| isolation of a herpesvirus from the cell culture of a malignant melanoma of a ground squirrel (spermophilus tridecemlineatus). | a subcutaneous neoplastic mass in a 13-lined ground squirrel which metastasized to regional lymph nodes and lung was studied. histopathologically, the tumor architecture and cellular morphology were compatible with that of a malignant amelanotic melanoma. ultrastructurally, the neoplastic tissue was composed of oval cells, spindle-shaped cells, and spindle-shaped cells with electron-dense cytoplasmic granules. virus particles were not seen in these cells. cell cultures from neoplastic tissue gre ... | 1977 | 69409 |
| changes in enzyme levels in the testis and liver of the 13-lined ground squirrel (spermophilus tridecemlineatus) at the time of arousal from hibernation. | male 13-lined ground squirrels induced to emerge from hibernation resumed feeding and gained weight. the weight gain was supported by increases in the levels of glucose 6-phosphate dehydrogenase, l-alanine aminotransferase and carnitine acetyltransferase in the liver. maturation of the testis occurred in a period of about 16 days spanning the time of induced arousal. the testes of hibernating males were characterized by higher levels of l-alanine aminotransferase, glucose 6-phosphate dehydrogena ... | 1977 | 71081 |
| dl-p-chlorophenylalanine effects in thirteen-lined ground squirrels and golden hamsters: evidence for serotonergic regulation of hibernation. | | 1979 | 157312 |
| antimetabolic extract from the brain of the hibernating ground squirrel citellus tridecemlineatus. | extracts of subcortical brains from hibernating ground squirrels, when injected intravenously into rats, caused a mean decrease in oxygen consumption of 35 percent and a decline in body temperature of 5 degree c. the effects lasted from 75 minutes to 30 hours. brain extracts of nonhibernating squirrels caused no significant changes in these parameters. | 1977 | 831261 |
| papillae and galactophore numbers in mammae of cricetus auratus, meriones unguiculatus, spermophilus tridecemlineatus, and chinchilla laniger. | | 1975 | 1113045 |
| reproduction, structure and host specificity of trypanosoma (herpetosoms) tamiasi sp. n. from the eastern chipmunk, tamias striatus. | trypanosoma (herpetosoma) tamiasi sp. n. is described from blood and organs of the eastern chipmunk, tamias striatus, and the least chipmunk, eutamias minimus. in experimentally infected tamias striatus and e. minimus, trypanosoma tamiasi reproduced by equal binary fission in the trypo-, sphaero-, epi-, or amastigote form, mainly in lymphoid organs. trypomastigotes developed from amastigotes through epimastigotes, or from sphaeromastigotes, mainly in the same organs. the mean lengths of body ... | 1975 | 1117439 |
| morphological variation of moniliformis moniliformis (bremser 1811) travassos 1915 and moniliformis clarki (ward 1917) chandler 1921. | a two-way fixed model analysis of variance was used to test moniliformis moniliformis and m. clarki for inter- and intraspecific differences with respect to 7 morphological characters used to distinguish species of the genus. m. clarki was sexually dimorphic in more characters than was m. moniliformis when specimens from their usual definitive hosts, spermophilus tridecemlineatus and rattus norvegicus, respectively, were compared. more characters were sexually dimorphic in both species reared in ... | 1975 | 1195079 |
| thyroid function in a hibernator, spermophilus tridecemlineatus. | thyroid hormone secretion (assessed as thyroid 125i release rate) was monitored in spermophilus tridecemlineatus from summer to winter (july-december) in 1973. the average release rate in july was 2.3% per day, but in august this rate decreased significantly and remained at an average 0.52% per day until december. this low rate (being similar to that of hypophysectomized rats), and the absence of any change in oxygen consumption following thyroidectomy, suggested hormone secretion was "turned of ... | 1976 | 1275061 |
| diversities of transport of sodium in rodent red cells. | 1. na-k pumps of rodent red cells reveal variations among species in terms of kinetic properties such as ouabain sensitivity, na/k coupling and temperature sensitivity and variations within an individual organism related to such physiological challenges as k deficiency, calorie deficiency and seasonal changes in temperature. 2. passive na entry among rodents collectively occurs through the same routes as in red cells of other mammals, but red cells of hamsters, rats and thirteen-lined ground squ ... | 1992 | 1355023 |
| thalamic connections of the ground squirrel superior colliculus and their topographic relations. | the connections of the superior colliculus (sc) of the ground squirrel spermophilus tridecemlineatus were studied with the horseradish peroxidase (hrp) method. multiple pressure injections of hrp served to define the total pattern of sc projections while iontophoretic injections allowed differentiation of connections of the deep and superficial layers and determination of topographic relations of sc with its associated nuclei. the deep laminae were mainly connected with auditory, somatosensory a ... | 1988 | 2457050 |
| photically responsive neurons in the hypothalamus of a diurnal ground squirrel. | the suprachiasmatic nuclei (scn) function as a circadian pacemaker. entrainment to the external light-dark cycle is mediated by the retina which gives rise to both direct and indirect projections to the scn. the hypothalamic targets of the retinohypothalamic tract (rht) were investigated in thirteen-lined ground squirrels (spermophilus tridecemlineatus) following wga-hrp injections. the results indicate that retinal fibers project to the entire scn. extracellular single-unit activity was recorde ... | 1989 | 2479451 |
| ventilatory responses of the ground squirrel, spermophilus tridecemlineatus, to various levels of hypoxia. | 1. minute ventilation (ve) in the semifossorial ground squirrel (spermophilus tridecemlineatus) increased with increased levels of hypoxia. 2. the increase in ve was brought about primarily by an increase in breathing frequency (f). there was no significant change in tidal volume (vt). 3. the pio2 threshold for the ventilatory response to hypoxia and position of the ventilatory response curve in the ground squirrel were closer to the semifossorial echidna (tachyglossus aculeatus) than the comple ... | 1989 | 2566413 |
| opioids and hibernation. i. effects of naloxone on bear hit's depression of guinea pig ileum contractility and on induction of summer hibernation in the ground squirrel. | summer hibernation in ground squirrels (citellus tridecemlineatus) can be induced by intravenous injection of hibernation-induction trigger (hit) from winter bear plasma or its albumin fraction. in this study, we show that bear hit depresses electrically-induced contraction of the guinea pig ileum myenteric plexus-longitudinal muscle preparation, and that naloxone, at 100, 1,000, or even 4,000 nm, fails to reverse that effect. in a simultaneous study, four sets of ground squirrels were implanted ... | 1987 | 2823038 |
| opioids and hibernation. ii. effects of kappa opioid u69593 on induction of hibernation in summer-active ground squirrels by "hibernation induction trigger" (hit). | a "hibernation induction trigger" (hit) isolated from plasma of winter-hibernating woodchucks induced hibernation in summer-active ground squirrels (citellus tridecemlineatus). effects of kappa opioid u69593 on the hit-induced hibernation were examined. u69593 alone did not elicit marked behavioral alteration or hibernation in summer-active ground squirrels. u69593, however, antagonized hibernation induced by hit in summer active ground squirrels. in the guinea pig ileum myenteric plexus-longitu ... | 1987 | 2823039 |
| presence of intranuclear inclusions in the principal cells of the epididymis of the garden dormouse eliomys quercinus l. | globular inclusions are present in the nuclei of the columnar epithelial cells lining the ductus epididymidis in the garden dormouse, eliomys quercinus l. such inclusions have been reported in the dog where they are very abundant, in the stallion and in man. they have been found to be absent from sheep, cat, rabbit, guinea pig, rat and mouse. we have now found them in the garden dormouse, an ascrotal hibernator, but have been unable to detect them in another hibernator, the thirteen-lined ground ... | 1988 | 2840196 |
| coronary autoregulation and metabolism in hypothermic rat and ground squirrel hearts. | an isovolumic langendorff preparation was used to perfuse rat and ground squirrel (spermophilus tridecemlineatus) hearts at 37, 27, 17, and 7 degrees c. perfusion pressure (pp) was randomly increased or decreased (40, 60, 70, 110, 120, or 140 mmhg) from a control pp of 90 mmhg. coronary flow (cf) was measured immediately after each pp change (initial cf) and after stable flow was observed (final cf). compared with initial flow, final cf was decreased at high pps or increased at low pps (autoregu ... | 1989 | 2916694 |
| cardiac arrhythmias during arousal from hibernation in three species of rodents. | cardiac activity was monitored during arousal from deep hibernation in three species of hibernators (citellus tridecemlineatus, marmota monax, and mesocricetus auratus). individuals of each species showed marked arrhythmias, and these were confined to a body temperature range of between 11 and 20 degrees c, measured orally or rectally. the arrhythmias consisted of intermittent periods of asystole and bradycardia and were sometimes marked by the appearance of premature ventricular contractions an ... | 1988 | 3276222 |
| effect of cooling on vascular smooth muscle from the thirteen-lined ground squirrel. | peripheral vascular resistance in the ground squirrel (spermophilus tridecemlineatus) increases when the animal enters hibernation. the goals of this study were to determine if a change in vascular reactivity contributes to this hemodynamic response, and to compare the effects of temperature on vascular responsiveness in a hibernator (ground squirrel) and a nonhibernating mammal (rat). helically cut strips of aortae and femoral arteries were mounted in organ chambers (37 degrees c) and isometric ... | 1987 | 3816289 |
| the replication of poliovirus in primary kidney cell cultures of thirteen-lined ground squirrels. | | 1971 | 4330236 |
| dehydration and body fluid regulation in the thirteen-lined ground squirrel and laboratory rat. | | 1973 | 4700642 |
| development of the secondary hemolysin response in hibernating ground squirrels (citellus tridecemlineatus). | | 1968 | 5246933 |
| potential of kidney cell cultures from nonhibernating thirteen-lined ground squirrels (citellus tridecemlineatus) for virus propagation. | kidney cells were cultured in vitro from nonhibernating thirteen-lined ground squirrels (citellus tridecemlineatus). these primary ground squirrel kidney cultures were tested for the ability to support the replication of 13 viruses representing nine virus groups. the cultures were shown to be susceptible to every virus tested, either by an increase in infectious virus or by the cytopathic effect produced. | 1970 | 5498609 |
| resistance of the thirteen-striped ground squirrel (citellus tridecemlineatus) to infection with plasmodium berghei. | | 1968 | 5641038 |
| a comparative study of the visual system in the diurnal ground squirrel, citellus tridecemlineatus tridecemlineatus and in the nocturnal guinea pig, cavia cobaya. | | 1965 | 5884370 |
| effect of hibernation on course of infection and immune response in citellus tridecemlineatus infected with nippostrongylus brasiliensis. | | 1967 | 6017221 |
| fasciola hepatica in hibernating citellus tridecemlineatus (mitchell). | | 1967 | 6062059 |
| kinetics of the sodium pump in red cells of different temperature sensitivity. | ouabain-sensitive k influx into ground squirrel and guinea pig red cells was measured at 5 and 37 degrees c as a function of external k and internal na. in both species the external k affinity increases on cooling, being three- and fivefold higher in guinea pig and ground squirrel, respectively, at 5 than at 37 degrees c. internal na affinity also increased on cooling, by about the same extent. the effect of internal na on ouabain-sensitive k influx in guinea pig cells fits a cubic michaelis-men ... | 1982 | 6286844 |
| differential effects of temperature on three components of passive permeability to potassium in rodent red cells. | the effect of temperature on ouabain-insensitive fluxes of k+ was characterized in red cells from a non-hibernator (guinea-pig) and a hibernator (thirteen-lined ground squirrel). the residual k+ influx which remains in the presence of ouabain and bumetanide, and which is linearly dependent on [k+]o was the same in the erythrocytes of the two species at low temperature (5 degrees c). at 5 degrees c co-transport of k+ was abolished in guinea-pig red cells but was still present in ground squirrel r ... | 1984 | 6325676 |
| replication of mycobacterium leprae in hibernating ground squirrels (citellus tridecemlineatus). | subcutaneous injections of 10(6) acid-fast bacteria from human lepromatous tissue to hibernating ground squirrels (citellus tridecemlineatus) is followed by generalized infection of the animals and spontaneous death. the number of mycobacteria is high in the skin of gs during winter and decreases during summer. animals surviving the first hibernation period invariably die during the second. the number of microorganism in the visceral organs is low at all times. the system of infected hibernating ... | 1982 | 6818816 |
| do retinal ganglion cells project bilaterally in ground squirrels? | bilaterally projecting retinal ganglion cells have recently been reported in the japanese monkey macaca fuscata and albino rat. in the present experiments, we sought to determine whether ganglion cells project bilaterally in the 13-lined ground squirrel spermophilus tridecemlineatus. we injected rhodamine-conjugated latex microspheres (red beads) into the right optic tract, superior colliculus and the dorsal lateral geniculate nucleus and fitc-conjugated latex microspheres (green beads) into the ... | 1995 | 7757471 |
| expression of soluble phototransduction-associated proteins in ground squirrel retina. | this study describes the expression and distribution of arrestin, phosducin, and recoverin in the cone-dominant retina of the ground squirrel spermophilus tridecemlineatus. | 1994 | 7928190 |
| body temperature and behaviour of golden hamsters (mesocricetus auratus) and ground squirrels (spermophilus tridecemlineatus) in a thermal gradient. | golden hamsters and thirteen-lined ground squirrels were maintained individually in a thermal gradient (14 degrees c to 33 degrees c) for several weeks under a 14l:10d light-dark cycle. animals of both species showed robust daily rhythms of body temperature and locomotor activity with acrophases consistent with the habits of the species (diurnal acrophases in the diurnal squirrels and nocturnal acrophases in the nocturnal hamsters). hamsters showed a robust daily rhythm of temperature selection ... | 1995 | 8537937 |
| comparison of the body temperature rhythms of diurnal and nocturnal rodents. | the daily rhythm of body temperature of six rodent species, three of them nocturnal (rattus norvegicus, mesocricetus auratus, and meriones unguiculatus) and three diurnal (octodon degus, spermophilus tridecemlineatus, and s. richardsoni), was studied by telemetry under a 14l:10d light-dark cycle. significant interspecies differences were found in the mean level (range: 36.0-37.4 degrees c), amplitude (range: 2.1 degrees-4.3 degrees c), robustness (range: 115-185 qp), and acrophase (range: 8.5-16 ... | 1996 | 8708632 |
| cadp44: a novel regulatory subunit of the 26s proteasome and the mammalian homolog of yeast sug2p. | we have identified a novel protein, cadp44, based on the analysis of cdnas derived from the brainstem of the 13-lined ground squirrel, spermophilus tridecemlineatus. cadp44 has an unmodified molecular mass of 44,178 da and contains multiple functional domains, including a conserved atpase domain (cad) and a leucine zipper motif. we show that distinct regions of the cadp44 sequence are identical to a set of peptides prepared from a recently identified bovine protein, referred to as p42, which is ... | 1996 | 8973309 |
| dynamics of plague in a gunnison's prairie dog colony complex from new mexico. | a plague (yersinia pestis) epizootic spread through gunnison's prairie dogs (cynomys gunnisoni), and possibly other rodent species, in the moreno valley in north-central new mexico between winter 1984-1985 and autumn 1987. we observed the progress of the epizootic and subsequent population recovery at four prairie dog towns within the valley during this period. at two towns (midlake and val verde) the prairie dogs were marked prior to the epizootic. at two additional towns (vega and south entran ... | 1997 | 9391954 |
| effects of plasma from hibernating ground squirrels on monocyte-endothelial cell adhesive interactions. | adhesion and subsequent penetration of leukocytes into central nervous system ischemic tissue proceeds via a coordinated inflammatory mechanism involving adhesion molecules at the blood-endothelium interface. mammalian hibernation is a state of natural tolerance to severely reduced blood flow-oxygen delivery (i.e., ischemia). hibernating thirteen-lined ground squirrels were investigated in an attempt to identify factors responsible for regulating this tolerance. since leukocytopenia is closely a ... | 1997 | 9435638 |
| hibernation in ground squirrels induces state and species-specific tolerance to hypoxia and aglycemia: an in vitro study in hippocampal slices. | hibernation in mammals is associated with a regulated depression of global cellular functions accompanied by reductions of cerebral blood flow that would render the brain profoundly ischemic under normal conditions. homeostatic control is preserved, however, and brain damage does not occur. we investigated the possibility that hibernation not only confers tolerance to profound hypothermia, but also to hypoxia and aglycemia independent of temperature. hippocampal slices from ground squirrels cite ... | 1998 | 9469159 |
| cloning of a cyclic gmp phosphodiesterase gamma subunit from the ground squirrel retina. | recent evidence suggests that the two main classes of cones are not only equipped with different photopigments, but also exhibit differences in their downstream phototransduction cascade. an antibody against the gamma subunit of retinal cgmp phosphodiesterase (pde) had previously been found to label all photoreceptors in the ground squirrel (spermophilus tridecemlineatus). this property was utilized for the cloning of a cdna fragment encoding the corresponding polypeptide. a lambda gt11 cdna lib ... | 1998 | 9555081 |
| four retinal ganglion cell types that project to the superior colliculus in the thirteen-lined ground squirrel (spermophilus tridecemlineatus). | the morphology of retinal ganglion cells projecting to the superior colliculus (sc) of the thirteen-lined ground squirrel (spermophilus tridecemlineatus) was studied after retrogradely labeling the cells with cholera toxin subunit b. on the basis of previous reports, labeled cells were classified as small (6-10 microm in soma diameter), medium (11-14 microm), or large (>14 microm). a total of 3,427 cells were studied. small cells constituted 78% of the population, 21% were medium cells, and only ... | 1998 | 9623890 |
| the cloning of grk7, a candidate cone opsin kinase, from cone- and rod-dominant mammalian retinas. | desensitization in the rod cell of the mammalian retina is initiated when light-activated rhodopsin is phosphorylated by the g protein-coupled receptor kinase (grk), grk1, often referred to as rhodopsin kinase. a distinct kinase that specifically phosphorylates cone opsins in a similar manner has not been identified in mammals. to determine the existence of a cone opsin kinase, rna from the retinas of cone- and rod-dominant mammals was analyzed by pcr. | 1998 | 9852166 |
| cycle of period gene expression in a diurnal mammal (spermophilus tridecemlineatus): implications for nonphotic phase shifting. | ground squirrels, spermophilus tridecemlineatus, were kept in a 12:12 h light-dark cycle. as expected for a diurnal species, their locomotor activity occurred almost entirely in the daytime. expression of mper1 and mper2 in the suprachiasmatic nucleus was studied at six time points by in situ hybridization. for both these genes, mrna was highest in the first part of the subjective day (about zeitgeber time 5). this is close to the time when mper1 and mper2 expression is maximal in nocturnal rode ... | 2001 | 11669420 |
| differential expression of adipose- and heart-type fatty acid binding proteins in hibernating ground squirrels. | the up-regulation of heart- and adipose-type fatty acid binding proteins (h-fabps and a-fabps) was detected during hibernation in brown adipose tissue (bat) of 13-lined ground squirrels, spermophilus tridecemlineatus, using a commercial rat cdna array. full length cdnas encoding h-fabps and a-fabps were subsequently retrieved from a bat cdna library. these cdnas were used to probe northern blots of total rna from tissues of euthermic versus hibernating ground squirrels. h-fabp mrna transcripts i ... | 2001 | 11779641 |
| coordinate expression of the pdk4 gene: a means of regulating fuel selection in a hibernating mammal. | hibernation in mammals requires a metabolic shift away from the oxidation of carbohydrates and toward the combustion of stored fatty acids as the primary source of energy during torpor. a key element involved in this fuel selection is pyruvate dehydrogenase kinase isoenzyme 4 (pdk4). pdk4 inhibits pyruvate dehydrogenase and thus minimizes carbohydrate oxidation by preventing the flow of glycolytic products into the tricarboxylic acid cycle. this paper examines expression of the pdk4 gene during ... | 2002 | 11842126 |
| the translation state of differentially expressed mrnas in the hibernating 13-lined ground squirrel (spermophilus tridecemlineatus). | the translation state of differentially expressed mrnas were compared in kidney and brown adipose tissue of the hibernating ground squirrel, spermophilus tridecemlineatus. polysome analysis revealed a striking disaggregation of polyribosomes during hibernation and the redistribution of cox4 (cytochrome c oxidase subunit 4) and oct2 (organic cation transporter type 2) transcripts into monosome and mrnp fractions of kidney cytoplasmic extracts. additionally, oct2 protein levels decreased in kidney ... | 2002 | 12054475 |
| antigen disappearance in hibernating ground squirrels. | the rate of antigen disappearance was studied in hibernating ground squirrels (citellus tridecemlineatus) injected with i(131)-labeled bovine serum albumin. there was no detectable disappearance of antigen during 14 days of hibernation. the induction period, however, ended 5 days after arousal as compared to a 7-day induction period in nonhibernating ground squirrels. | 1961 | 13789574 |
| a study of the lateral geniculate body in the diurnal ground squirrel, citellus tridecemlineatus tridecemlineatus and in the nocturnal guinea pig. | | 1963 | 14101911 |
| pancreatic triacylglycerol lipase in a hibernating mammal. i. novel genomic organization. | pancreatic triacylglycerol lipase (ptl) is expressed in novel locations during hibernation in the thirteen-lined ground squirrel (spermophilus tridecemlineatus). ptl cdnas isolated from two of these locations, heart and white adipose tissue (wat), contain divergent 5'-untranslated regions (5'-utrs) suggesting alternative promoter usage or the possibility of multiple ptl genes in the ground squirrel genome. in addition, cdnas isolated from wat contain tracts of retroviral sequence in their 5'-utr ... | 2003 | 14583598 |
| pancreatic triacylglycerol lipase in a hibernating mammal. ii. cold-adapted function and differential expression. | thirteen-lined ground squirrels (spermophilus tridecemlineatus) exploit the low-temperature activity of pancreatic triacylglycerol lipase (ptl) during hibernation. lipolytic activity at body temperatures associated with hibernation was examined using recombinant ground squirrel and human ptls expressed in yeast. both the human and ground squirrel enzymes displayed high activity at temperatures as low as 0 degrees c and showed q10 values of 1.2-1.5 over a range of 37-7 degrees c. these studies in ... | 2003 | 14583599 |
| experimental infection of ground squirrels (spermophilus tridecemlineatus) with monkeypox virus. | a proposed new small-animal (rodent) model for studying the pathogenesis and treatment of severe orthopoxvirus infections is described. thirteen-lined ground squirrels (spermophilus tridecemlineatus) were infected intraperitoneally and intranasally with monkeypox virus (mpxv). a fulminant illness developed in all animals, and they died 6-9 days after infection. virus was cultured from the blood and oropharynx several days before death; at necropsy, all of the organs tested contained relatively h ... | 2004 | 15498157 |
| genes controlling the metabolic switch in hibernating mammals. | hibernating mammals have the ability to decrease their metabolic rate and survive up to 6 months without food in an inactive state where body temperatures approach 0 degrees c. in hibernating 13-lined ground squirrels (spermophilus tridecemlineatus), oxygen consumption holds at 1/30 to 1/50 of the aroused condition and heart rates are as low as 3-10 beats/min, compared with 200-300 beats/min when the animal is active. this seasonal adaptation requires a metabolic shift away from the oxidation of ... | 2004 | 15506953 |
| cloning and expression of hypoxia-inducible factor 1alpha from the hibernating ground squirrel, spermophilus tridecemlineatus. | mammalian hibernation is associated with apnoic breathing patterns and a hypoxia-hypothermia connection has been suggested as part of the mechanism by which body temperature is reduced as animals enter torpor. hence, we hypothesized that changes in the expression of the hypoxia inducible factor (hif-1) may potentially be involved in regulating hibernation-responsive gene targets. the expression of the alpha subunit of hif-1 was quantified at both gene and protein levels in four organs of the thi ... | 2005 | 15811624 |
| effects of hibernation on multicatalytic proteinase complex in thirteen-lined ground squirrels, spermophilus tridecemlineatus. | multicatalytic proteinase complex (mcp) was studied in skeletal muscle of the hibernating ground squirrel, spermophilus tridecemlineatus. mcp was partially purified using a s-400 gel filtration column and centricon concentrating devices and assayed fluorometrically using three amc-labeled substrates. k(m) and v(max) values were determined for each substrate with no significant differences between the enzyme from euthermic versus hibernating animals when assayed at 23 degrees c. however, properti ... | 2005 | 15881672 |
| uv filters in the lens of the thirteen lined ground squirrel (spermophilus tridecemlineatus). | 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 we ... | 2006 | 16297909 |
| rodent-associated bartonella in saskatchewan, canada. | six species of wild rodents were sampled at 10 sites in 2002 and 2003 to determine the prevalence of bartonella infections in rodent communities near saskatoon, saskatchewan, canada. isolates were characterized genotypically and compared with isolates found at other locations. of 104 wild rodents examined, 57% were infected with bartonella and prevalence within species varied from 49% for richardson's ground squirrels (spermophilus richardsonii) to 90% for franklin's ground squirrels (s. frankli ... | 2005 | 16417436 |
| host usage and seasonal activity patterns of ixodes kingi and i. sculptus (acari: ixodidae) nymphs in a colorado prairie landscape, with a summary of published north american host records for all life stages. | we examined host usage and seasonal activity patterns of the nymphal stage of the ticks ixodes kingi and i. sculptus within a prairie rodent community in north-central colorado. ixodes kingi was commonly encountered on both northern grasshopper mice (onychomys leucogaster) and thirteen-lined ground squirrels (spermophilus tridecemlineatus), whereas i. sculptus frequently infested s. tridecemlineatus but was absent from o. leucogaster. low numbers of ticks of both species were collected from deer ... | 2006 | 16859106 |
| changes in neuropeptide y immunoreactivity and transcript levels in circadian system structures of the diurnal rodent, the thirteen-lined ground squirrel. | the intergeniculate leaflet (igl) and its neuropeptide y (npy) projection to the main circadian clock, the suprachiasmatic nucleus (scn), have been the focus of extensive research conducted, for the most part, on nocturnal rodent species. however, a variety of anatomical and physiological differences between the circadian system of diurnal and nocturnal species have been reported. these differences led us to question whether the role of npy in the circadian system of the diurnal ground squirrel ... | 2006 | 17109825 |
| antioxidant defense in hibernation: cloning and expression of peroxiredoxins from hibernating ground squirrels, spermophilus tridecemlineatus. | mammalian hibernation is characterized by prolonged torpor bouts interspersed by brief arousal periods. adequate antioxidant defenses are needed both to sustain cell viability over weeks of deep torpor and to defend against high rates of oxyradical formation associated with massive oxygen-based thermogenesis during arousal. the present study shows that up-regulation of peroxiredoxins contributes to antioxidant defense during torpor in thirteen-lined ground squirrels, spermophilus tridecemlineatu ... | 2007 | 17362873 |
| thirteen-lined ground squirrels (spermophilus tridecemlineatus) harbor multiantibiotic-resistant bacteria. | whether wild-caught animals used for biomedical research carry antibiotic-resistant bacteria is not well studied. thirteen- lined ground squirrels (spermophilus tridecemlineatus) are small mammals used to study hibernation. these animals are captured from the wild or are born in laboratory animal facilities to wild-caught mothers. because microorganisms harbored by 13-lined ground squirrels may be pathogenic to their caretakers and other laboratory animals, learning more about antibiotic resista ... | 2007 | 17487947 |
| mammalian genome projects reveal new growth hormone (gh) sequences. characterization of the gh-encoding genes of armadillo (dasypus novemcinctus), hedgehog (erinaceus europaeus), bat (myotis lucifugus), hyrax (procavia capensis), shrew (sorex araneus), ground squirrel (spermophilus tridecemlineatus), elephant (loxodonta africana), cat (felis catus) and opossum (monodelphis domestica). | mammalian growth hormone (gh) sequences have been shown previously to display episodic evolution: the sequence is generally strongly conserved but on at least two occasions during mammalian evolution (on lineages leading to higher primates and ruminants) bursts of rapid evolution occurred. however, the number of mammalian orders studied previously has been relatively limited, and the availability of sequence data via mammalian genome projects provides the potential for extending the range of gh ... | 2008 | 17574247 |
| exposure of small rodents to plague during epizootics in black-tailed prairie dogs. | plague, caused by the bacterium yersinia pestis, causes die-offs of colonies of prairie dogs (cynomys ludovicianus). it has been argued that other small rodents are reservoirs for plague, spreading disease during epizootics and maintaining the pathogen in the absence of prairie dogs; yet there is little empirical support for distinct enzootic and epizootic cycles. between 2004 and 2006, we collected blood from small rodents captured in colonies in northern colorado before, during, and for up to ... | 2008 | 18689662 |
| adaptive mechanisms regulate preferred utilization of ketones in the heart and brain of a hibernating mammal during arousal from torpor. | hibernating mammals use reduced metabolism, hypothermia, and stored fat to survive up to 5 or 6 mo without feeding. we found serum levels of the fat-derived ketone, d-beta-hydroxybutyrate (bhb), are highest during deep torpor and exist in a reciprocal relationship with glucose throughout the hibernation season in the thirteen-lined ground squirrel (spermophilus tridecemlineatus). ketone transporter monocarboxylic acid transporter 1 (mct1) is upregulated at the blood-brain barrier, as animals ent ... | 2009 | 19052316 |
| susceptibility of the gopher (citellus tridecemlineatus) to mycobacterium tuberculosis. | | 1931 | 19969954 |
| heme oxygenase expression and nrf2 signaling during hibernation in ground squirrels. | mammalian hibernation is composed of long periods of deep torpor interspersed with brief periods of arousal in which the animals, fueled by high rates of oxygen-based thermogenesis in brown adipose tissue and skeletal muscle, power themselves back to euthermic (~37 degrees c) body temperatures. strong antioxidant defences are important both for long-term cytoprotection during torpor and for coping with high rates of reactive oxygen species generated during arousal. the present study shows that t ... | 2010 | 20393602 |
| thomas george lee - implantation and early development of north american rodents. | a century ago thomas g. lee amassed an unparalleled collection of developmental series of north american rodents such as the thirteen-lined ground squirrel, the plains pocket gopher and merriam's kangaroo rat. he was the first to describe the initial attachment of the squirrel blastocyst to the antimesometrial side of the uterus. the full potential of lee's material was not realized until after his death, when it came into the possession of mossman. the latter relied heavily on lee's collection ... | 2010 | 20947162 |
| permanent genetic resources added to molecular ecology resources database 1 january 2009-30 april 2009. | this article documents the addition of 283 microsatellite marker loci to the molecular ecology resources database. loci were developed for the following species: agalinis acuta; ambrosia artemisiifolia; berula erecta; casuarius casuarius; cercospora zeae-maydis; chorthippus parallelus; conyza canadensis; cotesia sesamiae; epinephelus acanthistius; ficedula hypoleuca; grindelia hirsutula; guadua angustifolia; leucadendron rubrum; maritrema novaezealandensis; meretrix meretrix; nilaparvata lugens; ... | 2009 | 21564911 |
| deep sequencing the transcriptome reveals seasonal adaptive mechanisms in a hibernating mammal. | mammalian hibernation is a complex phenotype involving metabolic rate reduction, bradycardia, profound hypothermia, and a reliance on stored fat that allows the animal to survive for months without food in a state of suspended animation. to determine the genes responsible for this phenotype in the thirteen-lined ground squirrel (ictidomys tridecemlineatus) we used the roche 454 platform to sequence mrna isolated at six points throughout the year from three key tissues: heart, skeletal muscle, an ... | 2011 | 22046435 |
| Structural and Functional Properties of Glycerol-3-Phosphate Dehydrogenase from a Mammalian Hibernator. | Glycerol-3-phosphate dehydrogenase (G3PDH; E.C.1.1.1.8) was purified from liver and skeletal muscle of black-tailed prairie dogs (Cynomys ludivicianus), a hibernating species. Native and subunit molecular masses of the dimeric enzyme were 77 and 40 kD, respectively, and both tissues contained a single isozyme with a pI of 6.4. Kinetic parameters of purified G3PDH from prairie dog liver and muscle were characterized at 22 and 5 °C and compared with rabbit muscle G3PDH. Substrate affinities for hi ... | 2011 | 22180227 |
| several blood and circulatory changes in the hibernation of the 13-lined ground squirrel, citellus tridecemlineatus. | | 2014 | 4145748 |
| the involvement of mrna processing factors tia-1, tiar, and pabp-1 during mammalian hibernation. | mammalian hibernators survive low body temperatures, ischemia-reperfusion, and restricted nutritional resources via global reductions in energy-expensive cellular processes and selective increases in stress pathways. consequently, studies that analyze hibernation uncover mechanisms which balance metabolism and support survival by enhancing stress tolerance. we hypothesized processing factors that influence messenger ribonucleic acid (mrna) maturation and translation may play significant roles in ... | 2014 | 24590458 |
| capture of syncytin-mar1, a fusogenic endogenous retroviral envelope gene involved in placentation in the rodentia squirrel-related clade. | 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 g ... | 2014 | 24789792 |
| inhibition of borna disease virus replication by an endogenous bornavirus-like element in the ground squirrel genome. | 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 ... | 2014 | 25157155 |
| north american tree squirrels and ground squirrels with overlapping ranges host different cryptosporidium species and genotypes. | 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 ... | 2015 | 26437239 |
| molecular cloning, characterization and expression analysis of tgf-β and receptor genes in the woodchuck model. | transforming growth factor beta (tgf-β) is an important cytokine with pleiotropic regulatory functions in the immune system and in the responses against viral infections. tgf-β acts on a variety of immune cells through the cell surface tgf-β receptor (university of duisburg-essentgfbr). the woodchuck has been used as a biomedical model for studies of obesity and energy balance, endocrine and metabolic function, cardiovascular, cerebrovascular and neoplastic disease. woodchucks infected with wood ... | 2016 | 27637515 |
| molecular cloning, characterization and expression analysis of tim-3 and galectin-9 in the woodchuck model. | in recent years, a critical role for t cell immunoglobulin mucin domain 3 (tim-3) and its ligand galectin-9 (gal-9) has emerged in infectious disease, autoimmunity and cancer. manipulating this immune checkpoint may have immunotherapeutic potential and could represent an alternative approach for improving immune responses to viral infections and cancer. the woodchuck (marmot monax) infected by woodchuck hepatitis virus (whv) represents an informative animal model to study hbv infection and hcc. ... | 2017 | 28152393 |
| impacts of tree rows on grassland birds and potential nest predators: a removal experiment. | globally, grasslands and the wildlife that inhabit them are widely imperiled. encroachment by shrubs and trees has widely impacted grasslands in the past 150 years. in north america, most grassland birds avoid nesting near woody vegetation. because woody vegetation fragments grasslands and potential nest predator diversity and abundance is often greater along wooded edge and grassland transitions, we measured the impacts of removing rows of trees and shrubs that intersected grasslands on potenti ... | 2013 | 23565144 |
| retinal projections in the ground squirrel (citellus tridecemlineatus). | the retinal projections of the thirteen-lined ground squirrel were determined by tracing anterograde transport of intravitreally injected horseradish peroxidase (hrp) or wheat-germ conjugated horseradish peroxidase (wga-hrp). label was seen in the suprachiasmatic nucleus and adjacent anterior hypothalamic area, the accessory optic system (the medial, dorsal, and lateral terminal nuclei), the dorsal and ventral lateral geniculate nuclei, the intergeniculate leaflet, the pretectal nuclei (the ante ... | 1989 | 2484824 |
| striped pattern of labeling in ground squirrel superior colliculus following intraocular hrp injections. | in the 13-lined ground squirrel (citellus tridecemlineatus), intravitreal injections of horseradish peroxidase (hrp) or wheat germ-agglutinated hrp (wga-hrp) tracers produced a striped pattern of labeling in the contralateral superficial gray (sgs) of the superior colliculus in most, but not all, cases. the stripes extended dorsoventrally throughout the sgs in a rostral-medial to caudal-lateral orientation. in general, the striped labeling was more distinct and was observed more frequently with ... | 1989 | 2472855 |
| superior colliculus efferents to five subcortical visual system structures in the ground squirrel. | we compared the laminar location and morphology of superior colliculus cells projecting to the dorsal and ventral lateral geniculate nuclei (lgd, lgv), the pretectum (pt), the parabigeminal nucleus (pb), and nucleus lateralis posterior (lp) in the ground squirrel spermophilus tridecemlineatus. horseradish peroxidase was iontophoretically injected into lgd, lgv, pt, pb and each of the 3 subdivisions of the lp. after survival periods of 24-72 h the animals were perfused intracardially and brain se ... | 1987 | 3690310 |
| review of anthraquinone applications for pest management and agricultural crop protection. | we have reviewed published anthraquinone applications for international pest management and agricultural crop protection from 1943 to 2016. anthraquinone (aq) is commonly found in dyes, pigments and many plants and organisms. avian repellent research with aq began in the 1940s. in the context of pest management, aq is currently used as a chemical repellent, perch deterrent, insecticide and feeding deterrent in many wild birds, and in some mammals, insects and fishes. criteria for evaluation of e ... | 2016 | 27252044 |
| species' traits help predict small mammal responses to habitat homogenization by an invasive grass. | invasive plants can negatively affect native species, however, the strength, direction, and shape of responses may vary depending on the type of habitat alteration and the natural history of native species. to prioritize conservation of vulnerable species, it is therefore critical to effectively predict species' responses to invasive plants, which may be facilitated by a framework based on species' traits. we studied the population and community responses of small mammals and changes in habitat ... | 2017 | 28317278 |
| low-cost functional plasticity of trpv1 supports heat tolerance in squirrels and camels. | 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 polymoda ... | 2016 | 27638213 |
| structural and functional homologies of the accessory reproductive glands of two species of sciurids, cynomys ludovicianus and citellus tridecemlineatus. | | 1974 | 4418748 |
| presence of a crystal in the cytoplasm of the male germ cells of the garden dormouse eliomys quercinus l. | a crystal is present in the cytoplasm of the male germ cells of a hibernator, the garden dormouse, eliomys quercinus. in another hibernator, the thirteen-lined ground squirrel citellus tridecemlineatus, such crystals were not found. in the garden dormouse, the crystal is present in the cytoplasm of spermatocytes i and ii and of spermatids, after which it is found in the residual bodies. the crystal is usually an ovoid ca 2.4 microns long and 0.75 microns by 1.6 microns when sectioned transversal ... | 1993 | 8402541 |
| enhanced oxidative capacity of ground squirrel brain mitochondria during hibernation. | 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 addr ... | 2017 | 28077389 |
| immunohistochemical organization of the ventral lateral geniculate nucleus in the ground squirrel. | the ventral lateral geniculate nucleus (vlgn) of the thirteen-lined ground squirrel (citellus tridecemlineatus) is a highly differentiated nucleus that is divisible into five major subdivisions on the basis of retinal projections and cytoarchitecture. to pursue the likelihood that these subdivisions (the dorsal cap, intergeniculate leaflet, external magnocellular lamina, internal magnocellular lamina, and parvicellular segment) correlate with the functional diversity of this complex, the present ... | 1992 | 1374767 |
| a reclassification of the genus aplodontopus (acari: sarcoptiformes) with a description of aplodontopus micronyx sp. n. from the thirteen-lined ground squirrel, spermophilus tridecemlineatus, in indiana, usa. | the genus aplodontopus is transferred from the family glycyphagidae to the family chortoglyphidae and a new species aplodontopus micronyx is described. the new species is from the tail-hair follicles of spermophilus tridecemlineatus in indiana, usa; deutonymphs and a female are described. | 1977 | 845722 |
| insight into temperature-dependent microrna function in mammalian hibernators: perspectives on cold-influenced microrna/target interaction. | mammalian hibernation involves re-programming of metabolic functions, in part, facilitated by microrna. although much is known about microrna function, we lack knowledge on low temperature microrna target selection. it is possible that the thermodynamics of microrna target selection could dictate unique temperature-dependent sets of microrna targets for hibernators. | 2017 | 27582076 |
| hif-1α regulation in mammalian hibernators: role of non-coding rna in hif-1α control during torpor in ground squirrels and bats. | a potential role for non-coding rnas, mir-106b and antisense hypoxia inducible transcription factor-1 (hif-1α), in hif-1α regulation during mammalian hibernation was investigated in two species, the thirteen-lined ground squirrel (ictidomys tridecemlineatus) and the little brown bat (myotis lucifugus). both species showed differential regulation of hif-1α during hibernation. hif-1α protein levels increased significantly in skeletal muscle of both species when animals entered torpor, as well as i ... | 2012 | 22526261 |
| sarcocystis campestris from naturally infected 13-lined ground squirrels, spermophilus tridecemlineatus tridecemlineatus, from nebraska. | grossly visible sarcocysts were seen in the skeletal muscles of 1 of 12 13-lined ground squirrels, spermophilus tridecemlineatus tridecemlineatus, collected in nebraska. the tissue cyst wall was up to 5.0 microm thick and contained spikelike projections. transmission electron microscopy of tissue cysts revealed they were similar to sarcocystis campestris cawthorn, wobeser, and gajadhar, 1983, previously known only from experimental infections in richardson's ground squirrel spermophilus richards ... | 2000 | 11128502 |
| transcriptome analysis of spermophilus lateralis and spermophilus tridecemlineatus liver does not suggest the presence of spermophilus-liver-specific reference genes. | the expressions of reference genes used in gene expression studies are assumed to be stable under most circumstances. however, studies had demonstrated that genes assumed to be stably expressed in a species are not necessarily stably expressed in other organisms. this study aims to evaluate the likelihood of genus-specific reference genes for liver using comparable microarray datasets from spermophilus lateralis and spermophilus tridecemlineatus. the coefficient of variance (cv) of each probe wa ... | 2013 | 25937945 |
| ubiquitin conjugate dynamics in the gut and liver of hibernating ground squirrels. | protein synthesis is severely depressed in hibernating mammals. in the absence of significant protein synthesis, the continued turnover of proteins as a function of normal cellular activity would result in the net depletion of protein pools. we measured levels of ubiquitylated proteins in the gut of thirteen-lined ground squirrels ( spermophilus tridecemlineatus) and liver of golden-mantled ground squirrels ( spermophilus lateralis). in both tissues, ubiquitin conjugate concentrations increased ... | 2002 | 11919708 |
| seasonal differences in the testicular transcriptome profile of free-living european beavers (castor fiber l.) determined by the rna-seq method. | the european beaver (castor fiber l.) is an important free-living rodent that inhabits eurasian temperate forests. beavers are often referred to as ecosystem engineers because they create or change existing habitats, enhance biodiversity and prepare the environment for diverse plant and animal species. beavers are protected in most european union countries, but their genomic background remains unknown. in this study, gene expression patterns in beaver testes and the variations in genetic express ... | 2017 | 28678806 |
| hybridization in the mexican and 13-lined ground squirrels, spermophilus mexicanus and spermophilus tridecemlineatus. | evidence of hybridization between the ground squirrels, spermophilus tridecemlineatus and s. mexicanus is presented on the basis of chromosomal and protein data. the hybrids produced appear to be completely interfertile. based on the evidence of hybridization and the recent reestablishment of contact between these two species, they are considered to be semispecies. | 1976 | 950012 |
| multilocus analyses indicate a mosaic distribution of hybrid populations in ground squirrels (genus ictidomys). | dna sequence data from mitochondrial cytochrome-b (cytb) and y-linked structural maintenance of chromosomes (smcy) genes were combined with 478 nuclear loci obtained from amplified fragment length polymorphisms (aflp) to assess the extent of hybridization and genetic spatial structure of populations in two hybridizing species of ground squirrel (ictidomys parvidens and ictidomys tridecemlineatus). based on aflp analyses of 134 individuals from 28 populations, 10 populations were identified that ... | 2013 | 24340186 |
| an improved method for detecting torpor entrance and arousal in a mammalian hibernator using heart rate data. | we used ecg telemeters to measure the heart rate of hibernating ictidomys tridecemlineatus an increase in heart rate from 2.2 to 5 bpm accurately identified arousal from torpor before any change in body temperature was detected. variability in raw heart rate data was significantly reduced by a forward-backward butterworth low-pass filter, allowing for discrete differential analysis. a decrease in filtered heart rate to 70% of maximum values in interbout euthermia (from approximately 312 to 235 b ... | 2018 | 29361606 |
| molecular prerequisites for diminished cold sensitivity in ground squirrels and hamsters. | thirteen-lined ground squirrels and syrian hamsters are known for their ability to withstand cold during hibernation. we found that hibernators exhibit cold tolerance even in the active state. imaging and electrophysiology of squirrel somatosensory neurons reveal a decrease in cold sensitivity of trpm8-expressing cells. characterization of squirrel and hamster trpm8 showed that the channels are chemically activated but exhibit poor activation by cold. cold sensitivity can be re-introduced into s ... | 2017 | 29262313 |
| regulation of pyruvate dehydrogenase (pdh) in the hibernating ground squirrel, (ictidomys tridecemlineatus). | pyruvate dehydrogenase (pdh) is a vital regulatory enzyme that catalyzes the conversion of pyruvate into acetyl-coa and connects anaerobic glycolysis to aerobic tca cycle. post-translational inhibition of pdh activity via three serine phosphorylation sites (ps232, ps293, and ps300) regulate the metabolic flux through the tca cycle, decrease glucose utilization, and facilitate lipid metabolism during times of nutrient deprivation. as metabolic readjustment is necessary to survive hibernation, the ... | 2017 | 29037383 |
| regulation of smad mediated microrna transcriptional response in ground squirrels during hibernation. | mammalian hibernation is a state of dormancy that is used by some animals to survive through the unfavorable conditions of winter, and is characterized by coordinated suppression of basal metabolism that is supported by global inhibition of energy/atp-consuming processes. in this study, we examine the regulation of the anti-proliferatory tgf-β/smad transcription factor signaling pathway in the liver tissue of the hibernating 13-lined ground squirrel ictidomys tridecemlineatus. the tgf-β/smad sig ... | 2017 | 28780752 |
| map kinase signaling and elk1 transcriptional activity in hibernating thirteen-lined ground squirrels. | the thirteen-lined ground squirrel (i. tridecemlineatus) becomes hypometabolic during hibernation; characterized by reductions in energy expensive processes like transcription during periods of low temperature and starvation. we were interested in elucidating the mechanisms of transcriptional control by studying the mapk pathway and downstream transcription factors in skeletal muscle. we were also interested in how environmental factors, such as body temperature, that fluctuate during hibernatio ... | 2017 | 28778486 |
| changes in the phosphoproteome of brown adipose tissue during hibernation in the ground squirrel, ictidomys tridecemlineatus. | mammalian hibernation is characterized by metabolic rate depression and a strong decrease in core body temperature that together create energy savings such that most species do not have to eat over the winter months. brown adipose tissue (bat), a thermogenic tissue that uses uncoupled mitochondrial respiration to generate heat instead of atp, plays a major role in rewarming from deep torpor. in the present study we developed a label-free liquid chromatography mass spectrometry (lc-ms) strategy t ... | 2017 | 28698229 |