Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| seroprevalence of trypanosoma cruzi in raccoons from south carolina and georgia. | trypanosoma cruzi, the causative agent of american trypanosomiasis or chagas' disease, is of both medical and veterinary importance as is evidenced by chronic phase myocarditis in humans and dogs. further, t. cruzi has been reported from over 20 species of wildlife reservoir hosts in the usa, with raccoons (procyon lotor) and opossums (didelphis virginiana) being the most common. whereas previous studies on t. cruzi in raccoons have included only culture and direct examination of blood, the indi ... | 2002 | 11838232 |
| spontaneous squamous cell carcinoma of the tongue and multiple bronchioloalveolar carcinomas in a virginia opossum (didelphis virginiana). | two primary tumours, squamous cell carcinoma of the tongue and multiple bronchioloalveolar carcinomas, were diagnosed in a virginia opossum (didelphis virginiana). two oral masses were located in the right ventrolateral surface of the tongue, near the frenulum, and the lungs contained multiple, widely distributed, nodular masses. microscopically, the oral masses were composed of invasive cords of pleomorphic, polyhedral cells, typical of squamous cells. the multiple pulmonary masses consisted of ... | 2002 | 11945013 |
| experimental inoculation of north american opossums (didelphis virginiana) with mycobacterium bovis. | eight north american opossums (didelphis virginiana) were inoculated with 1 x 10(5) colony forming units of mycobacterium bovis to investigate their potential as reservoir hosts for bovine tuberculosis in michigan. four animals received this dose orally and four were inoculated intramuscularly (i.m.). in each group, two animals were euthanized 1 mo postinoculation (pi) and two at 2 mo pi. four control animals were housed separately and sacrificed in the same manner as those inoculated. one of fo ... | 2002 | 12038125 |
| sarcocystis meningoencephalitis in a northern gannet (morus bassanus). | sarcocystis sp. schizonts were found in the cerebellum of a northern gannet (morus bassanus), exhibiting neurologic signs, found on the florida (usa) east coast. based upon molecular characterization of dna isolated from the brain of the gannet, this sarcocystis sp. appeared to be closely related, if not identical, to an unnamed sarcocystis sp. typified by isolates 1085 and 1086 collected from feces of a virginia opossum (didelphis virginiana) on the east coast of florida. because the life cycle ... | 2002 | 12038144 |
| 'candidatus mycoplasma haemodidelphidis' sp. nov., 'candidatus mycoplasma haemolamae' sp. nov. and mycoplasma haemocanis comb. nov., haemotrophic parasites from a naturally infected opossum (didelphis virginiana), alpaca (lama pacos) and dog (canis familiaris): phylogenetic and secondary structural relatedness of their 16s rrna genes to other mycoplasmas. | the 16s rrna sequence of newly characterized haemotrophic bacteria in an opossum (didelphis virginiana) and alpaca (lama pacos) was determined. in addition, the 16s rrna sequence of a haemotrophic parasite in the dog (canis familiaris) was determined. sequence alignment and evolutionary analysis as well as secondary structural similarity and signature nucleotide sequence motifs of their 16s rrna genes, positioned these organisms in the genus mycoplasma. the highest scoring sequence similarities ... | 2002 | 12054227 |
| porrorchis nickoli n. sp. (acanthocephala:: plagiorhynchidae) from mammals in southeastern mexico, first known occurrence of porrorchis in the western hemisphere. | porrorchis nickoli n. sp. is described from the intestine of the gray four-eyed opossum philander opossum (type host), the virginia opossum didelphis virginiana, the common opossum didelphis marsupialis, and the white-nosed coati nasua narica. hosts were collected in southeastern mexico in the los tuxtlas region of the state of veracruz (type locality) and in the states of tabasco and chiapas. this new species is distinguished from other porrorchis species by its small proboscis (0.286-0.428 mm ... | 2002 | 12058721 |
| experimental inoculation of domestic cats (felis domesticus) with sarcocystis neurona or s. neurona-like merozoites. | sarcocystis neurona is the parasite most commonly associated with equine protozoal myeloencephalitis (epm). recently, cats (felis domesticus) have been demonstrated to be an experimental intermediate host in the life cycle of s. neurona. this study was performed to determine if cats experimentally inoculated with culture-derived s. neurona merozoites develop tissue sarcocysts infectious to opossums (didelphis virginiana), the definitive host of s. neurona. four cats were inoculated with s. neuro ... | 2002 | 12072209 |
| establishment of besnoitia darlingi from opossums (didelphis virginiana) in experimental intermediate and definitive hosts, propagation in cell culture, and description of ultrastructural and genetic characteristics. | besnoitia darlingi from naturally infected opossums (didelphis virginiana) from mississippi, usa, was propagated experimentally in mice, cats, and cell culture and was characterised according to ultrastructural, genetic, and life-history characteristics. cats fed tissue cysts from opossums shed oocysts with a prepatent period of nine or 11 days. oocysts, bradyzoites, or tachyzoites were infective to outbred and interferon-gamma gene knockout mice. tachyzoites were successfully cultivated and mai ... | 2002 | 12076634 |
| isolation of salmonella enterica and serologic reactivity to leptospira interrogans in opossums (didelphis virginiana) from yucatán, méxico. | the presence of salmonella enterica and serologic evidence of infection by leptospira interrogans, were detected in the opossum didelphis virginiana in a semi-urban locality of the yucatán state, méxico. ninety-one opossums were captured during the period april 1996 and may 1998. from a total of 17 feces samples, four salmonella enterica subsp. enterica serotypes (sandiego, newport, anatum, and minnesota), and one salmonella enterica subsp. arizonae serovar o44:z4,z23:- were isolated. some oposs ... | 2002 | 12219118 |
| the opossum didelphis virginiana as a synanthropic reservoir of trypanosoma cruzi in dzidzilché, yucatán, méxico. | in méxico, the role of mammals in the transmission cycle of trypanosoma cruzi is poorly known. in the state of yucatán, an endemic area of chagas disease, both didelphis virginiana and d. marsupialis occur sympatrically. however, until now, only the former species had been found infected with t. cruzi. to evaluate the role of d. virginiana in a peridomestic transmission, nine periods of capture-recapture were performed around the village of dzidzilché, yucatán. the sex, age, reproductive status, ... | 2002 | 12219121 |
| a retrospective study of 11 cases of lungworm (didelphostrongylus hayesi) infection in opossums (didelphis virginiana). | a juvenile, female north american opossum (didelphis virginiana) died of verminous pneumonia caused by didelphostrongylus haysei despite aggressive treatment with oral fenbendazole, corticosteroids, and antibiotics. this prompted a retrospective study of lungworm infection in opossums, during which 19 additional necropsy reports from opossums were reviewed. including the subject of this report, a total of 11 (55%) of these cases included a diagnosis of lungworm infection. this diagnosis was cons ... | 2002 | 12398306 |
| parastrongylus (=angiostrongylus) cantonensis now endemic in louisiana wildlife. | parastrongylus (=angiostrongylus) cantonensis, a lung worm of rats, was first reported in the united states in 1987, with a probable introduction by infected rats from ships docking in new orleans, louisiana, during the mid-1980s. since then, it has been reported in nonhuman primates and a boy from new orleans, and in a horse from picayune, mississippi, a distance of 87 km from new orleans. parastrongylus cantonensis infection is herein reported in a lemur (varencia variegata rubra) from new ibe ... | 2002 | 12435151 |
| prevalence of agglutinating antibodies to sarcocystis neurona in skunks (mephitis mephitis), raccoons (procyon lotor), and opossums (didelphis virginiana) from connecticut. | equine protozoal myeloencephalitis is the most important protozoan disease of horses in north america and is usually caused by sarcocystis neurona. natural cases of encephalitis caused by s. neurona have been reported in skunks (mephitis mephitis) and raccoons (procyon lotor). opossums (didelphis spp.) are the only known definitive host. sera from 24 striped skunks, 12 raccoons, and 7 opossums (d. virginiana) from connecticut were examined for agglutinating antibodies to s. neurona using the s. ... | 2002 | 12435152 |
| normal conjunctival flora in the north american opossum (didelphis virginiana) and raccoon (procyon lotor). | we documented the normal conjunctival bacterial flora from 17 opossums (didelphis virginiana) and 10 raccoons (procyon lotor) trapped in manhattan, kansas (usa) from november 1999 to january 2000. both raccoons and opossums were free of apparent ocular disease. the inferior conjunctival sacs of each animal were swabbed for aerobic bacterial and mycoplasma culture and polymerase chain reaction (pcr) for mycoplasma and chlamydia detection. all conjunctival samples were positive for one or more spe ... | 2002 | 12528457 |
| prevalence and site specificity of sarcocystis greineri sarcocysts in virginia opossum (didelphis virginiana) in florida. | sarcocysts of sarcocystis greineri in the virginia opossum (didelphis virginiana) were observed for documenting sarcocyst prevalence, seasonal prevalence, and muscle specificity. characteristics of sarcocysts found in striated muscle were recorded, as were light microscopy measurements. overall prevalence of sarcocysts in striated muscle was 10.0% (24/240). no statistical difference (p = 0.156) in prevalence was detected between summer (13.1%; 16/122) and fall (6.7%; 8/118). sarcocysts were foun ... | 2002 | 12099438 |
| molecular systematics of sciurognathi (rodentia): the mitochondrial cytochrome b and 12s rrna genes support the anomaluroidea (pedetidae and anomaluridae). | nucleotide sequence data from the mitochondrial 12s rrna and cytochrome b genes were used to analyze phylogenetic relationships among sciurognath rodents. our sample taxa included representatives of 11 sciurognath and 3 hystricognath families with two marsupial species, didelphis virginiana and macropus robustus, as outgroups. the dataset was analyzed using both maximum-parsimony (weighted and unweighted) and likelihood methods. three suprafamilial groupings are strongly supported: geomyidae + h ... | 2002 | 11820843 |
| the effects of western diamondback rattlesnake (crotalus atrox) venom on the production of antihemorrhagins and/or antibodies in the virginia opossum (didelphis virginiana). | opossums are animals that are naturally resistant to the proteolytic effects of crotalid venoms. opossums possess proteinase inhibitors in their sera that bind to and neutralize hemorrhagic and other proteolytic activity in many snake venoms. the proteinase inhibitors are not antibodies since they have different molecular weights (60kda) and pi (4.2). the purpose of this study was to determine if opossums were capable of producing antibodies against venom and/or increasing the production of prot ... | 2002 | 11738236 |
| scanning electron microscopy of turgida turgida (nematoda: spiruroidea), parasite of the virginia opossum, didelphis virginiana, from southern california. | taxonomic characters for identification of turgida turgida rudolphi, 1819, a parasitic nematode of the virginia opossum didelphis virginiana, were studied by scanning electron microscopy. the distinguishing feature of the cephalic end is the presence of numerous denticles, structures associated with the internal tooth, and 2 spongelike areas on the inner side of each pseudolabia. the posterior end of male t. turgida differs from that in other species of physalopteridae by the number of caudal pa ... | 2001 | 11695400 |
| mitochondrial genomes of a bandicoot and a brushtail possum confirm the monophyly of australidelphian marsupials. | recent molecular analyses suggest that the position of bandicoots is the major difficulty in determining the root of the tree of extant marsupials. to resolve this, we analyse mitochondrial genome sequences of a bandicoot (isoodon macrourus) and a brushtail possum (trichosurus vulpecula) together with the previously available marsupial mitochondrial genomes, the virginia opossum (didelphis virginiana) and the wallaroo (macropus robustus). analyses of mitochondrial protein-coding and rna genes st ... | 2001 | 11454299 |
| the striped skunk (mephitis mephitis) is an intermediate host for sarcocystis neurona. | striped skunks, initially negative for antibodies to sarcocystis neurona, formed sarcocysts in skeletal muscles after inoculation with s. neurona sporocysts collected from a naturally infected virginia opossum (didelphis virginiana). skunks developed antibodies to s. neurona by immunoblot and muscles containing sarcocysts were fed to laboratory-reared opossums which then shed sporulated sarcocystis sporocysts in their faeces. mean dimensions for sporocysts were 11.0 x 7.5 microm and each contain ... | 2001 | 11403777 |
| viability of sarcocystis neurona sporocysts and dose titration in gamma-interferon knockout mice. | gamma-interferon knockout mice have become the model animal used for studies on sarcocystis neurona. in order to determine the viability of s. neurona sporocysts and to evaluate the course of the disease in these mice, sporocysts were collected from opossums (didelphis virginiana), processed, and stored for varying periods of time. gamma-interferon knockout mice were then inoculated orally with different isolates at different doses. these animals were observed daily for clinical signs until they ... | 2001 | 11223202 |
| evaluation of the shedding of sarcocystis falcatula sporocysts in experimentally infected virginia opossums (didelphis virginiana). | five virginia opossums (didelphis virginiana) were fed muscles of brown-headed cowbirds (molothrus ater) containing sarcocysts of sarcocystis falcatula. shedding of sporocysts was confirmed in all five opossums by fecal flotation. counts were conducted daily for 2 weeks and then biweekly until the animals were euthanized and necropsied. the average prepatent period was 9.8 (7-16) days. the number of sporocysts shed varied greatly between the opossums with maximum mean shedding occurring at 71.6 ... | 2001 | 11223211 |
| development of sarcocystis falcatula in its intermediate host, the brown-headed cowbird (molothrus ater). | sporocysts of sarcocystis falcatula obtained from experimentally infected virginia opossums (didelphis virginiana) were inoculated orally to 60 wild-caught brown-headed cowbirds (molothrus ater). another 30 brown-headed cowbirds were not challenged and served as uninfected controls. two inoculated and one control cowbird were necropsied every 2 weeks and the pectoral and thigh muscles were examined grossly for cyst development. stained histologic sections of pectoral muscle, thigh muscle, and lu ... | 2001 | 11223213 |
| bovine tuberculosis in free-ranging carnivores from michigan. | during a survey of carnivores and omnivores for bovine tuberculosis conducted in michigan (usa) since 1996, mycobacterium bovis was cultured from lymph nodes pooled from six coyotes (canis latrans) (four adult female, two adult male), two adult male raccoons (procyon lotor), one adult male red fox (vulpes vulpes), and one 1.5-yr-old male black bear (ursus americanus). one adult, male bobcat (felis rufus) with histologic lesions suggestive of tuberculosis was negative on culture but positive for ... | 2001 | 11272505 |
| the nine-banded armadillo (dasypus novemcinctus) is an intermediate host for sarcocystis neurona. | the nine-banded armadillo (dasypus novemcinctus) is an intermediate host of at least three species of sarcocystis, sarcocystis dasypi, sarcocystis diminuta, and an unidentified species; however, life cycles of these species have not been determined. following feeding of armadillo muscles containing sarcocysts to the virginia opossum (didelphis virginiana), the opossums shed sporulated sarcocystis sporocysts in their faeces. mean dimensions for sporocysts were 11.0x7.5 microm and each contained f ... | 2001 | 11306111 |
| spotted fever group rickettsia in dermacentor variabilis (acari: ixodidae) infesting raccoons (carnivora: procyonidae) and opossums (marsupialia: didelphimorphidae) in tennessee. | spotted fever group rickettsia were present in 13 of 1,171 (1.1%) of adult dermacentor variabilis say removed from raccoons (procyon lotor l.) and virginia opossums (didelphis virginiana kerr) in western tennessee. spotted fever group rickettsia were detected by amplification of a 617-bp segment of the citrate synthase gene by polymerase chain reaction. | 2001 | 11476343 |
| sarcocystis greineri n. sp. (protozoa: sarcocystidae) in the virginia opossum (didelphis virginiana). | sarcocysts were found in the skeletal muscles of road-killed and live-trapped opossums collected in north central florida. sarcocysts were spindle-shaped and macroscopic and had an average measurement of 3.8 mm by 154.6 microm. sarcocysts were only observed in skeletal muscle. sarcocysts have invaginations throughout the sarcocyst wall, which is approximately 1 microm thick. protrusions on the sarcocyst wall are stumpy and digitlike and contain fibrillar elements that extend from the interior po ... | 2001 | 11695370 |
| sarcocystis neurona infections in raccoons (procyon lotor): evidence for natural infection with sarcocysts, transmission of infection to opossums (didelphis virginiana), and experimental induction of neurologic disease in raccoons. | equine protozoal myeloencephalitis (epm) is a serious neurologic disease of horses in the americas and sarcocystis neurona is the most common etiologic agent. the distribution of s. neurona infections follows the geographical distributions of its definitive hosts, opossums (didelphis virginiana, didelphis albiventris). recently, cats and skunks were reported as experimental and armadillos as natural intermediate hosts of s. neurona. in the present report, raccoons (procyon lotor) were identified ... | 2001 | 11698157 |
| comparative pathology and pathogenesis of naturally acquired and experimentally induced colonic spirochetosis. | research in the past decade has led to the recognition of brachyspira (formerly serpulina) pilosicoli as the primary etiologic agent of colonic spirochetosis (cs), an emerging cause of colitis in humans and animals. attachment of spirochetes to the epithelial surface of the lower intestine is considered to be the hallmark of cs. however, because b. pilosicoli, b. aalborgi and unclassified flagellated bacteria are found singly or together in humans and non-human primates with cs lesions, attachme ... | 2001 | 11708743 |
| risk factors associated with the presence of sarcocystis neurona sporocysts in opossums (didelphis virginiana). | sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (epm) in horse in the americas. the only known definitive host for this parasite in the united states is the opossum (didelphis virginiana); however, despite the importance of the disease, the epidemiology of the parasite in the definitive host is poorly understood. to begin addressing these data gaps, potential risk factors were evaluated for their association with the presence of sporocysts of s. neurona in o ... | 2001 | 11777597 |
| sarcocystis neurona infections in sea otter (enhydra lutris): evidence for natural infections with sarcocysts and transmission of infection to opossums (didelphis virginiana). | although sarcocystis neurona has been identified in an array of terrestrial vertebrates, recent recognition of its capacity to infect marine mammals was unexpected. here, sarcocysts from 2 naturally infected sea otters (enhydra lutris) were characterized biologically, ultrastructurally, and genetically. dna was extracted from frozen muscle of the first of these sea otters and was characterized as s. neurona by polymerase chain reation (pcr) amplification followed by restriction fragment length p ... | 2001 | 11780826 |
| acute pulmonary sarcocystis falcatula-like infection in three victoria crowned pigeons (goura victoria) housed indoors. | three free-roaming victoria crowned pigeons (goura victoria) housed in a completely enclosed tropical exhibit were found dead without antemortem signs of illness. the birds died within 9 days of each other. gross necropsy revealed moderate pulmonary edema in all three birds. histopathologic examination revealed pulmonary edema and pulmonary protozoal merozoites compatible with sarcocystis spp., toxoplasma gondii, or neospora spp. infection. immunohistochemical staining for t. gondii and neospora ... | 2001 | 12790430 |
| the seroprevalence of antibodies to sarcocystis neurona in michigan equids. | a cross-sectional study of serum antibodies to sarcocystis neurona (the etiologic agent of equine protozoal myeloencephalitis, epm) was performed on michigan equids. our objectives were to determine the seroprevalence of antibodies to s. neurona in michigan equids and to identify specific risk factors for seropositivity. a random, weighted sample of michigan horse farms (stratified by the state's opossum (didelphis virginiana) population and the number of equids on each operation) was selected. ... | 2001 | 11154784 |
| a review of sarcocystis neurona and equine protozoal myeloencephalitis (epm). | equine protozoal myeloencephalitis (epm) is a serious neurological disease of horses in the americas. the protozoan most commonly associated with epm is sarcocystis neurona. the complete life cycle of s. neurona is unknown, including its natural intermediate host that harbors its sarcocyst. opossums (didelphis virginiana, didelphis albiventris) are its definitive hosts. horses are considered its aberrant hosts because only schizonts and merozoites (no sarcocysts) are found in horses. epm-like di ... | 2001 | 11223193 |
| immunoconversion against sarcocystis neurona in normal and dexamethasone-treated horses challenged with s. neurona sporocysts. | equine protozoal myeloencephalitis is a common neurologic disease of horses in the americas usually caused by sarcocystis neurona. to date, the disease has not been induced in horses using characterized sporocysts from didelphis virginiana, the definitive host. s. neurona sporocysts from 15 naturally infected opossums were fed to horses seronegative for antibodies against s. neurona. eight horses were given 5x10(5) sporocysts daily for 7 days. horses were examined for abnormal clinical signs, an ... | 2001 | 11223200 |
| prevalence of neospora hughesi and sarcocystis neurona antibodies in horses from various geographical locations. | parasite-specific antibody responses to neospora antigens were detected using the immunofluorescent antibody test (ifat) and immunoblot analysis in select equine populations. for comparison, a naturally infected neospora hughesi horse and an experimentally inoculated neospora caninum horse were used. in addition, all samples were tested for antibodies to sarcocystis neurona by immunoblot analysis. a total of 208 samples was evaluated. the equine populations were derived from five distinct geogra ... | 2001 | 11223207 |
| prevalence of sarcocystis neurona sporocysts in opossums (didelphis virginiana) from rural mississippi. | sarcocystis species sporocysts were found in intestinal scrapings from 24 of 72 opossums (didelphis virginiana) from rural mississippi. the number of sporocysts in each opossum varied from a few ( < 100000) to 187 million. sporocysts from 24 opossums were bioassayed for sarcocystis neurona infections by feeding to gamma-interferon knockout (ko) mice. s. neurona was detected in the brains of ko mice fed sporocysts from 19 opossums by immunohistochemical staining with anti-s. neurona specific poly ... | 2001 | 11223208 |
| sporocyst size of isolates of sarcocystis shed by the virginia opossum (didelphis virginiana). | the virginia opossum (didelphis virginiana) is a definitive host for multiple sarcocystis species including sarcocystis neurona, one of the causative agents of equine protozoal myeloencephalitis (epm), a severe, neuromuscular disease of horses. size and morphologic characteristics of isolates of sarcocystis shed by the opossum were examined to determine if differences were useful in discriminating between the isolates and/or species. collections of sporocysts from 17 opossums were molecularly ch ... | 2001 | 11223210 |
| the south american opossum, didelphis marsupialis, from brazil as another definitive host for sarcocystis speeri dubey and lindsay, 1999. | the north american opossum, didelphis virginiana, is a definitive host for at least 3 species of sarcocvstis: s. falcatula stiles 1983, s. neurona dubey, davis, speer, bowman, de lahunta, granstrom, topper, hamir, cummings, suter 1991, and s. speeri dubey and lindsay 1999. in order to identify species of sarcocystis in the south american opossum, d. inarsupialis, sarcocystis sporocysts from the intestines of a naturally infected opossum (d. marsupialis) from brazil were fed to 4 gamma-interferon ... | 2000 | 11155929 |
| completion of the life cycle of sarcocystis neurona. | sarcocystis neurona is the most important cause of a neurologic disease in horses, equine protozoal myeloencephalitis (epm). the complete life cycle of s. neurona, including the description of sarcocysts and intermediate hosts, has not been completed until now. opossums (didelphis spp.) are definitive hosts, and horses and other mammals are aberrant hosts. in the present study, laboratory-raised domestic cats (felis domesticus) were fed sporocysts from the intestine of a naturally infected oposs ... | 2000 | 11191904 |
| host utilization and seasonal occurrence of dermacentor species (acari:ixodidae) in missouri, usa. | a total of 3,235 dermacentor variabilis (say) specimens were collected from birds, mammals, and by dragging vegetation, and 2,683 d. albipictus (packard) ticks were collected from deer from 1993 to 1996. peak seasonal occurrence of adult d. variabilis was from may through july with a precipitous decrease in august. nymphal d. variabilis populations peaked in june. peak activity of larvae was bimodal, with one activity peak during late summer (september) and a second peak in winter or early sprin ... | 2000 | 11201355 |
| isolation of sarcocystis speeri dubey and lindsay, 1999 parasite from the south american opossum (didelphis albiventris) from argentina. | sarcocystis sporocysts from the intestines of 2 opossums (didelphis albiventris) from argentina were fed to gamma-interferon knockout (ko) and nude mice. protozoal schizonts were seen in brain, liver, spleen, and adrenal glands of mice examined 33-64 days after feeding sporocysts. sarcocysts were seen in skeletal muscles of ko mice 34-71 days after feeding sporocysts. schizonts and sarcocysts were structurally similar to sarcocystis speeri dubey and lindsay, 1999 seen in mice fed sporocysts from ... | 2000 | 10701583 |
| streptococcus didelphis sp. nov., a streptococcus with marked catalase activity isolated from opossums (didelphis virginiana) with suppurative dermatitis and liver fibrosis. | beta-haemolytic, catalase-positive, gram-positive cocci that formed chains in broth media but did not react with lancefield group antisera were isolated from skin lesions, spleen, liver and lungs of nine opossums, including eight from a research colony and one from a wildlife rehabilitation organization. the isolates had vigorous catalase activity that was retained on initial passage on non-blood-containing media, but this activity was lost in subsequent passages. the use of standard phenotypic ... | 2000 | 10758886 |
| experimental transmission of sarcocystis speeri dubey and lindsay, 1999 from the south american opossum (didelphis albiventris) to the north american opossum (didelphis virginiana). | sarcocystis speeri dubey and lindsay, 1999 from the south american opossum didelphis albiventris was successfully transmitted to the north american opossum didelphis virginiana. sporocysts from a naturally infected d. albiventris from argentina were fed to 2 gamma-interferon knockout (ko) mice. the mice were killed 64 and 71 days after sporocyst feeding (daf). muscles containing sarcocysts from the ko mouse killed 71 daf were fed to a captive d. virginiana; this opossum shed sporocysts 11 days a ... | 2000 | 10864267 |
| why fuse the mandibular symphysis? a comparative analysis. | fused symphyses, which evolved independently in several mammalian taxa, including anthropoids, are stiffer and stronger than unfused symphyses. this paper tests the hypothesis that orientations of tooth movements during occlusion are the primary basis for variations in symphyseal fusion. mammals whose teeth have primarily dorsally oriented occlusal trajectories and/or rotate their mandibles during occlusion will not benefit from symphyseal fusion because it prevents independent mandibular moveme ... | 2000 | 10918127 |
| light and electron microscopic features of eperythrozoon-like parasites in a north american opossum (didelphis virginiana). | epierythrocytic parasites associated with a severe anemic episode have not been previously reported in the opossum. a wright-giemsa-stained peripheral blood smear from an anemic north american opossum (didelphis virginiana) revealed numerous organisms attached to red blood cells either singularly or in chains. ring forms of the organism were common and could be found free in the plasma. electron microscopy revealed that these organisms were attached to the intact plasma membrane in depressions o ... | 2000 | 10982141 |
| a staging scheme for assessing development in vitro of organogenesis stage embryos of the stripe-faced dunnart, sminthopsis macroura (marsupialia: dasyuridae). | the inaccessibility of mammalian organogenesis stage embryos has precluded their widespread use in embryological and teratological studies. as organogenesis occurs during the last 1.5 days of the 10. 7 days of gestation in the stripe-faced dunnart (sminthopsis macroura), the aim of the present study was to investigate whether day 9 and day 10 embryos and fetuses could be grown to term in vitro. high glucose dulbecco's modified eagle's medium with 10% fetal calf serum (fcs) supported embryonic gr ... | 2000 | 11006151 |
| prevalence of sarcocystis species sporocysts in wild-caught opossums (didelphis virginiana). | sarcocystis sporocysts were found in intestinal scrapings from 24 (54.5%) of 44 opossums (didelphis virginiana). the number of sporocysts varied from a few (< 10,000) to 245 million. sporocysts from 23 of 24 opossums were fed to captive budgerigars (melopsittacus undulatas), and the inocula from 21 opossums were infective, indicating the presence of sarcocystis falcatula. sporocysts from 24 opossums were fed to gamma-interferon-knockout (ko) or nude mice; inocula from 14 opossums were infective ... | 2000 | 10958444 |
| isolation and characterization of dm40 and dm43, two snake venom metalloproteinase inhibitors from didelphis marsupialis serum. | from didelphis marsupialis serum, two antihemorrhagic proteins were isolated by deae-sephacel, phenyl-sepharose and superdex 200 and characterized. their masses by mass spectrometry were 40318 amu for dm40 and 42373 and 43010 amu for dm43, indicating the presence of isoforms for the last. molecular masses of 44.8 and 47.3 were obtained by sds-page, respectively for dm40 and dm43. both inhibitors showed isoelectric points lower than 3.5 and glycosylation percentages varying from 20.5 to 29.0%, as ... | 2000 | 10779682 |
| repair of the transected spinal cord at different stages of development in the north american opossum, didelphis virginiana. | when the thoracic spinal cord is transected on postnatal day (pd) 5 in the north american opossum, descending and ascending axons grow through the lesion site. when the lesion is made on pd20, comparable growth is limited to a subset of descending axons. to better understand the mechanisms underlying these differences, we analyzed the transection site at different times after lesioning at both ages. axons which crossed the lesion site could be identified using silver impregnation and immunostain ... | 2000 | 11179852 |
| regeneration of descending spinal axons after transection of the thoracic spinal cord during early development in the north american opossum, didelphis virginiana. | opossums are born in an immature, fetal-like state, making it possible to lesion their spinal cord early in development without intrauterine surgery. when the thoracic spinal cord of the north american opossum, didelphis virginiana, is transected on postnatal day 5, and injections of fast blue (fb) are made caudal to the lesion site 30-40 days or 6 months later, neurons are labeled in all of the spinal and supraspinal areas that are labeled after comparable injections in age-matched, unlesioned ... | 2000 | 11165803 |
| granulomatous pneumonia in the opossum (didelphis virginiana) associated with an intracellular fungal agent. | two of nine female opossums (didelphis virginiana) in a closed breeding colony were submitted for necropsy due to a history of poor reproductive performance in the absence of overt clinical disease. on histologic examination, marked granulomatous to pyogranulomatous pneumonia was identified in these animals. | 2000 | 10894501 |
| energy metabolism of the virginia opossum during fasting and exercise. | rates of oxygen consumption and co(2) production were measured in virginia opossums (didelphis virginiana) during fasting and prolonged exercise to quantify changes in total energy expenditure and oxidative fuel selection. we hypothesized that fasting would cause metabolic depression and a progressive shift towards lipid utilization to spare alternative substrates. it was also predicted that prolonged exercise would cause the same relative changes in fuel preference as fasting, but on a compress ... | 2000 | 10729284 |
| rescue of axotomized rubrospinal neurons by brain-derived neurotrophic factor (bdnf) in the developing opossum, didelphis virginiana. | many rubrospinal neurons die in developing opossums when their axon is cut at thoracic levels of the spinal cord and in the present study we asked whether they can be rescued by brain-derived neurotrophic factor (bdnf). bilateral injections of fast blue (fb) were made into the rostral lumbar cord to prelabel rubrospinal neurons and 5 days later the rubrospinal tract was cut unilaterally by hemisecting the thoracic cord. immediately after hemisection, bdnf-soaked gelfoam was placed into the lesio ... | 1999 | 10611517 |
| screening for fibrinolytic activity in eight viperid venoms. | snake venoms contain direct-acting fibrinolytic metalloproteinases (mmp) that could have important applications in medicine. fibrinolytic enzymes isolated from venom can induce in vitro clot lysis by directly acting on a fibrin clot. the most ideal fibrinolytic enzyme would have high affinity for clots, dissolve clots directly without causing hemorrhage, and would not be neutralized in vivo by endogenous metalloproteinase inhibitors. the purpose of this study was to compare deae/hplc venom profi ... | 1999 | 10579653 |
| characterization of metastatic intestinal adenocarcinoma with differentiation into multiple morphologic cell types in a virginia opossum. | a captively maintained mature male opossum (didelphis virginiana) utilized in a research protocol was presented with clinical signs of chronic diarrhea and severe muscle wasting. at necropsy, there was multifocal mural gastric, intestinal, and urinary bladder thickening, concurrent bilateral hydroureter and hydronephrosis, and extensive fibrous abdominal adhesions. histologic evaluation revealed intestinal adenocarcinoma with coelomic metastasis to the stomach and urinary bladder. the adenocarci ... | 1999 | 10490217 |
| field immobilization and euthanasia of american opossum. | seventeen recently trapped opossum, didelphis virginiana, (median weight 2.45 kg; range = 1.6-5.0 kg; quartiles = 1.8-3.3 kg) were immobilized with either telazol (15 or 30 mg/kg) or a mixture of medetomidine (100 micrograms/kg), butorphanol (0.2 mg/kg), and ketamine hcl (10 mg/kg) based on estimated weights. anesthetized animals were subjected to cardiac puncture for blood withdrawal and toe pinch. euthanasia was accomplished by intracardiac administration of 1 ml of concentrated pentobarbital ... | 1999 | 10073367 |
| developmental plasticity of ascending spinal axons studies using the north american opossum, didelphis virginiana. | the objectives of the present study were to determine if axons of all ascending tracts grow through the lesion after transection of the thoracic spinal cord during development in the north american opossum, and if so, whether they reach regions of the brain they normally innervate. opossum pups were subjected to transection of the mid-thoracic cord at pd5, pd8, pd12, pd20, or pd26 and injections of fast blue (fb) into the lower thoracic or upper lumbar cord 30-40 days or 6 months later. in the p ... | 1999 | 9974160 |
| site selection by intestinal helminths of the virginia opossum (didelphis virginiana). | digestive tract helminths of the virginia opossum (didelphis virginiana) were examined for site specificity and interspecific interactions. thirty opossums were live-trapped at 2 localities in georgia, killed, and their digestive tracts removed and divided into the following sections; esophagus, stomach, small intestine (20 equal sections), cecum, and large intestine (5 equal sections). helminths present in each section were identified and counted. three trematode, 1 cestode, 2 acanthocephala, a ... | 1999 | 10207354 |
| multiple dna markers differentiate sarcocystis neurona and sarcocystis falcatula. | studies designed to investigate the causative agent of equine protozoal myeloencephalitis and its life cycle have been hampered by the marked similarity of sarcocystis neurona to other sarcocystis spp. present in the same definitive host. random-amplified polymorphic dna techniques were used to amplify dna from isolates of s. neurona and sarcocystis falcatula. dna sequence analysis of polymerase chain reaction (pcr) products was then used to design pcr primers to amplify specific sarcocystis spp ... | 1999 | 10219299 |
| are sarcocystis neurona and sarcocystis falcatula synonymous? a horse infection challenge. | equine protozoal myeloencephalitis (epm) is a debilitating neurologic disease of the horse. the causative agent. sarcocystis neurona, has been suggested to be synonymous with sarcocystis falcatula, implying a role for birds as intermediate hosts. to test this hypothesis, opossums (didelphis virginiana) were fed muscles containing s. falcatula sarcocysts from naturally infected brown-headed cowbirds (molothrus ater). ten horses were tested extensively to ensure no previous exposure to s. neurona ... | 1999 | 10219313 |
| patterns of infestation by adult dermacentor variabilis (acari: ixodidae) in a mark-recapture study of raccoons (mammalia: carnivora) and virginia opossums (mammalia: didelphimorphia) in tennessee. | a mark-recapture study of raccoons (procyon lotor l.) and virginia opossums (didelphis virginiana kerr) was conducted from february 1991 through april 1994 to determine host interactions with adult dermacentor variabilis say. we captured 1,293 raccoons and virginia opossums during the 3-yr study (140 individual raccoons and 160 individual virginia opossums) with 1,895 adult d. variabilis collected. raccoons had a significantly higher mean intensity and higher prevalence of adult ticks than virgi ... | 1999 | 10337094 |
| implications of raccoon latrines in the epizootiology of baylisascariasis. | raccoons (procyon lotor) frequently establish defecation sites, termed latrines, on large logs, stumps, rocks, and other horizontally oriented structures/surfaces. these latrines are important foci of infective eggs of baylisascaris procyonis, a nematode parasite of raccoons which is pathogenic to numerous species of mammals and birds. to examine the role of raccoon latrines in this animal-parasite interaction, we documented animal visitations to raccoon latrines in two large forested tracts and ... | 1999 | 10479081 |
| subretinal macrophages in the developing eye of eutherian mammals and marsupials. | blood-borne mononuclear cells invade the developing retina via the hyaloid vasculature at the optic nerve head. following removal of apoptotic cell debris they give rise to the network of resident microglia. the population of cells recently described in the peripheral subretinal space of developing human eyes may represent a further population of macrophages destined to become microglia. the aim of the present study was to confirm the presence of subretinal macrophages in the developing eye in o ... | 1999 | 10526023 |
| ticks and antibodies to borrelia burgdorferi from mammals at cape hatteras, nc and assateague island, md and va. | results of a survey for ixodid ticks and/or serum antibodies to borrelia burgdorferi from 14 species of small to large mammals from eastern coastal areas of the united states are presented. most samples were obtained from july 1987 through june 1989 (excluding december-march) at 3 locales: assateague is. national seashore, worcester co., md., and accomack co., va. (approximately 38 degrees 05' n 75 degrees 10' w), and cape hatteras national seashore, dare co., nc (approximately 35 degrees 30' n ... | 1999 | 10534951 |
| oral rabies vaccine contact by raccoons and nontarget species in a field trial in florida. | rabies is enzootic in raccoons (procyon lotor) in the eastern united states. oral vaccination of free-ranging raccoons against rabies has the potential to control the disease in a principal reservoir and reduce the risk of rabies exposure among domestic animals and humans. free-ranging animal contact with baits containing a vaccinia virus recombinant vaccine expressing the rabies glycoprotein gene (v-rg) was monitored in pinellas county (florida, usa) from february through may 1997. bait contact ... | 1999 | 10574527 |
| sarcocystis speeri n. sp. (protozoa: sarcocystidae) from the opossum (didelphis virginiana). | the north american opossum (didelphis virginiana) is host to at least 3 species of sarcocystis: sarcocystisfalcatula, sarcocystis neurona, and a recently recognized sarcocystis sp. a new name, sarcocystis speeri, is proposed for the third unnamed sarcocystis. immunodeficient mice are an experimental intermediate host for s. speeri. sarcocystis speeri sporocysts are 12-15 x 8-10 microm in size, and its schizonts are found in many organs of mice. sarcocysts of s. speeri are found in skeletal muscl ... | 1999 | 10577729 |
| postnatal changes in blood respiratory characteristics in an american opossum (didelphis virginiana). | the oxygen affinity of opossum blood changes in the postnatal period. the youngest opossums studied were 53 days of age (dated from the day of transit from vagina to pouch) and still confined to the maternal pouch: they had a blood p50 of 32.6 +/- 2.9 mm hg. the blood p50 value then increased significantly, in two steps. first, while the young were still in the pouch, blood p50 rose secondary to a rise in the concentration of 2,3-diphosphoglycerate (dpg). blood p50 and dpg concentration then rem ... | 1999 | 15307 |
| development of epiphyseal structure and function in didelphis virginiana (marsupiala, didelphidae). | this study addressed the question of how the epiphyses of growing mammals change their external shape and internal architecture during postnatal development. ontogenetic transformations in the external form and internal structure of the fore- and hindlimb epiphyses were examined in a mixed cross-sectional sample of didelphis virginiana using two methods: morphometric analysis of linear epiphyseal dimensions and histological staining of serially sectioned epiphyses. metric data indicate that virg ... | 1999 | 29847889 |
| the electrocardiogram of the virginia opossum (didelphis virginiana). | 1998 | 106584 | |
| mycobacterium bovis in coyotes from michigan. | during a survey for tuberculosis in wild carnivores and omnivores, mycobacterium bovis was cultured from pooled lymph nodes of three adult female coyotes (canis latrans) harvested by hunters in michigan (usa). no gross or histologic lesions suggestive of tuberculosis were seen in these animals. one coyote was taken from montmorency county and two coyotes from alcona county located in the north-eastern portion of michigan's lower peninsula where free-ranging white-tailed deer (odocoileus virginia ... | 1998 | 9706576 |
| the detection of hemorrhagic proteins in snake venoms using monoclonal antibodies against virginia opossum (didelphis virginiana) serum. | most snakes and a few warm-blooded animals have a resistance to snake venoms because of naturally occurring antihemorrhagins found in their sera. the antihemorrhagins in serum of virginia opossum (didelphis virginiana) neutralize hemorrhagic activity by binding to hemorrhagins in snake venoms. the binding characteristic of antihemorrhagins in d. virginiana serum was used to develop a five-step western blot. the detection of hemorrhagic proteins were measured indirectly with antihemorrhagins in v ... | 1998 | 9723843 |
| seroprevalence of antibodies against toxoplasma gondii in free-ranging mammals in iowa. | serum samples from raccoons (procyon lotor), striped skunks (mephitis mephitis), virginia opossums (didelphis virginiana), and free-ranging house cats trapped in iowa between 1984 and 1988 were tested for antibodies against toxoplasma gondii using the modified direct agglutination test (mat). antibody titers > or = 1:32 were considered indicative of infection. prevalence rates by species were estimated for raccoons at 134/885 (15%), skunks at 38/81 (47%), opossums at 12/53 (23%), and cats at 16/ ... | 1998 | 9813854 |
| isolation of a third species of sarcocystis in immunodeficient mice fed feces from opossums (didelphis virginiana) and its differentiation from sarcocystis falcatula and sarcocystis neurona. | opossums (didelphis virginiana) were found to be hosts for 3 species of sarcocystis: sarcocystis falcatula with an avian intermediate host, s. neurona with an undetermined intermediate host, and a third, unnamed, species. sporocysts from the intestines of 2 opossums (nos. 26 and 47) were fed to budgerigars (melopsittacus undulatus), nude mice, and gamma-interferon knockout (ko) mice. sporocysts of s. falcatula were not infective to nude or ko mice. sporocysts of s. neurona induced encephalitis i ... | 1998 | 9920306 |
| isolation in immunodeficient mice of sarcocystis neurona from opossum (didelphis virginiana) faeces, and its differentiation from sarcocystis falcatula. | sarcocystis neurona was isolated in nude mice and gamma-interferon knockout mice fed sporocysts from faeces of naturally infected opossums (didelphis virginiana). mice fed sporocysts became lethargic and developed encephalitis. protozoa were first found in the brain starting 21 days post-inoculation. sarcocystis neurona was recovered in cell culture from the homogenate of liver, spleen and brain of a nude mouse 11 days after feeding sporocysts. the protozoa in mouse brain and in cell culture mul ... | 1998 | 9925260 |
| a review of histogenesis/organogenesis in the developing north american opossum (didelphis virginiana). | 1998 | 9816726 | |
| a review of histogenesis/organogenesis in the developing north american opossum (didelphis virginiana). | 1998 | 9816723 | |
| snake envenomation and protective natural endogenous proteins: a mini review of the recent developments (1991-1997). | the properties of several factors--antihaemorrhagic, antineurotoxic, antimyotoxic--isolated from the blood serum or plasma of different animals are described with more emphasis placed on the structural differences and similarities among the factors of the snake (trimeresurus flavoviridis) and mammals (didelphis marsupials and herpestes edwardsii). classification of antihaemorrhagic factors of snake and mammals according to structural homologies, and their effectiveness in neutralizing venom haem ... | 1998 | 9792161 |
| origin, course, and laterality of spinocerebellar axons in the north american opossum, didelphis virginiana. | spinocerebellar axons have been studied extensively in placental mammals, but there have been no full reports on their origin, laterality, or spinal course in any marsupial. we have used the north american opossum (didelphis virginiana) to obtain such information and to ask whether any spinocerebellar neurons innervate both the anterior and posterior lobes of the cerebellum through axonal collaterals. to identify spinal neurons that project to the cerebellum, we employed the retrograde transport ... | 1998 | 9713988 |
| regeneration of supraspinal axons after transection of the thoracic spinal cord in the developing opossum, didelphis virginiana. | when the thoracic spinal cord of the north american opossum is transected early in development, supraspinal axons grow through the lesion. in the experiments reported here, we asked whether regeneration of cut axons contributes to such growth. fast blue (fb) was injected into the lumbar cord on postnatal day (pd)5, 8, 15, or 20. five days later, fb was removed by gentle suction, and the spinal cord was transected at thoracic levels. fourteen days later, rhodamine b dextran was injected between t ... | 1998 | 9703028 |
| adult opossums (didelphis virginiana) demonstrate near normal locomotion after spinal cord transection as neonates. | when the thoracic spinal cord of the north american opossum (didelphis virginiana) is transected on postnatal day (pd) 5, the site of injury becomes bridged by histologically recognizable spinal cord and axons which form major long tracts grow through the lesion. in the present study we asked whether opossums lesioned on pd5 have normal use of the hindlimbs as adults and, if so, whether that use is dependent upon axons which grow through the lesion site. the thoracic spinal cord was transected o ... | 1998 | 9582254 |
| north american opossum didelphis virginiana as a fetal nephrotoxicity model: histologic and ultrastructural assessment of uranyl nitrate (un)-induced damage. | we have used our opossum model of fetal nephrotoxicity to investigate uranyl nitrate-induced morphologic changes in the developing kidney. the present study establishes a renal dose response curve for the uranyl nitrate (un). we find that pups treated with nonlethal doses of un do not demonstrate growth retardation compared to saline-treated controls. the kidneys of un-treated pups are heavier than the control animals, an effect less apparent the longer the pups are followed. a low dose of 60 mg ... | 1997 | 9372500 |
| glucose kinetics of the virginia opossum: possible implications for predicting glucose turnover in mammals. | primed continuous infusions of 6-3h-glucose, respirometry and measurements of nitrogen excretion were carried out in adult virginia opossums (didelphis virginiana). our goals were to determine resting glucose turnover rate, to establish the relative importance of this oxidative fuel in the energy budget of this species, to assess whether metabolic rate is a better predictor of glucose turnover rate than body mass and to demonstrate that glucose kinetics can be measured in the opossum for future ... | 1997 | 9406445 |
| developmental plasticity of selected spinocerebellar axons. studies using the north american opossum, didelphis virginiana. | when the thoracic spinal cord of the opossum is hemisected at postnatal day 5 or 8, but not at day 12 or later ages, spinocerebellar axons which originate from spinal border cells, the sacral/coccygeal ventrolateral nucleus, and stilling's nucleus grow through the lesion and reach the cerebellum. the critical period for such growth is comparable to that reported previously for spinocerebellar axons originating within clarke's nucleus and for axons of the fasciculus gracilis, but shorter than tha ... | 1997 | 9352116 |
| l-arginine deficiency causes suppression of nonadrenergic noncholinergic nerve-mediated smooth muscle relaxation: role of l-citrulline recycling. | studies were performed on the internal anal sphincter (ias) smooth muscle strips obtained from opossums (didelphis virginiana). isometric tension and l-arginine levels of the tissues were measured under basal conditions, in the presence of electrical field stimulation (efs) and after treatment with different concentrations of arginase. for the nonadrenergic noncholinergic nerve stimulation, short trains (4 sec) as well as continuous efs were used. during continuous efs, after the initial ias rel ... | 1997 | 9223577 |
| didelphid behavior. | there are approximately 75 species of american opossums (didelphids). systematic behavioral research has been reported for only a small number of species, namely, monodelphis domestica and didelphis virginiana. observational studies and field reports on several other didelphid species have also been published. the current review covers behavioral studies on didelphids including research on territoriality, reproductive behaviors, parturition, maternal behaviors, nest-building, vocalizations, scen ... | 1997 | 9168270 |
| ontogeny and limb bone scaling in two new world marsupials, monodelphis domestica and didelphis virginiana. | this study examines the growth of two species of marsupials who share common ancestry and are born at the same neonatal size of a little less than 1 g. despite this similarity at birth, adult size of these two species differs by about 50 times, with the smaller species believed to be the more ancestral. we quantified the growth in the limb bones (humerus, femur, ulna, tibia, metacarpal, and metatarsal) beginning around 40 days of age until adult size was reached. results indicate that the larger ... | 1997 | 8989872 |
| early development and developmental plasticity of the fasciculus gracilis in the north american opossum (didelphis virginiana). | the first objective of the present study was to ask when axons of the fasciculus gracilis reach the nucleus gracilis in the north american opossum (didelphis virginiana). when fast blue (fb) was injected into the lumbar cord on postnatal day (pd) 1 and the pups were killed 2 days later, labeled axons were present within a distinct fasciculus gracilis at thoracic and cervical levels of the cord. when comparable injections were made at pd3 or 5 and the pups were allowed to survive for the same tim ... | 1997 | 9051256 |
| experimental induction of equine protozoal myeloencephalitis in horses using sarcocystis sp. sporocysts from the opossum (didelphis virginiana). | sarcocystis sp. sporocysts isolated from eight feral opossums (didelphis virginiana) were pooled and fed to 18 commercially reared budgerigars (melopsittacus undulatus), 14 wild-caught sparrows (passer domesticus), one wild-caught slate-colored junco (junco hyemalis) and five weanling horses (equus caballus). all budgerigars died within 5 weeks post inoculation (wpi). histologic examination revealed meronts within the pulmonary epithelia and typical sarcocystis falcatula sarcocysts developing in ... | 1997 | 9066066 |
| development of the lymphoid tissues of the tammar wallaby macropus eugenii. | a study has been made of the development of four lymphoid tissues from birth to maturity in the tammar wallaby macropus eugenii--the cervical and thoracic thymus, lymph nodes and gut-associated lymphoid tissue (galt). the development of these tissues in the tammar wallaby is similar to that in two other marsupials, the quokka setonix brachyurus and the virginian opossum didelphis virginiana. lymphocytes were first detected in the cervical thymus of the tammar at day 2 post partum and in the thor ... | 1997 | 9208435 |
| 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 |
| morphological observations on the mesonephros in the postnatal opossum, didelphis virginiana. | the mesonephros of the opossum persists for 3-4 weeks into the postnatal period. based on our observations of its structure, and the vital dye experiments of others, it appears that the opossum mesonephros is functional during the first 10 days of the postnatal period. the mesonephros of the newborn opossum consists of 35-45 nephron units which are structurally very similar to metanephric nephrons except that they lack a loop of henle. by the end of the first postnatal week, regression which pro ... | 1996 | 500493 |
| ticks (acari: ixodidae) in bulloch county, georgia. | an 18-mo study was conducted in bulloch county, georgia, to determine tick species composition, seasonal activity of individual tick species, and host-tick associations. the following 7 methods of tick collection were included: (1) live trapping of potential host animals, (2) checking wild game, (3) drag sampling, (4) carbon dioxide attraction, (5) checking livestock, road kills, nests, and burrows, (6) samples submitted from veterinarians, and (7) ticks collected by local residents and submitte ... | 1996 | 8742526 |
| a molecular and evolutionary study of the beta-globin gene family of the australian marsupial sminthopsis crassicaudata. | beta-globin gene families in eutherians (placental mammals) consist of a set of four or more developmentally regulated genes which are closely linked and, in general, arranged in the order 5'-embryonic/fetal genes-adult genes-3'. this cluster of genes is proposed to have arisen by tandem duplication of ancestral beta-globin genes, with the first duplication occurring 200 to 155 mybp just prior to a period in mammalian evolution when eutherians and marsupials diverged from a common ancestor. in t ... | 1996 | 8752008 |
| ontogeny of suckling mechanisms in opossums (didelphis virginiana). | although adult mammals have several different mechanisms for drinking liquids, relatively little is known about the variation in mechanisms used by infants for suckling and how the mechanics of suckling change as a function of ontogeny. we examined suckling in infant opossums, animals that as adults use a lapping mechanism to drink. the youngest infants (45 days old) used a suction, pumping mechanism, based on dorsal/ventral tongue movements, similar to what has been documented in infant primate ... | 1996 | 8872320 |
| evidence for growth of supraspinal axons through the lesion after transection of the thoracic spinal cord in the developing opossum didelphis virginiana. | in the present study, we asked whether supraspinal axons grow through a complete transection of the spinal cord in the developing opossum didelphis virginiana. when the thoracic cord was transected at postnatal day (pd) 5 and bilateral injections of fast blue (fb) were made four segments caudal to the lesion 30-40 days later, fb-containing neurons were found in each of the supraspinal nuclei labeled by comparable injections in age-matched unlesioned controls. continuity between the cut ends of t ... | 1996 | 8835721 |
| growth of dorsal spinocerebellar axons through a lesion of their spinal pathway during early development in the north american opossum, didelphis virginiana. | supraspinal axons grow around or through lesions of their spinal pathway during specific critical periods of mammalian development, but comparable plasticity has not been documented for axons which form ascending tracts. in the present study, we asked whether axons of the dorsal spinocerebellar tract (dsct) are capable of such growth. the spinal cord of the north american opossum, didelphis virginiana, was hemisected at mid-thoracic levels between postnatal day (pd) 5 and 68 and after varying su ... | 1996 | 8804690 |
| milk composition in the north american opossum (didelphis virginiana). | the composition of milk samples collected from captive opossums (didelphis virginiana) was determined at various intervals during lactation. the milk solids increased from 9% at week one to a maximum of 34% at 11 weeks post-partum. there were changes in the relative proportions of protein, lipid and carbohydrate at different stages of lactation. lipid represented the greatest fraction of the solids except for a period at mid-lactation when there was a peak in protein concentration. the concentra ... | 1996 | 8829811 |
| evidence for gap-43 within descending spinal axons in the north american opossum, didelphis virginiana. | we have shown previously that gap-43, a growth associated protein characteristically present in growing and regenerating axons, is relatively abundant in the spinal cord of adult opossums. in the present study, we combined the orthograde transport of the fluorescent marker fluoro-ruby with immunofluorescence for gap-43 to determine if any of it is present within descending spinal axons. when fluoro-ruby was injected into the red nucleus and midbrain tegmentum, the medial pontine or medullary ret ... | 1996 | 9156783 |
| auditory quality cues are more effective than auditory location cues in a r--no r (go--no go) differentiation: the extension of the rule to primitive mammals (american opossum, didelphis virginiana). | discrimination learning of instrumental responses to auditory compound stimuli was investigated in opossums using the r-no r (go-no go) differentiation. each compound stimulus consisted of two factors: quality and location. each correct response performed to the conditioned positive, or "safe" stimulus, was rewarded by food and never punished. each incorrect response performed to the conditioned negative, or "warning" stimulus, was punished by an electric shock. in subsequent testing, each oposs ... | 1996 | 9033130 |