Publications

saltbush leaves: excision of hypersaline tissue by a kangaroo rat.	dipodomys microps climbs into shrubs and harvests leaves of the halophyte atriplex confertifolia throughout the year. the epidermal vesicles of these leaves are high in electrolyte concentration, but the specialized photosynthetic parenchyma which is arranged concentrically about the vascular bundles is low in electrolytes and high in starch. the lower incisors of d. microps are broad, flattened anteriorly, and chisel-shaped (unlike those of other kangaroo rats, which are rounded and awl-shaped) ...	1972	17741983
control of a desert-grassland transition by a keystone rodent guild.	twelve years after three species of kangaroo rats (dipodomys spp.) were removed from plots of chihuahuan desert shrub habitat, density of tall perennial and annual grasses had increased approximately threefold and rodent species typical of arid grassland had colonized. these were just the most recent and drmatic in a series of changes in plants and animals caused by experimental exclusion of dipodomys. in this ecosystem kangaroo rats are a keystone guild: through seed predation and soil disturba ...	1990	17734708
behavioural syndromes in merriam's kangaroo rats (dipodomys merriami): a test of competing hypotheses.	behavioural syndromes, correlations of behaviours conceptually analogous to personalities, have been a topic of recent attention due to their potential to explain trade-offs in behavioural responses, apparently maladaptive behaviour and limits to plasticity. using merriam's kangaroo rats (dipodomys merriami), we assessed the explanatory power and generality of hypothesized syndrome structures derived from the literature and the natural history of the species. several aspects of functionally dist ...	2007	17623643
evidence for the mode of action of the highly cytotoxic streptomyces polyketide kendomycin.	the macrocyclic polyketide kendomycin exhibits antiosteoporotic and antibacterial activity, as well as strong cytotoxicity against multiple human tumor cell lines. despite the promise of this compound in several therapeutic areas, the cellular target(s) of kendomycin have not been identified to date. we have used a number of approaches, including microscopy, proteomics, and bioinformatics, to investigate the mode of action of kendomycin in mammalian cell cultures. in response to kendomycin treat ...	2007	17592829
recent demographic bottlenecks are not accompanied by a genetic signature in banner-tailed kangaroo rats (dipodomys spectabilis).	single-sample methods of bottleneck detection are now routine analyses in studies of wild populations and conservation genetics. three common approaches to bottleneck detection are the heterozygosity excess, mode-shift, and m-ratio tests. empirical groundtruthing of these methods is difficult, but their performances are critical for the accurate reconstruction of population demography. we use two banner-tailed kangaroo rat (dipodomys spectabilis) populations from southeastern arizona (usa) that ...	2007	17561905
scaling of elastic energy storage in mammalian limb tendons: do small mammals really lose out?	it is widely believed that elastic energy storage is more important in the locomotion of larger mammals. this is based on: (a) comparison of kangaroos with the smaller kangaroo rat; and (b) calculations that predict that the capacity for elastic energy storage relative to body mass increases with size. here we argue that: (i) data from kangaroos and kangaroo rats cannot be generalized to other mammals; (ii) the elastic energy storage capacity relative to body mass is not indicative of the import ...	2005	17148127
sylvatic maintenance of borrelia burgdorferi (spirochaetales) in northern california: untangling the web of transmission.	lyme borreliosis is associated with several genospecies of borrelia burgdorferi sensu lato (s.l.) (spirochaetales), but human disease has been associated only with borrelia burgdorferi sensu stricto (s.s.) johnson, schmid, hyde, steigerwalt & brenner in the western united states. restriction fragment length polymorphism (rflp) analysis of rrf-rrl amplicons from 124 tick and mammalian isolates from various habitats yielded 13 rflp patterns. of these patterns, six were patterns previously associat ...	2006	16892634
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
parentage analysis detects cryptic precapture dispersal in a philopatric rodent.	locating birthplaces using genetic parentage determination can increase the precision and accuracy with which animal dispersal patterns are established. we re-analyse patterns of movement away from the birthplace as a function of time, sex and population density for a sample of 303 banner-tailed kangaroo rats, dipodomys spectabilis. we located birth sites using a combination of likelihood-based parentage analysis with live-trapping of mothers during the breeding season. the results demonstrate t ...	2006	16689908
short interspersed elements (sines) of the geomyoidea superfamily rodents.	a new short interspersed element (sine) was isolated from the genome of desert kangaroo rat (dipodomys deserti) using single-primer pcr. this sine consists of two monomers: the left monomer (idl) resembles rodent id element and other trnaala(cgc)-derived sines, whereas the right one (geo) shows no similarity with known sine sequences. pcr and hybridization analyses demonstrated that idl-geo sine is restricted to the rodent superfamily geomyoidea (families geomyidea and heteromyidea). isolation a ...	2006	16517098
evolution of the spermatozoon in muroid rodents.	in the rodent superfamily muroidea, a model for the evolution of sperm form has been proposed in which it is suggested that a hook-shaped sperm head and long tail evolved from a more simple, nonhooked head and short tail in several different subfamilies. to test this model the shape of the sperm head, with particular emphasis on its apical region, and length of sperm tail were matched to a recent phylogeny based on the nucleotide sequence of several protein-coding nuclear genes from 3 families a ...	2005	16037955
cache decision making: the effects of competition on cache decisions in merriam's kangaroo rat (dipodomys merriami).	caching food is an economic, decision-making process that requires animals to take many factors into account, including the risk of pilferage. however, little is known about how food-storing animals determine the risk of pilferage. in this study, the authors examined the effect of a dominant competitor species on the caching and behavior of merriam's kangaroo rat (dipodomys merriami). the authors found that, as with conspecific competitors, kangaroo rats did not alter caching in response to the ...	2005	15982162
western gray squirrel (rodentia: sciuridae): a primary reservoir host of borrelia burgdorferi in californian oak woodlands?	in california, dense woodlands have been recognized as important biotopes where humans are exposed to the nymphal stage of the western blacklegged tick, ixodes pacificus cooley & kohls, the primary vector of the lyme disease spirochete borrelia burgdorferi sensu stricto (s.s.), in the far-western united states. to identify the principal reservoir host(s) of this spirochete, and of closely related spirochetes in the b. burgdorferi sensu lato (s.l.) complex, in dense woodlands in mendocino county, ...	2005	15962792
using a probabilistic approach in an ecological risk assessment simulation tool: test case for depleted uranium (du).	a probabilistic approach was applied in an ecological risk assessment (era) to characterize risk and address uncertainty employing monte carlo simulations for assessing parameter and risk probabilistic distributions. this simulation tool (era) includes a window's based interface, an interactive and modifiable database management system (dbms) that addresses a food web at trophic levels, and a comprehensive evaluation of exposure pathways. to illustrate this model, ecological risks from depleted ...	2005	15910910
direct calorimetry reveals large errors in respirometric estimates of energy expenditure.	knowledge of animal energetics is based largely upon indirect calorimetry, which is estimation of metabolic heat production by an organism from measurement of indices such as oxygen consumption or carbon dioxide production. remarkably, indirect calorimetry has been validated by comparison to direct measurements of metabolic heat production (direct calorimetry) only for highly restricted conditions, primarily with a few species of medium-to-large mammals. taxa with differing physiologies are litt ...	2005	15767305
do kangaroo rats thrive when drinking sea water?		1950	15410478
effects of high sodium diet and of high potassium diet on the adrenals and kidney of the desert kangaroo rat and domestic albino rat.		1949	15407706
effects of trichloroethylene and perchloroethylene on wild rodents at edwards air force base, california, usa.	effects of inhalation of volatilized trichloroethylene (tce) or perchloroethylene (pce) were assessed based on the health and population size of wild, burrowing mammals at edwards air force base (ca, usa). organic soil-vapor concentrations were measured at three sites with aquifer contamination of tce or pce of 5.5 to 77 mg/l and at two uncontaminated reference sites. population estimates of kangaroo rats (dipodomys merriami and d. panamintinus) as well as hematology, blood chemistry, and histop ...	2004	15378993
membrane organization and function of m1 and m23 isoforms of aquaporin-4 in epithelial cells.	aquaporin-4 (aqp4) water channels exist as heterotetramers of m1 and m23 splice variants and appear to be present in orthogonal arrays of intramembraneous particles (oaps) visualized by freeze-fracture microscopy. we report that aqp4 forms oaps in rat gastric parietal cells but not in parietal cells from the mouse or kangaroo rat. furthermore, the organization of principal cell oaps in brattleboro rat kidney is perturbed by vasopressin (arginine vasopressin). membranes of llc-pk(1) cells express ...	2004	15149973
[effect of laminin on structural karyotype variability of kangaroo rat kidney cell lines].	the structural karyotypic variability has been investigated in the "markerless" epithelial-like rat kangaroo kidney cell lines nbl-3-17 and nbl-3-11 on cultivation on a laminin-2/4 coated surface. in cell line nbl-3-17, cultivated on the laminin-coated surface for 2, 4 and 12 days, and in cell line nbl-3-11, cultivated on the laminin-coated surface for 2 and 4 days, there is a significant increase in the frequency of chromosomal aberrations, both chromosomal breaks and dicentrics (telomeric asso ...	2003	14989178
[effect of laminin on numerical karyotype variability of kangaroo rat kidney cell lines].	the numerical karyotypic variability has been investigated in "markerless" epithelial-like rat kangaroo kidney cell lines nbl-3-11 and nbl-3-17 on cultivation on a laminin-2/4 coated surface. in cell line nbl-3-17, cultivated on the laminin-coated surface for 2, 4 and 12 days, the character of numerical karyotypic variability has changed. in 2 days the general character of cell distribution for the chromosome number did not change, but the frequency of cells with modal number of chromosomes decr ...	2003	14989177
respiratory characteristics of kangaroo rat blood.		1952	14907822
a complete account of the water metabolism in kangaroo rats and an experimental verification.		1951	14897858
antidiuretic hormone in the urine and pituitary of the kangaroo rat.		1950	14808277
low-frequency distortion product otoacoustic emissions in two species of kangaroo rats: implications for auditory sensitivity.	low-frequency distortion-product otoacoustic emissions were measured in two species of kangaroo rats to test the prediction that a large footdrumming species (e.g., dipodomys spectabilis) would have greater distortion-product otoacoustic emission amplitude than a small non-footdrumming species (e.g., dipodomys merriami), indicating better hearing sensitivity at low frequencies. equal-level (65 db spl) stimulus tones ( f(1), f(2)), presented over a ( f(1)) range of 200-1000 hz, were used to evoke ...	2004	14648101
effectiveness of six species of rodents as dispersers of singleleaf piñon pine (pinus monophylla).	the effectiveness of six species of rodents as dispersers of singleleaf piñon pine (pinus monophylla) was investigated in field enclosures. the rodent species were panamint kangaroo rat (dipodomys panamintinus), great basin pocket mouse (perognathus parvus), pinyon mouse (peromyscus truei), deer mouse (peromyscus maniculatus), least chipmunk (tamias minimus), and white-tailed antelope ground squirrel (ammospermophilus leucurus). five measures of seed harvesting and caching behavior were assessed ...	2004	14534782
specific subtotal labyrinthectomy in the kangaroo rat. i. right lateral semicircular canal: procedure and effects.		1959	14407076
response of the kangaroo rat (dipodomys merriami mearns) to single whole-body x-irradation.		1960	14398991
urea excretion in white rats and kangaroo rats as influenced by excitement and by diet.		1955	14376584
experimental usefulness of the kangaroo rat.		1964	14141924
the ear apparatus of the kangaroo rat, dipodomys.		1961	14005478
two new fleas (hystrichopsyllidae) from the kangaroo rat and pocket mouse.		1960	13819081
growth and development of merriam's kangaroo rat, dipodomys merriami.		1959	13809779
evaporative water loss of small vertebrates, as measured with an infrared analyzer.	evaporation is linearly and inversely related to absolute humidity at 26 degrees to 27 degrees c. the relative rate of loss in desert reptiles, rodents, and anurans is about 1:10:40. the maximum rate of water loss is about 2.5 and 5 times the basal rate, respectively, in pocket mice and sand lizards. the ratio of loss from lung to loss from skin is about 84:16 in kangaroo rats and 70:30 in rattlesnakes.	1961	13692977
a comparative study of growth and development of the kangaroo rats, dipodomys deserti stephens and dipodomy's merriami mearns.		1961	13689478
the dorsal holocrine skin gland of the kangaroo rat (dipodomys).		1954	13189137
excretion of endogenous and exogenous creatinine and of mannitol in the kangaroo rat.		1954	13180735
electrophysiological studies of ear of kangaroo rat (dipodomys).		1954	13163717
merriam's kangaroo rats (dipodomys merriami) voluntarily select temperatures that conserve energy rather than water.	desert endotherms such as merriam's kangaroo rat (dipodomys merriami) use both behavioral and physiological means to conserve energy and water. the energy and water needs of kangaroo rats are affected by their thermal environment. animals that choose temperatures within their thermoneutral zone (tnz) minimize energy expenditure but may impair water balance because the ratio of water loss to water gain is high. at temperatures below the tnz, water balance may be improved because animals generate ...	2003	13130431
the histology of the kidney of kangaroo rats.		1952	13016983
renal tubular excretion of urea in kangaroo rats.		1952	12985862
effect of predation risk on selectivity in heteromyid rodents.	variations in predation risk affect the costs of foraging and may therefore warrant different foraging decisions. one class of models ("higher requisite profit") predicts that foragers should become more selective when predation risk increases, as low-profitability items that do not cover the increased costs are dropped from the diet. an alternative class of models ("reduced finickiness") predicts that foragers should become less selective when predation risk increases, because selectivity requi ...	2003	12914997
gene dispersal and outbreeding in a philopatric mammal.	extensive mark-recapture data from banner-tailed kangaroo rats, dipodomys spectabilis, have shown that both males and females are highly philopatric and suggest the possibility of close inbreeding. however, indirect analyses based on genetic structure appear to contradict direct observations, suggesting longer dispersal distances. using microsatellite genotypes from most members of a banner-tailed kangaroo rat population during five successive breeding seasons, we ask how relatedness is influenc ...	2003	12859643
how does the ecological foraging behavior of desert kangaroo rats (dipodomys deserti) relate to their behavior on radial mazes?	experiment 1 showed that laboratory-reared desert kangaroo rats, like domestic norway rats, efficiently search for food on a radial arm maze (ram) by avoiding revisiting arms within a trial. by placing an ram on the floor so the animals could approach food from any direction, experiment 2 tested whether efficient search by kangaroo rats was based on tactics of distance minimizing, central-place foraging, trail following, or meandering. in contrast to the dominant trail-following tactic of domest ...	2002	12593326
the effects of thyroxine on metabolism and water balance in a desert-dwelling rodent, merriam's kangaroo rat (dipodomys merriami).	desert-dwelling mammals such as merriam's kangaroo rat (dipodomys merriani) need to conserve both energy and water to survive desert conditions characterized by aridity and low productivity. the thyroid hormone thyroxine increases both basal metabolic rate and urinary water loss in mammals. increases in basal metabolism and urinary water loss are likely to be detrimental to d. merriami, therefore the regulation of this hormone may be important. to examine the effects of thyroxine in this species ...	2002	11824400
real-time monitoring of intracellular mrna hybridization inside single living cells.	a molecular beacon, an oligonucleotide probe with inherent signal transduction mechanisms, is an optimal tool for visualizing real-time mrna hybridization in single living cells. each molecular beacon (mb) consists of a single-stranded dna molecule in a stem-loop conformation with a fluorophore linked to the 5' end and a quencher at the 3' end. in this study, we demonstrate real-time monitoring of mrna-dna hybridization inside living cells using molecular beacons. a mb specific for beta-actin mr ...	2001	11816586
developmental and acclimatory contributions to water loss in a desert rodent: investigating the time course of adaptive change.	understanding the evolution of physiological traits requires considering three nonexclusive mechanisms that underlie phenotypes and cause their change over different time scales: acclimation, developmental plasticity, and natural selection for genetically fixed traits. physiological adjustments to changes in the desiccating potential of the environment were investigated with one subspecies of common desert rodent, dipodomys merriami merriami (merriam's kangaroo rat). we raised young whose parent ...	2001	11765976
integration of genotoxic and population genetic endpoints in biomonitoring and risk assessment.	genetic ecotoxicology is a multifaceted discipline that examines the effects of xenobiotic compounds on the structure and function of dna. this paper discusses the role of genetic ecotoxicology in environmental biomonitoring and risk assessment. genetic ecotoxicology may include somatic effects (e.g., dna damage) or population genetic effects (changes in genetic diversity or gene frequencies). traditionally, genetic ecotoxicology studies have focused on either one of these sub-disciplines, but i ...	2001	11501436
geographic patterns of genetic differentiation within the restricted range of the endangered stephens' kangaroo rat dipodomys stephensi.	using mtdna variation in the kangaroo rat dipodomys stephensi, we found no support for the hypothesis that a species with an historically restricted range will exhibit low levels of genetic polymorphism and little genetic structure. dipodomys stephensi has long been restricted to a few interior coastal valleys in southern california encompassing an area of approximately 70 x 40 km; however, we found high levels of genetic variation over much of its range and significant genetic structure both wi ...	2001	11475059
length control of primary cilia: analysis of monociliate and multiciliate ptk1 cells.	lengths of primary cilia in cultured ptk1 cells, on both a population basis and within individual (multiciliate) cells, have been compared. the latter examines the degree of discrepancy between cilia arising within the same cell and using a common precursor pool, on the hypothesis that a better correlation would be expected between cilia issuing from the same centrosome than between those in the population in general. to obtain accurate et plentiful measurements, a 'flow-fixation' technique was ...	2000	11374436
integration of genotoxicity and population genetic analyses in kangaroo rats (dipodomys merriami) exposed to radionuclide contamination at the nevada test site, usa.	we examined effects of radionuclide exposure at two atomic blast sites on kangaroo rats (dipodomys merriami) at the nevada test site, nevada, usa, using genotoxicity and population genetic analyses. we assessed chromosome damage by micronucleus and flow cytometric assays and genetic variation by randomly amplified polymorphic dna (rapd) and mitochondrial dna (mtdna) analyses. the rapd analysis showed no population structure, but mtdna exhibited differentiation among and within populations. genot ...	2001	11351431
delayed compensation for missing keystone species by colonization.	because individual species can play key roles, the loss of species through extinction or their gain through colonization can cause major changes in ecosystems. for almost 20 years after kangaroo rats were experimentally removed from a chihuahuan desert ecosystem in the united states, other rodent species were unable to compensate and use the available resources. this changed abruptly in 1995, when an alien species of pocket mouse colonized the ecosystem, used most of the available resources, and ...	2001	11292873
absence of aquaporin-4 water channels from kidneys of the desert rodent dipodomys merriami merriami.	recently, we found that aquaporin-4 (aqp4) is expressed in the s3 segment of renal proximal tubules of mice but not in rat proximal tubules. because mice have relatively larger papillae than rats, it was proposed that the renal distribution of aqp4 in various species could be related to their maximum urinary concentrating ability. therefore, kidneys and other tissues of merriam's desert kangaroo rat, dipodomys merriami merriami, which produce extremely concentrated urine (up to 5,000 mosmol/kgh( ...	2001	11292621
urea excretion in white rats and kangaroo rats as influenced by excitement and by diet.	reprinted from the american journal of physiology, vol. 181, no.1, april, 1955.	2001	11274249
unappreciated tolerance to high ambient temperatures in a widely distributed desert rodent, dipodomys merriami.	a long-held assertion has been that nocturnality is an escape mechanism for many nocturnal desert rodents because of limited tolerances to heat. to test this claim, we used a treadmill to examine the tolerances to high ambient temperatures (t(a)'s) of one subspecies of desert rodent, merriam's kangaroo rat, dipodomys merriami merriami, from contrasting environments. we simultaneously measured body temperature (t(b)), evaporative water loss, and metabolic rates at an ecologically relevant speed ( ...	2000	11121354
fractionation and characterization of satellite dnas of the kangaroo rat (dipodomys ordii).	nuclear dna from liver cells of the kangaroo rat species dipodomysordii was fractionated and characterized with the aid of buoyant density gradients in neutral and alkaline cscl and in ag(+)-cs(2)so(4). more than one-half of the dna was present in three density satellites, a greater proportion than in any other species yet reported; the purified satellite dnas were denser than principal dna. all satellite fractions revealed sharp isopycnic bands and narrow denaturation profiles. two had identica ...	1974	10793740
characterization of microsatellite loci in bannertailed and giant kangaroo rats, dipodomys spectabilis and dipodomys ingens.		2000	10792713
prevalence of cutaneous evaporation in merriam's kangaroo rat and its adaptive variation at the subspecific level.	previous estimates suggested that ventilatory evaporation constitutes the major source of water loss in kangaroo rats (dipodomys spp.). we quantified rates of water loss in merriam's kangaroo rat (dipodomys merriami) and demonstrate the degree to which acclimation to a particular thermal and hydric environment plays a role in the intraspecific variation in water loss evident in this species. we draw the following conclusions: (1) that water loss varies intraspecifically in merriam's kangaroo rat ...	2000	10648219
life history of ixodes (ixodes) jellisoni (acari: ixodidae) and its vector competence for borrelia burgdorferi sensu lato.	ixodes (ixodes) jellisoni cooley & kohls, a nonhuman biting and little known tick, is one of 4 members of the i. ricinus complex in the united states. a localized population of i. jellisoni inhabiting a grassland biotope in mendocino county, ca, was studied from 1993 to 1997. rodent trapping in all seasons revealed that the only host of both immature and adult i. jellisoni was the heteromyid rodent dipodomys californicus merriam. field investigations suggested that i. jellisoni is nidicolous in ...	1999	10337104
comparative morphometry of mammalian central auditory systems: variation in nuclei and form of the ascending system.	the volumes of the ten largest subcortical auditory nuclei were measured individually in a sample of 53 mammals, including 16 australian and four american marsupials. the nuclear sizes relative to the total of subcortical auditory tissue were normalized and then analyzed individually for statistically reliable deviations. the overall form of the entire system of ten nuclei and two nuclear sub-systems (cochlear nuclei, superior olives) were also analyzed for similarities and notable deviations am ...	1998	9491274
small mammal survival and trapability in mark-recapture monitoring programs for hantavirus.	following the 1993 hantavirus pulmonary syndrome (hps) epidemic in the south-western united states, mammalogists and epidemiologists instituted long-term studies to monitor population density and prevalence of infection in rodents which constitute the reservoir for sin nombre virus (snv). in this study, field techniques used in sampling small mammals for snv infection were evaluated to determine if trapping and handling protocols were having significant effects on future trapability or mortality ...	1998	9476220
maternal presence and rearing condition affect responses to a live predator in kangaroo rats (dipodomys heermanni arenae).	experiment 1 compared the responses of wild-caught adult and captive-born adult and juvenile kangaroo rats (dipodomys heermanni arenae) to a live snake. wild-caught adult rats were less active and monitored the snake more than during a control condition; captive-born juvenile rats did not behave differently during snake and control tests. snake-naive adult rats behaved more like the wild-caught adult rats, but not on all measures. in experiment 2, pups were tested at 25 and 50 days of age in 4 c ...	1997	9419881
species-specific footdrumming in kangaroo rats: dipodomys ingens, d. deserti, d. spectabilis	footdrumming was compared in three allopatric species of kangaroo rat, dipodomysfrom three habitats. analysis of footdrumming recordings revealed species-specific patterns of drumming ranging from single thumps to individual footdrumming signatures. the desert kangaroo rat, d. desertidrums single thumps spaced 0.25-0.30 s apart that are sometimes introduced with a short footroll. the giant kangaroo rat, d. ingensdrums long footrolls that can average over 100 drums at 18 drums/s. the banner-taile ...	1997	9398370
seismic communication between the burrows of kangaroo rats, dipodomys spectabilis.	banner-tailed kangaroo rats, dipodomys spectabilis, footdrum to produce substrate-borne and airborne acoustic energy. previous studies show that they communicate territorial ownership via airborne footdrumming signals. the research reported here used simulated footdrum patterns generated by an artificial 'thumper' to address the question of whether kangaroo rats communicate through seismic components of these acoustic signals. with microphones suspended in sealed burrows, we found that airborne ...	1997	9373957
hemorrhagic gastritis in free-living rodents in idaho.	between february 1992 and march 1994, four species of rodent from the snake river birds of prey area near boise, idaho (usa) were necropsied. hemorrhagic gastritis was observed in 16 of 131 townsend's ground squirrels (spermophilus townsendii), one of 11 ord's kangaroo rats (dipodomys ordii) and the one great basin pocket mouse (perognathus parvus) evaluated. no lesions were observed in 14 white-footed deer mice (peromyscus maniculatus). tissue from one townsend's ground squirrel was negative fo ...	1996	9359067
genome composition in venezuelan spiny-rats of the genus proechimys(rodentia, echimyidae). i. genome size, c-heterochromatin and repetitive dnas in situ hybridization patterns.	the genome sizes of the venezuelan spiny-rats proechimys guairae guairae (2n = 48) and p. trinitatis (2n = 62) were evaluated and proved to be 12.5 +/- 0.5 pg and 12.6 +/- 0.3 pg respectively, the highest so far recorded among mammals; also the c-heterochromatin (32.7%, coefficient of variation [cv] 3.8 and 35.8%, cv 4.4) and gc (44.2%, cv 2.7 and 43.6%, cv 2.9) contents are very high. highly repetitive (rep) dnas were isolated from restriction enzyme digested genomic dnas of both species. the i ...	1997	9345903
botfly (diptera:oestridae) parasitism of ord's kangaroo rats (dipodomys ordii) at suffield national wildlife area, alberta, canada.	during field study of ord's kangaroo rat (dipodomys ordii) at suffield national wildlife area, alberta, canada, a high prevalence of parasitism by botfly (diptera: oestridae) larvae was observed. botflies have not previously been documented as parasites of kangaroo rats. botfly parasitism could have a significant impact on the growth, survival, and reproduction of ord's kangaroo rat, which is considered a vulnerable species in canada. therefore, it is important to investigate how botfly parasiti ...	1997	9267398
polyclonal antibodies against human gamma-tubulin stain centrioles in mammalian cells from different tissues.	rabbit polyclonal antibodies were raised against the c-terminal fragment (amino acid residues 318-451) of human gamma-tubulin. these antibodies were used to stain cultured cells of various tissues (epithelium, nervous tissue, fibroblasts) from different animals (human, monkey, pig, rat, kangaroo rat, mouse, hamster, chicken, triton). the antibodies specifically stained centrioles in the interphase and mitotic cells of mammals, but not birds (chicken) or amphibians (newt). in the interphase cells ...	1997	9225254
kangaroo rats exhibit spongiform degeneration of the central auditory system similar to that found in gerbils.	kangaroo rats develop spongiform degeneration of the central auditory system similar to that seen in the gerbil. light microscopic and transmission electron microscopic study of the cochlear nucleus and auditory nerve root (anr) of dipodomys deserti and d. merriami show that spongiform lesions develop in dendrites and oligodendrocytes of the cochlear nucleus and in oligodendrocytes of the anr that are morphologically indistinguishable from those extensively described in the mongolian gerbil, mer ...	1997	9119769
sound-power collection by the auditory periphery of the mongolian gerbil meriones unguiculatus: iii. effect of variations in middle-ear volume.	the effects of variations in middle-ear cavity size on hearing sensitivity in the mongolian gerbil are predicted by computing the effect on acoustic power input to the middle ear. acoustic power collection from a diffuse sound field was computed from measurements of the middle-ear input impedance and external-ear radiation impedance and mathematical models of the middle and external ear presented in the first two papers of this series [j. acoust. soc. am. 92, 157-177 (1992); j. acoust. soc. am. ...	1997	9104016
[the genotoxic effect of ciprofloxacin on cultured cells from the kangaroo rat kidney and on skin fibroblasts from the indian muntjac].	the genotoxicity of an antibiotic ciprofloxacin (cf) in doses of 10, 25, 50 and 100 mkg/ml under its short-term (6-48 h) and long-term (15-30 days) action on sublines of rat kangaroo kidney, nbl-3-11, and indian muntjak skin fibroblasts has been studied. the emergence of genotoxic effect depends on the dose and time of ciprofloxacin action on both the sublines, but the degree of this effect does not depend on these parameters directly. ciprofloxacin exerts no influence on cell distribution for c ...	1996	9019897
gastric trichobezoar in a banner-tailed kangaroo rat (dipodomys spectabilis).	a male, wild-caught kangaroo rat developed anorexia and wasting. the animal was euthanized and a gastric trichobezoar found at necropsy. the paucity of information regarding the clinical medicine of this species is a hindrance to those charged with the care of kangaroo rats. gastric trichobezoar should be considered as a differential diagnosis in cases of anorexia in kangaroo rats.	1996	8938627
no sex difference occurs in hippocampus, food-storing, or memory for food caches in black-capped chickadees.	a number of recent studies have described sex differences in the relative size of the hippocampus that are associated with sex differences in the use of space. voles, kangaroo rats, and cowbirds all exhibit a sex difference in relative size of the hippocampal formation that is correlated with a sex difference in spatial behaviour. we wished to determine whether sex differences in the size of the hippocampus occur in the absence of a difference in the use of space, and whether the previously desc ...	1996	8883812
[the effect of the mycoplasma contamination of 2 kidney cell sublines from the kangaroo rat on their karyotypic structure].	the karyotypic variability has been investigated for two cell sublines of rat kangaroo kidney cultured for 40-160 days after contamination with acholeplasma laidlawii, strain pg-8. the contaminated cultures did not differ from non-contaminated ones in cell distribution for chromosome number. the majority of cells of subline nbl-3-11 with modal number of chromosomes displayed the main structural variant of the karyotype (svk)--2+2+2+2+2+1; in subline nbl-3-17 the main svk being 3+3+3+3+3+2. a com ...	1996	8768552
kangaroo rat bone compared to white rat bone after short-term disuse and exercise.	kangaroo rats (dipodomys ordii) were used to study the effects of confinement on mechanical properties of bone with a long range objective of proposing an alternative to the white rat model for the study of disuse osteoporosis. kangaroo rats exhibit bipedal locomotion, which subjects their limbs to substantial accelerative forces in addition to the normal stress of weight bearing. we subjected groups of kangaroo rats and white rats (rattus norvegicus) to one of two confinement treatments or to a ...	1996	8759284
elastic and length-force characteristics of the gastrocnemius of the hopping mouse (notomys alexis) and the rat (rattus norvegicus).	the aim of this study was to compare the contractile and series elastic properties of terrestrial mammals that use bipedal versus quadrupedal gaits. the gastrocnemius muscle of the hopping mouse (body mass 30.2 +/- 2.4 g, mean +/- s.d.) and the rat (313 +/- 10.7 g) were compared with data from the literature for the wallaby and the kangaroo rat to distinguish scaling effects and locomotion-related effects on muscle properties. contractile length-force properties and series elastic stiffness were ...	1996	8691113
ixodes (ixodes) jellisoni and i. (i.) neotomae (acari:ixodidae): descriptions of the immature stages from california.	nymphal and larval stages of ixodes (ixodes) jellisoni cooley & kohls and i. (i.) neotomae cooley are described for the first time. these 2 tick species occur only in the western united states, predominantly in california. the primary host for i. jellisoni is the california kangaroo rat, dipodomys californicus (merriam); that for i. neotomae is the dusky-footed woodrat, neotoma fuscipes baird. the etiologic agent of lyme disease borrelia burgdorferi johnson, schmidt, hyde, steigerwalt & brenner ...	1996	8667376
reservoir competence of four chaparral-dwelling rodents for borrelia burgdorferi in california.	aspects of the reservoir competence of four rodents for the lyme disease spirochete, borrelia burgdorferi, were evaluated in california. rodents were live-trapped and ear-punch biopsies were cultured during each season. a second set of biopsies was cultured from representative individuals after 2-3 weeks of captivity and the results of culturing biopsies taken on both dates were compared with the results of feeding ixodes pacificus larvae on hosts xenodiagnostically. the prevalence of infections ...	1996	8651378
fleas (siphonaptera) infesting giant kangaroo rats (dipodomys ingens) on the elkhorn and carrizo plains, san luis obispo county, california.	the giant kangaroo rat, dipodomys ingens (merriam), has a limited distribution in the san joaquin valley, ca. because of reductions in its geographic range, largely resulting from humans, the species was listed as an endangered species in 1980 by the california fish and game commission. as part of a study of the community ecology of southern california endangered species, including d. ingens, we were able to make flea collections from the rats when they were trapped and marked for population stu ...	1993	8433341
spongistatin 1, a highly cytotoxic, sponge-derived, marine natural product that inhibits mitosis, microtubule assembly, and the binding of vinblastine to tubulin.	a highly cytotoxic macrocyclic lactone polyether has been isolated from a spongia species and named spongistatin 1. with l1210 murine leukemia cells an ic50 value for cell proliferation of 20 pm was obtained, and an increase in the mitotic index concordant with the decrease in cell number was observed. kangaroo rat kidney ptk1 cells were examined by indirect immunofluorescence with a spongistatin 1 concentration that caused 50% reduction in cellular protein (0.3 nm) and with a 10-fold higher con ...	1993	8232226
hearing in prairie dogs: transition between surface and subterranean rodents.	behavioral audiograms were determined for four black-tailed and one white-tailed prairie dogs (cynomys ludovicianus and c. leucurus) using a conditioned avoidance procedure. the hearing of black-tailed prairie dogs ranges from 29 hz to 26 khz and that of the white-tailed prairie dog from 44 hz to 26 khz (at sound pressure levels of 60 db). both species have good low-frequency hearing, especially black-tailed prairie dogs which can hear as low as 4 hz and are more sensitive than any other rodent ...	1994	8188546
spatial memory in the desert kangaroo rat (dipodomys deserti).	desert kangaroo rats (dipodomys deserti) forage for seed distributed in patches in the desert environment and may remember patch locations. in experiment 1, 7 desert kangaroo rats that had discovered the location of a plastic token in 1 box accurately dug for a token hidden in the same location in a 2nd identical box. results of experiment 2 indicated that the rats primarily remembered the spatial location of the token within the box in relation to extramaze objects and the walls of the experime ...	1994	8174344
natural space-use patterns and hippocampal size in kangaroo rats.	the size of the hippocampus, a forebrain structure that processes spatial information, correlates with the need to relocate food caches by passerine birds and with sex-specific patterns of space use in microtine rodents. the influences on hippocampal anatomy of sexual selection within species, and natural selection between species, have not yet been studied in concert, however. here we report that natural space-use patterns predict hippocampal size within and between two species of kangaroo rats ...	1994	7987661
genetic diversity among borrelia burgdorferi isolates from wood rats and kangaroo rats in california.	twenty-nine borrelia burgdorferi isolates, obtained from dusky-footed wood rats (neotoma fuscipes) and california kangaroo rats (dipodomys californicus) in california, were analyzed genetically. chromosomal dna was examined by restriction endonuclease analysis (rea) and gene probe restriction fragment length polymorphism. pulsed-field gel electrophoresis was used to analyze the plasmid profiles of the isolates. rea, the method with the greatest discrimination, disclosed 24 distinct restriction p ...	1993	7905880
recruitment of antigenic gamma-tubulin during mitosis in animal cells: presence of gamma-tubulin in the mitotic spindle.	it has been claimed repeatedly that gamma-tubulin is exclusively localized at the spindle poles in mitotic animal cells, where it plays a role in microtubule nucleation. in addition to this localization, we have observed a gamma-tubulin-specific staining of the mitotic spindle in several animal cells (human, kangaroo rat, mouse, chinese hamster, xenopus and drosophila) using five polyclonal antibodies raised against unique gamma-tubulin sequences and four different fixation protocols. in hela an ...	1994	7876350
effects of competition, colonization, and extinction on rodent species diversity.	analyses of long-term experimental data from the chihuahuan desert revealed that species diversity of other rodents was higher on plots from which kangaroo rats (dipodomys spp.) had been removed. the difference was due to consistently higher colonization and lower extinction probabilities of small granivorous rodents in the absence of competitively dominant kangaroo rats. the results of this ecosystem experiment demonstrate the importance of both competitive exclusion and metapopulation dynamics ...	1995	7846530
ultrastructure of pinealocytes of the kangaroo rat (dipodomys ordi).	the ultrastructure of the pinealocytes of the wild-captured ord kangaroo rat (dipodomys ordi) was examined. a homogeneous population of pinealocytes was present in the pineal gland of the kangaroo rat. the golgi apparatus, granular endoplasmic reticulum, mitochondria, lysosomes, dense-core vesicles, vacuoles containing a flocculent material and lipid droplets were consistent components of the pinealocyte cytoplasm, whereas infrequently-observed organelles included centrioles, multivesicular bodi ...	1982	7127418
coccidia from kangaroo rats (dipodomys spp.) in the western united states, baja california, and northern mexico with descriptions of eimeria merriami sp. n. and isospora sp.		1983	6827438
hormonal regulation of sandbathing in male kangaroo rats (dipodomys merriami).	detection of reproductive status from chemical signals at sandbathing loci was examined in merriam's kangaroo rat. castrated and intact males were attracted similarly to the sandbathing loci of four classes of scent donors: intact males, castrated males, estrous females, and nonestrous females. this suggested that reproductive status was not communicated to males at sandbathing loci. in a control test, castrated males were attracted to disturbed sand that contained no olfactory cues whereas inta ...	1983	6626088
changes in the thermal characteristics of hypothalamic neurons during sleep and wakefulness.	the characteristics of the mammalian thermoregulatory system are dependent upon arousal state. during nrem sleep thermoregulatory mechanisms are intact but body temperature is regulated at a lower level than during wakefulness. in rem sleep thermoregulatory effector mechanisms are inhibited and thermal homeostasis is severely disrupted. thermosensitivity of neurons in the preoptic/anterior hypothalamus (poah) was determined for behaving kangaroo rats (dipodomys deserti) during electrophysiologic ...	1984	6488008
postpartum and lactational estrus: a comparative analysis in rodentia.	virgin rodents exhibiting cycling estrus have traditionally been used for comparative studies of reproductive behavior. however estrus occurs in other life-history contexts, some of which differ from cycling estrus (ce) in that (a) the female is disposed to behave both maternally and sexually and (b) they result in litter overlap (i.e., the simultaneous gestation and lactation of two litters). in this report, two of these other modes of estrus are examined, with emphasis on their evolutionary an ...	1984	6478785
the red function of phage lambda mediates the alteration of an interspersed repeated dna sequence from the kangaroo rat dipodomys ordii.	the kangaroo rat d. ordii is shown to contain an interspersed repeated sequence 3.25 kb in length. this sequence undergoes alteration (deletions) when cloned into a red+ lambda vector but is stable in a red- vector. using the red- clone it is shown that deletions are the result of the activity of the lambda red, or e. coli rece, recombination systems. mixed infection experiments demonstrate that this activity is acting in trans. the deletions appear to yield fragments of specific size, suggestin ...	1982	6294479
the distribution of angiotensin ii binding sites in rodent brain.	the distribution of specific angiotensin ii (aii) binding capacity of several brain regions, pituitary, and adrenals was determined in 6 rodent species namely rats, mice, hamsters, kangaroo rats, gerbils and degus. rats and mice had similar distributions with the highest levels of binding observed in the area postrema, septum and superior colliculi. low levels were seen in the cortex, cerebellum, striatum and hippocampus. other areas had intermediate levels. the distribution of aii binding in ge ...	1981	6258713
the 500 hz frequency-following potential in kangaroo rat: an evaluation with noise masking.	this study on kangaroo rat has shown that the volume-conducted 500 hz ffp can be recorded at stimulus levels which are near behavioral threshold. the response is a complex, double-peaked wave form, indicating that multiple brain stem sources are involved in its generation. the ffp wave form changes in a complex manner with intensity. recordings of the ffp in the presence of broadband noise demonstrate that the response is neural in origin at suprathreshold stimulus levels. the various configurat ...	1980	6155254
seasonal variation in various blood indices of the kangaroo rat, dipodomys panamintinus.	1. various blood indices in the panamint kangaroo rat revealed seasonal fluctuations. the red blood cell count during winter and summer averaged 7.2 +/- 1.0 x 10(6) and 9.2 +/- 0.2 x 10(6)/mm3 respectively. 2. the mean cell hemoglobin during winter and summer averaged 25 +/- 10.8 pg and 18.6 +/- 3.7 pg respectively. 3. these fluctuations may reveal a rapid rate of red blood cell destruction during winter in combination with a change in diet, concomitant to this, is an increase in mean cell hemog ...	1982	6121650
eimeria scholtysecki n. sp. from ord's kangaroo rat dipodomys ordii.		1967	6038029
specific subtotal labyrinthectomy of the superior semicircular canals of the kangaroo rat.		1967	6034493
natural free-running period in vertebrate animal populations.	regression analysis (analysis of covariance) is contrasted with the conventional "mean period length" for estimating the length of period of the spontaneous activity frequency (free-running period) in population samples of gila monsters (heloderma suspectum) and kangaroo rats (dipodomys merriami) in the sonoran desert. the mean period length in each population does not differ significantly from 24:00 hours (p > .05) and it does not differ significantly (p > .05) between the species studied; the ...	1967	6021681
a hermaphroditic kangaroo rat.		1965	5891271
the ultrastructure of the placental labyrinth in the kangaroo rat, dipodomys.		1969	5776881