| genetics reveal the origin and timing of a cryptic insular introduction of muskrats in north america. | the muskrat, ondatra zibethicus, is a semiaquatic rodent native to north america that has become a highly successful invader across europe, asia, and south america. it can inflict ecological and economic damage on wetland systems outside of its native range. anecdotal evidence suggests that, in the early 1900s, a population of muskrats was introduced to the isles of shoals archipelago, located within the gulf of maine, for the purposes of fur harvest. however, because muskrats are native to the ... | 2014 | 25360617 |
| seasonal expression of androgen receptor in scented gland of muskrat (ondatra zibethicus). | muskrat is a seasonal breeder, males of which secret musk from paired perineal scented glands found beneath the skin at the ventral base of the tail for attracting female during the breeding season. the aim of this study was to investigate the seasonal changes of expression of androgen receptor (ar) in the scented gland of muskrat during the breeding and nonbreeding seasons. histologically, glandular cells, interstitial cells and excretory tubules were identified in scented glands in both season ... | 2014 | 24818970 |
| long-term morphogenetic aftereffects of muskrat acclimatization in western siberia. | | 2014 | 24795185 |
| [the omsk hemorrhagic fever: research results (1946-2013)]. | the main aspects of epidemiology and epizootology of the omsk hemorrhagic fever (ohf) are analyzed. the discovery of the virus ohf in 1947, as well as the first outbreak of new diseases in the districts of the omsk region, is described. comprehensive work for decryption of the etiology of the ohf by specialists from the omsk and moscow institutes is carried out. long-term dynamics of activity of natural foci of ohf contains four periods of variable intensity of epidemic and epizootic processes. ... | 2014 | 25929029 |
| effects of structural connectivity on fine scale population genetic structure of muskrat, ondatra zibethicus. | in heterogeneous landscapes, physical barriers and loss of structural connectivity have been shown to reduce gene flow and therefore lead to population structuring. in this study, we assessed the influence of landscape features on population genetic structure and gene flow of a semiaquatic species, the muskrat. a total of 97 muskrats were sampled from three watersheds near sudbury, ontario, canada. we estimated population genetic structure using 11 microsatellite loci and identified a single gen ... | 2013 | 24223287 |
| fecal coliform removal in a lightly loaded surface-flow constructed treatment wetland polishing agricultural runoff. | constructed treatment wetlands can be an effective and sustainable method to remove pathogens that pose health risks from agricultural runoff. this study evaluated the removal of fecal coliform (fc) from agricultural runoff in a lightly loaded surface-flow treatment wetland prior to discharge to the yakima river, washington state, usa. the 1.6 ha system consisted of a sedimentation basin (1.4 d hydraulic retention time) followed by two wetlands (5-6 d hydraulic retention time). fc in inflow rang ... | 2013 | 23985523 |
| distribution of rodenticide resistance and zoonotic pathogens in norway rats in lower saxony and hamburg, germany. | genetically based resistance to anticoagulants has led to increasing difficulties in the control of rodents over recent decades. the possible impact of rodenticide-resistant rats on the infection risk of humans and livestock by zoonotic pathogens is generally unknown. hence, in a monitoring programme in the german federal states of lower saxony and hamburg, more than 500 norway rats were analysed for both tyr139cys polymorphisms within the vkorc1 gene and zoonotic agents. | 2013 | 22888034 |
| revealing cryptic parasite diversity in a definitive host: echinostomes in muskrats. | many trematode groups have a long history of systematic revision, which can make parasite identification a difficult task. the trematode parasites of muskrats are no exception. here, we highlight the systematic issues associated with trematodes of muskrats (ondatra zibethicus). then, we demonstrate the utility of using both morphological and molecular tools to identify these parasites. morphological examinations of specimens from muskrats (n = 63) first suggested that at least 4 genera were pres ... | 2012 | 22694483 |
| animal models for investigating the central control of the mammalian diving response. | pioneering studies by per scholander indicated that the diving response consists of reflexly induced apnea, bradycardia and an alteration of blood flow that maintains perfusion of the heart and brain. more recently field physiological studies have shown that many marine animals can adjust cardiorespiratory aspects of their diving response depending upon the behavioral situation. this could suggest that the very labile heart rate during diving is under direct cortical control. however, the final ... | 2012 | 22661956 |
| a simultaneous test of synchrony causal factors in muskrat and mink fur returns at different scales across canada. | synchrony among populations has been attributed to three major hypotheses: dispersal, the moran effect, and trophic-level interactions. unfortunately, simultaneous testing of these hypotheses demands complete and detailed data, which are scarce for ecological systems. | 2011 | 22102919 |
| immunolocalization of androgen receptor, aromatase cytochrome p450, estrogen receptor alpha and estrogen receptor beta proteins during the breeding season in scent glands of muskrats (ondatra zibethicus). | aromatase cytochrome p450 (p450arom) is an enzyme that catalyzes the conversion of androgen to estrogen. expression of p450arom in extra-gonadal sites and locally-synthesized estrogen play an important role in physiological conditions. the purpose of this study was to investigate the cellular immunolocalization of androgen receptor (ar), p450arom, estrogen receptor alpha (era) and estrogen receptor beta (erβ) in muskrat scent glands during the breeding season. histological observation and immuno ... | 2011 | 21967219 |
| genetic structure of muskrat (ondatra zibethicus) and its concordance with taxonomy in north america. | extrinsic factors such as physical barriers play an important role in shaping population genetic structure. a reduction in gene flow leading to population structuring may ultimately lead to population divergence. these divergent populations are often considered subspecies. because genetic differentiation may represent differences between subspecies, patterns of genetic structure should reflect subspecies groupings. in this study, we examine the contemporary population genetic structure of muskra ... | 2011 | 21810770 |
| hematologic and blood chemistry reference values for free-ranging muskrats (ondatra zibethicus). | baseline hematologic and serum chemistry values are used by veterinarians and wildlife biologists to identify abnormally high or low levels of particular blood parameters in a target species. this vital information can assist animal care providers in making informed decisions on the care of wildlife and help to determine diagnoses for certain illnesses. published blood parameter values are not available for wild-caught muskrats (ondatra zibethicus). we measured 27 blood parameter values from 29 ... | 2011 | 21719833 |
| [ulcerating nodules on the right arm after hunting muskrats]. | | 2011 | 21609403 |
| immunolocalization of inhibin/activin subunit proteins during the breeding season in testes and scented glands of muskrats (ondatra zibethicus). | the objective of this study was to investigate the cellular immunolocalization of inhibin a and inhibin/activin (β(a) and β(b)) subunits in the muskrat testes and scented glands during the breeding season. inhibin α and inhibin/activin (β(a) and β(b)) subunits were expressed in sertoli cells and leydig cells of testes and glandular cells of scented glands, respectively. also, positive signals of inhibin α and inhibin/activin (β(a) and β(b)) subunits by western blotting were both observed in test ... | 2011 | 21532261 |
| prevalence of giardia and cryptosporidium in muskrats in northeastern pennsylvania and new jersey. | giardia spp. and cryptosporidium spp. are intestinal parasites that affect humans and animals throughout the world. although infection with giardia spp. is usually self-limiting, some cases result in mild to severe enteritis. giardiasis can be treated with modern drugs. the increasing incidence of well-documented outbreaks of cryptosporidiosis has resulted in a growing awareness of the danger of this infection. in this study, the authors examined beavers and muskrats to determine their role as r ... | 2009 | 19408429 |
| isolation and characterization of polymorphic microsatellite loci in muskrat, ondatra zibethicus. | we describe the isolation and characterization of 12 highly polymorphic microsatellite loci for the muskrat, ondatra zibethicus. microsatellite markers from three other rodent species were cross-amplified in muskrat and one of them was polymorphic. we observed moderate to high levels of genetic variability in these 13 polymorphic loci (five to 22 alleles per locus) with observed heterozygosity ranging from 0.48 to 0.96. these markers will be useful for further studies on population genetic struc ... | 2009 | 21564719 |
| [hypoxic factors influence on chronotropic heart reactions of ondatra ondatra zibethicus in free behavior]. | | 2016 | 16944818 |
| body cooling and the diving capabilities of muskrats (ondatra zibethicus): a test of the adaptive hypothermia hypothesis. | we tested the hypothesis that immersion hypothermia enhances the diving capabilities of adult and juvenile muskrats by reducing rates of oxygen consumption (v o2). declines in abdominal body temperature (t(b)) comparable to those observed in nature (0.5-3.5 degrees c) were induced by pre-chilling animals in 6 degrees c water. pre-chilling did not reduce diving v o2 of any animal tested in 10 degrees c or 30 degrees c water, irrespective of the nature of the dive. most behavioural indices of dive ... | 2006 | 16626985 |
| smoothing for spatiotemporal models and its application to modeling muskrat-mink interaction. | for a set of spatially dependent dynamical models, we propose a method for estimating parameters that control temporal dynamics by spatial smoothing. the new approach is particularly relevant for analyzing spatially distributed panels of short time series. the asymptotic results show that spatial smoothing will improve the estimation in the presence of nugget effect, even when the sample size in each location is large. the proposed methodology is used to analyze the annual mink and muskrat data ... | 2003 | 14969459 |
| diving experience and the aerobic dive capacity of muskrats: does training produce a better diver? | we tested the hypothesis that the body oxygen stores, aerobic dive limit (adl) and dive performance of muskrats can be enhanced by dive-conditioning in a laboratory setting. we compared several key variables in 12 muskrats trained to swim a 16 m underwater course to a feeding station ('divers') with those of 12 animals precluded from diving but required to travel identical distances in water to feed ('surface swimmers'). acclimated muskrats assigned to each group were trained concurrently over a ... | 2003 | 12604575 |
| reconstruction of biogeographic and evolutionary networks using reticulograms. | a reticulogram is a general network capable of representing a reticulate evolutionary structure. it is particularly useful for portraying relationships among organisms that may be related in a nonunique way to their common ancestor - relationships that cannot be represented by a dendrogram or a phylogenetic tree. we propose a new method for constructing reticulograms that represent a given distance matrix. reticulate evolution applies first to phylogenetic problems; it has been found in nature, ... | 2002 | 12028728 |
| polycyclic aromatic hydrocarbon metabolites in the bile of a territorial benthic fish, oyster toadfish (opsanus tau) from the elizabeth river, virginia. | reverse-phase high-performance liquid chromatographic analyses of bile of a territorial benthic fish, oyster toadfish (opsanus tau), indicated that fish from reference stations in the york and elizabeth rivers, virginia, contained lower concentrations of polycyclic aromatic hydrocarbon (pah) metabolites than fish from polluted stations. pah metabolite levels in the bile of fish from mildly polluted stations were 7 to 10 times greater than those from reference stations. pah metabolite levels in f ... | 2002 | 11706367 |
| phase coupling and synchrony in the spatiotemporal dynamics of muskrat and mink populations across canada. | population ecologists have traditionally focused on the patterns and causes of population variation in the temporal domain for which a substantial body of practical analytic techniques have been developed. more recently, numerous studies have documented how populations may fluctuate synchronously over large spatial areas; analyses of such spatially extended time-series have started to provide additional clues regarding the causes of these population fluctuations and explanations for their synchr ... | 2001 | 11606729 |
| body oxygen stores, aerobic dive limits, and the diving abilities of juvenile and adult muskrats (ondatra zibethicus). | intraspecific variability in body oxygen reserves, muscle buffering capacity, diving metabolic rate, and diving behavior were examined in recently captured juvenile and adult muskrats. allometric scaling exponents for lung (b=1.04), blood (b=0.91), and total body oxygen storage capacity (b=1.09) did not differ from unity. the concentration of skeletal muscle myoglobin scaled positively with mass in 254-600-g juveniles (b=1.63) but was mass-independent in larger individuals. scaling exponents for ... | 2006 | 11247737 |
| common structure in panels of short ecological time-series. | typically, in many studies in ecology, epidemiology, biomedicine and others, we are confronted with panels of short time-series of which we are interested in obtaining a biologically meaningful grouping. here, we propose a bootstrap approach to test whether the regression functions or the variances of the error terms in a family of stochastic regression models are the same. our general setting includes panels of time-series models as a special case. we rigorously justify the use of the test by i ... | 2000 | 11133038 |
| sarcoma of possible nerve sheath origin in a captive muskrat. | a captive adult female muskrat (ondatra zibethicus) was found dead without previous signs of disease. at necropsy, abdominal organs were infiltrated with a poorly demarcated, soft, tan tissue. microscopically this tissue was composed of neoplastic cells assuming two distinct growth characteristics consistent with antoni a and b patterns. ultrastructurally, the neoplastic cells were pleomorphic, lacked junctional devices, had abundant mitochondria and ergastoplasm, and frequently were closely ass ... | 2000 | 10941748 |
| effects of immigration on some stochastic logistic models: a cumulant truncation analysis. | this paper uses a new cumulant truncation methodology to investigate the stochastic power law logistic model with immigration, and illustrates the model with parameter values used to describe the growth of muskrat populations in the netherlands. this model has a stable equilibrium distribution. the incorporation of immigration into the model, therefore, simplifies the qualitative nature of the stochastic solution. the (unconditional) cumulant functions for the transient and the equilibrium popul ... | 1999 | 10544066 |
| [the resistance of the muskrat ondatra zibethicus to hypoxic exposures during diving]. | | 2016 | 10519205 |
| electrical stimulation of the anterior ethmoidal nerve produces the diving response. | stimulation of the upper respiratory tract usually produces apnea, but it can also produce a vagally mediated bradycardia and a sympathetically mediated increase in peripheral vascular resistance. this cardiorespiratory response, often called the diving response, is usually initiated by nasal stimulation. the purpose of this research was to investigate the anterior ethmoidal nerve (aen) that innervates the nasal mucosa of muskrats (ondatra zibethicus). electrical stimulation of the aen (typicall ... | 1999 | 10350556 |
| [nematode and trematode fauna of the muskrat (ondatra zibethicus link, 1795) in lower saxony]. | from january 1995 to december 1995, 991 muskrats were examined for the occurrence and the regional prevalence of nematodes and trematodes. the muskrats were trapped in all parts of lower saxony. 77.2% of the studied population were less than one year old, 22.8% were older. the male to female ratio was 54.5% to 45.5%. one genus of nematodes, trichuris spp., was found in the colon in 1.9% of the animals in the south of the investigated area. a species differentiation was not possible, as exclusive ... | 1997 | 9451855 |
| fos immunohistochemical determination of brainstem neuronal activation in the muskrat after nasal stimulation. | stimulation of the nasal passages of muskrats with either ammonia vapours or retrogradely-flowing water produced cardiorespiratory responses (an immediate 62% decrease in heart rate, 29% increase in mean arterial blood pressure, and sustained expiratory apnoea). we used the immunohistological detection of fos, the protein product of the c-fos gene, as a marker of neuronal activation to help elucidate the brainstem circuitry of this cardiorespiratory response. after repeated ammonia stimulation o ... | 1997 | 9153669 |
| urea recycling in muskrats (ondatra zibethicus): a potential nitrogen-conserving tactic? | the rate of 14c-urea hydrolysis was determined in 32 field-acclimatized muskrats maintained on natural diets during spring, summer, fall, and winter. we hypothesized that urea recycling occurs in muskrats during all seasons and that the conservation of tissue nitrogen via this mechanism is most prevalent in fall and winter, when forage protein levels are lowest. muskrats exhibited higher rates of urea hydrolysis and a lower serum urea nitrogen-to-creatinine ratio in fall and winter than in sprin ... | 2013 | 9231395 |
| field immobilization of muskrats (ondatra zibethicus) for minor surgical procedures. | a combination of ketamine hydrochloride and xylazine hydrochloride at doses of 50 mg/kg and 5 mg/kg, respectively, was used to immobilize 48 muskrats (ondatra zibethicus) from october 1993 to november 1994 in tennessee (usa). mean (+/-sd) time for induction was 2.97 +/- 1.1 min. after a mean (+/-sd) duration of 27.2 +/- 3.5 min intramuscular yohimbine hydrochloride at a dose of 0.125 mg/kg was administered. mean (+/-sd) recovery time was 48.1 +/- 21.6 min. all anesthetic inductions were smooth a ... | 1997 | 9027708 |
| brainstem origin of preganglionic cardiac motoneurons in the muskrat. | the muskrat, and aquatic rodent with a brisk and reliable diving response, shows a remarkable bradycardia after nasal stimulation. however, the medullary origin of cardiac preganglionic motoneurons is unknown in this species. we injected fat pads near the base of the heart of muskrats with a wga-hrp solution to label retrogradely preganglionic parasympathetic neurons that project to the cardiac plexi. results showed that the preponderance of labeled neurons was in ventrolateral parts of the medu ... | 1996 | 8955533 |
| possible contamination of surface waters with giardia spp. through muskrats. | muskrats were examined for giardia infections. collected faecal samples were processed by means of sucrose density gradient centrifugation, using a 1 m sucrose solution. identification of cysts was done by phase contrast microscopy, by the immunofluorescence test, or by both methods. from july 1994 to september 1995, a total of 234 muskrats from two different geographical areas in western parts of germany were examined for the presence of giardia cysts. 176 animals (75.2%) were found to be giard ... | 1996 | 8837391 |
| autonomic nervous control of heart rate in muskrats during exercise in air and under water. | neural control of the cardiac responses to exercise in air (running) and under water (diving) was studied in the muskrat (ondatra zibethicus) by means of acute pharmacological blockade with the muscarinic blocker atropine and the beta-adrenergic blocker nadolol. saline injection was used as a control. controls running on a treadmill showed a marked increase in heart rate with exercise. atropine-treated animals had a higher resting heart rate than controls, but heart rate still increased with run ... | 1996 | 8699158 |
| [a dynamic study of the count of a commercial muskrat population (ondatra zibethica: mammalia) in a simulation model]. | density-dependent mechanisms of muskrat numbers regulation in karakalpakstan were investigated by mathematical imitation model. the behaviour of model and native population is quite similar. the upper limit for optimum level of density under given conditions is determined by exogenous factors. within population mechanisms lead the density and population structure to the level suitable for given conditions. | 2006 | 8967163 |
| immobilization of muskrats (ondatra zibethicus) with ketamine and xylazine. | the effectiveness of ketamine and xylazine as an immobilizing combination for muskrats (ondatra zibethicus) was evaluated. eleven muskrats were intramuscularly injected using a high (n = 7) or low (n = 4) dosage of a 20:1 mixture of ketamine (12 or 20 mg) and xylazine (0.6 or 1.0 mg) in carlton county, minnesota (usa) from 1 to 4 may 1995. mean (+/- sd) induction times for muskrats receiving a high dosage (6.5 +/- 2.6 min) or low dosage (7.0 +/- 1.6 min) was similar (p = 0.71). in contrast, musk ... | 1996 | 8627930 |
| effect of pharmacological blockade on cardiovascular responses to voluntary and forced diving in muskrats. | neural control of free and forced diving bradycardia and peripheral resistance was studied in the muskrat (ondatra zibethicus) by means of acute pharmacological blockade with the muscarinic blocker atropine, the alpha-adrenergic blocker phentolamine and the beta-adrenergic blockers nadolol and propranolol. saline injection was used as a control. heart rate in control animals increased before voluntary dives and dropped markedly as soon as the animals submerged. heart rate started increasing towa ... | 1995 | 7490569 |
| isoflurane as an inhalation anesthetic for muskrats (ondatra zibethicus). | the effectiveness of isoflurane as an inhalation anesthetic for muskrats (ondatra zibethicus) was evaluated. thirty muskrats were anesthetized in an enclosed chamber using 10 ml of isoflurane in carlton county, minnesota (usa), from 27 september to 24 october 1994. mean (+/- se) induction time for adults, juveniles, and kits was 20.6 +/- 2.9, 21.5 +/- 2.4, and 16.9 +/- 5.3 min, respectively (p = 0.77). respective mean arousal times for adults, juveniles, and kits were 5.1 +/- 0.5, 5.7 +/- 0.7, a ... | 1995 | 8592396 |
| a medullary dorsal horn relay for the cardiorespiratory responses evoked by stimulation of the nasal mucosa in the muskrat ondatra zibethicus: evidence for excitatory amino acid transmission. | stimulation of the upper respiratory tract, including the nasal mucosa, with water, vaporous irritants, or gases, induces a collation of several cardiorespiratory responses including an apnea and bradycardia and often some change in arterial blood pressure. since the nasal mucosa is innervated by branches of the trigeminal nerve, it implies that some part of the trigeminal system within the central nervous system mediates the autonomic responses induced by nasal stimulation. in the present study ... | 1995 | 8590063 |
| [the ultrastructure of the cerebral cortex in the muskrat ondatra zibethica in high-altitude hypoxia]. | | 2006 | 8779291 |
| postnatal growth and development in semi-captive muskrats, ondatra zibethicus. | we studied postnatal growth and preweaning development of muskrats under semicaptive conditions in a temperate environment. the principal objectives were to quantify weaning age and investigate potential effects of sex and parturition date on growth rate. we also tested a previous hypothesis that juvenile muskrats inhabiting temperate environments exhibit a winter growth diapause. developmental attributes varied significantly among 6 litters (n = 31 individuals), except for age at eye opening (m ... | 1995 | 8770609 |
| [assessment of the effect of endogenous and exogenous factors on multiplication of productive populations of muskrats]. | | 1994 | 8054879 |
| heat increment of feeding and its thermoregulatory benefit in the muskrat (ondatra zibethicus). | the calorigenic effect of feeding and its potential benefit in defraying thermoregulatory costs and attenuating immersion hypothermia of adult muskrats were investigated. a single session of feeding on aquatic vegetation was sufficient to raise the metabolic rate of muskrats for a period of at least 5 h. the peak postprandial rate of oxygen consumption averaged 1.42 times the level established for fasted animals, and the heat increment of feeding accounted for about 40% of the metabolizable ener ... | 1994 | 8056880 |
| muskrat populations in virginia's elizabeth river: physiological condition and accumulation of environmental contaminants. | this study evaluated the physiological condition and environmental contaminant concentrations in muskrats inhabiting the contaminated lower region of the elizabeth river, virginia, (usa). muskrats trapped in the lower region of the elizabeth river weighed less, had lower mean fat indexes, lower relative spleen weights, greater relative adrenal weights, and an increased incidence of disease and parasitism compared to muskrats trapped in the less contaminated upper region of the elizabeth river or ... | 1993 | 8239713 |
| hepatic capillariasis in muskrats (ondatra zibethicus). | we present the first prevalence data of hepatic capillariasis in muskrats in pennsylvania and connecticut (usa). the prevalence of hepatic capillariasis in five groups of muskrats coming from different locations and numbering 81, 229, 11, 19, and 20 animals, was 42%, 78%, 36%, 16%, and 0%, respectively. liver lesions varied from minimal to severe multifocal granulomatous hepatitis, often containing adult worms or eggs. | 1993 | 8355364 |
| use of dna fingerprinting to determine parentage in muskrats (ondatra zibethicus). | the detection of high levels of genetic variability by dna fingerprinting probes has allowed researchers to accurately assess relatedness. multiple-mating strategies are characteristic of the mating systems of small mammals. as such, techniques that provide an accurate indication of how individuals are related genetically is of great importance to assess the mating system of a species. in this study, we applied the dna fingerprinting technique to captive and wild muskrats (ondatra zibethicus) to ... | 2006 | 1401879 |
| [the electrical activity of the neocortical neurons of muskrats in hypoxia]. | | 1991 | 1668664 |
| trigeminal mediation of the diving response in the muskrat. | stimulation of the nasal cavity elicits powerful cardiorespiratory responses similar to the diving response. in the present study, bradycardia and apnea were elicited in muskrats by stimulation of the nasal cavity with ammonia vapors. these responses could be blocked by injections of 2% lidocaine made bilaterally into the medullary dorsal horns of the trigeminal sensory complex. however, the bradycardia due to activation of the baroreceptor reflex with intravenous phenylephrine was retained. the ... | 1991 | 1760738 |
| stereotaxic atlas of the brainstem of the muskrat, ondatra zibethicus. | the muskrat is an aquatic rodent of moderate size and possesses dramatic respiratory and cardiovascular behaviors in response to submersion, stimulation of the upper respiratory tract, or environmental cues. this report provides a stereotaxic atlas of the muskrat's brainstem in the transverse plane to facilitate studies requiring an accurate localization of discrete brain structures. plates are presented of brainstem sections between the obex and superior colliculus separated by 450 microns. eac ... | 1991 | 1868351 |
| density-dependent habitat selection in muskrats: a test of the ideal free distribution model. | two predictions of the ideal free distribution model, a null hypothesis of habitat selection, were examined using free-ranging muskrats. we rejected the prediction that the proportion of the animals found in each of five habitats was independent of population size. data on over-winter occupancy of muskrat dwellings tend also to refute the prediction of equal fitness reward among habitats. habitat type and water-level had a profound effect on the suitability of a site for settlement. we concluded ... | 1990 | 28313029 |
| controlled bradycardia induced by nasal stimulation in the muskrat, ondatra zibethicus. | respiration was disrupted and bradycardia induced in anesthetized muskrats by stimulating the nasal cavity with a stream of either water or various concentrations of ammonia vapors. when responses induced by either ammonia or water were compared, ammonia vapors were considered preferable because the responses could be maintained reliably through relatively rapid periods of stimulation, and the post-stimulus recovery of heart rate and respiration was more predictable. moreover, the bradycardia in ... | 1990 | 2229892 |
| prevalence of giardia spp. in beaver and muskrat populations in northeastern states and minnesota: detection of intestinal trophozoites at necropsy provides greater sensitivity than detection of cysts in fecal samples. | surveys of the prevalence of the intestinal protozoan giardia spp. in animal populations have relied almost exclusively on the detection of cysts in fecal samples. we have determined the prevalence of giardia spp. in beaver and muskrat populations in four northeastern states and minnesota by using both the detection of trophozoites in mucosal scrapings from live-trapped animals at necropsy and the detection of cysts in fecal samples collected from kill-trapped animals. in muskrats the prevalence ... | 1990 | 2178552 |
| the muskrat in biomedical research. | muskrats are aquatic rodents of moderate size which are plentiful throughout north america, but are not used commonly in the laboratory. recently, we tested the feasibility of muskrats as experimental models and have found them to be acquired and cared for easily in conventional laboratory animal facilities. some of their natural characteristics and diseases are described. the husbandry techniques that we used are presented and form a base for the preparation of future guidelines for the mainten ... | 1988 | 3065574 |
| [arterial vascularization of the intestine of the muskrat (ondatra zibethicus)]. | | 1988 | 3052171 |
| arterial blood supply to the stomach of the muskrat (ondatra zibethicus). | | 1988 | 3291640 |
| male-biased reproduction and sex-ratio adjustment in muskrats. | sex ratios of a population and of litters were sampled in muskrats in ontario, canada. sex ratios of litters sampled from nests were male biased (54% male). until weaning, no differential costs of producing and rearing male and female young were identified that could account for this greater production of males. following weaning, however, male-biased dispersal of juveniles from their natal site and more frequent acquisition by females of these sites as breeding sites the following year suggeste ... | 1988 | 28311755 |
| [parasites in east germany. 8. helminths of ondatra zibethica]. | in 1984/85 80 muskrats have been investigated by helminthological autopsy. helminth infection was established in 72 animals. altogether 4 trematodes, 7 cestodes and 2 nematodes were found. 2 cestodes were detected for the first time in the muskrat. relations between parasite fauna and biotope are recognizable. | 1987 | 3300434 |
| [intermediate host of the trematode quinqueserialis quinqueserialis (trematoda, notocotylidae) in the ussr and the morphology of its parthenitae and larvae]. | a high infection rate of muskrat with the trematode q. quinqueserialis was recorded in pribaikalje. its intermediate host is the mollusc gyraulus (anisus) stroemi. morphology and biology of parthenites and larval phases of the development are studied and characters of the biology of this trematode are found out. | 2007 | 3528992 |
| effects of co2 inhalation on acid-base balance and thermal recovery following cold water dives by the muskrat (ondatra zibethicus). | thermoregulatory, cardiac, and blood gas responses of muskrats to co2 inhalation were examined during recovery from controlled dives in 3 degrees c water. it was shown that co2 levels previously recorded in the winter lodges of this species are sufficient to reduce postdive oxygen consumption and rate of rewarming in unrestrained animals. postdive exposure to 5-10% co2 reduced recovery of abdominal and subcutaneous temperature (tb) in the middorsal lumbar region, but did not affect interscapular ... | 1986 | 3088072 |
| responses of wild muskrats (ondatra zibethicus l.) to scented traps. | free-ranging muskrats were trapped in scented and blank traps in new york state at local ponds during all seasons and at a wildlife refuge in spring and early summer. in a total of 4839 trap-nights, 65 muskrats were caught. trapping success was 1.34%. the overall responses to differently scented traps differed significantly. adults preferentially entered blank and food-baited traps, whereas young showed no preference to blank, musk, or control odor. it appears that adults actively avoid musk, es ... | 1984 | 24317592 |
| oxygen and carbon dioxide transport in the blood of the muskrat (ondatra zibethica). | we have investigated the oxygen and carbon dioxide transport properties of a small diving mammal, the muskrat (ondatra zibethica), where the hemoglobin primary structure has been established by duffy et al. (1978). while whole blood oxygen capacity, the haldane effect and the buffer capacity are not different compared to non-diving mammals of similar size, the bohr effect and the oxygen affinity are increased. the oxygen half saturation pressure (p50) was 26.1 mm hg (3.5 kpa) at ph 7.4, and the ... | 1984 | 6435225 |
| [experimental animal information file: chromosomes of muskrats (suncus murinus)]. | | 1984 | 6375576 |
| mechanics, power output and efficiency of the swimming muskrat (ondatra zibethicus). | the surface swimming of muskrats (ondatra zibethicus linnaeus) was studied by forcing individual animals to swim against a constant water current, of velocity ranging from 0.2 to 0.75 m s-1, in a recirculating water channel. lateral and ventral views of the swimming muskrats were filmed simultaneously for analysis of thrust by the propulsive appendages. drag measurements and flow visualization on dead muskrats demonstrated that these animals experience large resistive forces due to the formation ... | 1984 | 6379093 |
| [experimental animal information file: muskrats (suncus murinus)]. | | 1983 | 6349547 |
| metabolic effects of swimming velocity and water temperature in the muskrat (ondatra zibethicus). | metabolic rates, vo2, were studied in four muskrats (ondatra zibethicus) swimming in a water channel at velocities of 0.2 to 0.75 m/s in water at temperatures of 25 and 30 degrees c. at both water temperatures, vo2 increased linearly with increasing swimming velocity. the vo2 was higher for muskrats swimming in water at 25 than 30 degrees c. the metabolic performance of swimming appears to be influenced by the interaction of swimming velocity and water temperature. | 1983 | 6136374 |
| [quantity of foods, weight of anatomic structures and body weight in the muskrat (ondatra zibethicus, l., 1766)]. | weights of skeletons, several viscera (heart, lungs, empty stomach and intestine, liver, spleen, kidneys) and muscles of 80 muskrats were taken. the data were analyzed and compared versus four classes of ages and sexes: adult males, adult females, sub-adult males and sub-adult females. the weight of the muscles is 47 to 50% of the live-weight in the four classes studied. the weight of the viscera is approximately 10 to 12% of the live-weight. thus, the weight of edible matters varies, in the mus ... | 1982 | 6758070 |
| terminal dives in mink, muskrat and beaver. | monitoring of eeg, ekg and overt behavior of mink, muskrat, and beaver caught in leg hold traps in an aquatic tank, showed marked differences by species. death by co2 induced narcosis (submersion asphyxia) was evident in beaver, about 50 percent of muskrat but "wet" drowning occurred in mink. bradycardia was evident in all three species but was most pronounced in the beaver. times to cessation of struggle, brain activity and heart activity indicated that the terminal dives of mink and muskrat, b ... | 1982 | 7048357 |
| tyzzer's disease in muskrats: re-examination of specimens of hemorrhagic disease collected by paul errington. | organisms typical of those seen in tyzzer's disease of muskrats (ondatra zibethica) were found in tissue sections from two muskrats found dead in iowa in 1947 by paul errington. these findings support further the hypothesis that errington's and tyzzer's diseases of muskrats are a single entity. | 1979 | 522221 |
| the initiation and maintenance of bradycardia in a diving mammal, the muskrat, ondatra zibethica. | 1. the cardiac and respiratory responses shown by muskrats in both unrestrained and restrained dives have been compared with responses elicited by stimulation of a number of cardio-depressant receptor inputs, in an attempt to determine which are most important in initiating and maintaining diving bradycardia. 2. in unrestrained voluntary dives heart rate fell from 310 +/- 3 to 54 +/- 3 beats min-1 in 1 to 2 sec, which was significantly below that seen in dives by restrained unanaesthetized or an ... | 1979 | 469759 |
| reduction of aquatic vegetation following the colonization of a northern swedish lake by the muskrat, ondatra zibethica. | the muskrat (ondatra zibethica (l.)) utilizes emergent hydrophytes both for housebuilding and for food. the impact of these activities on stands of equisetum fluviatile l. in a northern swedish lake was investigated. the areas of open water created by the muskrats were estimated from infrared air photographs, taken in july, on three occasions during a five-year period. during the first three years, with low muskrat densities, the areas of open water were estimated to represent removal of about o ... | 1979 | 28309074 |
| climatic variability and body size variation in the muskrats (ondatra zibethicus) of north america. | patterns of geographic variation in nine morphological characters of adult muskrats (ondatra zibethicus) are investigated by multiple regression and canonical correlation analysis. three variables describing the annual precipitation regimen account for 16 to 33% of the variance in each of the skeletal measurements. highly variable precipitation patterns result in low rates of germination and survivorship for preferred aquatic food plants which in turn reduces average total food availability for ... | 1978 | 28309223 |
| energy metabolism of oiled muskrats. | | 1974 | 4420701 |
| role of environment in the population dynamics of the muskrat in yakutia. | | 1974 | 4825908 |
| the muskrat as reservoir in natural foci of adiaspiromycosis. | | 1974 | 4836175 |
| [muskrat--a natural carrier of toxoplasma]. | | 1973 | 4204005 |
| synhimantus (nematoda) associated with gastric squamous tumors in muskrats. | | 1968 | 5689986 |
| initiation of diving bradycardia in muskrats. | | 1972 | 5033459 |
| occurrence of some helminth parasites in the muskrat, ondatra zibethicus, from crawford county, kansas. | | 1972 | 4667884 |
| seasonal metabolic organization in the muskrat (ondatra zibethica). i. changes in growth, thyroid activity, brown adipose tissue, and organ weights in nature. | | 1971 | 5113544 |
| [characteristics of the adrenergic apparatus of adipose tissue in muskrat mammary glands]. | | 1971 | 5153366 |
| [non-icteric leptospirosis associated with water contaminated by muskrats]. | | 1969 | 5392893 |
| [the afferent innervation of muskrat mammary glands]. | | 1969 | 5404177 |
| the mitotic and meiotic chromosomes of the muskrat (ondatra zibethica l.). | | 1969 | 5354236 |
| the effect of protein intake on maximum urine and renal tissue water-solute concentrations in the muskrat (ondatra zibethica osoyoosensis, lord). | | 1968 | 5758863 |
| [leptospirosis among muskrats in the primorsk region]. | | 1968 | 5735284 |
| a survey of helminths of the muskrat, ondatra z. zibethica miller, 1912, in portage county, ohio. | | 1967 | 5624878 |
| temperature-related nerve function in warm- and cold-climate muskrats. | | 1967 | 6054880 |
| [some observations on behavior of the adrenergic system in the muskrat ondatra zibethica l]. | | 1967 | 4167709 |
| [studies on the distribution of rabies in muskrats (ondatra zibethica l.) in a biotope of the usedom island]. | | 1966 | 5998338 |
| the chromosomes of the muskrat. | | 2003 | 6006810 |
| [mixed zoonotic tularemia and omsk hemorrhaging fever in muskrats in western siberia]. | | 1964 | 14336021 |
| toxoplasma microti (the m-organism) in the muskrat (ondatra zibethica). | | 1963 | 17421639 |
| heat exchange through the muskrat tail. evidence for vasodilator nerves to the skin. | | 2006 | 14451948 |
| tularemia of muskrats in eastern ontario. | | 1960 | 13723090 |
| tularemia among muskrats on walpole island, lake st. clair, ontario. | | 1959 | 17649145 |
| osteogenic sarcoma in a muskrat from an area of high environmental radiostrontium. | | 1954 | 13147639 |
| an outbreak of tularaemia in beaver and muskrat in waterton lakes national park, alberta. | | 1954 | 17648685 |