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PubMed1984

Atropine esterase status of laboratory mice.

Fifty eight inbred strains of laboratory mice and two species of wild mice [Mus castaneus (inbred) and Peromyscus maniculatus bairdii (closed colony)] were tested for the presence of atropine esterase by the microhematocrit tube test of Tucker and Beattie. The results show clearly that laboratory mice do not have significant levels of atropine esterase as determined either by the microhematocrit tube test or by the agar plate test, and therefore that under these conditions atropine esterase is not a polymorphic variant as has been demonstrated clearly in the rabbit.

Animals↗
PubMed1984

Industrial lead contamination of an Illinois wildlife refuge and indigenous small mammals.

Deer mice (Peromyscus maniculatus) were trapped from a sand prairie at various distances from an adjacent battery lead reclamation plant. Analysis of liver, kidney, and bone for lead concentrations showed an increase of tissue lead concentrations over controls to a distance of approximately 400 m. Soil and plant lead concentrations roughly correlated with the findings in deer mouse tissues. At higher tissue lead concentrations, acid-fast staining intranuclear inclusions within renal tubular epithelial cells were an occasional finding.

Animals↗
PubMedDate not supplied

Avian and mammalian hosts for spirochete-infected ticks and insects in a Lyme disease focus in Connecticut.

Spirochetes and their vectors and reservoirs were studied in a Lyme disease focus in East Haddam, Connecticut, from mid-May through September 1983. Ixodes dammini subadults were comparable in number on white-footed mice (Peromyscus leucopus) (means = 2.9 +/- 3.6 SD) to those on 27 different species of birds (means = 2.3 +/- 4.2 SD) representing 11 families within the order Passeriformes. Less commonly found ticks on birds (means less than or equal to 0.1) were immature Ixodes dentatus and Haemaphysalis leporispalustris. Although spirochete-infected I. dammini larvae and nymphs were taken off eight and nine different species of birds, respectively, significantly fewer positive larvae were removed from birds than from white-footed mice. Spirochetes were detected in the midguts of I. dammini, Dermacentor variabilis, and H. leporispalustris and two species of insects (Cuterebra fontinella and Orchopeas leucopus). Possibly, arthropods other than I. dammini vector these spirochetes in northeastern United States. Spirochetes grew in a cell-free medium inoculated with bloods from four white-footed mice, one woodland jumping mouse (Napaeozapus insignis), one northern mockingbird (Mimus polyglottos), one gray catbird (Dumetella carolinensis), two prairie warblers (Dendroica discolor), one orchard oriole (Icterus spurius), one common yellowthroat (Geothlypis trichas), and one American robin (Turdus migratorius). We suggest that avian hosts, like mammals, develop spirochetemias of the causative agent of Lyme disease. Erythematous tissues from a white-footed mouse were infected with spirochetes.

Animals↗
PubMedDate not supplied

Prevalence of the Lyme disease spirochete in populations of white-tailed deer and white-footed mice.

The prevalence of the Ixodes dammini spirochete (IDS) in white-tailed deer (Odocoileus virginianus) and white-footed mice (Peromyscus leucopus) was studied on the eastern end of Long Island, New York. Both species commonly occur in a variety of habitats, are preferred hosts of Ixodes dammini, and can harbor the spirochetes in the blood. Each animal was examined for spirochetemia, tick infestation, and IDS infection rates in the ticks that were removed from it. The results obtained suggest that in winter deer can be infected by questing adult I. dammini. Adult ticks apparently are infected through transtadial transmission of spirochetes from subadult ticks which had fed earlier in their life history on infected animals. Deer are important hosts of adult ticks and the IDS in winter and probably are a reservoir host in other seasons. The patterns of spirochete prevalence suggest that deer and mice are reservoirs of the organism and thus are fundamental to the ecology of Lyme disease on Long Island.

Animals↗
PubMed1982

Evidence for turnover of DNA in the nucleus and in the cytoplasm of adult post-mitotic neurons in vivo.

Experiments were designed to determine if turnover of DNA occurs in post-mitotic neurons of adult mammals. Three-month-old laboratory mice, Mus musculus, and white footed mice, Peromyscus leucopus, were given three injections of 3H-thymidine (3H-TdR, 16 muCi/g body weight) at noon, 4 pm and 8 pm, and were killed serially beginning 1 h after the last injection. The brain stem was removed from the animals and autoradiographed. Some of the sections were treated with DNase prior to autoradiography. A sensitive and accurate method of autoradiographic grain count analysis was used to measure the grain counts over areas of neuron nuclei, neuron cytoplasm and background areas of the slide (Cameron, Pool and Hoage, 1979). There was a significant elevation of grains per unit area above background over both the nucleus and the cytoplasm in animals killed 24 h after the last 3H-TdR injection. Counts were reduced to background level by prior DNase treatment. This shows that the grains over the nucleus and the cytoplasm were due to label in the DNA. Changes in the grain counts with time were subjected to least squares regression analysis. In the mouse both the nucleus and the cytoplasmic grain counts showed a decreasing slope which was significantly different from a slope of zero when the data were fitted to either a linear model or a log-linear model. The data showed a somewhat better fit to the log-linear model. The labelled nuclear DNA in the mouse had a calculated half-life of about 502 h while the labelled cytoplasmic DNA had a calculated half-life of about 97 h. Our ability to measure and to characterize DNA turnover in specific in vivo cell types allows us to test theories about its functional role.

Animals↗
PubMed1980

Methods for detecting Babesia microti infection in wild rodents.

We compared various methods for detecting Babesia microti infection in white-footed mice (Peromyscus leucopus) captured in enzootic regions of Massachusetts. The most sensitive method tested involved inoculating blood from wild rodents into hamsters. One month postinoculation proved to be the optimal time for microscopically examining blood of inoculated hamsters. With this method, as few as 300 organisms produced patent infection. Prior splenectomy of hamsters did not increase susceptibility to infection. For direct study of captured animals, a Giemsa-stained, thin blood-film prepared from the animal's tail was the most convenient method tested. However, this method detected only 61% of infections identified by hamster inoculation.

Animals↗
PubMed1980

Ultrastructure and acid phosphatase activity in hereditary cataracts of deer mice.

Lenses of cataract-webbed (cw) Peromyscus maniculatus were examined by electron microscopy and compared to age-matched normal deer mouse lenses. Precataractous lenses of offspring of cw/cw matings were examined and compared to early cataract development in the opposite eye of the same animal. The earliest ultrastructural change leading to disturbance of lens transparency was cell fusion and formation of fiber cell syncytia in the posterior subcapsular region. Fiber cells lost their regular hexagonal packing. Small osmiophilic densities on the plasma membrane coincided with many of the sites of cell confluency. Larger osmiophilic whorls were usually localized in ball-and-socket interlocking junctions after the opacity spread. Epithelial cells from the nasal ventral equator migrated to the posterior pole. Later when underlying cortical fibers ruptured, the migrated cells phagocytized lens proteins and incorporated them in acid-phosphatase positive lysosomes. Fiber cells 3 to 20 layers deep in the cortex of normal and cataractous lenses had acid phosphatase reaction product coating the plasma membrane; the possible significance of this finding is discussed. We postulate that this hereditary cataract results from a defect in turnover and control of plasma membrane components.

Acid Phosphatase↗
PubMed1995

Fleas (Siphonaptera) of cotton mice on a Georgia barrier island: a depauperate fauna.

From February 1993 through October 1994, 382 cotton mice Peromyscus gossypinus were live-trapped and examined for fleas on St. Catherines Island, Liberty County, Georgia. Orchopeas leucopus was the only species of flea collected, with an overall prevalence of 27% and a mean intensity of 3.8. This flea was more abundant on cotton mice during the cooler months, with peak infestation indices recorded in March 1993 and in January 1994. Five species of fleas (Polygenis gwyni, Stenoponia americana, Ctenophthalmus pseudagyrtes, Peromyscopsylla scotti, and O. leucopus) were collected from 29 cotton mice live-trapped in adjacent mainland localities during the same period. The depauperate flea fauna of cotton mice on St. Catherines Island suggests that either the original colonizing cotton mice were infested by only 1 species of flea (O. leucopus) and that no subsequent invasions of cotton mouse fleas have occurred, or that other cotton mouse fleas cannot establish on the island.

Animals↗
PubMed1994

Influence of season and habitat on Ixodes scapularis infestation on white-footed mice in northwestern Illinois.

The effects of season and habitat on the infestation of the white-footed mouse (Peromyscus leucopus) by immature Ixodes scapularis were studied at Castle Rock State Park, northwestern Illinois, during June-October 1991. Relative density of larvae on mice was higher in mid-late summer (13.7 ticks per mouse) than during the rest of the study period, whereas prevalence of nymphal infestation was highest in early summer (33.3%). Relative density of I. scapularis larvae and prevalence of nymphs on mice did not differ significantly among bottomland forest, field-forest ecotone, and upland forest habitats. In bottomland forest, total number of ticks collected from mice (472 larvae and 13 nymphs) and P. leucopus population density (6.6 mice per 0.36 ha) were higher than in the other habitats. Temporal patterns of numbers of larvae collected from mice and through dragging in bottomland forest were significantly correlated.

Animals↗
PubMed1994

Etiology and epidemiology of the Four Corners hantavirus outbreak.

In May and June 1993, a handful of previously healthy residents of rural areas in the Four Corners region of the southwestern United States died of acute unexplained respiratory distress, later diagnosed as hantavirus pulmonary syndrome. Their illnesses were characterized most prominently by a prodrome of fever and myalgias, followed by thrombocytopenia, the presence of immature white blood cells on the peripheral smear, and catastrophic respiratory decline associated with the sudden onset of noncardiogenic pulmonary edema and hypotensive shock. Although the primary care doctors who treated these patients were spread over a relatively wide rural geographic area, this cluster was recognized in large part because these patients belonged to a defined cohort receiving medical care from a unified system of interconsulting physicians, the Indian Health Service. By just over 2 weeks after receiving laboratory diagnostic specimens, Public Health Service scientists had identified a newly recognized hantavirus as the cause of this disease cluster and Peromyscus maniculatus (the deer mouse) as the rodent reservoir for this zoonotic virus. The oral history of local American Indian healers describes clusters of similar deaths occurring over three cycles during the twentieth century in association with identifiable ecological markers. The abrupt introduction to Western medical practitioners of a disease long recognized by indigenous healers through illness occurring among a cohort of patients seeking care from medical officers of the U.S. Uniformed Services parallels the initial Western medical recognition of previous human illnesses associated with hantaviral infections through disease outbreaks among military troops. The remarkable speed with which the etiology of this disease was elucidated is attributable to both the power of modern genetic investigational techniques and the scientific groundwork laid by nearly half a century of systematic research on hantaviruses.

Animals↗
PubMed1994

Genetic, phenotypic, and behavioral variation in North American sylvatic isolates of Trichinella.

Two restriction endonucleases (Cla I and Hpa II) produced polymorphic repetitive DNA profiles which were used in a clustering analysis to quantify the level of genetic variation among 14 North American sylvatic isolates of T5 Trichinella. Differences in genetic profiles reflected phenotypic differences in parasite reproductive success as measured by an isolate's reproductive capacity index in natural hosts. Two genetically distinct isolates of the T5 genotype and T. spiralis were used to infect white-footed mice Peromyscus leucopus for a behavioral analysis. Three behavioral characteristics were tabulated from videotapes: time to emerge from cage, time spent inside cage, and number of rears (index of exploratory activity). Mice infected with 400 T. spiralis larvae showed a significant decrease in exploratory activity and significant increases in time to emerge and time spent inside cage, whereas mice infected with 200 larvae displayed no differences in behavior. Mice infected with a T5 isolate from a raccoon (R9) also displayed decreased exploratory activity. In contrast, mice infected with the other T5 isolate from a coyote (C26) showed relatively constant rearing levels but spent less time inside their cages during the late period of the infection. Results suggest that different genetic strains of Trichinella induce varied types of behavioral modifications upon their hosts.

Animals↗
PubMed1994

Parasitic arthropods of white-footed mice at McClintic Wildlife Station, West Virginia.

Seven species of parasitic arthropods (one sucking louse, one bot, 2 fleas, one tick, and 2 mites) were recovered from 81 white-footed mice, Peromyscus leucopus, live-trapped on the grounds of the McClintic Wildlife Station, Mason County, WV, from March through November 1990. The most commonly collected arthropods were the fleas Orchopeas leucopus (89 specimens) and Epitedia wenmanni (23), and the tick Dermacentor variabilis (38). Sex ratios for both flea species were female biased; 1.8:1.0 for O. leucopus and 1.6:1.0 for E. wenmanni.

Animals↗
PubMed1993

Molecular basis of the alcohol dehydrogenase-negative deer mouse. Evidence for deletion of the gene for class I enzyme and identification of a possible new enzyme class.

The molecular basis of the alcohol dehydrogenase (ADH)-negative deer mouse (Peromyscus maniculatus) has been investigated. Several classes of mammalian ADHs have been recognized based upon biochemical and structural properties. ADH cDNA clones identified by hybridization to a mouse class I ADH cDNA clone were obtained from a deer mouse ADH-positive liver cDNA library. This cDNA has been identified as being a class I sequence and represents the deer mouse Adh-1 gene. An additional cDNA sequence identified in both the ADH-positive and -negative deer mouse cDNA libraries was identified by weak cross-hybridization to the mouse cDNA. This cDNA encodes an amino acid sequence representing a new class of mammalian ADH, and the deer mouse gene for this ADH is named Adh-2. ADH-negative deer mice do not produce mRNA, that is detected by the Adh-1 cDNA probe. However, both stocks of deer mice produce high levels of Adh-2 mRNA in liver. Southern analysis using an essentially full-length Adh-1 cDNA probe has shown that the Adh-1 gene is deleted in the ADH-negative mice. Biochemical analysis of enzyme activity suggests at least three ADH polypeptides are expressed in different tissues and have somewhat different substrate specificities, as in the mouse.

Alcohol Dehydrogenase↗
PubMed1993

Parasitic arthropods of sympatric opossums, cotton rats, and cotton mice from Merritt Island, Florida.

Six species of parasitic arthropods were collected from 12 opossums (Didelphis virginiana), 8 species were obtained from 28 cotton rats (Sigmodon hispidus), and 4 species were collected from 10 cotton mice (Peromyscus gossypinus) from Merritt Island, Brevard County, Florida. The flea Polygenis gwyni was the only parasite that infested all 3 host species, and it was present in very high densities (mean intensity = 73.7) on the opossums. The American dog tick, Dermacentor variabilis, and the tropical rat mite, Ornithonyssus bacoti, both infested 2 host species but were principally associated with opossums and cotton rats, respectively. All remaining arthropod species were confined to single host species, suggesting host specificity by these parasites. The atopomelid mite Didelphilichus serrifer and the myobiid mite Radfordia sigmodontis constitute new state records for Florida. The reptile tick Amblyomma dissimile is recorded from a cotton mouse for the first time; Merritt Island may represent the most northerly location for viable populations of this tick in the U.S.A.

Animals↗
PubMed1997

Trichinella spiralis (T1) and Trichinella T5: a comparison using animal infectivity and molecular biology techniques.

We compared Trichinella T5 of bobcat (Lynx rufus) origin with Trichinella spiralis (T1) by using animal infectivity and molecular biology techniques. Swine, SD rats, and CF1 mice were highly resistant to infection with Trichinella T5 but sensitive to T. spiralis, whereas deer mice (peromyscus maniculatus) had similar sensitivity to both parasites. The fecundity of Trichinella T5 in deer mice was 10-35-fold higher in comparison to the fecundity in laboratory rodents (SD rats and CF1 mice). Fecundity of T. spiralis was approximately the same in both groups. A western blot, using excretory-secretory proteins (ESP) from first-stage larvae of T. spiralis as antigen, showed similar banding patterns in the pigs infected with either T. spiralis or Trichinella T5, however, the homologous reaction was stronger than the heterologous reaction. Antibodies were detectable in swine sera commencing 3 or 5 wk postinfection with T. spiralis or Trichinella T5, respectively. Complementary DNAs encoding the 46-, 49/43-, or 53-kDa ESP showed 3.54, 1.94, and 5.91% differences, respectively, between the 2 parasites. Deduced amino acid sequences of the 3 cDNAs were different at 7.20, 5.08, and 8.55%, respectively. All recombinant proteins of the 3 cDNAs from both parasites could detect antibodies in positive sera. The sequences of cDNAs encoding the 46-, 49/43-, or 53-kDa ESP from T. spiralis are also compared to the previously reported sequences, and the differences are discussed.

Amino Acid Sequence↗
PubMed1997

Hantavirus pulmonary syndrome.

The objective of this report is to summarize the medical literature relevant to the epidemiology, diagnosis, treatment, and control of hantavirus pulmonary syndrome (HPS). The English language literature was searched from January 1993 through March 1995, manually and using Medline, including conference proceedings and reference lists. We selected relevant articles on clinical aspects of HPS. HPS is a newly described illness that progresses through three phases: prodromal, cardiopulmonary, and convalescent. Its hallmark is the rapid progression from nonspecific prodromal symptoms to respiratory insufficiency caused by noncardiogenic pulmonary edema. Unlike other hantavirus infections, renal involvement and hemorrhagic manifestations are not dominant features in HPS. Treatment is based on close intensive care monitoring, oxygen, and cardiovascular support with inotropic and vasopressor drugs. Preventive measures include avoiding contact with rodents and their excrement. Peromyscus maniculatus is the primary rodent vector for the Sin Nombre virus, which caused the epidemic of HPS in the southwest United States in May 1993. HPS has a unique set of clinical findings and is caused by a genetically distinct hantavirus. Physicians and other health professionals should consider this disease when evaluating patients with unexplained respiratory insufficiency after a febrile prodrome, especially when history suggests possible rodent contact. Sporadic cases and possibly epidemics of HPS are likely in the future, particularly when ecological changes increase the population of infected rodent vectors in an area.

Animals↗
PubMed1998

Density-dependent factors regulating feeding success of Ixodes scapularis larvae (Acari: Ixodidae).

We studied the effects of different parasite and host densities on the feeding success of larval Ixodes scapularis ticks upon white-footed mice Peromyscus leucopus. Mice were infested daily with 10, 25, 50, or 100 larvae and kept individually or in groups of 2 and 3 to simulate co-nesting in the field. Engorgement weight and molting success of replete larvae did not change during more than 3 wk of continuous infestation, but overall larval feeding success decreased from 24% to 12% with increased infestation density. Grooming was observed in response to unattached, crawling larvae, and grooming of unfed ticks increased with infestation density. Nearly all larvae completed engorgement once attached, although a few were groomed accidentally along with unattached ticks. Co-nesting mice fed 2-3 times fewer ticks than did solitary mice because of increased frequency of self-grooming in the presence of nest-mates, but differences between groups of 2 or 3 mice were not significant. Thus, increased mouse density may reduce the density of the tick population at first, but further increase in the number of co-nesting mice does not affect the feeding success of larval I. scapularis and increased mouse density will increase tick density.

Anesthesia↗
PubMed1998

Host preferences and temporal trends of the tick Ixodes angustus in north-central Alberta.

We examined host preferences and temporal trends of the tick Ixodes angustus on small mammals in north-central Alberta. Small mammals were live-trapped from 1 June to 29 September 1994 and 3 May to 30 June 1995 in mature aspen (Populus tremuloides) forest near Lac La Biche, Alberta. Abundance of female I. angustus was high in early May (0.90 +/- 0.20 [SE]) and peaked again in late June (0.58 +/- 0.16), whereas abundance of immature I. angustus peaked (1.2 +/- 0.35) in mid-July. Red-backed voles (Clethrionomys gapperi) and deer mice (Peromyscus maniculatus) were the most common host species encountered, and tick abundance (number of ticks per animal examined) on these hosts was strongly influenced by species and sex. Clethrionomys gapperi had higher tick abundance (0.73 +/- 0.07) than did P. maniculatus (0.04 +/- 0.01), and ticks were more abundant on large male C. gapperi (0.97 +/- 0.14) than they were on large female C. gapperi (0.36 +/- 0.08; P = 0.0007). Characteristics of each species and sex of host in relation to susceptibility to parasitism are discussed.

Alberta↗