for inclusive fitness benefits of associations with close kin who seem to be 'genial neighbours'. We examined the estimated fitness of a sample of 35 females for which complete lifetimes were known for themselves, their mothers and their littermate sisters. Six of these females had no cosurviving adult close kin, and their direct fitness was significantly lower than 29 females with such kin (λ = 0.66 vs. λ = 1.23). The net fitness benefit of the presence of close kin was thus 0.57. The estimated indirect component of fitness through benefits to the direct fitness of close kin was 0.43. Thus, estimated inclusive fitness for females with cosurviving close kin (λ = 1.09) was significantly greater than that for females without surviving close kin (viz., λ = 0.66). The presence of closely related and philopatric female kin appeared to result in considerable fitness benefits for female ground squirrels, perhaps through the behavioural mechanisms of lowered aggression and other forms of behavioural cooperation.

  14. Caching in the presence of competitors: Are Cape ground squirrels (Xerus inauris) sensitive to audience attentiveness?

    PubMed

    Samson, Jamie; Manser, Marta B

    2016-01-01

    When social animals cache food close to their burrow, the potential for an audience member to observe the event is significantly increased. As a consequence, in order to reduce theft it may be advantageous for animals to be sensitive to certain audience cues, such as whether they are attentive or not to the cache event. In this study, observations were made on three groups of Cape ground squirrels (Xerus inauris) in their natural habitat when they cached provisioned food items. When individuals cached within 10 m of conspecifics, we recorded the attentiveness (i.e. whether any audience members were orientated towards the cacher, had direct line of site and were not engaged in other activities) and identity of audience members. Overall, there was a preference to cache when audience members were inattentive rather than attentive. Additionally, we found rank effects related to cache avoidance whereby high-ranked individuals showed less avoidance to cache when audience members were attentive compared to medium- and low-ranked individuals. We suggest this audience sensitivity may have evolved in response to the difference in competitive ability amongst the ranks in how successful individuals are at winning foraging competitions. This study demonstrates that Cape ground squirrels have the ability to not only monitor the presence or absence of conspecifics but also discriminate individuals on the basis of their attentive state.

  15. [Molecular genetic relationships among east Palearctic ground squirrels of the genus Spermophilus (Sciuridae, Rodentia)].

    PubMed

    Tsvirka, M V; Spiridonova, L N; Korablev, V P

    2008-08-01

    Genetic diversity in the four east Palearctic ground squirrel species of the genus Spermophilus--S. undulatus, S. parryi (subgenus Urocitellus), S. dauricus, and S. relictus (subgenus Citellus)--- was investigated using RAPD PCR with ten random primers. Siberian chipmunk, Tamias sibiricus, was used as an outgroup. Molecular markers for different taxonomic ranks were identified, including those for the genera Spermophilus and Tamias, subgenera Urocitellus and Citellus, as well as for each of the four species, S. undulatus, S. parryi, S. dauricus, and S. relictus. For the ground squirrel species and subgenera, genetic differentiation indices (H(t), H(s), D(st), G(st), Nm, and D) were calculated. In addition, for these groups the NJ phylogenetic reconstructions and UPGMA dendrograms of genetic similarity of the individuals and combined populations were constructed. Comparative molecular genetic analysis revealed a high genetic differentiation between S. undulates, S. dauricus, S. relicts, and S. parryi (G(st) = 0.58 to 0.82; D = 0.53 to 1.06), along with a low level of genetic differentiation of the subgenera Citellus and Urocitellus (G(st) = 0.33; D = 0.27), distinguished in accordance with the existing taxonomic systems of the genus Spermophilus.

  16. Immunohistochemical localization of inhibin/activin subunits in the wild ground squirrel (Citellus dauricus Brandt) ovary.

    PubMed

    Sheng, Xia; Weng, Jiaju; Zhang, Haolin; Li, Xiaonan; Zhang, Mengyuan; Xu, Meiyu; Weng, Qiang; Watanabe, Gen; Taya, Kazuyoshi

    2012-01-01

    The intraovarian function of gonadally produced inhibin and activin has been extensively studied in experimental models for decades, yet their presence and function have been rarely reported in wild rodents. With our seasonal breeding model, the wild ground squirrel, we aimed to investigate the possible roles of these peptides in the seasonal folliculogenesis. Immunohistochemical staining and Western blotting have been used to detect the cellular localization and expression patterns of inhibin/activin subunits (α, β(A) and β(B)). In the breeding season ovary, all three subunits were present in granulosa cells, theca cells of antral follicles and interstitial cells, with the strongest immunostaining in granulosa cells. Following ovulation, the corpora lutea become a major site of inhibin/activin synthesis. In the nonbreeding season ovary, inhibin/activin α and β(A) subunits were weakly immunopositive in granulosa cells of early stage follicles, while β(B) subunit was undetectable. The expression level of inhibin/activin subunit proteins were generally higher in the ovaries of the breeding season, and then decreased to a relatively low level during the nonbreeding season. The dynamic expression of inhibin/activin subunits indicated that they might play important paracrine and/or autocrine roles during the seasonal folliculogenesis of the wild ground squirrel.

  17. Absolute, not relative brain size correlates with sociality in ground squirrels

    PubMed Central

    Matějů, Jan; Kratochvíl, Lukáš; Pavelková, Zuzana; Pavelková Řičánková, Věra; Vohralík, Vladimír; Němec, Pavel

    2016-01-01

    The social brain hypothesis (SBH) contends that cognitive demands associated with living in cohesive social groups favour the evolution of large brains. Although the correlation between relative brain size and sociality reported in various groups of birds and mammals provides broad empirical support for this hypothesis, it has never been tested in rodents, the largest mammalian order. Here, we test the predictions of the SBH in the ground squirrels from the tribe Marmotini. These rodents exhibit levels of sociality ranging from solitary and single-family female kin groups to egalitarian polygynous harems but feature similar ecologies and life-history traits. We found little support for the association between increase in sociality and increase in relative brain size. Thus, sociality does not drive the evolution of encephalization in this group of rodents, a finding inconsistent with the SBH. However, body mass and absolute brain size increase with sociality. These findings suggest that increased social complexity in the ground squirrels goes hand in hand with larger body mass and brain size, which are tightly coupled to each other. PMID:27009231

  18. Hibernation and circadian rhythms of body temperature in free-living Arctic ground squirrels.

    PubMed

    Williams, Cory T; Barnes, Brian M; Richter, Melanie; Buck, C Loren

    2012-01-01

    In mammals, the circadian master clock generates daily rhythms of body temperature (T(b)) that act to entrain rhythms in peripheral circadian oscillators. The persistence and function of circadian rhythms during mammalian hibernation is contentious, and the factors that contribute to the reestablishment of rhythms after hibernation are unclear. We collected regular measures of core T(b) (every 34 min) and ambient light conditions (every 30 s) before, during, and following hibernation in free-living male arctic ground squirrels. Free-running circadian T(b) rhythms at euthermic levels of T(b) persisted for up to 10 d in constant darkness after animals became sequestered in their hibernacula in fall. During steady state torpor, T(b) was constant and arrhythmic for up to 13 d (within the 0.19°C resolution of loggers). In spring, males ended heterothermy but remained in their burrows at euthermic levels of T(b) for 22-26 d; patterns of T(b) were arrhythmic for the first 10 d of euthermia. One of four squirrels exhibited a significant free-running T(b) rhythm (τ = 22.1 h) before emergence; this squirrel had been briefly exposed to low-amplitude light before emergence. In all animals, diurnal T(b) rhythms were immediately reestablished coincident with emergence to the surface and the resumption of surface activity. Our results support the hypothesis that clock function is inhibited during hibernation and reactivated by exposure to light, although resumption of extended surface activity does not appear to be necessary to reinitiate T(b) cycles.

  19. Effects of Season and Host Physiological State on the Diversity, Density, and Activity of the Arctic Ground Squirrel Cecal Microbiota

    PubMed Central

    Stevenson, Timothy J.; Duddleston, Khrystyne N.

    2014-01-01

    We examined the seasonal changes of the cecal microbiota of captive arctic ground squirrels (Urocitellus parryii) by measuring microbial diversity and composition, total bacterial density and viability, and short-chain fatty acid concentrations at four sample periods (summer, torpor, interbout arousal, and posthibernation). Abundance of Firmicutes was lower, whereas abundances of Bacteroidetes, Verrucomicrobia, and Proteobacteria were higher during torpor and interbout arousal than in summer. Bacterial densities and percentages of live bacteria were significantly higher in summer than during torpor and interbout arousal. Likewise, total short-chain fatty acid concentrations were significantly greater during summer than during torpor and interbout arousal. Concentrations of individual short-chain fatty acids varied across sample periods, with butyrate concentrations higher and acetate concentrations lower during summer than at all other sample periods. Characteristics of the gut community posthibernation were more similar to those during torpor and interbout arousal than to those during summer. However, higher abundances of the genera Bacteroides and Akkermansia occurred during posthibernation than during interbout arousal and torpor. Collectively, our results clearly demonstrate that seasonal changes in physiology associated with hibernation and activity affect the gut microbial community in the arctic ground squirrel. Importantly, similarities between the gut microbiota of arctic ground squirrels and thirteen-lined ground squirrels suggest the potential for a core microbiota during hibernation. PMID:25002417

  20. Late Pleistocene paleoecology of arctic ground squirrel ( Urocitellus parryii) caches and nests from Interior Alaska's mammoth steppe ecosystem, USA

    NASA Astrophysics Data System (ADS)

    Gaglioti, Benjamin V.; Barnes, Brian M.; Zazula, Grant D.; Beaudoin, Alwynne B.; Wooller, Matthew J.

    2011-11-01

    Botanical analyses of fossil and modern arctic ground squirrel ( Urocitellus parryii) caches and nests have been used to reconstruct the past vegetation from some parts of Beringia, but such archives are understudied in Alaska. Five modern and four fossil samples from arctic ground squirrel caches and nests provide information on late Pleistocene vegetation in Eastern Beringia. Modern arctic ground squirrel caches from Alaska's arctic tundra were dominated by willow and grass leaves and grass seeds and bearberries, which were widespread in the local vegetation as confirmed by vegetation surveys. Late Pleistocene caches from Interior Alaska were primarily composed of steppe and dry tundra graminoid and herb seeds. Graminoid cuticle analysis of fossil leaves identified Calamagrostis canadensis, Koeleria sp. and Carex albonigra as being common in the fossil samples. Stable carbon isotopes analysis of these graminoid specimens indicated that plants using the C 3 photosynthetic pathways were present and functioning with medium to high water-use efficiency. Fossil plant taxa and environments from ground squirrel caches in Alaska are similar to other macrofossil assemblages from the Yukon Territory, which supports the existence of a widespread mammoth steppe ecosystem type in Eastern Beringia that persisted throughout much of the late Pleistocene.

  1. Effects of season and host physiological state on the diversity, density, and activity of the arctic ground squirrel cecal microbiota.

    PubMed

    Stevenson, Timothy J; Duddleston, Khrystyne N; Buck, C Loren

    2014-09-01

    We examined the seasonal changes of the cecal microbiota of captive arctic ground squirrels (Urocitellus parryii) by measuring microbial diversity and composition, total bacterial density and viability, and short-chain fatty acid concentrations at four sample periods (summer, torpor, interbout arousal, and posthibernation). Abundance of Firmicutes was lower, whereas abundances of Bacteroidetes, Verrucomicrobia, and Proteobacteria were higher during torpor and interbout arousal than in summer. Bacterial densities and percentages of live bacteria were significantly higher in summer than during torpor and interbout arousal. Likewise, total short-chain fatty acid concentrations were significantly greater during summer than during torpor and interbout arousal. Concentrations of individual short-chain fatty acids varied across sample periods, with butyrate concentrations higher and acetate concentrations lower during summer than at all other sample periods. Characteristics of the gut community posthibernation were more similar to those during torpor and interbout arousal than to those during summer. However, higher abundances of the genera Bacteroides and Akkermansia occurred during posthibernation than during interbout arousal and torpor. Collectively, our results clearly demonstrate that seasonal changes in physiology associated with hibernation and activity affect the gut microbial community in the arctic ground squirrel. Importantly, similarities between the gut microbiota of arctic ground squirrels and thirteen-lined ground squirrels suggest the potential for a core microbiota during hibernation.

  2. Characterisation of a novel UV filter in the lens of the thirteen-lined ground squirrel (Ictidomys tridecemlineatus).

    PubMed

    Lyons, Brian; Karuso, Peter; Jamie, Joanne F; Simpanya, Mukoma F; Giblin, Frank; Truscott, Roger J W

    2014-04-01

    Structural analysis of a novel UV filter present in the lens of the thirteen-lined ground squirrel has shown that it is related in structure to N-acetyl-3-hydroxykynurenine. This finding is consistent with the fact that the squirrel lenses also contain high levels of this tryptophan metabolite. Analysis of both NMR and mass spectrometric data suggested that the novel UV filter compound forms by condensation of proline with N-acetyl-3-hydroxykynurenine. Its absorption maximum at 340 nm is more than 20 nm lower than that of the kynurenines and it may therefore assist in filtering the more damaging shorter wavelengths of UVA.

  3. Determination of an optimal dose of medetomidine-ketamine-buprenorphine for anaesthesia in the Cape ground squirrel (Xerus inauris).

    PubMed

    Jouber, K E; Serfontein, T; Scantlebury, M; Manjerovice, M B; Bateman, P W; Bennett, N C; Waterman, J M

    2011-06-01

    The optimal dose of medetomidine-ketamine-buprenorphine was determined in 25 Cape ground squirrels (Xerus inauris) undergoing surgical implantation of a temperature logger into the abdominal cavity. At the end of anaesthesia, the squirrels were given atipamezole intramuscularly to reverse the effects of medetomidine. The mean dose of medetomidine was 67.6 +/- 9.2microg/kg, ketamine 13.6 +/- 1.9 mg/kg and buprenorphine 0.5 +/- 0.06 microg/kg. Induction time was 3.1 +/- 1.4 min. This produced surgical anaesthesia for 21 +/- 4.2 min. Atipamezole 232 +/- 92 microg/kg produced a rapid recovery. Squirrels were sternally recumbent in 3.5 +/- 2.2 min.

  4. The secret life of ground squirrels: accelerometry reveals sex-dependent plasticity in above-ground activity.

    PubMed

    Williams, Cory T; Wilsterman, Kathryn; Zhang, Victor; Moore, Jeanette; Barnes, Brian M; Buck, C Loren

    2016-09-01

    The sexes differ in how and when they allocate energy towards reproduction, but how this influences phenotypic plasticity in daily activity patterns is unclear. Here, we use collar-mounted light loggers and triaxial accelerometers to examine factors that affect time spent above ground and overall dynamic body acceleration (ODBA), an index of activity-specific energy expenditure, across the active season of free-living, semi-fossorial arctic ground squirrels (Urocitellus parryii). We found high day-to-day variability in time spent above ground and ODBA with most of the variance explained by environmental conditions known to affect thermal exchange. In both years, females spent more time below ground compared with males during parturition and early lactation; however, this difference was fourfold larger in the second year, possibly, because females were in better body condition. Daily ODBA positively correlated with time spent above ground in both sexes, but females were more active per unit time above ground. Consequently, daily ODBA did not differ between the sexes when females were early in lactation, even though females were above ground three to six fewer hours each day. Further, on top of having the additional burden of milk production, ODBA data indicate females also had fragmented rest patterns and were more active during late lactation. Our results indicate that sex differences in reproductive requirements can have a substantial influence on activity patterns, but the size of this effect may be dependent on capital resources accrued during gestation.

  5. The secret life of ground squirrels: accelerometry reveals sex-dependent plasticity in above-ground activity

    PubMed Central

    Wilsterman, Kathryn; Zhang, Victor; Moore, Jeanette; Barnes, Brian M.; Buck, C. Loren

    2016-01-01

    The sexes differ in how and when they allocate energy towards reproduction, but how this influences phenotypic plasticity in daily activity patterns is unclear. Here, we use collar-mounted light loggers and triaxial accelerometers to examine factors that affect time spent above ground and overall dynamic body acceleration (ODBA), an index of activity-specific energy expenditure, across the active season of free-living, semi-fossorial arctic ground squirrels (Urocitellus parryii). We found high day-to-day variability in time spent above ground and ODBA with most of the variance explained by environmental conditions known to affect thermal exchange. In both years, females spent more time below ground compared with males during parturition and early lactation; however, this difference was fourfold larger in the second year, possibly, because females were in better body condition. Daily ODBA positively correlated with time spent above ground in both sexes, but females were more active per unit time above ground. Consequently, daily ODBA did not differ between the sexes when females were early in lactation, even though females were above ground three to six fewer hours each day. Further, on top of having the additional burden of milk production, ODBA data indicate females also had fragmented rest patterns and were more active during late lactation. Our results indicate that sex differences in reproductive requirements can have a substantial influence on activity patterns, but the size of this effect may be dependent on capital resources accrued during gestation. PMID:27703706

  6. Effects of Hypothermia and Self-Warming on Activity of Ca(2+)-Dependent Neutral Proteases in Tissues of Ground Squirrels and Rats.

    PubMed

    Nurmagomedova, P M; Emirbekov, E Z; Abasova, M M

    2016-04-01

    Effects of hypothermia and subsequent self-warming on activity of Ca(2+)-dependent neutral proteases were studied in tissues of ground squirrels and rats. Moderate hypothermia did not significantly change activity of Ca(2+)-dependent neutral proteases in the analyzed tissues of ground squirrels, but reduced protease activity in rat heart. Severe hypothermia reduced enzyme activity in the analyzed tissues of rats and ground squirrels. Differences in activity of Ca(2+)-dependent neutral proteases after long-term hypothermia and subsequent self-warming were found only in the heart.

  7. [Seasonal changes in phosphorylation of myosin regulatory light chains and C-protein in myocardium of hibernating ground squirrel Citellus undulatus].

    PubMed

    Malyshev, S L; Osipova, D A; Vikhliantsev, I M; Podlubnaia, Z A

    2006-01-01

    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 C-protein during hibernation is about two times higher than that in the active state. Seasonal differences in phosphorylation of the two proteins of ground squirrel myocardium are discussed in the context of adaptation to hibernation.

  8. Analysis of the hibernation cycle using LC-MS-based metabolomics in ground squirrel liver.

    PubMed

    Nelson, Clark J; Otis, Jessica P; Martin, Sandra L; Carey, Hannah V

    2009-03-03

    A hallmark of hibernation in mammals is metabolic flexibility, which is typified by reversible bouts of metabolic depression (torpor) and the seasonal shift from predominantly carbohydrate to lipid metabolism from summer to winter. To provide new insight into the control and consequences of hibernation, we used LC/MS-based metabolomics to measure differences in small molecules in ground squirrel liver in five activity states: summer, entering torpor, late torpor, arousing from torpor, and interbout arousal. There were significant alterations both seasonally and within torpor-arousal cycles in enzyme cofactor metabolism, amino acid catabolism, and purine and pyrimidine metabolism, with observed metabolites reduced during torpor and increased upon arousal. Multiple lipids also changed, including 1-oleoyllysophosphatidylcholine, cholesterol sulfate, and sphingosine, which tended to be lowest during torpor, and hexadecanedioic acid, which accumulated during a torpor bout. The results reveal the dramatic alterations that occur in several classes of metabolites, highlighting the value of metabolomic analyses in deciphering the hibernation phenotype.

  9. The effects of hibernation and forced disuse (neurectomy) on bone properties in arctic ground squirrels.

    PubMed

    Bogren, Lori K; Johnston, Erin L; Barati, Zeinab; Martin, Paula A; Wojda, Samantha J; Van Tets, Ian G; LeBlanc, Adrian D; Donahue, Seth W; Drew, Kelly L

    2016-05-01

    Bone loss is a well-known medical consequence of disuse such as in long-term space flight. Immobilization in many animals mimics the effects of space flight on bone mineral density. Decreases in metabolism are also thought to contribute to a loss of skeletal mass. Hibernating mammals provide a natural model of disuse and metabolic suppression. Hibernating ground squirrels have been shown to maintain bone strength despite long periods of disuse and decreased metabolism during torpor. This study examined if the lack of bone loss during torpor was a result of the decrease in metabolic rate during torpor or an evolutionary change in these animals affording protection against disuse. We delineated changes in bone density during natural disuse (torpor) and forced disuse (sciatic neurectomy) in the hind limbs of the arctic ground squirrel (AGS) over an entire year. We hypothesized that the animals would be resistant to bone loss due to immobilization and disuse during the winter hibernation season when metabolism is depressed but not the summer active season. This hypothesis was not supported. The animals maintained bone density (dual-energy X-ray absorptiometry) and most bone structural and mechanical properties in both seasons. This was observed in both natural and forced disuse, regardless of the known metabolic rate increase during the summer. However, trabecular bone volume fraction (microcomputed tomography) in the distal femur was lower in neurectomized AGS at the study endpoint. These results demonstrate a need to better understand the relationship between skeletal load (use) and bone density that may lead to therapeutics or strategies to maintain bone density in disuse conditions.

  10. The effect of hibernation on protein phosphatases from ground squirrel organs.

    PubMed

    MacDonald, Justin A; Storey, Kenneth B

    2007-12-15

    Protein phosphorylation has been identified as a reversible mechanism for the regulated suppression of metabolism and thermogenesis during mammalian hibernation. The effects of hibernation on the activity of serine/threonine and tyrosine protein phosphatases (PP1, PP2A, PP2C and PTPs) were assessed in five organs of Richardson's ground squirrel. Each phosphatase subfamily responded differently during torpor, and each showed organ-specific patterns of activity changes. The distribution of PP1 catalytic subunit (PP1c) isoforms (alpha, delta, gamma1) was assessed in five organs, and changes in the subcellular distribution of PP1 were observed during hibernation in liver and muscle. For example, in muscle, cytosolic PP1 content increased and myofibril-associated PP1 decreased during torpor. PP1c from ground squirrel liver was purified to homogeneity and characterized; temperature effects on PP1c maximal activity suggested that temperature had little or no effect on relative dephosphorylation potential at low temperatures. However, nucleotide inhibition of PP1c by ATP, ADP and AMP was much weaker at 5 degrees C compared with 37 degrees C assay temperatures. PP2A activity decreased in three organs (brown adipose, kidney, brain) during hibernation whereas PP2C activity was increased in liver and brain. PTPs were assessed using both a general substrate (ENDpYINASL) and a substrate (DADEpYLIPQQG) specific for PTPs containing the SH2-binding site; both revealed hibernation-associated changes in PTP activities. Changes in protein phosphatase activities suggest the relative importance of these modules in controlling metabolic function and cellular processes during mammalian hibernation.

  11. Demography of a population collapse: the Northern Idaho ground squirrel (Spermophilus brunneus brunneus)

    USGS Publications Warehouse

    Sherman, P.W.; Runge, M.C.

    2002-01-01

    We studied the demography of a population of Northern Idaho ground squirrels (Spermophilus brunneus brunneus) in Adams Co., Idaho. The population was completely censused yearly from 1987 to 1999, during which time it declined from 272 to 10 animals. The finite population growth rate, based on a Leslie matrix model of average life-history parameters, was only 0.72 (i.e., significantly <1.0). Growth rate was more sensitive to proportional changes in juvenile female survival than to any other single life-history parameter. Comparisons with self-sustaining populations of closely related ground squirrel species revealed that juvenile survival and breeding rates of yearling females were anomalously low. We believe that the ultimate cause of the population's collapse was inadequacy of food resources, particularly seeds, due to drying of the habitat and changes in plant species composition, likely the result of fire suppression and grazing. No 'rescue' by immigration occurred, probably because S. b. brunneus seldom disperse long distances and fire suppression has allowed conifers to encroach on inhabited meadows, shrinking them and closing dispersal routes. The proximate cause of the population's collapse was mortality of older breeding females, which reduced the mean age of breeders. Younger females had lower average pregnancy rates and litter sizes. To place our results in context we developed a new, general classification of anthropogenic population declines, based on whether they are caused by changes in the means of the life-history parameters (blatant disturbances), their variances (inappropriate variations), or the correlations among them (evolutionary traps). Many S. b. brunneus populations have disappeared in recent years, apparently due to blatant disturbances, especially loss of habitat and changes in food-plant composition, resulting in inadequate prehibernation nutrition and starvation overwinter. In addition, our study population may have been caught in an

  12. Expression profiling and structural characterization of microRNAs in adipose tissues of hibernating ground squirrels.

    PubMed

    Wu, Cheng-Wei; Biggar, Kyle K; Storey, Kenneth B

    2014-12-01

    MicroRNAs (miRNAs) are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 miRNAs in brown (BAT) and white adipose tissue (WAT) during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six miRNAs including let-7a, let-7b, miR-107, miR-150, miR-222 and miR-31 was significantly downregulated in WAT (P<0.05), which was 16%-54% of euthermic non-torpid control squirrels, whereas expression of three miRNAs including miR-143, miR-200a and miR-519d was found to be upregulated by 1.32-2.34-fold. Similarly, expression of more miRNAs was downregulated in BAT during torpor. We detected reduced expression of 6 miRNAs including miR-103a, miR-107, miR-125b, miR-21, miR-221 and miR-31 (48%-70% of control), while only expression of miR-138 was significantly upregulated (2.91±0.8-fold of the control, P<0.05). Interestingly, miRNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas miRNAs with altered expression in BAT during torpor were linked to mitochondrial β-oxidation. miRPath target prediction analysis showed that miRNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase (MAPK) signaling, while the miRNAs upregulated in WAT were linked to transforming growth factor β (TGFβ) signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-miRNAs for the miRNAs used in this study, suggesting no structure-influenced changes in pre-miRNA processing efficiency in the squirrel. As well, the expression of miRNA processing enzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of miRNA expression in adipose tissues may be linked to distinct

  13. Expression Profiling and Structural Characterization of MicroRNAs in Adipose Tissues of Hibernating Ground Squirrels

    PubMed Central

    Wu, Cheng-Wei; Biggar, Kyle K.; Storey, Kenneth B.

    2014-01-01

    MicroRNAs (miRNAs) are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 miRNAs in brown (BAT) and white adipose tissue (WAT) during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six miRNAs including let-7a, let-7b, miR-107, miR-150, miR-222 and miR-31 was significantly downregulated in WAT (P < 0.05), which was 16%–54% of euthermic non-torpid control squirrels, whereas expression of three miRNAs including miR-143, miR-200a and miR-519d was found to be upregulated by 1.32–2.34-fold. Similarly, expression of more miRNAs was downregulated in BAT during torpor. We detected reduced expression of 6 miRNAs including miR-103a, miR-107, miR-125b, miR-21, miR-221 and miR-31 (48%–70% of control), while only expression of miR-138 was significantly upregulated (2.91 ± 0.8-fold of the control, P < 0.05). Interestingly, miRNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas miRNAs with altered expression in BAT during torpor were linked to mitochondrial β-oxidation. miRPath target prediction analysis showed that miRNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase (MAPK) signaling, while the miRNAs upregulated in WAT were linked to transforming growth factor β (TGFβ) signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-miRNAs for the miRNAs used in this study, suggesting no structure-influenced changes in pre-miRNA processing efficiency in the squirrel. As well, the expression of miRNA processing enzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of miRNA expression in adipose tissues may be linked

  14. Changes in calpains and calpastatin in the soleus muscle of Daurian ground squirrels during hibernation.

    PubMed

    Yang, Chen-Xi; He, Yue; Gao, Yun-Fang; Wang, Hui-Ping; Goswami, Nandu

    2014-10-01

    We investigated changes in muscle mass, calpains, calpastatin and Z-disk ultrastructure in the soleus muscle (SOL) of Daurian ground squirrels (Spermophilus dauricus) after hibernation or hindlimb suspension to determine possible mechanisms by which muscle atrophy is prevented in hibernators. Squirrels (n=30) were divided into five groups: no hibernation group (PRE, n=6); hindlimb suspension group (HLS, n=6); two month hibernation group (HIB, n=6); two day group after 90±12 days of hibernation (POST, n=6); and forced exercise group (one time forced, moderate-intensity treadmill exercise) after arousal (FE, n=6). Activity and protein expression of calpains were determined by casein zymography and western blotting, and Z-disk ultrastructure was observed by transmission electron microscopy. The following results were found. Lower body mass and higher SOL muscle mass (mg) to total body mass (g) ratio were observed in HIB and POST; calpain-1 activity increased significantly by 176% (P=0.034) in HLS compared to the PRE group; no significant changes were observed in calpain-2 activity. Protein expression of calpain-1 and calpain-2 increased by 83% (P=0.041) and 208% (P=0.029) in HLS compared to the PRE group, respectively; calpastatin expression increased significantly by 180% (P<0.001) and 153% (P=0.007) in HIB and POST, respectively; the myofilaments were well-organized, and the width of the sarcomere and the Z-disk both appeared visually similar among the pre-hibernation, hibernating and post-hibernation animals. Inhibition of calpain activity and consequently calpain-mediated protein degradation by highly elevated calpastatin protein expression levels may be an important mechanism for preventing muscle protein loss during hibernation and ensuring that Z-lines remained ultrastructurally intact.

  15. Photocurrents of cone photoreceptors of the golden-mantled ground squirrel.

    PubMed

    Kraft, T W

    1988-10-01

    1. Visual transduction in photoreceptors of the ground squirrel, Citellus lateralis, was studied by recording membrane current from individual cones in small pieces of retina. 2. Brief flashes of light produced transient reductions of the dark current; saturating response amplitudes were up to 67 pA. A flash strength of about 11,000 photons microns-2 at lambda max was required to give a half-saturating response. The stimulus-response relation was well fitted by an exponential saturation curve. Responses below 20% of maximum behaved linearly. 3. The response to a dim flash in most cells had a time to peak of 20-30 ms and resembled the impulse response of a series of five low-pass filters. 4. The variance of the dim-flash response amplitude put an upper limit of 80 fA on the size of the single photon response. Estimates based on the effective collecting area suggest the single photon response to be of the order of 10 fA. 5. Flash responses of squirrel cones usually lacked the undershoot observed in primate cones, although in about 1/3 of the cells a small undershoot developed during recording. 6. Background lights slightly shortened the time to peak of the flash response and reduced the integration time. 7. Spectral sensitivity measurements showed two classes of cones with peak sensitivities at about 520 and 435 nm. Rod sensitivity peaked near 500 nm. Spectral univariance was obeyed by all three classes of cells. 8. The shapes of the spectral sensitivity curves of the rod and both types of cones were similar to each other when plotted on a log wave number scale, but differed significantly from similar plots of monkey and human cone spectra. 9. The kinetics and sensitivity of flash responses of the blue- and green-sensitive cones were indistinguishable.

  16. Expression of myocyte enhancer factor-2 and downstream genes in ground squirrel skeletal muscle during hibernation.

    PubMed

    Tessier, Shannon N; Storey, Kenneth B

    2010-11-01

    Myocyte enhancer factor-2 (MEF2) transcription factors regulate the expression of a variety of genes encoding contractile proteins and other proteins associated with muscle performance. We proposed that changes in MEF2 levels and expression of selected downstream targets would aid the skeletal muscle of thirteen-lined ground squirrels (Spermophilus tridecemlineatus) in meeting metabolic challenges associated with winter hibernation; e.g., cycles of torpor-arousal, body temperature that can fall to near 0°C, long periods of inactivity that could lead to atrophy. MEF2A protein levels were significantly elevated when animals were in torpor (maximally 2.8-fold higher than in active squirrels) and the amount of phosphorylated active MEF2A Thr312 increased during entrance into torpor. MEF2C levels also rose significantly during entrance and torpor as did the amount of phosphorylated MEF2C Ser387. Furthermore, both MEF2 members showed elevated amounts in the nuclear fraction during torpor as well as enhanced binding to DNA indicating that MEF2-mediated gene expression was up-regulated in torpid animals. Indeed, the protein products of two MEF2 downstream gene targets increased in muscle during torpor (glucose transporter isoforms 4; GLUT4) or early arousal (myogenic differentiation; MyoD). Significant increases in Glut4 and MyoD mRNA transcript levels correlated with the rise in protein product levels and provided further support for the activation of MEF2-mediated gene expression in the hibernator. Transcript levels of Mef2a and Mef2c also showed time-dependent patterns with levels of both being highest during arousal from torpor. The data suggest a significant role for MEF2-mediated gene transcription in the selective adjustment of muscle protein complement over the course of torpor-arousal cycles.

  17. [Dynamics of colonies of the speckled ground squirrel (Spermophilus suslicus Guld., 1770) on the northern boundary of the habitat].

    PubMed

    Shilova, S A; Neronov, V V; Shekarova, O N; Savinetskaia, L E

    2010-01-01

    Results of studies in 1999-2009 of the dynamics of five isolated colonies of the speckled ground squirrel (Spermophilus suslicus) at the northern boundary of the habitat of this species (Zaraiskii area, Moscow oblast) are given. An abrupt decrease in the number of this species in colonies was established, as was a multifold decrease (up to 70-90%) in suitable habitats due to the plowing of meadows and build-up of the area. The fragmentation of the optimum habitat of ground squirrels reached a stage where colonies can no longer exist as a stable autonomous system. The process of their extinction unfolds quickly: the number of animals in some colonies decreased five-six times over the last ten years. To preserve this species, it is necessary to create areas of steppefied meadows with regulated agricultural use.

  18. Environmental effects of solar-thermal power systems. Systematic status of the Mojave ground squirrel, Spermophilus mohavensis (subgenus Xerospermophilus)

    SciTech Connect

    Hafner, D.J.; Yates, T.L.

    1982-06-01

    The Mojave ground squirrel, Spermophilus mohavensis, is listed as a rare species by The California Fish and Game Commission. Its well-being has emerged as an environmental concern associated with deployment of solar thermal power systems in western parts of the Motave Desert. The more common round-tailed ground squirrel, Spermophilus tereticaudus, also occurs in the Mojave Desert, and this species closely resembles S. mohavensis. The systematic status of the sibling species was investigated using allozymic and chromosomal data. Karyotypically, the two species differ in diploid number while they share a level of genic similarity reported for other mammalian semispecies. Hybridization was detected only at a single disturbed site, while allelic introgression was confined to an estimated 60 km reach. The two taxa are retained as full biological species.

  19. Seasonal changes in microsomal fraction enriched with Na,K-ATPase from kidneys of the ground squirrel Spermophilus undulatus.

    PubMed

    Basevich, E V; Lopina, O D; Rubtsov, A M

    2010-11-01

    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 change in isoenzyme composition. Seasonal changes of Na,K-ATPase α-subunit phosphorylation level by endogenous protein kinases were not found. Proteins which could be potential regulators of Na,K-ATPase activity were not found among phosphorylated proteins of the microsomes. Analysis of the composition and properties of the lipid phase of microsomes showed that the total level of unsaturation of fatty acids and the lipid/protein ratio are not changed significantly during hibernation, whereas the cholesterol content in preparations from kidneys of hibernating ground squirrels is approximately twice higher than that in preparations from kidneys of active animals. However, using spin and fluorescent probes it was shown that this difference in cholesterol content does not affect the integral membrane microviscosity of microsomes. Using the cross-linking agent cupric phenanthroline, it was shown that Na,K-ATPase in membranes of microsomes from kidneys of hibernating ground squirrels is present in more aggregated state in comparison with membranes of microsomes from kidneys of active animals. We suggest that the decrease in Na,K-ATPase activity in kidneys of ground squirrels during hibernation is mainly connected with the aggregation of proteins in plasma membrane.

  20. Antibodies to pre-S and X determinants arise during natural infection with ground squirrel hepatitis virus.

    PubMed Central

    Persing, D H; Varmus, H E; Ganem, D

    1986-01-01

    The DNA sequence of the ground squirrel hepatitis virus (GSHV) genome predicts the existence of several proteins in addition to the major surface (S) and core antigens. These include the pre-S1 and pre-S2 proteins, initiated at sites within the open reading frame preceding and continuous with the coding region for the S gene product, and the X protein, the putative product of an independent reading frame. Using an antibody directed against a peptide predicted by codons 130 to 143 of the pre-S1 reading frame, we identified a 43-kilodalton product of the pre-S1 coding region in preparations of GSHV surface antigen purified from the sera of infected animals. In addition, by immunoprecipitation of S- and pre-S-specific in vitro translation products with ground squirrel sera obtained after GSHV infection, we determined that antibodies arise to both S and pre-S determinants. The antibody response to pre-S includes, in some cases, reactivity to pre-S1-specific domains and is not always associated with an anti-S response. Similarly, by production of the viral X gene product in vitro followed by immunoprecipitation with ground squirrel sera, we showed that antibodies to this viral gene product also arise during infection, indicating that X antigenic determinants are synthesized during viral infection and are recognized by the host immune system. Images PMID:2427746

  1. Environmental effects of solar-thermal-power systems. Systematic status of the Mojave ground squirrel, Spermophilus mohavensis (subgenus Xerospermophilus)

    SciTech Connect

    Hafner, D.J.; Yates, T.L.

    1982-06-01

    The Mojave ground squirrel, Spermophilus mohavensis, is listed as a rare species by the California Fish and Game Commission. Its well-being has emerged as an environmental concern associated with deployment of solar thermal power systems in western parts of the Mojave Desert. The more common round-tailed ground squirrel, Spermophilus tereticaudus, also occurs in the Mojave Desert, and this species closely resembles S. mohavensis. In some areas it may be extremely difficult, on the basis of external characters, to identify the species present. The systematic status of the sibling species Spermophilus mohavensis and S. tereticaudus (subgenus Xerosphermophilus) was investigated throughout the range of the subgenus, based on allozymic and chromosomal data. Hybridization of the two species was detected only at a single disturbed site, while allelic introgression was confined to an estimated 60 km reach of the Mojave River wash. In the absence of an analysis of a zone of natural sympatry, the two taxa are retained as full biological species. The population of ground squirrels just east of Solar One, the 10 MWe pilot solar thermal power plant, is composed of individuals referable to S. tereticaudus based on both allozymic and chromosomal criteria.

  2. (14C)2-deoxyglucose uptake in ground squirrel brain during hibernation

    SciTech Connect

    Kilduff, T.S.; Sharp, F.R.; Heller, H.C.

    1982-02-01

    Autoradiographic patterns of (14C)2-deoxyglucose uptake are described throughout the brains of hibernating and euthermic ground squirrels. Autoradiographs of the brains of hibernating animals are generally homogeneous in comparison to euthermic animals; hence, the relative 2-deoxyglucose uptake (R2DGU) of gray to white matter for the majority of the 85 neural structures examined decreases during hibernation. Two categories of structures are identified as potentially important in hibernation: (1) structures that have the highest R2DGU during hibernation (cochlear nucleus, paratrigeminal nucleus, and superior colliculus) and (2) structures that undergo the least reduction in R2DGU in the transition from euthermia to hibernation (suprachiasmatic nucleus and lateral septal nucleus). The percentage of reduction in R2DGU that a structure undergoes in the transition from euthermia to hibernation is proportional to the R2DGU of that structure during euthermia. The suprachiasmatic, paratrigeminal, and cochlear nuclei undergo less of a reduction than would be predicted from this relationship and may be particularly important during hibernation. Sensory nuclei that receive primary afferent projections are among the structures with the highest R2DGU during hibernation. These metabolically active structures may be responsible for the sensitivity of the hibernator to environmental stimuli.

  3. Inverted-U shape relationship between cortisol and learning in ground squirrels.

    PubMed

    Mateo, Jill M

    2008-05-01

    Adrenal hormones regulate glucose levels, responses to unpredictable stressors and modulate cognition. Glucocorticoids can have an inverted-U shape relationship with cognition, as very low or high levels impair, whereas moderate elevations facilitate, acquisition and retention of memories. To date these relationships have been tested with humans and rodents in laboratory settings rather than with wild animals in biologically relevant contexts. This study examined whether the elevated cortisol observed in juvenile Belding's ground squirrels (Spermophilus beldingi) at natal emergence might promote both acquisition of adaptive responses to this species' two alarm calls warning of predators and memory of the spatial configuration of mothers' territories. Both experimentally increased and decreased basal cortisol levels interfere with acquisition and retention of an association between a warning call and the appropriate response compared with naturally occurring moderately elevated cortisol. Further, decreased cortisol impairs learning of a novel, complex spatial maze. Thus in the field the brief elevation of cortisol at emergence might facilitate acquisition of spatial memory of a three-dimensional environment and responses to alarm calls during a sensitive period of learning. This novel demonstration of the inverted-U shape function in a wild animal suggests that natural selection has favored a hormonal profile facilitating rapid acquisition of important survival behaviors.

  4. Using the Ground Squirrel (Marmota bobak) as an Animal Model to Assess Monkeypox Drug Efficacy.

    PubMed

    Sergeev, A A; Kabanov, A S; Bulychev, L E; Sergeev, A A; Pyankov, O V; Bodnev, S A; Galahova, D O; Zamedyanskaya, A S; Titova, K A; Glotova, T I; Taranov, O S; Omigov, V V; Shishkina, L N; Agafonov, A P; Sergeev, A N

    2017-02-01

    In experiments to study the sensitivity of ground squirrels (Marmota bobak) to monkeypox virus (MPXV) at intranasal challenge, expressed pox-like clinical symptoms (hyperthermia, lymphadenitis, skin rash all over the body and mucous membranes and others) were observed 7-9 days post-infection. The 50% infective dose (ID50 ) of MPXV for these marmots determined by the presence of clinical signs of the disease was 2.2 log10 PFU. Some diseased marmots (about 40%) died 13-22 days post-infection, and the mortality rate was weakly dependent on MPXV infective dose. Lungs with trachea were primary target organs of marmots challenged intranasally (with ~30 ID50 ). The pathogen got to secondary target organs of the animals mainly via the lymphatic way (with replication in bifurcation lymph nodes). Lungs with trachea, nasal mucosa and skin were the organs where the maximum MPXV amounts accumulated in these animals. Evidences of the pathogen presence and replication were revealed in these and subcutaneously infected marmots in the traditional primary target cells for MPXV (macrophages and respiratory tract epitheliocytes), as well as in some other cells (endotheliocytes, plasmocytes, fibroblasts, reticular and smooth muscle cells). Our use of this animal species to assess the antiviral efficacy of some drugs demonstrated the agreement of the obtained results with those described in scientific literature, which opens up the prospects of using marmots as animal models for monkeypox to develop therapeutic and preventive anti-smallpox drugs.

  5. Growth and differentiation of adult hippocampal arctic ground squirrel neural stem cells.

    PubMed

    Drew, Kelly L; McGee, Rebecca C; Wells, Matthew S; Kelleher-Andersson, Judith A

    2011-01-07

    Arctic ground squirrels (Urocitellus parryii, AGS) are unique in their ability to hibernate with a core body temperature near or below freezing. These animals also resist ischemic injury to the brain in vivo and oxygen-glucose deprivation in vitro. These unique qualities provided the impetus to isolate AGS neurons to examine inherent neuronal characteristics that could account for the capacity of AGS neurons to resist injury and cell death caused by ischemia and extremely cold temperatures. Identifying proteins or gene targets that allow for the distinctive properties of these cells could aid in the discovery of effective therapies for a number of ischemic indications and for the study of cold tolerance. Adult AGS hippocampus contains neural stem cells that continue to proliferate, allowing for easy expansion of these stem cells in culture. We describe here methods by which researchers can utilize these stem cells and differentiated neurons for any number of purposes. By closely following these steps the AGS neural stem cells can be expanded through two passages or more and then differentiated to a culture high in TUJ1-positive neurons (~50%) without utilizing toxic chemicals to minimize the number of dividing cells. Ischemia induces neurogenesis and neurogenesis which proceeds via MEK/ERK and PI3K/Akt survival signaling pathways contributes to ischemia resistance in vivo and in vitro (Kelleher-Anderson, Drew et al., in preparation). Further characterization of these unique neural cells can advance on many fronts, using some or all of these methods.

  6. Multilocus phylogeography of the European ground squirrel: cryptic interglacial refugia of continental climate in Europe.

    PubMed

    Říčanová, Štěpánka; Koshev, Yordan; Říčan, Oldřich; Ćosić, Nada; Ćirović, Duško; Sedláček, František; Bryja, Josef

    2013-08-01

    The theory of classical and cryptic Pleistocene refugia is based mainly on historical changes in temperature, and the refugia are usually defined within a latitudinal gradient. However, the gradient of oceanic-continental climate (i.e. longitudinal) was also significantly variable during glacial cycles with important biotic consequences. Range-wide phylogeography of the European ground squirrel (EGS) was used to interpret the evolutionary and palaeogeographical history of the species in Europe and to shed light on its glacial-interglacial dynamic. The EGS is a steppe-inhabiting species and the westernmost member of the genus in the Palaearctic region. We have analysed 915 specimens throughout the present natural range by employing mitochondrial DNA sequences (cytochrome b gene) and 12 nuclear microsatellite markers. The reconstructed phylogeography divides the species into two main geographical groups, with deep substructuring within both groups. Bulgaria is the centre of the ancestral area, and it also has the highest genetic diversity within the species. The northernmost group of the EGS survived in the southern part of Pannonia throughout several glacial-interglacial cycles. Animals from this population probably repeatedly colonized areas further to the north and west during the glacial periods, while in the interglacial periods, the EGS distribution contracted back to this Pannonian refugium. The EGS thus represents a species with a glacial expansion/interglacial contraction palaeogeographical dynamics, and the Pannonian and southeastern Balkanian steppes are supported as cryptic refugia of continental climate during Pleistocene interglacials.

  7. DNA analysis of a 30,000-year-old Urocitellus glacialis from northeastern Siberia reveals phylogenetic relationships between ancient and present-day arctic ground squirrels

    PubMed Central

    Faerman, Marina; Bar-Gal, Gila Kahila; Boaretto, Elisabetta; Boeskorov, Gennady G.; Dokuchaev, Nikolai E.; Ermakov, Oleg A.; Golenishchev, Fedor N.; Gubin, Stanislav V.; Mintz, Eugenia; Simonov, Evgeniy; Surin, Vadim L.; Titov, Sergei V.; Zanina, Oksana G.; Formozov, Nikolai A.

    2017-01-01

    In contrast to the abundant fossil record of arctic ground squirrels, Urocitellus parryii, from eastern Beringia, only a limited number of fossils is known from its western part. In 1946, unnamed GULAG prisoners discovered a nest with three mummified carcasses of arctic ground squirrels in the permafrost sediments of the El’ga river, Yakutia, Russia, that were later attributed to a new species, Citellus (Urocitellus) glacialis Vinogr. To verify this assignment and to explore phylogenetic relationships between ancient and present-day arctic ground squirrels, we performed 14C dating and ancient DNA analyses of one of the El’ga mummies and four contemporaneous fossils from Duvanny Yar, northeastern Yakutia. Phylogenetic reconstructions, based on complete cytochrome b gene sequences of five Late Pleistocene arctic ground squirrels and those of modern U. parryii from 21 locations across western Beringia, provided no support for earlier proposals that ancient arctic ground squirrels from Siberia constitute a distinct species. In fact, we observed genetic continuity of the glacialis mitochondrial DNA lineage in modern U. parryii of the Kamchatka peninsula. When viewed in a broader geographic perspective, our findings provide new insights into the genetic history of U. parryii in Late Pleistocene Beringia. PMID:28205612

  8. One plus one: Binary alarm calls retain individual signature for longer periods than single-note alarms in the European ground squirrel (Spermophilus citellus).

    PubMed

    Schneiderová, Irena; Volodina, Elena V; Matrosova, Vera A; Volodin, Ilya A

    2017-02-20

    Ground squirrels emit species-specific alarm calls that, among other characteristics, differ by the number of elements. Unlike some species that produce single-element calls, e.g., the Speckled ground squirrel (Spermophilus suslicus), individual European ground squirrels (S. citellus) frequently emit binary-element calls in addition to single-element calls. We tested the hypothesis that the time stability of individuality encoded in alarm calls might be better retained by complicating their acoustic structure by adding extra elements. In a semi-captive colony of individually marked European ground squirrels, we repeatedly recorded alarm calls that were produced towards a human by 12 adult (2 males and 10 females) live-trapped animals. Repeated recordings occurred within time spans of a few hours, 2days and 1year from the first recording. Our results showed that individual calls were highly similar within recordings, but less similar between recordings separated by time spans. Individual differences were best retained when we used nine acoustic variables from both elements. The differences were worse when we used nine variables from only the first element and worst when we used nine variables from only the second element. These results supported the caller reliability hypothesis for species that produce multiple-note alarms, e.g., the Richardson's ground squirrel (S. richardsonii).

  9. Energetic costs of parasitism in the Cape ground squirrel Xerus inauris

    PubMed Central

    Scantlebury, M; Waterman, J.M; Hillegass, M; Speakman, J.R; Bennett, N.C

    2007-01-01

    Parasites have been suggested to influence many aspects of host behaviour. Some of these effects may be mediated via their impact on host energy budgets. This impact may include effects on both energy intake and absorption as well as components of expenditure, including resting metabolic rate (RMR) and activity (e.g. grooming). Despite their potential importance, the energy costs of parasitism have seldom been directly quantified in a field setting. Here we pharmacologically treated female Cape ground squirrels (Xerus inauris) with anti-parasite drugs and measured the change in body composition, the daily energy expenditure (DEE) using doubly labelled water, the RMR by respirometry and the proportions of time spent looking for food, feeding, moving and grooming. Post-treatment animals gained an average 19 g of fat or approximately 25 kJ d−1. DEE averaged 382 kJ d−1 prior to and 375 kJ d−1 post treatment (p>0.05). RMR averaged 174 kJ d−1 prior to and 217 kJ d−1 post treatment (p<0.009). Post-treatment animals spent less time looking for food and grooming, but more time on feeding. A primary impact of infection by parasites could be suppression of feeding behaviour and, hence, total available energy resources. The significant elevation of RMR after treatment was unexpected. One explanation might be that parasites produce metabolic by-products that suppress RMR. Overall, these findings suggest that impacts of parasites on host energy budgets are complex and are not easily explained by simple effects such as stimulation of a costly immune response. There is currently no broadly generalizable framework available for predicting the energetic consequences of parasitic infection. PMID:17613450

  10. Ecological and hormonal correlates of antipredator behavior in adult Belding’s ground squirrels (Spermophilus beldingi)

    PubMed Central

    2010-01-01

    Predator–prey relationships provide an excellent opportunity to study coevolved adaptations. Decades of theoretical and empirical research have illuminated the various behavioral adaptations exhibited by prey animals to avoid detection and capture, and recent work has begun to characterize physiological adaptations, such as immune reactions, metabolic changes, and hormonal responses to predators or their cues. A 2-year study quantified the activity budgets and antipredator responses of adult Belding’s ground squirrels (Spermophilus beldingi) living in three different California habitats and likely experiencing different predation pressures. At one of these sites, which is visually closed and predators and escape burrows are difficult to see, animals responding to alarm calls remain alert longer and show more exaggerated responses than adults living in two populations that likely experience less intense predation pressure. They also spend more time alert and less time foraging than adults at the other two sites. A 4-year study using noninvasive fecal sampling of cortisol metabolites revealed that S. beldingi living in the closed site also have lower corticoid levels than adults at the other two sites. The lower corticoids likely reflect that predation risk at this closed site is predictable, and might allow animals to mount large acute cortisol responses, facilitating escape from predators and enhanced vigilance while also promoting glucose storage for the approaching hibernation. Collectively, these data demonstrate that local environments and perceived predation risk influence not only foraging, vigilance, and antipredator behaviors, but adrenal functioning as well, which may be especially important for obligate hibernators that face competing demands on glucose storage and mobilization. PMID:20336174

  11. Characterization of adipocyte stress response pathways during hibernation in thirteen-lined ground squirrels.

    PubMed

    Rouble, Andrew N; Tessier, Shannon N; Storey, Kenneth B

    2014-08-01

    To avoid the harsh conditions of winter climates, hibernating mammals undergo a systematic depression of physiological function by reducing their metabolic rate. During this process, hibernators are exposed to significant stresses (e.g., low body temperature, ischemia-reperfusion) that must be dealt with appropriately to avoid irreversible tissue damage. Consequently, we investigated the contribution of stress-responsive antioxidant enzymes, heat shock proteins, signal transduction pathways (e.g., mitogen-activated protein kinases, MAPK), and transcription factors for their role in conferring tolerance to stress in the hibernating thirteen-lined ground squirrel (Ictidomys tridecemlineatus). Using a combination of multiplex protein panels and traditional immunoblotting procedures, we have focused on these stress factors in brown adipose tissue (BAT) and white adipose tissue (WAT) over cycles of torpor-arousal since they provide the means for heat production as a result of non-shivering thermogenesis and the mobilization of critical energy reserves, respectively. We show the differential and tissue-specific regulation of stress factors including a unified upregulation of the antioxidant enzyme Thioredoxin 1 in both tissues, an upregulation of superoxide dismutase (SOD1 and SOD2) in WAT, and an increase in heat shock proteins during the transitory periods of the torpor-arousal cycle (HSP90α in BAT and HSP60 in WAT). Additionally, an upregulation of the active form of ERK1/2 and p38 in BAT and select transcription factors (e.g., CREB-1 and ELK-1) in both tissues were identified. These data provide us with greater insight into the molecular mechanisms responsible for this animal's natural stress tolerance and outline molecular signatures which define stress resistance.

  12. [Disproportionate eruption of maxillary and mandibular incisors in the long-tailed ground squirrel].

    PubMed

    Klevezal', G A; Potapova, E G

    2010-01-01

    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. Correlation between the eruption rates of the maxillary and mandibular incisors typical for rodents is found in yearlings and some animals after hibernation. The eruption rate of the mandibular incisors is higher than the eruption rate of the maxillary incisors and can be taken as proportional to their length. In individuals that have hibernated and show proportional eruption of the incisors, the proportion of the total length of the incisor formed before and after hibernation is equal for the maxillary and mandibular incisors. In the individuals that have hibernated and show the correlation of the total length of the maxillary and mandibular incisors typical for rodents, the eruption rate of the mandibular incisor is equal to or less than the eruption rate of the maxillary incisor and the proportion of the incisor formed before hibernation is greater in the mandibular incisor than in the maxillary. This disproportionate pattern of incisor eruption is not typical for rodents and is a result of inequal grinding of the maxillary and mandibular incisors, which ultimately results in the normal ratio of the total length of the maxillary and mandibular incisors.

  13. Developmental and geographic variation in stress hormones in wild Belding’s ground squirrels (Spermophilus beldingi)

    PubMed Central

    Mateo, Jill M.

    2010-01-01

    Extensive research has been conducted on the role of glucocorticoids in regulating growth, mobilizing energy, responding to stressors and modulating learning and memory. However, little is known about the production of corticoids during early development in free-living animals, particularly during sensitive periods of acquisition of important behaviors. In a four-year study of Belding’s ground squirrels, Spermophilus beldingi, a non-invasive assay of glucocorticoids was used to quantify age and population differences among juveniles from three California locations. Fecal–cortisol metabolites are elevated during a short period when juveniles first emerge aboveground from their natal burrows at about 4 weeks of age. This period of cortisol elevation coincides with when young are learning survival behaviors such as anti-predator responses and foraging strategies. Population differences in juvenile cortisol levels, which may reflect local variation in habitat quality and predator environments, were not evident until 2 weeks after emergence. Elevated cortisol at the age of emergence was also observed in juveniles born and reared in captivity without exposure to typical stressors that occur around the age of emergence. These results indicate that corticoids are regulated during early development, and the possible functions of age-related corticoid levels are discussed, including mobilization of glucose for natal emergence and later facilitation of growth and energy storage during the short summer before hibernation. In some species, elevated corticoids can also facilitate learning and memory, and current work is exploring whether the higher cortisol observed in all three S. beldingi populations just after emergence function to promote rapid acquisition of survival behaviors. PMID:16890229

  14. Purification and properties of glycerol-3-phosphate dehydrogenase from the liver of the hibernating ground squirrel, Urocitellus richardsonii.

    PubMed

    Ruberto, Anthony A; Childers, Christine L; Storey, Kenneth B

    2016-12-01

    Cytosolic glycerol-3-phosphate dehydrogenase (G3PDH, EC 1.1.1.8) is an important branch point enzyme connecting lipid metabolism and carbohydrate metabolism. We investigated the dynamic nature of G3PDH by purifying the enzyme from the liver of Richardson's ground squirrel (Urocitellus richardsonii), a hibernating species, and analyzing its structural and functional changes during hibernation. Kinetic parameters of purified G3PDH from ground squirrel liver were characterized at 37, 22 and 5°C and compared between euthermic and hibernating states. Relative to euthermic liver G3PDH, hibernator liver G3PDH had a decreased affinity for its substrate, glycerol-3-phosphate (G3P), at 37°C and 22°C. However, at 5°C, there was a significant increase in the affinity for G3P in the hibernating form of the enzyme, relative to the euthermic form. Furthermore, the structure of G3PDH in the species' hibernating state showed greater thermal stability compared to its structure in the euthermic state. Western blot analysis revealed greater tyrosine phosphorylation in hibernator G3PDH as compared to euthermic G3PDH. In addition, using the protein sequence of the hibernating thirteen-lined ground squirrel (Ictidomys tridecemlineatus) and bioinformatics tools, a three-dimensional model of G3PDH was built to identify the potential phosphorylation site ((83)Tyr) responsible for the differential phosphorylation between euthermic and hibernator G3PDH. The structural and functional changes in G3PDH support the enzyme's function at a low core body temperature experienced during the species hibernating season.

  15. Winter body temperature patterns in free-ranging Cape ground squirrel, Xerus inauris: no evidence for torpor.

    PubMed

    Wilson, Wendy A; O'Riain, M Justin; Hetem, Robyn S; Fuller, Andrea; Fick, Linda G

    2010-10-01

    The body temperature (T(b)) of Cape ground squirrels (Xerus inauris, Sciuridae) living in their natural environment during winter has not yet been investigated. In this study we measured abdominal T(b) of eight free-ranging Cape ground squirrels over 27 consecutive days during the austral winter. Mean daily T(b) was relatively stable at 37.0 ± 0.2°C (range 33.4 to 40.2°C) despite a marked variation in globe temperature (T(g)) (range -7 to 37°C). Lactating females (n = 2) consistently had a significantly higher mean T (b) (0.7°C) than non-lactating females (n = 3) and males. There was a pronounced nychthemeral rhythm with a mean active phase T(b) of 38.1 ± 0.1°C and a mean inactive phase T(b) of 36.3 ± 0.3°C for non-lactating individuals. Mean daily amplitude of T(b) rhythm was 3.8 ± 0.2°C. T(b) during the active phase closely followed T(g) and mean active phase T(b) was significantly correlated with mean active phase T(g) (r(2) = 0.3-0.9; P < 0.01). There was no evidence for daily torpor or pronounced hypothermia during the inactive phase, and mean minimum inactive phase T(b) was 35.7 ± 0.3°C for non-lactating individuals. Several alternatives (including nocturnal huddling, an aseasonal breeding pattern and abundant winter food resources) as to why Cape ground squirrels do not employ nocturnal hypothermia are discussed.

  16. Coping with intense reproductive aggression in male arctic ground squirrels: the stress axis and its signature tell divergent stories.

    PubMed

    Delehanty, Brendan; Boonstra, Rudy

    2011-01-01

    We tested the adaptive stress hypothesis that male arctic ground squirrels (Urocitellus parryii) exhibit a stress response over the course of the breeding season that is characterized by increasing free cortisol concentrations, increasing mobilization of stored energy, and decreasing physical condition. We assessed the functioning of the hypothalamic-pituitary-adrenal axis by measuring cortisol levels in response to the stress of capture and in response to a hormone challenge protocol (dexamethasone suppression and adrenocorticotropic hormone stimulation). We measured blood glucose levels, free fatty acids, white blood cells, and hematocrit to assess the downstream physiological responses to cortisol. Immediately after spring emergence, male arctic ground squirrels had ample free abdominal fat and few signs of wounding. By the end of the breeding season 3 wk later, visible fat reserves were almost entirely gone, and most males had extensive wounds. Total plasma cortisol concentrations increased over this period, but so did corticosteroid-binding capacity, resulting in no change in the free cortisol response to capture. We found no significant changes in how the animals responded to our hormone challenges, contrary to our prediction that the stress axis should increase free cortisol production. Even though we found no change in the functioning of the stress axis, all of the downstream measures suggested that male arctic ground squirrels are chronically exposed to high cortisol concentrations. Over the breeding season, blood glucose increased, fat stores and circulating free fatty acids were depleted, and both hematocrit levels and white blood cell counts decreased significantly. Our data suggest that a more complex relationship between the stress axis and downstream measures of stress exists than that proposed by the adaptive stress hypothesis. We propose several nonexclusive, testable mechanisms that could explain our observations.

  17. [Oxidative modification of proteins and antioxidative blood activity of ground squirrels during induced awakening from winter sleep].

    PubMed

    Astaeva, M D; Klichkhanov, N K

    2009-01-01

    The intensity of oxidative modification of plasma proteins and activity of the antioxidative system of the blood of the ground squirrels during awakening from winter sleep is studied. During waking of animals, processes of oxidative modification of proteins in the blood plasma intensify. While the body temperature rises, the antioxidative activity of hydrophylic components of the blood plasma grows essentially, and erythrocyte superoxide dismutase too. Activity of erythrocyte catalase at all stages of waking is definitely higher than in the control. The received results evidence that the high activity of various links of antioxidative blood protection provides stability to oxidative stress during waking of animals from deep sleep.

  18. A refined technique for sciatic denervation in a golden-mantled ground squirrel (Callospermophilus lateralis) model of disuse atrophy.

    PubMed

    Sarukhanov, Valeri; Van Andel, Roger; Treat, Michael D; Utz, Jenifer C; van Breukelen, Frank

    2014-06-01

    Disuse atrophy of both muscle and bone can occur rapidly during periods of inactivity. In several rodent models developed for the study of disuse atrophy, immobilization is induced by prolonged cage restraint, hind limb unloading, tenotomy, sciatic nerve block or sciatic denervation. In less tractable species such as wild-caught hibernating rodents, the sciatic denervation model is superior in terms of both animal welfare and applicability to the characteristics of natural cases of disuse atrophy. The authors describe a refined surgical approach to sciatic denervation in golden-mantled ground squirrels (Callospermophilus lateralis), a hibernating species, that improves animal welfare and reduces the incidence of post-operative complications such as autotomy.

  19. Spontaneous adenocarcinoma immunoreactive to cyclooxygenase-2 and transforming growth factor-beta1 in the buccal salivary gland of a Richardson's ground squirrel (Spermophilus richardsonii).

    PubMed

    Yamate, Jyoji; Yamamoto, Emi; Nabe, Mikoto; Kuwamura, Mitsuru; Fujita, Daisuke; Sasai, Hiroshi

    2007-10-01

    The ground squirrel is used as an experimental animal because of its unique biological nature. A 3-year-old female Richardson's ground squirrel developed a mass, 1.5 cm in diameter, in the buccal mucosa. The mass consisted of neoplastic epithelial cells showing acinar, ductular, intraductal papillary, solid, and lobular growth patterns; the cells were immunoreactive to cytokeratin, cyclooxygenase-2 (a marker of malignancy) and TGF-beta1. After resection, the tumor recurred with increased area having a solid or lobular pattern with little differentiation. This tumor was diagnosed as an adenocarcinoma arising from the buccal gland, the first case reported in the ground squirrel. A prominent desmoplastic reaction was present. The interstitial cells reacted to alpha-smooth muscle actin and vimentin, indicating a myofibroblastic nature, presumably induced by epithelial TGF-beta1.

  20. Arctic ground squirrel neuronal progenitor cells resist oxygen and glucose deprivation-induced death

    PubMed Central

    Drew, Kelly L; Wells, Matthew; McGee, Rebecca; Ross, Austin P; Kelleher-Andersson, Judith

    2016-01-01

    AIM: To investigate the influence of ischemia/reperfusion on arctic ground squirrel (AGS) neuronal progenitor cells (NPCs), we subjected these cultured cells to oxygen and glucose deprivation. METHODS: AGS NPCs were expanded and differentiated into NPCs and as an ischemia vulnerable control, commercially available human NPCs (hNPCs) were seeded from thawed NPCs. NPCs, identified by expression of TUJ1 were seen at 14-21 d in vitro (DIV). Cultures were exposed to control conditions, hypoxia, oxygen and glucose deprivation or glucose deprivation alone or following return to normal conditions to model reperfusion. Cell viability and death were assessed from loss of ATP as well as from measures of alamarBlue® and lactate dehydrogenase in the media and from counts of TUJ1 positive cells using immunocytochemistry. Dividing cells were identified by expression of Ki67 and phenotyped by double labeling with GFAP, MAP2ab or TUJ1. RESULTS: We report that when cultured in NeuraLife™, AGS cells remain viable out to 21 DIV, continue to express TUJ1 and begin to express MAP2ab. Viability of hNPCs assessed by fluorescence alamarBlue (arbitrary units) depends on both glucose and oxygen availability [viability of hNPCs after 24 h oxygen glucose deprivation (OGD) with return of oxygen and glucose decreased from 48151 ± 4551 in control cultures to 43481 ± 2413 after OGD, P < 0.05]. By contrast, when AGS NPCs are exposed to the same OGD with reperfusion at 14 DIV, cell viability assessed by alamarBlue increased from 165305 ± 11719 in control cultures to 196054 ± 13977 after OGD. Likewise AGS NPCs recovered ATP (92766 ± 6089 in control and 92907 ± 4290 after modeled reperfusion; arbitrary luminescence units), and doubled in the ratio of TUJ1 expressing neurons to total dividing cells (0.11 ± 0.04 in control cultures vs 0.22 ± 0.2 after modeled reperfusion, P < 0.05). Maintaining AGS NPCs for a longer time in culture lowered resistance to injury, however, did not impair

  1. Mitochondrial phylogeography of the European ground squirrel, Spermophilus citellus, yields evidence on refugia for steppic taxa in the southern Balkans.

    PubMed

    Krystufek, B; Bryja, J; Buzan, E V

    2009-08-01

    The spatial genetic structure of the European ground squirrel, a species characteristic of the short-grass steppe, was investigated on the basis of a 1140-bp cyt b gene sequence. The phylogeographical architecture of this species is expected to shed light on the putative long-term presence of the steppic ecosystem in south-eastern Europe and the evolutionary consequences of glacial cycles as forcing factors in speciation. Among 31 haplotypes, three highly divergent phylogenetic lineages (Southern, Northern and Jakupica) were recognized. This result suggests the past existence of an allopatric fragmentation event caused by effective biogeographical barriers. The Southern lineage consisted of the southernmost populations, those from Greece, Macedonia and European Turkey, and showed the highest divergence from all other samples. Haplotypes of the Northern lineage showed little geographical structure, with dispersal on both sides of the Danube River and in both of the two main geographical fragments of the species. The Jakupica lineage is a geographical isolate on a high plateau in central Macedonia. The estimated time for divergence of the Southern lineage (ca. 0.58 Mya) suggests the long-term persistence of a short-grass steppic refugium in the southern Balkans. Although the divergence between the Northern and Jakupica lineages occurred more recently (ca. 0.3 Mya), it still putatively predates two glacial cycles. The three phylogeographical lineages of the European ground squirrel should be regarded as independent units for conservation management purposes.

  2. Inhibition of Borna disease virus replication by an endogenous bornavirus-like element in the ground squirrel genome.

    PubMed

    Fujino, Kan; Horie, Masayuki; Honda, Tomoyuki; Merriman, Dana K; Tomonaga, Keizo

    2014-09-09

    Animal genomes contain endogenous viral sequences, such as endogenous retroviruses and retrotransposons. Recently, we and others discovered that nonretroviral viruses also have been endogenized in many vertebrate genomes. Bornaviruses belong to the Mononegavirales and have left endogenous fragments, called "endogenous bornavirus-like elements" (EBLs), in the genomes of many mammals. The striking features of EBLs are that they contain relatively long ORFs which have high sequence homology to the extant bornavirus proteins. Furthermore, some EBLs derived from bornavirus nucleoprotein (EBLNs) have been shown to be transcribed as mRNA and probably are translated into proteins. These features lead us to speculate that EBLs may function as cellular coopted genes. An EBLN element in the genome of the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), itEBLN, encodes an ORF with 77% amino acid sequence identity to the current bornavirus nucleoprotein. In this study, we cloned itEBLN from the ground squirrel genome and investigated its involvement in Borna disease virus (BDV) replication. Interestingly, itEBLN, but not a human EBLN, colocalized with the viral factory in the nucleus and appeared to affect BDV polymerase activity by being incorporated into the viral ribonucleoprotein. Our data show that, as do certain endogenous retroviruses, itEBLN potentially may inhibit infection by related exogenous viruses in vivo.

  3. Seasonal changes in spermatogenesis and immunolocalization of inhibin/activin subunits in the wild male ground squirrel (Citellus dauricus Brandt).

    PubMed

    Sheng, Xia; Zhang, Haolin; Zhang, Wei; Song, Moshi; Zhang, Mengyuan; Li, Ben; Weng, Qiang; Watanabe, Gen; Taya, Kazuyoshi

    2008-12-01

    The objective of this study was to investigate the seasonal changes in spermatogenesis and the immunolocalization of the inhibin alpha and inhibin/activin (betaA and betaB) subunits during the breeding and non-breeding seasons in the wild male ground squirrel. The testicular weight and size and seminiferous tubule diameter were measured, and histological observations of testes were performed. The sections of the testes were immunostained by the avidin-biotin-peroxidase complex method (ABC) using polyclonal antisera raised against porcine inhibin alpha, inhibin/activin betaA and inhibin/activin betaB during the breeding and non-breeding seasons. There were marked variations in testicular weight and size and seminiferous tubule diameter between the breeding and non-breeding seasons, and all types of spermatogenic cells, including spermatozoa, were found in the breeding season. In addition, immunoreactivity was also detected for the inhibin alpha, betaA and betaB subunits in Sertoli and Leydig cells during the breeding season, but immunostaining was only present for the inhibin alpha and inhibin/activin betaB subunits in Sertoli cells during the non-breeding season. These results suggest that seasonal changes in testicular weight and size and seminiferous tubule diameter of wild ground squirrels are correlated with changes in spermatogenesis, and the cellular localization of the inhibin/activin subunits showed season related changes in the breeding and non-breeding seasons.

  4. Inhibition of NMDA-type glutamate receptors induces arousal from torpor in hibernating arctic ground squirrels (Urocitellus parryii).

    PubMed

    Jinka, Tulasi R; Rasley, Brian T; Drew, Kelly L

    2012-09-01

    Hibernation is an adaptation to overcome periods of resource limitation often associated with extreme climatic conditions. The hibernation season consists of prolonged bouts of torpor that are interrupted by brief interbout arousals. Physiological mechanisms regulating spontaneous arousals are poorly understood, but may be related to a need for gluconeogenesis or elimination of metabolic wastes. Glutamate is derived from glutamine through the glutamate-glutamine cycle and from glucose via the pyruvate carboxylase pathway when nitrogen balance favors formation of glutamine. This study tests the hypothesis that activation of NMDA-type glutamate receptors (NMDAR) maintains torpor in arctic ground squirrel (arctic ground squirrel (AGS); Urocitellus parryii). Administration of NMDAR antagonists MK-801 (5 mg/kg, i.p.) that crosses the blood-brain barrier and AP5 (5 mg/kg, i.p.) that does not cross the blood-brain barrier induced arousal in AGS. Central administration of MK-801 (0.2, 2, 20 or 200 μg; icv) to hibernating AGS failed to induce arousal. Results suggest that activation of NMDAR at a peripheral or circumventricular site is necessary to maintain prolonged torpor and that a decrease in glutamate at these sites may contribute to spontaneous arousal in AGS.

  5. Inhibition of Borna disease virus replication by an endogenous bornavirus-like element in the ground squirrel genome

    PubMed Central

    Fujino, Kan; Horie, Masayuki; Honda, Tomoyuki; Merriman, Dana K.; Tomonaga, Keizo

    2014-01-01

    Animal genomes contain endogenous viral sequences, such as endogenous retroviruses and retrotransposons. Recently, we and others discovered that nonretroviral viruses also have been endogenized in many vertebrate genomes. Bornaviruses belong to the Mononegavirales and have left endogenous fragments, called “endogenous bornavirus-like elements” (EBLs), in the genomes of many mammals. The striking features of EBLs are that they contain relatively long ORFs which have high sequence homology to the extant bornavirus proteins. Furthermore, some EBLs derived from bornavirus nucleoprotein (EBLNs) have been shown to be transcribed as mRNA and probably are translated into proteins. These features lead us to speculate that EBLs may function as cellular coopted genes. An EBLN element in the genome of the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), itEBLN, encodes an ORF with 77% amino acid sequence identity to the current bornavirus nucleoprotein. In this study, we cloned itEBLN from the ground squirrel genome and investigated its involvement in Borna disease virus (BDV) replication. Interestingly, itEBLN, but not a human EBLN, colocalized with the viral factory in the nucleus and appeared to affect BDV polymerase activity by being incorporated into the viral ribonucleoprotein. Our data show that, as do certain endogenous retroviruses, itEBLN potentially may inhibit infection by related exogenous viruses in vivo. PMID:25157155

  6. Activity of Ca2+-dependent neutral proteases in tissues of ground squirrel during hibernation and during self-warming after induced awakening.

    PubMed

    Nurmagomedova, P M; Abasova, M M; Emirbekov, E Z

    2011-09-01

    Cyclic changes in activity of Ca2+-dependent neutral protease occur during preparation for hibernation, with an increase in September and November and decrease in October and December. During hibernation proteolytic enzyme activity decreased, while during self-warming after induced awakening, the role of Ca2+-dependent processes in the tissues of ground squirrels increased according to the body temperature.

  7. Differences in alarm calls of juvenile and adult European ground squirrels (Spermophilus citellus): Findings on permanently marked animals from a semi-natural enclosure.

    PubMed

    Schneiderov, Irena; Schnitzerov, Petra; Uhlikov, Jitka; Brandl, Pavel; Zouhar, Jan; Matejů, Jan

    2015-11-01

    The European ground squirrel (Spermophilus citellus) emits alarm calls that warn conspecifics of potential danger. Although it has been observed that inexperienced juveniles of this species emit alarm calls that sound similar to those of adults, studies focusing on juvenile alarm calls are lacking. We analyzed the acoustic structure of alarm calls emitted by six permanently marked European ground squirrels living in a semi-natural enclosure when they were juveniles and after 1 year as adults. We found that the acoustic structure of the juvenile alarm calls was significantly different from those of adults and that the alarm calls underwent nearly the same changes in all studied individuals. All juveniles emitted alarm calls consisting of one element with almost constant frequency, but their alarm calls included a second frequency-modulated element after their first hibernation as adults. Our data show that the duration of the first element is significantly shorter in adults than in juveniles. Additionally, the frequency of the first element is significantly higher in adults than in juveniles. Similar to previous findings in other Palearctic ground squirrel species, our data are inconsistent with the assumption that juvenile mammals emit vocalizations with higher fundamental frequencies than adults. However, our results do not support the previously suggested hypothesis that juvenile ground squirrels conceal information regarding their age in their alarm calls because we found significant differences in alarm calls of juveniles and adults.

  8. Daily body temperature rhythms persist under the midnight sun but are absent during hibernation in free-living arctic ground squirrels.

    PubMed

    Williams, Cory T; Barnes, Brian M; Buck, C Loren

    2012-02-23

    In indigenous arctic reindeer and ptarmigan, circadian rhythms are not expressed during the constant light of summer or constant dark of winter, and it has been hypothesized that a seasonal absence of circadian rhythms is common to all vertebrate residents of polar regions. Here, we show that, while free-living arctic ground squirrels do not express circadian rhythms during the heterothermic and pre-emergent euthermic intervals of hibernation, they display entrained daily rhythms of body temperature (T(b)) throughout their active season, which includes six weeks of constant sun. In winter, ground squirrels are arrhythmic and regulate core body temperatures to within ±0.2°C for up to 18 days during steady-state torpor. In spring, after the use of torpor ends, male but not female ground squirrels, resume euthermic levels of T(b) in their dark burrows but remain arrhythmic for up to 27 days. However, once activity on the surface begins, both sexes exhibit robust 24 h cycles of body temperature. We suggest that persistence of nycthemeral rhythms through the polar summer enables ground squirrels to minimize thermoregulatory costs. However, the environmental cues (zeitgebers) used to entrain rhythms during the constant light of the arctic summer in these semi-fossorial rodents are unknown.

  9. Within-individual correlations reveal link between a behavioral syndrome, condition and cortisol in free-ranging Belding's ground squirrels

    PubMed Central

    Brooks, Katherine C.; Mateo, Jill. M.

    2014-01-01

    Animals often exhibit consistent individual differences in behavior (i.e. animal personality) and correlations between behaviors (i.e. behavioral syndromes), yet the causes of those patterns of behavioral variation remain insufficiently understood. Many authors hypothesize that state-dependent behavior produces animal personality and behavioral syndromes. However, empirical studies assessing patterns of covariation among behavioral traits and state variables have produced mixed results. New statistical methods that partition correlations into between-individual and residual within-individual correlations offer an opportunity to more sufficiently quantify relationships among behaviors and state variables to assess hypotheses of animal personality and behavioral syndromes. In a population of wild Belding's ground squirrels (Urocitellus beldingi) we repeatedly measured activity, exploration, and response to restraint behaviors alongside glucocorticoids and nutritional condition. We used multivariate mixed models to determine whether between-individual or within-individual correlations drive phenotypic relationships among traits. Squirrels had consistent individual differences for all five traits. At the between-individual level, activity and exploration were positively correlated whereas both traits negatively correlated with response to restraint, demonstrating a behavioral syndrome. At the within-individual level, condition negatively correlated with cortisol, activity and exploration. Importantly, this indicates that although behavior is state-dependent, which may play a role in animal personality and behavioral syndromes, feedback mechanisms between condition and behavior appear not to produce consistent individual differences in behavior and correlations between them. PMID:25598565

  10. Sexing the Sciuridae: a simple and accurate set of molecular methods to determine sex in tree squirrels, ground squirrels and marmots.

    PubMed

    Gorrell, Jamieson C; Boutin, Stan; Raveh, Shirley; Neuhaus, Peter; Côté, Steeve D; Coltman, David W

    2012-09-01

    We determined the sequence of the male-specific minor histocompatibility complex antigen (Smcy) from the Y chromosome of seven squirrel species (Sciuridae, Rodentia). Based on conserved regions inside the Smcy intron sequence, we designed PCR primers for sex determination in these species that can be co-amplified with nuclear loci as controls. PCR co-amplification yields two products for males and one for females that are easily visualized as bands by agarose gel electrophoresis. Our method provides simple and reliable sex determination across a wide range of squirrel species.

  11. [Possible reasons for the variability of the inotropic insulin effect in papillary muscles of ground squirrel myocardium].

    PubMed

    Nakipova, O V; Chumaeva, L A; Andreeva, L A; Anufriev, A I; Kukushkin, N I

    2012-01-01

    The effects of insulin (0.1-50 nM) on isometric twitch force (0.1 to 1.0 Hz; 30 +/- 1 degree C; 1.8 mM Ca(2+)) were studied in right ventricular papillary muscles from active ground squirrels of different seasons (summer, n = 14; autumn, n = 16 and winter interbout, n = 16) in control conditions and after one-hour pretreatment of PM with 2 mkM nifedipine (an L-type Ca(2+)-channel inhibitor) and 1.0 mM orthovanadate (a tyrosine phosphatase inhibitor). In active animals of different seasonal periods insulin causes both positive and negative inotropic effects. At low frequencies (0.1-0.5 Hz), insulin of low concentrations (0.1-1.0 nM) induces a transient (within the first 20 min after application) positive effect (about 15-25%). Application of high hormone concentration (10 nM) in a low range of stimulation frequencies causes a biphasic effect (a small initial positive inotropic effect followed by a marked negative one). At frequencies above 0.5-Hz stimulation, insulin of 10 nM concentration causes presumably a negative inotropic effect. It was proposed that ICaL is possibly involved in the insulin-induced negative inotropy in ground squirrels hearts. Alteration of protein phosphorylation in tyrosine residues is known to be a major link in the mechanism of insulin action. We performed a study on orthovanadate action (a known inhibitor of tyrosine phosphatase) on the inotropic insulin effect. In the group of summer animals the pretreatment of papillary muscles with orthovanadate (100 mkM) does not change the negative inotropic effect of insulin in a low range of stimulation frequencies but almost completely removes this effect at stimulation frequencies above 0.3 Hz (n = 4). Nifedipine (1-1.5 hr pretreatment), a blocker of L-type calcium channel, reduces the inhibitory effect of insulin in autumn and winter animals, and on the contrary intensifies it in summer animals. This fact indicates that different mechanisms must be involved in insulin actions in animals of

  12. How will the greening of the Arctic affect an important prey species and disturbance agent? Vegetation effects on arctic ground squirrels.

    PubMed

    Wheeler, H C; Chipperfield, J D; Roland, C; Svenning, J-C

    2015-07-01

    Increases in terrestrial primary productivity across the Arctic and northern alpine ecosystems are leading to altered vegetation composition and stature. Changes in vegetation stature may affect predator-prey interactions via changes in the prey's ability to detect predators, changes in predation pressure, predator identity and predator foraging strategy. Changes in productivity and vegetation composition may also affect herbivores via effects on forage availability and quality. We investigated if height-dependent effects of forage and non-forage vegetation determine burrowing extent and activity of arctic ground squirrels (Urocitellus parryii). We collected data on burrow networks and activity of arctic ground squirrels across long-term vegetation monitoring sites in Denali National Park and Preserve, Alaska. The implications of height-specific cover of potential forage and non-forage vegetation on burrowing behaviour and habitat suitability for arctic ground squirrels were investigated using hierarchical Bayesian modelling. Increased cover of forbs was associated with more burrows and burrow systems, and higher activity of systems, for all forb heights. No other potential forage functional group was related to burrow distribution and activity. In contrast, height-dependent negative effects of non-forage vegetation were observed, with cover over 50-cm height negatively affecting the number of burrows, systems and system activity. Our results demonstrate that increases in vegetation productivity have dual, potentially counteracting effects on arctic ground squirrels via changes in forage and vegetation stature. Importantly, increases in tall-growing woody vegetation (shrubs and trees) have clear negative effects, whereas increases in forb should benefit arctic ground squirrels.

  13. Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia-normothermia in vivo: A three-dimensional electron microscope study.

    PubMed

    Popov, V I; Medvedev, N I; Patrushev, I V; Ignat'ev, D A; Morenkov, E D; Stewart, M G

    2007-11-09

    A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2-4 degrees C), or after warming and recovery to the normothermic state (34 degrees C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 degrees C at which time core rectal temperature was 15 degrees C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal.

  14. In vitro and in vivo thermal activation of steroid-receptor complexes from rats and ground squirrels (Spermophilus citellus).

    PubMed

    Zivadinović, D; Andjus, R K

    1995-02-01

    Using 3H-labelled triamcinolone acetonide (3HTA, synthetic steroid hormone), it was shown that the in vitro time course kinetics of thermal activation of 3HTA-receptor complexes exhibited the same temperature dependence in liver cytosols prepared from hibernating ground squirrels (Spermophilus citellus) as in cytosols from the rat. When 3HTA was injected in vivo to animals hibernating with a body temperature of 3 degrees C, the activation and nuclear uptake of the in vivo formed steroid-receptor complexes proceeded at a slow rate, comparable to the one predicted by in vitro studies. In the hibernator, the results are not indicative of adaptive modifications at the level of thermal activation, but prove that steroid action does proceed at a temperature incompatible with hypothermic survival in the nonhibernator.

  15. Metabolic hormone FGF21 is induced in ground squirrels during hibernation but its overexpression is not sufficient to cause torpor.

    PubMed

    Nelson, Bethany T; Ding, Xunshan; Boney-Montoya, Jamie; Gerard, Robert D; Kliewer, Steven A; Andrews, Matthew T

    2013-01-01

    Hibernation is a natural adaptation that allows certain mammals to survive physiological extremes that are lethal to humans. Near freezing body temperatures, heart rates of 3-10 beats per minute, absence of food consumption, and depressed metabolism are characteristic of hibernation torpor bouts that are periodically interrupted by brief interbout arousals (IBAs). The molecular basis of torpor induction is unknown, however starved mice overexpressing the metabolic hormone fibroblast growth factor 21 (FGF21) promote fat utilization, reduce body temperature, and readily enter torpor-all hallmarks of mammalian hibernation. In this study we cloned FGF21 from the naturally hibernating thirteen-lined ground squirrel (Ictidomys tridecemlineatus) and found that levels of FGF21 mRNA in liver and FGF21 protein in serum are elevated during hibernation torpor bouts and significantly elevated during IBAs compared to summer active animals. The effects of artificially elevating circulating FGF21 concentrations 50 to 100-fold via adenoviral-mediated overexpression were examined at three different times of the year. This is the first time that a transgenic approach has been used in a natural hibernator to examine mechanistic aspects of hibernation. Surgically implanted transmitters measured various metrics of the hibernation phenotype over a 7-day period including changes in motor activity, heart rate and core body temperature. In April fed-state animals, FGF21 overexpression decreased blood insulin and free fatty acid concentrations, effects similar to those seen in obese mice. However, elevated FGF21 concentrations did not cause torpor in these fed-state animals nor did they cause torpor or affect metabolic parameters in fasted-state animals in March/April, August or October. We conclude that FGF21 is strongly regulated during torpor and IBA but that its overexpression is not sufficient to cause torpor in naturally hibernating ground squirrels.

  16. Isolation and identification of a snake venom metalloproteinase inhibitor from California ground squirrel (Spermophilus beecheyi) blood sera.

    PubMed

    Biardi, J E; Ho, C Y L; Marcinczyk, J; Nambiar, K P

    2011-11-01

    California ground squirrels (Spermophilus beecheyi) show blood-based defenses to a variety of toxins in the venom of the Northern Pacific rattlesnake (Crotalus oreganus oreganus). In this study we demonstrate the presence of an effective snake venom metalloproteinase inhibitor (SVMPI) in S. beecheyi. The blood sera of California ground squirrels were effective at reducing the metalloproteinase activity of Northern Pacific (C. o. oreganus) and prairie rattlesnake (Crotalus viridis viridis) venoms by over 75%, significantly more than its ability to reduce the activity of western diamondback rattlesnake venom. We used anion exchange and affinity chromatography to isolate this protein from the blood sera of S. beecheyi. This SVMPI had a molecular mass of 108.3 kDa and a pI of 5.1. The IC(50) of this inhibitor against whole venom from C. o. oreganus was determined to be 3.14 × 10(-8) M. Subsequent LC MS/MS analysis of a CNBr/tryptic digest of the inhibitor yielded multiple internal peptide sequences. These sequences showed homology to three other known mammalian plasma proteins: inter-α trypsin inhibitor, and two hibernation-associated proteins, HP25 and HP27. The presence of SVMPI in S. beecheyi blood sera is consistent with the resistance of these animals to venom-induced hemorrhage and tissue damage, and consistent with the protective factors conferring venom resistance in other mammals. However, the variety of SVMPI identified to date from mammalian taxa suggests that different species have converged on neutralization of venom metalloproteinase activity as a key step in venom neutralization.

  17. State-dependent variation in the inhibitory effect of (D-Ala sup 2 , D-Leu sup 5 )-enkephalin on hippocampal serotonin release in ground squirrels

    SciTech Connect

    Kramarova, L.I.; Lee, T.F.; Cui, Y.; Wang, L.C.H. )

    1990-01-01

    Accumulated evidence has suggested that increased endogenous opioid activities may facilitate the onset of hibernation either directly or possibly through modulation of other neurotransmitter systems. The seasonal change of (D-Ala{sup 2}, D-Leu{sup 5})-enkephalin (DADLE), a {delta} receptor agonist, in modulating K{sup +}-induced ({sup 3}H)-5-hydroxytryptamine (5-HT) release from the hippocampal and hypothalamic slices of euthermic and hibernating Richardsons' ground squirrels was therefore investigated. DADLE had no effect on 5-HT release in the hypothalamic slices but elicited a dose-related inhibition on ({sup 3}H)-5-HT release from the hippocampal slices of the euthermic ground squirrel. The inhibitory effect of DADLE was completely reversed by naloxone, but not by tetrodotoxin. In contrast, DADLE failed to alter the K{sup +}-induced 5-HT release from the hippocampal slices of the hibernating ground squirrel. This state-dependent reduction in responsiveness to an opioid is consistent with the hypothesis that enhanced endogenous opioid activity in the hibernating phase could lead to down regulation of the opioid receptors and minimize its inhibition on hippocampal serotonergic activity. A high 5-HT activity would inhibit midbrain reticular activating system indirectly through non-serotonergic fibers, which in turn facilitate the onset or maintenance of hibernation.

  18. Seasonal Changes of Androgen Receptor, Estrogen Receptors and Aromatase Expression in the Medial Preoptic Area of the Wild Male Ground Squirrels (Citellus Dauricus Brandt)

    PubMed Central

    Zhang, F.; Wang, J.; Jiao, Y.; Zhang, L.; Zhang, H.; Sheng, X.; Han, Y.; Yuan, Z.; Weng, Q.

    2016-01-01

    The wild ground squirrel is a typical seasonal breeder. In this study, using RT-PCR, western blot and immunohistochemistry, we investigated the mRNA and protein expressions of androgen receptor (AR), estrogen receptors a and β (ERα and ERβ) and aromatase cytochrome P450 (P450arom) in the medial preoptic area (MPOA) of hypothalamus of the wild male ground squirrel during the breeding season (April), the non-breeding season (June) and pre-hibernation (September). AR, ERα, ERβ and P450arom protein/mRNA were present in the MPOA of all seasons detected. The immunostaining of AR and ERα showed no significant changes in different periods, whereas ERβ and P450arom had higher immunoreactivities during the breeding season and pre-hibernation when compared to those of the non-breeding season. Consistently, both the protein and mRNA levels of P450arom and ERβ were higher in the MPOA of pre-hibernation and the breeding season than in the non-breeding season, whereas no significant difference amongst the three periods was observed for AR and ERα levels. These findings suggested that the MPOA of hypothalamus may be a direct target of androgen and estrogen. Androgen may play important regulatory roles through its receptor and/or the aromatized estrogen in the MPOA of hypothalamus of the wild male ground squirrels. PMID:27349316

  19. Immunolocalization of NGF and its receptors in ovarian surface epithelium of the wild ground squirrel during the breeding and nonbreeding seasons.

    PubMed

    Bao, L; Li, Q; Liu, Y; Li, B; Sheng, X; Han, Y; Weng, Q

    2014-05-09

    The ovarian surface epithelium (OSE) plays an important role in normal ovarian physiology. During each reproductive cycle, the OSE takes part in the cyclical ovulatory ruptures and repair. The aim of this study was to investigate the immunolocalization of nerve growth factor (NGF) and its receptors, tyrosine kinase A (TrkA) and p75, in the OSE cells of the wild ground squirrels during the breeding and nonbreeding seasons. There were marked variations in ovarian weight and size between the breeding and the nonbreeding seasons. Histologically, cuboidal cells and squamous cells were identified in the OSE of both seasons. Yet, stronger immunostaining of NGF, TrkA and p75 were observed in cuboidal cells and squamous cells in the breeding season as compared to the nonbreeding season. In addition, plasma gonadotropin concentrations were higher in the breeding season than in the nonbreeding season, suggesting that the expression patterns of NGF, TrkA and p75 in the OSE were correlated with changes in plasma gonadotropins. These findings suggested that NGF and its receptor TrkA and p75 may be involved in the regulation of seasonal changes in the OSE of wild ground squirrel.in the OSE of wild ground squirrel.

  20. Estimating lean mass over a wide range of body composition: a calibration of deuterium dilution in the arctic ground squirrel.

    PubMed

    Lee, Trixie N; Fridinger, Robert W; Barnes, Brian M; Loren Buck, C; O'Brien, Diane M

    2011-12-15

    Calculating body water through isotope dilution has become a useful way to nondestructively estimate body composition in many species. The most accurate estimates using this method require calibration against proximate chemical analysis of body composition for individual species, but no studies to our knowledge have calibrated this method on a hibernating mammal that seasonally undergoes dramatic changes in body composition. We use deuterium oxide to estimate total body water in captive arctic ground squirrels, Urocitellus parryii, and compare two approaches of calculating lean mass from total body water, both calibrated against lean mass based on proximate analysis. The first method uses a single tissue hydration constant to calculate lean mass from total body water; the second method uses a predictive equation to calculate lean mass from total body water and body mass. We found that the predictive equation performs better over the large range of body composition common to this species. Distillation of blood samples did not affect lean mass estimates from either calculation method. These findings indicate that isotope dilution using a predictive equation should work well as an alternative to destructive methods in other small mammals that undergo radical changes in body composition across their annual cycle.

  1. Laboratory evaluation of fipronil and imidacloprid topical insecticides for control of the plague vector Oropsylla montana (Siphonaptera: Ceratophyllidae) on california ground squirrels (Rodentia: Sciuridae).

    PubMed

    Metzger, Marco E; Rust, Michael K

    2002-01-01

    Two insecticides, fipronil and imidacloprid, were evaluated for efficacy and longevity against Oropsylla montana (Baker), the most important vector of plague in California. Wild-caught California ground squirrels, Spermophilus beecheyi (Richardson), were individually housed in the laboratory to serve as natural hosts to O. montana and for on-animal insecticide trials. Several concentrations oftechnical grade fipronil and imidacloprid in acetone were applied to samples of clean rodent bedding to determine residual activity and longevity against fleas. Immature and adult cat fleas, Ctenocephalides felis (Bouche), were used as representative fleas for periodic assays in place of less fecund O. montana. Toxicity of treated bedding did not decrease significantly for 1 yr at all applied concentrations. Fipronil provided 100% kill for at least 1 yr at > or = 100 ppm, whereas imidacloprid required 10,000 ppm for similar performance. Laboratory squirrels were treated with topical formulations of fipronil (Frontline Top Spot) and imidacloprid (Advantage Flea Adulticide) at a dosage rate of 15 mg/kg and evaluated for residual activity every 2 wk against adult O. montana. Residual activity was determined by percent recovery of O. montana adults released on treated and untreated animals after 48 h. Frontline provided 100% kill of adult fleas for at least 10 wk, and up to 26 wk on one animal. Advantage failed to provide 100% kill of adult fleas at 2 wk, with complete loss of efficacy by week 6. Concurrent assays with bedding samples from squirrel nest boxes showed negligible toxicity transfer from treated animals to nest bedding.

  2. The expression of leptin, hypothalamic neuropeptides and UCP1 before, during and after fattening in the Daurian ground squirrel (Spermophilus dauricus).

    PubMed

    Xing, Xin; Yang, Ming; Wang, De-Hua

    2015-06-01

    The Daurian ground squirrel (Spermophilus dauricus) accumulates large amounts of body fat during pre-hibernation fattening. Leptin, an adipose-derived hormone, plays important roles in energy balance and thermogenesis. We predicted that body fat accumulation would lead to the elevation of leptin concentration while its effect on satiety would be suppressed in hypothalamus during fattening. In addition, the uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) would increase and correlated positively with leptin concentration before hibernation. Here, we measured serum leptin concentration and leptin mRNA in white adipose tissue (WAT), hypothalamic neuropeptides involved in energy regulation and UCP1 in BAT before, during and after fattening in squirrels. The fat mass gradually increased during fattening but serum leptin increased mainly in the late phase of fattening, which was consistent with leptin mRNA expression in WAT. During fattening, the mRNA of hypothalamic leptin receptor was up-regulated and correlated positively with serum leptin. Orexigenic neuropeptide Y mRNA increased by 67%; however agouti-related peptide remained unchanged before hibernation. There was no significant change in anorexigenic neuropeptide mRNA. No change in suppressor of cytokine signaling-3 and protein tyrosine phosphatase-1B was detected. UCP1 mRNA expression and protein content in BAT increased significantly after fattening. These changes were independent of environmental conditions and serum leptin concentration. Our results suggest that the dissociation of leptin production and adiposity during fattening may facilitate fat accumulation. No evidence of suppressed leptin signal was found in fattening squirrels. The UCP1 recruitment in post-fattening squirrels could occur without winter-like acclimation and increased leptin.

  3. The impact of cold acclimation and hibernation on antioxidant defenses in the ground squirrel (Spermophilus citellus): an update.

    PubMed

    Vucetic, Milica; Stancic, Ana; Otasevic, Vesna; Jankovic, Aleksandra; Korac, Aleksandra; Markelic, Milica; Velickovic, Ksenija; Golic, Igor; Buzadzic, Biljana; Storey, Kenneth B; Korac, Bato

    2013-12-01

    Any alteration in oxidative metabolism is coupled with a corresponding response by an antioxidant defense (AD) in appropriate subcellular compartments. Seasonal hibernators pass through circannual metabolic adaptations that allow them to either maintain euthermy (cold acclimation) or enter winter torpor with body temperature falling to low values. The present study aimed to investigate the corresponding pattern of AD enzyme protein expressions associated with these strategies in the main tissues involved in whole animal energy homeostasis: brown and white adipose tissues (BAT and WAT, respectively), liver, and skeletal muscle. European ground squirrels (Spermophilus citellus) were exposed to low temperature (4 ± 1 °C) and then divided into two groups: (1) animals fell into torpor (hibernating group) and (2) animals stayed active and euthermic for 1, 3, 7, 12, or 21 days (cold-exposed group). We examined the effects of cold acclimation and hibernation on the tissue-dependent protein expression of four enzymes which catalyze the two-step detoxification of superoxide to water: superoxide dismutase 1 and 2 (SOD 1 and 2), catalase (CAT), and glutathione peroxidase (GSH-Px). The results showed that hibernation induced an increase of AD enzyme protein expressions in BAT and skeletal muscle. However, AD enzyme contents in liver were largely unaffected during torpor. Under these conditions, different WAT depots responded by elevating the amounts of specific enzymes, as follows: SOD 1 in retroperitoneal WAT, GSH-Px in gonadal WAT, and CAT in subcutaneous WAT. Similar perturbations of AD enzymes contents were seen in all tissues during cold acclimation, often in a time-dependent manner. It can be concluded that BAT and muscle AD capacity undergo the most dramatic changes during both cold acclimation and hibernation, while liver is relatively unaffected by either condition. Additionally, this study provides a basis for further metabolic study that will illuminate the causes

  4. Lipid emulsion enhances cardiac performance after ischemia-reperfusion in isolated hearts from summer-active arctic ground squirrels.

    PubMed

    Salzman, Michele M; Cheng, Qunli; Deklotz, Richard J; Dulai, Gurpreet K; Douglas, Hunter F; Dikalova, Anna E; Weihrauch, Dorothee; Barnes, Brian M; Riess, Matthias L

    2017-03-31

    Hibernating mammals, like the arctic ground squirrel (AGS), exhibit robust resistance to myocardial ischemia/reperfusion (IR) injury. Regulated preference for lipid over glucose to fuel metabolism may play an important role. We tested whether providing lipid in an emulsion protects hearts from summer-active AGS better than hearts from Brown Norway (BN) rats against normothermic IR injury. Langendorff-prepared AGS and BN rat hearts were perfused with Krebs solution containing 7.5 mM glucose with or without 1% Intralipid™. After stabilization and cardioplegia, hearts underwent 45-min global ischemia and 60-min reperfusion. Coronary flow, isovolumetric left ventricular pressure, and mitochondrial redox state were measured continuously; infarct size was measured at the end of the experiment. Glucose-only AGS hearts functioned significantly better on reperfusion than BN rat hearts. Intralipid™ administration resulted in additional functional improvement in AGS compared to glucose-only and BN rat hearts. Infarct size was not different among groups. Even under non-hibernating conditions, AGS hearts performed better after IR than the best-protected rat strain. This, however, appears to strongly depend on metabolic fuel: Intralipid™ led to a significant improvement in return of function in AGS, but not in BN rat hearts, suggesting that year-round endogenous mechanisms are involved in myocardial lipid utilization that contributes to improved cardiac performance, independent of the metabolic rate decrease during hibernation. Comparative lipid analysis revealed four candidates as possible cardioprotective lipid groups. The improved function in Intralipid™-perfused AGS hearts also challenges the current paradigm that increased glucose and decreased lipid metabolism are favorable during myocardial IR.

  5. Circannual rhythm in body temperature, torpor, and sensitivity to A₁ adenosine receptor agonist in arctic ground squirrels.

    PubMed

    Olson, Jasmine M; Jinka, Tulasi R; Larson, Lindy K; Danielson, Jeffrey J; Moore, Jeanette T; Carpluck, Joanna; Drew, Kelly L

    2013-06-01

    A₁ adenosine receptor (A₁AR) activation within the central nervous system induces torpor, but in obligate hibernators such as the arctic ground squirrel (AGS; Urocitellus parryii), A₁AR stimulation induces torpor only during the hibernation season, suggesting a seasonal increase in sensitivity to A₁AR signaling. The purpose of this research was to investigate the relationship between body temperature (Tb) and sensitivity to an adenosine A1 receptor agonist in AGS. We tested the hypothesis that increased sensitivity in A₁AR signaling would lead to lower Tb in euthermic animals during the hibernation season when compared with the summer season. We further predicted that if a decrease in euthermic Tb reflects increased sensitivity to A₁AR activation, then it should likewise predict spontaneous torpor. We used subcutaneous IPTT-300 transponders to monitor Tb in AGS housed under constant ambient conditions (12:12 L:D, 18 °C) for up to 16 months. These animals displayed an obvious rhythm in euthermic Tb that cycled with a period of approximately 8 months. Synchrony in the Tb rhythm within the group was lost after several months of constant L:D conditions; however, individual rhythms in Tb continued to show clear sine wave-like waxing and waning. AGS displayed spontaneous torpor only during troughs in euthermic Tb. To assess sensitivity to A₁AR activation, AGS were administered the A₁AR agonist N(6)-cyclohexyladenosine (CHA, 0.1 mg/kg, ip), and subcutaneous Tb was monitored. AGS administered CHA during a seasonal minimum in euthermic Tb showed a greater drug-induced decrease in Tb (1.6 ± 0.3 °C) than did AGS administered CHA during a peak in euthermic Tb (0.4 ± 0.3 °C). These results provide evidence for a circannual rhythm in Tb that is associated with increased sensitivity to A₁AR signaling and correlates with the onset of torpor.

  6. Muscle plasticity in hibernating ground squirrels (Spermophilus lateralis) is induced by seasonal, but not low-temperature, mechanisms.

    PubMed

    Nowell, Megan M; Choi, Hyung; Rourke, Bryan C

    2011-01-01

    During hibernation, ground squirrels (Spermophilus lateralis) show unusually altered expression of skeletal muscle myosin heavy-chains. Some muscle groups show transitions from fast to slower myosin isoforms despite atrophy, which are not predicted from other mammalian studies of inactivity. We measure myosin protein and mRNA expression, and the mRNA expression of genes important in atrophy and metabolism in a time-course of muscle plasticity prior to, and during extended hibernation. We also investigate the role of strictly low-temperature processes by comparing torpid individuals at 20 and 4°C. Shifts in myosin isoform expression happen at both temperatures, before the onset of torpor, or within the first month of torpor, in all muscles demonstrating isoform remodeling. Skeletal muscle atrophy is greatly attenuated in this hibernating species, and even may be absent in some muscles. When present, atrophy develops early in hibernation, and does not progress in the final 3 months of torpor. Myostatin mRNA is down-regulated 50-75% in the soleus and diaphragm, two important muscles that are spared of atrophy. The transcription factor FOXO1, which spurs proteolytic degradation of contractile proteins through regulation of the ubiquitin ligase MAFbx, is also generally down-regulated, and may contribute to reduced atrophy. Hypoxia-inducible factor (HIF-1α) mRNA expression was reduced 50% in some muscles, while elevated more than 300% in others. Our collective findings most strongly support early, seasonal, phenotype changes in skeletal muscles which are not uniquely confined to, or prompted by, torpor at 4°C. Such seasonal control of myosin would be a novel mechanism in mammalian skeletal muscle, which otherwise is most susceptible to mechanical loading and limb-activity patterns.

  7. The size of non-hippocampal brain regions varies by season and sex in Richardson's ground squirrel.

    PubMed

    Keeley, R J; Burger, D K; Saucier, D M; Iwaniuk, A N

    2015-03-19

    Sex- and season-specific modulation of hippocampal size and function is observed across multiple species, including rodents. Other non-hippocampal-dependent behaviors exhibit season and sex differences, and whether the associated brain regions exhibit similar variation with sex and season remains to be fully characterized. As such, we examined the brains of wild-caught Richardson's ground squirrels (RGS; Urocitellus richardsonii) for seasonal (breeding, non-breeding) and sex differences in the volumes of specific brain areas, including: total brain volume, corpus callosum (CC), anterior commissure (AC), medial prefrontal cortex (mPFC), total neocortex (NC), entorhinal cortex (EC), and superior colliculus (SC). Analyses of variance and covariance revealed significant interactions between season and sex for almost all areas studied, primarily resulting from females captured during the breeding season exhibiting larger volumes than females captured during the non-breeding season. This was observed for volumes of the AC, mPFC, NC, EC, and SC. Where simple main effects of season were observed for males (the NC and the SC), the volume advantage favoured males captured during the NBr season. Only two simple main effects of sex were observed: males captured in the non-breeding season had significantly larger total brain volume than females captured in the non-breeding season, and females captured during the breeding season had larger volumes of the mPFC and EC than males captured in the breeding season. These results indicate that females have more pronounced seasonal differences in brain and brain region sizes. The extent to which seasonal differences in brain region volumes vary with behaviour is unclear, but our data do suggest that seasonal plasticity is not limited to the hippocampus and that RGS is a useful mammalian species for understanding seasonal plasticity in an ecologically relevant context.

  8. cAMP-dependent protein kinase from brown adipose tissue: temperature effects on kinetic properties and enzyme role in hibernating ground squirrels.

    PubMed

    MacDonald, J A; Storey, K B

    1998-10-01

    Arousal from hibernation requires thermogenesis in brown adipose tissue, a process that is stimulated by beta-adrenergic signals, leading to a rise in intracellular 3',5'-cyclic adenosine monophosphate AMP (cAMP) and activating cAMP-dependent protein kinase A (PKA) to phosphorylate a suite of target proteins and activate lipolysis and uncoupled respiration. To determine whether specific adaptations (perhaps temperature-dependent) facilitate PKA kinetic properties or protein-phosphorylating ability, the catalytic subunit of PKA (PKAc) from interscapular brown adipose of the ground squirrel Spermophilus richardsonii, was purified (final specific activity = 279 nmol phosphate transferred per min per mg protein) and characterized. Physical properties of PKAc included a molecular weight of 41 kDa and an isoelectric point of 7.8 +/- 0.08. A change in assay temperature from a euthermic value (37 degrees C) to one typical of hibernating body temperature (5 degrees C) had numerous significant effects on ground squirrel PKAc including: (a) pH optimum rose from 6.8 at 37 degrees C to 8.7 at 5 degrees C, (b) K(m) values at 37 degrees C for Mg.ATP (49.2 +/- 3.4 microM) and for two phosphate acceptors, Kemptide (50.0 +/- 5.5 microM) and Histone IIA (0.41 +/- 0.05 mg/ml) decreased by 53%, 80% and 51%, respectively, at 5 degrees C, and (c) inhibition by KCl, NaCl and NH4Cl was reduced. However, temperature change had little or no effect on K(m) values of rabbit PKAc, suggesting a specific positive thermal modulation of the hibernator enzyme. Arrhenius plots also differed for the two enzymes; ground squirrel PKAc showed a break in the Arrhenius relationship at 9 degrees C and activation energies that were 29.1 +/- 1.0 kJ/mol for temperatures > 9 degrees C and 2.3-fold higher at 68.1 +/- 2.1 kJ/mol for temperatures < 9 degrees C, whereas the rabbit enzyme showed a breakpoint at 17 degrees C with a 13-fold higher activation energy over the lower temperature range. However

  9. Arctic ground squirrels of the mammoth-steppe: paleoecology of Late Pleistocene middens (˜24 000 29 450 14C yr BP), Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Zazula, Grant D.; Froese, Duane G.; Elias, Scott A.; Kuzmina, Svetlana; Mathewes, Rolf W.

    2007-04-01

    This paper presents paleoecological analyses of 48 fossil arctic ground squirrel ( Spermophilus parryii) middens (nests and caches) recovered from ice-rich loess sediments in the Klondike region of west-central Yukon Territory. AMS radiocarbon dates and stratigraphic association of middens with Dawson tephra (˜25 300 14C yr BP), indicate these paleoecological data reflect the onset of glacial conditions of early Marine Isotope Stage (MIS) 2 and terminal MIS 3 (˜24 000-29 450 14C yr BP). Plant macrofossils include at least 60 plant taxa, including diverse graminoids ( Poa, Elymus trachycaulus, Kobresia myosuroides), steppe forbs ( Penstemon gormanii, Anemone patens var. multifida, Plantago cf. canescens), tundra forbs ( Draba spp., Bistorta vivipara), dwarf shrubs ( Salix cf. arctica, S. cf. polaris), sage ( Artemisia frigida) and rare trees ( Picea mariana). Many of these taxa identified in the middens represent the first recorded fossils for these plants in Eastern Beringia and add to our knowledge of the floristic composition of Pleistocene vegetation and biogeography in this region. Fossil beetles include typical members of the Eastern Beringian steppe-tundra fauna ( Lepidophorus lineaticollis and Connatichela artemisiae) and others suggesting predominantly dry, open habitats. Cache forage selection is suggested by some plant taxa which were particularly frequent and abundant in the middens ( Bistorta vivipara, Kobresia myosuroides, Ranunculus spp., Potentilla, Erysimum cf. cheiranthoides, Poa, Carex and Draba). Factors such as proximity of vegetation to burrows and abundance of fruits and seeds per plant were probably important in cache selection. Glacial conditions enabled arctic ground squirrels to form widespread and dense populations in regions such as the Klondike in which they are rare or absent at present. This fossil midden record supports previous hypotheses that suggest arctic ground squirrels evolved in and are well-adapted to the open, steppe

  10. Functional differentiation of trailing and leading forelimbs during locomotion on the ground and on a horizontal branch in the European red squirrel (Sciurus vulgaris, Rodentia).

    PubMed

    Schmidt, André

    2011-06-01

    Mammalian locomotion is characterized by the frequent use of in-phase gaits in which the footfalls of the left and right fore- or hindlimbs are unevenly spaced in time. Although previous studies have identified a functional differentiation between the first limb (trailing limb) and the second limb (leading limb) to touch the ground during terrestrial locomotion, the influence of a horizontal branch on limb function has never been explored. To determine the functional differences between trailing and leading forelimbs during locomotion on the ground and on a horizontal branch, X-ray motion analysis and force measurements were carried out in two European red squirrels (Sciurus vulgaris, Rodentia). The differences observed between trailing and leading forelimbs were minimal during terrestrial locomotion, where both limbs fulfill two functions and go through a shock-absorbing phase followed by a generating phase. During locomotion on a horizontal branch, European red squirrels reduce speed and all substrate reaction forces transmitted may be due to the reduction of vertical oscillation of the center of mass. Further adjustments during locomotion on a horizontal branch differ significantly between trailing and leading forelimbs and include limb flexion, lead intervals, limb protraction and vertical displacement of the scapular pivot. Consequently, trailing and leading forelimbs perform different functions. Trailing forelimbs function primarily as shock-absorbing elements, whereas leading forelimbs are characterized by a high level of stiffness. This functional differentiation indicates that European red squirrels 'test' the substrate for stability with the trailing forelimb, while the leading forelimb responds to or counteracts swinging or snapping branches.

  11. Immunolocalization of NGF and its Receptors in Ovarian Surface Epithelium of the Wild Ground Squirrel during the Breeding and Nonbreeding Seasons

    PubMed Central

    Bao, L.; Li, Q.; Liu, Y.; Li, B.; Sheng, X.; Han, Y.; Weng, Q.

    2014-01-01

    The ovarian surface epithelium (OSE) plays an important role in normal ovarian physiology. During each reproductive cycle, the OSE takes part in the cyclical ovulatory ruptures and repair. The aim of this study was to investigate the immunolocalization of nerve growth factor (NGF) and its receptors, tyrosine kinase A (TrkA) and p75, in the OSE cells of the wild ground squirrels during the breeding and nonbreeding seasons. There were marked variations in ovarian weight and size between the breeding and the nonbreeding seasons. Histologically, cuboidal cells and squamous cells were identified in the OSE of both seasons. Yet, stronger immunostaining of NGF, TrkA and p75 were observed in cuboidal cells and squamous cells in the breeding season as compared to the nonbreeding season. In addition, plasma gonadotropin concentrations were higher in the breeding season than in the nonbreeding season, suggesting that the expression patterns of NGF, TrkA and p75 in the OSE were correlated with changes in plasma gonadotropins. These findings suggested that NGF and its receptor TrkA and p75 may be involved in the regulation of seasonal changes in the OSE of wild ground squirrel. PMID:24998925

  12. Seasonal changes in expression of nerve growth factor and its receptors TrkA and p75 in the ovary of wild ground squirrel (Citellus dauricus Brandt)

    PubMed Central

    2014-01-01

    The aim of this study was to investigate the presence of nerve growth factor (NGF) and its receptors tyrosine kinase A (TrkA) and p75 in the ovaries of the wild ground squirrels during the breeding and nonbreeding seasons. In the breeding period, NGF, TrkA and p75 were immunolocalized in granulosa cells, thecal cells, interstitial cells and luteal cells whereas in the nonbreeding period, both of them were detected only in granulosa cells, thecal cells and interstitial cells. Stronger immunostaining of NGF, TrkA and p75 were observed in granulosa cells, thecal cells and interstitial cells in the breeding season compared to the nonbreeding season. Corresponding for the immunohistochemical results, immunoreactivities of NGF and its two receptors were greater in the ovaries of the breeding season then decreased to a relatively low level in the nonbreeding season. The mean mRNA levels of NGF, TrkA and p75 were significantly higher in the breeding season than in the nonbreeding season. In addition, plasma gonadotropins, estradiol-17β and progesterone concentrations were significantly higher in the breeding season than in the nonbreeding season, suggesting that the expression patterns of NGF, and TrkA and p75 were correlated with changes in plasma gonadotropins, estradiol-17β and progesterone concentrations. These results indicated that NGF and its receptors, TrkA and p75 may be involved in the regulation of seasonal changes in the ovarian functions of the wild ground squirrel. PMID:24405743

  13. Seasonal changes in expression of nerve growth factor and its receptors TrkA and p75 in the ovary of wild ground squirrel (Citellus dauricus Brandt).

    PubMed

    Li, Ben; Sheng, Xia; Bao, Lihong; Huang, Shiyang; Li, Qinglin; Liu, Yuning; Han, Yingying; Watanabe, Gen; Taya, Kazuyoshi; Weng, Qiang

    2014-01-09

    The aim of this study was to investigate the presence of nerve growth factor (NGF) and its receptors tyrosine kinase A (TrkA) and p75 in the ovaries of the wild ground squirrels during the breeding and nonbreeding seasons. In the breeding period, NGF, TrkA and p75 were immunolocalized in granulosa cells, thecal cells, interstitial cells and luteal cells whereas in the nonbreeding period, both of them were detected only in granulosa cells, thecal cells and interstitial cells. Stronger immunostaining of NGF, TrkA and p75 were observed in granulosa cells, thecal cells and interstitial cells in the breeding season compared to the nonbreeding season. Corresponding for the immunohistochemical results, immunoreactivities of NGF and its two receptors were greater in the ovaries of the breeding season then decreased to a relatively low level in the nonbreeding season. The mean mRNA levels of NGF, TrkA and p75 were significantly higher in the breeding season than in the nonbreeding season. In addition, plasma gonadotropins, estradiol-17β and progesterone concentrations were significantly higher in the breeding season than in the nonbreeding season, suggesting that the expression patterns of NGF, and TrkA and p75 were correlated with changes in plasma gonadotropins, estradiol-17β and progesterone concentrations. These results indicated that NGF and its receptors, TrkA and p75 may be involved in the regulation of seasonal changes in the ovarian functions of the wild ground squirrel.

  14. Testicular expression of NGF, TrkA and p75 during seasonal spermatogenesis of the wild ground squirrel (Citellus dauricus Brandt).

    PubMed

    Zhang, H; Wang, Y; Zhang, J; Wang, L; Li, Q; Sheng, X; Han, Y; Yuan, Z; Weng, Q

    2015-08-10

    The nerve growth factor (NGF) not only has an essential effect on the nervous system, but also plays an important role in a variety of non-neuronal systems, such as the reproductive system. The aim of this study was to investigate the seasonal changes in expression of NGF and its receptors (TrkA and p75) in testes of the wild ground squirrel during the breeding and nonbreeding seasons. Immunolocalization for NGF was detected mainly in Leydig cells and Sertoli cells in testes of the breeding and nonbreeding seasons. The immunoreactivity of TrkA was highest in the elongated spermatids, whereas p75 in spermatogonia and spermatocytes in testes of the breeding season. In the nonbreeding season testes, TrkA showed positive immunostainings in Leydig cells, spermatogonia and primary spermatocytes, while p75 showed positive signals in spermatogonia and primary spermatocytes. Consistent with the immunohistochemical results, the mean mRNA and protein level of NGF and TrkA were higher in the testes of the breeding season, and then decreased to a relatively low level in the nonbreeding season. In addition, the concentration of plasma gonadotropins and testosterone were assayed by radioimmunoassay (RIA), and the results showed a significant seasonal change between the breeding and nonbreeding seasons. To conclude, these results of this study provide the first evidence on the potential involvement of NGF and its receptor, TrkA and p75 in the seasonal spermatogenesis and testicular function change of the wild ground squirrel.

  15. The effects of season and sex on dentate gyrus size and neurogenesis in a wild rodent, Richardson's ground squirrel (Urocitellus richardsonii).

    PubMed

    Burger, D K; Gulbrandsen, T; Saucier, D M; Iwaniuk, A N

    2014-07-11

    Sex and reproductive status affect hippocampal neurogenesis and dentate gyrus (DG) size in rodents. Relatively few studies, however, address these two effects simultaneously and even fewer studies address this issue in wild populations. Here, we examined seasonal and sex differences in neurogenesis and DG size in a wild, polygynous and social rodent, Richardson's ground squirrel (Uriocitellus richardsonii). Based on the behavioral ecology of this species, we predicted that both neurogenesis and DG size would be sexually dimorphic and the degree of dimorphism would be greatest in the breeding season. Using unbiased stereology and doublecortin (DCX) immunohistochemistry, we found that brain volume, DG size and number of DCX cells varied significantly between breeding and non-breeding seasons, but only brain volume and the number of DCX labeled cells differed between the sexes. Both sex and seasonal differences likely reflect circulating hormone levels, but the extent to which these differences relate to space use in this species is unclear. Based on the degree of seasonal differences in neurogenesis and the DG, we suggest that ground squirrels could be considered model species in which to examine hippocampal plasticity in an ecologically valid context.

  16. Hibernating above the permafrost: effects of ambient temperature and season on expression of metabolic genes in liver and brown adipose tissue of arctic ground squirrels.

    PubMed

    Williams, Cory T; Goropashnaya, Anna V; Buck, C Loren; Fedorov, Vadim B; Kohl, Franziska; Lee, Trixie N; Barnes, Brian M

    2011-04-15

    Hibernating arctic ground squirrels (Urocitellus parryii), overwintering in frozen soils, maintain large gradients between ambient temperature (T(a)) and body temperature (T(b)) by substantially increasing metabolic rate during torpor while maintaining a subzero T(b). We used quantitative reverse-transcription PCR (qRT-PCR) to determine how the expression of 56 metabolic genes was affected by season (active in summer vs hibernating), metabolic load during torpor (imposed by differences in T(a): +2 vs -10°C) and hibernation state (torpid vs after arousal). Compared with active ground squirrels sampled in summer, liver from hibernators showed increased expression of genes associated with fatty acid catabolism (CPT1A, FABP1 and ACAT1), ketogenesis (HMGCS2) and gluconeogenesis (PCK1) and decreased expression of genes associated with fatty acid synthesis (ACACB, SCD and ELOVL6), amino acid metabolism, the urea cycle (PAH, BCKDHA and OTC), glycolysis (PDK1 and PFKM) and lipid metabolism (ACAT2). Stage of hibernation (torpid vs aroused) had a much smaller effect, with only one gene associated with glycogen synthesis (GSY1) in liver showing consistent differences in expression levels between temperature treatments. Despite the more than eightfold increase in energetic demand associated with defending T(b) during torpor at a T(a) of -10 vs +2°C, transcript levels in liver and brown adipose tissue differed little. Our results are inconsistent with a hypothesized switch to use of non-lipid fuels when ambient temperatures drop below freezing.

  17. Scaling of the mandible in squirrels.

    PubMed

    Velhagen, W A; Roth, V L

    1997-05-01

    We compared the shape of the mandible among New World tree squirrels and selected outgroup taxa using linear measurements and areas defined by the median axis and conventional anatomical landmarks. We modified the median axis technique to define novel measurements, which proved complementary to those obtained from conventional landmarks. Allometric analyses showed that the scaling of the mandible among the New World tree squirrels is generally isometric (as has been observed in other groups of mammals), but diverges from isometry in a tendency in smaller animals for the masseteric ridge to be displaced anteriorly, the condylar process and posterior portion of the ascending ramus to be relatively elongated, and the coronoid process to be shortened. Allometric analyses also revealed the ways and extent that outgrowth taxa deviated from the scaling pattern observed for the New World tree squirrels. A flying squirrel (subfamily Pteromyinae), a moderate-sized callosciurine squirrel, and three species of pygmy tree squirrels from Asia and Africa show mandibular proportions very similar to those predicted for New World tree squirrels of corresponding size. Ground squirrels (tribe Marmotini) and successively more distant relatives such as Aplodontia, two myomorph rodents, and a rabbit show greater differences from the New World tree squirrels in their mandibular proportions. Combining the use of median-axis and conventional measurements makes it possible to examine changing relationships between locations of anatomically homologous landmarks and the geometry of the form.

  18. Climate-induced changes in autumn impact spring breeding phenology and reproductive fitness in arctic ground squirrels

    NASA Astrophysics Data System (ADS)

    Sheriff, M. J.; Buck, L.; Barnes, B. M.

    2012-12-01

    Rapid climate change and shifts in seasonality can threaten the reproductive success of organisms and have negative consequences for species' range and even persistence. Focus on unidirectional effects of earlier springs and onset of reproduction do not consider effects warming may also have on autumn conditions. Shifts in the timing and duration of autumn conditions may influence spring breeding since earlier autumns may constrain offspring's winter preparation, forcing animals to breed earlier in the spring, while prolonged autumns may extend the time offspring have for winter preparation; this effect may alleviating the necessity of breeding early in spring and ultimately increase reproductive fitness. In the Arctic, warming and change in seasonality is occurring at unprecedented rates that are two to three times that of the global average. Further, rates are accelerating from about 0.15-0.17°C per decade (1961-1990) to about 0.3-0.4°C per decade. Unlike in temperate regions, arctic warming has had and is predicted to continue having major heterogeneous effects on the extent of seasonal snow cover. Future scenarios involve deeper and prolonged spring snow cover due to increased winter precipitation and frequency of spring snowstorms in some areas and reduced snow depth and earlier snowmelt with increased warming, wind, and winter precipitation falling as rain in other areas. Under both scenarios autumn is expected to become later in the year, potentially prolonging the snow free season. Snow cover is extremely important for many arctic animals controlling microclimates, defining the beginning and length of the growing season, affecting plant productivity, and allowing access to food resources. Using long-term data from two nearby populations of free-living arctic ground squirrels (AGS) that includes fine-scale information on timing of hibernation and reproduction, we found that seasonal differences in snow cover significantly influenced AGS breeding phenology

  19. Testicular Expression of NGF, TrkA and p75 During Seasonal Spermatogenesis of the Wild Ground Squirrel (Citellus Dauricus Brandt)

    PubMed Central

    Zhang, H.; Wang, Y.; Zhan, J.; Wang, L.; Li, Q.; Sheng, X.; Han, Y.; Yuan, Z.; Weng, Q.

    2015-01-01

    The nerve growth factor (NGF) not only has an essential effect on the nervous system, but also plays an important role in a variety of non-neuronal systems, such as the reproductive system. The aim of this study was to compare the quality and quantity in expression of NGF and its receptors (TrkA and p75) in testes of the wild ground squirrel during the breeding and nonbreeding seasons. Immunolocalization for NGF was detected mainly in Leydig cells and Sertoli cells in testes of the breeding and nonbreeding seasons. The immunoreactivity of TrkA was highest in the elongated spermatids, whereas p75 in spermatogonia and spermatocytes in testes of the breeding season. In the nonbreeding season testes, TrkA showed positive immunostainings in Leydig cells, spermatogonia and primary spermatocytes, while p75 showed positive signals in spermatogonia and primary spermatocytes. Consistent with the immunohistochemical results, the mean mRNA and protein level of NGF and TrkA were higher in the testes of the breeding season than in non-breeding season, and then decreased to a relatively low level in the nonbreeding season. In addition, the concentration of plasma gonadotropins and testosterone were assayed by radioimmunoassay (RIA), and the results showed a significant difference between the breeding and nonbreeding seasons with higher concentrations in breeding season. In conclusion, these results of this study provide the first evidence on the potential involvement of NGF and its receptor, TrkA and p75 in the seasonal spermatogenesis and testicular function change of the wild ground squirrel. PMID:26428886

  20. Expression of nerve growth factor and its receptors TrkA and p75 in the uterus of wild female ground squirrel (Citellus dauricus Brandt).

    PubMed

    Li, Ben; Sheng, Xia; Song, Moshi; Zhang, Haolin; Weng, Jiaju; Zhang, Mengyuan; Hu, Xiao; Zhou, Jiao; Xu, Meiyu; Weng, Qiang; Watanabe, Gen; Taya, Kazuyoshi

    2012-03-01

    In this study, we investigated the presence of nerve growth factor (NGF) and its receptors tyrosine kinase A (TrkA) and p75 in the uterus of the wild ground squirrels during the estrous period, early pregnancy and non-breeding period. In the estrous period and early pregnancy, NGF and TrkA were immunolocalized in stromal cells, luminal epithelial cells, glandular cells and smooth muscle cells whereas in the non-breeding period, both of them were detected only in luminal epithelial cells and glandular cells, but not in stromal cells or smooth muscle cells. Stronger immunostaining of NGF and TrkA was observed in luminal epithelial cells and glandular cells in the estrous period and early pregnancy as compared to the non-breeding period. p75 was immunolocalized only in luminal epithelial and glandular cells during the estrous period, early pregnancy and non-breeding period. The intensity of the immunohistochemical signals for p75 did not vary significantly in the estrous period, early pregnancy and non-breeding period. The mean mRNA levels of NGF and TrkA and p75 were significantly higher in the estrous period and early pregnancy as compared to the non-breeding period. Besides, plasma estradiol-17β and progesterone concentrations were higher in the estrous period and early pregnancy than in the non-breeding period, suggesting that the expression patterns of NGF and TrkA are correlated with changes in plasma estradiol-17β and progesterone concentrations. These results indicate that NGF and its receptor TrkA may be involved in the regulation of seasonal changes in the uterine functions of wild female ground squirrels.

  1. Skin tumors on squirrels

    USGS Publications Warehouse

    Herman, C.M.; Reilly, J.R.

    1955-01-01

    Skin tumors having the gross appearance of previously reported fibromas are reported on gray squirrels from N. Y., Md., Va., N. C., and W. Va. and from a fox squirrel from W. Va. and a porcupine from Pa.

  2. The effects of hibernation on the contractile and biochemical properties of skeletal muscles in the thirteen-lined ground squirrel, Ictidomys tridecemlineatus.

    PubMed

    James, Rob S; Staples, James F; Brown, Jason C L; Tessier, Shannon N; Storey, Kenneth B

    2013-07-15

    Hibernation is a crucial strategy of winter survival used by many mammals. During hibernation, thirteen-lined ground squirrels, Ictidomys tridecemlineatus, cycle through a series of torpor bouts, each lasting more than a week, during which the animals are largely immobile. Previous hibernation studies have demonstrated that such natural models of skeletal muscle disuse cause limited or no change in either skeletal muscle size or contractile performance. However, work loop analysis of skeletal muscle, which provides a realistic assessment of in vivo power output, has not previously been undertaken in mammals that undergo prolonged torpor during hibernation. In the present study, our aim was to assess the effects of 3 months of hibernation on contractile performance (using the work loop technique) and several biochemical properties that may affect performance. There was no significant difference in soleus muscle power output-cycle frequency curves between winter (torpid) and summer (active) animals. Total antioxidant capacity of gastrocnemius muscle was 156% higher in torpid than in summer animals, suggesting one potential mechanism for maintenance of acute muscle performance. Soleus muscle fatigue resistance was significantly lower in torpid than in summer animals. Gastrocnemius muscle glycogen content was unchanged. However, state 3 and state 4 mitochondrial respiration rates were significantly suppressed, by 59% and 44%, respectively, in mixed hindlimb skeletal muscle from torpid animals compared with summer controls. These findings in hindlimb skeletal muscles suggest that, although maximal contractile power output is maintained in torpor, there is both suppression of ATP production capacity and reduced fatigue resistance.

  3. Three new species of fleas belonging to the genus Macrostylophora from the three-striped ground squirrel, Lariscus insignis, in Java.

    PubMed

    Durden, L A; Beaucournu, J-C

    2014-12-01

    Three new species of fleas belonging to the genus Macrostylophora (Siphonaptera, Ceratophyllidae) are described from the three-striped ground squirrel, Lariscus insignis, from Tjibodas, West Java (Jawa Barat), Indonesia at an elevation of 1500 m. Macrostylophora larisci sp. n. is described from three male specimens, Macrostylophora debilitata sp. n. is described from one male and Macrostylophora wilsoni sp. n. is described from one female. Non-genital morphological characters of the female specimen, including ctenidial spine shapes and lengths, show that it is not the corresponding female for either M. larisci sp. n. or M. debilitata sp. n. It is unusual for three different species of congeneric fleas to parasitize the same host species in the same geographical location. These three new species represent the first known records of Macrostylophora from Java and they could be enzootic vectors between rodents of flea-borne zoonotic pathogens such as Rickettsia typhi and Yersinia pestis, both of which are established on Java. A list is provided of the 43 known species and 12 subspecies of Macrostylophora together with their known geographical distributions and hosts. A map depicting the distributions of known Indonesian (and Bornean) species of Macrostylophora is also included.

  4. Remarkable preservation of Ca2+ homeostasis and inhibition of apoptosis contribute to anti-muscle atrophy effect in hibernating Daurian ground squirrels

    PubMed Central

    Fu, Weiwei; Hu, Huanxin; Dang, Kai; Chang, Hui; Du, Bei; Wu, Xue; Gao, Yunfang

    2016-01-01

    The underlying mechanisms that hibernators deviated from muscle atrophy during prolonged hibernating inactivity remain elusive. This study tested the hypothesis that the maintenance of intracellular Ca2+ homeostasis and inhibition of apoptosis would be responsible for preventing muscle atrophy in hibernating Daurian ground squirrels. The results showed that intracellular Ca2+ homeostasis was maintained in soleus and extensor digitorum longus (EDL) in hibernation and post-hibernation, while cytosolic Ca2+ was overloaded in gastrocnemius (GAS) in hibernation with a recovery in post-hibernation. The Ca2+ overload was also observed in interbout arousals in all three type muscles. Besides, the Bax/Bcl-2 ratio was unchanged in transcriptional level among pre-hibernation, hibernation and interbout arousals, and reduced to a minimum in post-hibernation. Furthermore, the Bax/Bcl-2 ratio in protein level was reduced in hibernation but recovered in interbout arousals. Although cytochrome C was increased in GAS and EDL in post-hibernation, no apoptosis was observed by TUNEL assay. These findings suggested that the intracellular Ca2+ homeostasis in hibernation might be regulated by the cytosolic Ca2+ overload during interbout arousals, which were likely responsible for preventing muscle atrophy via inhibition of apoptosis. Moreover, the muscle-specificity indicated that the different mechanisms against disuse-induced atrophy might be involved in different muscles in hibernation. PMID:27256167

  5. Expression of nuclear factor of activated T cells (NFAT) and downstream muscle-specific proteins in ground squirrel skeletal and heart muscle during hibernation.

    PubMed

    Zhang, Yichi; Storey, Kenneth B

    2016-01-01

    The thirteen-lined ground squirrel (Ictidomys tridecemlineatus) undergoes remarkable adaptive changes during hibernation. Interestingly, skeletal muscle remodelling occurs during the torpor-arousal cycle of hibernation to prevent net muscle loss despite inactivity. Reversible cardiomyocyte hypertrophy occurs in cardiac muscle, allowing the heart to preserve cardiac output during hibernation, while avoiding chronic maladaptive hypertrophy post-hibernation. We propose that calcium signalling proteins [calcineurin (Cn), calmodulin (CaM), and calpain], the nuclear factor of activated T cell (NFAT) family of transcription factors, and the NFAT targets myoferlin and myomaker contribute significantly to adaptations taking place in skeletal and cardiac muscle during hibernation. Protein-level analyses were performed over several conditions: euthermic room temperature (ER), euthermic cold room (EC), entrance into (EN), early (ET), and late torpor (LT) time points, in addition to early (EA), interbout (IA), and late arousal (LA) time points using immunoblotting and DNA-protein interaction (DPI) enzyme-linked immunosorbent assay (ELISAs). In skeletal and cardiac muscle, NFATc2 protein levels were elevated during torpor. NFATc4 increased throughout the torpor-arousal cycle in both tissues, and NFATc1 showed this trend in cardiac muscle only. NFATc3 showed an elevation in DNA-binding activity but not expression during torpor. Myoferlin protein levels dramatically increased during torpor in both skeletal and cardiac muscle. Myomaker levels also increased significantly in cardiac muscle during torpor. Cardiac Cn levels remained stable, whereas CaM and calpain decreased throughout the torpor-arousal cycle. Activation and/or upregulation of NFATc2, c3, myoferlin, and myomaker at torpor could be part of a stress-response mechanism to preserve skeletal muscle mass, whereas CaM and calpain appear to initiate the rapid reversal of cardiac hypertrophy during arousal through

  6. Coping with pregnancy after 9months in the dark: Post-hibernation buffering of high maternal stress in arctic ground squirrels.

    PubMed

    Edwards, Phoebe D; Boonstra, Rudy

    2016-06-01

    Pregnancy and lactation are key times in the life of female mammals when energetic resources must be brought to bear to produce and nurture offspring. Changes in glucocorticoid (GC) levels are central to this objective, due to their roles in modulating development and physiology and in mediating energetic tradeoffs. We examined GC changes over reproduction in a species living in a harsh seasonal environment: the arctic ground squirrel (Urocitellus parryii). Females become pregnant immediately after emerging from a ∼9month hibernation, and then must begin this pregnancy during an additional month of freezing temperatures and limited food availability. We measured plasma levels of total cortisol, corticosteroid-binding globulin (CBG), and free cortisol in unstressed females at three stages: not-visibly pregnant, visibly pregnant, and lactating. Total cortisol levels were similar in all stages, but CBG levels increased 4-fold from the not-visibly pregnant stage to visibly pregnant and lactating stage. As a result, the free cortisol fraction declined from 51% of total cortisol when females were not-visibly pregnant to only 5% when they were visibly pregnant (remaining low and stable throughout pregnancy) and 10% when they were lactating. This pattern is markedly different from that seen in other mammals, where 10% or less of GCs are free and these tend to increase during gestation. We postulate that the high free cortisol just prior to visible pregnancy is a seasonal adaptation relating either to the pronounced physiological changes the female must undergo after emerging from hibernation and immediately getting pregnant, or to the mobilization of body reserves for energy to permit pregnancy, or both. Thereafter, high CBG levels may shield the developing offspring from the negative effects of cortisol overexposure.

  7. Characterization of the SIRT family of NAD+-dependent protein deacetylases in the context of a mammalian model of hibernation, the thirteen-lined ground squirrel.

    PubMed

    Rouble, Andrew N; Storey, Kenneth B

    2015-10-01

    Hibernating mammals employ strong metabolic rate depression to survive the winter, thereby avoiding the high energy costs of maintaining a euthermic lifestyle in the face of low seasonal temperatures and limited food resources. Characteristics of this natural torpor include a significant reduction in body temperature, a shift to a lipid-based metabolism, global suppression of ATP-expensive activities, and the upregulation of selected genes that mediate biochemical reorganization and cytoprotection. Sirtuin (SIRT) proteins, an evolutionarily conserved family of NAD(+)-dependent protein deacetylases, have been shown to play important roles in the post-translational regulation of many metabolic and cytoprotective processes, suggesting a potential function for these enzymes in the control of hibernation. To assess this possibility, protein levels of the seven mammalian SIRTs (SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7), total SIRT activity, and the acetylation status of two downstream SIRT targets (SOD2K68 and NF-κB p65K310) were measured in skeletal muscle, liver, brown adipose and white adipose tissues of the hibernating thirteen-lined ground squirrel (Ictidomys tridecemlineatus) over the course of the torpor-arousal cycle. The analysis revealed tissue-specific responses of different SIRTs at various points throughout hibernation, including a potentially interesting correlation between increased levels of SIRT3 protein, heightened total SIRT activity, and decreased acetylation of SIRT3 downstream target SOD2K68 in skeletal muscle during late torpor. These results provide evidence to suggest a possible role for the SIRT family of protein deacetylases in the regulation of the metabolic and cellular protective pathways that mediate the process of mammalian hibernation.

  8. Dynamic changes in global and gene-specific DNA methylation during hibernation in adult thirteen-lined ground squirrels, Ictidomys tridecemlineatus.

    PubMed

    Alvarado, Sebastian; Mak, Timothy; Liu, Sara; Storey, Kenneth B; Szyf, Moshe

    2015-06-01

    Hibernating mammals conserve energy in the winter by undergoing prolonged bouts of torpor, interspersed with brief arousals back to euthermia. These bouts are accompanied by a suite of reversible physiological and biochemical changes; however, much remains to be discovered about the molecular mechanisms involved. Given the seasonal nature of hibernation, it stands to reason that underlying plastic epigenetic mechanisms should exist. One such form of epigenomic regulation involves the reversible modification of cytosine bases in DNA by methylation. DNA methylation is well known to be a mechanism that confers upon DNA its cellular identity during differentiation in response to innate developmental cues. However, it has recently been hypothesized that DNA methylation also acts as a mechanism for adapting genome function to changing external environmental and experiential signals over different time scales, including during adulthood. Here, we tested the hypothesis that DNA methylation is altered during hibernation in adult wild animals. This study evaluated global changes in DNA methylation in response to hibernation in the liver and skeletal muscle of thirteen-lined ground squirrels along with changes in expression of DNA methyltransferases (DNMT1/3B) and methyl binding domain proteins (MBDs). A reduction in global DNA methylation occurred in muscle during torpor phases whereas significant changes in DNMTs and MBDs were seen in both tissues. We also report dynamic changes in DNA methylation in the promoter of the myocyte enhancer factor 2C (mef2c) gene, a candidate regulator of metabolism in skeletal muscle. Taken together, these data show that genomic DNA methylation is dynamic across torpor-arousal bouts during winter hibernation, consistent with a role for this regulatory mechanism in contributing to the hibernation phenotype.

  9. Seasonal expression of androgen receptor, aromatase, and estrogen receptor alpha and beta in the testis of the wild ground squirrel (Citellus dauricus Brandt).

    PubMed

    Li, Q; Zhang, F; Zhang, S; Sheng, X; Han, X; Weng, Q; Yuan, Z

    2015-02-17

    The aim of this study was to investigate the seasonal expression of androgen receptor (AR), estrogen receptors α and β (ERα and ERβ) and aromatase cytochrome P450 (P450arom) mRNA and protein by real-time PCR and immunohistochemistry in the wild ground squirrel (WGS) testes. Histologically, all types of spermatogenic cells including mature spermatozoa were identified in the breeding season (April), while spermatogonia and primary spermatocytes were observed in the nonbreeding season (June), and spermatogonia, primary spermatocytes and secondary spermatocytes were found in pre-hibernation (September). AR was present in Leydig cells, peritubular myoid cells and Sertoli cells in the breeding season and pre-hibernation with more intense staining in the breeding season, whereas AR was only found in Leydig cells in the nonbreeding season; P450arom was expressed in Leydig cells, Sertoli cells and germ cells during the breeding season, whereas P450arom was found in Leydig cells and Sertoli cells during pre-hibernation, but P450arom was not present in the nonbreeding season; stronger immunohistochemical signal for ERα was present in Sertoli cells and Leydig cells during the breeding season; ERβ was only expressed in Leydig cells of the breeding season. Consistent with the immunohistochemical results, the mean mRNA level of AR, P450arom, ERα and ERβ were higher in the testes of the breeding season when compared to pre-hibernation and the nonbreeding season. These results suggested that the seasonal changes in spermatogenesis and testicular recrudescence and regression process in WGSs might be correlated with expression levels of AR, P450arom and ERs, and that estrogen and androgen may play an important autocrine/paracrine role to regulate seasonal testicular function.

  10. Phylogeny, biogeography and systematic revision of plain long-nosed squirrels (genus Dremomys, Nannosciurinae).

    PubMed

    Hawkins, Melissa T R; Helgen, Kristofer M; Maldonado, Jesus E; Rockwood, Larry L; Tsuchiya, Mirian T N; Leonard, Jennifer A

    2016-01-01

    The plain long-nosed squirrels, genus Dremomys, are high elevation species in East and Southeast Asia. Here we present a complete molecular phylogeny for the genus based on nuclear and mitochondrial DNA sequences. Concatenated mitochondrial and nuclear gene trees were constructed to determine the tree topology, and date the tree. All speciation events within the plain-long nosed squirrels (genus Dremomys) were ancient (dated to the Pliocene or Miocene), and averaged older than many speciation events in the related Sunda squirrels, genus Sundasciurus. Within the plain long-nosed squirrels, the most recent interspecific split occurred 2.9 million years ago, older than some splits within Sunda squirrels, which dated to the Pleistocene. Our results demonstrate that the plain long-nosed squirrels are not monophyletic. The single species with a distinct distribution, the Bornean mountain ground squirrel (Dremomys everetti), which is endemic to the high mountains of Borneo, is nested within the Sunda squirrels with high support. This species diverged from its sister taxa in the Sunda squirrels 6.62 million years ago, and other plain long-nosed squirrels over 11 million years ago. Our analyses of morphological traits in these related genera support the re-classification of the Bornean mountain ground squirrel, Dremomys everetti, to the genus Sundasciurus, which changes its name to Sundasciurus everetti. Past inclusion in the plain long-nosed squirrels (Dremomys) reflects convergent evolution between these high elevation species.

  11. Variegated Squirrel Bornavirus 1 in Squirrels, Germany and the Netherlands

    PubMed Central

    Schlottau, Kore; Jenckel, Maria; van den Brand, Judith; Fast, Christine; Herden, Christiane; Höper, Dirk; Homeier-Bachmann, Timo; Thielebein, Jens; Mensing, Niels; Diender, Bert; Hoffmann, Donata; Ulrich, Rainer G.; Mettenleiter, Thomas C.; Koopmans, Marion; Tappe, Dennis; Schmidt-Chanasit, Jonas; Reusken, Chantal B.E.M.; Hoffmann, Bernd

    2017-01-01

    We screened squirrels in Germany and the Netherlands for the novel zoonotic variegated squirrel bornavirus 1 (VSBV-1). The detection of VSBV-1 in 11 squirrels indicates a considerable risk for transmission to humans handling those animals. Therefore, squirrels in contact with humans should routinely be tested for VSBV-1. PMID:28221112

  12. The influence of 1-10 kD fraction from brains of the hibernating ground squirrel and the Yakut horse on proliferation and protein synthesizing system of Ehrlich ascitic carcinoma cells.

    PubMed

    Gulevsky, A K; Grischenko, V I; Tereschenko, O S; Shchenyavcky, I J

    2005-01-01

    The experimental data presented in the work testify to the cytostatic activity of 1-10 kD polypeptide fractions from brains of the hibernating ground squirrel and the Yakut horse towards Ehrlich ascitic carcinoma (EAC) cells. The experiments on the investigation of the inhibiting influence of 1-10 kD fractions from tissues of the hibernating and cold-adapted animals on protein-synthesizing system of EAC cells allow us to conclude that the cytostatic effect of the fractions is effected at the genetic level in the tumor cells.

  13. A squirrel searches for food at KSC

    NASA Technical Reports Server (NTRS)

    1999-01-01

    An Eastern gray squirrel pauses in its daily search for food in the Merritt Island National Wildlife Refuge, which shares a boundary with Kennedy Space Center. The Eastern gray squirrel is found in wooded, suburban, and urban areas statewide. It nests in tree hollows or leaf nests in treetops. It forages during the day, mainly early morning and late afternoon, both on the ground and in trees, living on a diet of acorns, nuts, fruits, berries, insects, and bird eggs. Food plants include cypress, buckeyes, elms, grapes, tulip trees, mulberries, and tupelo. It breeds in late winter or early spring and again in late spring or summer, bearing two to six young. The eastern gray squirrel chatters when disturbed. The 92,000-acre wildlife refuge is a habitat for more than 310 species of birds, 25 mammals, 117 fishes and 65 amphibians and reptiles.

  14. Seasonal changes in spermatogenesis and immunolocalization of cytochrome P450 17alpha-hydroxylase/c17-20 lyase and cytochrome P450 aromatase in the wild male ground squirrel (Citellus dauricus Brandt).

    PubMed

    Zhang, Haolin; Sheng, Xia; Hu, Xiao; Li, Xiuwen; Xu, Hui; Zhang, Mengyuan; Li, Ben; Xu, Meiyu; Weng, Qiang; Zhang, Zhixiang; Taya, Kazuyoshi

    2010-06-01

    The purpose of this study was to investigate seasonal changes of spermatogenesis and the cellular localization of P450c17 and P450arom in wild male ground squirrels during the breeding and non-breeding seasons. The testicular weight, testicular size and score count of spermatogenesis from April to September were measured, and histological and immunohistochemical observations of testicular tissues were performed in wild male ground squirrels. In addition, total proteins were extracted from testicular tissue in the breeding and non-breeding seasons and were used for Western blotting analysis for P450c17 and P450arom. There were marked variations in testicular weight, testicular size and score count of spermatogenesis from the breeding season (April) to the non-breeding season (September). Histologically, spermatogonia, primary spermatocytes, secondary spermatocytes and spermatozoa were identified in the breeding season (April). Immunolocalization of P450c17 was detected in Leydig cells and spermatozoa during the breeding season and was only found in Leydig cells during the non-breeding season. The positive signals of P450c17 by Western blotting were both observed in the breeding and non-breeding seasons. Immunolocalization of P450arom was observed in Leydig cells, Sertoli cells and all types of spermatogenic cells including mature-phase spermatozoa in the breeding season, while immunoreactivity for P450arom was not present in the testis of the non-breeding season. With P450arom antibody, a band was also only detected in the breeding season by Western blotting. These results suggest that the seasonal changes in testicular weight and size are correlated with spermatogenesis and immunolocalization of P450c17 and P450arom, and androgen and estrogen may play an important role in the spermatogenesis and testicular recrudescence and regression process.

  15. Squirrel Foraging Preferences: Gone Nuts?

    ERIC Educational Resources Information Center

    Darling, Randi A.

    2007-01-01

    This field exercise examines the feeding preferences of Gray Squirrels ("Sciurus carolinensis"). Students present squirrels with a variety of food types in a cafeteria-style arrangement in order to test hypotheses about foraging preferences. This exercise, which is appropriate for introductory biology, ecology, and animal behavior classes, is…

  16. Geohydrology, water quality, and preliminary simulations of ground-water flow of the alluvial aquifer in the Upper Black Squirrel Creek basin, El Paso County, Colorado

    USGS Publications Warehouse

    Buckles, D.R.; Watts, K.R.

    1988-01-01

    The upper Black Squirrel Creek basin in eastern El Paso County, Colorado, is underlain by an alluvial aquifer and four bedrock aquifers. Groundwater pumpage from the alluvial aquifer has increased since the mid-1950's, and water level declines have been substantial; the bedrock aquifers virtually are undeveloped. Groundwater pumpage for domestic, stock, agricultural, and municipal uses have exceeded recharge for the past 25 years. The present extent of the effect of pumpage on the alluvial aquifer was evaluated, and a groundwater flow model was used to simulate the future effect of continued pumpage on the aquifer. Measured water level declines from 1974 through 1984 were as much as 30 ft in an area north of Ellicott, Colorado. On the basis of the simulations, water level declines from October 1984 to April 1999 north of Ellicott might be as much as 20 to 30 ft and as much as 1 to 10 ft in most of the aquifer. The groundwater flow models provided a means of evaluating the importance of groundwater evapotranspiration at various stages of aquifer development. Simulated groundwater evapotranspiration was about 43% of the outflow from the aquifer during predevelopment stages but was less than 3% of the outflow from the aquifer during late-development stages. Analyses of 36 groundwater samples collected during 1984 indicated that concentrations of dissolved nitrite plus nitrate as nitrogen generally were large. Samples from 5 of the 36 wells had concentrations of dissolved nitrite plus nitrate as nitrogen that exceeded drinking water standards. Water from the alluvial aquifer generally is of suitable quality for most uses. (USGS)

  17. Simultaneous measurement of brain tissue oxygen partial pressure, temperature, and global oxygen consumption during hibernation, arousal, and euthermy in non-sedated and non-anesthetized Arctic ground squirrels.

    PubMed

    Ma, Yilong; Wu, Shufen

    2008-09-30

    This study reports an online temperature correction method for determining tissue oxygen partial pressure P(tO2) in the striatum and a novel simultaneous measurement of brain P(tO2) and temperature (T(brain)) in conjunction with global oxygen consumption V(O2) in non-sedated and non-anesthetized freely moving Arctic ground squirrels (AGS, Spermophilus parryii). This method fills an important research gap-the lack of a suitable method for physiologic studies of tissue P(O2) in hibernating or other cool-blooded species. P(tO2) in AGS brain during euthermy (21.22+/-2.06 mmHg) is significantly higher (P=0.016) than during hibernation (13.21+/-0.46 mmHg) suggests brain oxygenation in the striatum is normoxic during euthermy and hypoxic during hibernation. These results in P(tO2) are different from blood oxygen partial pressure P(aO2) in AGS, which are significantly lower during euthermy than during hibernation and are actually hypoxic during euthermy and normoxic during hibernation in our previous study. This intriguing difference between the P(O2) of brain tissue and blood during these two physiological states suggests that regional mechanisms in the brain play a role in maintaining tissue oxygenation and protect against hypoxia during hibernation.

  18. Squirrels--A Teaching Resource in Your Schoolyard.

    ERIC Educational Resources Information Center

    LaHart, David E.

    1991-01-01

    This lesson plan demonstrates how to use common animals in your backyard or school grounds to study basic ecological principles with students. An example study uses squirrels for observational study. Includes background information, references, suggested equipment, activities, and observation techniques. (MCO)

  19. Stable atrogin-1 (Fbxo32) and MuRF1 (Trim63) gene expression is involved in the protective mechanism in soleus muscle of hibernating Daurian ground squirrels (Spermophilus dauricus)

    PubMed Central

    Dang, Kai; Li, Ya-Zhao; Gong, Ling-Chen; Xue, Wei; Wang, Hui-Ping; Goswami, Nandu; Gao, Yun-Fang

    2016-01-01

    ABSTRACT Understanding the mechanisms that protect against or limit muscle atrophy in hibernators during prolonged inactivity has important implications for its treatment. We examined whether external factors influence the pathways regulating protein synthesis and degradation, leading to muscle atrophy prevention in Daurian ground squirrels (Spermophilus dauricus). We investigated the effects of 14-day hindlimb-unloading (HU) in different seasons and two-month hibernation on the soleus (SOL) muscle wet mass, muscle-to-body mass ratio, fiber cross sectional area (CSA), fiber distribution and muscle ultrastructure. We also measured changes in the protein expression and activation states of Akt, mTOR and FoxO1 and the mRNA expression of atrogin-1 and MuRF1. Compared with the control groups, autumn and winter HU significantly lowered SOL muscle wet mass and muscle-to-body mass ratio, decreased type I and II fiber CSA and induced ultrastructural anomalies. However, these measured indices were unchanged between Pre-hibernation and Hibernation groups. Furthermore, phosphorylation levels of Akt and mTOR significantly decreased, while the phosphorylation level of FoxO1 and mRNA expression of atrogin-1 and MuRF1 increased after HU. During hibernation, the phosphorylation levels of Akt and mTOR significantly decreased, but the phosphorylation level of FoxO1 and mRNA expression of atrogin-1 and MuRF1 remained unchanged. Overall, our findings suggest that disuse and seasonality may not be sufficient to initiate the innate protective mechanism that prevents SOL atrophy during prolonged periods of hibernation inactivity. The stable expression of atrogin-1 and MuRF1 may facilitate to prevent SOL atrophy via controlling ubiquitination of muscle proteins during hibernation. PMID:26740574

  20. Stable atrogin-1 (Fbxo32) and MuRF1 (Trim63) gene expression is involved in the protective mechanism in soleus muscle of hibernating Daurian ground squirrels (Spermophilus dauricus).

    PubMed

    Dang, Kai; Li, Ya-Zhao; Gong, Ling-Chen; Xue, Wei; Wang, Hui-Ping; Goswami, Nandu; Gao, Yun-Fang

    2016-01-06

    Understanding the mechanisms that protect against or limit muscle atrophy in hibernators during prolonged inactivity has important implications for its treatment. We examined whether external factors influence the pathways regulating protein synthesis and degradation, leading to muscle atrophy prevention in Daurian ground squirrels (Spermophilus dauricus). We investigated the effects of 14-day hindlimb-unloading (HU) in different seasons and two-month hibernation on the soleus (SOL) muscle wet mass, muscle-to-body mass ratio, fiber cross sectional area (CSA), fiber distribution and muscle ultrastructure. We also measured changes in the protein expression and activation states of Akt, mTOR and FoxO1 and the mRNA expression of atrogin-1 and MuRF1. Compared with the control groups, autumn and winter HU significantly lowered SOL muscle wet mass and muscle-to-body mass ratio, decreased type I and II fiber CSA and induced ultrastructural anomalies. However, these measured indices were unchanged between Pre-hibernation and Hibernation groups. Furthermore, phosphorylation levels of Akt and mTOR significantly decreased, while the phosphorylation level of FoxO1 and mRNA expression of atrogin-1 and MuRF1 increased after HU. During hibernation, the phosphorylation levels of Akt and mTOR significantly decreased, but the phosphorylation level of FoxO1 and mRNA expression of atrogin-1 and MuRF1 remained unchanged. Overall, our findings suggest that disuse and seasonality may not be sufficient to initiate the innate protective mechanism that prevents SOL atrophy during prolonged periods of hibernation inactivity. The stable expression of atrogin-1 and MuRF1 may facilitate to prevent SOL atrophy via controlling ubiquitination of muscle proteins during hibernation.

  1. European red squirrel population dynamics driven by squirrelpox at a gray squirrel invasion interface.

    PubMed

    Chantrey, Julian; Dale, Timothy D; Read, Jonathan M; White, Steve; Whitfield, Fiona; Jones, David; McInnes, Colin J; Begon, Michael

    2014-10-01

    Infectious disease introduced by non-native species is increasingly cited as a facilitator of native population declines, but direct evidence may be lacking due to inadequate population and disease prevalence data surrounding an outbreak. Previous indirect evidence and theoretical models support squirrelpox virus (SQPV) as being potentially involved in the decline of red squirrels (Sciurus vulgaris) following the introduction of the non-native gray squirrel (Sciurus carolinensis) to the United Kingdom. The red squirrel is a major UK conservation concern and understanding its continuing decline is important for any attempt to mitigate the decline. The red squirrel-gray squirrel system is also exemplary of the interplay between infectious disease (apparent competition) and direct competition in driving the replacement of a native by an invasive species. Time series data from Merseyside are presented on squirrel abundance and squirrelpox disease (SQPx) incidence, to determine the effect of the pathogen and the non-native species on the native red squirrel populations. Analysis indicates that SQPx in red squirrels has a significant negative impact on squirrel densities and their population growth rate (PGR). There is little evidence for a direct gray squirrel impact; only gray squirrel presence (but not density) proved to influence red squirrel density, but not red squirrel PGR. The dynamics of red SQPx cases are largely determined by previous red SQPx cases, although previous infection of local gray squirrels also feature, and thus, SQPV-infected gray squirrels are identified as potentially initiating outbreaks of SQPx in red squirrels. Retrospective serology indicates that approximately 8% of red squirrels exposed to SQPV may survive infection during an epidemic. This study further highlights the UK red squirrel - gray squirrel system as a classic example of a native species population decline strongly facilitated by infectious disease introduced by a non

  2. Daily Activity and Nest Occupation Patterns of Fox Squirrels (Sciurus niger) throughout the Year

    PubMed Central

    Wassmer, Thomas; Refinetti, Roberto

    2016-01-01

    The authors investigated the general activity and nest occupation patterns of fox squirrels in a natural setting using temperature-sensitive data loggers that measure activity as changes in the microenvironment of the animal. Data were obtained from 25 distinct preparations, upon 14 unique squirrels, totaling 1385 recording days. The animals were clearly diurnal, with a predominantly unimodal activity pattern, although individual squirrels occasionally exhibited bimodal patterns, particularly in the spring and summer. Even during the short days of winter (9 hours of light), the squirrels typically left the nest after dawn and returned before dusk, spending only about 7 hours out of the nest each day. Although the duration of the daily active phase did not change with the seasons, the squirrels exited the nest earlier in the day when the days became longer in the summer and exited the nest later in the day when the days became shorter in the winter, thus tracking dawn along the seasons. During the few hours spent outside the nest each day, fox squirrels seemed to spend most of the time sitting or lying. These findings suggest that fox squirrels may have adopted a slow life history strategy that involves long periods of rest on trees and short periods of ground activity each day. PMID:26963918

  3. European red squirrel population dynamics driven by squirrelpox at a gray squirrel invasion interface

    PubMed Central

    Chantrey, Julian; Dale, Timothy D; Read, Jonathan M; White, Steve; Whitfield, Fiona; Jones, David; McInnes, Colin J; Begon, Michael

    2014-01-01

    Infectious disease introduced by non-native species is increasingly cited as a facilitator of native population declines, but direct evidence may be lacking due to inadequate population and disease prevalence data surrounding an outbreak. Previous indirect evidence and theoretical models support squirrelpox virus (SQPV) as being potentially involved in the decline of red squirrels (Sciurus vulgaris) following the introduction of the non-native gray squirrel (Sciurus carolinensis) to the United Kingdom. The red squirrel is a major UK conservation concern and understanding its continuing decline is important for any attempt to mitigate the decline. The red squirrel–gray squirrel system is also exemplary of the interplay between infectious disease (apparent competition) and direct competition in driving the replacement of a native by an invasive species. Time series data from Merseyside are presented on squirrel abundance and squirrelpox disease (SQPx) incidence, to determine the effect of the pathogen and the non-native species on the native red squirrel populations. Analysis indicates that SQPx in red squirrels has a significant negative impact on squirrel densities and their population growth rate (PGR). There is little evidence for a direct gray squirrel impact; only gray squirrel presence (but not density) proved to influence red squirrel density, but not red squirrel PGR. The dynamics of red SQPx cases are largely determined by previous red SQPx cases, although previous infection of local gray squirrels also feature, and thus, SQPV-infected gray squirrels are identified as potentially initiating outbreaks of SQPx in red squirrels. Retrospective serology indicates that approximately 8% of red squirrels exposed to SQPV may survive infection during an epidemic. This study further highlights the UK red squirrel – gray squirrel system as a classic example of a native species population decline strongly facilitated by infectious disease introduced by a non

  4. Ultrasonic Vocalizations Emitted by Flying Squirrels

    PubMed Central

    Murrant, Meghan N.; Bowman, Jeff; Garroway, Colin J.; Prinzen, Brian; Mayberry, Heather; Faure, Paul A.

    2013-01-01

    Anecdotal reports of ultrasound use by flying squirrels have existed for decades, yet there has been little detailed analysis of their vocalizations. Here we demonstrate that two species of flying squirrel emit ultrasonic vocalizations. We recorded vocalizations from northern (Glaucomys sabrinus) and southern (G. volans) flying squirrels calling in both the laboratory and at a field site in central Ontario, Canada. We demonstrate that flying squirrels produce ultrasonic emissions through recorded bursts of broadband noise and time-frequency structured frequency modulated (FM) vocalizations, some of which were purely ultrasonic. Squirrels emitted three types of ultrasonic calls in laboratory recordings and one type in the field. The variety of signals that were recorded suggest that flying squirrels may use ultrasonic vocalizations to transfer information. Thus, vocalizations may be an important, although still poorly understood, aspect of flying squirrel social biology. PMID:24009728

  5. The Autopsy of Squirrel Doe

    ERIC Educational Resources Information Center

    Dick, Timothy T.; Watson, Jason

    2005-01-01

    Introductory biology laboratory experiences frequently rely on preserved chordates for anatomical study. Unfortunately, these preserved organisms rarely reflect the appearance of a living creature. Since community colleges are generally prohibited the use of live chordates, this paper describes the autopsy of a "road kill" squirrel to facilitate…

  6. Jaw muscles of Old World squirrels.

    PubMed

    Thorington, R W; Darrow, K

    1996-11-01

    The jaw, suprahyoid, and extrinsic tongue muscles were studied in 11 genera, belonging to five tribes, of Old World squirrels. Significant variation in most of the adductor muscles is evident. The most primitive state of sciuromorphy is seen in the African tree squirrels Paraxerus and Funisciurus, especially as reflected in the anterior deep masseter. A derived state of sciuromorphy is found in five genera of Old World squirrels and perhaps evolved independently in each. Reduction of the temporalis muscle was observed in three genera, distantly related to one another. A unique arrangement of the superficial masseter is reported in the Asian giant tree squirrels, Ratufa. The arrangement of the masseter in the African pygmy squirrel, Myosciurus, is very similar to that of the South American pygmy squirrel, Sciurillus. We present hypotheses about the functional significance of these differences. In the derived state of sciuromorphy, which is found in three cases in squirrels that feed extensively on hard fruits, the anterior deep masseter is well positioned to increase the strength of the power stroke of the incisor bite. Among the pygmy squirrels, the position of the anterior deep masseter suggests that it plays a more significant role in molar chewing.

  7. Atypical Histiocytosis in Red Squirrels (Sciurus vulgaris).

    PubMed

    Smith, S H; Stevenson, K; Del-Pozo, J; Moss, S; Meredith, A

    2017-03-17

    Four red squirrels (Sciurus vulgaris) were subjected to necropsy examination over a 3-year period as part of a broader surveillance study. The squirrels presented with cutaneous, subcutaneous and/or internal swellings and nodules that consisted microscopically of sheets of atypical round cells and multinucleated giant cells. There was moderate anisokaryosis with rare mitoses. Nuclei ranged from oval to indented or C-shaped and some were bizarre, twisted or multilobulated. Many giant cells also had a bizarre morphology, with anisokaryosis within individual cells. Giant cell nuclei were often multilobulated, ring-shaped or segmented. Affected internal organs varied depending on the squirrel, but included lymph node, kidney, intestinal tract and lungs. Representative lesions from each of the four squirrels were negative for acid-fast organisms. Formalin-fixed tissues from all four squirrels and ethanol-fixed tissue from one animal were negative for Mycobacterium by polymerase chain reaction. Immunohistochemically, the majority of mononuclear and multinucleated giant cells in all four squirrels strongly expressed vimentin and class II molecules of the major histocompatibility complex. Otherwise, the atypical mononuclear and multinucleated cells were negative for CD3, Pax-5, Mac387, CD18 and E-cadherin. Based on the combination of cellular morphology, arrangement and immunophenotype, a novel form of atypical histiocytosis is considered most likely in these squirrels, although the exact origin and triggering factors remain uncertain.

  8. Endemic Viruses of Squirrel Monkeys (Saimiri spp.)

    PubMed Central

    Rogers, Donna L; McClure, Gloria B; Ruiz, Julio C; Abee, Christian R; Vanchiere, John A

    2015-01-01

    Nonhuman primates are the experimental animals of choice for the study of many human diseases. As such, it is important to understand that endemic viruses of primates can potentially affect the design, methods, and results of biomedical studies designed to model human disease. Here we review the viruses known to be endemic in squirrel monkeys (Saimiri spp.). The pathogenic potential of these viruses in squirrel monkeys that undergo experimental manipulation remains largely unexplored but may have implications regarding the use of squirrel monkeys in biomedical research. PMID:26141448

  9. Tularemia without lesions in grey tree squirrels: A diagnostic challenge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fifteen cases of Francisella tularenesis infection (tularemia) were identified in western grey (Sciurus griseus) and eastern grey (Sciurus carolinesis) squirrels submitted to the Washington Animal Disease Diagnostic Laboratory between 2008 and 2011. All of the squirrels originated in Washington stat...

  10. The occurrence of hepatozoon in the gray squirrel (Sciurus carolinensis)

    USGS Publications Warehouse

    Herman, C.M.; Price, D.L.

    1955-01-01

    Hepatozoon sciuri (Coles, 1914) is reported from gray squirrels (Sciurus carolinensis) in Washington, D.C. and Maryland. Blood smears stained with Giemsa's stain revealed a parasitemia in 16 to 71% of the squirrels examined. A technique for laking the red cells and concentrating the white cells in blood samples demonstrated this protozoon to be present in every squirrel so tested.

  11. Color Vision Sensitivity in Normally Dichromatic Species and Humans

    DTIC Science & Technology

    2007-11-02

    postre - ceptoral color processing. To test this, we determined color discrimination thresholds in normally occurring dichromats, including the chipmunk, the 13-lined ground squirrel, and the tree shrew.

  12. Jaw muscles of New World squirrels.

    PubMed

    Ball, S S; Roth, V L

    1995-06-01

    The jaw, suprahyoid, and extrinsic tongue muscles are described for eight species of New World squirrels, spanning more than an order of magnitude in body mass. Anatomical differences are discussed in the light of body size, natural history, and phylogeny. The relative sizes of different muscles, their orientations, and the shapes and positions of their areas of attachment vary but show few trends in relation to body size. The anatomical differences are likewise not readily explained by the mechanical requirements of the animals' diets, which are similar. The most marked anatomical differences occur in Sciurillus (the pygmy tree squirrel), as well as those genera--Glaucomys (the flying squirrel) and Tamias (the chipmunk)--that are taxonomically most distinct from the tree squirrels. Sciurillus is noteworthy for its unusually small temporalis and an anterior deep masseter that is oriented to assist in retraction of the jaw. Tamias has a more vertically oriented temporalis and greater inclination in the anterior masseter muscles than the other squirrels, features that may be associated with its large diastema and relatively posteriorly situated cheek teeth, which in turn may relate to its having cheek pouches. Our results form a valuable database of information to be used in further studies of functional morphology and phylogeny.

  13. Coevolution of venom function and venom resistance in a rattlesnake predator and its squirrel prey.

    PubMed

    Holding, Matthew L; Biardi, James E; Gibbs, H Lisle

    2016-04-27

    Measuring local adaptation can provide insights into how coevolution occurs between predators and prey. Specifically, theory predicts that local adaptation in functionally matched traits of predators and prey will not be detected when coevolution is governed by escalating arms races, whereas it will be present when coevolution occurs through an alternate mechanism of phenotype matching. Here, we analyse local adaptation in venom activity and prey resistance across 12 populations of Northern Pacific rattlesnakes and California ground squirrels, an interaction that has often been described as an arms race. Assays of venom function and squirrel resistance show substantial geographical variation (influenced by site elevation) in both venom metalloproteinase activity and resistance factor effectiveness. We demonstrate local adaptation in the effectiveness of rattlesnake venom to overcoming present squirrel resistance, suggesting that phenotype matching plays a role in the coevolution of these molecular traits. Further, the predator was the locally adapted antagonist in this interaction, arguing that rattlesnakes are evolutionarily ahead of their squirrel prey. Phenotype matching needs to be considered as an important mechanism influencing coevolution between venomous animals and resistant prey.

  14. Hoarding patterns in the southern flying squirrel (Glaucomys volans)

    SciTech Connect

    Clemmer, S.M.

    1984-05-01

    Southern flying squirrels, Glaucomys volans, were individually offered two size classes of pecans in a 1:1 ratio to establish preference. All but one squirrel preferred small pecans. As relative abundance of preferred food diminished to 0.10, squirrels switched preference. Absolute abundance of either food did not affect caching levels. A difficulty-of-retrieval experiment did not result in switching of preference. No effect of sex on hoarding was exhibited. There was an inverse correlation between individual storing effort and caching levels of the same squirrels tested as pairs, with individual non-storers showing increases in numbers of pecans stored. Animals that were active storers as individuals showed decreases when paired. Total number stored did not decrease significantly when squirrels were offered previously marked pecans. When offered own-marked and other-marked pecans, squirrels did not discriminate. 43 references, 3 figures, 6 tables.

  15. The Functional Organization and Cortical Connections of Motor Cortex in Squirrels

    PubMed Central

    Cooke, Dylan F.; Padberg, Jeffrey; Zahner, Tony

    2012-01-01

    Despite extraordinary diversity in the rodent order, studies of motor cortex have been limited to only 2 species, rats and mice. Here, we examine the topographic organization of motor cortex in the Eastern gray squirrel (Sciurus carolinensis) and cortical connections of motor cortex in the California ground squirrel (Spermophilus beecheyi). We distinguish a primary motor area, M1, based on intracortical microstimulation (ICMS), myeloarchitecture, and patterns of connectivity. A sensorimotor area between M1 and the primary somatosensory area, S1, was also distinguished based on connections, functional organization, and myeloarchitecture. We term this field 3a based on similarities with area 3a in nonrodent mammals. Movements are evoked with ICMS in both M1 and 3a in a roughly somatotopic pattern. Connections of 3a and M1 are distinct and suggest the presence of a third far rostral field, termed “F,” possibly involved in motor processing based on its connections. We hypothesize that 3a is homologous to the dysgranular zone (DZ) in S1 of rats and mice. Our results demonstrate that squirrels have both similar and unique features of M1 organization compared with those described in rats and mice, and that changes in 3a/DZ borders appear to have occurred in both lineages. PMID:22021916

  16. Metabolism of lithocholic and chenodeoxycholic acids in the squirrel monkey

    SciTech Connect

    Suzuki, H.; Hamada, M.; Kato, F.

    1985-09-01

    Metabolism of lithocholic acid (LCA) and chenodeoxycholic acid (CDCA) was studied in the squirrel monkey to clarify the mechanism of the lack of toxicity of CDCA in this animal. Radioactive LCA was administered to squirrel monkeys with biliary fistula. Most radioactivity was excreted in the bile in the form of unsulfated lithocholyltaurine. The squirrel monkey thus differs from humans and chimpanzees, which efficiently sulfate LCA, and is similar to the rhesus monkey and baboon in that LCA is poorly sulfated. When labeled CDCA was orally administered to squirrel monkeys, less than 20% of the dosed radioactivity was recovered as LCA and its further metabolites in feces over 3 days, indicating that bacterial metabolism of CDCA into LCA is strikingly less than in other animals and in humans. It therefore appears that LCA, known as a hepatotoxic secondary bile acid, is not accumulated in the squirrel monkey, not because of its rapid turnover through sulfation, but because of the low order of its production.

  17. Renal response to seven days of lower body positive pressure in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Churchill, Susanne; Pollock, David M.; Natale, Mary Ellen; Moore-Ede, Martin C.

    1987-01-01

    As a ground-based model for weightlessness, the response of the chair-trained squirrel monkey to lower body positive pressure (LBPP) was evaluated in a length of study similar to a typical Space Shuttle mission (7 days). Results were compared to time control experiments that included chair-sitting without exposure to LBPP. Chronic exposure to LBPP results in an acute diuretic and natriuretic response independent of changes in plasma aldosterone concentrations and produces a chronic reduction in fluid volume lasting the duration in the stimulus.

  18. How Habitat Features Shape Ground Squirrel (Urocitellus beldingi) Navigation

    PubMed Central

    Bruck, Jason N.; Mateo, Jill M.

    2010-01-01

    The purpose of this investigation was to determine whether Urocitellus beldingi from areas rich in beacons perform differently in a task of spatial memory compared with animals from beacon-thin areas. To assess the role of environmental experience in spatial memory, wild-born animals with several days of experience in the field were compared with animals born in a lab and with no experience in their original habitat. Over 2 summers subjects captured from beacon-dense and beacon-thin areas were tested in a radial maze interspersed with beacons, using number of trials to criterion as a measure of spatial memory. To evaluate the effect of landmark navigation, in year 2 juveniles were prevented from seeing outside the maze area. In both years animals from beacon-dense populations reached criterion faster than animals from beacon-thin populations, and a weak rearing effect was present in 1 year. Despite sex differences in adult spatial skills, no differences were found between males and females in the maze. This demonstrates variation in the navigation strategies of young U. beldingi, and highlights the need to evaluate spatial preferences as a function of population or ecology in addition to species and sex. PMID:20476817

  19. Squirrel Monkey Requirements for Chronic Acceleration

    NASA Technical Reports Server (NTRS)

    Fuller, Charles A.

    1996-01-01

    This study examined: (1) the ability of a small non-human primate to tolerate chronic centrifugation on a centrifuge with a radius of 0.9 m, and (2) the influence of centrifuge radius on the response of primates to hyperdynamic fields. Eight adult male squirrel monkeys were exposed to 1.5 g via centrifugation at two different radii (0.9 m and 3.0 m). Body temperature, activity, feeding and drinking were monitored. These primates did tolerate and adapt to 1.5G via centrifugation on either radius centrifuge. The results show, however, that centrifuge radius does have an effect on the responses of the primate to the hyperdynamic environment. Adaptation to the hyperdynamic environment occurred more quickly on the larger centrifuge. This study demonstrates that a small, non-human primate model, such as the squirrel monkey, could be used on a 0.9 m radius centrifuge such as is being considered by the NASA Space Station Program.

  20. Low-cost functional plasticity of TRPV1 supports heat tolerance in squirrels and camels

    PubMed Central

    Laursen, Willem J.; Merriman, Dana K.; Bagriantsev, Sviatoslav N.; Gracheva, Elena O.

    2016-01-01

    The ability to sense heat is crucial for survival. Increased heat tolerance may prove beneficial by conferring the ability to inhabit otherwise prohibitive ecological niches. This phenomenon is widespread and is found in both large and small animals. For example, ground squirrels and camels can tolerate temperatures more than 40 °C better than many other mammalian species, yet a molecular mechanism subserving this ability is unclear. Transient receptor potential vanilloid 1 (TRPV1) is a polymodal ion channel involved in the detection of noxious thermal and chemical stimuli by primary afferents of the somatosensory system. Here, we show that thirteen-lined ground squirrels (Ictidomys tridecemlineatus) and Bactrian camels (Camelus ferus) express TRPV1 orthologs with dramatically reduced temperature sensitivity. The loss of sensitivity is restricted to temperature and does not affect capsaicin or acid responses, thereby maintaining a role for TRPV1 as a detector of noxious chemical cues. We show that heat sensitivity can be reengineered in both TRPV1 orthologs by a single amino acid substitution in the N-terminal ankyrin-repeat domain. Conversely, reciprocal mutations suppress heat sensitivity of rat TRPV1, supporting functional conservation of the residues. Our studies suggest that squirrels and camels co-opt a common molecular strategy to adapt to hot environments by suppressing the efficiency of TRPV1-mediated heat detection at the level of somatosensory neurons. Such adaptation is possible because of the remarkable functional flexibility of the TRPV1 molecule, which can undergo profound tuning at the minimal cost of a single amino acid change. PMID:27638213

  1. Low-cost functional plasticity of TRPV1 supports heat tolerance in squirrels and camels.

    PubMed

    Laursen, Willem J; Schneider, Eve R; Merriman, Dana K; Bagriantsev, Sviatoslav N; Gracheva, Elena O

    2016-10-04

    The ability to sense heat is crucial for survival. Increased heat tolerance may prove beneficial by conferring the ability to inhabit otherwise prohibitive ecological niches. This phenomenon is widespread and is found in both large and small animals. For example, ground squirrels and camels can tolerate temperatures more than 40 °C better than many other mammalian species, yet a molecular mechanism subserving this ability is unclear. Transient receptor potential vanilloid 1 (TRPV1) is a polymodal ion channel involved in the detection of noxious thermal and chemical stimuli by primary afferents of the somatosensory system. Here, we show that thirteen-lined ground squirrels (Ictidomys tridecemlineatus) and Bactrian camels (Camelus ferus) express TRPV1 orthologs with dramatically reduced temperature sensitivity. The loss of sensitivity is restricted to temperature and does not affect capsaicin or acid responses, thereby maintaining a role for TRPV1 as a detector of noxious chemical cues. We show that heat sensitivity can be reengineered in both TRPV1 orthologs by a single amino acid substitution in the N-terminal ankyrin-repeat domain. Conversely, reciprocal mutations suppress heat sensitivity of rat TRPV1, supporting functional conservation of the residues. Our studies suggest that squirrels and camels co-opt a common molecular strategy to adapt to hot environments by suppressing the efficiency of TRPV1-mediated heat detection at the level of somatosensory neurons. Such adaptation is possible because of the remarkable functional flexibility of the TRPV1 molecule, which can undergo profound tuning at the minimal cost of a single amino acid change.

  2. Dulcin and saccharin taste in squirrel monkeys, rats, and men.

    PubMed

    Fisher, G L; Pfaffmann, C; Brown, E

    1965-10-22

    In a taste-preference comparison of sweetening agents, men reacted positively to two nonnutritive sweeteners, dulcin and sodium saccharin; rats preferred only saccharin and squirrel monkeys, only dulcin.

  3. 2. Light tower, view west towards Squirrel Island, south and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Light tower, view west towards Squirrel Island, south and east sides - Ram Island Light Station, Ram Island, south of Ocean Point & just north of Fisherman Island, marking south side of Fisherman Island Passage, Ocean Point, Lincoln County, ME

  4. Energetic costs of the winter arboreal microclimate: The gray squirrel in a tree

    NASA Astrophysics Data System (ADS)

    Byman, D.; Hay, D. B.; Bakken, G. S.

    1988-06-01

    Heated taxidermic mounts of the gray squirrel were used to analyze the thermal environment of a small arboreal endotherm. Changes in the standard operative temperature ( T es) calculated from the temperatures of heated and unheated mounts agreed well with the power consumption ( M-E) of mounts on the ground and on the wind-ward side of a 48-cm diameter tree trunk. As wind speed ( u) rose and sky solar radiation ( Q r) decreased, the windward side of the tree trunk became an increasingly more stressful thermal environment than the leeward side of the trunk or the ground, producing M-E differences of more than 30%. Although the M-E of a ground mount and a limb mount 4 m in the air are dependent on Q ras well as u, the ratio of the two value of M-E is independent of Q r, poorly predicted by u and well predicted by u 1/2.

  5. Whitebark pine, grizzly bears, and red squirrels

    USGS Publications Warehouse

    Mattson, D.J.; Kendall, K.C.; Reinhart, D.P.; Tomback, D.F.; Arno, S.F.; Keane, R.E.

    2001-01-01

    Appropriately enough, much of this book is devoted to discussing management challenges and techniques. However, the impetus for action—the desire to save whitebark pine (Pinus albicaulis)—necessarily arises from the extent to which we cherish it for its beauty and its connections with other things that we value. Whitebark pine is at the hub of a fascinating web of relationships. It is the stuff of great stories (cf. Quammen 1994). One of the more interesting of these stories pertains to the dependence of certain grizzly bear (Ursus arctos horribilis) populations on its seeds, and the role that red squirrels (Tamiasciurus hudsonicus) play as an agent of transfer between tree and bear.

  6. Amygdalar vocalization pathways in the squirrel monkey.

    PubMed

    Jürgens, U

    1982-06-10

    In 22 squirrel monkeys (Saimiri sciureus) vocalization-eliciting electrodes were implanted into the amygdala and along the trajectory of the stria terminalis. Then, lesions were placed in the stria terminalis, its bed nucleus, the ventral amygdalofugal pathway and several di- and mesencephalic structures in order to find out the pathways along which the amygdala exerts its vocalization-controlling influence. It was found that different call types are controlled by different pathways. Purring and chattering calls, which express a self-confident, challenging attitude and an attempt to recruit fellow-combatants in intra-specific mobbing, respectively, are controlled via the stria terminalis; alarm peep and groaning calls, in contrast, which indicate flight motivation and resentment, respectively, are triggered via the ventral amygdalofugal fibre bundle. Both pathways traverse the dorsolateral and dorsomedial hypothalamus, respectively, and unite in the periaqueductal grey of the midbrain.

  7. Motion sickness in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Ordy, J. M.; Brizzee, K. R.

    1980-01-01

    In this study of susceptibility to motion sickness the specific aims were to examine the effects of combined vertical rotation and horizontal acceleration, phenotype, sex, visual cues, morning and afternoon testing, and repeated test exposures on incidence, frequency, and latency of emetic responses. The highest emetic incidence of 89% with an emetic frequency of 2.0 during 60 min and a latency of 19 min from onset of testing occurred at 25 rpm and 0.5 Hz linear acceleration. Since the emetic responses were quite similar to man in eliciting motion stimuli it was concluded that the squirrel monkey represents a very suitable primate model for studies of motion and space sickness.

  8. Detection of squirrel poxvirus by nested and real-time PCR from red (Sciurus vulgaris) and grey (Sciurus carolinensis) squirrels

    PubMed Central

    2010-01-01

    Background Squirrel poxvirus (SQPV) is highly pathogenic to red squirrels (Sciurus vulgaris), and is a significant contributing factor to the local extinction of the species in most parts of England and Wales, where infection is endemic in Eastern grey squirrel (Sciurus carolinensis) populations. Although a nested PCR assay has been used successfully to study the epidemiology of SQPV, samples have a long processing time and the assay is not quantifiable. Results This project describes the design and optimization of a real-time PCR for SQPV. Comparison with the nested PCR showed the real-time assay to be more sensitive by one log and able to detect approximately 144 genome copies per mg of tissue. Conclusions The real-time PCR has been used to quantify viral genome load in tissues from diseased and apparently healthy red and grey squirrels, and suggests that the titre of virus in tissues from diseased red squirrels is considerably higher than that found even in a grey squirrel with cutaneous lesions. PMID:20529323

  9. Responses of squirrel monkeys to their experimentally modified mobbing calls

    NASA Astrophysics Data System (ADS)

    Fichtel, Claudia; Hammerschmidt, Kurt

    2003-05-01

    Previous acoustic analyses suggested emotion-correlated changes in the acoustic structure of squirrel monkey (Saimiri sciureus) vocalizations. Specifically, calls given in aversive contexts were characterized by an upward shift in frequencies, often accompanied by an increase in amplitude. In order to test whether changes in frequencies or amplitude are indeed relevant for conspecific listeners, playback experiments were conducted in which either frequencies or amplitude of mobbing calls were modified. Latency and first orienting response were measured in playback experiments with six adult squirrel monkeys. After broadcasting yaps with increased frequencies or amplitude, squirrel monkeys showed a longer orienting response towards the speaker than after the corresponding control stimuli. Furthermore, after broadcasting yaps with decreased frequencies or amplitude, squirrel monkeys showed a shorter orienting response towards the speaker than after the corresponding manipulated calls with higher frequencies or amplitude. These results suggest that changes in frequencies or amplitude were perceived by squirrel monkeys, indicating that the relationship between call structure and the underlying affective state of the caller agreed with the listener's assessment of the calls. However, a simultaneous increase in frequencies and amplitude did not lead to an enhanced response, compared to each single parameter. Thus, from the receiver's perspective, both call parameters may mutually replace each other.

  10. Environmental synchronizers of squirrel monkey circadian rhythms

    NASA Technical Reports Server (NTRS)

    Sulzman, F. M.; Fuller, C. A.; Moore-Ede, M. C.

    1977-01-01

    Various temporal signals in the environment were tested to determine if they could synchronize the circadian timing system of the squirrel monkey (Saimiri sciureus). The influence of cycles of light and dark, eating and fasting, water availability and deprivation, warm and cool temperature, sound and quiet, and social interaction and isolation on the drinking and activity rhythms of unrestrained monkeys was examined. In the absence of other time cues, 24-hr cycles of each of these potential synchronizers were applied for up to 3 wk, and the periods of the monkey's circadian rhythms were examined. Only light-dark cycles and cycles of food availability were shown to be entraining agents, since they were effective in determining the period and phase of the rhythmic variables. In the presence of each of the other environmental cycles, the monkey's circadian rhythms exhibited free-running periods which were significantly different from 24 hr with all possible phase relationships between the rhythms and the environmental cycles being examined.

  11. New world origins for haemoparasites infecting United Kingdom grey squirrels (Sciurus carolinensis), as revealed by phylogenetic analysis of bartonella infecting squirrel populations in England and the United States.

    PubMed

    Bown, K J; Ellis, B A; Birtles, R J; Durden, L A; Lello, J; Begon, M; Bennett, M

    2002-12-01

    Phylogenetic analyses of bartonella have suggested divergence between bartonellae that infect mammals native to the Old and New Worlds. We characterized bartonella isolated from Eastern grey squirrels (Sciurius carolinensis) in the United States and from grey and red squirrels (Sciurus vulgaris) in the United Kingdom by nucleotide sequence comparison (gltA and groEL). Isolates from grey squirrels in the United States and the United Kingdom were identical, and most similar to Bartonella vinsonii, a species associated with New World rodents. A single and novel bartonella genotype was obtained from all 12 red squirrel isolates. Although grey squirrels were first introduced into the United Kingdom over 125 years ago, they continue to be infected solely by the bartonella associated with grey squirrels native to the United States. These results illustrate that exotic species may be accompanied by the introduction and maintenance, over many generations, of their microparasites.

  12. A Variegated Squirrel Bornavirus Associated with Fatal Human Encephalitis.

    PubMed

    Hoffmann, Bernd; Tappe, Dennis; Höper, Dirk; Herden, Christiane; Boldt, Annemarie; Mawrin, Christian; Niederstraßer, Olaf; Müller, Tobias; Jenckel, Maria; van der Grinten, Elisabeth; Lutter, Christian; Abendroth, Björn; Teifke, Jens P; Cadar, Daniel; Schmidt-Chanasit, Jonas; Ulrich, Rainer G; Beer, Martin

    2015-07-09

    Between 2011 and 2013, three breeders of variegated squirrels (Sciurus variegatoides) had encephalitis with similar clinical signs and died 2 to 4 months after onset of the clinical symptoms. With the use of a metagenomic approach that incorporated next-generation sequencing and real-time reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR), the presence of a previously unknown bornavirus was detected in a contact squirrel and in brain samples from the three patients. Phylogenetic analyses showed that this virus, tentatively named variegated squirrel 1 bornavirus (VSBV-1), forms a lineage separate from that of the known bornavirus species. (Funded by the Federal Ministry of Food and Agriculture [Germany] and others.).

  13. Equivalence Between Squirrel Cage and Sheet Rotor Induction Motor

    NASA Astrophysics Data System (ADS)

    Dwivedi, Ankita; Singh, S. K.; Srivastava, R. K.

    2016-06-01

    Due to topological changes in dual stator induction motor and high cost of its fabrication, it is convenient to replace the squirrel cage rotor with a composite sheet rotor. For an experimental machine, the inner and outer stator stampings are normally available whereas the procurement of rotor stampings is quite cumbersome and is not always cost effective. In this paper, the equivalence between sheet/solid rotor induction motor and squirrel cage induction motor has been investigated using layer theory of electrical machines, so as to enable one to utilize sheet/solid rotor in dual port experimental machines.

  14. Biodiversity threats from outside to inside: effects of alien grey squirrel (Sciurus carolinensis) on helminth community of native red squirrel (Sciurus vulgaris).

    PubMed

    Romeo, Claudia; Ferrari, Nicola; Lanfranchi, Paolo; Saino, Nicola; Santicchia, Francesca; Martinoli, Adriano; Wauters, Lucas A

    2015-07-01

    Biological invasions are among the major causes of biodiversity loss worldwide, and parasites carried or acquired by invaders may represent an added threat to native species. We compared gastrointestinal helminth communities of native Eurasian red squirrels (Sciurus vulgaris) in the presence and absence of introduced Eastern grey squirrels (Sciurus carolinensis) to detect alterations induced by the alien species. In particular, we investigated whether spillover of a North American nematode Strongyloides robustus occurs and whether prevalence of a local parasite Trypanoxyuris sciuri in red squirrels is affected by grey squirrel presence. The probability of being infected by both parasites was significantly higher in areas co-inhabited by the alien species, where 61 % of examined red squirrels (n = 49) were infected by S. robustus and 90 % by T. sciuri. Conversely, in red-only areas, the two parasites infected only 5 and 70 % of individuals (n = 60). Overall, our findings support the hypothesis that red squirrels acquire S. robustus via spillover from the alien congener and suggest that invaders' presence may also indirectly affect infection by local parasites through mechanisms diverse than spill-back and linked to the increased competitive pressure to which red squirrels are subjected. These results indicate that the impact of grey squirrel on red squirrels may have been underestimated and highlight the importance of investigating variation in macroparasite communities of native species threatened by alien competitors.

  15. Fire, red squirrels, whitebark pine, and Yellowstone grizzly bears

    USGS Publications Warehouse

    Podruzny, Shannon; Reinhart, D.P.; Mattson, David J.

    1999-01-01

    Whitebark pine (Pinus albicaulis) habitats are important to Yellowstone grizzly bears (Ursus arctos) as refugia and sources of food. Ecological relationships between whitebark pine, red squirrels (Tamiasciurus hudsonicus), and grizzly bear use of pine seeds on Mt. Washburn in Yellowstone National Park, Wyoming, were examined during 1984-86. Following large-scale fires in 1988, we repeated the study in 1995-97 to examine the effects of fire on availability of whitebark pine seed in red squirrel middens and on bear use of middens. Half of the total length of the original line transects burned. We found no red squirrel middens in burned areas. Post-fire linear-abundance (no./km) of active squirrel middens that were pooled from burned and unburned areas decreased 27% compared to pre-fire abundance, but increased in unburned portions of some habitat types. Mean size of active middens decreased 54% post-fire. Use of pine seeds by bears (linear abundance of excavated middens) in pooled burned and unburned habitats decreased by 64%, likely due to the combined effects of reduced midden availability and smaller midden size. We discourage any further large-scale losses of seed producing trees from management-prescribed fires or timber harvesting until the effects of fire on ecological relationships in the whitebark pine zone are better understood.

  16. Polioencephalomalacia secondary to hypernatremia in squirrel monkeys (Saimiri sciureus).

    PubMed

    Macri, S M Cummings; Masek-Hammerman, K; Crowell, A M; Fenn, M S; Knight, H L; Westmoreland, S V; Miller, A D

    2014-05-01

    Squirrel monkeys (Saimiri spp) are one of the most consistently used New World primates in biomedical research and are increasingly being used in neuroscience research, including models of drug abuse and addiction. Spontaneous neurologic disease in the squirrel monkey is uncommonly reported but includes various infectious diseases as well as cerebral amyloidosis. Hypernatremia is an extremely serious condition of hyperosmolarity that occurs as a result of water loss, adipsia, or excess sodium intake. Neurologic effects of hypernatremia reflect the cellular dehydration produced by the shift of water from the intracellular fluid space into the hypertonic extracellular fluid space. Severe hypernatremia may result in cerebrocortical laminar necrosis (polioencephalomalacia) in human patients as well as in a number of domestic species, including pigs, poultry, and ruminants. We report the clinical, histopathologic, and immunohistochemical findings of polioencephalomalacia in 13 squirrel monkeys. Polioencephalomalacia in these animals was associated with hypernatremia that was confirmed by serum levels of sodium greater than 180 mmol/L (reference range, 134.0-154.0 mmol/L [mEq/L]). All animals had concurrent diseases or experimental manipulation that predisposed to adipsia. Immunohistochemical investigation using antibodies to neuronal nuclei (NeuN), CNPase, Iba-1, and CD31 revealed necrosis of predominantly cerebral cortical layers 3, 4, and 5 characterized by neuronal degeneration and loss, oligodendrocytic loss, microglial proliferation, and vascular reactivity. The squirrel monkey is exquisitely sensitive to hyperosmolar metabolic disruption and it is associated with laminar cortical necrosis.

  17. Mitochondrial Genetic Diversity of Eurasian Red Squirrels (Sciurus vulgaris) from Denmark.

    PubMed

    Madsen, Corrie L; Vilstrup, Julia T; Fernández, Ruth; Marchi, Nina; Håkansson, Bo; Krog, Mogens; Asferg, Tommy; Baagøe, Hans; Orlando, Ludovic

    2015-01-01

    Melanistic Eurasian red squirrels Sciurus vulgaris are commonly found on the Danish island of Funen. They are thought to represent native Danish squirrel types and are presently under threat from admixture with introduced red squirrels. In response, a conservation program was started in 2009 that involves the translocation of melanistic squirrels from Funen to the squirrel-free island of Langeland. Using mitochondrial DNA of 101 historical and modern samples from throughout Denmark, we assess for the first time population structure and mitochondrial genetic diversity of Danish squirrels compared to its larger pan-Eurasian distribution. We find that Danish squirrels have low levels of genetic diversity, especially melanistic individuals. Bayesian skyline reconstructions show that Danish squirrels have most probably experienced a severe bottleneck within the last 200 years. Also, fine-scale genetic structure was found between squirrels from the regions of Funen, Zealand and Jutland, which mimics the insular geography of Denmark. Additional nuclear DNA analyses will be required to determine the precise admixture levels between original Danish and introduced squirrels and to locate unmixed candidate populations for specific conservation efforts.

  18. Positive reinforcement training in squirrel monkeys using clicker training.

    PubMed

    Gillis, Timothy E; Janes, Amy C; Kaufman, Marc J

    2012-08-01

    Nonhuman primates in research environments experience regular stressors that have the potential to alter physiology and brain function, which in turn can confound some types of research studies. Operant conditioning techniques such as positive reinforcement training (PRT), which teaches animals to voluntarily perform desired behaviors, can be applied to improve behavior and reactivity. PRT has been used to train rhesus macaques, marmosets, and several other nonhuman primate species. To our knowledge, the method has yet to be used to train squirrel monkeys to perform complex tasks. Accordingly, we sought to establish whether PRT, utilizing a hand-box clicker (which emits a click sound that acts as the conditioned reinforcer), could be used to train adult male squirrel monkeys (Saimiri boliviensis, N = 14). We developed and implemented a training regimen to elicit voluntary participation in routine husbandry, animal transport, and injection procedures. Our secondary goal was to quantify the training time needed to achieve positive results. Squirrel monkeys readily learned the connection between the conditioned reinforcer (the clicker) and the positive reinforcer (food). They rapidly developed proficiency on four tasks of increasing difficulty: target touching, hand sitting, restraint training, and injection training. All subjects mastered target touching behavior within 2 weeks. Ten of 14 subjects (71%) mastered all tasks in 59.2 ± 2.6 days (range: 50-70 days). In trained subjects, it now takes about 1.25 min per monkey to weigh and administer an intramuscular injection, one-third of the time it took before training. From these data, we conclude that clicker box PRT can be successfully learned by a majority of squirrel monkeys within 2 months and that trained subjects can be managed more efficiently. These findings warrant future studies to determine whether PRT may be useful in reducing stress-induced experimental confounds in studies involving squirrel monkeys.

  19. Fatal Systemic Toxoplasma gondii Infection in a Red Squirrel (Sciurus vulgaris), a Swinhoe's Striped Squirrel (Tamiops swinhoei) and a New World Porcupine (Erethizontidae sp.).

    PubMed

    Fayyad, A; Kummerfeld, M; Davina, I; Wohlsein, P; Beineke, A; Baumgärtner, W; Puff, C

    2016-01-01

    Toxoplasmosis is a parasitic disease that affects man and animals worldwide. The primary hosts and major reservoir for Toxoplasma gondii are felids and the intermediate hosts are most warm-blooded animals including man. This report describes fatal toxoplasmosis in three different rodent species in Germany: a female red squirrel (Sciurus vulgaris) and a male Swinhoe's striped squirrel (Tamiops swinhoei), both kept as pets, and a female New World porcupine (Erethizontidae sp.) from a zoo. All three animals had multifocal necrotizing hepatitis. Additional findings included lymphohistiocytic and necrotizing myocarditis in the New World porcupine and the Swinhoe's striped squirrel, lymphohistiocytic encephalomyelitis in the New World porcupine and suppurative lymphadenitis in the red squirrel. Numerous tachyzoites were identified associated with the lesions. The diagnosis was confirmed by Toxoplasma. gondii immunohistochemistry and electron microscopy. This is the first report of toxoplasmosis in a New World porcupine and a Swinhoe's striped squirrel.

  20. Parapoxvirus causes a deleterious disease in red squirrels associated with UK population declines.

    PubMed Central

    Tompkins, Daniel M; Sainsbury, A W; Nettleton, P; Buxton, D; Gurnell, J

    2002-01-01

    The disease implications of novel pathogens need to be considered when investigating the ecological impact of species translocations on native fauna. Traditional explanations based on competition or predation may often not be the whole story. Evidence suggests that an emerging infectious disease, caused by a parapoxvirus, may be a significant component of the impact that the introduced grey squirrel has had on UK red squirrel populations. Here we validate the potential role of parapoxvirus by proving that the virus is highly pathogenic in the red squirrel while having no detectable effect on grey squirrel health. PMID:11886647

  1. Seasonal use of red-cockaded woodpecker cavities by southern flying squirrels.

    SciTech Connect

    Loeb, Susan C; Ruth, Deanna L

    2004-12-31

    Loeb, Susan C., and Deanna L. Ruth. 2004. Seasonal use of red-cockaded woodpecker cavities by southern flying squirrels. In: Red-cockaded woodpecker; Road to Recovery. Proceedings of the 4th Red-cockaded woodpecker Symposium. Ralph Costa and Susan J. Daniels, eds. Savannah, Georgia. January, 2003. Chapter 8. Cavities, Cavity Trees, and Cavity Communities. Pp 501-502. Abstract: Southern flying squirrels can significantly impact red-cockaded woodpecker reproductive success (Laves and Loeb 1999). Thus exclusion or removal of flying squirrels from red-cockaded woodpecker cavities and clusters may be warranted in small woodpecker populations (U.S. Fish and Wildlife Service 2003). However, development of effective and efficient protocols for southern flying squirrel control requires an understanding of the seasonal dynamics of southern flying squirrel cavity use. Most studies of southern flying squirrel use of red-cockaded woodpecker cavities have been conducted during spring (e.g., Harlow and Lennartz 1983, Rudolph et al. 1990a, Loeb 1993) and no studies have examined the effects of long term flying squirrel control on subsequent cavity use. The objectives of this study were to determine: (1) whether flying squirrel use of red-cockaded woodpecker cavities varies with season or cavity type, and (2) the long term effect of continuous squirrel removal.

  2. Motion Sickness-Induced Food Aversions in the Squirrel Monkey

    NASA Technical Reports Server (NTRS)

    Roy, M. Aaron; Brizzee, Kenneth R.

    1979-01-01

    Conditioned aversions to colored, flavored water were established in Squirrel monkeys (Saimiri sciureus) by following consumption with 90 min of simultaneous rotational and vertical stimulation. The experimental group (N= 13) drank significantly less of the green, almond-flavored test solution than did the control group (N=14) during three post-treatment preference testing days. Individual differences were noted in that two experimental monkeys readily drank the test solution after rotational stimulation. Only two of the experimental monkeys showed emesis during rotation, yet 10 monkeys in this group developed an aversion. These results suggest that: (1) motion sickness can be readily induced in Squirrel monkeys with simultaneous rotational and vertical stimulation, and (2) that conditioned food aversions are achieved in the absence of emesis in this species.

  3. Detection of hemagglutinins in cultures of squirrel monkey intestinal trichomonads.

    PubMed Central

    Pindak, F F; Gardner, W A; Mora de Pindak, M; Abee, C R

    1987-01-01

    Intestinal trichomonads are very common inhabitants of captive squirrel monkeys. In evaluating the potential pathogenicity of these organisms, we encountered hitherto unknown hemagglutinins in their culture fluids. The cytopathic effect associated with a number of the isolates resembled that caused by vacuolating viruses. We have ruled out conventional viruses as the cause of the cytopathic effect and as the source of the hemagglutinin. The agglutinin has some of the basic characteristics of lectins. Parallel experiments demonstrated agglutination of erythrocytes from squirrel monkeys, humans, dogs, cats, guinea pigs, and horses, with the first two types being the most sensitive. Relatively less agglutination was seen with rat erythrocytes. Agglutination of sheep, rabbit, chicken, and bovine erythrocytes was virtually absent. Images PMID:3571468

  4. Hemodynamic effects of barnidipine hydrochloride in conscious squirrel monkeys.

    PubMed

    Shibasaki, M; Inagaki, O; Takenaka, T

    1994-05-01

    1. The effects of barnidipine, a new dihydropyridine Ca2+ antagonist, on cardiovascular and renin-angiotensin-aldosterone systems were investigated in conscious squirrel monkeys. 2. Barnidipine (0.3-3 mg/kg p.o.) produced a dose-related decrease in systolic blood pressure. The hypotensive action after 3 mg/kg p.o. lasted more than 8 hr. 3. Barnidipine increased heart rate, but did not affect the PQ-interval of the electrocardiograph. 4. Barnidipine (1 and 3 mg/kg p.o.) increased plasma renin activity dose-dependently. However, it had no significant effect on plasma aldosterone concentration. 5. These results indicate that barnidipine produces a sustained hypotension without affecting atrioventricular conduction time and plasma aldosterone concentration in conscious squirrel monkeys.

  5. Eye-head coordination during optokinetic stimulation in squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Kubo, T.; Igarashi, M.; Jensen, D. W.; Homick, J. L.

    1981-01-01

    Head and eye movements in the yaw plane were recorded during and after optokinetic stimulation in squirrel monkeys. 1) Phasic or tonic head deviations to the side of the ocular quick phase occurred in 94% of total recordings (n = 50) during the perstimulus period, and in 75% of recordings (n = 49) during the poststimulus period. Magnitude of mean head deviation was significantly different between perstimulus and poststimulus periods. 2) Head nystagmus associated with eye nystagmus was consistently observed in seven of nine squirrel monkeys during optokinetic stimulation. Squirrel monkeys are thereby less prone to display head nystagmus than either guinea pigs, pigeons or chickens. 3) Slow phase speeds of coupled head and eye nystagmus were subjected to statistical analysis. A highly significant negative correlation was found between slow phase head and eye speeds. The correlation coefficient was - 0.81 at 60 degrees / sec stimulus (n = 119) and -0.72 at 100 degrees / sec stimulus (n = 131). The gaze speed, calculated by summing the head and eye speeds, was 59.1 plus or minus 6.8 / sec at 60 degrees / sec and 92.2 plus or minus 11.4 at 100 degrees / sec stimulus. There was no significant difference between the gaze speed in a free head condition and the eye speed when the head was fixed.

  6. Architectonic subdivisions of neocortex in the grey squirrel (Sciurus carolinensis)

    PubMed Central

    Wong, Peiyan; Kaas, Jon H.

    2010-01-01

    Squirrels are highly visual mammals with an expanded cortical visual system and a number of well-differentiated architectonic fields. In order to describe and delimit cortical fields, subdivisions of cortex were reconstructed from serial brain sections cut in the coronal, sagittal, or horizontal planes. Architectonic characteristics of cortical areas were visualized after brain sections were processed with immunohistochemical and histochemical procedures for revealing parvalbumin, calbindin, neurofilament protein, vesicle glutamate transporter 2, limbic-associated membrane protein, synaptic zinc, cytochrome oxidase, myelin or Nissl substance. In general, these different procedures revealed similar boundaries between areas, suggesting that functionally relevant borders were being detected. The results allowed a more precise demarcation of previously identified areas as well as the identification of areas that had not been previously described. Primary sensory cortical areas characterized by sparse zinc staining of layer 4, as thalamocortical terminations lack zinc, as well as by layer 4 terminations rich in parvalbumin and vesicle glutamate transporter 2. Primary areas also expressed higher levels of cytochrome oxidase and myelin. Primary motor cortex was associated with large SMI-32 labeled pyramidal cells in layers 3 and 5. Our proposed organization of cortex in grey squirrels includes both similarities and differences to the proposed of cortex in other rodents such as mice and rats. The presence of a number of well-differentiated cortical areas in squirrels may serve as a guide to the identification of homologous fields in other rodents, as well as a useful guide in further studies of cortical organization and function. PMID:18780299

  7. Red Squirrel Middens Influence Abundance but Not Diversity of Other Vertebrates

    PubMed Central

    Posthumus, Erin E.; Koprowski, John L.; Steidl, Robert J.

    2015-01-01

    Some animals modify the environment in ways that can influence the resources available to other species. Because red squirrels (Tamiasciurus hudsonicus) create large piles of conifer-cone debris (middens) in which they store cones, squirrels concentrate resources that might affect biodiversity locally. To determine whether other animals are attracted to midden sites beyond their affinity for the same resources that attract red squirrels, we assessed associations between middens, mammals, and birds at population and community levels. We surveyed 75 middens where residency rates of red squirrels varied during the previous five years; sampling along this residency gradient permitted us to evaluate the influence of resources at middens beyond the influence of a resident squirrel. At each location, we quantified vegetation, landscape structure, abundance of conifer cones, and midden structure, and used capture–recapture, distance sampling, and remote cameras to quantify presence, abundance, and species richness of mammals and birds. Red squirrels and the resources they concentrated at middens influenced mammals and birds at the population scale and to a lesser extent at the community scale. At middens with higher residency rates of red squirrels, richness of medium and large mammals increased markedly and species richness of birds increased slightly. After accounting for local forest characteristics, however, only species richness of medium-to-large mammals was associated with a red squirrel being resident during surveys. In areas where red squirrels were resident during surveys or in areas with greater amounts of resources concentrated by red squirrels, abundances of two of four small mammal species and two of four bird species increased. We conclude that the presence of this ecosystem modifier and the resources it concentrates influence abundance of some mammals and birds, which may have implications for maintaining biodiversity across the wide geographic range

  8. Red squirrel middens influence abundance but not diversity of other vertebrates.

    PubMed

    Posthumus, Erin E; Koprowski, John L; Steidl, Robert J

    2015-01-01

    Some animals modify the environment in ways that can influence the resources available to other species. Because red squirrels (Tamiasciurus hudsonicus) create large piles of conifer-cone debris (middens) in which they store cones, squirrels concentrate resources that might affect biodiversity locally. To determine whether other animals are attracted to midden sites beyond their affinity for the same resources that attract red squirrels, we assessed associations between middens, mammals, and birds at population and community levels. We surveyed 75 middens where residency rates of red squirrels varied during the previous five years; sampling along this residency gradient permitted us to evaluate the influence of resources at middens beyond the influence of a resident squirrel. At each location, we quantified vegetation, landscape structure, abundance of conifer cones, and midden structure, and used capture-recapture, distance sampling, and remote cameras to quantify presence, abundance, and species richness of mammals and birds. Red squirrels and the resources they concentrated at middens influenced mammals and birds at the population scale and to a lesser extent at the community scale. At middens with higher residency rates of red squirrels, richness of medium and large mammals increased markedly and species richness of birds increased slightly. After accounting for local forest characteristics, however, only species richness of medium-to-large mammals was associated with a red squirrel being resident during surveys. In areas where red squirrels were resident during surveys or in areas with greater amounts of resources concentrated by red squirrels, abundances of two of four small mammal species and two of four bird species increased. We conclude that the presence of this ecosystem modifier and the resources it concentrates influence abundance of some mammals and birds, which may have implications for maintaining biodiversity across the wide geographic range

  9. Evolution of genome organizations of squirrels (Sciuridae) revealed by cross-species chromosome painting.

    PubMed

    Li, Tangliang; O'Brien, Patricia C M; Biltueva, Larisa; Fu, Beiyuan; Wang, Jinhuan; Nie, Wenhui; Ferguson-Smith, Malcolm A; Graphodatsky, Alexander S; Yang, Fengtang

    2004-01-01

    With complete sets of chromosome-specific painting probes derived from flow-sorted chromosomes of human and grey squirrel (Sciurus carolinensis), the whole genome homologies between human and representatives of tree squirrels (Sciurus carolinensis, Callosciurus erythraeus), flying squirrels (Petaurista albiventer) and chipmunks (Tamias sibiricus) have been defined by cross-species chromosome painting. The results show that, unlike the highly rearranged karyotypes of mouse and rat, the karyotypes of squirrels are highly conserved. Two methods have been used to reconstruct the genome phylogeny of squirrels with the laboratory rabbit (Oryctolagus cuniculus) as the out-group: (1) phylogenetic analysis by parsimony using chromosomal characters identified by comparative cytogenetic approaches; (2) mapping the genome rearrangements onto recently published sequence-based molecular trees. Our chromosome painting results, in combination with molecular data, show that flying squirrels are phylogenetically close to New World tree squirrels. Chromosome painting and G-banding comparisons place chipmunks (Tamias sibiricus ), with a derived karyotype, outside the clade comprising tree and flying squirrels. The superorder Glires (orde Rodentia + order Lagomorpha) is firmly supported by two conserved syntenic associations between human chromosomes 1 and 10p homologues, and between 9 and 11 homologues.

  10. Effects of visitor numbers on captive European red squirrels (Sciurus vulgaris) and impacts on visitor experience.

    PubMed

    Woolway, Eleanor E; Goodenough, Anne E

    2017-02-21

    Visitors to zoological collections can have substantial effects on captive animals that vary according to species, enclosure design, visitor proximity, and husbandry methods. One particularly intense form of visitor interaction occurs in immersive exhibits such as walk-through enclosures. Such enclosures are increasingly common but effects on animal behavior are currently understudied. Here, the behavior of captive European red squirrels (Sciurus vulgaris) is studied in relation to visitor numbers in a walk-through enclosure. We also quantify the correlation between squirrel encounters and visitor experience. Interaction with humans increased significantly as the number of visitors inside the enclosure increased. The number of children present significantly increased locomotion and decreased eating, possibly due to disturbance and squirrels moving away from busy areas. By contrast, the number of adults significantly increased eating and decreased inactivity due to squirrels approaching visitors. The positive reinforcement training used by the keepers (offering food rewards to the squirrels for coming to them to allow routine medical checks) meant that squirrels associated adults with food opportunities. Squirrel encounter rate (number of squirrels seen by each group of visitors) was significantly affected by the number of adults and visitor duration (positive relationships) and noise as perceived by visitors (negative relationship). Encounter rate was positively correlated with overall visitor experience. Our results indicate that visitors affect behavior but this effect is influenced by husbandry methods. It is vital that visitors, especially children, minimize noise, and move slowly in the enclosure, both for the sake of the animals and their own experience.

  11. WEST NILE VIRUS INFECTION IN TREE SQUIRRELS (RODENTIA: SCIURIDAE) IN CALIFORNIA, 2004–2005

    PubMed Central

    PADGETT, KERRY A.; REISEN, WILLIAM K.; KAHL-PURCELL, NICOLE; FANG, YING; CAHOON-YOUNG, BARBARA; CARNEY, RYAN; ANDERSON, NANCY; ZUCCA, LYNDA; WOODS, LESLIE; HUSTED, STAN; KRAMER, VICKI L.

    2007-01-01

    West Nile virus (WNV) transmission generally involves a mosquito vector and an avian reservoir host, with mammals as incidental hosts. Although most mammalian WNV infections cause low or no morbidity or mortality, tree squirrels are susceptible to WNV-associated neurologic disease with infection prevalence comparable to that in dead birds. Positive species included fox squirrel (Sciurus niger), western gray squirrel (S. griseus), and eastern gray squirrel (S. carolinensis). Kidney tissue (dissected and swabbed), and oropharyngeal (oral) swab samples from tree squirrels submitted by California vector control and rehabilitation agencies were tested by reverse transcription–polymerase chain reaction; cycle threshold values were similar for all three samples, ranging from 21.9 to 26.5. Kidney tissue was more sensitive than oral swabs for detecting WNV in squirrels. Three of 36 live neurologic tree squirrels had viremia approximately 5 log10 plaque-forming units/mL or greater, similar to WNV-infected birds. Tree squirrels are useful in WNV surveillance and provide localized evidence of WNV transmission to mammals. PMID:17488896

  12. Woodland fragmentation affects space use of Eurasian red squirrels

    NASA Astrophysics Data System (ADS)

    Verbeylen, Goedele; Wauters, Lucas A.; De Bruyn, Luc; Matthysen, Erik

    2009-01-01

    When habitats become fragmented, variation in patch size and quality are expected to impose changes on the spacing pattern and social organization of animal populations. General theory predicts different possible responses including shrinking home ranges (fission response), increasing range overlap (fusion) and incorporation of multiple patches in the home range (expansion response) as fragmentation increases. We studied space use and social organization in a metapopulation of red squirrels ( Sciurus vulgaris) in 15 woodland fragments differing in size and tree species composition. Home ranges and core areas of males were larger than females, and fragmentation had different and complex effects on the spacing pattern of both sexes. In food-supplemented patches, high densities led to increased intra-sexual overlap. In linear-shaped patches, squirrels used smaller home ranges and core areas and had lower male-male and male-female overlap levels, independent of patch quality or size. Home range and core area size of males increased with patch size, and male core areas overlapped extensively those of other males and females. Hence males seemed to show a fission response only in some patches. In contrast, home range and core area size of females was not related with patch size, but decreased with habitat quality, supporting predictions of a fusion response and intra-sexual defense of food-based core areas. Hence, where patch size and shape strongly affected space use of male red squirrels, social organization of females was only affected in small, food-supplemented patches, suggesting that the basic spatio-social organization of adult females is very resistant to fragmentation.

  13. Stereological assessment of normal Persian squirrels (Sciurus anomalus) kidney.

    PubMed

    Akbari, Mohsen; Goodarzi, Nader; Tavafi, Majid

    2017-03-01

    The functions of the mammalian kidney are closely related to its structure. This suggests that renal function can be completely characterized by accurate knowledge of its quantitative morphological features. The aim of this study was to investigate the histomorphometric features of the kidney using design-based and unbiased stereological methods in the Persian squirrel (Sciurus anomalus), which is the only representative of the Sciuridae family in the Middle East. The left kidneys of five animals were examined. Total volume of the kidney, cortex, and medulla were determined to be 960.75 ± 87.4, 754.31 ± 77.09 and 206.1 ± 16.89 mm(3), respectively. The glomerular number was 32844.03 ± 1069.19, and the total glomerular volume was estimated to be 36.7 ± 1.45 mm(3). The volume and length of the proximal convoluted tubule were estimated at 585.67 ± 60.7 mm(3) and 328.8 ± 14.8 m, respectively, with both values being greater than those reported in the rat kidney. The volume and length of the distal convoluted tubule were calculated at 122.34 ± 7.38 mm(3) and 234.4 ± 17.45 m, respectively, which are also greater than those reported in the rat kidney. Despite the comparable body weight, the total number and mean individual volume of glomeruli in the Persian squirrel kidney were greater than those in the rat kidney. Overall, the stereological variables of the kidneys elucidated in this study are exclusive to the Persian squirrel. Our findings, together with future renal physiological data, will contribute to a better understanding of the renal structure-function relationship in the Persian squirrel.

  14. [Responses of squirrel visual cortex neurons to patterned visual stimuli].

    PubMed

    Supin, A Ia

    1975-01-01

    The responses of visual cortical neurons to patterned visual stimuli were studied in squirrel Sciurus vulgaris. The direction selective, orientation-selective and non-selective neurons were observed. Most direction-selective and non-selective neurons were sensitive to high speeds of stimulus movement--hundreds deg/s. The direction-selective neurons exhibited their selectivity at such high speeds in spite of the short time of the stimulus movement through the receptive field. Orientation-selective neurons (with simple or complex receptive fields) were sensitive to lower speeds of the stimulus movement (tens deg/s). Some mechanisms of the properties described are discussed.

  15. The squirrel monkey as a candidate for space flight

    NASA Technical Reports Server (NTRS)

    Brizzee, K. R.; Ordy, J. M.; Kaack, B.

    1977-01-01

    Because of its size and other unique diurnal-primate characteristics, the squirrel monkey is used in: (1) actual bioflight missions, (2) in laboratory tests designed to clarify the risks to man during launch and recovery as well as in hazardous spaceflight environments; and (3) in the acquisition of data on unknown risks encountered in long duration space exploration. Pertinent data concerning samiri sciureus as described in published and unpublished reports are summarized. Topics include: taxonomy, ethology, life history, sensory-learning-motor capabilities in primate perspective, anatomy and physiology (including homeostatic adaptation to stress), susceptibility to environmental hazards, reproduction, care and clinical management, and previous use in aerospace biomedical research.

  16. Relative Roles of Grey Squirrels, Supplementary Feeding, and Habitat in Shaping Urban Bird Assemblages

    PubMed Central

    Bonnington, Colin; Gaston, Kevin J.; Evans, Karl L.

    2014-01-01

    Non-native species are frequently considered to influence urban assemblages. The grey squirrel Sciurus carolinensis is one such species that is widespread in the UK and is starting to spread across Europe; it predates birds’ nests and can compete with birds for supplementary food. Using distance sampling across the urbanisation intensity gradient in Sheffield (UK) we test whether urban grey squirrels influence avian species richness and density through nest predation and competition for supplementary food sources. We also assess how urban bird assemblages respond to supplementary feeding. We find that grey squirrels slightly reduced the abundance of breeding bird species most sensitive to squirrel nest predation by reducing the beneficial impact of woodland cover. There was no evidence that grey squirrel presence altered relationships between supplementary feeding and avian assemblage structure. This may be because, somewhat surprisingly, supplementary feeding was not associated with the richness or density of wintering bird assemblages. These associations were positive during the summer, supporting advocacy to feed birds during the breeding season and not just winter, but explanatory capacity was limited. The amount of green space and its quality, assessed as canopy cover, had a stronger influence on avian species richness and population size than the presence of grey squirrels and supplementary feeding stations. Urban bird populations are thus more likely to benefit from investment in improving the availability of high quality habitats than controlling squirrel populations or increased investment in supplementary feeding. PMID:25338062

  17. Relative roles of grey squirrels, supplementary feeding, and habitat in shaping urban bird assemblages.

    PubMed

    Bonnington, Colin; Gaston, Kevin J; Evans, Karl L

    2014-01-01

    Non-native species are frequently considered to influence urban assemblages. The grey squirrel Sciurus carolinensis is one such species that is widespread in the UK and is starting to spread across Europe; it predates birds' nests and can compete with birds for supplementary food. Using distance sampling across the urbanisation intensity gradient in Sheffield (UK) we test whether urban grey squirrels influence avian species richness and density through nest predation and competition for supplementary food sources. We also assess how urban bird assemblages respond to supplementary feeding. We find that grey squirrels slightly reduced the abundance of breeding bird species most sensitive to squirrel nest predation by reducing the beneficial impact of woodland cover. There was no evidence that grey squirrel presence altered relationships between supplementary feeding and avian assemblage structure. This may be because, somewhat surprisingly, supplementary feeding was not associated with the richness or density of wintering bird assemblages. These associations were positive during the summer, supporting advocacy to feed birds during the breeding season and not just winter, but explanatory capacity was limited. The amount of green space and its quality, assessed as canopy cover, had a stronger influence on avian species richness and population size than the presence of grey squirrels and supplementary feeding stations. Urban bird populations are thus more likely to benefit from investment in improving the availability of high quality habitats than controlling squirrel populations or increased investment in supplementary feeding.

  18. Macroparasite fauna of alien grey squirrels (Sciurus carolinensis): composition, variability and implications for native species.

    PubMed

    Romeo, Claudia; Wauters, Lucas A; Ferrari, Nicola; Lanfranchi, Paolo; Martinoli, Adriano; Pisanu, Benoît; Preatoni, Damiano G; Saino, Nicola

    2014-01-01

    Introduced hosts populations may benefit of an "enemy release" through impoverishment of parasite communities made of both few imported species and few acquired local ones. Moreover, closely related competing native hosts can be affected by acquiring introduced taxa (spillover) and by increased transmission risk of native parasites (spillback). We determined the macroparasite fauna of invasive grey squirrels (Sciurus carolinensis) in Italy to detect any diversity loss, introduction of novel parasites or acquisition of local ones, and analysed variation in parasite burdens to identify factors that may increase transmission risk for native red squirrels (S. vulgaris). Based on 277 grey squirrels sampled from 7 populations characterised by different time scales in introduction events, we identified 7 gastro-intestinal helminths and 4 parasite arthropods. Parasite richness is lower than in grey squirrel's native range and independent from introduction time lags. The most common parasites are Nearctic nematodes Strongyloides robustus (prevalence: 56.6%) and Trichostrongylus calcaratus (6.5%), red squirrel flea Ceratophyllus sciurorum (26.0%) and Holarctic sucking louse Neohaematopinus sciuri (17.7%). All other parasites are European or cosmopolitan species with prevalence below 5%. S. robustus abundance is positively affected by host density and body mass, C. sciurorum abundance increases with host density and varies with seasons. Overall, we show that grey squirrels in Italy may benefit of an enemy release, and both spillback and spillover processes towards native red squirrels may occur.

  19. Toxoplasmosis in a woodchuck (Marmota monax) and two American red squirrels (Tamiasciurus hudsonicus).

    PubMed

    Bangari, Dinesh S; Mouser, Pamela; Miller, Margaret A; Stevenson, Gregory W; Vemulapalli, Ramesh; Thacker, H Leon

    2007-11-01

    Toxoplasmosis was diagnosed in a woodchuck (Marmota monax) and 2 American red squirrels (Tamiasciurus hudsonicus). The woodchuck was euthanized by a wildlife rescue organization in New York after progressive clinical signs of head tilt, circling, and rapid weight loss. Necropsy examination revealed acute subdural hemorrhage over the right cerebral hemisphere. Histologic lesions included meningoencephalitis, myocarditis, and hepatitis. Protozoal cysts were present in affected and unaffected neuroparenchyma. The squirrels were found dead, emaciated, and moderately infested with fleas near a park in northern Indiana. In both squirrels, the lungs were consolidated with numerous nodules up to 2 mm in diameter. Histologically, pneumonia and encephalitis were associated with intracellular and free protozoa. Additional histologic lesions included multifocal lymphoplasmacytic encephalitis with intralesional protozoa in both squirrels. The protozoa were positive with Toxoplasma gondii-specific immunohistochemistry and had ultrastructural features consistent with T. gondii in both squirrels. A real-time polymerase chain reaction test using T. gondii-specific probes demonstrated protozoal DNA in the lung, brain, and kidney of the squirrels and in the brain and heart of the woodchuck. To the authors' knowledge, this is the first report of toxoplasmosis in woodchucks or American red squirrels. Because rodents are common near urban settlements, this finding underscores their role as important intermediate hosts for T. gondii.

  20. Macroparasite Fauna of Alien Grey Squirrels (Sciurus carolinensis): Composition, Variability and Implications for Native Species

    PubMed Central

    Romeo, Claudia; Wauters, Lucas A.; Ferrari, Nicola; Lanfranchi, Paolo; Martinoli, Adriano; Pisanu, Benoît; Preatoni, Damiano G.; Saino, Nicola

    2014-01-01

    Introduced hosts populations may benefit of an "enemy release" through impoverishment of parasite communities made of both few imported species and few acquired local ones. Moreover, closely related competing native hosts can be affected by acquiring introduced taxa (spillover) and by increased transmission risk of native parasites (spillback). We determined the macroparasite fauna of invasive grey squirrels (Sciurus carolinensis) in Italy to detect any diversity loss, introduction of novel parasites or acquisition of local ones, and analysed variation in parasite burdens to identify factors that may increase transmission risk for native red squirrels (S. vulgaris). Based on 277 grey squirrels sampled from 7 populations characterised by different time scales in introduction events, we identified 7 gastro-intestinal helminths and 4 parasite arthropods. Parasite richness is lower than in grey squirrel's native range and independent from introduction time lags. The most common parasites are Nearctic nematodes Strongyloides robustus (prevalence: 56.6%) and Trichostrongylus calcaratus (6.5%), red squirrel flea Ceratophyllus sciurorum (26.0%) and Holarctic sucking louse Neohaematopinus sciuri (17.7%). All other parasites are European or cosmopolitan species with prevalence below 5%. S. robustus abundance is positively affected by host density and body mass, C. sciurorum abundance increases with host density and varies with seasons. Overall, we show that grey squirrels in Italy may benefit of an enemy release, and both spillback and spillover processes towards native red squirrels may occur. PMID:24505348

  1. Behavioural responses of Eastern grey squirrels, Sciurus carolinensis, to cues of risk while foraging.

    PubMed

    Jayne, Kimberley; Lea, Stephen E G; Leaver, Lisa A

    2015-07-01

    Previous studies have shown that Eastern grey squirrels modify their behaviour while foraging to offset risks of social and predatory costs, but none have simultaneously compared whether such modifications are performed at a cost to foraging. The present study directly compares how grey squirrels respond to cues of these risks while foraging. We simulated social risk and predatory risk using acoustic playbacks of stimuli that grey squirrels might be exposed to at a foraging patch: calls of conspecifics, heterospecifics (competitor and non-competitor) and predators. We found that grey squirrels responded to predator, heterospecific competitor and conspecific playbacks by altering their foraging and vigilance behaviours. Foraging was most disrupted by increased vigilance when we played calls of predators. Squirrels' response to calls of heterospecific competitors did not differ from their response to conspecific calls, and they resumed foraging more quickly after both compared to predator calls: whereas they showed little response to calls of non-competitor heterospecifics and a white noise control. We conclude that squirrels respond differentially to calls made by conspecifics, heterospecific competitors and predators, with the most pronounced response being to calls of predators. We suggest that squirrels may view conspecific and corvid vocalisations as cues of potential conflict while foraging, necessitating increased vigilance.

  2. Mesoamerican tree squirrels evolution (Rodentia: Sciuridae): a molecular phylogenetic analysis.

    PubMed

    Villalobos, Federico; Gutierrez-Espeleta, Gustavo

    2014-06-01

    The tribe Sciurini comprehends the genera Sciurus, Syntheosiurus, Microsciurus, Tamiasciurus and Rheinthrosciurus. The phylogenetic relationships within Sciurus have been only partially done, and the relationship between Mesoamerican species remains unsolved. The phylogenetic relationships of the Mesoamerican tree squirrels were examined using molecular data. Sequence data publicly available (12S, 16S, CYTB mitochondrial genes and IRBP nuclear gene) and cytochrome B gene sequences of four previously not sampled Mesoamerican Sciurus species were analyzed under a Bayesian multispecies coalescence model. Phylogenetic analysis of the multilocus data set showed the neotropical tree squirrels as a monophyletic clade. The genus Sciurus was paraphyletic due to the inclusion of Microsciurus species (M. alfari and M. flaviventer). The South American species S. aestuans and S. stramineus showed a sister taxa relationship. Single locus analysis based on the most compact and complete data set (i.e. CYTB gene sequences), supported the monophyly of the South American species and recovered a Mesoamerican clade including S. aureogaster, S. granatensis and S. variegatoides. These results corroborated previous findings based on cladistic analysis of cranial and post-cranial characters. Our data support a close relationship between Mesoamerican Sciurus species and a sister relationship with South American species, and corroborates previous findings in relation to the polyphyly of Microsciurus and Syntheosciurus paraphyly.

  3. Validation of DTI tractography-based measures of primary motor area connectivity in the squirrel monkey brain.

    PubMed

    Gao, Yurui; Choe, Ann S; Stepniewska, Iwona; Li, Xia; Avison, Malcolm J; Anderson, Adam W

    2013-01-01

    Diffusion tensor imaging (DTI) tractography provides noninvasive measures of structural cortico-cortical connectivity of the brain. However, the agreement between DTI-tractography-based measures and histological 'ground truth' has not been quantified. In this study, we reconstructed the 3D density distribution maps (DDM) of fibers labeled with an anatomical tracer, biotinylated dextran amine (BDA), as well as DTI tractography-derived streamlines connecting the primary motor (M1) cortex to other cortical regions in the squirrel monkey brain. We evaluated the agreement in M1-cortical connectivity between the fibers labeled in the brain tissue and DTI streamlines on a regional and voxel-by-voxel basis. We found that DTI tractography is capable of providing inter-regional connectivity comparable to the neuroanatomical connectivity, but is less reliable measuring voxel-to-voxel variations within regions.

  4. Mandible shape and dwarfism in squirrels (Mammalia, Rodentia): interaction of allometry and adaptation

    NASA Astrophysics Data System (ADS)

    Hautier, Lionel; Fabre, Pierre-Henri; Michaux, Jacques

    2009-06-01

    Squirrels include several independent lineages of dwarf forms distributed into two ecological groups: the dwarf tree and flying squirrels. The mandible of dwarf tree squirrels share a highly reduced coronoid process and a condylar process drawn backwards. Dwarf flying squirrels on the other hand, have an elongated coronoid process and a well-differentiated condylar process. To interpret such a difference, Elliptic Fourier Transform was used to evaluate how mandible shape varies with dwarfism in sciurids. The results obtained show that this clear-cut difference cannot be explained by a simple allometric relationship in relation with size decrease. We concluded that the retention of anteriorly positioned eye sockets, in relation with distance estimation, allowed the conservation of a well-differentiated coronoid process in all flying species, despite the trend towards its reduction observed among sciurids as their size decreases.

  5. Object permanence in orangutans (Pongo pygmaeus) and squirrel monkeys (Saimiri sciureus).

    PubMed

    de Blois, S T; Novak, M A; Bond, M

    1998-06-01

    The authors tested orangutans (Pongo pygmaeus) and squirrel monkeys (Saimiri sciureus) on object permanence tasks. In Experiment 1, orangutans solved all visible displacements and most invisible displacements except those involving movements into 2 boxes successively. In Experiment 2, performance of orangutans on double invisible displacements and control displacements (assessing simple strategies) was compared. Orangutans did not use the simple strategy of selecting the box visited last by the experimenter. Instead, poorer performance on double invisible displacements may have been related to increased memory requirements. In Experiment 3, squirrel monkeys were tested using the procedure of Experiment 1. Squirrel monkeys solved visible but did not comprehend invisible displacements. Results suggest that orangutans but not squirrel monkeys possess Stage 6 object permanence capabilities.

  6. Subgingival microbiota in squirrel monkeys with naturally occurring periodontal diseases.

    PubMed Central

    Beem, J E; Hurley, C G; Magnusson, I; McArthur, W P; Clark, W B

    1991-01-01

    The squirrel monkey (Saimiri sciureus) has been proposed as an in vivo model for the study of subgingival colonization by suspected periodontopathogens, such as black-pigmented porphyromonads and prevotellas (BP/P). However, the indigenous microbiota of the squirrel monkey has not been well described. Therefore, in order to more fully characterize the oral microbiota of these animals, we studied two groups of squirrel monkeys from widely different sources. Group I consisted of 50 breeding colony monkeys ranging in age from 9 months to over 6 years which had been raised in captivity; group II consisted of 16 young sexually mature monkeys recently captured in the wild in Guyana. Group I animals in captivity had developed moderate to severe gingivitis, with a mean gingival index (GI) of 2.6; 52% of the sites bled, 26% had detectable calculus, and 83% had detectable BP/P. A group I subset (six animals), for which predominant cultivable microbiota was described, had a mean GI of 2.4. Colony morphology enumeration revealed that five of the six subset animals were detectably colonized with BP/P (range, 0 to 16.9%) and Actinobacillus actinomycetemcomitans (range, 0 to 3.9%); all subset animals were colonized with Fusobacterium species (range, 0.8 to 3.6%), Actinomyces species (range, 2.3 to 11%), and gram-positive cocci (range, 1.4 to 21.4%). Predominant cultivable microbiota results revealed the presence of many bacterial species commonly found in the human gingival sulcus. At baseline, group II animals were clinically healthy and had a mean GI of 1.4; 67% of the sites bled and 2.1% had calculus, and none of the animals had detectable BP/P. Neisseriae were very common in noninflamed sites. Subsequently, when inflamed sites were compared with noninflamed sites in group II animals after they had been maintained in captivity for 6 months, inflamed sites exhibited a more complex microbiota and increased proportions of gram-negative rods and asaccharolytic bacteria. PMID

  7. Dissecting the mechanisms of squirrel monkey (Saimiri boliviensis) social learning

    PubMed Central

    Holmes, AN; Williams, LE; Brosnan, SF

    2013-01-01

    Although the social learning abilities of monkeys have been well documented, this research has only focused on a few species. Furthermore, of those that also incorporated dissections of social learning mechanisms, the majority studied either capuchins (Cebus apella) or marmosets (Callithrix jacchus). To gain a broader understanding of how monkeys gain new skills, we tested squirrel monkeys (Saimiri boliviensis) which have never been studied in tests of social learning mechanisms. To determine whether S. boliviensis can socially learn, we ran “open diffusion” tests with monkeys housed in two social groups (N = 23). Over the course of 10 20-min sessions, the monkeys in each group observed a trained group member retrieving a mealworm from a bidirectional task (the “Slide-box”). Two thirds (67%) of these monkeys both learned how to operate the Slide-box and they also moved the door significantly more times in the direction modeled by the trained demonstrator than the alternative direction. To tease apart the underlying social learning mechanisms we ran a series of three control conditions with 35 squirrel monkeys that had no previous experience with the Slide-box. The first replicated the experimental open diffusion sessions but without the inclusion of a trained model, the second was a no-information control with dyads of monkeys, and the third was a ‘ghost’ display shown to individual monkeys. The first two controls tested for the importance of social support (mere presence effect) and the ghost display showed the affordances of the task to the monkeys. The monkeys showed a certain level of success in the group control (54% of subjects solved the task on one or more occasions) and paired controls (28% were successful) but none were successful in the ghost control. We propose that the squirrel monkeys’ learning, observed in the experimental open diffusion tests, can be best described by a combination of social learning mechanisms in concert; in this

  8. Dissecting the mechanisms of squirrel monkey (Saimiri boliviensis) social learning.

    PubMed

    Hopper, Lm; Holmes, An; Williams, LE; Brosnan, Sf

    2013-01-01

    Although the social learning abilities of monkeys have been well documented, this research has only focused on a few species. Furthermore, of those that also incorporated dissections of social learning mechanisms, the majority studied either capuchins (Cebus apella) or marmosets (Callithrix jacchus). To gain a broader understanding of how monkeys gain new skills, we tested squirrel monkeys (Saimiri boliviensis) which have never been studied in tests of social learning mechanisms. To determine whether S. boliviensis can socially learn, we ran "open diffusion" tests with monkeys housed in two social groups (N = 23). Over the course of 10 20-min sessions, the monkeys in each group observed a trained group member retrieving a mealworm from a bidirectional task (the "Slide-box"). Two thirds (67%) of these monkeys both learned how to operate the Slide-box and they also moved the door significantly more times in the direction modeled by the trained demonstrator than the alternative direction. To tease apart the underlying social learning mechanisms we ran a series of three control conditions with 35 squirrel monkeys that had no previous experience with the Slide-box. The first replicated the experimental open diffusion sessions but without the inclusion of a trained model, the second was a no-information control with dyads of monkeys, and the third was a 'ghost' display shown to individual monkeys. The first two controls tested for the importance of social support (mere presence effect) and the ghost display showed the affordances of the task to the monkeys. The monkeys showed a certain level of success in the group control (54% of subjects solved the task on one or more occasions) and paired controls (28% were successful) but none were successful in the ghost control. We propose that the squirrel monkeys' learning, observed in the experimental open diffusion tests, can be best described by a combination of social learning mechanisms in concert; in this case, those

  9. Green foliage losses from ponderosa pines induced by Abert squirrels and snowstorms: A comparison. [Sciurus aberti; Pinus pondersosa

    SciTech Connect

    Allred, W.S.; Gaud, W.S. )

    1993-01-01

    Abert squirrels (Sciurus aberti) are obligate herbivores on ponderosa pine (Pinus ponderosa). The inner bark of pine shoots is considered one of the predominant food resources obtained by foraging squirrels. As squirrels forage for this resource they induce green needle losses from chosen feed trees. Amounts of induced green needle losses appear to vary according to the availability of alternative foods and squirrel population densities. Weather also induces green needle losses to ponderosa pines. Results of this study indicate that, at least in some years, heavy snowstorms can induce greater amounts of green needle losses than squirrels. Squirrel herbivory was not indicated as a factor in any tree mortality. However, losses due to snowstorms are more severe since they may cause the actual depletion of trees in the forest because of the tree mortality they inflict.

  10. Status and habitat relationships of northern flying squirrels on Mount Desert Island, Maine

    USGS Publications Warehouse

    O'Connell, A.F.; Servello, F.; Higgins, J.; Halteman, W.

    2001-01-01

    Northern (Glaucomys sabrinus) and southern (G. volans) flying squirrels occur in Maine, but there is uncertainty about range overlap in southcentral Maine where the southern flying squirrel reaches its geographic range limit. We surveyed flying squirrels on Mount Desert Island (MDI), located along the central Maine coast, to update the current status and distribution of these species. We captured only northern flying squirrels, and populations (> 2 individuals) were located in two conifer stands and one mixed conifer-hardwood stand. All three stands were located in relatively older forests, outside a large area burned in a 1947 fire. Tree diameters were similar between trap stations with and without captures, under-story density was low overall, and there was a trend of higher seedling density at capture locations. Low understory density may allow squirrels more effective gliding movements between trees, which may enhance predator avoidance. Although the southern flying squirrel was reported from MDI numerous times during the 20th century, no voucher specimens exist, and species identification and localities have been poorly documented. Future surveys on MDI should consider collection of voucher specimens to validate subsequent survey efforts and effectively document changes in local biodiversity.

  11. Movements of northern flying squirrels in different-aged forest stands of western Oregon

    USGS Publications Warehouse

    Martin, K.J.; Anthony, R.G.

    1999-01-01

    In western Oregon, northern flying squirrels (Glaucomys sabrinus) are the primary prey species for northern spotted owls (Strix occidentalis caurina), an old-growth associated species. To assess differences between old-growth and second-growth habitat, we livetrapped and radiotagged 39 northern flying squirrels to estimate their home range sizes and describe movements in 2 old-growth and 2 second-growth conifer forest stands in the Cascade Mountains of central Oregon. Sampling periods were summer and fall of 1991-92. Home range sizes averaged 4.9 ha and did not differ (P > 0.30) between the 2 stand types. Male northern flying squirrels had larger (P ??? 0.03) mean home ranges (5.9 ?? 0.8 ha; ?? ?? SE; n = 20) than females (3.9 ?? 0.4 ha; n = 19). Northern flying squirrel movement distances between successive, noncorrelated telemetry locations averaged 71 m (n = 1,090). No correlation was found between distances moved and stand type or sex. Northern flying squirrel's home range sizes, movements, and densities were similar between the 2 stand types. We suggest abundance and movements of northern flying squirrels are not influencing the preferential selection of oldgrowth forests by northern spotted owls.

  12. Genetic variation in natural and translocated populations of the endangered Delmarva fox squirrel (Sciurus niger cinereus)

    USGS Publications Warehouse

    Lance, S.L.; Maldonado, J.E.; Bocetti, C.I.; Pattee, O.H.; Ballou, J.D.; Fleischer, R.C.

    2003-01-01

    The Delmarva fox squirrel, Sciurus niger cinereus, is a federally listed endangered subspecies whose range has been reduced by 90%. In an attempt to increase both population size and range, translocation sites were established beginning in the 1960's by moving squirrels from the natural range to sites outside the current range. Although translocations have served as the primary component of the DFS recovery program, there has been very little post-release examination of the genetics of the translocation sites. In this study, we developed ten microsatellite loci, screened the three polymorphic loci, and sequenced a 330 bp fragment of the mitochondrial control region in order to assess levels of genetic variation in natural and translocated regions of Delmarva fox squirrels and to compare them to Southeastern fox squirrels (S. n. niger). Although we found low levels of microsatellite polymorphism, there were no differences in heterozygosity between natural and translocated regions, or between Delmarva and Southeastern fox squirrels. We found high levels of polymorphism in the mitochondrial control region. Our patterns of haplotype diversity suggest incomplete lineage sorting of the two subspecies. In general, our data suggest that the current levels of genetic variation in the translocated sites are representative of those found in the natural population, and we encourage the continued use of translocations as a major component of Delmarva fox squirrel recovery.

  13. Monitoring interactions between red-cockaded woodpeckers and southern flying squirrels.

    SciTech Connect

    Risch, Thomas S; Loeb, Susan C

    2004-12-31

    Risch, Thomas S., and Susan C. Loeb. 2004. Monitoring interactions between red-cockaded woodpeckers and southern flying squirrels. In: Red-cockaded woodpecker; Road to Recovery. Proceedings of the 4th Red-cockaded woodpecker Symposium. Ralph Costa and Susan J. Daniels, eds. Savannah, Georgia. January, 2003. Chapter 8. Cavities, Cavity Trees, and Cavity Communities. Pp 504-505. Abstract: Although several studies have suggested that southern flying squirrels (Glaucomys volans) may have a significant negative impact on red-cockades woodpeckers (Picoides borealsi) (Loeb and Hooper 1997, Laves and Loeb 1999), the nature of the interactions between the species remains unclear. Particularly lacking are data that address if southern flying squirrels directly usurp red-cockaded woodpecker s from cavities, or simply occupy cavities previously abandoned by red-cockaded woodpeckers. Ridley et al. (1997) observed the displacement of a red-cockaded woodpecker by a southern flying squirrel that was released after being captured. Observations of nocturnal displacements of red-cockaded woodpeckers by flying squirrels, however, are lacking. Due to the difficulty of observing interspecific interactions, determining the mechanisims by which flying squirrels impact red-cockaded woodpeckers is problematic.

  14. Acute toxoplasmosis in squirrel monkeys (Saimiri sciureus) in Mexico.

    PubMed

    Cedillo-Peláez, Carlos; Rico-Torres, Claudia Patricia; Salas-Garrido, Carlos Gerardo; Correa, Dolores

    2011-08-25

    Toxoplasma gondii causes fatal multisystemic disease in New World primates, with respiratory failure and multifocal necrotic lesions. Although cases and outbreaks of toxoplasmosis have been described, there are few genotyping studies and none has included parasite load quantification. In this article, we describe two cases of lethal acute toxoplasmosis in squirrel monkeys (Saimiri sciureus) of Mexico city. The main pathological findings included pulmonary edema, interstitial pneumonia, hepatitis and necrotizing lymphadenitis, and structures similar to T. gondii tachyzoites observed by histopathology in these organs. Diagnosis was confirmed by immunohistochemistry, transmission electron microscopy and both end point and real time PCR. The load was between <14 and 23 parasites/mg tissue. Digestion of the SAG3 gene amplicon showed similar bands to type I reference strains. These are the first cases of toxoplasmosis in primates studied in Mexico, with clinical features similar to others reported in Israel and French Guiana, although apparently caused by a different T. gondii variant.

  15. Motion sickness elicited by passive rotation in squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Daunton, Nancy G.; Fox, Robert A.

    1991-01-01

    Current theory and recent evidence suggest that motion sickness occurs under conditions of sensory input in which the normal motor programs for producing eye, head, and body movements are not functionally effective, i.e. under conditions in which there are difficulties in maintaining posture and controlling eye movements. Conditions involving conflicting or inconsistent visual-vestibular (VV) stimulation should thus result in greater sickness rates since the existing motor programs do not produce effective control of eye-head-body movements under such conditions. It is felt that the relationship of postural control to motion sickness is an important one and one often overlooked. The results are reported which showed that when postural requirements were minimized by fully restraining squirrel monkeys during hypogravity parabolic flight, no animals became motion sick, but over 80 percent of the same 11 animals became sick if they were unrestrained and maintained control of their posture.

  16. Outbreak of pasteurellosis in captive Bolivian squirrel monkeys (Saimiri boliviensis)

    PubMed Central

    YOSHINO, Mizuki; SASAKI, Jun; KURAMOCHI, Konomi; IKEZAWA, Mitsutaka; MUKAIZAWA, Natsuko; GORYO, Masanobu

    2017-01-01

    In September 2012, five Bolivian squirrel monkeys housed in a zoological park died within sequential several days without obvious clinical signs. In a necrospy, one monkey presented swelling of the kidney with multifocal white nodules in the parenchyma, and other two had pulmonary congestion. Histopathologically, multifocal bacterial colonies of gram-negative coccobacillus were found in the sinusoid of the liver in all monkeys examined (Nos.1−4). Additionally, purulent pyelonephritis, pneumonia and disseminated small bacterial colonies in blood vessels were observed. Immunohistochemically, the bacterial colonies from two monkeys were positive for P. multocida capsular serotype D. Based on these findings, these monkeys were diagnosed as septicemia caused by acute P. multocida infection. PMID:28190821

  17. Chemotherapy of haemobartonellosis in squirrel monkeys (Saimiri sciureus).

    PubMed

    Michel, J C; de Thoisy, B; Contamin, H

    2000-04-01

    Splenectomised Saimiri sciureus squirrel monkeys are being used increasingly as an experimental host for human malarial studies, notably for the assessment of candidate vaccines against Plasmodium falciparum blood-stage infection. Recently, we have reported that colony-reared S. sciureus monkeys are asymptomatic carriers of Haemobartonella sp. and that patent Haemobartonella infection, activated following splenectomy, may interfere with the course of P. falciparum parasitaemia in these animals. For several years, splenectomised S. sciureus monkeys were routinely submitted to oxytetracycline therapy before their use in malarial studies in order to prevent a possible spontaneous Heamobartonella infection. However, we report here that such antibiotic therapy is often ineffective and that neoarsphenamine chemotherapy may be considered as an alternative to cure both latent and patent haemobartonellosis in S. sciureus monkeys.

  18. Early adaptation to altered gravitational environments in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Fuller, C. A.

    1985-01-01

    The feeding behavior of two squirrel monkeys flown in Spacelab 3 is compared to that of six monkeys exposed to 1.5 G through centrifugation. The monkeys in the centrifugation study were housed unrestrained in cages, maintained at 25 C + or - 1 C, exposed to a 12:12 light/dark cycle, and had unrestrained access to food and water. The Spacelab monkeys were maintained at 26 C, exposed to a 12:12 light/dark cycle and had unlimited food and water. It is observed that the centrifuge rats displayed a change in feeding behavior for 4 days prior to resuming a normal pattern; one Spacelab monkey exhibited a 6 day depression before recover to control levels, and the feeding pattern of the second monkey was not influenced by the environment. It is noted that the effect of an altered dynamic environment is variable on the feeding behavior of individual monkeys.

  19. Vocalization-correlated respiratory movements in the squirrel monkey.

    PubMed

    Häusler, U

    2000-10-01

    Respiratory abdominal movements associated with vocalization were recorded in awake squirrel monkeys. Several call types, such as peeping, trilling, cackling, and err-chucks, were accompanied by large vocalization-correlated respiratory movements (VCRM) that started before vocalization. During purring, in contrast, only small VCRM were recorded that started later after vocal onset. VCRM during trill calls, a vocalization type with repetitive frequency modulation, showed a modulation in the rhythm of the frequency changes. A correlation with amplitude modulation was also present, but more variable. As high frequencies need a higher lung pressure for production than low frequencies, the modulation of VCRM seems to serve to optimize the lung pressure in relation to the vocalization frequency. The modulation, furthermore, may act as a mechanism to produce different trill variants. During err-chucks and staccato peeps, which show a large amplitude modulation, a nonmodulated VCRM occurred. This indicates the existence of a laryngeal amplitude-controlling mechanism that is independent from respiration.

  20. Acute physiological responses of squirrel monkeys exposed to hyperdynamic environments

    NASA Technical Reports Server (NTRS)

    Fuller, C. A.

    1984-01-01

    Physiological and behavioral responses to a hyperdynamic environment were examined in four adult male squirrel monkeys. After baseline monitoring at 1 G, monkeys were exposed to one of three conditions: (1) +2 Gz for 60 minutes, (2) +2.9 Gz max for 8 minutes (simulating Space Shuttle launch), or (3) +1.7 Gz max for 19 minutes (simulating Space Shuttle reentry). During all experimental conditions, heart rate rose, and colonic temperature began to decline within the first ten minutes of centrifugation and decreased by as much as 2 C in some instances. Behaviorally, during centrifugation, the monkeys seemed to exhibit drowsiness and fall asleep, an observation not made during the control period. It is concluded that primates are susceptible to acute hyperdynamic field exposure.

  1. Demography of northern flying squirrels informs ecosystem management of western interior forests.

    PubMed

    Lehmkuhl, John F; Kistler, Keith D; Begley, James S; Boulanger, John

    2006-04-01

    We studied northern flying squirrel (Glaucomys sabrinus) demography in the eastern Washington Cascade Range to test hypotheses about regional and local abundance patterns and to inform managers of the possible effects of fire and fuels management on flying squirrels. We quantified habitat characteristics and squirrel density, population trends, and demography in three typical forest cover types over a four-year period. We had 2034 captures of flying squirrels over 41 000 trap nights from 1997 through 2000 and marked 879 squirrels for mark-recapture population analysis. Ponderosa pine (Pinus ponderosa) forest appeared to be poorer habitat for flying squirrels than young or mature mixed-conifer forest. About 35% fewer individuals were captured in open pine forest than in dry mixed-conifer Douglas-fir (Pseudotsuga menziesii) and grand fir (Abies grandis) forests. Home ranges were 85% larger in pine forest (4.6 ha) than in mixed-conifer forests (2.5 ha). Similarly, population density (Huggins estimator) in ponderosa pine forest was half (1.1 squirrels/ha) that of mixed-conifer forest (2.2 squirrels/ha). Tree canopy cover was the single best correlate of squirrel density (r = 0.77), with an apparent threshold of 55% canopy cover separating stands with low- from high-density populations. Pradel estimates of annual recruitment were lower in open pine (0.28) than in young (0.35) and mature (0.37) forest. High recruitment was most strongly associated with high understory plant species richness and truffle biomass. Annual survival rates ranged from 45% to 59% and did not vary among cover types. Survival was most strongly associated with understory species richness and forage lichen biomass. Maximum snow depth had a strong negative effect on survival. Rate of per capita increase showed a density-dependent response. Thinning and prescribed burning in ponderosa pine and dry mixed conifer forests to restore stable fire regimes and forest structure might reduce flying squirrel

  2. Differential Estimates of Southern Flying Squirrel (Glaucomys volans) Population Structure Based on Capture Method.

    SciTech Connect

    Laves, Kevin S.; Loeb, Susan C.

    2006-01-01

    ABSTRACT.—It is commonly assumed that population estimates derived from trapping small mammals are accurate and unbiased or that estimates derived from different capture methods are comparable. We captured southern flying squirrels (Glaucomys volans) using two methods to study their effect on red-cockaded woodpecker (Picoides borealis) reproductive success. Southern flying squirrels were captured at and removed from 30 red-cockaded woodpecker cluster sites during March to July 1994 and 1995 using Sherman traps placed in a grid encompassing a red-cockaded woodpecker nest tree and by hand from red-cockaded woodpecker cavities. Totals of 195 (1994) and 190 (1995) red-cockaded woodpecker cavities were examined at least three times each year. Trappability of southern flying squirrels in Sherman traps was significantly greater in 1995 (1.18%; 22,384 trap nights) than in 1994 (0.42%; 20,384 trap nights), and capture rate of southern flying squirrels in cavities was significantly greater in 1994 (22.7%; 502 cavity inspections) than in 1995 (10.8%; 555 cavity inspections). However, more southern flying squirrels were captured per cavity inspection than per Sherman trap night in both years. Male southern flying squirrels were more likely to be captured from cavities than in Sherman traps in 1994, but not in 1995. Both male and female juveniles were more likely to be captured in cavities than in traps in both years. In 1994 males in reproductive condition were more likely to be captured in cavities than in traps and in 1995 we captured significantly more reproductive females in cavities than in traps. Our data suggest that population estimates based solely on one trapping method may not represent true population size or structure of southern flying squirrels.

  3. Differential estimates of southern flying squirrel (Glaucomys volans) population structure based on capture method

    USGS Publications Warehouse

    Laves, K.S.; Loeb, S.C.

    2006-01-01

    It is commonly assumed that population estimates derived from trapping small mammals are accurate and unbiased or that estimates derived from different capture methods are comparable. We captured southern flying squirrels (Glaucomys volans) using two methods to study their effect on red-cockaded woodpecker (Picoides borealis) reproductive success. Southern flying squirrels were captured at and removed from 30 red-cockaded woodpecker cluster sites during March to July 1994 and 1995 using Sherman traps placed in a grid encompassing a red-cockaded woodpecker nest tree and by hand from red-cockaded woodpecker cavities. Totals of 195 (1994) and 190 (1995) red-cockaded woodpecker cavities were examined at least three times each year. Trappability of southern flying squirrels in Sherman traps was significantly greater in 1995 (1.18%; 22,384 trap nights) than in 1994 (0.42%; 20,384 trap nights), and capture rate of southern flying squirrels in cavities was significantly greater in 1994 (22.7%; 502 cavity inspections) than in 1995 (10.8%; 555 cavity inspections). However, more southern flying squirrels were captured per cavity inspection than per Sherman trap night in both years. Male southern flying squirrels were more likely to be captured from cavities than in Sherman traps in 1994, but not in 1995. Both male and female juveniles were more likely to be captured in cavities than in traps in both years. In 1994 males in reproductive condition were more likely to be captured in cavities than in traps and in 1995 we captured significantly more reproductive females in cavities than in traps. Our data suggest that population estimates based solely on one trapping method may not represent true population size or structure of southern flying squirrels.

  4. Experimental infection of ectoparasitic arthropods with Rickettsia prowazekii (GvF-16 strain) and transmission to flying squirrels.

    PubMed

    Bozeman, F M; Sonenshine, D E; Williams, M S; Chadwick, D P; Lauer, D M; Elisberg, B L

    1981-01-01

    Epizootiologic studies conducted during the past few years showed the existence of widespread natural infection of the southern flying squirrel, Glaucomys volans, with epidemic typhus rickettsiae, Rickettsia prowazekii. The ecological findings strongly implicated transmission of the etiologic agent by an arthropod vector. Studies were conducted under controlled laboratory conditions to determine whether ectoparasites naturally associated with flying squirrels (squirrel fleas, lice, mites and ticks) were capable of acquiring, maintaining and transmitting the infection. Also studied were the cat flea, oriental rat flea and the human body louse. Flying squirrels inoculated with the GvF-16 strain of R. prowazekii circulated rickettsiae in their blood for 2-3 weeks, thus providing ample opportunity for arthropods feeding on them to become infected. The results with Dermacentor variabilis ticks indicated that the rickettsiae did not consistently survive in this insect and were not passed to the eggs of adult females that had been infected subcuticularly. Mites became infected by feeding on infectious blood but failed to sustain the infection. Also, mites fed on an infected flying squirrel did not transmit the infection to a normal squirrel. Squirrel, cat, and oriental rat fleas readily became infected by feeding on a rickettsemic host or on infectious blood through membranes, but failed to transmit the infection to susceptible flying squirrels. In the studies with flying squirrel lice, however, transmission of epidemic typhus from infected to uninfected flying squirrels was demonstrated. Infection of the human body louse with the GvF-16 flying squirrel strain of R. prowazekii was similar to that previously observed with classical human strains, viz., multiplication of the rickettsiae and excretion in the feces.

  5. New data about the helminth fauna of the red squirrel (Sciurus vulgaris Linnaeus, 1758) in Belorussian Polesie.

    PubMed

    Shimalov, V V

    2016-12-01

    The result of helminthological examination of 5 red squirrels in Belorussian Polesie during 2003-2012 is presented. Two species of helminths were found: Taenia martis (Zeder, 1803) larvae and Syphacia thompsoni Price, 1928. The red squirrel for the first time established as host of cestode T. martis. The nematode S. thompsoni registered as Syphacia sp. in this region between 1985 and 2000.

  6. Using GPS telemetry to validate least-cost modeling of gray squirrel (Sciurus carolinensis) movement within a fragmented landscape

    PubMed Central

    Stevenson, Claire D; Ferryman, Mark; Nevin, Owen T; Ramsey, Andrew D; Bailey, Sallie; Watts, Kevin

    2013-01-01

    In Britain, the population of native red squirrels Sciurus vulgaris has suffered population declines and local extinctions. Interspecific resource competition and disease spread by the invasive gray squirrel Sciurus carolinensis are the main factors behind the decline. Gray squirrels have adapted to the British landscape so efficiently that they are widely distributed. Knowledge on how gray squirrels are using the landscape matrix and being able to predict their movements will aid management. This study is the first to use global positioning system (GPS) collars on wild gray squirrels to accurately record movements and land cover use within the landscape matrix. This data were used to validate Geographical Information System (GIS) least-cost model predictions of movements and provided much needed information on gray squirrel movement pathways and network use. Buffered least-cost paths and least-cost corridors provide predictions of the most probable movements through the landscape and are seen to perform better than the more expansive least-cost networks which include all possible movements. Applying the knowledge and methodologies gained to current gray squirrel expansion areas, such as Scotland and in Italy, will aid in the prediction of potential movement areas and therefore management of the invasive gray squirrel. The methodologies presented in this study could potentially be used in any landscape and on numerous species. PMID:23919175

  7. Flying squirrel-associated Rickettsia prowazekii (epidemic typhus rickettsiae) characterized by a specific DNA fragment produced by restriction endonuclease digestion.

    PubMed Central

    Regnery, R L; Fu, Z Y; Spruill, C L

    1986-01-01

    The DNA from flying squirrel-associated Rickettsia prowazekii was characterized by using a specific DNA fragment produced by digestion with the enzyme BamHI. The DNA fragment was cloned into a plasmid vector and used to readily distinguish between available human- and flying squirrel-associated R. prowazekii DNAs derived from crude cytoplasmic extracts. Images PMID:3009528

  8. Rock squirrel (Spermophilus variegatus) blood sera affects proteolytic and hemolytic activities of rattlesnake venoms.

    PubMed

    Biardi, James E; Coss, Richard G

    2011-02-01

    Rock squirrels (Spermophilus variegatus) from two sites in south central New Mexico, where prairie (Crotalus viridis viridis) and western diamondback (Crotalus atrox) rattlesnakes are common predators, were assayed for inhibition of rattlesnake venom digestive and hemostatic activities. At statistically significant levels rock squirrel blood sera reduced the metalloprotease and hemolytic activity of venoms from C. v. viridis and C. atrox more than venom from an allopatric snake species, the northern Pacific rattlesnake (Crotalus oreganus). In contrast, general proteolytic activity of venom from C. oreganus was inhibited more by S. variegatus serum defenses than activity of venom from sympatric snakes. For all three venoms, incubation with squirrel sera increased the level of fibrinolysis over venom-only treatments. These results suggest that rock squirrels (S. variegatus) can defend against metalloproteases and other proteases after envenomation from at least two of five rattlesnake predators they might encounter. However, there were statistically significant differences between general proteolytic activity and fibrinolytic activity of C. v. viridis and C. atrox venom, suggesting that rock squirrels might be differentially vulnerable to these two predators. The hypothesis that prey resistance influences snake venom evolution in a predator-prey arms race is given further support by the previously cryptic variation in venoms detected when assayed against prey defenses.

  9. Mapping and Monitoring Delmarva Fox Squirrel Habitat Using an Airborne LiDAR Profiler

    NASA Technical Reports Server (NTRS)

    Nelson, Ross; Ratnaswamy, Mary; Keller, Cherry

    2004-01-01

    Twenty five hundred thirty nine kilometers of airborne laser profiling and videography data were acquired over the state of Delaware during the summer of 2000. The laser ranging measurements and video from approximately one-half of that data set (1304 km) were analyzed to identify and locate forested sites that might potentially support populations of Delmarva fox squirrel (DFS, Sciurus niger cinereus). The DFS is an endangered species previously endemic to tall, dense, mature forests with open understories on the Eastern Shore of the Chesapeake Bay. The airborne LiDAR employed in this study can measure forest canopy height and canopy closure, but cannot measure or infer understory canopy conditions. Hence the LiDAR must be viewed as a tool to map potential, not actual, habitat. Fifty-three potentially suitable DFS sites were identified in the 1304 km of flight transect data. Each of the 53 sites met the following criteria according to the LiDAR and video record: (1 ) at least 120m of contiguous forest; (2) an average canopy height greater than 20m; (3) an average canopy closure of >80%; and (4) no roofs, impervious surface (e.g., asphalt, concrete), and/or open water anywhere along the 120m length of the laser segment. Thirty-two of the 53 sites were visited on the ground and measurements taken for a DFS habitat suitability model. Seventy eight percent of the sites (25 of 32) were judged by the model to be suited to supporting a DFS population. Twenty-eight of the 32 sites visited in the field were in forest cover types (hardwood, mixed wood, conifer, wetlands) according to a land cover GIS map. Of these, 23 (82%) were suited to support DFS. The remaining 4 sites were located in nonforest cover types - agricultural or residential areas. Two of the four, or 50% were suited to the DFS. All of the LiDAR flight data, 2539 km, were analyzed to

  10. Larva migrans in squirrel monkeys experimentally infected with Baylisascaris potosis.

    PubMed

    Tokiwa, Toshihiro; Tsugo, Kosuke; Nakamura, Shohei; Taira, Kensuke; Une, Yumi

    2015-10-01

    Roundworms of the genus Baylisascaris are natural parasites primarily of wild carnivores, and they can occasionally cause infection in humans and animals. Infection results in visceral larva migrans and/or neural larva migrans, which can be severe or fatal in some animals. Recently, Baylisascaris nematodes isolated from kinkajous (Potos flavus) and previously referred to as Baylisascaris procyonis were renamed as Baylisascaris potosis; however, data regarding the pathogenicity of B. potosis towards animals and humans are lacking. In the present study, we experimentally infected squirrel monkeys (Saimiri sciureus) with B. potosis to determine the suitability of the monkey as a primate model. We used embryonated eggs of B. potosis at two different doses (10,000 eggs and 100,000 eggs) and examined the animals at 30 days post-infection. Histopathological examination showed the presence of B. potosis larvae and infiltration of inflammatory cells around a central B. potosis larvae in the brain, intestines, and liver. Nevertheless, the monkeys showed no clinical signs associated with infection. Parasitological examination revealed the presence of B. potosis larvae in the intestines, liver, lung, muscles, brain, kidney, and diaphragm. Our findings extend the range of species that are susceptible to B. potosis and provide evidence for the zoonotic potential of larva migrans in high dose infections.

  11. Evaluation of neonatal squirrel monkeys receiving tritiated water throughout gestation

    SciTech Connect

    Jones, D.C.L.; Krebs, J.S.; Sasmore, D.P.; Mitoma, C.

    1980-09-01

    Pregnant squirrel monkeys received tritiated water (HTO) in the drinking water throughout gestation at levels ranging from 16 to 1000 times the permissible level for human consumption (0.003 ..mu..Ci/ml), resulting in mean body water HTO levels ranging from 0.05 to 3.1 ..mu..Ci/ml. There were no discernible effects of HTO administration on the newborn progeny in terms of body weight, body dimensions, selected organ weights (brain, heart, adrenal, kidney, liver, spleen), hematologic patterns, and histology of selected organs and tissues (adrenal, kidney, liver, lung, brain, pancreas, jejunum, pituitary, spleen, testes, thymus, skin) other than ovaries. The number of primary oocytes in female progeny decreased markedly with increasing levels of HTO in maternal drinking water. Quantitative analysis of neonate ovaries, testes, brain tissue, and retinal tissue is in progress. No effects of HTO administration on maternal body weight, gestation time, or maintenance of pregnancy to full term were observed. Body weights of HTO-treated inseminated females that did not deliver were less than control weights, but the lack of dose dependence implies that this effect may have been associated with a stimulus characteristic of the HTO administration rather than with irradiation.

  12. Three dimensional eye movements of squirrel monkeys following postrotatory tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Young, L. R.; Paige, G. D.; Tomko, D. L.

    1993-01-01

    Three-dimensional squirrel monkey eye movements were recorded during and immediately following rotation around an earth-vertical yaw axis (160 degrees/s steady state, 100 degrees/s2 acceleration and deceleration). To study interactions between the horizontal angular vestibulo-ocular reflex (VOR) and head orientation, postrotatory VOR alignment was changed relative to gravity by tilting the head out of the horizontal plane (pitch or roll tilt between 15 degrees and 90 degrees) immediately after cessation of motion. Results showed that in addition to post rotatory horizontal nystagmus, vertical nystagmus followed tilts to the left or right (roll), and torsional nystagmus followed forward or backward (pitch) tilts. When the time course and spatial orientation of eye velocity were considered in three dimensions, the axis of eye rotation always shifted toward alignment with gravity, and the postrotatory horizontal VOR decay was accelerated by the tilts. These phenomena may reflect a neural process that resolves the sensory conflict induced by this postrotatory tilt paradigm.

  13. Endogenous thermoregulatory rhythms of squirrel monkeys in thermoneutrality and cold

    NASA Technical Reports Server (NTRS)

    Robinson, E. L.; Fuller, C. A.

    1999-01-01

    Whole body heat production (HP) and heat loss (HL) were examined to determine if the free-running circadian rhythm in body temperature (Tb) results from coordinated changes in HP and HL rhythms in thermoneutrality (27 degrees C) as well as mild cold (17 degrees C). Squirrel monkey metabolism (n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of Tb and activity. Feeding was also measured. Rhythms of HP, HL, and conductance were tightly coupled with the circadian Tb rhythm at both ambient temperatures (TA). At 17 degrees C, increased HP compensated for higher HL at all phases of the Tb rhythm, resulting in only minor changes to Tb. Parallel compensatory changes of HP and HL were seen at all rhythm phases at both TA. Similar time courses of Tb, HP, and HL in their respective rhythms and the relative stability of Tb during both active and rest periods suggest action of the circadian timing system on Tb set point.

  14. The geographic selection mosaic for squirrels, crossbills and Aleppo pine.

    PubMed

    Mezquida, E T; Benkman, C W

    2005-03-01

    The interactions between many species are structured in a geographic mosaic of populations among which selection is divergent. Here we tested the hypothesis that such a geographic selection mosaic arises for common crossbills (Loxia curvirostra) feeding on seeds in the cones of Aleppo pine (Pinus halepensis) because of geographic variation in the occurrence of European red squirrels (Sciurus vulgaris). On the Iberian Peninsula, Sciurus exerted directional selection favouring larger cones with larger scales, which has caused cones there to be larger than in the Balearic Islands where Sciurus are absent. Moreover, cones on the Iberian Peninsula are so large that they are apparently little used by the relatively small-billed crossbills on the Peninsula; selection by Sciurus seems to have made the cones so difficult to feed on that crossbills rely mostly on the seeds of other conifers. Where crossbills are present but Sciurus are absent (Mallorca Island), cones were smaller as a result of relaxation of selection by Sciurus. However, cones on Mallorca had proportionally thicker scales in comparison to where both Sciurus and crossbills are absent (Ibiza Island), presumably as an adaptation against crossbill predation. Here crossbills specialize on Aleppo pine, have relatively large bills and have apparently coevolved in an arms race with Aleppo pine. These results suggest that Sciurus has influenced both the geographic selection mosaics for crossbills and conifers and the adaptive radiation of crossbills in Eurasia much like Tamiasciurus has done in the North America.

  15. Multiple introductions of the eastern fox squirrel (Sciurus niger) in California.

    PubMed

    Claytor, Sieara C; Muchlinski, Alan E; Torres, Elizabeth

    2015-08-01

    Eastern fox squirrels (Sciurus niger) have been introduced into California within the past 130 years. Recently, their range has been expanding at an alarming rate. Genetic diversity was assessed in 101 control region sequences of eastern fox squirrels from three geographic regions within California (Los Angeles County, Alameda and Contra Costa counties and Sacramento County) to determine if a single or multiple introductions occurred within California, as indicated by the detection of multiple haplotypes. A total of 11 haplotypes were discovered, with haplotypes rarely shared among geographic regions and no clustering by region in a haplotype network. This suggests that the introduction to different regions within California came from different source populations within the native range of the species. Haplotype diversity was highest in Los Angeles County. Due to a lack of phylogeographic structure in fox squirrels in their native range, it is difficult to identify the sources of all introductions.

  16. A brain MRI atlas of the common squirrel monkey, Saimiri sciureus

    NASA Astrophysics Data System (ADS)

    Gao, Yurui; Schilling, Kurt G.; Khare, Shweta P.; Panda, Swetasudha; Choe, Ann S.; Stepniewska, Iwona; Li, Xia; Ding, Zhoahua; Anderson, Adam; Landman, Bennett A.

    2014-03-01

    The common squirrel monkey, Saimiri sciureus, is a New World monkey with functional and microstructural organization of central nervous system similar to that of humans. It is one of the most commonly used South American primates in biomedical research. Unlike its Old World macaque cousins, no digital atlases have described the organization of the squirrel monkey brain. Here, we present a multi-modal magnetic resonance imaging (MRI) atlas constructed from the brain of an adult female squirrel monkey. In vivo MRI acquisitions include high resolution T2 structural imaging and low resolution diffusion tensor imaging. Ex vivo MRI acquisitions include high resolution T2 structural imaging and high resolution diffusion tensor imaging. Cortical regions were manually annotated on the co-registered volumes based on published histological sections.

  17. A brain MRI atlas of the common squirrel monkey, Saimiri sciureus.

    PubMed

    Gao, Yurui; Khare, Shweta P; Panda, Swetasudha; Choe, Ann S; Stepniewska, Iwona; Li, Xia; Ding, Zhoahua; Anderson, Adam; Landman, Bennett A

    2014-03-13

    The common squirrel monkey, Saimiri sciureus, is a New World monkey with functional and microstructural organization of central nervous system similar to that of humans. It is one of the most commonly used South American primates in biomedical research. Unlike its Old World macaque cousins, no digital atlases have described the organization of the squirrel monkey brain. Here, we present a multi-modal magnetic resonance imaging (MRI) atlas constructed from the brain of an adult female squirrel monkey. In vivo MRI acquisitions include T2 structural imaging and diffusion tensor imaging. Ex vivo MRI acquisitions include T2 structural imaging and diffusion tensor imaging. Cortical regions were manually annotated on the co-registered volumes based on published histological sections.

  18. Cluster of Sylvatic Epidemic Typhus Cases Associated with Flying Squirrels, 2004–2006

    PubMed Central

    Chapman, Alice S.; Swerdlow, David L.; Dato, Virginia M.; Anderson, Alicia D.; Moodie, Claire E.; Marriott, Chandra; Amman, Brian; Hennessey, Morgan; Fox, Perry; Green, Douglas B.; Pegg, Eric; Nicholson, William L.; Eremeeva, Marina E.

    2009-01-01

    In February 2006, a diagnosis of sylvatic epidemic typhus in a counselor at a wilderness camp in Pennsylvania prompted a retrospective investigation. From January 2004 through January 2006, 3 more cases were identified. All had been counselors at the camp and had experienced febrile illness with myalgia, chills, and sweats; 2 had been hospitalized. All patients had slept in the same cabin and reported having seen and heard flying squirrels inside the wall adjacent to their bed. Serum from each patient had evidence of infection with Rickettsia prowazekii. Analysis of blood and tissue from 14 southern flying squirrels trapped in the woodlands around the cabin indicated that 71% were infected with R. prowazekii. Education and control measures to exclude flying squirrels from housing are essential to reduce the likelihood of sylvatic epidemic typhus. PMID:19624912

  19. [Feeding habits of the squirrel Sciurus variegatoides (Rodentia: Sciuridae) in the Nicoya Peninsula, Costa Rica].

    PubMed

    Monge, Javier; Hilje, Luko

    2006-06-01

    Food items consumed by the squirrel Sciurus variegatoides atrirufus were determined in an agricultural setting in the Nicoya Peninsula (9 degrees 47' N, 84 degrees 56' W), Costa Rica, where two life zones (Premontane Moist Forest Basal Belt Transition, and Tropical Dry Forest) predominate. By analyzing the gut contents of 120 squirrels, from February 1987 through January 1988, it was determined that coconut (Cocos nucifera), indian almond (Terminalia catappa) and flamboyant (Delonix regia) were the most common dietary items. There were differences in food consumption according to age: adults preferred coconut, whereas young individuals preferred almond. This finding can be explained in terms of fruit characteristics, as well as tree architecture and accessibility for squirrels; almendro trees provide higher protection and a more accessible food resource, so that it was better used by young individuals.

  20. Macroparasite community of the Eurasian red squirrel (Sciurus vulgaris): poor species richness and diversity.

    PubMed

    Romeo, Claudia; Pisanu, Benoît; Ferrari, Nicola; Basset, Franck; Tillon, Laurent; Wauters, Lucas A; Martinoli, Adriano; Saino, Nicola; Chapuis, Jean-Louis

    2013-10-01

    The Eurasian red squirrel (Sciurus vulgaris) is the only naturally occurring tree squirrel throughout its range. We aim at improving current knowledge on its macroparasite fauna, expecting that it will have a poor parasite diversity because in species that have no sympatric congeners parasite richness should be lower than in hosts sharing their range with several closely related species, where host-switching events and lateral transmission are promoted. We examined gastro-intestinal helminth and ectoparasite communities (excluding mites) of, respectively, 147 and 311 red squirrel roadkills collected in four biogeographic regions in Italy and France. As expected, the macroparasite fauna was poor: we found five species of nematodes and some unidentified cestodes, three fleas, two sucking lice and two hard ticks. The helminth community was dominated by a single species, the oxyurid Trypanoxyuris (Rodentoxyuris) sciuri (prevalence, 87%; mean abundance, 373 ± 65 worms/host). Its abundance varied among seasons and biogeographic regions and increased with body mass in male hosts while decreased in females. The most prevalent ectoparasites were the flea Ceratophyllus (Monopsyllus) sciurorum (28%), whose presence was affected by season, and the generalist tick Ixodes (Ixodes) ricinus that was found only in France (34%). All the other helminths and arthropod species were rare, with prevalence below 10%. However, the first record of Strongyloides robustus, a common nematode of North American Eastern grey squirrels (S. carolinensis), in two red squirrels living in areas where this alien species co-inhabits, deserves further attention, since low parasite richness could result in native red squirrels being particularly vulnerable to parasite spillover.

  1. Touch screen assays of behavioural flexibility and error characteristics in Eastern grey squirrels (Sciurus carolinensis).

    PubMed

    Chow, Pizza Ka Yee; Leaver, Lisa A; Wang, Ming; Lea, Stephen E G

    2017-01-27

    Behavioural flexibility allows animals to adjust their behaviours according to changing environmental demands. Such flexibility is frequently assessed by the discrimination-reversal learning task. We examined grey squirrels' behavioural flexibility, using a simultaneous colour discrimination-reversal learning task on a touch screen. Squirrels were trained to select their non-preferred colour in the discrimination phase, and their preferred colour was rewarded in a subsequent reversal phase. We used error rates to divide learning in each phase into three stages (perseveration, chance level and 'learned') and examined response inhibition and head-switching during each stage. We found consistent behavioural patterns were associated with each learning stage: in the perseveration stage, at the beginning of each training phase, squirrels showed comparable response latencies to correct and incorrect stimuli, along with a low level of head-switching. They quickly overcame perseveration, typically in one to three training blocks. In the chance-level stage, response latencies to both stimuli were low, but during initial discrimination squirrels showed more head-switches than in the previous stage. This suggests that squirrels were learning the current reward contingency by responding rapidly to a stimulus, but with increased attention to both stimuli. In the learned stage, response latencies to the correct stimulus and the number of head-switches were at their highest, whereas incorrect response latencies were at their lowest, and differed significantly from correct response latencies. These results suggest increased response inhibition and attention allowed the squirrels to minimise errors. They also suggest that errors in the 'learned' stage were related to impulsive emission of the pre-potent or previously learned responses.

  2. Melanocortin 1 receptor (MC1R) gene sequence variation and melanism in the gray (Sciurus carolinensis), fox (Sciurus niger), and red (Sciurus vulgaris) squirrel.

    PubMed

    McRobie, Helen R; King, Linda M; Fanutti, Cristina; Coussons, Peter J; Moncrief, Nancy D; Thomas, Alison P M

    2014-01-01

    Sequence variations in the melanocortin 1 receptor (MC1R) gene are associated with melanism in many different species of mammals, birds, and reptiles. The gray squirrel (Sciurus carolinensis), found in the British Isles, was introduced from North America in the late 19th century. Melanism in the British gray squirrel is associated with a 24-bp deletion in the MC1R. To investigate the origin of this mutation, we sequenced the MC1R of 95 individuals including 44 melanic gray squirrels from both the British Isles and North America. Melanic gray squirrels of both populations had the same 24-bp deletion associated with melanism. Given the significant deletion associated with melanism in the gray squirrel, we sequenced the MC1R of both wild-type and melanic fox squirrels (Sciurus niger) (9 individuals) and red squirrels (Sciurus vulgaris) (39 individuals). Unlike the gray squirrel, no association between sequence variation in the MC1R and melanism was found in these 2 species. We conclude that the melanic gray squirrel found in the British Isles originated from one or more introductions of melanic gray squirrels from North America. We also conclude that variations in the MC1R are not associated with melanism in the fox and red squirrels.

  3. Spatial organization of northern flying squirrels, Glaucomys sabrinus: Territoriality in females?

    USGS Publications Warehouse

    Smith, J.R.; Vuren, D.H.V.; Kelt, D.A.; Johnson, M.L.

    2011-01-01

    We determined home-range overlap among northern flying squirrels (Glaucomys sabrinus) to assess their spatial organization. We found extensive home-range overlap among females, and though this overlap could reflect social behavior, we found no evidence of attraction among females, with only one instance of den sharing. Instead, our results suggest that females share foraging areas but may be territorial in portions of the home range, especially around den trees and during young-rearing. Home-range overlap could also result from, the extrinsic effect of forest fragmentation due to timber harvest, which might impede dispersal and force squirrels to cluster on remaining fragments of suitable habitat.

  4. Projections from the 'cingular' vocalization area in the squirrel monkey.

    PubMed

    Müller-Preuss, P; Jürgens, U

    1976-02-13

    In 5 squirrel monkeys the anatomical projections from the 'cingular' vocalization area were studied by the autoradiographic tracing technique. The 'cingular' vocalization area lies around the sulcus cinguli at the level of the genu of the corpus callosum; its electrical stimulation yields purring and cackling calls. The following efferent connections were found: corticocortical fibers could be traced into the orbital cortex (areas 10 and 11), dorsomedial frontal cortex (areas 9, 8 and 6), limbic cortex (areas 25, 24 and 23), Broca's area (area 44), frontal operculum (area 50), insula (areas 13 and 14), and auditory association cortex (area 22). Subcortical terminal fields within the telencephalon were found in the nucleus caudatus, putamen, claustrum, globus pallidus, olfactory tubercle, preoptic region and nucleus centralis and basolateralis amygdalae. Fibers reached most of these structures along different trajectories. In the diencephalon terminal fields lay in the dorsal hypothalamus, the subthalamus, lateral habenular nucleus, and the following thalamic nuclei: nucleus reticularis, ventralis anterior, centralis medialis, centralis superior lateralis, centralis inferior, submedius, medialis dorsalis and centrum medianum. In the midbrain, the periaqueductal gray was the only projection area, extending into the parabrachial nuclei at the pontomesencephalic transition. The most caudal terminal field was found in the medial pontine gray. No terminals were detected in the nucleus ambiguus, nucleus n. hypoglossi or in any other cranial motor nucleus involved in phonation processes. A comparison of this projection system with the whole of structures producing vocalization when electrically stimulated yielded only partial overlap. Not all vocalization areas lie within the 'cingular' projection system, and inversely, not the whole projection system yielded vocalization. Overlap took place in the anterior limbic cortex, preoptic region, central amygdaloid nucleus

  5. Increased Production of 11β-hydroxysteroid Dehydrogenase Type 2 in the Kidney Microsomes of Squirrel Monkeys (Saimiri spp.)

    PubMed Central

    Sadosky, Patti W; Scammell, Jonathan G

    2008-01-01

    In squirrel monkeys (Saimiri spp.), cortisol circulates at levels much higher than those seen in man and other Old World primates, but squirrel monkeys exhibit no physiologic signs of the mineralocorticoid effects of cortisol. These observations suggest that squirrel monkeys have mechanisms for protection of the mineralocorticoid receptor (MR) from these high levels of cortisol. We previously showed that the serum cortisol to cortisone ratio in these animals is low relative to that in human serum, suggesting that production of the MR protective enzyme, 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), is increased in squirrel monkeys. Here, we directly evaluate whether increased production of 11β-HSD2, which inactivates cortisol to cortisone, is a mechanism for protection of MR. In vitro assays showed that 11β-HSD2 activity in squirrel monkey kidney microsomes was 3 to 7 times higher than that seen in kidney microsomes from pig or rabbit. 11β-HSD2 protein detected by Western blot analysis was 4 to 9 times greater in squirrel monkey microsomes than in pig or rabbit microsomes. Comparison of the effect of expression of either human or squirrel monkey 11β-HSD2 on MR transactivation activity showed similar inhibition of MR response to cortisol by both enzymes, indicating that the intrinsic activities of the human and squirrel monkey enzymes are similar. These findings suggest that one mechanism by which squirrel monkeys protect the MR from activation by high cortisol levels in the kidney is by upregulation of 11β-HSD2 activity through increased production of the enzyme. PMID:18524177

  6. Influence of thinning of Douglas-fir forests on population parameters and diet of northern flying squirrels

    USGS Publications Warehouse

    Gomez, D.M.; Anthony, R.G.; Hayes, J.P.

    2005-01-01

    We investigated the effects of thinning young (35- to 45-yr-old) Douglas-fir (Pseudotsuga menziesii) forests on density, survival, body mass, movements, and diets of northern flying squirrels (Glaucomys sabrinus) in the northern coast range of Oregon. We used a repeated measures, randomized block design with 3 treatments (control, moderate thinning, and heavy thinning) and 4 replicates to study diets and population characteristics from 1994-1997. Densities of flying squirrels were variable in space and time, but they were positively correlated to biomass and frequency of fungal sporocarps, suggesting they were responding to food resources rather than forest structure. Fungal sporocarps comprised a major portion of the squirrel's diet, and other vegetative material made up the remainder of the diet. Several fungal genera including Gautieria, Geopora, Hymenogaster, Hysterangium, Melanogaster, and Rhizopogon were found more frequently in diets than on the trapping grids and therefore appeared to be selected by the squirrels. Flying squirrel movements were negatively correlated with the frequency of occurrence of fungal sporocarps at trap stations, suggesting that squirrels traveled greater distances to find fungal sporocarps where these food items were more sparsely distributed. We hypothesized that flying squirrel densities would be relatively low in these young, structurally simple forests; however, densities on some of the grids were >1.5 squirrels/ha, which was comparable to densities described for the species in late-successional forests. Our results indicated that commercial thinning did not have measurable short-term effects on density, survival, or body mass of flying squirrels.

  7. Causes of mortality and pathological lesions observed post-mortem in red squirrels (Sciurus vulgaris) in Great Britain

    PubMed Central

    2013-01-01

    Background The red squirrel population in Great Britain has declined dramatically in recent decades, principally due to squirrelpox. Concern exists that red squirrels may become extinct nationally and, as there has been limited research in to diseases other than squirrelpox, this study aimed to identify additional causes of mortality. Results Post-mortem examinations on 163 red squirrels found dead on Isle of Wight (IoW) England, in Scotland and at other locations in Great Britain showed that 41.7% (n = 68) were killed by road traffic and 9.2% (n = 15) by predators, principally domestic cats and dogs. The overall male/female ratio was 1.08/1. Fleas were recorded on 34.9% of IoW squirrels and on 43.8% of Scottish squirrels but sucking lice and ixodid ticks were only seen on Scottish squirrels. Bacterial infections were significant, particularly in association with respiratory disease (n = 16); two squirrels died of Bordetella bronchiseptica bronchopneumonia. Cases of fatal exudative dermatitis (n = 5) associated with a lukM-positive clone of Staphylococcus aureus occurred only on the IoW. Toxoplasmosis (n = 12) was also confined to IoW where it was responsible for almost one tenth (9.5%) of all deaths. Hepatozoonosis was common, especially in IoW squirrels, but was not considered a primary cause of mortality. Hepatic capillariasis affected four IoW squirrels and one from Scotland. Fungal infections included oral candidiasis, adiaspiromycosis and pulmonary phaeohyphomycosis. Neoplastic conditions diagnosed were: pulmonary carcinoma, gastric spindle cell tumour, renal papillary adenoma and trichoepithelioma. Epidermal hyperplasia of unknown aetiology was seen in squirrels showing crusty lesions of the ear pinnae on IoW (n = 3) and Brownsea Island (n = 1), associated in two cases with cutaneous wart-like growths. Miscellaneous diagnoses included chylothorax, electrocution, intussusception, suspected cholecalciferol rodenticide poisoning and

  8. Echocardiographic and Electrocardiographic Characteristics of Male and Female Squirrel Monkeys (Saimiri spp.)

    PubMed Central

    Huss, Monika K; Ikeno, Fumiaki; Buckmaster, Christine L; Albertelli, Megan A

    2015-01-01

    Cardiomyopathy is a leading cause of mortality in aging squirrel monkeys (Saimiri spp.). However, data regarding echocardiographic measures obtained from clinically healthy nonsedated squirrel monkeys have not been published, and few electrocardiographic data are available. Here we obtained echocardiographs without sedation and electrocardiographs with minimal sedation from 63 clinically healthy squirrel monkeys that ranged from 3 to 20 y in age. 2D and M-mode echocardiography were performed on nonsedated monkeys to determine the left ventricular internal diameters at systole and diastole and the ejection fraction. Electrocardiography was performed under sedation with ketamine (15 mg/kg). Parameters evaluated included heart rate; P-wave duration; lengths of the PR, QRS, and QT intervals; R-wave amplitude, and P-wave amplitude. Initial physical examination, electrocardiography, and echocardiography indicated normal cardiac function for all monkeys. The objectives of this study were to provide reference values for nonsedated echocardiography and ketamine-sedated electrocardiography of clinically normal squirrel monkeys and to determine correlates of age and sex in these values. PMID:25651087

  9. Acorn Caching in Tree Squirrels: Teaching Hypothesis Testing in the Park

    ERIC Educational Resources Information Center

    McEuen, Amy B.; Steele, Michael A.

    2012-01-01

    We developed an exercise for a university-level ecology class that teaches hypothesis testing by examining acorn preferences and caching behavior of tree squirrels (Sciurus spp.). This exercise is easily modified to teach concepts of behavioral ecology for earlier grades, particularly high school, and provides students with a theoretical basis for…

  10. Responses of squirrel monkeys to seasonal changes in food availability in an eastern Amazonian forest.

    PubMed

    Stone, Anita I

    2007-02-01

    Tropical forests are characterized by marked temporal and spatial variation in productivity, and many primates face foraging problems associated with seasonal shifts in fruit availability. In this study, I examined seasonal changes in diet and foraging behaviors of two groups of squirrel monkeys (Saimiri sciureus), studied for 12 months in Eastern Brazilian Amazonia, an area characterized by seasonal rainfall. Squirrel monkeys were primarily insectivorous (79% of feeding and foraging time), with fruit consumption highest during the rainy season. Although monkeys fed from 68 plant species, fruit of Attalea maripa palms accounted for 28% of annual fruit-feeding records. Dietary shifts in the dry season were correlated with a decline in ripe A. maripa fruits. Despite pronounced seasonal variation in rainfall and fruit abundance, foraging efficiency, travel time, and distance traveled remained stable between seasons. Instead, squirrel monkeys at this Eastern Amazonian site primarily dealt with the seasonal decline in fruit by showing dietary flexibility. Consumption of insects, flowers, and exudates increased during the dry season. In particular, their foraging behavior at this time strongly resembled that of tamarins (Saguinus sp.) and consisted of heavy use of seed-pod exudates and specialized foraging on large-bodied orthopterans near the forest floor. Comparisons with squirrel monkeys at other locations indicate that, across their geographic range, Saimiri use a variety of behavioral tactics during reduced periods of fruit availability.

  11. Excavation of red squirrel middens by grizzly bears in the whitebark pine zone

    USGS Publications Warehouse

    Mattson, D.J.; Reinhart, D.P.

    1997-01-01

    7. Grizzly bears would benefit from the minimization of roads and other human facilities in the whitebark pine zone and from increases in the availability of whitebark pine seeds, potentially achieved by increasing the numbers of cone-producing whitebark pine trees, especially in lower elevations of the whitebark pine zone where red squirrels are more abundant.

  12. Social Behavior in Interacting Squirrel Monkeys with Differential Nutritional and Environmental Histories.

    ERIC Educational Resources Information Center

    Chappell, Patricia F.

    This paper reports an observational study of the effects of handling on the social behavior of squirrel monkeys who received a protein deficient diet. After birth, experimental animals received a low-protein diet for a 6-week period. A subgroup of these animals were handled between 3 and 12 weeks of age. All of the animals interacted (in four…

  13. Pattern of maternal circulating CRH in laboratory-housed squirrel and owl monkeys.

    PubMed

    Power, M L; Williams, L E; Gibson, S V; Schulkin, J; Helfers, J; Zorrilla, E P

    2010-11-01

    The anthropoid primate placenta appears to be unique in producing corticotropin-releasing hormone (CRH). Placental CRH is involved in an endocrine circuit key to the production of estrogens during pregnancy. CRH induces cortisol production by the maternal and fetal adrenal glands, leading to further placental CRH production. CRH also stimulates the fetal adrenal glands to produce dehydroepiandrostendione sulfate (DHEAS), which the placenta converts into estrogens. There are at least two patterns of maternal circulating CRH across gestation among anthropoids. Monkeys examined to date (Papio and Callithrix) have an early-to-mid gestational peak of circulating CRH, followed by a steady decline to a plateau level, with a possible rise near parturition. In contrast, humans and great apes have an exponential rise in circulating CRH peaking at parturition. To further document and compare patterns of maternal circulating CRH in anthropoid primates, we collected monthly blood samples from 14 squirrel monkeys (Saimiri boliviensis) and ten owl monkeys (Aotus nancymaae) during pregnancy. CRH immunoreactivity was measured from extracted plasma by using solid-phase radioimmunoassay. Both squirrel and owl monkeys displayed a mid-gestational peak in circulating CRH: days 45-65 of the 152-day gestation for squirrel monkeys (mean±SEM CRH=2,694±276 pg/ml) and days 60-80 of the 133-day gestation for owl monkeys (9,871±974 pg/ml). In squirrel monkeys, circulating CRH declined to 36% of mean peak value by 2 weeks before parturition and then appeared to increase; the best model for circulating CRH over gestation in squirrel monkeys was a cubic function, similar to previous results for baboons and marmosets. In owl monkeys, circulating CRH appeared to reach plateau with no subsequent significant decline approaching parturition, although a cubic function was the best fit. This study provides additional evidence for a mid-gestational peak of maternal circulating CRH in ancestral

  14. Biochemical adaptations of mammalian hibernation: exploring squirrels as a perspective model for naturally induced reversible insulin resistance.

    PubMed

    Wu, C-W; Biggar, K K; Storey, K B

    2013-01-01

    An important disease among human metabolic disorders is type 2 diabetes mellitus. This disorder involves multiple physiological defects that result from high blood glucose content and eventually lead to the onset of insulin resistance. The combination of insulin resistance, increased glucose production, and decreased insulin secretion creates a diabetic metabolic environment that leads to a lifetime of management. Appropriate models are critical for the success of research. As such, a unique model providing insight into the mechanisms of reversible insulin resistance is mammalian hibernation. Hibernators, such as ground squirrels and bats, are excellent examples of animals exhibiting reversible insulin resistance, for which a rapid increase in body weight is required prior to entry into dormancy. Hibernator studies have shown differential regulation of specific molecular pathways involved in reversible resistance to insulin. The present review focuses on this growing area of research and the molecular mechanisms that regulate glucose homeostasis, and explores the roles of the Akt signaling pathway during hibernation. Here, we propose a link between hibernation, a well-documented response to periods of environmental stress, and reversible insulin resistance, potentially facilitated by key alterations in the Akt signaling network, PPAR-γ/PGC-1α regulation, and non-coding RNA expression. Coincidentally, many of the same pathways are frequently found to be dysregulated during insulin resistance in human type 2 diabetes. Hence, the molecular networks that may regulate reversible insulin resistance in hibernating mammals represent a novel approach by providing insight into medical treatment of insulin resistance in humans.

  15. High incidence of the gullet worm, Gongylonema pulchrum, in a squirrel monkey colony in a zoological garden in Japan.

    PubMed

    Sato, Hiroshi; Une, Yumi; Takada, Mariko

    2005-01-20

    Histological examination revealed the gullet worm (Gongylonema pulchrum) embedded in the lingual mucosa of two of four dead Bolivian squirrel monkeys (Saimiri boliviensis) from a zoological garden in Kyushu, Japan. The zoo had kept the monkeys as a colony of approximately 80-100 individuals in a moated, open ground since 1981. To assess the incidence of G. pulchrum infection in this colony, lingual scraping with disposable plastic sticks was conducted in February during 2 consecutive years (2003 and 2004). The oval, thick-shelled egg containing a larva was found in 15 of 27 arbitrarily-chosen adult monkeys (55.5%) in 2003, and 27 of 106 monkeys (25.5%) in 2004. Infection of other zoo-kept mammals with G. pulchrum was not assessed. Since the gullet worm infects a variety of mammals including primates as natural definitive hosts, and dung beetles and cockroaches as intermediate hosts, the zoological garden may provide an ideal environment for the parasite. Zoo veterinarians should be aware of this disease in kept mammals, and should consider in the case of primates, monthly or bimonthly prophylactic anthelmintic treatment.

  16. Intrinsic innervation of the Persian squirrel (Sciurus anomalus) ileum.

    PubMed

    Sadeghinezhad, J; Tootian, Z; Latorre, R; Sorteni, C; Chiocchetti, R

    2013-06-01

    Most investigations related to the characterisation of the enteric nervous system (ENS) are pivoted on the intestine of small rodents, but few studies are available on the ENS of wild or 'unconventional' rodents. Anti-PGP 9.5 and anti-Hu antibodies were utilised to recognise the distribution pattern of neuronal cell bodies and fibres of the ileum of the Persian squirrel (Sciurus anomalus) ENS. The percentages of subclasses of enteric neurones in the total neuronal population were investigated by neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT), calcitonin gene-related peptide (CGRP), substance P (SP), and calbindin (CALB). Myenteric plexus (MP) and submucosal plexus (SMP) neurones showing nNOS immunoreactivity (IR) were 41±4% and 11±6%, respectively, whereas cells expressing ChAT-IR were 56±9% and 74±16%, respectively. nNOS-IR was co-expressed by 21±2% and 9±4% of the MP and SMP cholinergic neurones, respectively, whereas the nNOS-IR MP and SMP neurones co-expressing ChAT-IR were 86±6% and 89±2%, respectively. CGRP-IR and SP-IR were expressed, respectively, by 13±5% and 6±3% of MP and 18±2% and 2±2% of SMP neurones. CALB-IR was expressed by 22±8% and 56±14% of MP and SMP neurones, respectively. MP and SMP cholinergic neurones co-expressed nNOS-IR (21±2% and 9±4%, respectively) and a very high percentage of nNOS-IR neurones showed ChAT-IR (86±6% and 89±2%, respectively). MP and SMP CALB-IR neurones co-expressed ChAT-IR (100% and 63±11%, respectively) and CGRP-IR (89±5% and 26±7%, respectively). Our data might contribute to the neuroanatomical knowledge of the gastrointestinal tract in exotic mammals and provide a comparison with the available data on other mammals.

  17. Phenotype and Age Differences in Blood Gas Characteristics, Electrolytes, Hemoglobin, Plasma Glucose and Cortisol in Female Squirrel Monkeys

    NASA Technical Reports Server (NTRS)

    Brizzee, K. R.; Ordy, J. M.; Dunlap, W. P.; Kendrick, R.; Wengenack, T. M.

    1988-01-01

    Due to its small size, lower cost, tractable nature, successful breeding in captivity and its status near the middle of the primate phylogenetic scale, the squirrel monkey has become an attractive primate model for basic and biomedical research. Although the squirrel monkey now is being used more extensively in many laboratories with diverse interests, only fragmentary reports have been published regarding basic physiological characteristics, or baseline blood reference values of different phenotypes, particularly blood gases, hematology and serum chemical constituents. It is becoming recognized increasingly that these baseline blood reference values are important not only in the care and maintenance of the squirrel monkey, but are critical for assessing normal physiological status, as well as the effects of various experimental treatments. The purpose of this study was to compare differences in blood gases, electrolytes, hematology, blood glucose and cortisol among young and old Bolivian (Roman type) and Colombian (Gothic type) phenotypes of the squirrel monkey.

  18. [Squirrel monkey--an ideal primate (correction of prmate) model of space physiology].

    PubMed

    Matsunami, K

    1997-06-01

    Investigation of the vestibulo-ocular system of the squirrel monkey was reviewed in consideration of space motion sickness (SMS), or which is recently more often termed as space adaptation syndrome (SAS). Since the first launching of the space satellite, Sputnik [correction of Sputonik] in October 1957, many experiments were carried out in biological and medical fields. A various kind of creatures were used as experimental models from protozoa to human beings. Rats and monkeys are most favorite animals, particularly the non-human primate seems to be the one, because of its phylogenetic relatives akin to the human beings. Chimpanzees, rhesus monkeys, pig tailed-monkeys, red-faced monkeys and squirrel monkeys have been used mostly in American space experiments. Russian used rhesus monkeys. Among these, however, the squirrel monkey has an advantage of the small size of the body, ranging from 600- l000g in adult. This small size as a primate is very advantageous in experiments conducted in a narrow room of the space satellite or shuttle because of its space-saving. The squirrel monkey has another advantage to rear easily as is demonstrated to keep it as a pet. Accordingly, this petit animal provides us a good animal model in biological and medical experiments in space craft. The size of the brain of the squirrel monkey is extraordinary large relative to the body size, which is even superior to that of the human beings. This is partly owed to enlargement of the occipito-temporal cortices, which are forced to well develop for processing a huge amount of audio-visual information indispensable to the arboreal habitant to survive in tropical forest. The vestibular system of the squirrel monkey seems to be the most superior as well, when judged from it relative size of the vestibular nuclear complex. Balancing on swinging twigs or jumping from tree to tree developed the capability of this equilibrium system. Fernandez, Goldberg and his collaborators used the squirrel monkey

  19. Capture of syncytin-Mar1, a Fusogenic Endogenous Retroviral Envelope Gene Involved in Placentation in the Rodentia Squirrel-Related Clade

    PubMed Central

    Redelsperger, François; Cornelis, Guillaume; Vernochet, Cécile; Tennant, Bud C.; Catzeflis, François; Mulot, Baptiste; Heidmann, Odile; Dupressoir, Anne

    2014-01-01

    ABSTRACT Syncytin genes are fusogenic envelope protein (env) genes of retroviral origin that have been captured for a function in placentation. Within rodents, two such genes have previously been identified in the mouse-related clade, allowing a demonstration of their essential role via knockout mice. Here, we searched for similar genes in a second major clade of the Rodentia order, the squirrel-related clade, taking advantage of the complete sequencing of the ground squirrel Ictidomys tridecemlineatus genome. In silico search for env genes with full coding capacity identified several candidate genes with one displaying placenta-specific expression, as revealed by quantitative reverse transcription-PCR analysis of a large panel of tissues. This gene belongs to a degenerate endogenous retroviral element, with recognizable hallmarks of an integrated provirus. Cloning of the gene in an expression vector for ex vivo cell-cell fusion and pseudotype assays demonstrated fusogenicity on a large panel of mammalian cells. In situ hybridization on placenta sections showed specific expression in domains where trophoblast cells fuse into a syncytiotrophoblast at the fetomaternal interface, consistent with a role in syncytium formation. Finally, we show that the gene is conserved among the tribe Marmotini, thus dating its capture back to about at least 25 million years ago, with evidence for purifying selection and conservation of fusogenic activity. This gene that we named syncytin-Mar1 is distinct from all seven Syncytin genes identified to date in eutherian mammals and is likely to be a major effector of placentation in its related clade. IMPORTANCE Syncytin genes are fusogenic envelope genes of retroviral origin, ancestrally captured for a function in placentation. Within rodents, two such genes had been previously identified in the mouse-related clade. Here, in the squirrel-related rodent clade, we identified the envelope gene of an endogenous retrovirus with all the

  20. Capture of syncytin-Mar1, a fusogenic endogenous retroviral envelope gene involved in placentation in the Rodentia squirrel-related clade.

    PubMed

    Redelsperger, François; Cornelis, Guillaume; Vernochet, Cécile; Tennant, Bud C; Catzeflis, François; Mulot, Baptiste; Heidmann, Odile; Heidmann, Thierry; Dupressoir, Anne

    2014-07-01

    Syncytin genes are fusogenic envelope protein (env) genes of retroviral origin that have been captured for a function in placentation. Within rodents, two such genes have previously been identified in the mouse-related clade, allowing a demonstration of their essential role via knockout mice. Here, we searched for similar genes in a second major clade of the Rodentia order, the squirrel-related clade, taking advantage of the complete sequencing of the ground squirrel Ictidomys tridecemlineatus genome. In silico search for env genes with full coding capacity identified several candidate genes with one displaying placenta-specific expression, as revealed by quantitative reverse transcription-PCR analysis of a large panel of tissues. This gene belongs to a degenerate endogenous retroviral element, with recognizable hallmarks of an integrated provirus. Cloning of the gene in an expression vector for ex vivo cell-cell fusion and pseudotype assays demonstrated fusogenicity on a large panel of mammalian cells. In situ hybridization on placenta sections showed specific expression in domains where trophoblast cells fuse into a syncytiotrophoblast at the fetomaternal interface, consistent with a role in syncytium formation. Finally, we show that the gene is conserved among the tribe Marmotini, thus dating its capture back to about at least 25 million years ago, with evidence for purifying selection and conservation of fusogenic activity. This gene that we named syncytin-Mar1 is distinct from all seven Syncytin genes identified to date in eutherian mammals and is likely to be a major effector of placentation in its related clade. Importance: Syncytin genes are fusogenic envelope genes of retroviral origin, ancestrally captured for a function in placentation. Within rodents, two such genes had been previously identified in the mouse-related clade. Here, in the squirrel-related rodent clade, we identified the envelope gene of an endogenous retrovirus with all the features of a

  1. Theoretical analysis of a YBCO squirrel-cage type induction motor based on an equivalent circuit

    NASA Astrophysics Data System (ADS)

    Morita, G.; Nakamura, T.; Muta, I.

    2006-06-01

    A HTS induction motor, with a HTS squirrel-cage rotor, is analysed using an electrical equivalent circuit. The squirrel-cage winding in the rotor consists of rotor bars and end rings, and both are considered to be made of YBCO film conductors. A wide range of electric field versus current density in YBCO film is formulated based on the Weibull function, and analysed as a non-linear resistance in the equivalent circuit. It is shown that starting and accelerating torques of the HTS induction motor are improved drastically compared to those of a conventional induction motor. Furthermore, large synchronous torque can also be realized by trapping the magnetic flux in the rotor circuit because of the persistent current mode.

  2. First case of Echinococcus multilocularis infection in a zoo-housed flying squirrel (Pteromys volans orii).

    PubMed

    Oikawa, Eri; Shimura, Ryoji; Nishimura, Maki; Furuoka, Hidefumi

    2013-01-01

    A 33 month-old male flying squirrel kept in a zoo developed progressive dyspnea and died. Macroscopically, the liver and lung were enlarged with numerous nodular vesicles. Histologically, these organs were replaced by numerous collapsed vesicles demarcated by fibrous tissues. The cysts lined by a cellular, germinal layer contained numerous brood capsules with abundant production of well-developed protoscolices. Protoscolices were about 80-100 μm in diameter, and had hooks being visible as refractive structures. This zoo locates in the east of Hokkaido where is an endemic area of Echinococcus multilocularis infection. From epidemiology and pathological findings, this animal was diagnosed as E.multilocularis infection. This report describes the pathology of the first case of E. multilocularis infection in a flying squirrel.

  3. Autoshaping and automaintenance of a key-press response in squirrel monkeys

    PubMed Central

    Gamzu, Elkan; Schwam, Elias

    1974-01-01

    Following exposure for a minimum of 500 to 600 trials, three of four naive squirrel monkeys eventually pressed a response key, illumination of which always preceded delivery of a food pellet. Three other naive monkeys did not press the key when the pellets were delivered randomly with respect to key illumination. Despite some similarities to autoshaping using pigeons, the data indicate many points of difference when squirrel monkeys are used as subjects. Although key-food pairings were shown to be important in the acquisition of the key-press response, they were ineffective in maintaining the response when either a negative response-reinforcer dependency was introduced, or when there was no scheduled response-reinforcer dependency (fixed trial). Not all demonstrations of autoshaping can be considered to be under the control of those processes that are primarily responsible for the phenomena obtained in pigeons. PMID:16811749

  4. CXCR4 homologues of gibbon ape, African green monkey, squirrel monkey, and cotton-top marmoset.

    PubMed

    Zubair, S; Metzenberg, S

    2000-08-10

    CXCR4 gene homologues were isolated from an ape (gibbon), an Old World monkey (African green monkey), and two New World monkeys (squirrel monkey and cotton-top marmoset), and their DNA sequences determined. The squirrel monkey and cotton-top marmoset CXCR4 sequences more closely resemble homologues from apes than Old World monkeys, a pattern not seen for the related chemokine receptor CCR5. The African green monkey CXCR4 gene is similar to its homologue in baboon, a pattern that has also been seen among CCR5 homologues. The gibbon CXCR4 contains the first polymorphisms recognized in ape homologues, the human and chimpanzee CXCR4 proteins being identical, and two of these three differences are also observed in one or more Old World monkey homologues. While 18 positions within CXCR4 are now known to be polymorphic in primates, 7 of these polymorphisms have been observed in multiple examples and 11 have been observed only once.

  5. First report of Polyplax sp. in a Persian squirrel (Scuirus anomalus) in Tabriz, Northwest of Iran.

    PubMed

    Shirazi, Shahrokh; Bahadori, Farhad; Mostafaei, Tayebeh-Sadat; Ronaghi, Hooman

    2013-01-01

    The Persian squirrel (Scuirus anomalus) has a long furry tail, which is longer than half of the body, and lives in the Zagros forest. It is distributed in the west and northeast of Asia. In the summer 2011 a Persian squirrel with signs of hair loss and itch in head and tail was referred to the veterinary clinic. There were arthropods in the lesion in the first survey. Many of these parasites were collected and were sent to Parasitology Laboratory of Science and Research University in Tehran. Samples were processed and were identified according to lices diagnostic keys using a light microscope. Lice that were sent to the national parasitology museum were identified as Polyplax sp. too.

  6. The evolution of urgency-based and functionally referential alarm calls in ground-dwelling species.

    PubMed

    Furrer, Roman D; Manser, Marta B

    2009-03-01

    A major evolutionary force driving functionally referential alarm calls is the need for different strategies to escape various predator types in complex structured habitats. In contrast, a single escape strategy appears to be sufficient in less-structured open habitats, and under such conditions urgency-dependent alarm calls may be favored. Nevertheless, some species, such as meerkats (Suricata suricatta), have evolved functionally referential alarm calls despite living in open areas, using only bolt-holes for retreat. To understand the evolution of different alarm call systems, we investigated the calls of sympatric Cape ground squirrels (Xerus inauris) and compared their antipredator and foraging behavior with that of meerkats. Cape ground squirrels emitted urgency-dependent alarm calls and responded to playbacks depending on urgency, not predator type. Vigilance behavior and habitat use differed between the two species. Meerkats roam widely to find prey and for efficient foraging depend on coordinated predator vigilance and escape behavior. As herbivores with smaller territories, Cape ground squirrels depend less on coordinated antipredator behavior, and urgency-dependent alarm calls encode all essential information. We conclude that habitat complexity does not explain the evolution of functionally referential alarm calls in all species, and other constraints, such as the need to coordinate group movements to maintain foraging efficiency, could be more relevant.

  7. Mapping and monitoring Mount Graham red squirrel habitat with Lidar and Landsat imagery

    USGS Publications Warehouse

    Hatten, James R.

    2014-01-01

    The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is an endemic subspecies located in the Pinaleño Mountains of southeast Arizona. Living in a conifer forest on a sky-island surrounded by desert, the Mount Graham red squirrel is one of the rarest mammals in North America. Over the last two decades, drought, insect infestations, and fire destroyed much of its habitat. A federal recovery team is working on a plan to recover the squirrel and detailed information is necessary on its habitat requirements and population dynamics. Toward that goal I developed and compared three probabilistic models of Mount Graham red squirrel habitat with a geographic information system and logistic regression. Each model contained the same topographic variables (slope, aspect, elevation), but the Landsat model contained a greenness variable (Normalized Difference Vegetation Index) extracted from Landsat, the Lidar model contained three forest-inventory variables extracted from lidar, while the Hybrid model contained Landsat and lidar variables. The Hybrid model produced the best habitat classification accuracy, followed by the Landsat and Lidar models, respectively. Landsat-derived forest greenness was the best predictor of habitat, followed by topographic (elevation, slope, aspect) and lidar (tree height, canopy bulk density, and live basal area) variables, respectively. The Landsat model's probabilities were significantly correlated with all 12 lidar variables, indicating its utility for habitat mapping. While the Hybrid model produced the best classification results, only the Landsat model was suitable for creating a habitat time series or habitat–population function between 1986 and 2013. The techniques I highlight should prove valuable in the development of Landsat- or lidar-based habitat models range wide.

  8. Evaluation of the Squirrel Monkey (Saimiri sciureus) as an Experimental Animal Model for Dysbaric Osteonecrosis.

    DTIC Science & Technology

    1976-01-07

    Osteonecrosis , Squirrel monkeys, Dysbarism, Decompression AM STRACT (Coalftwo Af VOW0 df it 060006 Red AV Ihib 6 In an attempt to develop an animal model for...subclinical decomipression sickness was produced. No clinical, radiologic, or post-mortem evidence of osteonecrosis was discovered during either the 6...ANIMAL MODE[L FOR DYSBARIC OSTEONECROSIS Uwsimemnt Ctoilo Jamm L. Kuppwr, USAF VC Naval Medical Rearchh and Doevlwomfnt Commxw SM~~?000.OI .01 .7022 A

  9. Thalamic connections of architectonic subdivisions of temporal cortex in grey squirrels (Sciurus carolinenesis)

    PubMed Central

    Wong, Peiyan; Gharbawie, Omar A.; Luethke, Lynn E.; Kaas, Jon H.

    2008-01-01

    The temporal cortex of grey squirrels contains three architectonically distinct regions. One of these regions, the temporal anterior (Ta) region has been identified in previous physiological and anatomical studies as containing several areas that are largely auditory in function. Consistent with this evidence, Ta has architectonic features that are internally somewhat variable, but overall sensory in nature. In contrast, the caudally adjoining temporal intermediate region (Ti) has architectonic features that suggest higher order and possibly multisensory processing. Finally, the most caudal region, composed of previously defined temporal medial (Tm) and temporal posterior (Tp) fields, again has more of the appearance of sensory cortex. To better understand their functional roles, we injected anatomical tracers into these regions to reveal their thalamic connections. As expected, the dorsal portion of Ta, containing two primary or primary-like auditory areas, received inputs from the ventral and magnocellular divisions of the auditory medial geniculate complex, MGv and MGm. The most caudal region, Tm plus Tp, received inputs from the large visual pulvinar of squirrels, possibly accounting for the sensory architectonic characteristics of this region. However, Tp additionally receives inputs from the magnocellular (MGm) and dorsal (MGd) divisions of the medial geniculate complex, implicating Tp in bisensory processing. Finally, the middle region, Ti, had auditory inputs from MGd and MGm, but not from the visual pulvinar, providing evidence that Ti has higher-order auditory functions. The results indicate that the architectonically distinct regions of temporal cortex of squirrels are also functionally distinct. Understanding how temporal cortex is functionally organized in squirrels can guide interpretations of temporal cortex organization in other rodents where architectonic subdivisions are not as obvious. PMID:18666125

  10. Tail function during arboreal quadrupedalism in squirrel monkeys (Saimiri boliviensis) and tamarins (Saguinus oedipus).

    PubMed

    Young, Jesse W; Russo, Gabrielle A; Fellmann, Connie D; Thatikunta, Meena A; Chadwell, Brad A

    2015-10-01

    The need to maintain stability on narrow branches is often presented as a major selective force shaping primate morphology, with adaptations to facilitate grasping receiving particular attention. The functional importance of a long and mobile tail for maintaining arboreal stability has been comparatively understudied. Tails can facilitate arboreal balance by acting as either static counterbalances or dynamic inertial appendages able to modulate whole-body angular momentum. We investigate associations between tail use and inferred grasping ability in two closely related cebid platyrrhines-cotton-top tamarins (Saguinus oedipus) and black-capped squirrel monkeys (Saimiri boliviensis). Using high-speed videography of captive monkeys moving on 3.2 cm diameter poles, we specifically test the hypothesis that squirrel monkeys (characterized by grasping extremities with long digits) will be less dependent on the tail for balance than tamarins (characterized by claw-like nails, short digits, and a reduced hallux). Tamarins have relatively longer tails than squirrel monkeys, move their tails through greater angular amplitudes, at higher angular velocities, and with greater angular accelerations, suggesting dynamic use of tail to regulate whole-body angular momentum. By contrast, squirrel monkeys generally hold their tails in a comparatively stationary posture and at more depressed angles, suggesting a static counterbalancing mechanism. This study, the first empirical test of functional tradeoffs between grasping ability and tail use in arboreal primates, suggests a critical role for the tail in maintaining stability during arboreal quadrupedalism. Our findings have the potential to inform our functional understanding of tail loss during primate evolution.

  11. Ovarian stimulation of squirrel monkeys (Saimiri boliviensis boliviensis) using pregnant mare serum gonadotropin.

    PubMed

    Schuler, A Michele; Westberry, Jenne M; Scammell, Jonathan G; Abee, Christian R; Kuehl, Thomas J; Gordon, Jon W

    2006-02-01

    The application of assisted reproductive technologies (ART) to nonhuman primates has created opportunities for improving reproductive management in breeding colonies, and for creation of new animal models by genetic modification. One impediment to the application of ART in Saimiri spp. has been the lack of an effective gonadotropin preparation for ovarian stimulation. Pregnant mare serum gonadotropin (PMSG) is inexpensive and readily available, but its repeated use in rhesus monkeys has been associated with induction of a refractory state. We have compared PMSG to recombinant human follicle stimulating hormone (rhFSH) for controlled ovarian stimulation in Bolivian squirrel monkeys. Groups of mature squirrel monkeys received rhFSH (75 IU daily) or PMSG (250 IU twice daily) by subcutaneous injection for 4 d during the breeding season (November to January) or nonbreeding season (March to September). Serum estradiol (E2) was measured daily. Follicular growth was monitored by abdominal ultrasound. During the breeding season, PMSG induced a higher E2 response than did rhFSH, with mean E2 levels being significantly higher within 3 d of stimulation. Superior follicular development in PMSG animals was confirmed by abdominal ultrasonography. During the nonbreeding season, PMSG elicited a similar increase in serum E2 levels despite the fact that basal serum E2 is typically low during the nonbreeding season. Repeated use of PMSG (< or = 3 cycles of administration) produced no attenuation of the E2 response. We conclude that PMSG is highly effective for repeated cycles of controlled ovulation stimulation in the squirrel monkey.

  12. Natural occurrence of black-pigmented Bacteroides species in the gingival crevice of the squirrel monkey.

    PubMed Central

    Clark, W B; Magnusson, I; Abee, C; Collins, B; Beem, J E; McArthur, W P

    1988-01-01

    The objective of this study was to determine whether the squirrel monkey (Saimiri scuireus) is indigenously colonized with black-pigmented bacteroides (BPB) resembling human Bacteroides gingivalis and Bacteroides intermedius (suspected periodontal pathogens) and to determine the usefulness of the squirrel monkey as an in vivo model for studying colonization by putative pathogens. We assayed the subgingival plaques of 138 monkeys of various ages and in four different colonies for the presence of anaerobic BPB microorganisms. We also tested half the animals for the presence of Actinobacillus actinomycetemcomitans. Clinical indices and levels of serum antibody to B. gingivalis were recorded. We detected BPB in 50% of the animals and A. actinomycetemcomitans in 69% of the animals. The presence of BPB was generally associated with increased age, increased gingival index, presence of calculus, and increased levels of serum antibody. These data indicate that the squirrel monkey may be a good model for studying the parameters of natural infection of the gingival crevice with suspected periodontopathogenic BPB microorganisms. PMID:3410543

  13. Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels (Glaucomys sabrinus).

    PubMed

    Bahlman, Joseph W; Swartz, Sharon M; Riskin, Daniel K; Breuer, Kenneth S

    2013-03-06

    Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60-125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels (Glaucomys sabrinus) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight.

  14. Can squirrel monkeys (Saimiri sciureus) plan for the future? Studies of temporal myopia in food choice.

    PubMed

    McKenzie, Tammy; Cherman, Taryn; Bird, Leanne R; Naqshbandi, Mariam; Roberts, William A

    2004-11-01

    In seven experiments, 2 squirrel monkeys were given choices between arrays of food that varied in the quantity offered. In Experiments 1-5, the monkeys were offered choices between quantities of the same food that varied in a 2:1 ratio. The squirrel monkeys failed to show the temporal myopia effect or a decrease in preference for the larger quantity as the absolute number of food items offered increased. Even when given choices of 8 versus 16 peanuts and 10 versus 20 peanuts, both monkeys significantly preferred the larger quantity. An examination of the monkeys' rates of consumption indicated that 20 peanuts were consumed over a 1- to 2-h period, with eating bouts separated by periods of nonconsumption. In Experiments 6A, 6B, and 7, food was either pilfered or replenished 15 min after an initial choice, so that choice of the smaller quantity led to more total food in the long run. These manipulations caused both monkeys to reduce choice of the larger quantity, relative to baseline choice. The results suggest that squirrel monkeys anticipated the future consequences of their choices.

  15. Host-pathogen dynamics of squirrelpox virus infection in red squirrels (Sciurus vulgaris).

    PubMed

    Fiegna, C; Dagleish, M P; Coulter, L; Milne, E; Meredith, A; Finlayson, J; Di Nardo, A; McInnes, C J

    2016-01-01

    To improve our understanding of squirrelpox virus (SQPV) infection in the susceptible host, three red squirrels were challenged with wild-type SQPV via scarification of the hind-limb skin. All squirrels seroconverted to the infection by the end of the experiment (17 days post-challenge). Challenged animals suffered disease characterised by the development of multiple skin and oral lesions with rapid progression of skin lesions at the infection site by day 10 post-challenge. No internal pathological changes were found at post-mortem examination. A novel SQPV Taqman(®) Real-time PCR detected viral DNA from multiple organs, with the largest amounts consistently associated with the primary and secondary skin and oral lesions where viral replication was most likely occurring. Immunohistochemistry clearly detected viral antigen in the stratified squamous epithelium of the epidermis, tongue and the oropharyngeal mucosa-associated lymphoid tissue and was consistently associated with histological changes resulting from viral replication. The lack of internal pathological changes and the detection of relatively low levels of viral DNA when compared with primary and secondary skin lesions argue against systemic disease, although systemic spread of the virus cannot be ruled out. This study allowed a comprehensive investigation of the clinical manifestation and progression of SQPV infection with a quantitative and qualitative analysis of virus dissemination and shedding. These findings suggest two separate routes of SQPV transmission under natural conditions, with both skin and saliva playing key roles in infected red squirrels.

  16. Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels (Glaucomys sabrinus)

    PubMed Central

    Bahlman, Joseph W.; Swartz, Sharon M.; Riskin, Daniel K.; Breuer, Kenneth S.

    2013-01-01

    Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60–125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels (Glaucomys sabrinus) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight. PMID:23256188

  17. Isolation and amino acid sequences of squirrel monkey (Saimiri sciurea) insulin and glucagon

    SciTech Connect

    Yu, Jinghua ); Eng, J.; Yalow, R.S. City Univ. of New York, NY )

    1990-12-01

    It was reported two decades ago that insulin was not detectable in the glucose-stimulated state in Saimiri sciurea, the New World squirrel monkey, by a radioimmunoassay system developed with guinea pig anti-pork insulin antibody and labeled park insulin. With the same system, reasonable levels were observed in rhesus monkeys and chimpanzees. This suggested that New World monkeys, like the New World hystricomorph rodents such as the guinea pig and the coypu, might have insulins whose sequences differ markedly from those of Old World mammals. In this report the authors describe the purification and amino acid sequences of squirrel monkey insulin and glucagon. They demonstrate that the substitutions at B29, B27, A2, A4, and A17 of squirrel monkey insulin are identical with those previously found in another New World primate, the owl monkey (Aotus trivirgatus). The immunologic cross-reactivity of this insulin in their immunoassay system is only a few percent of that of human insulin. It appears that the peptides of the New World monkeys have diverged less from those of the Old World mammals than have those of the New World hystricomorph rodents. The striking improvements in peptide purification and sequencing have the potential for adding new information concerning the evolutionary divergence of species.

  18. The pineal gland of the Indian palm squirrel, Funambulus pennanti (Wroughton).

    PubMed

    Bhaskar, K S; Katti, S R; Sathyanesan, A G

    In the adult palm squirrel, F. pennanti the pineal is a club shaped, elongated structure with a connective tissue capsule. It consists of various types of pinealocytes, glial cells, neurons, nerve fibres, blood vessels and connective tissue. Two types of pinealocytes could be identified by light microscopy. They are large rounded with centrally placed nucleus, and small rounded pinealocytes. They have medium sized processes stainable with Alcian blue, periodic acid Schiff and Nissl methods. The pinealocytes are not stainable with bromophenol blue. However, they are moderately stainable with PAS, Sudan black and Baker's acid hematin. Neurons are seen either singly or in groups with axonal processes. Cystic cavities often lined by cells are a normal feature of adult squirrel pineal, and the lining cells are both pinealocytes and glial cells. Often neuronal endings are seen terminating on these lining cells. PAS positive globules were also seen inside the cysts. In some squirrel pineals, fibrous cysts with an inner core of cells are also seen. Occasionally groups of lymphocytes were also encountered in the pineal. In the fetal pineal, the cells are both larger and smaller ones and arranged in a cortex and medulla pattern and no cystic cavities are seen. The third ventricle enters the base of the pineal as pineal recess.

  19. Conditioned taste aversion and motion sickness in cats and squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Fox, Robert A.; Corcoran, Meryl Lee; Brizzee, Kenneth R.

    1991-01-01

    The relationship between vomiting and conditioned taste aversion was studied in intact cats and squirrel monkeys and in cats and squirrel monkeys in which the area postrema was ablated by thermal cautery. In cats conditioned 7-12 months after ablation of the area postrema, three successive treatments with xylazine failed to produce either vomiting or conditioned taste aversion to a novel fluid. Intact cats, however, vomited and formed a conditioned aversion. In squirrel monkeys conditioned 6 months after ablation of the area postrema, three treatments with lithium chloride failed to produce conditioned taste aversion. Intact monkeys did condition with these treatments. Neither intact nor ablated monkeys vomited or evidenced other signs of illness when injected with lithium chloride. When the same ablated cats and monkeys were exposed to a form of motion that produced vomiting prior to surgery, conditioned taste aversion can be produced after ablation of the area postrema. The utility of conditioned taste aversion as a measure of subemetic motion sickness is discussed by examining agreement and disagreement between identifications of motion sickness by conditioned taste aversion and vomiting. It is suggested that a convincing demonstration of the utility of conditioned taste aversion as a measure of nausea requires the identification of physiological correlates of nausea, and caution should be exercised when attempting to interpret conditioned taste aversion as a measure of nausea.

  20. The relationship between 3-D kinematics and gliding performance in the southern flying squirrel, Glaucomys volans.

    PubMed

    Bishop, Kristin L

    2006-02-01

    Gliding is the simplest form of flight, yet relatively little is known about its mechanics in animals. The goal of this study was to describe the body position and performance of a gliding mammal and to identify correlates between kinematics and aerodynamic performance. To do this, I used a pair of high-speed digital cameras to record a portion of the middle of glides by southern flying squirrels, Glaucomys volans. The squirrels launched from a height of 4 m and landed on a vertical pole. Reflective markers were applied to anatomical landmarks and the 3-D coordinates of these points were computed to describe the kinematics of the glides. From these data I estimated the lift and drag generated during the glide, and correlated these variables with gliding performance as measured by glide angle, glide speed and stability. In the majority of the glide sequences the squirrels accelerated in the downward direction and accelerated horizontally forward as they moved through the calibrated volume in the middle of the glide trajectory, rather than exhibiting a steady glide in which the body weight is balanced by the resultant aerodynamic force. Compared to human engineered airfoils, the angles of attack used by the squirrels were unexpectedly high, ranging from 35.4 degrees to 53.5 degrees , far above the angle of attack at which an aircraft wing would typically stall. As expected based on aerodynamic theory, there was a negative correlation between angle of attack and lift coefficient, indicating that the wings are stalled, and a positive correlation between angle of attack and drag coefficient. Also as expected, there was a negative correlation between lift-to-drag ratio and angle of attack, as increasing angle of attack produced both less lift and more drag. Within glides, there was a strong correlation between nose-down pitching rotations and limb movements that tended to increase the angle of attack of the wing membrane, suggesting that the animals actively control

  1. Use of LiDAR in the conservation management of the endangered red squirrel (Sciurus vulgaris L.)

    NASA Astrophysics Data System (ADS)

    Flaherty, Silvia; Lurz, Peter W. W.; Patenaude, Genevieve

    2014-01-01

    LiDAR remote sensing allows the direct retrieval of vegetation structure parameters and has been widely used to assess habitat quality for various species. The aim of this study is to test whether LiDAR can help in providing estimates of habitat suitability over larger scales and inform conservation management planning in stronghold areas of an endangered forest mammal, the red squirrel (Sciurus vulgaris L.). The Eurasian red squirrel is endangered in the UK and under strict legal protection. Hence, long-term habitat management is a key goal of the UK conservation strategy. This involves understanding habitat preferences of the species. In a previous study, we demonstrated the importance of forest structure for red squirrels' habitat preference. We used a general linear model (GLM) to relate the distribution and abundance of squirrel feeding signs to mean canopy closure, mean tree height, and the total number of trees at the plot level. However, this analysis was limited to a few sample areas. In the current study, we implement the GLM using LiDAR-derived explanatory variables in Abernethy Forest. Results suggest that when forest structure is considered, only 27% of the total forest area is highly suitable for red squirrel. Implications for management are discussed.

  2. Complete mitochondrial genome of the Eurasian flying squirrel Pteromys volans (Sciuromorpha, Sciuridae) and revision of rodent phylogeny.

    PubMed

    Ryu, Shi Hyun; Kwak, Min Jung; Hwang, Ui Wook

    2013-02-01

    In this study, the complete mitochondrial genome of the Eurasian flying squirrel Pteromys volans (Rodentia, Sciuromorpha, Sciuridae) was sequenced and characterized in detail. The entire mitochondrial genome of P. volans consisted of 16,513 bp and contained 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and two non-coding regions. Its gene arrangement pattern was consistent with the mammalian ground pattern. The overall base composition and AT contents were similar to those of other rodent mitochondrial genomes. The light-strand origin generally identified between tRNA ( Asn ) and tRNA ( Cys ) consisted of a secondary structure with an 11-bp stem and an 11-bp loop. The large control region was constructed of three characteristic domains, ETAS, CD, and CSB without any repeat sequences. Each domain contained ETAS1, subsequences A, B, and C, and CSB1, respectively. In order to examine phylogenetic contentious issues of the monophyly of rodents and phylogenetic relationships among five rodent suborders, here, phylogenetic analyses based on nucleotide sequence data of the 35 rodent and 3 lagomorph mitochondrial genomes were performed using the Bayesian inference and maximum likelihood method. The result strongly supported the rodent monophyly with high node confidence values (BP 100 % in ML and BPP 1.00 in BI) and also monophylies of four rodent suborders (BP 85-100 % in ML and BPP 1.00 in BI), except for Anomalumorpha in which only one species was examined here. Also, phylogenetic relationships among the five rodent suborders were suggested and discussed in detail.

  3. Yersiniosis caused by Yersinia pseudotuberculosis in captive toucans (Ramphastidae) and a Japanese squirrel (Sciurus lis) in zoological gardens in Japan.

    PubMed

    Nakamura, Shin-ichi; Hayashidani, Hideki; Sotohira, Yukari; Une, Yumi

    2016-02-01

    Two captive Keel-billed toucans and a Chestnut-mandibled toucan in another zoological garden died suddenly without any pre-existing symptoms, and three months later, a Japanese squirrel died of diarrhea. All these animals showed necrotic enteritis and multifocal necrosis in the liver and spleen with Gram negative bacilli. The bacilli showed strong positive immunolabeling for Yersinia pseudotuberculosis O4 in the Keel-billed toucans, Y. pseudotuberculosis O2 in the Chestnut-mandibled toucan and Y. pseudotuberculosis O1 in the Japanese squirrel, while Y. pseudotuberculosis 4b, 2b and 1b were respectively isolated from the lesions. To our knowledge, this might be the first reported case of fatal yersiniosis in a Japanese squirrel in the world as well as in toucans in Japan.

  4. Polyamines in the lateral vestibular nuclei of the squirrel monkey and their potential role in vestibular compensation

    NASA Technical Reports Server (NTRS)

    Henley, C.; Igarashi, M.

    1993-01-01

    Polyamine synthesis increases in response to injurious stimuli including axotomy and denervation. Reduced eye nystagmus and head-deviation have been observed in unilateral labyrinthectomized (UL) guinea pigs treated with an inhibitor of polyamine synthesis, alpha-difluoromethylornithine (DFMO). We quantified polyamines in the lateral vestibular nuclei (LVN) of control and UL squirrel monkeys during the phase of vestibular compensation (VC) and performed an experiment to determine if DFMO reduces nystagmus previously observed in the guinea pig. Polyamines were detected in the LVN of control and UL squirrel monkeys. Putrescine and spermidine increased in the ipsilateral LVN 3 days after UL with no change in the contralateral LVN. No left-right differences were noted in the 5-day post-UL monkey. DFMO reduced nystagmus in a UL squirrel monkey. These findings suggest that polyamines are important in vestibular function and may contribute to nystagmus observed in VC.

  5. Catenotaenia dendritica (Cestoda: Catenotaeniidae) and Three Ectoparasite Species in the Red Squirrel, Sciurus vulgaris, from Cheongju, Korea.

    PubMed

    Choe, Seongjun; Lee, Dongmin; Park, Hansol; Jeon, Hyeong-Kyu; Lee, Youngsun; Na, Ki-Jeong; Lee, In-Yong; Eom, Keeseon S

    2016-08-01

    Parasites are recorded from the red squirrel, Sciurus vulgaris, from Cheongju, the Republic of Korea. A total of 5 road-killed squirrels were thoroughly examined for internal and external parasites from November 2011 to May 2014. Total 4 parasite species, including 1 tapeworm and 3 ectoparasite species were recovered. They were morphologically identified as Catenotaenia dendritica (Cestoda: Catenotaeniidae), Hirstionyssus sciurinus, Leptotrombidium pallidum, and Ceratophyllus (Monopsyllus) indages. Among them, C. dendritica and H. sciurinus are recorded for the first time in the Korean parasite fauna. In addition, the possibility that the red squirrel could act as a reservoir host for a zoonotic disease like tsutsugamushi disease with L. pallidum as its vector has been raised.

  6. Catenotaenia dendritica (Cestoda: Catenotaeniidae) and Three Ectoparasite Species in the Red Squirrel, Sciurus vulgaris, from Cheongju, Korea

    PubMed Central

    Choe, Seongjun; Lee, Dongmin; Park, Hansol; Jeon, Hyeong-Kyu; Lee, Youngsun; Na, Ki-Jeong; Lee, In-Yong; Eom, Keeseon S.

    2016-01-01

    Parasites are recorded from the red squirrel, Sciurus vulgaris, from Cheongju, the Republic of Korea. A total of 5 road-killed squirrels were thoroughly examined for internal and external parasites from November 2011 to May 2014. Total 4 parasite species, including 1 tapeworm and 3 ectoparasite species were recovered. They were morphologically identified as Catenotaenia dendritica (Cestoda: Catenotaeniidae), Hirstionyssus sciurinus, Leptotrombidium pallidum, and Ceratophyllus (Monopsyllus) indages. Among them, C. dendritica and H. sciurinus are recorded for the first time in the Korean parasite fauna. In addition, the possibility that the red squirrel could act as a reservoir host for a zoonotic disease like tsutsugamushi disease with L. pallidum as its vector has been raised. PMID:27658604

  7. Thinning of young Douglas-fir forests decreases density of northern flying squirrels in the Oregon Cascades

    USGS Publications Warehouse

    Manning, Tom; Hagar, Joan C.; McComb, Brenda C.

    2012-01-01

    Large-scale commercial thinning of young forests in the Pacific Northwest is currently promoted on public lands to accelerate the development of late-seral forest structure for the benefit of wildlife species such as northern spotted owls (Strix occidentalis caurina) and their prey, including the northern flying squirrel (Glaucomys sabrinus). Attempts to measure the impact of commercial thinning on northern flying squirrels have mostly addressed short-term effects (2–5 years post-thinning) and the few published studies of longer-term results have been contradictory. We measured densities of northern flying squirrels 11–13 years after thinning of young (55–65 years) Douglas-fir forest stands in the Cascade Range of Oregon, as part of the Young Stand Thinning & Diversity Study. The study includes four replicate blocks, each consisting of an unthinned control stand and one stand each of the following thinning treatments: Heavy Thin; Light Thin; and Light Thin with Gaps. Thinning decreased density of northern flying squirrels, and squirrel densities were significantly lower in heavily thinned stands than in more lightly thinned stands. Regression analysis revealed a strong positive relationship of flying squirrel density with density of large (>30 cm diameter) standing dead trees and a negative relationship with percent cover of low understory shrubs. Maintaining sufficient area and connectivity of dense, closed canopy forest is recommended as a strategy to assure that long-term goals of promoting late-seral structure do not conflict with short-term habitat requirements of this important species.

  8. Effect of macular ablation on frequency and latency of motion-induced emesis in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Brizzee, Kenneth R.; Igarashi, Makoto

    1986-01-01

    Three previously motion-emetic sensitive squirrel monkeys were rendered refractory to a standard motion-emetic regimen by a two-stage utriculosacculectomy procedure which preserved the cristae ampullares of semicircular canals. Three nonoperated control squirrel monkeys tested on the same motion-emetic regimen time schedule as the operated animals remained motion-emetic sensitive with regard to incidence, frequency, and latency of motion-induced emetic responses. Following a sham surgical procedure (stapedectomy) performed on two of the latter animals and one additional new animal, the emetic incidence decreased from 100 to 89 percent, but the frequency and latency were not altered significantly.

  9. Integrating histology and MRI in the first digital brain of common squirrel monkey, Saimiri sciureus.

    PubMed

    Sun, Peizhen; Parvathaneni, Prasanna; Schilling, Kurt G; Gao, Yurui; Janve, Vaibhav; Anderson, Adam; Landman, Bennett A

    2015-03-17

    This effort is a continuation of development of a digital brain atlas of the common squirrel monkey, Saimiri sciureus, a New World monkey with functional and microstructural organization of central nervous system similar to that of humans. Here, we present the integration of histology with multi-modal magnetic resonance imaging (MRI) atlas constructed from the brain of an adult female squirrel monkey. The central concept of this work is to use block face photography to establish an intermediate common space in coordinate system which preserves the high resolution in-plane resolution of histology while enabling 3-D correspondence with MRI. In vivo MRI acquisitions include high resolution T2 structural imaging (300 µm isotropic) and low resolution diffusion tensor imaging (600 um isotropic). Ex vivo MRI acquisitions include high resolution T2 structural imaging and high resolution diffusion tensor imaging (both 300 µm isotropic). Cortical regions were manually annotated on the co-registered volumes based on published histological sections in-plane. We describe mapping of histology and MRI based data of the common squirrel monkey and construction of a viewing tool that enable online viewing of these datasets. The previously descried atlas MRI is used for its deformation to provide accurate conformation to the MRI, thus adding information at the histological level to the MRI volume. This paper presents the mapping of single 2D image slice in block face as a proof of concept and this can be extended to map the atlas space in 3D coordinate system as part of the future work and can be loaded to an XNAT system for further use.

  10. Food availability and animal space use both determine cache density of Eurasian red squirrels.

    PubMed

    Rong, Ke; Yang, Hui; Ma, Jianzhang; Zong, Cheng; Cai, Tijiu

    2013-01-01

    Scatter hoarders are not able to defend their caches. A longer hoarding distance combined with lower cache density can reduce cache losses but increase the costs of hoarding and retrieving. Scatter hoarders arrange their cache density to achieve an optimal balance between hoarding costs and main cache losses. We conducted systematic cache sampling investigations to estimate the effects of food availability on cache patterns of Eurasian red squirrels (Sciurus vulgaris). This study was conducted over a five-year period at two sample plots in a Korean pine (Pinus koraiensis)-dominated forest with contrasting seed production patterns. During these investigations, the locations of nest trees were treated as indicators of squirrel space use to explore how space use affected cache pattern. The squirrels selectively hoarded heavier pine seeds farther away from seed-bearing trees. The heaviest seeds were placed in caches around nest trees regardless of the nest tree location, and this placement was not in response to decreased food availability. The cache density declined with the hoarding distance. Cache density was lower at sites with lower seed production and during poor seed years. During seed mast years, the cache density around nest trees was higher and invariant. The pine seeds were dispersed over a larger distance when seed availability was lower. Our results suggest that 1) animal space use is an important factor that affects food hoarding distance and associated cache densities, 2) animals employ different hoarding strategies based on food availability, and 3) seed dispersal outside the original stand is stimulated in poor seed years.

  11. Time-course of CSF histamine in the wake-consolidated squirrel monkey

    PubMed Central

    Zeitzer, Jamie M.; Kodama, Tohru; Buckmaster, Christine L.; Honda, Yoshiko; Lyons, David M.; Nishino, Seiji; Mignot, Emmanuel

    2011-01-01

    SUMMARY Central nervous system (CNS) histamine is low in individuals with narcolepsy, a disease characterized by severe fragmentation of both sleep and wake. We have developed a primate model, the squirrel monkey, with which we can examine the role of the CNS in the wake-consolidation process as these primates are day-active, have consolidated wake and sleep, and have cerebrospinal fluid (CSF) that is readily accessible. Using this model and three distinct protocols, we herein report on the role of CNS histamine in the wake consolidation process. CSF histamine has a robust daily rhythm, with a mean of 24.9 ± 3.29 pg·mL−1, amplitude of 31.7 ± 6.46 pg·mL−1 and a peak at 17:49 ± 70.3 min (lights on 07:00–19:00). These levels are not significantly affected by increases (up to 161±40.4% of baseline) or decreases (up to 17.2±2.50% of baseline) in locomotion. In direct contrast to the effects of sleep deprivation in non-wake consolidating mammals, in whom CSF histamine increases, pharmacologically-induced sleep (γ-hydroxybutyrate) and wake (modafinil) have no direct effects on CSF histamine concentrations. These data indicate that the time-course of histamine in CSF in the wake-consolidated squirrel monkey is robust against variation in activity and sleep and wake promoting pharmacological compounds, and may indicate that histamine physiology plays a role in wake-consolidation such as present in the squirrel monkey and humans. PMID:21910776

  12. Investigation of anti-motion sickness drugs in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Cheung, B. S.; Money, K. E.; Kohl, R. L.; Kinter, L. B.

    1992-01-01

    Early attempts to develop an animal model for anti-motion sickness drugs, using dogs and cats; were unsuccessful. Dogs did not show a beneficial effect of scopolamine (probably the best single anti-motion sickness drug for humans thus far) and the findings in cats were not definitive. The authors have developed an animal model using the squirrel monkey (Saimiri sciureus) of the Bolivian phenotype. Unrestrained monkeys in a small lucite cage were tested in an apparatus that induces motion sickness by combining vertical oscillation and horizontal rotation in a visually unrestricted laboratory environment. Signs of motion sickness were scored using a rating scale. Ten susceptible monkeys (weighing 800-1000 g) were given a total of five tests each, to establish the baseline susceptibility level. Based on the anticholinergic activity of scopolamine, the sensitivity of squirrel monkey to scopolamine was investigated, and the appropriate dose of scopolamine for this species was determined. Then various anti-motion sickness preparations were administered in subsequent tests: 100 ug scopolamine per monkey; 140 ug dexedrine; 50 ug scopolamine plus 70 ug dexedrine; 100 ug scopolamine plus 140 ug dexedrine; 3 mg promethazine; 3 mg promethazine plus 3 mg ephedrine. All these preparations were significantly effective in preventing motion sickness in the monkeys. Ephedrine, by itself, which is marginally effective in humans, was ineffective in the monkeys at the doses tried (0.3-6.0 mg). The squirrel monkey appears to be a good animal model for antimotion sickness drugs. Peripherally acting antihistamines such as astemizole and terfenadine were found to be ineffective, whereas flunarizine, and an arginine vasopressin V1 antagonist, showed significant activity in preventing motion sickness.

  13. Living on the edge: Space use of Eurasian red squirrels in marginal high-elevation habitat

    NASA Astrophysics Data System (ADS)

    Romeo, Claudia; Wauters, Lucas A.; Preatoni, Damiano; Tosi, Guido; Martinoli, Adriano

    2010-11-01

    In marginal habitats located at the edge of a species' range, environmental conditions are frequently extreme and individuals may be subject to different selective pressures compared to central populations. These so-called edge or marginal populations tend to have lower densities and reproductive rates than populations located in more suitable habitats, but little is known about local adaptations in spacing behavior. We studied space use and social organization in a population of Eurasian red squirrels ( Sciurus vulgaris) in a high-elevation marginal habitat of dwarf mountain pine ( Pinus mugo) and compared it with spacing patterns in high-quality Scots pine ( Pinus sylvestris) forest at lower-elevation. Home ranges and core areas were larger in the marginal habitat. In both habitats, males used larger home ranges than females, but sex differences in core area size were significant only in the edge population. Patterns of core area overlap were similar in both habitats with intra-sexual territoriality among adult females and higher degrees of inter-sexual overlap, typical for the species throughout its range. However, low densities in the edge population resulted in higher female by males overlap in spring-summer, suggesting males increased home ranges and core areas during mating season to augment access to estrus females. Thus, in the marginal habitat, with low food abundance and low population densities, linked with extreme winter conditions, squirrels, especially males, used large home ranges. Finally, squirrels responded more strongly to variation in food availability (inverse relation between home range size and seed abundance), and even to fluctuations in density (inverse relation between core area size and density of animals of the same sex), in the marginal than in the high-quality habitat, suggesting high behavioral plasticity to respond to the ecological constraints in marginal habitats.

  14. Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels

    PubMed Central

    Rong, Ke; Yang, Hui; Ma, Jianzhang; Zong, Cheng; Cai, Tijiu

    2013-01-01

    Scatter hoarders are not able to defend their caches. A longer hoarding distance combined with lower cache density can reduce cache losses but increase the costs of hoarding and retrieving. Scatter hoarders arrange their cache density to achieve an optimal balance between hoarding costs and main cache losses. We conducted systematic cache sampling investigations to estimate the effects of food availability on cache patterns of Eurasian red squirrels (Sciurus vulgaris). This study was conducted over a five-year period at two sample plots in a Korean pine (Pinus koraiensis)-dominated forest with contrasting seed production patterns. During these investigations, the locations of nest trees were treated as indicators of squirrel space use to explore how space use affected cache pattern. The squirrels selectively hoarded heavier pine seeds farther away from seed-bearing trees. The heaviest seeds were placed in caches around nest trees regardless of the nest tree location, and this placement was not in response to decreased food availability. The cache density declined with the hoarding distance. Cache density was lower at sites with lower seed production and during poor seed years. During seed mast years, the cache density around nest trees was higher and invariant. The pine seeds were dispersed over a larger distance when seed availability was lower. Our results suggest that 1) animal space use is an important factor that affects food hoarding distance and associated cache densities, 2) animals employ different hoarding strategies based on food availability, and 3) seed dispersal outside the original stand is stimulated in poor seed years. PMID:24265833

  15. Mapping of enkephalins and adrenocorticotropic hormone in the squirrel monkey brainstem.

    PubMed

    Duque-Díaz, Ewing; Díaz-Cabiale, Zaida; Narváez, José Angel; Coveñas, Rafael

    2017-03-01

    An immunocytochemical technique has been used to study for the first time the distribution of fibers and cell bodies containing leucine-enkephalin (leu-enk), methionine-enkephalin (met-enk) or adrenocorticotropic hormone (ACTH) in the whole brainstem of the squirrel monkey Saimiri sciureus. Cell bodies containing leu-enk or met-enk were found in the superior colliculus and the formatio reticularis tegmenti mesencephali, respectively. No immunoreactive cell bodies containing ACTH were observed. Leu-enk-immunoreactive fibers were observed in 40 brainstem nuclei/tracts/regions, fibers containing met-enk were found in 38 brainstem nuclei/tracts/regions and fibers containing ACTH were found in 26 nuclei/tracts/regions. In the latter case, the density of immunoreactive fibers was always low. A high/moderate density of leu-enk- or met-enk-immunoreactive fibers were found in 18 and 16 brainstem nuclei/tracts/regions, respectively. The distribution of immunoreactive fibers containing leu-enk or met-enk was quite similar, with both leu-enk and met-enk observed in 82.5 % of the squirrel monkey brainstem nuclei/tracts/regions. This relationship is less marked for met-enk and ACTH (60.5 %) and even lower for leu-enk and ACTH (52.5 %). In 42.5 % of the nuclei/tracts/regions of the squirrel monkey brainstem (colliculus superior, substantia grisea centralis, nucleus interpeduncularis, nucleus tractus spinalis nervi trigemini, nucleus tractus solitarii, nucleus parabrachialis, formatio reticularis, substantia nigra), we observed fibers containing all three neuropeptides. The widespread distribution reported here suggests that enkephalins and ACTH can be involved in several physiological functions. The distribution of the immunoreactive fibers reported here is quite similar to that previously reported for enkephalins and ACTH in Macaca species and humans.

  16. Integrating histology and MRI in the first digital brain of common squirrel monkey, Saimiri sciureus

    NASA Astrophysics Data System (ADS)

    Sun, Peizhen; Parvathaneni, Prasanna; Schilling, Kurt G.; Gao, Yurui; Janve, Vaibhav; Anderson, Adam; Landman, Bennett A.

    2015-03-01

    This effort is a continuation of development of a digital brain atlas of the common squirrel monkey, Saimiri sciureus, a New World monkey with functional and microstructural organization of central nervous system similar to that of humans. Here, we present the integration of histology with multi-modal magnetic resonance imaging (MRI) atlas constructed from the brain of an adult female squirrel monkey. The central concept of this work is to use block face photography to establish an intermediate common space in coordinate system which preserves the high resolution in-plane resolution of histology while enabling 3-D correspondence with MRI. In vivo MRI acquisitions include high resolution T2 structural imaging (300 μm isotropic) and low resolution diffusion tensor imaging (600 um isotropic). Ex vivo MRI acquisitions include high resolution T2 structural imaging and high resolution diffusion tensor imaging (both 300 μm isotropic). Cortical regions were manually annotated on the co-registered volumes based on published histological sections in-plane. We describe mapping of histology and MRI based data of the common squirrel monkey and construction of a viewing tool that enable online viewing of these datasets. The previously descried atlas MRI is used for its deformation to provide accurate conformation to the MRI, thus adding information at the histological level to the MRI volume. This paper presents the mapping of single 2D image slice in block face as a proof of concept and this can be extended to map the atlas space in 3D coordinate system as part of the future work and can be loaded to an XNAT system for further use.

  17. Influence of exposure to a prolonged hyperdynamic field on body temperature in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Fuller, C. A.

    1985-01-01

    The effect of gravitational loading on the regulation of body temperature is examined. Five adult male squirrel monkeys were exposed to a 2-G environment twice for 48 hours, once beginning in the middle of their light cycle and the second time in the middle of their dark cycle. It is observed that a reduction in body temperature occurs during the light cycle phase and at night there is an insignificant change in body temperature. The rhythmic characteristics of the light and dark cycles are analyzed. The data reveal that the body temperature in animals at 2 G is influenced more during the active phase of the animals 24-hour cycle.

  18. Anatomy and Disorders of the Oral Cavity of Rat-like and Squirrel-like Rodents.

    PubMed

    Mancinelli, Elisabetta; Capello, Vittorio

    2016-09-01

    The order Rodentia comprises more than 2000 species divided into 3 groups based on anatomic and functional differences of the masseter muscle. Myomorph and sciuromorph species have elodont incisors and anelodont cheek teeth, unlike hystrichomorph species which have full anelodont dentition. Diseases of incisors and cheek teeth of rat-like and squirrel-like rodents result in a wide variety of symptoms and clinical signs. Appropriate diagnostic testing and imaging techniques are required to obtain a definitive diagnosis, formulate a prognosis, and develop a treatment plan. A thorough review of elodontoma, odontoma, and pseudo-odontoma is provided, including treatment of pseudo-odontomas in prairie dogs.

  19. Effect of physical exercise prelabyrinthectomy on locomotor balance compensation in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Igarashi, M.; Ohashi, K.; Yoshihara, T.; MacDonald, S.

    1989-01-01

    This study examines the effectiveness of physical exercise, during a prepathology state, on locomotor balance compensation after subsequent unilateral labyrinthectomy in squirrel monkeys. An experimental group underwent 3 hr. of daily running exercise on a treadmill for 3 mo. prior to the surgery, whereas a control group was not exercised. Postoperatively, the locomotor balance function of both groups was tested for 3 mo. There was no significant difference in gait deviation counts in the acute phase of compensation. However, in the chronic compensation maintenance phase, the number of gait deviation counts was fewer in the exercise group, which showed significantly better performance stability.

  20. A detailed analysis of the erythropoietic control system in the human, squirrel, monkey, rat and mouse

    NASA Technical Reports Server (NTRS)

    Nordheim, A. W.

    1985-01-01

    The erythropoiesis modeling performed in support of the Body Fluid and Blood Volume Regulation tasks is described. The mathematical formulation of the species independent model, the solutions to the steady state and dynamic versions of the model, and the individual species specific models for the human, squirrel monkey, rat and mouse are outlined. A detailed sensitivity analysis of the species independent model response to parameter changes and how those responses change from species to species is presented. The species to species response to a series of simulated stresses directly related to blood volume regulation during space flight is analyzed.

  1. An Invasive Mammal (the Gray Squirrel, Sciurus carolinensis) Commonly Hosts Diverse and Atypical Genotypes of the Zoonotic Pathogen Borrelia burgdorferi Sensu Lato.

    PubMed

    Millins, Caroline; Magierecka, Agnieszka; Gilbert, Lucy; Edoff, Alissa; Brereton, Amelia; Kilbride, Elizabeth; Denwood, Matt; Birtles, Richard; Biek, Roman

    2015-07-01

    Invasive vertebrate species can act as hosts for endemic pathogens and may alter pathogen community composition and dynamics. For the zoonotic pathogen Borrelia burgdorferi sensu lato, the agent of Lyme borreliosis, recent work shows invasive rodent species can be of high epidemiological importance and may support host-specific strains. This study examined the role of gray squirrels (Sciurus carolinensis) (n = 679), an invasive species in the United Kingdom, as B. burgdorferi sensu lato hosts. We found that gray squirrels were frequently infested with Ixodes ricinus, the main vector of B. burgdorferi sensu lato in the United Kingdom, and 11.9% were infected with B. burgdorferi sensu lato. All four genospecies that occur in the United Kingdom were detected in gray squirrels, and unexpectedly, the bird-associated genospecies Borrelia garinii was most common. The second most frequent infection was with Borrelia afzelii. Genotyping of B. garinii and B. afzelii produced no evidence for strains associated with gray squirrels. Generalized linear mixed models (GLMM) identified tick infestation and date of capture as significant factors associated with B. burgdorferi sensu lato infection in gray squirrels, with infection elevated in early summer in squirrels infested with ticks. Invasive gray squirrels appear to become infected with locally circulating strains of B. burgdorferi sensu lato, and further studies are required to determine their role in community disease dynamics. Our findings highlight the fact that the role of introduced host species in B. burgdorferi sensu lato epidemiology can be highly variable and thus difficult to predict.

  2. Community ecology and disease risk: lizards, squirrels, and the Lyme disease spirochete in California, USA.

    PubMed

    Salkeld, Daniel J; Lane, Robert S

    2010-01-01

    Vector-borne zoonotic diseases are often maintained in complex transmission cycles involving multiple vertebrate hosts and their arthropod vectors. In the state of California, U.S.A., the spirochete Borrelia burgdorferi, which causes Lyme disease, is transmitted between vertebrate hosts by the western black-legged tick, Ixodes pacificus. Several mammalian species serve as reservoir hosts of the spirochete, but levels of tick infestation, reservoir competence, and Borrelia-infection prevalence vary widely among such hosts. Here, we model the host (lizards, Peromyscus mice, Californian meadow voles, dusky-footed wood rats, and western gray squirrels), vector, and pathogen community of oak woodlands in northwestern California to determine the relative importance of different tick hosts. Observed infection prevalence of B. burgdorferi in host-seeking I. pacificus nymphs was 1.8-5.3%, and our host-community model estimated an infection prevalence of 1.6-2.2%. The western gray squirrel (Sciurus griseus) was the only source of infected nymphs. Lizards, which are refractory to Borrelia infection, are important in feeding subadult ticks but reduce disease risk (nymphal infection prevalence). Species identity is therefore critical in understanding and determining the local disease ecology.

  3. Vestibular afferent responses to linear accelerations in the alert squirrel monkey

    NASA Technical Reports Server (NTRS)

    Somps, Christopher J.; Schor, Robert H.; Tomko, David L.

    1994-01-01

    The spontaneous activity of 40 otolith afferents and 44 canal afferents was recorded in 4 alert, intact squirrel monkeys. Polarization vectors and response properties of otolith afferents were determined during static re-orientations relative to gravity and during Earth-horizontal, sinusoidal, linear oscillations. Canal afferents were tested for sensitivity to linear accelerations. For regular otolith afferents, a significant correlation between upright discharge rate and sensitivity to dynamic acceleration in the horizontal plane was observed. This correlation was not present in irregular units. The sensitivity of otolith afferents to both static tilts and dynamic linear acceleration was much greater in irregularly discharging units than in regularly discharging units. The spontaneous activity and static and dynamic response properties of regularly discharging otolith afferents were similar to those reported in barbiturate-anesthetized squirrel monkeys. Irregular afferents also had similar dynamic response properties when compared to anesthetized monkeys. However, this sample of irregular afferents in alert animals had higher resting discharge rates and greater sensitivity to static tilts. The majority of otolith polarization vectors were oriented near the horizontal in the plane of the utricular maculae; however, directions of maximum sensitivity were different during dynamic and static testing. Canal afferents were not sensitive to static tilts or linear oscillations of the head.

  4. Squirrel monkeys (Saimiri sciureus) infected with the agent of bovine spongiform encephalopathy develop tau pathology.

    PubMed

    Piccardo, P; Cervenak, J; Yakovleva, O; Gregori, L; Pomeroy, K; Cook, A; Muhammad, F S; Seuberlich, T; Cervenakova, L; Asher, D M

    2012-07-01

    Squirrel monkeys (Saimiri sciureus) were infected experimentally with the agent of classical bovine spongiform encephalopathy (BSE). Two to four years later, six of the monkeys developed alterations in interactive behaviour and cognition and other neurological signs typical of transmissible spongiform encephalopathy (TSE). At necropsy examination, the brains from all of the monkeys showed pathological changes similar to those described in variant Creutzfeldt-Jakob disease (vCJD) of man, except that the squirrel monkey brains contained no PrP-amyloid plaques typical of that disease. Constant neuropathological features included spongiform degeneration, gliosis, deposition of abnormal prion protein (PrP(TSE)) and many deposits of abnormally phosphorylated tau protein (p-Tau) in several areas of the cerebrum and cerebellum. Western blots showed large amounts of proteinase K-resistant prion protein in the central nervous system. The striking absence of PrP plaques (prominent in brains of cynomolgus macaques [Macaca fascicularis] with experimentally-induced BSE and vCJD and in human patients with vCJD) reinforces the conclusion that the host plays a major role in determining the neuropathology of TSEs. Results of this study suggest that p-Tau, found in the brains of all BSE-infected monkeys, might play a role in the pathogenesis of TSEs. Whether p-Tau contributes to development of disease or appears as a secondary change late in the course of illness remains to be determined.

  5. Mapping and monitoring Mt. Graham Red Squirrel habitat with GIS and thematic mapper imagery

    USGS Publications Warehouse

    Hatten, James R.; Koprowski, John L.; Sanderson, H. Reed; Koprowski, John L.

    2009-01-01

    To estimate the Mt. Graham red squirrel (MGRS) population, personnel visit a proportion of middens each year to determine their occupancy (Snow in this vol.). The method results in very tight confidence intervals (high precision), but the accuracy of the population estimate is dependent upon knowing where all the middens are located. I hypothesized that there might be areas outside the survey boundary that contained Mt. Graham red squirrel middens, but the ruggedness of the Pinaleno Mountains made mountain-wide surveys difficult. Therefore, I started exploring development of a spatially explicit (geographic information system [GIS]-based) habitat model in 1998 that could identify MGRS habitat remotely with satellite imagery and a GIS. A GIS-based model would also allow us to assess changes in MGRS habitat between two time periods because Landsat passes over the same location every 16 days, imaging the earth in 185 km swaths (Aronoff 1989). Specifically, the objectives of this analysis were to (1) develop a pattern recognition model for MGRS habitat, (2) map potential (predicted/modeled) MGRS habitat, (3) identify changes in potential MGRS habitat between 1993 and 2003, and (4) evaluate the current location of the MGRS survey boundary.

  6. Recovery of the vomiting reflex following area postrema ablation in squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Elfar, S.; Brizzee, Kenneth R.; Fox, Robert A.; Corcoran, Meryl Lee; Daunton, Nancy G.; Coleman, J.

    1991-01-01

    The role of the area postrema (AP) in motion-induced emesis was re-assessed recently in several different species. In a few of these studies, the role of the AP in motion-induced conditioned taste aversion (CTA) was also addressed. The purpose was to extend this comparative study to the squirrel monkey, to evaluate further the role of AP in vomiting, and to investigate the dynamics of the recovery process. The AP was ablated bilaterally in 7 motion-susceptible squirrel monkeys which previously had been characterized in terms of their responses to various motion sickness-inducing stimuli. After recovery from surgery all animals were tested at 30-day intervals for a period of 11 months to determine the effects of AP ablations on susceptibility to the same sickness-inducing conditions. In addition, the effectiveness of motion in preducing CTA was evaluated. All pre-ablation motion tests involved stimulation for 30 min., while post-lesion tests were 60 min., in duration. All animals showed significant increases in latencies to vomiting after AP ablations. However, the latencies tended to decrease with time after ablation. All but one animal vomited on at least one of the 10 motion tests occurring after ablation of AP. In addition, CTA was produced by motion used in the conditioning sessions. These results suggest that structures other than AP, and processes other that those mediated through AP, may play an important role in motion-induced emesis.

  7. Purification and properties of squirrel monkey (Saimiri sciureus) corticosteroid binding globulins

    SciTech Connect

    Kuhn, R.W.; Weber, C.V.; Siiteri, P.K.

    1988-04-05

    Corticosteroid binding globulin (CBG), a serum glycoprotein which binds glucocorticoids and progestins with high affinity, is widely distributed throughout the animal world. Although its charge and size characteristics have largely been conserved across species, the authors found the behavior of CBG in squirrel monkey (Saimiri sciureus) serum during fractionation by polyacrylamide gel electrophoresis or Sephadex chromatography was consistent with a molecule about twice the size of that found in most species. To more fully understand the basis for this difference, they purified the protein by sequential affinity and DEAE-Sepharose chromatographies. The final product was obtained in greater than 60% yield and was found to migrate as a single homogeneous band when examined by electrophoresis. The steroid binding specificity of the purified protein was identical with that of the protein in the starting serum. In contrast to the single protein band observed following electrophoresis under normal conditions, separations in the presence of sodium dodecyl sulfate (SDS) resolved the pure protein into two bands: one at 54,000 daltons and one at 57,000 daltons. Unlike other species, squirrel monkey CBG exists as a dimer in its native state. Antibodies were generated against the purified material and tested for cross-reactivity against the sera from other species by both radioimmunodiffusion and radioimmunoassay techniques. Only serum from titi monkeys was observed to cross-react when examined by radioimmunoassay. Taken together, the results suggest that New World monkey CBG's are distinct from those of other species in both size and immunologic characteristics.

  8. Visual method for evaluating the state of sexual development in male grey squirrels (Sciurus carolinensis).

    PubMed

    Ferryman, Mark; Mayle, Brenda A; Morgan, Geoff W

    2006-01-01

    Stages of sexual development in grey squirrels were classified by scoring the presence of periscrotal hair and staining, as well as the position, size and colour of testes, to develop a visual breeding score (VBS). The VBS was a highly significant predictor of the presence and concentration of epididymal spermatozoa, which were produced from 12 months of age. Two classes of producers were identified: 'high' with spermatozoa levels > 10 x 10(6) mL(-1) and 'low' with spermatozoa levels < 10 x 10(6) mL(-1). Sperm motility was variable across all levels of productive males but was generally higher in the 'high' group, indicating that these were 'functional' males. Sexual regression was observed in two autumn periods. The VBS was less effective in determining states of regression and redevelopment; the confidence of classification improved when age class (adult or prepubertal) and date of capture was known. The use of the VBS to classify stages of sexual development in grey squirrels will improve selection of animals for studies of population biology and fertility control, and has potential application in captive breeding studies of rare Sciuridae species.

  9. Effects of restricted feeding schedules on circadian organization in squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Boulos, Z.; Frim, D. M.; Dewey, L. K.; Moore-Ede, M. C.

    1989-01-01

    Free running circadian rhythms of motor activity, food-motivated lever-pressing, and either drinking (N = 7) or body temperature (N = 3) were recorded from 10 squirrel monkeys maintained in constant illumination with unlimited access to food. Food availability was then restricted to a single unsignaled 3-hour interval each day. The feeding schedule failed to entrain the activity rhythms of 8 monkeys, which continued to free-run. Drinking was almost completely synchronized by the schedule, while body temperature showed a feeding-induced rise superimposed on a free-running rhythm. Nonreinforced lever-pressing showed both a free-running component and a 24-hour component that anticipated the time of feeding. At the termination of the schedule, all recorded variables showed free-running rhythms, but in 3 animals the initial phase of the postschedule rhythms was advanced by several hours, suggesting relative coordination. Of the remaining 2 animals, one exhibited stable entrainment of all 3 recorded rhythms, while the other appeared to entrain temporarily to the feeding schedule. These results indicate that restricted feeding schedules are only a weak zeitgeber for the circadian pacemaker generating free-running rhythms in the squirrel monkey. Such schedules, however, may entrain a separate circadian system responsible for the timing of food-anticipatory changes in behavior and physiology.

  10. Effect of Environmental Enrichment on Singly- and Group-Housed Squirrel Monkeys

    NASA Technical Reports Server (NTRS)

    Spring, Sarah E.; Clifford, James O.; Tomko, David L.; Hargens, Alan R. (Technical Monitor)

    1996-01-01

    Nonhuman primates display an interest in novel places, habituate to new situations, and spend most of their daily activity in the wild in large groups engaging in feeding behaviors. Captivity changes these behaviors, and disrupts normal social hierarchies. In captivity, animals may exhibit stereotypical behaviors which are thought to indicate decreased psychological well-being (PWB). If an animal's behaviors can be made to approach those seen in the wild, and stereotypical behaviors are minimal it is assumed that PWB is adequate. Environmental enrichment (EE) devices have been used to address the Animal Welfare Act's requirement that the PWB of captive nonhuman primates be considered. The purpose of the present study was to examine whether various EE devices improve the PWB of captive squirrel monkeys. The present study used behavioral observation to quantify the effectiveness of several EE devices in reducing stereotypical behaviors in squirrel monkeys housed singly or in groups. Results showed that the EE devices used did not affect the expression of normal or stereotypical behaviors, but that the type of housing did.

  11. Impact of Striped-Squirrel Nectar-Robbing Behaviour on Gender Fitness in Alpinia roxburghii Sweet (Zingiberaceae)

    PubMed Central

    Deng, Xiaobao; Mohandass, Dharmalingam; Katabuchi, Masatoshi; Hughes, Alice C.; Roubik, David W.

    2015-01-01

    Nectar-robbing has the potential to strongly affect male and female reproductive fitness of plants. One example of nectar theft is that shown by striped-squirrels (Tamiops swinhoei) on a number of ginger species, including Alpinia roxburghii and A. kwangsiensis (Zingiberaceae). In this study, we used a fluorescent dye as a pollen analogue, and measured fruit and seed output, to test the effect of squirrel nectar-robbing on A. roxburghii reproductive fitness. Pollen transfer between robbed and unrobbed flowers was assessed by comparing 60 randomly established plots containing robbed and unrobbed flowers. The frequency of squirrel robbing visits and broken styles were recorded from a number of flowers for five consecutive days. Two bee species (Bombus eximius and Apis cerana), were the primary pollinators, and their visitation frequency was recorded for six consecutive days. The results showed that fluorescent powder from unrobbed flowers was dispersed further, and to a greater number of flowers than that placed on robbed flowers. Additionally, robbing flowers caused significant damage to reproductive organs, resulting in lower fruit and seed sets in robbed than in unrobbed flowers and influencing both male and female fitness. The frequency of the primary pollinator visits (B. eximius) was significantly higher for unrobbed plants than for robbed plants. The present study clearly shows the negative impact of squirrel robbing on A. roxburghii male reproductive fitness and neutral impact on female reproductive fitness. PMID:26689684

  12. Effect of environmental enrichment devices on behaviors of single- and group-housed squirrel monkeys (Saimiri sciureus)

    NASA Technical Reports Server (NTRS)

    Spring, S. E.; Clifford, J. O.; Tomko, D. L.

    1997-01-01

    Squirrel monkeys display an interest in novel places, habituate to new situations, and spend most of their daily activity in the wild in large groups engaging in feeding behaviors over a broad area. Captivity limits these behaviors and consequently may disrupt normal social organizations. In captivity, squirrel monkeys may exhibit stereotypical behaviors that are believed to indicate decreased psychologic well-being. When a monkey's behavior can be made to approach that seen in the wild, and stereotypical behaviors are minimal, it is assumed that psychologic well-being is adequate. Environmental enrichment devices have been used to address the Animal Welfare Act requirement that psychologic well-being of captive nonhuman primates be considered. The purpose of the study reported here was to examine whether various environmental enrichment devices improve the psychologic well-being of captive squirrel monkeys. In the study, we used behavioral observation to quantify the effectiveness of several environmental enrichment devices for reducing stereotypical behaviors in squirrel monkeys housed alone or in groups. Analysis of our results revealed that the environmental enrichment devices did not affect the expression of normal or stereotypical behaviors, but that the type of housing did.

  13. Beach almond (Terminalia catappa, Combretaceae) seed production and predation by scarlet macaws (Ara macao) and variegated squirrels (Sciurus variegatoides).

    PubMed

    Henn, Jonathan J; McCoy, Michael B; Vaughan, Christopher S

    2014-09-01

    Knowledge of ecological impacts of exotic beach almond (Terminalia catappa) in the central Pacific of Costa Rica are little known, but studies have found this species to be a potentially important food source for endangered scarlet macaws (Ara macao). In this study, reproductive phenology and seed predation by variegated squirrels (Sciurus variegatoides) and scarlet macaws were measured during March and April 2011 on beaches of central Pacific coastal Costa Rica. Seed productivity and predation levels were quantified on a weekly basis for 111 beach almond trees to assess the importance of beach almond as a food source for scarlet macaws and the extent of resource partitioning between seed predators. Seed production of the trees was great (about 194 272 seeds) and approximately 67% of seeds were predated by seed predators. Macaws consumed an estimated 49% of seeds while squirrels consumed 18%. Additionally, evidence of resource partitioning between squirrels and macaws was found. Scarlet macaws preferred to feed on the northern side and edge of the canopy while squirrels preferred to feed on the southern and inside parts of the canopy. Both species ate most seeds on the ocean side of the tree. Despite the status of this tree as an exotic species, the beach almond appears to be an important resource for scarlet macaw population recovery. The resource produced by this tree should be taken into account as reforestation efforts continue in Costa Rica.

  14. Grounded theory.

    PubMed

    Harris, Tina

    2015-04-29

    Grounded theory is a popular research approach in health care and the social sciences. This article provides a description of grounded theory methodology and its key components, using examples from published studies to demonstrate practical application. It aims to demystify grounded theory for novice nurse researchers, by explaining what it is, when to use it, why they would want to use it and how to use it. It should enable nurse researchers to decide if grounded theory is an appropriate approach for their research, and to determine the quality of any grounded theory research they read.

  15. Segregating the Effects of Seed Traits and Common Ancestry of Hardwood Trees on Eastern Gray Squirrel Foraging Decisions

    PubMed Central

    Sundaram, Mekala; Willoughby, Janna R.; Lichti, Nathanael I.; Steele, Michael A.; Swihart, Robert K.

    2015-01-01

    The evolution of specific seed traits in scatter-hoarded tree species often has been attributed to granivore foraging behavior. However, the degree to which foraging investments and seed traits correlate with phylogenetic relationships among trees remains unexplored. We presented seeds of 23 different hardwood tree species (families Betulaceae, Fagaceae, Juglandaceae) to eastern gray squirrels (Sciurus carolinensis), and measured the time and distance travelled by squirrels that consumed or cached each seed. We estimated 11 physical and chemical seed traits for each species, and the phylogenetic relationships between the 23 hardwood trees. Variance partitioning revealed that considerable variation in foraging investment was attributable to seed traits alone (27–73%), and combined effects of seed traits and phylogeny of hardwood trees (5–55%). A phylogenetic PCA (pPCA) on seed traits and tree phylogeny resulted in 2 “global” axes of traits that were phylogenetically autocorrelated at the family and genus level and a third “local” axis in which traits were not phylogenetically autocorrelated. Collectively, these axes explained 30–76% of the variation in squirrel foraging investments. The first global pPCA axis, which produced large scores for seed species with thin shells, low lipid and high carbohydrate content, was negatively related to time to consume and cache seeds and travel distance to cache. The second global pPCA axis, which produced large scores for seeds with high protein, low tannin and low dormancy levels, was an important predictor of consumption time only. The local pPCA axis primarily reflected kernel mass. Although it explained only 12% of the variation in trait space and was not autocorrelated among phylogenetic clades, the local axis was related to all four squirrel foraging investments. Squirrel foraging behaviors are influenced by a combination of phylogenetically conserved and more evolutionarily labile seed traits that is

  16. First Report of the Human-Pathogenic Enterocytozoon bieneusi from Red-Bellied Tree Squirrels (Callosciurus erythraeus) in Sichuan, China

    PubMed Central

    Deng, Lei; Li, Wei; Yu, Xingming; Gong, Chao; Liu, Xuehan; Zhong, Zhijun; Xie, Na; Lei, Shuangshuang; Yu, Jianqiu; Fu, Hualin; Chen, Hongwei; Xu, Huailiang; Hu, Yanchun; Peng, Guangneng

    2016-01-01

    Enterocytozoon bieneusi is a common opportunistic pathogen causing diarrhea and enteric disease in a variety of animal hosts. Although it has been reported in many animals, there is no published information available on the occurrence of E. bieneusi in red-bellied tree squirrels. To understand the occurrence, genetic diversity, and zoonotic potential of E. bieneusi in red-bellied tree squirrels, 144 fecal specimens from Sichuan province, China, were examined by PCR amplification and sequencing of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene of E. bieneusi. The overall infection rate of E. bieneusi 16.7% (24/144) was observed in red-bellied tree squirrels. Altogether five genotypes of E. bieneusi were identified: three known genotypes D (n = 18), EbpC (n = 3), SC02 (n = 1) and two novel genotypes CE01, CE02 (one each). Multilocus sequence typing (MLST) analysis employing three microsatellite (MS1, MS3, MS7) and one minisatellite (MS4) revealed 16, 14, 7 and 14 positive specimens were successfully sequenced, and identified eight, three, three and two genotypes at four loci, respectively. In phylogenetic analysis, the three known genotypes D, EbpC, and SC02 were clustered into group 1 with zoonotic potential, and the two novel genotypes CE01 and CE02 were clustered into group 6. The present study firstly reported the occurrence of E. bieneusi in red-bellied tree squirrels in China, and the E. bieneusi genotypes D and EbpC were found in humans previously. These results indicate that red-bellied tree squirrels may play a potential role in the transmission of E. bieneusi to humans. PMID:27683278

  17. Pathologic findings in Western gray squirrels (Sciurus griseus) from a notoedric mange epidemic in the San Bernardino Mountains, California☆

    PubMed Central

    Stephenson, Nicole; Swift, Pam; Villepique, Jeffrey T.; Clifford, Deana L.; Nyaoke, Akinyi; De la Mora, Alfonso; Moore, Janet; Foley, Janet

    2013-01-01

    Notoedric mange, caused by the contagious, burrowing mite Notoedres centrifera, has been associated with several large-scale population declines of western gray squirrels (Sciurus griseus) and has been a significant obstacle to population recovery in Washington State where the species is listed as threatened. In 2009, residents and wildlife rehabilitators in the isolated San Bernardino Mountains of southern California reported a dramatic die-off of western gray squirrels, in what had been a previously dense and robust population. Individuals were observed suffering from abnormal neurologic behaviors (ataxia and obtundation) and severe skin disease. Full necropsy of five squirrels from the epidemic showed that all had moderate to severe infestation with mange mites and severe dermatitis characterized by hyperkeratosis, acanthosis, intralesional mites, intracorneal pustules and superficial bacteria. Mites from affected squirrels were evaluated by light and electron microscopy and identified as N. centrifera based on morphologic criteria. Additionally, the internal transcribed spacer-2 region of the mite was cloned, sequenced and accessioned in GenBank. The cause for the abnormal neurologic behavior was not confirmed on post-mortem examination. However, we hypothesize that mange can cause incoordination and obtundation as a result of malnutrition and dehydration, and intense pruritis may induce abnormal or erratic behavior that could be mistaken for neurologic signs. While we have characterized the severe impact this disease can have on individual animals, more work is needed to understand the impact on squirrel populations, particularly in view of the anecdotal reports of dramatic population declines that may take decades to recover. PMID:24533345

  18. Segregating the Effects of Seed Traits and Common Ancestry of Hardwood Trees on Eastern Gray Squirrel Foraging Decisions.

    PubMed

    Sundaram, Mekala; Willoughby, Janna R; Lichti, Nathanael I; Steele, Michael A; Swihart, Robert K

    2015-01-01

    The evolution of specific seed traits in scatter-hoarded tree species often has been attributed to granivore foraging behavior. However, the degree to which foraging investments and seed traits correlate with phylogenetic relationships among trees remains unexplored. We presented seeds of 23 different hardwood tree species (families Betulaceae, Fagaceae, Juglandaceae) to eastern gray squirrels (Sciurus carolinensis), and measured the time and distance travelled by squirrels that consumed or cached each seed. We estimated 11 physical and chemical seed traits for each species, and the phylogenetic relationships between the 23 hardwood trees. Variance partitioning revealed that considerable variation in foraging investment was attributable to seed traits alone (27-73%), and combined effects of seed traits and phylogeny of hardwood trees (5-55%). A phylogenetic PCA (pPCA) on seed traits and tree phylogeny resulted in 2 "global" axes of traits that were phylogenetically autocorrelated at the family and genus level and a third "local" axis in which traits were not phylogenetically autocorrelated. Collectively, these axes explained 30-76% of the variation in squirrel foraging investments. The first global pPCA axis, which produced large scores for seed species with thin shells, low lipid and high carbohydrate content, was negatively related to time to consume and cache seeds and travel distance to cache. The second global pPCA axis, which produced large scores for seeds with high protein, low tannin and low dormancy levels, was an important predictor of consumption time only. The local pPCA axis primarily reflected kernel mass. Although it explained only 12% of the variation in trait space and was not autocorrelated among phylogenetic clades, the local axis was related to all four squirrel foraging investments. Squirrel foraging behaviors are influenced by a combination of phylogenetically conserved and more evolutionarily labile seed traits that is consistent with a weak

  19. Predation of a squirrel monkey (Saimiri sciureus) by an Amazon tree boa (Corallus hortulanus): even small boids may be a potential threat to small-bodied platyrrhines.

    PubMed

    Ribeiro-Júnior, Marco Antônio; Ferrari, Stephen Francis; Lima, Janaina Reis Ferreira; da Silva, Claudia Regina; Lima, Jucivaldo Dias

    2016-07-01

    Predation has been suggested to play a major role in the evolution of primate ecology, although reports of predation events are very rare. Mammalian carnivores, raptors, and snakes are known predators of Neotropical primates, and most reported attacks by snakes are attributed to Boa constrictor (terrestrial boas). Here, we document the predation of a squirrel monkey (Saimiri sciureus) by an Amazon tree boa (Corallus hortulanus), the first record of the predation of a platyrrhine primate by this boid. The event was recorded during a nocturnal herpetological survey in the Piratuba Lake Biological Reserve, in the north-eastern Brazilian Amazon. The snake was encountered at 20:00 hours on the ground next to a stream, at the final stage of ingesting the monkey. The C. hortulanus specimen was 1620 mm in length (SVL) and weighed 650 g, while the S. sciureus was a young adult female weighing 600 g, 92 % of the body mass of the snake and the largest prey item known to have been ingested by a C. hortulanus. The evidence indicates that the predation event occurred at the end of the afternoon or early evening, and that, while capable of capturing an agile monkey like Saimiri, C. hortulanus may be limited to capturing small platyrrhines such as callitrichines.

  20. Molecular cloning of pituitary glycoprotein alpha-subunit and follicle stimulating hormone and chorionic gonadotropin beta-subunits from New World squirrel monkey and owl monkey.

    PubMed

    Scammell, Jonathan G; Funkhouser, Jane D; Moyer, Felricia S; Gibson, Susan V; Willis, Donna L

    2008-02-01

    The goal of this study was to characterize the gonadotropins expressed in pituitary glands of the New World squirrel monkey (Saimiri sp.) and owl monkey (Aotus sp.). The various subunits were amplified from total RNA from squirrel monkey and owl monkey pituitary glands by reverse transcription-polymerase chain reaction and the deduced amino acid sequences compared to those of other species. Mature squirrel monkey and owl monkey glycoprotein hormone alpha-polypeptides (96 amino acids in length) were determined to be 80% homologous to the human sequence. The sequences of mature beta subunits of follicle stimulating hormone (FSHbeta) from squirrel monkey and owl monkey (111 amino acids in length) are 92% homologous to human FSHbeta. New World primate glycoprotein hormone alpha-polypeptides and FSHbeta subunits showed conservation of all cysteine residues and consensus N-linked glycosylation sites. Attempts to amplify the beta-subunit of luteinizing hormone from squirrel monkey and owl monkey pituitary glands were unsuccessful. Rather, the beta-subunit of chorionic gonadotropin (CG) was amplified from pituitaries of both New World primates. Squirrel monkey and owl monkey CGbeta are 143 and 144 amino acids in length and 77% homologous with human CGbeta. The greatest divergence is in the C terminus, where all four sites for O-linked glycosylation in human CGbeta, responsible for delayed metabolic clearance, are predicted to be absent in New World primate CGbetas. It is likely that CG secreted from pituitary of New World primates exhibits a relatively short half-life compared to human CG.

  1. Hypothalamic gene expression underlying pre-hibernation satiety.

    PubMed

    Schwartz, C; Hampton, M; Andrews, M T

    2015-03-01

    Prior to hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) enter a hypophagic period where food consumption drops by an average of 55% in 3 weeks. This occurs naturally, while the ground squirrels are in constant environmental conditions and have free access to food. Importantly, this transition occurs before exposure to hibernation conditions (5°C and constant darkness), so the ground squirrels are still maintaining a moderate level of activity. In this study, we used the Illumina HiSeq 2000 system to sequence the hypothalamic transcriptomes of ground squirrels before and after the autumn feeding transition to examine the genes underlying this extreme change in feeding behavior. The hypothalamus was chosen because it is known to play a role in the control and regulation of food intake and satiety. Overall, our analysis identified 143 genes that are significantly differentially expressed between the two groups. Specifically, we found five genes associated with feeding behavior and obesity (VGF, TRH, LEPR, ADIPOR2, IRS2) that are all upregulated during the hypophagic period, after the feeding transition has occurred. We also found that serum leptin significantly increases in the hypophagic group. Several of the genes associated with the natural autumnal feeding decline in 13-lined ground squirrels show parallels to signaling pathways known to be disrupted in human metabolic diseases, like obesity and diabetes. In addition, many other genes were identified that could be important for the control of food consumption in other animals, including humans.

  2. Temperature and behavioral responses of squirrel monkeys to 2Gz acceleration

    NASA Technical Reports Server (NTRS)

    Fuller, C. A.; Tremor, J.; Connolly, J. P.; Williams, B. A.

    1982-01-01

    This study examines the responses of squirrel monkeys to acute +2Gz exposure. Body temperature responses of loosely restrained animals were recorded via a thermistor in the colon. Behavioral responses were recorded by video monitoring. After baseline recording at 1G, monkeys were exposed to 2G for 60 min. The body temperature started to fall within 10 min of the onset of centrifugation and declined an average of 1.4 C in 60 min. This is in contrast to a stable body temperature during the control period. Further, after a few minutes at 2G, the animals became drowsy and appeared to fall asleep. During the control period, however, they were alert and continually shifting their gaze about the cage. Thus, primates are susceptible to hypergravic fields in the +Gz orientation. The depression in primate body temperature was consistent and significant. Further, the observed drowsiness in this study has significant ramifications regarding alertness and performance in man.

  3. Molecular characterization of major histocompatibility complex class 1 (MHC-I) from squirrel monkeys (Saimiri sciureus).

    PubMed

    Pascalis, Hervé; Heraud, Jean-Michel; Fendel, Rolf; Lavergne, Anne; Kazanji, Mirdad

    2003-12-01

    Little is known about the major histocompatibility complex (MHC) class 1 in squirrel monkeys ( Saimiri sciureus). We cloned, sequenced and characterized two alleles and the cDNA of the coding region of MHC class 1 in these New World monkeys. Phylogenetic analyses showed that these sequences are related to HLA class 1 genes ( HLA-A and HLA-G). The structure and organization of one of the two identified clones was similar to that of a class 1 MHC gene ( HLA-A2). All the exon/intron splice acceptor/donor sites are conserved and their locations correspond to the HLA-A2 gene. The sequences of the newly described cDNAs reveal that they code for the characteristic class 1 MHC proteins, with all the features thought necessary for cell surface expression. Typical sequences for the leader peptide, alpha(1), alpha(2), alpha(3), transmembrane and cytoplasmic domains were found.

  4. Finite element modelling of squirrel, guinea pig and rat skulls: using geometric morphometrics to assess sensitivity.

    PubMed

    Cox, P G; Fagan, M J; Rayfield, E J; Jeffery, N

    2011-12-01

    Rodents are defined by a uniquely specialized dentition and a highly complex arrangement of jaw-closing muscles. Finite element analysis (FEA) is an ideal technique to investigate the biomechanical implications of these specializations, but it is essential to understand fully the degree of influence of the different input parameters of the FE model to have confidence in the model's predictions. This study evaluates the sensitivity of FE models of rodent crania to elastic properties of the materials, loading direction, and the location and orientation of the models' constraints. Three FE models were constructed of squirrel, guinea pig and rat skulls. Each was loaded to simulate biting on the incisors, and the first and the third molars, with the angle of the incisal bite varied over a range of 45°. The Young's moduli of the bone and teeth components were varied between limits defined by findings from our own and previously published tests of material properties. Geometric morphometrics (GMM) was used to analyse the resulting skull deformations. Bone stiffness was found to have the strongest influence on the results in all three rodents, followed by bite position, and then bite angle and muscle orientation. Tooth material properties were shown to have little effect on the deformation of the skull. The effect of bite position varied between species, with the mesiodistal position of the biting tooth being most important in squirrels and guinea pigs, whereas bilateral vs. unilateral biting had the greatest influence in rats. A GMM analysis of isolated incisor deformations showed that, for all rodents, bite angle is the most important parameter, followed by elastic properties of the tooth. The results here elucidate which input parameters are most important when defining the FE models, but also provide interesting glimpses of the biomechanical differences between the three skulls, which will be fully explored in future publications.

  5. Finite element modelling of squirrel, guinea pig and rat skulls: using geometric morphometrics to assess sensitivity

    PubMed Central

    Cox, P G; Fagan, M J; Rayfield, E J; Jeffery, N

    2011-01-01

    Rodents are defined by a uniquely specialized dentition and a highly complex arrangement of jaw-closing muscles. Finite element analysis (FEA) is an ideal technique to investigate the biomechanical implications of these specializations, but it is essential to understand fully the degree of influence of the different input parameters of the FE model to have confidence in the model's predictions. This study evaluates the sensitivity of FE models of rodent crania to elastic properties of the materials, loading direction, and the location and orientation of the models’ constraints. Three FE models were constructed of squirrel, guinea pig and rat skulls. Each was loaded to simulate biting on the incisors, and the first and the third molars, with the angle of the incisal bite varied over a range of 45°. The Young's moduli of the bone and teeth components were varied between limits defined by findings from our own and previously published tests of material properties. Geometric morphometrics (GMM) was used to analyse the resulting skull deformations. Bone stiffness was found to have the strongest influence on the results in all three rodents, followed by bite position, and then bite angle and muscle orientation. Tooth material properties were shown to have little effect on the deformation of the skull. The effect of bite position varied between species, with the mesiodistal position of the biting tooth being most important in squirrels and guinea pigs, whereas bilateral vs. unilateral biting had the greatest influence in rats. A GMM analysis of isolated incisor deformations showed that, for all rodents, bite angle is the most important parameter, followed by elastic properties of the tooth. The results here elucidate which input parameters are most important when defining the FE models, but also provide interesting glimpses of the biomechanical differences between the three skulls, which will be fully explored in future publications. PMID:21974720

  6. Increasing length of wakefulness and modulation of hypocretin-1 in the wake-consolidated squirrel monkey.

    PubMed

    Zeitzer, Jamie M; Buckmaster, Christine L; Lyons, David M; Mignot, Emmanuel

    2007-10-01

    The neuropeptides hypocretins (orexins), the loss of which results in the sleep disorder narcolepsy, are hypothesized to be involved in the consolidation of wakefulness and have been proposed to be part of the circadian-driven alertness signal. To elucidate the role of hypocretins in the consolidation of human wakefulness we examined the effect of wake extension on hypocretin-1 in squirrel monkeys, primates that consolidate wakefulness during the daytime as do humans. Wake was extended up to 7 h with hypocretin-1, cortisol, ghrelin, leptin, locomotion, and feeding, all being assayed. Hypocretin-1 (P < 0.01), cortisol (P < 0.001), and locomotion (P < 0.005) all increased with sleep deprivation, while ghrelin (P = 0.79) and leptin (P = 1.00) did not change with sleep deprivation. Using cross-correlation and multivariate modeling of these potential covariates along with homeostatic pressure (a measure of time awake/asleep), we found that time of day and homeostatic pressure together explained 44% of the variance in the hypocretin-1 data (P < 0.001), while cortisol did not significantly contribute to the overall hypocretin-1 variance. Locomotion during the daytime, but not during the nighttime, helped explain < 5% of the hypocretin-1 variance (P < 0.05). These data are consistent with earlier evidence indicating that in the squirrel monkey hypocretin-1 is mainly regulated by circadian inputs and homeostatic sleep pressure. Concomitants of wakefulness that affect hypocretin-1 in polyphasic species, such as locomotion, food intake, and food deprivation, likely have a more minor role in monophasic species, such as humans.

  7. sup 14 C-2-deoxyglucose uptake in the ground squirrel brain during entrance to and arousal from hibernation

    SciTech Connect

    Kilduff, T.S.; Miller, J.D.; Radeke, C.M.; Sharp, F.R.; Heller, H.C. )

    1990-07-01

    Neuronal activity underlying various phases of the mammalian hibernation cycle was investigated using the {sup 14}C-2-deoxyglucose (2DG) method. Relative 2DG uptake (R2DGU) values were computed for 96 brain regions across 7 phases of the hibernation cycle: euthermia, 3 body temperature (Tb) intervals during entrance into hibernation, stable deep hibernation, and 2 Tb intervals during arousal from hibernation. Multivariate statistical techniques were employed to identify objectively groups of brain regions whose R2DGU values showed a similar pattern across all phases of hibernation. Factor analysis revealed that most of the variability in R2DGU values for the 96 brain regions across the entire cycle could be accounted for by 3 principal factors. These factors could accurately discriminate the various phases of hibernation on the basis of the R2DGU values alone. Three hypothalamic and 3 cortical regions were identified as possibly mediating the entrance into hibernation because they underwent a change in R2DGU early in entrance into hibernation and loaded strongly on one of the principal factors. Another 4 hypothalamic regions were similarly identified as possibly causally involved in the arousal from hibernation. These results, coupled with characteristic changes in ordinal rank of the 96 brain regions in each phase of hibernation, support the concept that mammalian hibernation is an active, integrated orchestration of neurophysiological events rather than a state entered through a passive process.

  8. Molecular cloning of the unintegrated squirrel monkey retrovirus genome: organization and distribution of related sequences in primate DNAs.

    PubMed Central

    Chiu, I M; Andersen, P R; Aaronson, S A; Tronick, S R

    1983-01-01

    The closed circular form of the endogenous squirrel monkey type D retrovirus (SMRV) was molecularly cloned in a bacteriophage vector. The restriction map of the biologically active clone was determined and found to be identical to that of the parental SMRV linear DNA except for the deletion of one long terminal repeat. Restriction enzyme analysis and Southern blotting indicated that the SMRV long terminal repeat was approximately 300 base pairs long. The SMRV restriction map was oriented to the viral RNA by using a gene-specific probe from baboon endogenous virus. Restriction enzyme digests of a variety of vertebrate DNAs were analyzed for DNA sequence homology with SMRV by using the cloned SMRV genome as a probe. Consistent with earlier studies, multiple copies of SMRV were detected in squirrel monkey DNA. Related fragments were also detected in the DNAs from other primate species, including humans. Images PMID:6312076

  9. Ontogeny of joint mechanics in squirrel monkeys (Saimiri boliviensis): functional implications for mammalian limb growth and locomotor development

    PubMed Central

    Young, Jesse W.

    2009-01-01

    Summary Juvenile animals must often compete against adults for common resources, keep pace during group travel and evade common predators, despite reduced body size and an immature musculoskeletal system. Previous morphometric studies of a diverse array of mammals, including jack rabbits, cats and capuchin monkeys, have identified growth-related changes in anatomy, such as negative allometry of limb muscle mechanical advantage, which should theoretically permit young mammals to overcome such ontogenetic limits on performance. However, it is important to evaluate the potential impact of such `compensatory' growth trajectories within the context of developmental changes in locomotor behavior. I used standard kinematic and kinetic techniques to investigate the ontogenetic scaling of joint postures, substrate reaction forces, joint load arm lengths and external joint moments in an ontogenetic sample of squirrel monkeys (Saimiri boliviensis). Results indicated that young squirrel monkeys were frequently able to limit forelimb and hind limb joint loading via a combination of changes in limb posture and limb force distribution, potentially compensating for limited muscularity at younger ages. These results complement previous morphometric studies and suggest that immature mammals may utilize a combination of behavioral and anatomical mechanisms to mitigate ontogenetic limits on locomotor performance. However, ontogenetic changes in joint posture, not limb length per se, explained most of the variation in load arm lengths and joint loading in growing squirrel monkeys, indicating the importance of incorporating both anatomical and performance measures when studying the ontogeny of limb joint mechanics. PMID:19411552

  10. A comparison of positive reinforcement training techniques in owl and squirrel monkeys: time required to train to reliability.

    PubMed

    Rogge, Jessica; Sherenco, Katrina; Malling, Rachel; Thiele, Erica; Lambeth, Susan; Schapiro, Steve; Williams, Lawrence

    2013-01-01

    Positive reinforcement training (PRT) techniques enhance the psychological well being of nonhuman primates by increasing the animal's control over his or her environment and desensitizing the animal to stressful stimuli. However, the literature on PRT in neotropical primates is limited. Here PRT data from owl monkeys and squirrel monkeys are presented, including the length of time to train subjects to target, present hand, and present foot, important responses that can be used to aid in health inspection and treatment. A high percentage of the squirrel and owl monkeys were successfully trained on target and present hand. Present foot, a less natural response, was harder to train and maintain. Although squirrel monkeys did learn to target significantly faster than owl monkeys, the 2 genera did not differ on time to train on subsequent behavior. These data demonstrate that although owl monkeys may require slightly more time to acclimate to a PRT program, it is still possible to establish a PRT program with neotropical primates, and once animals have been introduced to the program, they can learn new responses in a relatively few short sessions.

  11. Impacts of climate change and renewable energy development on habitat of an endemic squirrel, Xerospermophilus mohavensis, in the Mojave Desert, USA

    USGS Publications Warehouse

    Inman, Richard D.; Esque, Todd; Nussear, Kenneth E.; Leitner, Philip; Matocq, Marjorie D.; Weisberg, Peter J.; Dilts, Thomas E.

    2016-01-01

    Predicting changes in species distributions under a changing climate is becoming widespread with the use of species distribution models (SDMs). The resulting predictions of future potential habitat can be cast in light of planned land use changes, such as urban expansion and energy development to identify areas with potential conflict. However, SDMs rarely incorporate an understanding of dispersal capacity, and therefore assume unlimited dispersal in potential range shifts under uncertain climate futures. We use SDMs to predict future distributions of the Mojave ground squirrel, Xerospermophilus mohavensis Merriam, and incorporate partial dispersal models informed by field data on juvenile dispersal to assess projected impact of climate change and energy development on future distributions of X. mohavensis. Our models predict loss of extant habitat, but also concurrent gains of new habitat under two scenarios of future climate change. Under the B1 emissions scenario- a storyline describing a convergent world with emphasis on curbing greenhouse gas emissions- our models predicted losses of up to 64% of extant habitat by 2080, while under the increased greenhouse gas emissions of the A2 scenario, we suggest losses of 56%. New potential habitat may become available to X. mohavensis, thereby offsetting as much as 6330 km2 (50%) of the current habitat lost. Habitat lost due to planned energy development was marginal compared to habitat lost from changing climates, but disproportionately affected current habitat. Future areas of overlap in potential habitat between the two climate change scenarios are identified and discussed in context of proposed energy development.

  12. Simultaneous measurement of extracellular dopamine and dopamine transporter occupancy by cocaine analogs in squirrel monkeys.

    PubMed

    Kimmel, Heather L; Nye, Jonathon A; Voll, Ronald; Mun, Jiyoung; Stehouwer, Jeffrey; Goodman, Mark M; Votaw, John R; Carroll, F I; Howell, Leonard L

    2012-06-01

    Several classes of drugs bind to the dopamine transporter (DAT) with high affinity, but some are weaker positive reinforcers than cocaine, suggesting that affinity for and occupancy of the DAT is not the only determinant of a drug's reinforcing effectiveness. Other factors such as the rate of onset have been positively and strongly correlated with the reinforcing effects of DAT inhibitors in nonhuman primates. In the current studies, we examined the effects of acute systemic administration of cocaine and three cocaine analogs (RTI-150, RTI-177, and RTI-366) on binding to DAT in squirrel monkey brain using positron emission tomography (PET) neuroimaging. During the PET scan, we also measured drug effects on dopamine (DA) levels in the caudate using in vivo microdialysis. In general, our results suggest a lack of concordance between drug occupancy at DAT and changes in DA levels. These studies also indicate that acute cocaine administration decreases the availability of plasma membrane DAT for binding, even after cocaine is no longer blocking DA uptake as evidence by a return to basal DA levels.

  13. Cooling and freezing of sperm from captive, free-living and endangered squirrel monkey species.

    PubMed

    Oliveira, Karol G; Santos, Regiane R; Leão, Danuza L; Brito, Adriel B; Lima, Julianne S; Sampaio, Wlaísa V; Domingues, Sheyla F S

    2016-06-01

    Germoplasm banking is an important tool for the preservation of genetic material from Neotropical primates in captivity, and from free living species, especially the endangered ones like Saimiri vanzolinii (Black-headed squirrel monkey), a primate with a low incidence area (870 km(2) of floodplains) in the southern part of the Mamirauá Sustainable Development Reserve, Brazil. Therefore, in the present study we aimed to develop a sperm cryopreservation protocol comparing sperm cooling in presence (T1) and absence (T2) of egg yolk, and to test freezing protocols to preserve semen from captive (Saimiri collinsi), and free-living (Saimiri vanzolinii, Saimiri cassiquiarensis and Saimiri macrodon) New World primates. Cooling preserved sperm of S. collinsi in all evaluated microscopic parameters, except for sperm motility. No differences were observed among the treatments, indicating that semen of this species can be cooled without egg yolk. Freezing did not affect sperm quality of S. collinsi, except plasma membrane integrity that was negatively affected. Generally, a good maintenance rate was observed between cooling and thawing of semen for the four species, showing the positive translational application of protocols from S. collinsi to the free-living species. Developed freezing protocol proved to be useful for sperm cryopreservation of S. collinsi and in field conditions.

  14. Lifetime selection on heritable life-history traits in a natural population of red squirrels.

    PubMed

    Réale, D; Berteaux, D; McAdam, A G; Boutin, S

    2003-10-01

    Despite their importance in evolutionary biology, heritability and the strength of natural selection have rarely been estimated in wild populations of iteroparous species or have usually been limited to one particular event during an organism's lifetime. Using an animal-model restricted maximum likelihood and phenotypic selection models, we estimated quantitative genetic parameters and the strength of lifetime selection on parturition date and litter size at birth in a natural population of North American red squirrels, Tamiasciurus hudsonicus. Litter size at birth and parturition date had low heritabilities (h2 = 0.15 and 0.16, respectively). We considered potential effects of temporal environmental covariances between phenotypes and fitness and of spatial environmental heterogeneity in estimates of selection. Selection favored early breeders and females that produced litter sizes close to the population average. Stabilizing selection on litter size at birth may occur because of a trade-off between number of offspring produced per litter and offspring survival or a trade-off between a female's fecundity and her future reproductive success and survival.

  15. Sleep-wake responses of squirrel monkeys exposed to hyperdynamic environments

    NASA Technical Reports Server (NTRS)

    Fuller, C. A.

    1983-01-01

    This study examines the sleep responses of primates to acute 3 Gz environments. To investigate this question, loosely-restrained squirrel monkeys were exposed to 70 minutes of 3 Gz during the day. The animals' behavioral state was polygraphically monitored (EEG, EMG, EOG) along with video and deep body temperature. During the control period, animals exhibited slow wave sleep (SWS) napping behavior. SWS occurred during approximately 20 percent of the control period. Body temperature was maintained at 38.7 C. At 3 Gz, SWS was inhibited for 5 minutes, after which SWS occurred at levels 50 percent lower than in the control period. During the post-centrifugation period, SWS was elevated above the control (50 percent) and hyperdynamic (100 percent) levels. Body temperature was depressed 1.5 C when the animals were at 3 Gz. Thus, hyperdynamic environments are capable of modifying primate sleep behavior, at least as a result of acute exposure. Further, the increased arousal in the hyperdynamic environment is correlated with a lower body temperature. This negative correlation differs from the normal positive correlation of arousal and body temperature.

  16. Light masking of circadian rhythms of heat production, heat loss, and body temperature in squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Robinson, E. L.; Fuller, C. A.

    1999-01-01

    Whole body heat production (HP) and heat loss (HL) were examined to determine their relative contributions to light masking of the circadian rhythm in body temperature (Tb). Squirrel monkey metabolism (n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of body temperature and activity. Feeding was also measured. Responses to an entraining light-dark (LD) cycle (LD 12:12) and a masking LD cycle (LD 2:2) were compared. HP and HL contributed to both the daily rhythm and the masking changes in Tb. All variables showed phase-dependent masking responses. Masking transients at L or D transitions were generally greater during subjective day; however, L masking resulted in sustained elevation of Tb, HP, and HL during subjective night. Parallel, apparently compensatory, changes of HL and HP suggest action by both the circadian timing system and light masking on Tb set point. Furthermore, transient HL increases during subjective night suggest that gain change may supplement set point regulation of Tb.

  17. The geographic selection mosaic for ponderosa pine and crossbills: a tale of two squirrels.

    PubMed

    Parchman, Thomas L; Benkman, Craig W

    2008-02-01

    Recent research demonstrates how the occurrence of a preemptive competitor (Tamiasciurus) gives rise to a geographic mosaic of coevolution for crossbills (Loxia) and conifers. We extend these studies by examining ponderosa pine (Pinus ponderosa), which produces more variable annual seed crops than the conifers in previous studies and often cooccurs with tree squirrels in the genus Sciurus that are less specialized than Tamiasciurus on conifer seed. We found no evidence of seed defenses evolving in response to selection exerted by S. aberti, which was apparently overwhelmed by selection resulting from inner bark feeding that caused many developing cones to be destroyed. In the absence of S. aberti, defenses directed at crossbills increased, favoring larger-billed crossbills and causing stronger reciprocal selection between crossbills and ponderosa pine. However, crossbill nomadism in response to cone crop fluctuations prevents localized reciprocal adaptation by crossbills. In contrast, evolution in response to S. griseus has incidentally defended cones against crossbills, limiting the geographic range of the interaction between crossbills and ponderosa pine. Our results suggest that annual resource variation does not prevent competitors from shaping selection mosaics, although such fluctuations likely prevent fine-scale geographic differentiation in predators that are nomadic in response to resource variability.

  18. Bony labyrinth morphometry indicates locomotor adaptations in the squirrel-related clade (Rodentia, Mammalia).

    PubMed

    Pfaff, Cathrin; Martin, Thomas; Ruf, Irina

    2015-06-22

    The semicircular canals (SCs) of the inner ear detect angular acceleration and are located in the bony labyrinth of the petrosal bone. Based on high-resolution computed tomography, we created a size-independent database of the bony labyrinth of 50 mammalian species especially rodents of the squirrel-related clade comprising taxa with fossorial, arboreal and gliding adaptations. Our sampling also includes gliding marsupials, actively flying bats, the arboreal tree shrew and subterranean species. The morphometric anatomy of the SCs was correlated to the locomotion mode. Even if the phylogenetic signal cannot entirely be excluded, the main significance for functional morphological studies has been found in the diameter of the SCs, whereas the radius of curvature is of minor interest. Additionally, we found clear differences in the bias angle of the canals between subterranean and gliding taxa, but also between sciurids and glirids. The sensitivity of the inner ear correlates with the locomotion mode, with a higher sensitivity of the SCs in fossorial species than in flying taxa. We conclude that the inner ear of flying and gliding mammals is less sensitive due to the large information flow into this sense organ during locomotion.

  19. Interspecific interactions between primates, birds, bats, and squirrels may affect community composition on Borneo.

    PubMed

    Beaudrot, Lydia; Struebig, Matthew J; Meijaard, Erik; van Balen, Sebastianus; Husson, Simon; Young, Carson F; Marshall, Andrew J

    2013-02-01

    For several decades, primatologists have been interested in understanding how sympatric primate species are able to coexist. Most of our understanding of primate community ecology derives from the assumption that these animals interact predominantly with other primates. In this study, we investigate to what extent multiple community assembly hypotheses consistent with this assumption are supported when tested with communities of primates in isolation versus with communities of primates, birds, bats, and squirrels together. We focus on vertebrate communities on the island of Borneo, where we examine the determinants of presence or absence of species, and how these communities are structured. We test for checkerboard distributions, guild proportionality, and Fox's assembly rule for favored states, and predict that statistical signals reflecting interactions between ecologically similar species will be stronger when nonprimate taxa are included in analyses. We found strong support for checkerboard distributions in several communities, particularly when taxonomic groups were combined, and after controlling for habitat effects. We found evidence of guild proportionality in some communities, but did not find significant support for Fox's assembly rule in any of the communities examined. These results demonstrate the presence of vertebrate community structure that is ecologically determined rather than randomly generated, which is a finding consistent with the interpretation that interactions within and between these taxonomic groups may have shaped species composition in these communities. This research highlights the importance of considering the broader vertebrate communities with which primates co-occur, and so we urge primatologists to explicitly consider nonprimate taxa in the study of primate ecology.

  20. Neuronal Control of Mammalian Vocalization, with Special Reference to the Squirrel Monkey

    NASA Astrophysics Data System (ADS)

    Jürgens, Uwe

    Squirrel monkey vocalization can be considered as a suitable model for the study in humans of the neurobiological basis of nonverbal emotional vocal utterances, such as laughing, crying, and groaning. Evaluation of electrical and chemical brain stimulation data, lesioning studies, single-neurone recordings, and neuroanatomical tracing work leads to the following conclusions: The periaqueductal gray and laterally bordering tegmentum of the midbrain represent a crucial area for the production of vocalization. This area collects the various vocalization-triggering stimuli, such as auditory, visual, and somatosensory input from diverse sensory-processing structures, motivation-controlling input from some limbic structures, and volitional impulses from the anterior cingulate cortex. Destruction of this area causes mutism. It is still under dispute whether the periaqueductal region harbors the vocal pattern generator or merely couples vocalization-triggering information to motor-coordinating structures further downward in the brainstem. The periaqueductal region is connected with the phonatory motoneuron pools indirectly via one or several interneurons. The nucleus retroambiguus represents a crucial relay station for the laryngeal and expiratory component of vocalization. The articulatory component reaches the orofacial motoneuron pools via the parvocellular reticular formation. Essential proprioceptive feedback from the larynx and lungs enter the vocal-controlling network via the solitary tract nucleus.

  1. Bony labyrinth morphometry indicates locomotor adaptations in the squirrel-related clade (Rodentia, Mammalia)

    PubMed Central

    Pfaff, Cathrin; Martin, Thomas; Ruf, Irina

    2015-01-01

    The semicircular canals (SCs) of the inner ear detect angular acceleration and are located in the bony labyrinth of the petrosal bone. Based on high-resolution computed tomography, we created a size-independent database of the bony labyrinth of 50 mammalian species especially rodents of the squirrel-related clade comprising taxa with fossorial, arboreal and gliding adaptations. Our sampling also includes gliding marsupials, actively flying bats, the arboreal tree shrew and subterranean species. The morphometric anatomy of the SCs was correlated to the locomotion mode. Even if the phylogenetic signal cannot entirely be excluded, the main significance for functional morphological studies has been found in the diameter of the SCs, whereas the radius of curvature is of minor interest. Additionally, we found clear differences in the bias angle of the canals between subterranean and gliding taxa, but also between sciurids and glirids. The sensitivity of the inner ear correlates with the locomotion mode, with a higher sensitivity of the SCs in fossorial species than in flying taxa. We conclude that the inner ear of flying and gliding mammals is less sensitive due to the large information flow into this sense organ during locomotion. PMID:26019162

  2. Histological and mucin histochemical study of the small intestine of the Persian squirrel (Sciurus anomalus).

    PubMed

    Tootian, Zahra; Sadeghinezhad, Javad; Sheibani, Mohammad Taghi; Fazelipour, Simin; De Sordi, Nadia; Chiocchetti, Roberto

    2013-01-01

    This article describes the histological and mucin histochemical properties of the small intestine of the Persian squirrel (Sciurus anomalus). This species is widely distributed in the Middle East and can be found as a companion animal. The histological studies revealed that the plicae circulares were not visible in the tunica mucosa. The maximum height and width of the villi were observed in the duodenum, which then decreased toward the ileum. The muscularis mucosa was scattered, whereas the tunica submucosa was composed of dense connective tissue. The lymphatic nodules were seen in the submucosa of the distal part of the jejunum and ileum, and Brunner's glands were embedded in the initial portion of the duodenum. The tunica muscularis was significantly thicker in the ileum, and the circular muscle layer was thicker than the longitudinal muscle layer throughout the entire length of the small intestine. The mucin histochemistry, which was examined using the periodic acid-Schiff (PAS) and alcian blue (AB) (pH 1.0 and 2.5) and also PAS-AB (pH 2.5) and aldehyde fuchsin-AB (pH 2.5) techniques coupled with methylation and saponification reaction for some sections, showed that the small intestine mucous content included both carboxylated and sulfated acidic mucins with few neutral mucins. The results of this study contribute to the knowledge of the histological and histochemical characteristics of the gastrointestinal tracts of exotic mammals and provide data for comparison with other mammals.

  3. Some relations between classically conditioned aggression and conditioned suppression in squirrel monkeys.

    PubMed Central

    Hake, D F; Campbell, R L

    1980-01-01

    During three experiments with squirrel monkeys, stimulus and shock pairings were given in the presence of a bite tube. Experiments 1 and 2 used a conditioned-suppression procedure in which bar pressing was reinforced with food. A transparent shield prevented biting of the bar. When the stimulus was paired with shock, bar pressing decreased (conditioned suppression) and tube biting increased during the stimulus (classically conditioned aggression). When the bite tube was removed on alternate sessions in Experiment 2, there was more suppression when the tube was present, thus suggesting that biting competed with bar pressing. However, this simple competing-response interpretation was complicated by the findings of Experiment 3 where, with naive monkeys, bar pressing was never reinforced with food, yet bar pressing was induced during the stimulus and was highest when the bite tube was absent. The fact that stimulus-induced bar pressing developed inciated that bar pressing in conditioned-suppression procedures, suppressed or not, may be maintained by two types of control--the food reinforcer and induced CS control. The higher rate of induced bar pressing during the stimulus with the bite tube absent confounds a simple competing response interpretation of conditioned suppression. It suggests that shock-induced responses during conditioned suppression could be both contributing to and competing with responding maintained by food, with the net effect depending on specific but ill-defined features of the situation. PMID:7190996

  4. Hydrogeology and simulation of flow between the alluvial and bedrock aquifers in the upper Black Squirrel Creek basin, El Paso County, Colorado

    USGS Publications Warehouse

    Watts, K.R.

    1995-01-01

    Anticipated increases in pumping from the bedrock aquifers in El Paso County potentially could affect the direction and rate of flow between the alluvial and bedrock aquifers and lower water levels in the overlying alluvial aquifer. The alluvial aquifer underlies about 90 square miles in the upper Black Squirrel Creek Basin of eastern El Paso County. The alluvial aquifer consists of unconsolidated alluvial deposits that unconformably overlie siltstones, sandstones, and conglomerate (bedrock aquifers) and claystone, shale, and coal (bedrock confining units) of the Denver Basin. The bedrock aquifers (Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers) are separated by confining units (upper and lower Denver and the Laramie confining units) and overlie a relatively thick and impermeable Pierre confining unit. The Pierre confining unit is assumed to be a no-flow boundary at the base of the alluvial/ bedrock aquifer system. During 1949-90, substantial water-level declines, as large as 50 feet, in the alluvial aquifer resulted from withdrawals from the alluvial aquifer for irrigation and municipal supplies. Average recharge to the alluvial aquifer from infiltration of precipitation and surface water was an estimated 11.97 cubic feet per second and from the underlying bedrock aquifers was an estimated 0.87 cubic foot per second. Water-level data from eight bedrock observation wells and eight nearby alluvial wells indicate that, locally, the alluvial and bedrock aquifers probably are hydraulically connected and that the alluvial aquifer in the upper Black Squirrel Creek Basin receives recharge from the Denver and Arapahoe aquifers but-locally recharges the Laramie-Fox Hills aquifer. Subsurface-temperature profiles were evaluated as a means of estimating specific discharge across the bedrock surface (the base of the alluvial aquifer). However, assumptions of the analytical method were not met by field conditions and, thus, analyses of subsurface-temperature profiles

  5. Immunolocalization of Growth, Inhibitory, and Proliferative Factors Involved in Initial Ovarian Folliculogenesis From Adult Common Squirrel Monkey (Saimiri collinsi)

    PubMed Central

    Brito, A. B.; Domingues, S. F. S.; Santos, R. R.; Amorim, C. A.

    2015-01-01

    We performed an immunohistochemical (IHC) study to determine the follicular expression of growth differentiation factor 9 (GDF-9), anti-Müllerian hormone (AMH), Kit Ligand (KL), and c-Kit in squirrel monkey ovary. Ovarian tissue fragments from 4 squirrel monkeys were collected by laparotomy and processed for classical histology and IHC. Additionally, follicle development was assessed by Ki67 immunostaining to evaluate proliferative status of granulosa cells. A total of 4025 follicles were examined (1475 for classical histology and 2550 for immunohistochemistry). More than 80% of the evaluated follicles were morphologically normal. The GDF-9 protein was detectable in oocyte cytoplasm from primordial (100%), primary (99.1%), and secondary (100%) follicles. The AMH was not expressed in primordial follicles but just in few primary follicles (13.8%). On the other hand, it was highly expressed in granulosa cells from secondary follicles (67.9%). c-Kit, KL receptor, was found in the oolemma of primordial (100%), primary (100%), and secondary (100%) follicles. The KL expression was observed in oocytes and granulosa cells from primordial (94.9%), primary (91.6%) and secondary follicles (100%). Ki67 immunostaining was observed in granulosa cells from primary (5.7%) and secondary (54.8%) follicles but not in primordial follicles. In conclusion, we described the localization of GDF-9, KL, c-Kit, and Ki67 proteins and confirmed the presence of AMH protein in preantral follicles from squirrel monkey. Our results offer contribution for understanding of folliculogenesis in neotropical nonhuman primates. Moreover, these markers can be used to assess follicular viability and functionality after cryopreservation, transplantation, or in vitro culture of ovarian tissue. PMID:24784715

  6. Role of otolith endorgans in the genesis of vestibular-visual conflict sickness (pitch) in the squirrel monkey (First report)

    NASA Technical Reports Server (NTRS)

    Igarashi, Makoto; Himi, Tetsuo; Kulecz, Walter B.; Kobayashi, Kazutoyo

    1987-01-01

    The effects of ablation of the macula utriculi and macula sacculi on vestibular-visual conflict emesis in squirrel monkeys are investigated. An optokinetic drum and a turntable were used for the direction conflict experiment. A significant difference between the preoperative condition and postunilateral and postbilateral utriculo-sacculectomy conditions is observed. It is detected that after unilateral sacculectomy the conflict sickness decreases and no emesis occurs; however, 4.5 months after sacculectomy, the animals regain their conflict sickness. The data reveal that macular afferents are important in the genesis of sensory conflict emesis and two submodalities may be needed to cause conflict sickness onset.

  7. Sexual dimorphism in the squirrel monkey, Saimiri sciureus (Linnaeus, 1758) and Saimiri ustus (I. Geoffroy, 1844) (Primates, Cebidae).

    PubMed

    Goldschmidt, B; Mota-Marinho, A; Araújo-Lopes, C; Brück-Gonçalves, M A; Matos-Fasano, D; Ribeiro-Andrade, M C; Ferreira-Nascimento, L W; Simmer-Bravin, J; Monnerat-Nogueira, D

    2009-02-01

    Causes and implications of sexual dimorphism have been studied in several different primates using a variety of morphological characters such as body weight, canine length, coat color and ornamentation. Here we describe a peculiar coat color characteristic in the squirrel monkey that is present only in adult females over five years old and which increases with age. Neither males nor young animals manifest this phenomenon, which is characterized by a spot of black hairs located anteriorly to the external ear (pinna). This characteristic could be used to discriminate adult females of Saimiri sciureus in the wild without the need of capture techniques.

  8. Effects of modified chromophores on the spectral sensitivity of salamander, squirrel and macaque cones.

    PubMed

    Makino, C L; Kraft, T W; Mathies, R A; Lugtenburg, J; Miley, M E; van der Steen, R; Baylor, D A

    1990-05-01

    1. Chemically modified retinal chromophores were used to investigate the mechanisms that produce the characteristic spectral absorptions of cone pigments. Spectral sensitivities of single cones from the salamander, squirrel and macaque retina were determined by electrical recording. The chromophore was then replaced by bleaching the pigment and regenerating it with a retinal analogue. 2. Exposing a bleached cone to 9-cis-retinal for a brief period (less than 20 min) caused its flash sensitivity to recover to about 0.2 of the pre-bleach value. Similar exposure to a locked 6-s-cis, 9-cis analogue gave a recovery to about 0.03 of the pre-bleach value. 3. Unlike the flash sensitivity, the saturating photocurrent amplitude often recovered completely after bleaching and regenerating the pigment. 4. When the 3-dehydroretinal chromophore in the salamander long-wavelength-sensitive (red) cone was replaced with 11-cis-retinal, shortening the conjugated chain in the chromophore, the spectral sensitivity underwent a blue shift of 67 nm. 5. Pigments containing the planar-locked 6-s-cis.9-cis-retinal analogue absorbed at substantially longer wavelength than those containing unmodified 9-cis-retinal. The opsin shift, a measure of the protein's ability to modify the chromophore's absorption was larger for the locked analogue than for 9-cis-retinal. This suggests that the native chromophore assumes a twisted 6-s-cis conformation in these pigments. 6. The spectral sensitivities of red and green macaque cones containing 9-cis-retinal or planar-locked 6-s-cis.9-cis-retinal retained the 30 nm separation characteristic of the native pigments. This suggests that the different absorptions of of the 6-7 carbon bond in the retinal chromophore.

  9. Effects of southern flying squirrels Glaucomys volans on red-cockaded woodpecker Picoides borealis reproductive success

    USGS Publications Warehouse

    Laves, K.S.; Loeb, S.C.

    1999-01-01

    Anecdotal data gathered from many populations suggest that southern flying squirrel (SFS, Glaucomys volans) use of the endangered red-cockaded woodpecker's (RCW, Picoides borealis) nest and roost cavities may negatively affect RCW populations. We conducted a controlled experiment to determine the effects of SFSs on RCW reproductive success. During the 1994 and 1995 breeding seasons, SFSs were removed from 30 RCW clusters and 32 clusters served as controls. SFSs were the most frequently encountered occupants of RCW cavities and used 20-33% of RCW cavities in control and treatment clusters over both years. Treatment groups produced significantly more successful nests (??? 1 fledgling) than control groups in 1994. In 1995 however, there was no difference in the number of successful nests. In both years, RCW groups nesting in treatment clusters produced significantly more fledglings than groups in control clusters in each of four experimental areas, averaging approximately 0.7 additional fledglings per nesting group. Loss of entire clutches or broods, possibly as a result of predation or abandonment, was a major factor limiting reproduction in control groups in 1994. In contrast, differences in partial brood loss appeared to be the cause of differential fledging success in 1995 Usurpation of RCW roost cavities by SFSs may have placed greater energetic demands on RCWs for cavity defence or thermoregulation, thus reducing energy available for reproduction. Our results show that SFS use of RCW cavities during the breeding season has a significant impact on RCWs and that management of RCW populations should include activities that either minimize SFS populations in RCW clusters or limit access of SFSs to RCW cavities.

  10. Modeling the vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1995-01-01

    Model simulations of the squirrel monkey vestibulo-ocular reflex (VOR) are presented for two motion paradigms: constant velocity eccentric rotation and roll tilt about a naso-occipital axis. The model represents the implementation of three hypotheses: the "internal model" hypothesis, the "gravito-inertial force (GIF) resolution" hypothesis, and the "compensatory VOR" hypothesis. The internal model hypothesis is based on the idea that the nervous system knows the dynamics of the sensory systems and implements this knowledge as an internal dynamic model. The GIF resolution hypothesis is based on the idea that the nervous system knows that gravity minus linear acceleration equals GIF and implements this knowledge by resolving the otolith measurement of GIF into central estimates of gravity and linear acceleration, such that the central estimate of gravity minus the central estimate of acceleration equals the otolith measurement of GIF. The compensatory VOR hypothesis is based on the idea that the VOR compensates for the central estimates of angular velocity and linear velocity, which sum in a near-linear manner. During constant velocity eccentric rotation, the model correctly predicts that: (1) the peak horizontal response is greater while "facing-motion" than with "back-to-motion"; (2) the axis of eye rotation shifts toward alignment with GIF; and (3) a continuous vertical response, slow phase downward, exists prior to deceleration. The model also correctly predicts that a torsional response during the roll rotation is the only velocity response observed during roll rotations about a naso-occipital axis. The success of this model in predicting the observed experimental responses suggests that the model captures the essence of the complex sensory interactions engendered by eccentric rotation and roll tilt.

  11. Differential adaptation of the linear and nonlinear components of the horizontal vestibuloocular reflex in squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Clendaniel, Richard A.; Lasker, David M.; Minor, Lloyd B.; Shelhamer, M. J. (Principal Investigator)

    2002-01-01

    Previous work in squirrel monkeys has demonstrated the presence of linear and nonlinear components to the horizontal vestibuloocular reflex (VOR) evoked by high-acceleration rotations. The nonlinear component is seen as a rise in gain with increasing velocity of rotation at frequencies more than 2 Hz (a velocity-dependent gain enhancement). We have shown that there are greater changes in the nonlinear than linear component of the response after spectacle-induced adaptation. The present study was conducted to determine if the two components of the response share a common adaptive process. The gain of the VOR, in the dark, to sinusoidal stimuli at 4 Hz (peak velocities: 20-150 degrees /s) and 10 Hz (peak velocities: 20 and 100 degrees /s) was measured pre- and postadaptation. Adaptation was induced over 4 h with x0.45 minimizing spectacles. Sum-of-sines stimuli were used to induce adaptation, and the parameters of the stimuli were adjusted to invoke only the linear or both linear and nonlinear components of the response. Preadaptation, there was a velocity-dependent gain enhancement at 4 and 10 Hz. In postadaptation with the paradigms that only recruited the linear component, there was a decrease in gain and a persistent velocity-dependent gain enhancement (indicating adaptation of only the linear component). After adaptation with the paradigm designed to recruit both the linear and nonlinear components, there was a decrease in gain and no velocity-dependent gain enhancement (indicating adaptation of both components). There were comparable changes in the response to steps of acceleration. We interpret these results to indicate that separate processes drive the adaptation of the linear and nonlinear components of the response.

  12. Predators, energetics and fitness drive neonatal reproductive failure in red squirrels.

    PubMed

    Studd, Emily K; Boutin, Stan; McAdam, Andrew G; Krebs, Charles J; Humphries, Murray M

    2015-01-01

    Neonatal reproductive failure should occur when energetic costs of parental investment outweigh fitness benefits. However, little is known about the drivers of neonatal reproductive failure in free-ranging species experiencing continuous natural variation in predator abundance and in the energetic and fitness costs and benefits associated with parental investment. Long-term comprehensive studies are required to better understand how biotic, abiotic and life-history conditions interact to drive occurrences of reproductive failure in the wild. Using 24 years (1987-2011) of reproductive data from a northern boreal population of North American red squirrels in south-western Yukon, we examined the effects of predator abundance, energetics (resource availability, ambient temperature and litter size) and fitness benefits (probability of overwinter juvenile survival and maternal age) on occurrences of neonatal reproductive failure (494/2670 reproductive attempts; 18·5%). Neonatal reproductive failure was driven by a combination of predator abundance, and the energetic and fitness costs and benefits of parental investment. The abundance of mustelids and maternal age was positively related to the occurrence of neonatal reproductive failure. High energy costs associated with a combination of low resource availability and cold ambient temperatures or large litters, corresponded to increased occurrences of neonatal reproductive failure. However, the strength of these relationships was influenced by variation in juvenile overwinter survival (i.e. fitness benefits). We provide evidence that predation pressure is an important driver of neonatal reproductive failure. In addition, we found a trade-off occurs between resource-dependent energetic and fitness costs and benefits of raising the current litter to independence.

  13. Effects of the Nanoparticle-Based Vaccine, SEL-068, on Nicotine Discrimination in Squirrel Monkeys

    PubMed Central

    Desai, Rajeev I; Bergman, Jack

    2015-01-01

    A key feature of addiction to nicotine likely resides in its ability to produce subjective effects that, in turn, may be reflected in its discriminative-stimulus properties. Vaccination against such effects of nicotine offers an intriguing therapeutic approach for smoking cessation, but a reliably effective and immunologically safe vaccine remains to be identified. Here we report on the ability of SEL-068, a nanoparticle-based vaccine that targets nicotine, to modify the discriminative-stimulus effects of nicotine in a primate species. Results indicate that squirrel monkeys vaccinated with SEL-068 failed to acquire 0.1 mg/kg nicotine discrimination but readily learned to discriminate 0.001 mg/kg of the nicotinic full agonist (+)-epibatidine ((+)-EPI). After (+)-EPI training, doses of nicotine ⩾0.32 mg/kg, which produced behaviorally adverse actions, still failed to substitute for the (+)-EPI training stimulus in immunized monkeys, whereas (+)-EPI and the partial agonist varenicline engendered, respectively, complete and partial substitution in all monkeys with potency comparable to their potency in non-immunized subjects. In other subjects, nicotine was trained as a discriminative-stimulus and then replaced by (+)-EPI. Subsequent vaccination with SEL-068 led to a threefold and long-lasting (>30 weeks) decrease in the potency of nicotine but not (+)-EPI or varenicline. Collectively, our results show that SEL-068 can block the development of nicotine discrimination and attenuate nicotine's effects in nicotine-experienced monkeys without altering the discriminative-stimulus properties of other nicotinic drugs. The difference in the vaccine's effects in naive and nicotine-experienced subjects provides important insight into the conditions under which immunotherapy may be effective in combating nicotine addiction. PMID:25742871

  14. Ground Water

    USGS Publications Warehouse

    ,

    1986-01-01

    Some water underlies the Earth's surface almost everywhere, beneath hills, mountains,plains, and deserts. It's not always accessible, or fresh enough for use without treatment, and it's sometimes difficult to locate or to measure and descri be. This water may occur close to the land surface, as in a marsh, or it may lie many hundreds of feet below the surface, as in some arid areas of the West. Water at very shallow depths might be just a few hours old ; at moderate depth, it may be 100 years old; and at great depth or after having flowed long distances from places of entry, water may be several thousands of years old . Water under the Earth's surface is called ground water.

  15. Big Cypress fox squirrel (Sciurus niger avicennia) ecology and habitat use in a cypress dome swamp-pine forest mosaic.

    PubMed

    Kellam, John O; Jansen, Deborah K; Johnson, Annette T; Arwood, Ralph W; Merrick, Melissa J; Koprowski, John L

    2016-01-20

    Forested wetlands are in decline, as are many species that are obligate residents. Big Cypress fox squirrels (BCFS; Sciurus niger avicennia) are a threatened endemic to wet pine and cypress forests in southwestern Florida. The region is characterized by development resulting in habitat loss, habitat fragmentation, and hydrological change that influence the quality of these wet forests. Through radiotelemetry and field observations, we examined the ecology and habitat use of BCFS in a natural cypress dome-pine forest mosaic. BCFS selected cypress domes for food and nests throughout the year. Cypress dome habitats were the only habitat type to be used more than available; however, the availability of nearby pine forest was also important. Home ranges were large relative to other tree squirrels, with male home ranges exceeding female ranges. Males overlapped more females than males, while sharing similar food preferences and use patterns with females, suggesting that the sexual dimorphism in home range size is related to mate searching. Roads and oil extraction pads were used less frequently than expected and were incorporated into home ranges less than randomly generated features. The importance of cypress domes within the wet forests and grasslands of Big Cypress National Preserve demonstrates the value of maintaining this delicate mosaic.

  16. Big Cypress fox squirrel (Sciurus niger avicennia) ecology and habitat use in a cypress dome swamp-pine forest mosaic

    PubMed Central

    Kellam, John O.; Jansen, Deborah K.; Johnson, Annette T.; Arwood, Ralph W.; Merrick, Melissa J.; Koprowski, John L.

    2016-01-01

    Forested wetlands are in decline, as are many species that are obligate residents. Big Cypress fox squirrels (BCFS; Sciurus niger avicennia) are a threatened endemic to wet pine and cypress forests in southwestern Florida. The region is characterized by development resulting in habitat loss, habitat fragmentation, and hydrological change that influence the quality of these wet forests. Through radiotelemetry and field observations, we examined the ecology and habitat use of BCFS in a natural cypress dome-pine forest mosaic. BCFS selected cypress domes for food and nests throughout the year. Cypress dome habitats were the only habitat type to be used more than available; however, the availability of nearby pine forest was also important. Home ranges were large relative to other tree squirrels, with male home ranges exceeding female ranges. Males overlapped more females than males, while sharing similar food preferences and use patterns with females, suggesting that the sexual dimorphism in home range size is related to mate searching. Roads and oil extraction pads were used less frequently than expected and were incorporated into home ranges less than randomly generated features. The importance of cypress domes within the wet forests and grasslands of Big Cypress National Preserve demonstrates the value of maintaining this delicate mosaic. PMID:26989265

  17. Very low levels of direct additive genetic variance in fitness and fitness components in a red squirrel population

    PubMed Central

    McFarlane, S Eryn; Gorrell, Jamieson C; Coltman, David W; Humphries, Murray M; Boutin, Stan; McAdam, Andrew G

    2014-01-01

    A trait must genetically correlate with fitness in order to evolve in response to natural selection, but theory suggests that strong directional selection should erode additive genetic variance in fitness and limit future evolutionary potential. Balancing selection has been proposed as a mechanism that could maintain genetic variance if fitness components trade off with one another and has been invoked to account for empirical observations of higher levels of additive genetic variance in fitness components than would be expected from mutation–selection balance. Here, we used a long-term study of an individually marked population of North American red squirrels (Tamiasciurus hudsonicus) to look for evidence of (1) additive genetic variance in lifetime reproductive success and (2) fitness trade-offs between fitness components, such as male and female fitness or fitness in high- and low-resource environments. “Animal model” analyses of a multigenerational pedigree revealed modest maternal effects on fitness, but very low levels of additive genetic variance in lifetime reproductive success overall as well as fitness measures within each sex and environment. It therefore appears that there are very low levels of direct genetic variance in fitness and fitness components in red squirrels to facilitate contemporary adaptation in this population. PMID:24963372

  18. Predictive habitat models derived from nest-box occupancy for the endangered Carolina northern flying squirrel in the southern Appalachians

    USGS Publications Warehouse

    Ford, W. Mark; Evans, A.M.; Odom, Richard H.; Rodrigue, Jane L.; Kelly, C.A.; Abaid, Nicole; Diggins, Corinne A.; Newcomb, Doug

    2016-01-01

    In the southern Appalachians, artificial nest-boxes are used to survey for the endangered Carolina northern flying squirrel (CNFS; Glaucomys sabrinus coloratus), a disjunct subspecies associated with high elevation (>1385 m) forests. Using environmental parameters diagnostic of squirrel habitat, we created 35 a priori occupancy models in the program PRESENCE for boxes surveyed in western North Carolina, 1996-2011. Our best approximating model showed CNFS denning associated with sheltered landforms and montane conifers, primarily red spruce Picea rubens. As sheltering decreased, decreasing distance to conifers was important. Area with a high probability (>0.5) of occupancy was distributed over 18662 ha of habitat, mostly across 10 mountain ranges. Because nest-box surveys underrepresented areas >1750 m and CNFS forage in conifers, we combined areas of high occupancy with conifer GIS coverages to create an additional distribution model of likely habitat. Regionally, above 1385 m, we determined that 31795 ha could be occupied by CNFS. Known occupied patches ranged from

  19. Patterns of ectoparasitism in North American red squirrels (Tamiasciurus hudsonicus): Sex-biases, seasonality, age, and effects on male body condition

    PubMed Central

    Patterson, Jesse E.H.; Neuhaus, Peter; Kutz, Susan J.; Ruckstuhl, Kathreen E.

    2015-01-01

    Within many species, males are often more heavily parasitised than females. Several hypotheses have been proposed to explain this phenomenon, including immunocompetence handicaps, sexual size dimorphism and behavioural differences. Here we set out to test the latter two hypotheses and make inferences about the former by assessing patterns of ectoparasitism across various life-history stages in a population of North American red squirrels (Tamiasciurus hudsonicus). We also conducted an ectoparasite removal experiment to investigate the effects of ectoparasites on male body condition. We found that males were more intensely parasitized than females, but only during the mating period. There was no difference in ectoparasite intensity between male and female juveniles at birth or at emergence, suggesting that ectoparasites do not exploit male red squirrels for longer-range natal dispersal. Male red squirrels in our population were slightly heavier than females, however we did not find any evidence that this dimorphism drives male-biased ectoparasitism. Finally, we could not detect an effect of ectoparasite removal on male body mass. Our results lend support to the hypothesis that ectoparasites exploit their male hosts for transmission and that male red squirrels are important for the transmission dynamics of ectoparasites in this population; however, the mechanisms (i.e., immunocompetence, testosterone) are not known. PMID:26236631

  20. Late winter and early spring home range and habitat use of the endangered Carolina northern flying squirrel in western North Carolina

    USGS Publications Warehouse

    Ford, W. Mark; Kelly, Christine A.; Rodrigue, Jane L.; Odom, Richard H.; Newcomb, Douglas; Gilley, L. Michelle; Diggins, Corinne A.

    2014-01-01

    The Carolina northern flying squirrel Glaucomys sabrinus coloratus is an endangered subspecies that is restricted to high elevation forests in the southern Appalachian Mountains. Owing to rugged terrain and nocturnal habits, the subspecies’ natural history, home range characteristics and habitat preferences are poorly known. We radio-tracked 3 female and 2 male Carolina northern flying squirrels during late winter through spring 2012 in the Pisgah National Forest, North Carolina, USA. Tracked squirrels used 13 yellow birch Betula alleghaniensis and 9 red spruce Picea rubens as diurnal dens. Ten of the yellow birch dens were in cavities, whereas the remainders were dreys. Conversely, 8 of the red spruce dens were dreys and one was in a cavity. Mean (±SE) female 95 and 50% adaptive kernel home ranges were 6.50 ± 2.19 and 0.93 ± 0.33 ha, respectively, whereas the corresponding values for males were 12.6 ± 0.9 and 1.45 ± 0.1 ha, respectively. Squirrels used red spruce stands with canopies >20 m more than expected based on availability at the landscape and home range scales. Results should be interpreted cautiously because of small sample sizes and seasonal observations; however, they provide evidence that although northern hardwoods such as yellow birch are an important den habitat component, mature red spruce-dominated habitats with complex structure provide foraging habitats and are also den habitat. Our findings support efforts to improve the structural condition of extant red spruce forests and/or increase red spruce acreage to potentially benefit Carolina northern flying squirrels.

  1. Evaluation of Immunocontraception as a Publicly Acceptable Form of Vertebrate Pest Species Control: The Introduced Grey Squirrel in Britain as an Example

    NASA Astrophysics Data System (ADS)

    Barr, Julian J. F.; Lurz, Peter W. W.; Shirley, Mark D. F.; Rushton, Steve P.

    2002-09-01

    We sent out a targeted questionnaire to organizations and private individuals across the UK that have expressed an interest in squirrel management and conservation. Respondents were asked to evaluate shooting, trapping, poisoning and immunocontraception (IMC), according to their perceived efficacy, cost efficiency, and whether they were considered to be humane. The majority of both professionals and enthusiasts indicated support for grey squirrel control to help conserve red squirrels and to reduce economic damage to timber crops. Respondents' comparative evaluations of current forms of control showed that trapping is the most acceptable method. When IMC is compared with the other methods, it was considered to be more humane and acceptable. In contrast, poisoning was seen as humane or acceptable by the fewest respondents. Furthermore, poisoning elicited the greatest difference in opinion between the professional and enthusiast groups. This difference (34%) may be interpreted partly as concern over the type of death that results from poisoning and partly as due to the possibility of poisoning nontarget species. Our findings indicate a need for more public information regarding secondary poisoning hazards to other species and their predators. Interest and concern about squirrel control correlated with the overlap between contemporary areas of distribution of the two species. It is these areas where consultation and education programs about control methods should be targeted. This research indicates that there would be support for grey squirrel control using IMC from both lay and professional interest groups. It demonstrates the existence of a sound basis for constructive dialog that can lead to the design and implementation of acceptable and efficient control strategies.

  2. Antagonism of metabotropic glutamate 1 receptors attenuates behavioral effects of cocaine and methamphetamine in squirrel monkeys.

    PubMed

    Achat-Mendes, Cindy; Platt, Donna M; Spealman, Roger D

    2012-10-01

    Within the group I family of metabotropic glutamate receptors (mGluRs), substantial evidence points to a role for mGluR5 mechanisms in cocaine's abuse-related behavioral effects, but less is understood about the contribution of mGluR1, which also belongs to the group I mGluR family. The selective mGluR1 antagonist JNJ16259685 [(3,4-dihydro-2H-pyrano-[2,3-b]quinolin-7-yl)-(cis-4-methoxycyclohexyl)-methanone] was used to investigate the role of mGluR1 in the behavioral effects of cocaine and methamphetamine. In drug discrimination experiments, squirrel monkeys were trained to discriminate cocaine from saline by using a two-lever, food-reinforced operant procedure. JNJ16259685 (0.56 mg/kg) pretreatments significantly attenuated cocaine's discriminative stimulus effects and the cocaine-like discriminative stimulus effects of methamphetamine. In monkeys trained to self-administer cocaine or methamphetamine under a second-order schedule of intravenous drug injection, JNJ16259685 (0.56 mg/kg) significantly reduced drug-reinforced responding, resulting in a downward displacement of dose-response functions. In reinstatement studies, intravenous priming with cocaine accompanied by restoration of a cocaine-paired stimulus reinstated extinguished cocaine-seeking behavior, which was significantly attenuated by JNJ16259685 (0.56 mg/kg). Finally, in experiments involving food rather than drug self-administration, cocaine and methamphetamine increased the rate of responding, and the rate-increasing effects of both psychostimulants were significantly attenuated by JNJ16259685 (0.3 mg/kg). At the doses tested, JNJ16259685 did not significantly suppress food-reinforced behavior (drug discrimination or fixed-interval schedule of food delivery), but did significantly reduce species-typical locomotor activity in observational studies. To the extent that the psychostimulant-antagonist effects of JNJ16259685 are independent of motor function suppression, further research is warranted to

  3. Seminal characteristics and cryopreservation of sperm from the squirrel monkey, Saimiri collinsi.

    PubMed

    Oliveira, K G; Leão, D L; Almeida, D V C; Santos, R R; Domingues, S F S

    2015-09-15

    The Neotropical nonhuman primate squirrel monkey (Saimiri sp.) is one of the most commonly used species in research in several areas of knowledge. However, little progress has been reported in respect to techniques for preservation of their gametes. Thus, the main objectives of this study were (1) to describe testicular and seminal aspects of a new species, Saimiri collinsi, (2) to preserve semen of this species by cooling or freezing using ACP-118 (powdered coconut water), and (3) to test two glycerol (GLY) concentrations (1.5% or 3%) for semen freezing in the presence of ACP-118. The experimental group started with 14 captive males, but only 11 were suitable to collect ejaculates containing sperm. After anesthesia, both testes were evaluated: length, width, height, and testicular circumference. Semen was collected by electroejaculation and evaluated, followed by dilution, cooling, and freezing. Seminal parameters and sperm motility, vigor, plasma membrane integrity, and normal morphology were evaluated after each step; functionality was also checked in fresh and frozen-thawed sperm. Sperm motility, plasma membrane integrity, and normal sperm in cooled semen (n = 11) were 44.1 ± 34.0, 63.1 ± 15.6, and 73.8 ± 19.8, respectively, with vigor ranging of 2 to 3. Sperm motility, plasma membrane integrity, normal and functional sperm in frozen semen (n = 5) were 0.6 ± 1.3 (1.5% and 3% GLY); 4.4 ± 4.9 (1.5% GLY) and 6.6 ± 7.2 (3% GLY); 86.8 ± 3.0 (1.5% GLY) and 88.8 ± 5.1 (3% GLY); 13.3 ± 11.9 (1.5% GLY) and 14.3 ± 13.5 (3% GLY), respectively, and vigor 0 for both 1.5% and 3% GLY. No significant difference between GLY concentrations was observed. We concluded that electroejaculation was efficient for semen collection of S collinsi and tested the cooling protocol that allowed to recover a satisfactory percentage (63%) of membrane intact sperm. However, the freezing protocol was not appropriate to sperm preservation.

  4. Physiological identification of morphologically distinct afferent classes innervating the cristae ampullares of the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Lysakowski, A.; Minor, L. B.; Fernandez, C.; Goldberg, J. M.

    1995-01-01

    1. Semicircular-canal afferents in the squirrel monkey were characterized by their resting discharge, discharge regularity, sensitivity to galvanic currents delivered to the ear (beta *), the gain (g2Hz), and phase lead (phi 2Hz) of their response to 2-Hz sinusoidal head rotations, and their antidromic conduction velocity. Discharge regularity was measured by a normalized coefficient of variation (CV*); the higher the CV*, the more irregular the discharge. g2Hz and phi 2Hz were expressed relative to angular head velocity. 2. These physiological measures were used in an attempt to discern the discharge properties of the three morphological classes of afferents innervating the crista. Presumed bouton (B) fibers were identified as slowly conducting afferents. Presumed calyx (C) fibers were recognized by their irregular discharge and low rotational gains. The remaining fibers were considered to be dimorphic (D) units. Single letters (B, C, and D) are used to emphasize that the classification is based on circumstantial evidence and may be wrong for individual fibers. Of the 125 identified fibers, 13 (10%) were B units, 36 (29%) were C units, and 76 (61%) were D units. 3. B units were regularly discharging D units ranged from regularly to irregularly discharging. C units were the most irregularly discharging afferents encountered. The mean resting discharge for the entire sample was 74 spikes/s. Resting rates were similar for regularly discharging B and D units and higher than those for irregularly discharging C and D units. 4. Except for their lower conduction velocities, the discharge properties of B units are indistinguishable from those of regularly discharging D units. Many of the discharge properties of B and D units vary with discharge regularity. There is a strong, positive relation when beta *, g2Hz, or phi 2Hz is plotted against CV*. For beta * or phi 2Hz, C units conform to the relation for B and D units. In contrast, values of g2Hz for C units are three to

  5. The vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Young, L. R.

    1995-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in six male squirrel monkeys during eccentric rotation. Monkeys were rotated in the dark at a constant velocity of 200 degrees/s (centrally or 79 cm off axis) with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's orientation (facing-motion or back-to-motion) had a dramatic influence on the VOR. These experiments show that: (a) the axis of eye rotation always shifted toward alignment with gravito-inertial force; (b) the peak value of horizontal slow phase eye velocity was greater with the monkey facing-motion than with back-to-motion; and (c) the time constant of horizontal eye movement decay was smaller with the monkey facing-motion than with back-to-motion. All of these findings were statistically significant and consistent across monkeys. In another set of tests, the same monkeys were rapidly tilted about their naso-occipital (roll) axis. Tilted orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the angular rotation, no consistent eye velocity response was observed during or following the tilt for any of the six monkeys. The absence of any eye movement response following tilt weighs against the possibility that translational linear VOR responses are due to simple high-pass filtering of the otolith signals. The VOR response during eccentric rotation was divided into the more familiar angular VOR and linear VOR components. The angular component is known to depend upon semicircular canal dynamics and central influences. The linear component of the response decays rapidly with a mean duration of only 6.6 s, while the axis of eye rotation rapidly aligns (< 10 s) with gravito-inertial force. These

  6. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. I. Normal responses

    NASA Technical Reports Server (NTRS)

    Minor, L. B.; Lasker, D. M.; Backous, D. D.; Hullar, T. E.; Shelhamer, M. J. (Principal Investigator)

    1999-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in five squirrel monkeys with intact vestibular function. The VOR evoked by steps of acceleration in darkness (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) began after a latency of 7.3 +/- 1.5 ms (mean +/- SD). Gain of the reflex during the acceleration was 14.2 +/- 5.2% greater than that measured once the plateau head velocity had been reached. A polynomial regression was used to analyze the trajectory of the responses to steps of acceleration. A better representation of the data was obtained from a polynomial that included a cubic term in contrast to an exclusively linear fit. For sinusoidal rotations of 0.5-15 Hz with a peak velocity of 20 degrees /s, the VOR gain measured 0.83 +/- 0.06 and did not vary across frequencies or animals. The phase of these responses was close to compensatory except at 15 Hz where a lag of 5.0 +/- 0.9 degrees was noted. The VOR gain did not vary with head velocity at 0.5 Hz but increased with velocity for rotations at frequencies of >/=4 Hz (0. 85 +/- 0.04 at 4 Hz, 20 degrees /s; 1.01 +/- 0.05 at 100 degrees /s, P < 0.0001). No responses to these rotations were noted in two animals that had undergone bilateral labyrinthectomy indicating that inertia of the eye had a negligible effect for these stimuli. We developed a mathematical model of VOR dynamics to account for these findings. The inputs to the reflex come from linear and nonlinear pathways. The linear pathway is responsible for the constant gain across frequencies at peak head velocity of 20 degrees /s and also for the phase lag at higher frequencies being less than that expected based on the reflex delay. The frequency- and velocity-dependent nonlinearity in VOR gain is accounted for by the dynamics of the nonlinear pathway. A transfer function that increases the gain of this pathway with frequency and a term related to the third power of head

  7. Torsional Eye Movements Evoked by Unilateral Labyrinthine Galvanic Polarizations in the Squirrel Monkey

    NASA Technical Reports Server (NTRS)

    Minor, Lloyd B.; Tomko, David L.; Paige, Gary D.

    1995-01-01

    longer periods of current administration. This adaptation is manifested as a perstimulus return toward resting discharge and poststimulus after-response in the opposite direction (Goldberg et al., 1984; Minor and Goldberg, l991). Cathodal currents (with respect to the perilymphatic space of the vestibule) are excitatory whereas anodal currents are inhibitory. Horizontal eye movements evoked by unilateral galvanic polarizations administered through chronically implanted labyrinthine stimulating electrodes have been studied in alert squirrel monkeys (Minor and Goldberg, 1991). We sought to extend this analysis by recording three-dimensional eye movements during galvanic stimulation. As predicted based upon roughly equal stimulation of ampullary nerves innervating the vertical canals, a substantial torsional component to the nystagmus is noted. The trajectory of torsional slow phases and nystagmus profile after the polarization provide insight into the central mechanisms that influence these responses.

  8. Physiological Adaptations of Arctic Mammals.

    DTIC Science & Technology

    1975-01-01

    Contents #s 1, 2, 3, and 4, and Item G in Expenditures); b) Studies on Hibernation Factor Transferred from Marmots to Test Animals (see Table of Contents...relatives of the woodchuck (i.e. arctic marmots ) also can produce hibernation factor. Credit: *Supported in part by The Arctic Institute of North America...hibernating Arctic marmot , were all capable of inducing the 13-lined ground squirrel to hibernate in the summer, a season when that species would

  9. Morphology and mitochondrial phylogenetics reveal that the Amazon River separates two eastern squirrel monkey species: Saimiri sciureus and S. collinsi.

    PubMed

    Mercês, Michelle P; Lynch Alfaro, Jessica W; Ferreira, Wallax A S; Harada, Maria L; Silva Júnior, José S

    2015-01-01

    Saimiri has a complicated taxonomic history, and there is continuing disagreement about the number of valid taxa. Despite these controversies, one point of consensus among morphologists has been that the eastern Amazonian populations of squirrel monkeys form a single terminal taxon, Saimiri sciureus sciureus (Linnaeus, 1758). This group is distributed to both the north and south of the middle to lower Amazon River and in the Marajó Archipelago. However, a recent molecular study by Lavergne and colleagues suggested that the Saimiri sciureus complex (comprised of S. s. sciureus sensu lato, S. s. albigena, S. s. macrodon, and S. s. cassiquiarensis) was paraphyletic. The discordance between morphological and molecular studies prompted us to conduct a new multidisciplinary analysis, employing a combination of morphological, morphometric, and molecular markers. Our results suggest the currently recognized taxon S. s. sciureus contains two distinct species, recognized by the Phylogenetic Species Concept: Saimiri sciureus (Linnaeus, 1758) and Saimiri collinsi Osgood, 1916. East Amazonian squirrel monkeys north of the Amazon have a gray crown (S. sciureus), and south of the Amazon, the crown is yellow (S. collinsi). Morphometric measurements also clearly distinguish between the two species, with the most important contributing factors including width across upper canines for both sexes. For males, the mean zygomatic breadth was significantly wider in S. sciureus compared to S. collinsi, and for females, the width across the upper molars was wider in S. sciureus compared to S. collinsi. Mitochondrial phylogenetic analyses support this separation of the eastern Amazonian squirrel monkeys into two distinct taxa, recovering one clade (S. sciureus) distributed to the north of the Amazon River, from the Negro River and Branco River to the Guiana coast and the Brazilian state of Amapá, and another clade (S. collinsi) south of the Amazon River, from the region of the Tapaj

  10. Ground water contamination

    SciTech Connect

    Not Available

    1991-01-01

    This book covers: Ground water contamination and basic concepts of water law; Federal law governing water contamination and remediation; Ground water flow and contaminant migration; Ground water cleanup under CERCLA; Technical methods of remediation and prevention of contamination; Liability for ground water contamination; State constraints on contamination of ground water; Water quantity versus water quality; Prevention of use of contaminated ground water as an alternative to remediation; Economic considerations in liability for ground water contamination; and Contamination, extraction, and injection issues.

  11. Dual efferent projections of the trigeminal principal sensory nucleus to the thalamic ventroposteromedial nucleus in the squirrel monkey.

    PubMed

    Ganchrow, D; Mehler, W R

    1986-07-24

    Anterograde degeneration methods demonstrated two efferent components from the trigeminal principal sensory nucleus (PrV) to the thalamic ventroposteromedial nucleus (VPM) in the squirrel monkey: fibers from the dorsal PrV coursed within the central tegmental tract and terminated in a dorsoventromedial strip of the ipsilateral VPM; fibers from the ventral PrV mainly decussated caudal to the interpeduncular nucleus and terminated in the contralateral VPM exclusive of the sector receiving the dorsal PrV component, contralaterally. Adjacent Nissl sections showed an apparent increase in glial profiles accompanying an intense somal staining among the deafferented neuronal population in the VPM, coextensive with those regions in the VPM exhibiting terminal field degeneration.

  12. Biogeography of squirrel monkeys (genus Saimiri): South-central Amazon origin and rapid pan-Amazonian diversification of a lowland primate.

    PubMed

    Lynch Alfaro, Jessica W; Boubli, Jean P; Paim, Fernanda P; Ribas, Camila C; Silva, Maria Nazareth F da; Messias, Mariluce R; Röhe, Fabio; Mercês, Michelle P; Silva Júnior, José S; Silva, Claudia R; Pinho, Gabriela M; Koshkarian, Gohar; Nguyen, Mai T T; Harada, Maria L; Rabelo, Rafael M; Queiroz, Helder L; Alfaro, Michael E; Farias, Izeni P

    2015-01-01

    The squirrel monkey, Saimiri, is a pan-Amazonian Pleistocene radiation. We use statistical phylogeographic methods to create