Mice Peromyscus Leucopus Research Articles

Molecular Characterization of Sylvatic Isolates of Trichinella spiralis

Genetic relationships of 20 Trichinella isolates from Indiana wildlife were assessed and compared to Trichinella isolated from an infected swine herd. Trichinella larvae were isolated from coyotes, mink, raccoons, and red foxes. The larvae were maintained and amplified in white mice (ICR) and wild mice (Peromyscus leucopus). Differences in phenotypic characters of sylvatic isolates in the 2 laboratory hosts included an approximately 10-30-fold increase in parasite fecundity in wild mice. DNA for each isolate was extracted from Trichinella larvae and analyzed by dot-blot hybridization using a repetitive DNA probe pBP2 that recognizes DNA sequences specific for swine Trichinella. The probe hybridized only to Trichinella from swine and a single coyote isolate. Restriction endonucleases were used to digest DNA and the resulting fragments were separated by gel electrophoresis. Based on the presence of repetitive DNA sequences in the Trichinella genome, distinctive banding patterns were seen among the isolates. Trichinella isolated from swine had a pattern distinct from all sylvatic isolates except 1 from a coyote. Because this coyote was from the same general locality as the swine Trichinella outbreak, it was concluded that the isolate represents transmission of swine trichinellosis to the wildlife population. Further analysis using the enzyme Cla I identified unique banding patterns for wild isolates, suggesting that the sylvatic group is a genetically heterogeneous complex.

Efficacy of the urinary bladder for isolation of Borrelia burgdorferi from naturally infected, wild Peromyscus leucopus.

The efficacy of culturing urinary bladder tissue for Borrelia burgdorferi from naturally infected, wild Peromyscus leucopus mice was determined. The urinary bladder cultures were as efficient as spleen, kidney, and blood tissue cultures. The rapid B. burgdorferi isolation (mean, 6 days) from mouse urinary bladders should aid in defining new Lyme disease foci.

Learning in mature mice (Peromyscus leucopus) subjected to deep hypothermia as neonates.

In certain species of nonhibernating rodents, although young nestlings cease breathing and heart action when their body temperature is lowered to near freezing, the nestlings need only be rewarmed to recover. This remarkable capacity for immediate recovery has been known many years, but long-range consequences of deep neonatal hypothermia have never before been investigated. Mice (Peromyscus leucopus) that had been exposed to four 2.5-hr episodes of deep (2-4 degrees C) hypothermia when 4-10 days old were later compared with littermate controls in their performance on two learning tasks. The two groups did not differ in their acquisition or extinction of a lithium-induced learned taste aversion to sucrose. Nor did they differ in learning to find a hidden platform in a swimming pool. Thus in a nonhibernating rodent species, deep hypothermia experienced neonatally--unlike similar hypothermia administered in adulthood--seems not to induce deficits in subsequent learning capabilities. The resistance of neonates to damage probably represents an adaptation, for their modest thermoregulatory abilities render them vulnerable to deep hypothermia in frigid environments.

Neurons in the suprachiasmatic area are labelled after intravenous injections of horseradish peroxidase.

Intravenous injections of horseradish peroxidase (HRP) produced labelled neurons in the suprachiasmatic area of house mice (Mus musculus), deer mice (Peromyscus maniculatus bairdi), and white-footed mice (Peromyscus leucopus). In the two species of Peromyscus, a significant proportion of the labelled cells was found within the suprachiasmatic nucleus (SCN). These results suggest that when HRP is injected in the eyes to trace retinal inputs to the hypothalamus, some of the reaction product seen in the SCN may represent blood-borne transport of the enzyme.

Duration of the Melatonin Pulse in the Hypothalamus Controls Testicular Function in Pinealectomized Mice (Peromyscus Leucopus)1

Forty-four pinealectomized white-footed mice (Peromyscus leucopus) were stereotaxically implanted with a guide tube-cannula assembly in the area of the preoptic/anterior hypothalamus. Easy insertion and removal of the melatonin-loaded cannula in the basal medial hypothalamus made it possible to examine whether duration of the melatonin pulse at the putative target site controls reproduction in mice. Mice receiving melatonin every day for 10 h during either the day or night underwent gonadal regression within 7 wk, as indexed by substantial decreases in combined testicular weight and seminal vesicle weight. Sperm production in these mice was also reduced or absent. Melatonin pulses given for 5 h, or as two 5-h pulses (separated by 3 h) did not alter reproduction in that these mice resembled sham-implanted controls. These results indicate that duration of the melatonin pulse, acting in the hypothalamus, may regulate seasonal reproduction in P. leucopus.

The effects of food on midsummer demography of white-footed mice, Peromyscus leucopus

At mid-latitudes, white-footed mice (Peromyscus leucopus) breed in spring and autumn with a decrease in breeding activity in July and August. A food supplement of sunflower seeds and oats was applied to two 1-ha live-trapping grids from 1 May to 13 August 1984 to determine if a high quality food supplement would stimulate reproduction in Peromyscus leucopus during the midsummer breeding hiatus. Breeding activity on treatment and control grids was high from May through June, declined considerably from early July through August, and increased again in September and October. Food had no apparent effect on the decline in reproductive activity during midsummer. During the spring breeding season, the number of females was higher on treatment than control grids, but food had no effect on number of males, pregnancy rates, home-range size, length of residence, or body weights. The breeding activity and upper limits of population density are apparently determined by factors other than food.

Intra-familial dispersion patterns in white-footed mice, Peromyscus leucopus

Spatial relationships of white-footed mouse (Peromyscus leucopus) dams and their offspring and of littermates post-weaning were determined to evaluate if their dispersion was sufficient to prevent inbreeding. Mothers tended to leave their first nest site and establish another nest site within or near their original home range. Daughters inherited part of the maternal home range but sons dispersed. During the following breeding season, sons were not in proximity to their mothers or sisters. Daughters, however, frequently attained sexual maturity and bred within the home range of males that could have been their fathers. Differential dispersal of male and female juveniles reduces the probability of mother-son and brother-sister matings, but there is no obvious dispersal-related mechanism to prevent father-daughter matings.

Temporal patterns of brain cholinesterase activities of white-footed mice (Peromyscus leucopus) following dosing with diazinon or parathion.

Brain cholinesterase (ChE) activities were determined for white-footed mice (Peromyscus leucopus) orally dosed with either diazinon (18.8 mg/kg body weight) or parathion (10 mg/kg body weight). Following treatment with diazinon, a latent period of approximately six hr elapsed during which time ChE activity was relatively unaffected. After the latent phase, ChE activity rapidly declined to a minimum 12 hr after dosing. After 48 hr, ChE activity recovered to levels only slightly below that of the controls. The response of both male and female white-footed mouse brain ChE to dosing with parathion was similar to that exhibited by animals dosed with diazinon. ChE activities declined rapidly at 6 hr and reached a minimum 24 hr after dosing. ChE activity of treated animals was comparable to that of controls 48 hr after treatment. Brain ChE activities of treated female white-footed mice were significantly lower (P<0.05) than those of treated males.

A Comparative Study of Resource Partitioning between Ochrotomys nuttalli and Peromyscus leucopus

Resource utilization was examined in captivity for two coexisting small mammal species, the golden mouse ( Ochrotomys nuttalli ) and the white-footed mouse ( Peromyscus leucopus ). Bioenergetics, thermoregulation, and food-selection behavior were studied in terms of behavioral and physiological responses to different experimental conditions. Food consumption was measured to assess ingestion, egestion, assimilation, and respiration in laboratory-maintained mice at 10°C and 20°C. Ingestion rates increased at the lower ambient temperature in both species. Assimilated energy and, consequently, respiration were higher in Peromyscus than in Ochrotomys at both ambient temperatures. Body temperature was monitored every 12 h during a 5-day period in mice maintained at 10° and 20°C; studies were conducted both with and without nesting material. Ochrotomys consistently exhibited lower mean body temperatures than Peromyscus . Body temperatures in both species were significantly higher at the lower ambient temperature (10°C). Both species appear able to use behavioral adjustment of insulation (e.g., nest construction) to retard heat loss. Feeding preferences were analyzed by presenting individuals of each species a diversity of natural foods. Dietary diversity (H′) and evenness (e) were higher in Ochrotomys , indicating more equal apportionment among food items. Electivity values (I) indicated a preference of both species for blackberry and cherry fruits and a lack of preference for sumac. Differences in size of cheek pouches may contribute to the behavioral differences observed between species. Physiological and behavioral strategies illustrate the importance of energy requirements in determining species interactions and community structure.

Demography of the Meadow Jumping Mouse (Zapus hudsonius) in Eastern Massachusetts

The meadow jumping mouse (Zapus hudsonius) was live-trapped for 5 years in eastern Massachusetts. Densities were low throughout the study, with yearly peak numbers ranging from 3.1-7.5 per ha. Female jumping mice reached sexual maturity at a weight heavier than males. Survival rates were low, but this could be attributed largely to a high degree of transiency; once mice achieved residency, loss rates were low. Demographic attributes of this population of Zapus were compared with populations of the meadow vole (Microtus pennsylvanicus) and the white-footed mouse (Peromyscus leucopus) in eastern Massachusetts. The most important differences between Zapus, which hibernates, and the two nonhibernating species were in the life span and survival of residents and the length of the breeding season. We suggest that some demographic classifications of zapodids may have been premature. INTRODUCTION Jumping mice (genus Zapus) are distributed widely in North American grasslands, and many natural history studies have been conducted on several species (Whitaker, 1972). However, few detailed studies on demography have been reported on these hibernating mice. Brown (1970) and Cranford (1983) studied the demography of several populations of Z. princeps in Wyoming and Utah, respectively, and Nichols and Conley (1982) studied a population of Z. hudsonius in Michigan. Further data on demography from Zapus populations are needed for comparison with more widely studied nonhibernating small mammals to determine how the strategies of demography of hibernators and nonhibernators differ. We report here the results of a 51-month study on the demography of a population of Zapus hudsonius in eastern Massachusetts. We compare these results with demographic features of two nonhibernating small mammals, the meadow vole (Microtus pennsylvanicus) and the white-footed mouse (Peromyscus leucopus), inhabiting grasslands in eastern Massachusetts. We are testing the model of French et al. (1975), which suggests that Zapus will show high survival, low reproductive activity and low density compared to the two nonhibernating species. MATERIALS AND METHODS Live trapping was conducted year-round in grassy fields at the Broadmoor/Little Pond Audubon Sanctuary in South Natick, Massachusetts, from August 1978 to October 1982. Data were collected from two 0.8-ha rectangular grids (gridsJ and K) consisting of 100 trap stations each. Trap stations were spaced 7.6 m apart. Grid K was bounded on three sides by a 0.75-m high galvanized steel fence as part of an experimental study of the meadow vole Microtus pennsylvanicus. The fence did not restrict movement of Zapus because individuals trapped on Grid K were often captured outside the fence. Both fields were dominated by bluegrass (Poa pratensis) and goldenrod (Solidago spp.). Eighteen additional trap stations were located 15.2 m from grid J in deciduous woodland. One Ketch-All, multiple-capture live trap was placed at each station. Traps were baited with oats and supplied with cotton for bedding. Trapping was conducted month1 Present address: George S. Wise Faculty of Life Sciences, Department of Zoology, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel.

Effects on Wildlife of At-Planting Corn Applications of Granular Carbofuran

Application, at planting, of a granular formulation of the insecticide carbofuran to 195 ha of corn resulted in wildlife mortalities in Frederick County, Maryland, in April and May 1980. Systematic field searches within 96 hours of treatment revealed six dead songbirds (order Passeriformes), five of which contained residues of carbofuran ranging from 1.6 to 17.0 ppm (gastrointestinal tract and liver combined). An American robin (Turdus migratorius) and a mallard (Anas platyrhynchos) were observed exhibiting symptoms consistent with carbofuran poisoning. A dead white-footed mouse (Peromyscus leucopus) found 24 hours posttreatment contained 15.1 ppm carbofuran. The pesticide was detected in 10 of 12 common grackles (Quiscalus quiscula) shot at the site (gastrointestinal tract and liver: f = 0.75 ppm, SE = 0.19), suggesting extensive sublethal exposure among birds feeding in treated fields. Captive house sparrows (Passer domesticus) and red-winged blackbirds (Agelaius phoeniceus) were orally administered carbofuran granules; doses as low as one granule resulted in fatalities with both species. Given the extensive annual use of granular carbofuran (>4 x 106 ha) in the United States, numerous wildlife mortalities are likely. J. WILDL. MANAGE. 48(4):1353-1359 Toxic pesticides are applied to large areas of farmland annually. The corn crop in the United States, for example, amounts to approximately 34 million ha with 11 million ha treated with insecticides (Eichers et al. 1978). When pesticides are applied in populated areas, as occurred in Dutch elm disease treatments (Hickey and Hunt 1960) or, more recently, in pesticide treatments to turf (Stone 1979), wildlife mortalities are observed and reported. Most agricultural land in the United States, however, occurs in sparsely populated areas. With few people searching for dead wildlife in treated fields and considering the rapidity with which carcasses disappear (Rosene and Lay 1963), even if kills were common they would seldom be observed and reported. The objective of our study was to investigate the effects on wildlife of at-planting corn applications of granular carbofuran (Furadan? 10 Granul s), a widely used corn insecticide (Eichers et al. 1978). We thank S. D. Palmeteer and J. A. McCann of the Terrestrial and Aquatic B ol. Lab., U.S. Environ. Prot. Agency, Beltsville, Maryland, for laboratory space and equipment. C. E. Grue, U.S. Fish and Wildl. Serv., Patuxent Wildl. Res. Cent., generously supplied the red-winged blackbirds. We thank C. Bushong, K. R. Barbehenn, and R. R. Stevens for commenting on an earlier draft of this paper. STUDY AREA AND METHODS The study area was in northwestern Maryland (Frederick County), a rural agricultural region. Cropland at the site (405 ha) is privately owned. Corn was the only c op planted at the time of the study, but in previous years some alfalfa and soybeans were grown. Fifteen fields totaling 195 ha were selected for study. The fields J. Wildl. Manage. 48(4):1984 1353 This content downloaded from 157.55.39.223 on Wed, 24 Aug 2016 05:40:50 UTC All use subject to http://about.jstor.org/terms 1354 EFFECTS OF CARBOFURAN ON WILDLIFE * Balcomb et al. were not contiguous but were interspersed with woodlots, hedgerows, fallow fields, turf, and roads. A stream bisected the area. Fieldwork was conducted from 22 April to 16 May 1980. Pesticide Applications Furadan? 10 Granules (10% carbofuran: 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) were applied at planting at the rate of 11.2 kg of product/ ha (1.12 kg active ingredient [a.i.]/ha) to control corn rootworm. Two common methods of planting were used: (1) the soil surface was plowed and disked prior to planting (115 ha), and (2) a no-till technique was used such that planting proceeded over existing soil conditions and surface litter without plowing or disking (80 ha). A White (model 543) six-row planter was used. This apparatus simultaneously plants the corn seed and applies fertilizer and insecticide (the planter opens a narrow furrow [1.5 x 4 cm], and the seed, insecticide, and fertilizer are metered in and a presswheel closes and compacts the furrow). These methods adhere to label directions and are considered typical of most corn in-furrow treatments. The pre-emergent herbicides atrazine (2.24 kg a.i./ha) and metolachlor (2.8 kg a.i./ha) were applied to plowed fields within a few hours of planting. The postemergent herbicide paraquat (0.28 kg a.i./ ha) was similarly applied to no-till areas.

Antibodies to Rickettsia rickettsii in Peromyscus leucopus from a focus of Rocky Mountain spotted fever in Connecticut.

During 1980-1982, white-footed mice (Peromyscus leucopus) were captured in Newtown, Connecticut, an area where Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever, is thought to be enzootic. An indirect microimmunofluorescence test identified specific antibodies to this organism in 16 of 237 (7%) sera: titration end points for 14 samples were relatively high (1:128-1:2048). Antibodies were detected in mice during 1980 and 1981 with monthly prevalences varying from 8 to 22%. These results suggest that P. leucopus may be involved in the ecology of R. rickettsii and that these rodents can be included along with other mammals to monitor spotted fever rickettsial infections in nature.

Effects of Early Experience on Cue Preferences of Peromyscus leucopus

Wild-reared and first-generation laboratory-reared white-footed mice (Peromyscus leucopus noveboracensis) were studied to assess the effects of early experience on cue preferences. Mice were given a choice of two opposing test chambers differing by a single cue, or by degree of a single cue, for a variety of test situations. For the majority of tests, responses of laboratory-reared and wild-reared mice did not differ significantly. However, wild-reared mice preferred a high nocturnal illuminance of 0.020 ft-c to illuminance 0.1 of that while laboratory-reared mice showed no preference. Wildreared mice preferred a visual cue oriented horizontally to an otherwise identical vertical one at high nocturnal illuminance; laboratory-reared mice showed no preference. Laboratory-reared mice chose the odor of grass to that of leaf litter, and wild-reared mice showed no preference. Presuming similar gene pools for these two closely related groups of mice, a role for early experience in certain sensory cue preferences of P. leucopus is suggested.

Sexual Maturation of Male and Female White-Footed Mice (Peromyscus leucopus noveboracensis): Influence of Physical or Urine Contact with Adults

Young white-footed mice were reared from weaning (21–24 days of age) in contact with individual adult males or their urine, individual adult females or their urine, or water. At 40 days of age the young animals were killed and their body and reproductive organ weights (testes and seminal vesicles or uteri and ovaries) were compared. Males reared in contact with adult females or their urine had developed larger testes and seminal vesicles than those in contact with water, adult males, or male urine (generally P < 0.05). Females in contact with adult males or male urine had significantly ( P < 0.05) smaller ovaries than those in contact with water, adult female urine, or adult females. Body weights of females in contact with males or male urine also averaged significantly less than those in contact with water. Additionally, females in contact with adult males or adult male urine had significantly fewer corpora lutea than those exposed to water.

Description of Sarcocystis rauschorum sp. n. (Protozoa: Sarcocystidae) with experimental cyclic transmission between varying lemmings (Dicrostonyx richardsoni) and snowy owls (Nyctea scandiaca)

Sarcocystis rauschorum sp. n. (Protozoa: Sarcocystidae) is heteroxenous, with varying lemmings (Dicrostonyx richardsoni) as expermental intermediate hosts and snowy owls (Nyctea scandiaca) as natural and experimental definitive hosts. Free sporocysts of a Sarcocystis-like organism (11.6 × 9.2 μm with a diffuse residuum of numerous small refractile granules) from intestinal scrapings of a naturally infected snowy owl were orally administered to laboratory-reared varying lemmings. Meronts were present 7 days post inoculation (DPI) in hepatocytes. Cysts of S. rauschorum sp. n. developed in striated muscle and contained metrocytes (4.6 × 3.8 μm) 14 DPI; bradyzoites (6 × 2 μm) were present at least as early as 28 DPI. Cysts at 84 DPI were not macroscopic (greatest diameter 80.9 μm, least diameter 70.9 μm) with walls 0.35–0.70 μm thick. Laboratory-reared rats (Rattus norvegicus), house mice (Mus musculus), white-footed mice (Peromyscus leucopus), red-backed voles (Clethrionomys gapped), and brown lemmings (Lemmus sibiricus) were not suitable intermediate hosts. Carcasses of varying lemmings containing cysts (57 and 84 DPI) of S. rauschorum sp. n. were fed to three Sarcocystis-free snowy owls. The prepatent period was 7 days and the patent period 12 – 19 days. Sporogony occurred in the lamina propria throughout the length of the small intestine. Free sporocysts (10.4 × 8.2 μm with a compact residuum of numerous small refractile granules) from experimentally infected owls were infective for varying lemmings.

Effect of Microhabitat Features on Habitat Use by Peromyscus leucopus

Habitat use and selection by the white-footed mouse (Peromyscus leucopus) were examined in riparian woods and associated grassy, shrubby and limestone outcrop habitats on the Konza Prairie Research Natural Area near Manhattan, Kansas. Analysis of captures on a large, irregular grid (843 stations) demonstrated significant differential use of habitat types by P. leucopus. Selection of habitat types was related to the vertical structure of the vegetation with areas of complex vertical structure (trees with large shrubs, large shrubs without trees or trees with small shrubs) selected over those with less well-developed vertical structure (trees without shrubs, small shrubs without trees or grass). The same basic pattern persisted when microhabitat features in the immediate area of traps were examined. Use of microhabitats associated with rocks, logs, stumps and fallen trees in the riparian woods revealed greater use of areas with dense cover. The use of microhabitats associated with limestone outcrops confirmed a pattern of greater use of protected than of open areas. Patterns of habitat and microhabitat use were generally consistent with the use of habitat features to avoid predators; however, food distribution was not examined and availability of food in different sites may explain part of the use patterns. Limited observations on habitat selection by Neotomafioridana suggested that competitive interactions between P. leucopus and N. floridana were relatively unimportant in the macroand microhabitat use patterns of P. leucopus.

Melatonin: identification of sites of antigonadal action in mouse brain.

Long-term implants releasing a small quantity of melatonin (45 nanograms per day) were used to determine the brain sites of the hormone's antigonadal action in a photoperiodic species, the white-footed mouse (Peromyscus leucopus). Implants in the medial preoptic and supra- and retrochiasmatic areas elicited completed gonadal regression after 7 weeks. Implants in other brain regions had little effect on the animals' reproductive state.

Small‐Mammal Associations in Forested and Old‐field Habitats: A Quantitative Comparison

Population densities, physical condition, and several parameters (diversity, niche breadth, and ratio of dominance) of small—mammal communities were documented for two old—field and two forested sites from fall 1974 to spring 1977. White—footed mice (Peromyscus leucopus) were the most numerous species in forested habitats, and populations fluctuated asynchronously and were noncyclic. Physical condition indices were not significantly different between the two forested sites, but values were significantly higher for adults than juveniles and significantly different between different sample periods. Seasonal changes in physical condition were not correlated with population fluctuations. Meadow voles (Microtus pennsylvanicus) were the most numerous species in old—field habitats, and populations were cyclic and fluctuated synchronously with a 2—yr duration between peaks. Physical condition indices were not significantly different between different census periods, but were significantly higher for adults than juveniles. Seasonal changes in physical condition were not significantly correlated with population fluctuations. There was a negative correlation between average niche breadth and the number of species occurring in each census period for both Peromyscus— and Microtus—dominated communities, which suggested the occurrence of species packing. Niche breadth of species was positively correlated with their abundance of both forested and old—field habitats. Species diversity was negatively correlated with meadow vole density, suggesting that at high densities voles competitively excluded other species of small mammals. Species diversity of small—mammal communities in both habitats were extremely variable spatially and temporally. There were significant differences in diversity indices between sites within the same habitat but not between habitats.

Seasonal changes in enzymes of aerobic heat production in the white-footed mouse.

During seasonal acclimatization in white-footed mice (Peromyscus leucopus), there is a substantial increase in the capacity for aerobic heat production under cold stress (Mmax) in winter animals. The possibility that increases in levels of enzymes involved in aerobic heat production could be responsible for the increase in Mmax was investigated in mice captured in summer and winter. Activities of citrate synthase (CS) and beta-hydroxyacyl-CoA dehydrogenase (HOAD) and concentrations of cytochrome c (cyt c) were measured in the two primary thermogenic tissues of small mammals, skeletal muscle and brown adipose tissue (BAT). Additionally, cyt c was measured in heart, liver, and whole-body samples. CS and cyt c were used as indicators of aerobic capacity, and HOAD was used to indicate the capacity for beta-oxidation. In winter CS, cyt c, and HOAD increased (expressed per g wet mass) in skeletal muscle and BAT. There was an increase in cyt c of whole-body samples, liver, and skeletal muscle of between 55 and 78%, but no change was observed in cardiac tissue. There was an approximately 80% increase in CS and HOAD in skeletal muscle. The highly aerobic nature of BAT and its primary role in heat production are supported by the high activities in summer animals and the increase observed in winter (200, 1,570, and 220% increase in CS, HOAD, and cyt c, respectively).

High resolution two-dimensional electrophoretic mapping of immunoglobulin light chains

Staphylococcus protein A immunoadsorbents were used to purify immunoglobulins from the sera of adult inbred (BALB/c) or outbred ( Peromyscus leucopus) mice which had been raised under similar conditions. High resolution two-dimensional gel electrophoretic patterns of light-chains from individual BABL/c mice showed that 70–80% of the 1̃00 spots observed occur in patterns from all animals. The light-chain patterns from outbred P. leucopus showed only 3̃0% commonality with many more total spots. Possible implications of these results and the advantages of the 2-D technique for monitoring antibody repertoires are discussed.