Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| evolution of transthyretin gene expression in the liver of didelphis virginiana and other american marsupials. | the occurrence of the thyroid hormone-binding plasma protein transthyretin in the bloodstream was investigated for four american marsupial species. serum samples were analyzed by incubation with radioactive t4, followed by electrophoresis, then autoradiography, and western blotting. transthyretin was found in serum from monodelphis domestica, didelphis virginiana, caluromys lanatus, and dromiciops australis. for unambiguous identification, transthyretin from d, virginiana was purified from serum ... | 1996 | 8754780 |
| methylation analysis of a marsupial x-linked cpg island by bisulfite genomic sequencing. | paternal x chromosome inactivation occurs in rodent extraembryonic membranes and in all tissues of marsupials. methylation of cpg islands occurs on the inactive x in eutherians and is considered to be a stabilizing mechanism. the only previous study of a marsupial x-linked cpg island was of the g6pd gene of the virginia opossum, in which the paternally derived allele is not completely repressed. we have cloned the 5' end of the g6pd gene from an australian marsupial, the common wallaroo, and seq ... | 1996 | 8919690 |
| perivitelline space of marsupial oocytes: extracellular matrix of the unfertilized oocyte and formation of a cortical granule envelope following the cortical reaction. | the purpose of this study was to characterize the structure of the vestments surrounding unfertilized and cortical granule-reacted oocytes from a marsupial, the grey short-tailed opossum monodelphis domestica and to determine if a cortical granule envelope (cge) forms in the perivitelline space (pvs) following the cortical reaction. unfertilized oocytes collected from mature ovarian follicles and oviducal oocytes that had undergone a cortical reaction were fixed for electron microscopy in the pr ... | 1995 | 8588937 |
| man and the chimaera. selective versus neutral oxytocin evolution. | the oxytocin/vasopressin superfamily encompasses vertebrate and invertebrate peptides and therefore the ancestral gene encoding the precursor protein antedates the divergence between the two groups, about 700 million years ago. the preserved nonapeptide pattern indicates that both the precursor structures and the processing enzymatic machinery were greatly conserved to ensure the building of a specific conformation. substitutions, which may be neutral or selective, occurred in precise positions. ... | 1995 | 8714026 |
| identification of opossums (didelphis virginiana) as the putative definitive host of sarcocystis neurona. | sarcocystis neurona is an apicomplexan that causes equine protozoal myeloencephalitis (epm) in north and south america. horses appear to be an aberrant host, because the merozoites continually divide in the central nervous system, without encysting. the natural host species has not previously been identified. the small subunit ribosomal rna (ssurna) gene of s. neurona was compared to those of sarcocystis muris, sarcocystis cruzi, toxoplasma gondii, and cryptosporidium parvum to identify a unique ... | 1995 | 8544064 |
| sarcocystis falcatula from passerine and psittacine birds: synonymy with sarcocystis neurona, agent of equine protozoal myeloencephalitis. | equine protozoal myeloencephalitis (epm) is a neurologic disease of horses caused by sarcocystis neurona. the horse is a dead-end host for s. neurona and the definitive and intermediate hosts have not previously been identified. we hypothesized that s. neurona is actually sarcocystis falcatula, a parasite that cycles in nature between virginia opossums (didelphis virginiana) and any of a variety of avian intermediate hosts. we extracted dna from s. falcatula sarcocysts in the muscle of a brown-h ... | 1995 | 8544067 |
| effect of deer exclusion on the abundance of immature ixodes scapularis (acari: ixodidae) parasitizing small and medium-sized mammals. | effects of deer exclusion on abundance of immature ixodes scapularis say parasitizing small and medium-sized mammals, and the role mammals have in introducing ticks to exclosure areas, were examined at two sites in westchester county, new york. in total, 686 mammal captures representing nine species were obtained, with white-footed mice, peromyscus leucopus rafinesque, composing > 80% of all captures, followed by raccoons, procyon lotor (l.); opossums, didelphis virginiana (kerr); and striped sk ... | 1995 | 7869342 |
| the distribution of gap-43 immunoreactivity in the central nervous system of adult opossums (didelphis virginiana) with notes on their development. | the distribution of the growth associated protein gap-43 has been described in the brain and spinal cord of rats and other placental mammals but not marsupials. in order to provide such information, we employed a monoclonal antibody to immunostain for gap-43 in the central nervous system of adult and developing opossums, didelphis virginiana. the gap-43 immunoreactivity was widely distributed in the brain of adult opossums, but it was particularly dense within specific layers of the olfactory bu ... | 1995 | 7749727 |
| nucleotide sequence of a marsupial line-1 element and the evolution of placental mammals. | l1 (line-1) elements, previously described in several placental species, were shown to exist in several thousands of copies dispersed in the genome of a marsupial (the north american opossum, didelphis virginiana). a restriction fragment containing the partial nucleotide sequence of the reverse transcriptase gene (orf-2) from the marsupial l1 element was cloned and sequenced. the element was shown to evolve in concert within the marsupial when compared to placental mammals. when the marsupial l1 ... | 1995 | 7476141 |
| insulin-like growth factor improves renal architecture of fetal kidneys with complete ureteral obstruction. | others have previously demonstrated that the administration of insulin-like growth factor-i accelerates recovery from ischemic acute tubular necrosis in the rat kidney. we investigated the effect of insulin-like growth factor-i on the histology of unilaterally obstructed kidneys in the pouch young of the north american opossum, didelphis virginiana. in this model complete unilateral ureteral obstruction reliably induces statistically significant degrees of caliceal dilatation, tubular cystic cha ... | 1995 | 7609156 |
| distribution of corticotropin-releasing factor (crf) binding sites in the opossum cerebellum. | corticotropin-releasing factor (crf) has been demonstrated in the hypothalamic-pituitary-adrenal axis and studied in extrahypothalamic sites throughout the brain. localization of crf immunoreactivity, crf mrna, and crf receptors within specific brain areas supports an extrahypothalamic function for crf. previous reports have revealed the localization of several peptides, including crf, in the cerebellar cortex and nuclei of the north american opossum (didelphis marsupialis virginiana); climbing ... | 1995 | 7746352 |
| developmental progression of gpd expression from the inactive x chromosome of the virginia opossum. | metatherian (marsupial) mammals possess a non-random form of x-chromosome inactivation in which the paternally-derived x is always the one inactivated. to examine the progression of x-linked gene expression during metatherian development, we compared relative levels of the maternally and paternally encoded gpd gene products in heterozygous female virginia opossums (didelphis virginiana) across a major portion of the developmental period. panels of tissues obtained from fetuses, newborns, and pou ... | 1995 | 7641417 |
| effects on breathing of medullary bicuculline microinjections in immature opossums. | the role of medullary gamma-aminobutyric acid a (gabaa)-receptor activation in the expression of breathing was studied in suckling opossums (didelphis virginiana) from 4 to 8 wk of age. animals were anesthetized with a thiobarbiturate, and the ventral medulla was exposed so that drugs could be microinjected into the medulla with a two-barrel glass micropipette. the gabaa antagonist bicuculline at approximately 1-3 pmol total dose was injected in volumes < 1 nl; injections of saline with pontamin ... | 1995 | 8594928 |
| adenosine deaminase isoenzymes of the opossum didelphis virginiana: initial chromatographic and kinetic studies. | extracts of liver and spleen were used to isolate opossum adenosine deaminase isoenzymes (ada1 and ada2) and to determine their activities with adenosine and 2'-deoxyadenosine as substrates. km values (microm) for adenosine and 2'-deoxyadenosine, respectively, as substrates for partially purified opossum liver adenosine deaminase isoenzymes were ada1: 57 +/- 7 vs. 26 +/- 4 and ada2: 285 +/- 25 vs. 580 +/- 92. in crude spleen extract, ada2 activity was stable at 56 degrees c during 40 min of incu ... | 1995 | 7599990 |
| molecular anatomy of an endodermal gland: investigations on mucus glycoproteins and cell turnover in brunner's glands of didelphis virginiana using lectins and pcna immunoreactivity. | brunner's glands are located in the submucosa of the proximal duodenum and are unique to mammalian species. the north american opossum (didelphis virginiana) is generally regarded as a prototype marsupial that closely resembles fossil didelphids which can be placed at the beginning of mammalian evolution. the current investigation provided an opportunity for the analysis of secretory products from these glands in a species thought to be more closely related to earlier evolutionary forms. extract ... | 1995 | 7642723 |
| cytoarchitecture of the substantia nigra pars lateralis in the opossum (didelphis virginiana): a correlated light and electron microscopic study. | the substantia nigra has been divided into three subdivisions. however, the cytoarchitecture of one of these subdivisions, the pars lateralis (snl), has not been previously examined in detail at the light and electron microscopic levels in any species. in the adult opossum, the three nigral subdivisions can be easily distinguished as distinct, rostrocaudally oriented cell groups separated by neuron-free zones. thus it was possible to determine the boundaries of the snl unambiguously. this report ... | 1995 | 7604970 |
| brain growth and neocortical development in the opossum. | general brain growth and differentiation of the neocortex have been studied in the marsupial, didelphis virginiana from the 10.5 day embryo through adulthood. didelphis is born after a short gestation period of about 12.5 days, at a time when the telencephalic wall consists only of two layers and is considered to be at an embryonic stage of development. the cortical plate does not appear until late in the first postnatal week, thus neocortical development is totally a postnatal phenomenon in did ... | 1994 | 7978336 |
| hearing in primitive mammals: monodelphis domestica and marmosa elegans. | although opossums of the family didelphidae usually serve as a parsimonious starting point for tracing the otological and neurological evolution of modern mammals, audiological data for didelphid opossums is available only for the north american opossum (didelphis virginiana) which because of its large size, may be one of the least representative genera of the family. the present report extends the audiological data to two other species of didelphid opossums, monodelphis domestica, and marmosa e ... | 1994 | 7928716 |
| colocalization of nadph-diaphorase activity and certain neuropeptides in the esophagus of opossum (didelphis virginiana). | nitric oxide and various neuropeptides in the myenteric plexus regulate esophageal motility. we sought colocalization of nitric oxide synthase and neuropeptides in frozen sections of mid-portion of smooth-muscled opossum esophagus using nadph-diaphorase activity to mark the synthase and immunoreactivity to detect peptides. the peptides, all with demonstrated physiological activity in this organ, were calcitonin gene-related peptide, galanin, neuropeptide y, substance p, and vasoactive intestinal ... | 1994 | 7531620 |
| developmental plasticity of reticulospinal and vestibulospinal axons in the north american opossum, didelphis virginiana. | we have shown previously that rubral axons grow around a lesion of their spinal pathway in the north american opossum if it is made at early stages of development. in the present experiments, we have asked whether reticular and vestibular axons have the same ability. the spinal cord was hemisected at postnatal day 20, 12, or 5, well within the critical period for rubrospinal plasticity, and, approximately 30 days later, bilateral injections of fast blue were made about four segments caudal to th ... | 1994 | 7860784 |
| heavy metals in the hair of opossum from palo verde, costa rica. | levels of lead, cadmium, mercury, chromium, and manganese were measured in the hair of opossum (didelphis virginiana) from palo verde, guanacaste, costa rica. this area has some agriculture, but is slated for extensive water development that will increase ecosystem exposure to a variety of agricultural chemicals. metal levels were generally not intercorrelated except for chromium and lead, chromium and cadmium, and cadmium and lead. there were significant gender differences only for lead and chr ... | 1994 | 7811107 |
| timetable of in vivo embryonic development in the grey short-tailed opossum (monodelphis domestica). | the timing of development was examined in 496 embryos from female monodelphis domestica collected at known time intervals after video recorded mating. ovulation occurred approximately 20 hr (day 1) after mating, and fertilization was observed by 24 hr. transport through the oviducts was rapid, and pronuclear stage embryos were recovered from the uterus as early as 24 hr after mating. second cleavage had occurred by 55 hr after mating. three-celled embryos were among those collected on day 3 afte ... | 1994 | 7893485 |
| x-chromosome replication patterns in adult, newborn and prenatal opossums. | somatic cells from the opossums monodelphis domestica and didelphis virginiana were labelled with 5-bromodeoxyuridine (brdu), treated with colchicine, stained with acridine orange and examined using fluorescence microscopy. brdu-incorporated metaphase spreads from females of m. domestica at developmental stages from late bilaminar blastocysts to adults showed replication asynchrony of the two (acrocentric) x chromosomes. the long arm of one x chromosome was the latest replicating region in the e ... | 1994 | 7878226 |
| early development of cerebellar afferent systems that contain corticotropin-releasing factor. | corticotropin-releasing factor (crf) and crf binding sites have been described in the cerebellum of several species, including the north american opossum (didelphis marsupialis virginiana), the species used in the present study. inotophoretic application of this peptide in the adult cerebellum enhances the spontaneous and amino acid-induced firing rate of purkinje cells and overcomes the gaba-induced suppression of purkinje cell activity. the present account provides immunohistochemical evidence ... | 1994 | 7890829 |
| distribution of cholecystokinin binding sites in the north american opossum cerebellum. | previous studies in our laboratory have reported on the differential distribution of several neuropeptides, including the octapeptide cholecystokinin (cck8), in the cerebellar cortex and nuclei of the north american opossum (didelphis marsupialis virginiana). the present account reports on the distribution of cck8 binding sites as determined from serial autoradiographic images of the cerebellum which were labelled by using [125i]bolton hunter sulfated cck8. evidence for the limited presence of c ... | 1994 | 7802965 |
| distribution of heat-stable enterotoxin/guanylin receptors in the intestinal tract of man and other mammals. | the human intestinal tract, as well as that of several eutherian and metatherian mammals, was examined for the distribution of heat-stable enterotoxin (st)/guanylin receptors. these receptors were confined to the intestinal epithelium lining the lumen and forming the intestinal glands throughout the length of both the small intestine and colon of all species examined. in man and most other mammalian species, there appeared to be a decrease in receptor density distally along the longitudinal axis ... | 1994 | 8014132 |
| the marsupial mitochondrial genome and the evolution of placental mammals. | the entire nucleotide sequence of the mitochondrial genome of the american opossum, didelphis virginiana, was determined. two major features distinguish this genome from those of other mammals. first, five trna genes around the origin of light strand replication are rearranged. second, the anticodon of trna(asp) is posttranscriptionally changed by an rna editing process such that its coding capacity is altered. when the complete protein-coding region of the mitochondrial genome is used as an out ... | 1994 | 8056314 |
| projection of visuotopically organized afferents to the dorsal thalamus in the opossum, monodelphis domestica. | retrogradely transported dyes, fluorogold and fast blue were injected into both sides of the dorsal thalamus in the monodelphis opossum. projection of the presumed primary visual cortical area, superior colliculus and parabigeminal nucleus to the dorsal lateral geniculate nucleus and the lateral posterior--lateral intermedius nuclear complex were described. they show close similarities to the homologous projections in the north american opossum, insectivores and some rodents. in comparison with ... | 1994 | 7887182 |
| experimental ureteral obstruction in the fetal opossum: histologic assessment. | in the north american opossum, didelphis virginiana unilateral complete ureteral obstruction (eco) and partial unilateral (epo) ureteral obstruction were created during the early metanephric stage of kidney development in pups attached to the teat (approximately 4.5 cm. long, 20 days old). at 70 days of pouch life (full-term equivalent in the human) some completely obstructed ureters were unobstructed with reanastomosis in the bladder (reco). other pups underwent unilateral complete ureteral lig ... | 1994 | 7966702 |
| ectoparasites of opossums and raccoons in southeastern georgia. | twelve species of ectoparasites (four fleas, three ticks, three chiggers, one macronyssid mite, and one atopomelid mite) were recovered from 42 opossums, didelphis virginiana kerr, live-trapped from september 1992 through april 1994 in southeastern georgia. the fleas, ctenocephalides felis (bouché) (prevalence = 19%) and polygenis gwyni (c. fox) (36%); the ticks, dermacentor variabilis (say) (40%) and ixodes scapularis say (19%); and the macronyssid mite, ornithonyssus wernecki (fonseca) (21%), ... | 1994 | 7815408 |
| murine typhus: updated roles of multiple urban components and a second typhuslike rickettsia. | studies using serologic and polymerase chain reaction-(pcr) facilitated analysis of field samples from southern texas indicate the presence of rickettsia typhi and elb agent infected cat fleas, ctenocephalides felis (bouché), and the first observation of elb infected vertebrates (opossums). the elb agent is a recently described typhus-like rickettsia that is not distinguished from r. typhi or r. prowazekii by currently available serologic reagents. restriction digests of pcr products from 399 fl ... | 1994 | 7966170 |
| locomotory energetics and metabolic fuel reserves of the virginia opossum. | marsupials have lower resting metabolic rates than placental mammals, but it is not clear whether particular species can extend this energetic advantage to locomotion. some active marsupials have a low cost of locomotion, but other more sedentary species, such as the virginia opossum, appear to run very inefficiently. steady-state rates of o2 consumption (vo2) and co2 production (vco2) were measured at rest and during horizontal treadmill exercise in wild-caught, trained opossums. average daily ... | 1994 | 7852899 |
| development of early cell lineages in marsupial embryos: an overview. | all major embryonic and extra-embryonic cell lineages are established before implantation in marsupials. in reptiles, birds, monotremes and most marsupials, the zygote is polarized, sometimes markedly so, and the cleavage pattern in relation to the polarized state provides the mechanism for the generation of positional signals. these ensure that the embryonic cell lineages develop in the centre of the developing blastoderm or blastocyst epithelium and the extra-embryonic lineages at the peripher ... | 1994 | 7878224 |
| ixodes dammini (acari: ixodidae) infestation on medium-sized mammals and blue jays in northwestern illinois. | high prevalence of infestation of five species of medium-sized mammals and blue jays, cyanocitta cristata (l.), by immature ixodes dammini spielman, clifford, piesman and corwin was found in castle rock state park in northwestern illinois during may-august 1991. raccoons, procyon lotor l., and opossums, didelphis virginiana kerr, were infested with the highest larval densities and were trapped primarily in bottomland forest and ecotone habitats. all species had similar nymphal densities, except ... | 1993 | 8254647 |
| 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 tropi ... | 1993 | 8459341 |
| opossum serum alpha 1-proteinase inhibitor: purification, linear sequence, and resistance to inactivation by rattlesnake venom metalloproteinases. | opossum (didelphis virginiana) serum was fractionated with (nh4)2so4 and then chromatographed on deae-sepharose and phenyl-sepharose. affinity chromatography on a protein a-sepharose-antibody column removed traces of opossum serum metalloproteinase inhibitors, and resulted in a homogeneous preparation of opossum alpha 1-proteinase inhibitor (alpha 1-pi). the inhibitor is a single-chain glycoprotein (17.7% carbohydrate) with an estimated m(r) = 54,000. an opossum liver cdna library was immunoscre ... | 1993 | 8422360 |
| oxidation reactions of human, opossum (didelphis virginiana) and spot (leiostomus xanthurus) hemoglobins: a search for a correlation with some structural-functional properties. | 1. relative to human hba, opossum (didelphis virginiana) hemoglobin was found to be more susceptible to autoxidation. while the initial rate of autoxidation of spot (leiostomus xanthurus) hemoglobin is close to that of hba, complete oxidation occurs in 50 hr. 2. direct addition of hydrogen peroxide (h2o2) induced oxidation of hemoglobins in a definite order: spot hb > hba > opossum hb. excess h2o2 led to heme degradation and precipitation that occurred much faster for spot hb than the case with ... | 1993 | 8243064 |
| the effect of enzyme replacement on red cell adenine deoxyribonucleotides in adenosine deaminase-deficient erythrocytes of the opossum, didelphis virginiana. | 1. polyethyleneglycol-modified bovine adenosine deaminase was administered (10-20 u/kg/week) intramuscularly to two opossums for 15 weeks and changes in red cell adenine ribo- and deoxyribonucleotides quantitated by hplc. 2. only a moderate decline of erythrocyte daxp was observed at the end of the study when compared to results of enzyme replacement seen in human adenosine deaminase deficient patients. 3. opossum red cells salvage substantial amounts of deoxyadenosine provided in physiologic (5 ... | 1993 | 8281757 |
| 2'-deoxyadenosine metabolism in human and opossum didelphis virginiana erythrocytes in vitro. | 1. in erythrocytes of both species, deamination and phosphorylation of dado was completely inhibited by 5 microm 2'deoxycoformycin and 10 microm 5-itu respectively. 2. under physiologic conditions, provided with nanomolar concentrations of dado there was complete deamination of dado in human red cells. in opossum erythrocytes deamination and phosphorylation of the deoxynucleoside were nearly; additionally, 1-2% of the substrate was metabolized to axp. 3. with ada inhibited in intact red cells, a ... | 1993 | 8281758 |
| development of the eye in the north american opossum (didelphis virginiana). | marsupials are unique models for developmental biology-oriented research because of the immature state of their development at birth. the north american opossum (didelphis virginiana) has several advantages over other marsupials, including large litter size, short prenatal period (12.5 d), an extended postnatal period while accessible in the pouch, and its ability to reproduce reliably in captivity. studies of ocular development in this species have not been reported previously. the aim of the p ... | 1993 | 8300421 |
| intrinsic factor-cobalamin receptor activity in a marsupial, the american opossum (didelphis virginiana). | 1. significant and specific binding of intrinsic factor-cobalamin occurred in proximal but not in the distal half of the intestine in an adult marsupial, the american opossum. 2. the purified opossum kidney receptor, like rat and canine kidney receptors, revealed a single band of m(r) approximately 230 on sds-page. however, unlike the rat and canine receptors, the opossum receptor was sensitive to both endoglycosidase h and peptide-n-glycosidase f. 3. the opossum intrinsic factor-cobalamin recep ... | 1993 | 8097983 |
| characterization of mannose 6-phosphate receptors (mprs) from opossum liver: opossum cation-independent mpr binds insulin-like growth factor-ii. | bovine, human, and rat cation-independent mannose 6-phosphate receptors (ci-mprs) are capable of binding both mannose 6-phosphate and insulin-like growth factor-ii (igf-ii). however, the receptor isolated from either chicken or frog lacks the high affinity igf-ii-binding site. to determine whether ci-mprs isolated from a species that is closely related to placental mammals can bind igf-ii, the mprs were purified from a marsupial, the american opossum (didelphis virginiana), by phosphomannan-seph ... | 1993 | 8344189 |
| characterization of a marsupial sperm protamine gene and its transcripts from the north american opossum (didelphis marsupialis). | a synthetic oligonucleotide primer, designed from marsupial protamine protein-sequence data [balhorn, r., corzett, m., matrimas, j. a., cummins, j. & faden, b. (1989) analysis of protamines isolated from two marsupials, the ring-tailed wallaby and gray short-tailed opossum, j. cell. biol. 107] was used to amplify, via the polymerase chain reaction, protamine sequences from a north american opossum (didelphis marsupialis) cdna. using the amplified sequences as probes, several protamine cdna clone ... | 1993 | 8344286 |
| uroguanylin: structure and activity of a second endogenous peptide that stimulates intestinal guanylate cyclase. | the intestinal hormone guanylin and bacterial heat-stable enterotoxins (sts) are members of a peptide family that activates intestinal membrane guanylate cyclase. two different peptides that activate the human intestinal t84 cell guanylate cyclase have been purified from urine and intestinal mucosa of opossums (didelphis virginiana). the highly acidic peptide, qedcelcinvactgc, was named uroguanylin because it was isolated from urine and shares 53% identity with guanylin. a second peptide, shtcei ... | 1993 | 7902563 |
| maximum discharge rates of respiratory neurons during opossum development. | the observed low frequencies of action potentials observed in medullary respiratory neurons of immature opossums (didelphis virginiana) could occur because these cells are incapable of achieving higher sustained firing rates. nonsustainability of firing might also help explain why the inspired breath is brief (approximately 0.1 s) in the youngest opossums and rises very slowly during postnatal life. firing frequencies of medullary respiratory neurons were examined in spontaneously breathing thio ... | 1993 | 8307857 |
| development of an astrocytic response to lesions of the spinal cord in the north american opossum: an immunohistochemical study using anti-glial fibrillary acidic protein. | we have shown previously that rubral axons grow around a lesion of their pathway in developing opossums and that a critical period exists for that plasticity. the critical period begins when rubral axons first reach the level of the lesion and ends sometime between postnatal days (pd) 26 and 30. the aim of the present study was to examine the development of an astrocytic response to lesioning the spinal cord to determine if there is a temporal correlation between the development of such a respon ... | 1993 | 8244527 |
| development of radial glia and astrocytes in the spinal cord of the north american opossum (didelphis virginiana): an immunohistochemical study using anti-vimentin and anti-glial fibrillary acidic protein. | we have shown previously that rubrospinal axons grow around a lesion of their pathway in developing opossums and that a critical period exists for that plasticity. as a first step toward addressing the possibility that glial maturation and/or the development of an astrocytic response to lesioning contribute to loss of rubrospinal plasticity, we have studied the normal development of radial glia and astrocytes in the spinal cord of the opossum by immunostaining for vimentin (vim) and glial fibril ... | 1993 | 8244526 |
| morphological observations on the unique paired capillaries of the opossum retina. | light-microscopic and ultrastructural analysis of the ocular tissues of the north american opossum (didelphis virginiana) revealed that the arterial and venous segments of retinal vessels, including capillaries of the smallest calibre, occur in pairs. they do not form anastomotic networks, the common pattern in mammals with vascularised retinae, but instead the two segments of the pair join to form hairpin end loops. the paired vessels, with the arteriolar limb usually on the vitread aspect, pen ... | 1993 | 8472304 |
| the origins of descending projections to the lumbar spinal cord at different stages of development in the north american opossum. | we have employed the retrograde transport of fast blue (fb) to identify the origins of descending projections to the lumbar cord of the opossum from postnatal day (pd)1, 12-13 days after conception, to maturity. when fb injections were made into the lumbar cord at pd1, supraspinal labeling was sparse and limited to the hypothalamus, the reticular formation, the coeruleus complex, the caudal raphe, and, in one case, the interstitial nucleus of the medial longitudinal fasciculus and the lateral ve ... | 1993 | 8457879 |
| gestation and placentation in two new world opossums: didelphis virginiana and monodelphis domestica. | estrus, gestation, and placentation were studied in the virginia opossum (didelphis virginiana) and the gray short-tailed oppossum (monodelphis domestica), representatives of the prototypic, new world marsupial family didelphidae. didelphis is a large (3,000 g), pouched opossum that exhibits a 28-day estrous cycle, spontaneous estrus and ovulation, and a high ovulation rate (60 ova per cycle). monodelphis is a small (100 g), pouchless opossum with male-induced estrus and ovulation and a moderate ... | 1993 | 8371092 |
| the development of myelin in the spinal cord of the north american opossum and its possible role in loss of rubrospinal plasticity. a study using myelin basic protein and galactocerebroside immuno-histochemistry. | the aims of this study were to observe the timing and sequence of myelin formation in the opossum's spinal cord by using myelin basic protein (mbp) immuno-histochemistry and to determine whether the onset of myelination, as demonstrated by the presence of mbp or galactocerebroside (galc)-like immuno-reactivity (li), correlates temporally with the end of the critical period for rubrospinal plasticity. rubral axons grow around a lesion of their pathway during early development but they do not do s ... | 1993 | 7680969 |
| release of nitric oxide by activation of nonadrenergic noncholinergic neurons of internal anal sphincter. | the purpose of the present study was to investigate the direct release of nitric oxide (no) in response to the stimulation of nonadrenergic noncholinergic (nanc) nerves. the studies were performed on isolated smooth muscle strips of the opossum (didelphis virginiana) internal anal sphincter (ias). electrical field stimulation (efs) using the appropriate parameters caused a frequency-dependent fall in the resting tone of the ias. the release of no was measured directly by the chemiluminescence me ... | 1993 | 8430806 |
| fetal nephrotoxicity. | investigation of fetal nephrotoxicity by maternally administered nephrotoxins is hampered by many constraints, including the maternal effects of the nephrotoxin, the ability of the nephrotoxin to cross the placenta and the difficulties associated with direct fetal intervention. in the pouch young of the north american opossum, didelphis virginiana, we describe the toxic effects of a heavy metal on the immature metanephric kidneys. varying doses of uranyl nitrate, a heavy metal salt, were adminis ... | 1992 | 1640562 |
| a light-microscopic immunocytochemical study of the endocrine pancreas in the australian brush-tailed possum (trichosurus vulpecula). | the endocrine pancreas of the australian brush-tailed possum (trichosurus vulpecula) was investigated by means of immunocytochemistry using the avidin-biotin-peroxidase technique. this was a light microscopic study using this established technique. serial paraffin sections were stained individually with primary antibodies for glucagon, insulin, somatostatin, and pancreatic polypeptide (pp), showing the same islet. cells immunoreactive to glucagon, insulin, somatostatin and pp were found in endoc ... | 1992 | 1380858 |
| morphological observations on the harderian gland of the north american opossum (didelphis virginiana). | the harderian gland of the north american opossum (didelphis virginiana) is large and well developed, despite the absence of a nictitating membrane in the adult of this species. the elongate glands are surrounded by a delicate connective tissue capsule from which thin septae extend, subdividing the gland into numerous lobules. the secretory units of the opossum harderian gland are drained by a well defined but not extensive intralobular and interlobular duct system. most of the secretory end pie ... | 1992 | 1510244 |
| development of the digestive system in the north american opossum (didelphis virginiana). | 1992 | 1632285 | |
| the response of rubrospinal neurons to axotomy at different stages of development in the north american opossum. | rubral axons can grow around a lesion of their pathway in the thoracic spinal cord of developing opossums and a critical period exists for that plasticity. the critical period probably begins when rubral axons first grow into the thoracic cord, and it extends until approximately postnatal day 30. we previously noted that most rubrospinal neurons die after transection of their axon during the critical period, suggesting that plasticity results primarily from growth of axons not damaged by the les ... | 1992 | 1383556 |
| the functional morphology of xenarthrous vertebrae in the armadillo dasypus novemcinctus (mammalia, xenarthra). | in order to assess the mechanical properties of xenarthrous vertebrae, and to evaluate the role of xenarthrae as fossorial adaptations, in vitro bending tests were performed on posterior thoracic and lumbar vertebral segments excised from specimens of the armadillo dasypus novemcinctus and the opossum didelphis virginiana, the latter being used to represent the primitive mammalian condition. the columns of the two species were subjected to dorsal, ventral, and lateral bending, as well as torsion ... | 1992 | 1433308 |
| a serosurvey of swine and free-living species on iowa farms for antibodies against encephalomyocarditis virus. | swine and free-living nonporcine species from 20 iowa swine farms were surveyed for antibodies against encephalomyocarditis virus (emcv). the microtitration serum neutralization test was used, and antibody titers >/= 1:8 were considered positive. the overall prevalence in 267 sows in various groups was 37.8% (range 20-86%). the prevalence in sows maintained in total confinement was significantly lower than in sows not maintained in total confinement (p = 0.01). prevalence in sows was not associa ... | 1992 | 17424088 |
| the epidemiology of toxoplasmosis on iowa swine farms with an emphasis on the roles of free-living mammals. | multiparous sows from 19 central iowa swine farms were tested for antibodies against toxoplasma gondii by the modified direct agglutination test. antibody titers of 1:32 or greater were considered positive. rodents, domestic cats, opossums (didelphis virginiana), raccoons (procyon lotor) and striped skunks (mephitis mephitis) were live-trapped on each farm and similarly tested for antibodies. the overall prevalence of t. gondii antibodies in the species tested was 39/273 (14.3%) swine, 31/74 (41 ... | 1992 | 1496780 |
| bacterial flora of the gastrointestinal tract of opossums. | the bacterial flora of the stomach, small intestine, cecum and bile from 20 healthy opossums (didelphis virginiana) captured from the wild was studied. results showed that their gastrointestinal flora was similar to that found in other small mammals but, in addition, opossums are heavily colonized by salmonella spp., which might adversely affect their adequacy as laboratory animals for some experimental protocols. | 1992 | 1557901 |
| electrocardiographic and echocardiographic features of trypanosomiasis in dogs inoculated with north american trypanosoma cruzi isolates. | purebred beagles were inoculated with trypanosoma cruzi isolates from a north american opossum or armadillo (tc-w), and dog (tc-d). although tc-d established infection in dogs, the dogs did not develop cardiac abnormalities. dogs inoculated with tc-w developed acute myocarditis associated with increases in p-r interval, atrioventricular block, depression of r wave amplitude and shifts in mean electrical axis. echocardiograms were normal during this stage. three tc-w-inoculated dogs died during t ... | 1992 | 1586022 |
| serologic response of the opossum didelphis virginiana to a temperature-sensitive mutant (ts-4) of toxoplasma gondii. | a study was designed to measure the toxoplasma gondii-specific igm and igg antibody responses of opossums inoculated with tachyzoites of the temperature-sensitive mutant of t. gondii, ts-4, and to examine its persistence in the tissues. four young opossums seronegative for anti-toxoplasma gondii igm and igg antibodies immediately after capture and 4 wk later were injected subcutaneously with 1.8 x 10(6) ts-4 tachyzoites; a fifth opossum (also seronegative) received an injection of saline only. s ... | 1992 | 1635036 |
| retinal topography in the koala (phascolarctos cinereus). | nissl-stained retinal wholemounts were used to investigate the topographical organization of the ganglion cell layer of the koala (phascolarctos cinereus); the visual resolution limit of this animal was subsequently estimated from retinal ganglion cell density data. two types of cells could be differentiated on the basis of their size and staining characteristics: a subpopulation of presumed ganglion cells, consisting of medium to large cells with nissl substance in the cytoplasm and pale unifor ... | 1992 | 1537048 |
| immunohistochemical localization of relaxin in the reproductive system of the female opossum (didelphis virginiana). | relaxin-immunoreactivity was demonstrated in the cytoplasm in the luteal cells from pregnant and lactating opossums. immunoreactivity for relaxin was not demonstrated elsewhere in the ovary, in the reproductive tract or in the placenta. the corpus luteum is thought to be the primary source of relaxin in didelphis and in this regard is similar to several eutherian mammals including man. | 1992 | 1416066 |
| isolation from opossum serum of a metalloproteinase inhibitor homologous to human alpha 1b-glycoprotein. | fractionation of opossum (didelphis virginiana) serum with (nh4)2so4, followed by chromatography on deae-sepharose, phenyl-sepharose, and mono q hr 5/5, has resulted in the isolation in homogeneous condition of a metalloproteinase inhibitor designated oprin (opossum proteinase inhibitor). oprin is a single-chain glycoprotein (26% carbohydrate) with an estimated mr = 52,000, pi = 3.5, and e(1%/1 cm) = 11. oprin inhibited snake venom metalloproteinases, but showed no activity on venom serine prote ... | 1992 | 1731898 |
| odors as cues for orientation to mothers by weanling virginia opossums. | three experiments were conducted to investigate whether wholebody and pouch odors facilitate social cohesion between young virginia opossums and their mothers just prior to weaning. in experiment 1, young oriented toward plastic buckets containing their mothers, directing significantly higher levels of investigative behavior and more distress vocalizations toward them than toward buckets containing unrelated lactating females. in experiment 2, young oriented toward and investigated empty buckets ... | 1992 | 24254869 |
| anatomy of the bilioduodenal junction of the opossum. | prevention of reflux is a major function of the terminal biliary duct system at its junction with the duodenum. we examined this area via scanning electron microscopy and light microscopy to explore anatomic features that might play such a role in the virginia opossum, a species with a highly developed sphincter of oddi (so). the terminal apparatus, most of which consists of a dilated extramural ampulla, has a lumen with abundant folds. mucus is produced by the lining epithelium and by a plethor ... | 1992 | 1554107 |
| organization of midbrain catecholamine-containing nuclei and their projections to the striatum in the north american opossum, didelphis virginiana. | presumptive catecholamine (ca) neurons in the opossum midbrain were identified by tyrosine hydroxylase immunohistochemistry. in the midline, small to moderate number of ca cells were present in the rostral third of the nucleus raphe dorsalis and throughout the nucleus linearis. ventrolaterally, such cells were observed in the deep tegmental reticular formation, in all subnuclei of the ventral tegmental area, and in the three subdivisions of the substantia nigra. the ca cells in these areas confo ... | 1991 | 1677010 |
| deoxyadenosine triphosphate acting as an energy-transferring molecule in adenosine deaminase inhibited human erythrocytes. | deoxyadenosine triphosphate (datp) is present in adenosine deaminase (ada)-deficient or ada-inhibited human red cells and in the red cells of the opossum didelphis virginiana. in order to investigate the functions of datp in the red cell, red cells were treated with 2'-deoxycoformycin (dcf), a powerful inhibitor of ada, and incubated with phosphate, deoxyadenosine and glucose. these red cells in which atp was almost completely replaced by datp, had the same shape, lactate production, nucleotide ... | 1991 | 1911876 |
| salmonella infection of the biliary and intestinal tract of wild opossums. | bacteriologic cultures were taken from the mesenteric lymph nodes, biliary tract, blood, liver, spleen and pancreas of opossums (didelphis virginiana) obtained directly from the wild for use as research animals. the overall incidence of salmonellosis outside the intestinal tract was 61% among 18 opossums. salmonella was recovered from the gallbladder of six (33%) animals, indicating chronic biliary tract infection. among these six animals, translocation of salmonella to regional lymph nodes was ... | 1991 | 1849588 |
| natural anti-snake venom proteins. | the resistance of several animals to snake venom has been reviewed. some general concepts are introduced to allow the comparative evaluation of the resistance of different animals studied by different investigators. the purification and properties of several factors isolated from the serum of different animals by some researchers are described: trimeresurus flavoviridis (omori-satoh et al., 1972); vipera palaestinae (ovadia et al., 1975, 1977); sigmodon hispidus (pichyangkul and perez, 1981); di ... | 1991 | 1801313 |
| hypertrophic smooth muscle in the partially obstructed opossum esophagus. the model: histological and ultrastructural observations. | obstruction is a complication of many esophageal diseases, but the morphological changes occurring in the obstructed esophagus are poorly understood. we developed a model of esophageal obstruction in the american opossum, didelphis virginiana. a nonconstricting band around the gastroesophageal junction led to esophageal distention and tortuosity in the weeks following its placement. despite a marked increase of the esophageal circumference, the esophageal wall was not thinned, and the circular m ... | 1991 | 2001825 |
| lung lesions in an opossum (didelphis virginiana) associated with capillaria didelphis. | an opossum (didelphis virginiana) live-trapped on parramore island, virginia was infected with the lung parasite capillaria didelphis. lung lesions associated with this parasite were extensive and consisted of numerous areas with central necrosis deep within the parenchyma. necrotic foci were present around airways and consisted of a mixture of inflammatory cells and cellular debris, adult nematodes and many bipolar eggs. this parasite causes severe verminous pneumonia in the opossum. | 1991 | 2023321 |
| effects of hydrocortisone acetate treatment on the small intestine of the lactent marsupial didelphis albiventris. | when hydrocortisone acetate was administered subcutaneously to the lactent brazilian white belly opossum, it induced precocious intestinal maturation. histological features of the small intestine were reminiscent of those seen in human protein-caloric malnutrition. there were also indications that the glucocorticoid acted as an inducer of the differentiation of paneth, goblet and granulomucous cells within the small intestinal epithelium. in the lactent opossum the small intestine is lined by an ... | 1991 | 2064018 |
| the origins of supraspinal projections to lumbosacral and cervical levels of the spinal cord in the gray short-tailed brazilian opossum, monodelphis domestica. | retrograde tracing techniques were used to identify supraspinal neurons that project to sacral, lumbar and cervical levels of the spinal cord in the gray short-tailed brazilian opossum, monodelphis domestica. injections of fast blue, true blue or wheat germ agglutinin conjugated to horseradish peroxidase into the sacral or lumbar cord labeled neurons in hypothalamic and brainstem nuclei reported to innervate the same levels in other mammals. injections at cervical levels produced extensive label ... | 1991 | 1684917 |
| evidence for new growth and regeneration of cut axons in developmental plasticity of the rubrospinal tract in the north american opossum. | we have shown previously that rubral axons can grow around a lesion of their spinal pathway in the developing opossum and that a critical period exists for that plasticity (martin and xu, dev brain res 39:303, 1988). since most rubrospinal neurons degenerate after axotomy during the critical period, we have proposed that plasticity results primarily from growth of late arriving axons around the lesion rather than regeneration of cut axons (xu and martin, j comp neurol 279:368, 1989). in the pres ... | 1991 | 1761748 |
| physiological interactions between enkephalin and excitatory amino acids in the cerebellar cortex of the opossum didelphis marsupialis virginiana. | the opiate peptide enkephalin has been immunohistochemically localized within specific populations of climbing fibers and mossy fibers in the opossum's cerebellum. the intention of the present study was to determine the physiological effects of this peptide on purkinje cell activity as well as to examine interactions between this peptide and the excitatory amino acids glutamate and aspartate. iontophoretic application of enkephalin onto purkinje cells in the posterior lobe vermis and adjacent he ... | 1991 | 1682851 |
| the origin of serotoninergic projections to the lumbosacral spinal cord at different stages of development in the north american opossum. | we have employed immunohistochemistry and the retrograde transport of fast blue to study the origin of serotoninergic projections to the lumbosacral spinal cord at different stages of development in the north american opossum. a few serotoninergic axons are present in the lumbosacral cord at birth, 12 days after conception, and serotoninergic neurons are numerous in the brainstem where they are present in most, if not all, of the areas which contain them in the adult animals. a few neurons of th ... | 1991 | 1851469 |
| mammary glands in male marsupials. 2. development of teat primordia in didelphis virginiana and monodelphis domestica. | young and adults of both sexes of two didelphid marsupials, didelphis virginiana and monodelphis domestica, were examined externally for evidence of mammary gland development. female young possessed teat numbers typical of adult females (13-15 in d. virginiana; 11-13 in m. domestica). male young showed variable teat numbers which were always low compared with females, with the majority possessing 2-4 in anterior positions. teats were also present in adult males of both species, in similar number ... | 1991 | 1947228 |
| nad synthesis in ada deficient erythrocytes of the opossum didelphis virginiana. | 1991 | 1781390 | |
| the vestibular apparatus of the opossum (didelphis virginiana) prior to and immediately after birth. | the vestibular apparatus of the opossum was examined shortly before and immediately after birth. a band of about 20 sensory cells was observed within the forming utricle by 24 h prior to birth. stereocilia projecting from the apices of the sensory cells appeared intimately associated with a well-defined population of overlying otoliths. these morphological observations suggest that a functional utricle may be present at the time of birth and together with other senses (tactile, olfaction) may ai ... | 1991 | 1781240 |
| mammary glands in male marsupials: i. primordia in neonatal opossums didelphis virginiana and monodelphis domestica. | neonates of the american didelphid marsupials didelphis virginiana and monodelphis domestica were sexed by karyotype and histologically examined on the day of birth. mammary anlagen were found in both sexes of both species, but the neonatal males had less than one-third of the full female complement of mammary glands. male neonates of both species also had paired scrotal bulges anterior to the genital tubercle but these were never present in females, once again raising the question of whether th ... | 1990 | 2133544 |
| studies on the energy metabolism of opossum (didelphis virginiana) erythrocytes: v. utilization of hypoxanthine for the synthesis of adenine and guanine nucleotides in vitro. | high pressure liquid radiochromatography was used to test the ability of opossum erythrocytes to incorporate tracer amounts of [g-3h] hypoxanthine (hy) into [3h] labelled triphosphates of adenine and guanine. in the presence of supraphysiologic (30 mm) phosphate which is optimal for prpp synthesis, both atp and gtp are extensively labelled. when physiologic (1 mm) medium phosphate is used, red cells incubated under an atmosphere of nitrogen accumulate [3h] atp in a linear fashion suggesting ongo ... | 1990 | 2358475 |
| origins and terminations of bulbospinal axons that contain serotonin and either enkephalin or substance-p in the north american opossum. | we have shown previously that some enkephalin, substance-p, and serotoninergic neurons in the medullary raphe and adjacent reticular formation project to the spinal cord in the opossum. in the present study we have combined the retrograde transport of true blue and immunofluorescence histochemistry to determine whether methionine enkephalin or substance-p containing bulbospinal neurons are serotoninergic. furthermore, we have used the same immunofluorescence protocol to determine whether spinal ... | 1990 | 1691216 |
| development of catecholaminergic projections to the spinal cord in the north american opossum, didelphis virginiana. | the intent of our study was to determine when catecholaminergic axons grow into each of their adult targets in the spinal cord of the north american opossum (didelphis virginiana) and to identify the origin of catecholaminergic axons in the lumbosacral cord at different stages of development. tyrosine hydroxylase-like immunoreactive axons, presumed to be catecholaminergic, were demonstrated at different stages of development by the indirect antibody peroxidase-antiperoxidase technique of sternbe ... | 1990 | 1971285 |
| the response of rubrospinal neurons to axotomy in the adult opossum, didelphis virginiana. | to provide endpoints for developmental studies of rubrospinal plasticity in the north american opossum, we have attempted to determine the degree to which rubrospinal neurons survive axotomy in the adult animal. bilateral or unilateral injections of the long-lasting fluorescent marker fast blue were made into the t-10 or the t-11 segment of the spinal cord to label rubrospinal neurons, and 7 days later, the rubrospinal tract was cut unilaterally four segments rostral to the injection(s). in case ... | 1990 | 2318287 |
| morphological organization of thalamocortical relay cells in the dorsal lateral geniculate nucleus of the north american opossum. | the morphology of relay cells in the dorsal lateral geniculate nucleus of the north american opossum was studied by using both golgi-cox material and cells stained from retrograde transport of horseradish peroxidase. in general, soma sizes were largest in the part of the nucleus representing the central retina and decreased from the middle third of the nucleus to the anterior to posterior poles. relay cells labeled with horseradish peroxidase were found to constitute approximately 90% of the dor ... | 1990 | 2319015 |
| opossum (didelphis virginiana) "little" and "big" gastrins. | 1. "little" gastrins from most mammalian species are 17 amino acid peptides and the precursor "big" gastrins are 34 amino acid peptides. 2. "little" gastrins of the new world hystricomorphs, guinea-pig and chinchilla, are 16 amino acid peptides due to deletion of a glutamic acid in the region 6-9 from their nh2-terminus and the corresponding "big" gastrins are 33 amino acid peptides. 3. antral gastrins from the opossum, a new world marsupial, have a glutamic acid deletion in the same region as t ... | 1990 | 2361360 |
| autoradiographic demonstration of specific binding sites for e. coli enterotoxin in various epithelia of the north american opossum. | in the north american opossum, heat-stable specific binding sites for e. coli enterotoxin are observed (i) in epithelial cells lining the small intestine, colon, gall bladder, cystic duct, common bile duct and trachea, and (ii) in epithelial cells forming the duodenal (brunner's) glands, liver, kidneys (metanephros, mesonephros) and testis, as demonstrated by autoradiography. enterotoxin-specific binding sites in the intestinal tract are only found in intestinal epithelial cells with the highest ... | 1990 | 2162736 |
| aerobic bacteria cultured from the mouth of the american opossum (didelphis virginiana) with reference to bacteria associated with bite infections. | the american opossum inflicts bite injuries both when hunted for food and when accidentally provoked when handled in captivity. this study involved aerobically culturing organisms from the mouths of seven wild opossums (didelphis virginiana). isolates included streptococci, coagulase-positive and -negative staphylococci, aeromonas spp., citrobacter freundii, eikenella corrodens, and escherichia coli. | 1990 | 2229365 |
| host-dependent differences in feeding and reproduction of ixodes dammini (acari: ixodidae). | the frequencies with which adult ixodes dammini spielman, clifford, piesman and corwin feed upon white-tailed deer (odocoileus virginianus), raccoons (procyon lotor), opossums (didelphis virginiana), and domestic cats were compared in a wooded site in northeastern united states. by combining estimates of the quantity of ticks feeding on each host species with host densities, we derived the relative contribution made by each kind of host to the feeding of the tick population. to compare engorgeme ... | 1990 | 2280395 |
| the lamina propria of vertebrate seminiferous tubules: a comparative light and electron microscopic investigation. | the lamina propria of the seminiferous tubules was compared by means of light and electron microscopy in specimens obtained from the following vertebrates: mute swan, northern mallard, blackbird, grey short-tailed opossum, north american opossum, european rabbit, mouse, rat, golden hamster, mini pig, bull, llama, roebuck, horse, coati, cat, dog, java monkey, orang utan. the lamina propria consists of basal lamina, ground substance, collagen fibers, fibroblasts and myofibroblasts. myofibroblasts ... | 1990 | 2281881 |
| vascular and avascular retinae in mammals. a funduscopic and fluorescein angiographic study. | intraretinal blood vessels are present in some and absent in other vertebrate species, including the mammals. among the marsupials, both vascular and avascular retinae are seen. we determined the funduscopic appearance of the eye, investigated the functional aspects of ocular blood flow in both types of retina in marsupials and compared our results with known patterns in placental mammals. the australian polyprotodont marsupials, the tasmanian devil, sarcophilus harrisii, and the quoll, dasyurus ... | 1990 | 2375974 |
| ectoparasitic and phoretic arthropods of virginia opossums (didelphis virginiana) in central tennessee. | thirteen species of ectoparasitic (12) or phoretic (1) arthropods were collected from 26 adult virginia opossums, didelphis virginiana, live-trapped from april through september 1987 in davidson county, tennessee. the cat flea ctenocephalides felis and the american dog tick dermacentor variabilis were the predominant species with respect to mean intensity and prevalence. the macronyssid mite ornithonyssus wernecki and the atopomelid mite didelphilichus serrifer, both specific parasites of this h ... | 1990 | 2380870 |
| the role of medium-sized mammals as reservoirs of borrelia burgdorferi in southern new york. | the ability of raccoons (procyon lotor), striped skunks (mephitis mephitis) and opossums (didelphis virginiana) to serve as reservoirs of borrelia burgdorferi, the spirochetal agent of lyme disease, was compared with that of white-footed mice (peromyscus leucopus). twenty-eight (28) medium-sized mammals and 34 white-footed mice were captured in westchester county, new york (usa) in summer 1986. animals were caged over pans of water for 1 to 2 days to recover engorged tick larvae (ixodes dammini) ... | 1990 | 2388356 |
| characterization of the muscarinic cholinergic receptor in the opossum (didelphis virginiana, kerr) submandibular gland: differences in receptor density and subtype compared with higher mammalian species. | 1. kinetic, saturation and inhibition radioligand binding experiments with [3h]-n-methylscopolamine and [3h]quinuclidinyl benzilate were used to characterize the muscarinic cholinergic receptor in opossum (didelphis virginiana, kerr) submandibular salivary gland membranes. 2. the receptor density in opossum submandibular gland was found to be more than 3-fold higher than in rat, and 22-fold higher than in human, submandibular glands. 3. inhibitor equilibrium dissociation constants for the antago ... | 1990 | 1981346 |
| pulmonary reflexes and breathing pattern during sleep in the opossum. | paradoxical sleep (ps) in the opossum (didelphis virginiana) and other mammals is typically accompanied by irregular breathing, while even breathing is usually found during slow wave sleep (sws). during ps certain brainstem reflexes are depressed, and it is possible that similar depression of pulmonary reflexes could contribute to the observed ventilatory uneveness. to test this possibility, we assessed pulmonary reflexes in the opossum during sws and during ps when breathing was irregular. prol ... | 1990 | 184508 |
| host associations of ticks (acari: ixodidae) parasitizing medium-sized mammals in a lyme disease endemic area of southern new york. | ticks of eight medium-sized mammal species were studied in an area of endemic lyme disease in westchester county, n.y., from 1 april 1984 to 31 march 1985. most (81%) of the 266 total mammal captures were raccoon, procyon lotor (l.) (47%), opossum, didelphis virginiana (kerr) (19%), and striped skunk, mephitis mephitis schreber (15%); these host species accounted for 91% of the 1,519 ticks collected. although the total number of ticks was rather evenly distributed among these mammals, species co ... | 1989 | 2724317 |
| a cyto-architectonic description of the thalamus of the tammar wallaby, macropus eugenii. | very few studies are available on the cyto-architectural features of the thalamus of metatherian mammals. most of these studies describe the thalamus of a polyprotodont metatherian, the north american opossum, didelphis virginiana. studies on diprotodont metatherians are fewer still. there are two descriptions of the thalamus of the australian possum trichosurus vulpecula. the only part of the thalamus that has been described in the wallabies is the lateral geniculate nucleus. hence, there was a ... | 1989 | 2765853 |