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Of 15 D. The isolates were biologically and biochemically indistinguishable from one isolate of L. Two of eight D. Five of nine specimens of Proechimys guyannensis, from the vicinity of Manaus, were also infected with L. A further 13 mammals eight species were negative for Leishmania. The importance of opossums as a reservoir of L.

Although they may play only a minor role in virgin forest which is undisturbed by man, opossums D. Common opossum Didelphis marsupialis Linnaeus, : food and medicine for people in the Amazon. In the Amazon rainforest, biodiversity is a significant resource for traditional communities, as it can be used as a relevant source of protein and it has a promising zootherapeutic potential. Studies on knowledge and ways how local peoples use the fauna are still incipient. This paper presents both the knowledge on and food and medicinal uses of common opossum Didelphis marsupialis by riverine communities in an Amazon floodplain region.

The main methods used were structured and semi-structured interviews, the "snowball" technique, and participant observation. The study showed that D. Its meat is prized by inhabitants as it is classified as tasty, soft and, in some cases, it is designated as the best bushmeat in the region. The interviewees have demonstrated a thorough knowledge on various aspects of the animal's biology, such as its diet, behavior, and places of occurrence.

The hunting activity is practiced by men, but the preparation of meat and medicinal oil are tasks mainly performed by women.

In medical terms, common opossum is used in the treatment of various diseases, such as rheumatism, asthma, sore throat, and inflammation. Its fat is used as a traditional medicine and it is indicated for many types of diseases. Although the species concerned is treated with hostility in various Brazilian regions, in the case of Abaetetuba this animal is strongly prized due to the good quality of its meat.

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However, despite the value assigned to the species, its consumption should be the subject of further. Trypanosoma cruzi in the opossum Didelphis marsupialis: an indirect fluorescent antibody test for the diagnosis and follow-up of natural and experimental infections. The use of an indirect fluorescent antibody test IFAT performed in a "sandwich" technique has demonstrated: i the usefulness of the test for the diagnosis of Trypanosoma cruzi infection in the opossum Didelphis marsupialis; ii the existence of differences in the serological response of the opossum , that were related to the parasite strain and were clearly evident during the follow-up of experimental infections in laboratory born specimens; iii that, despite a good correlation between serological and parasitological examinations, IFAT was the most sensitive diagnostic test used, followed by xenodiagnosis; and, iv that in general, the opossum D.

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.

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Using the amplified sequences as probes, several protamine cDNA clones were isolated. The protein sequence, predicted from the cDNA sequences, consisted of 57 amino acids, contained a large number of arginine residues and exhibited the sequence ARYR at its amino terminus, which is conserved in avian and most eutherian mammal protamines. Like the true protamines of trout and chicken, the opossum protamine lacked cysteine residues, distinguishing it from placental mammalian protamine 1 P1 or stable protamines. Examination of the protamine gene, isolated by polymerase-chain-reaction amplification of genomic DNA, revealed the presence of an intron dividing the protamine-coding region, a common characteristic of all mammalian P1 genes.

In addition, extensive sequence identity in the 5' and 3' flanking regions between mouse and opossum sequences classify the marsupial protamine as being closely related to placental mammal P1. Protamine transcripts, in both birds and mammals, are present in two size classes, differing by the length of their poly A tails either short or long. Examination of opossum protamine transcripts by Northern hybridization revealed four distinct mRNA species in the total RNA fraction, two of which were enriched in the poly A -rich fraction.

Northern-blot analysis, using an intron-specific probe, revealed the presence of intron sequences in two of the four protamine transcripts. If expressed, the corresponding protein from intron-containing transcripts would differ from spliced transcripts by length 49 versus 57 amino. The current work describes K. The sporocysts recovered from urine samples were ellipsoidal, Didelphis marsupialis should not have transmitted K. Therefore, D. Trypanosoma cruzi in the opossum Didelphis marsupialis: parasitological and serological follow-up of the acute infection. The opossum Didelphis marsupialis is known to be among the most important wild reservoirs of Trypanosoma cruzi and one in which the trypanosome may go through both the usual vertebrate intracellular cycle in its tissues and an extracellular cycle in the lumen of its scent glands.

The species is highly resistant to heavy inocula and, depending on the parasite strain, experimental infections may be permanent or self limited. Aiming to understand the mechanisms involved in this parasite-host interaction we made a study of the acute phase of infection with different T. Strains F, G and G produced durable infections with relatively high parasitemia and invasion of the scent glands, while equivalent inocula of the Y strain resulted in scanty parasitemia of short duration, no invasion of the SG, and no evidence of persistent parasitism.

A smaller inoculum of G produced only subpatent though persistent parasitemia and no invasion of the scent glands. The humoral immune response was less marked in the Y group; among the other groups IgM and IgG antibodies increased to high levels, higher in the G group. The increase in IgG coincided with a drop of parasitemia to subpatent levels.

Two opossums inoculated directly in the scent glands with culture forms of the Y strain had a short-lived subpatent parasitemia, but the parasites remained in the glands and serum Ig antibodies reached high levels. Immunoblot analysis showed that the sera of the inoculated opossums recognized few T.

However, with the only exception of those subcutaneously inoculated with the Y strain and including two naturally infected specimens, all the opossum 's sera recognized a kDa peptide in all T. Our results confirm that opossums are able to selectively eliminate some strains of T. Identification of opossums Didelphis aurita Wied-Neuweid, as a definitive host of Sarcocystis falcatula-like sporocysts.

This study was conducted to identify the Sarcocystis species that infect the opossum Didelphis aurita in order to determine which sporocysts they are excreating in to the environment and help determine the role of D. Sporocysts were obtained from intestinal tracts of 8 of 13 D. All other birds and all mice were euthanized 60 DAI. Schizonts were observed in the lungs using histology and immunostaining in birds examined prior to 60 DAI. Sarcocystis asexual stages were isolated in cell cultures inoculated with sporozoites.

Parasite DNA isolated from bird tissues and cell cultures demonstrated that S. Asexual stages molecularly characterized as S. This study demonstrated that D. If dtli. Serological evidence of exposure to tick-borne agents in opossums Didelphis spp. The presence of antibodies to anti-R. Opossum endpoint titers ranged from 64 to 1, for R. These serological results suggest that opossums have been exposed to Rickettsia spp.

Common opossums Didelphis marsupialis are found throughout the Caribbean island of Trinidad and Tobago. The present work was conducted on 10 skulls and mandibles of the common opossum to describe the osteology and foramina of these skulls and mandibles grossly and radiographically.

The information that is garnered can be used to detect, diagnose, and treat head affections, as well as for comparative studies with the skulls and mandibles of other similar species. The skulls and mandibles were prepared and cleaned using standard method. All of the characteristic features of various standards views of the skulls bones, including dorsal, lateral, caudal and midsagittal, and the lateral and caudal views of the mandibles as well as the foramina of the skulls and mandibles were described and discussed.

Each skull was divided into long facial and short cranial regions. No supraorbital foramen was observed in the skulls. The tympanic bulla was absent while there was the tympanic process of the alisphenoid. The temporal process of the zygomatic bone, zygomatic process of maxilla, and zygomatic process of the squamosal bone formed the zygomatic arch.

The dental formula was confirmed. The bones and foramina of the skull and mandible were similar to other marsupial species and were homologue to that of other mammals. Efferent connections of the olfactory bulb in the opossum Didelphis marsupialis aurita : a Fink-Heimer study. The efferent concentrations of the olfactory bulb OB in the opossum Didelphis marsupialis aurita were studied by the aid of the Fink-Heimer technique.

Development of the Digestive System in the North American Opossum (Didelphis virginiana)

Following lesions restricted to the OB, ipsilateral degenerating fibers entered the lateral olfactory tract and were treated to terminal fields essentially limited to the outer portion of the plexiform layer sublamina IA of the following structures: all the subdivisions of the anterior olfactory nucleus, the rostroventral tenia tecta, the full extent of the olfactory tubercle, the nucleus of the lateral olfactory tract, the anterior portion of the medial amygdaloid nucleus, the whole cortical amygdaloid nucleus in the posteromedial subdivision of this structure the degeneration was very scanty , and the sulcal, piriform, and lateral entorhinal cortices.

Some degree of topographical organization in the OB projections was noticed in the rostral portion of the lateral olfactory tract and within the external and lateral subdivisions of the anterior olfactory nucleus. In another series of experiments, when the lesion also involved the accessory olfactory bulb, heavy terminal degeneration occurred along the whole extent of the medial amygdaloid nucleus and in the posteromedial subdivision of the cortical amygdaloid nucleus. These findings indicate that, although very similar to those described in other mammals, the OB efferent connections in the opossum present some peculiarities; namely, the existence of dense terminal fields in the sulcal cortex and in the rostral district of the medial amygdaloid nucleus.

The endogenous life cycle of Eimeria marmosopos was studied in experimentally infected young opossums , Didelphis marsupialis. All the endogenous stages were located in the epithelial cells of villi in the small intestine. Giemsa-stained mucosal scrapings and histological sections were studied for the diagnosis of all the life cycle stages. Eimeria marmosopos has 3 generations of meronts M that differ by size, shape, and number of merozoites m , which also differ in their size, shape, and location of their nuclei within the cytoplasm of the meronts.

The 3 meront types, M 1 -M 3 , respectively, had m 1 , m 2 , and m 3 merozoites. Macrogametocytes and microgametocytes, as well as macrogametes and microgametes, completed the sexual cycle, finishing with the formation of unsporulated oocysts. This parasite's endogenous development produced severe intestinal lesions in experimentally infected opossums.

There are 56 Eimeria species known from all marsupials worldwide, but this is the first complete life cycle in which both the asexual and sexual stages have been documented. Humoral immune response kinetics in Philander opossum and Didelphis marsupialis infected and immunized by Trypanosoma cruzi employing an immunofluorescence antibody test. Philander opossum and Didelphis marsupialis considered the most ancient mammals and an evolutionary success, maintain parasitism by Trypanosoma cruzi without developing any apparent disease or important tissue lesion.

In order to elucidate this well-balanced interaction, we decided to compare the humoral immune response kinetics of the two didelphids naturally and experimentally infected with T. Both didelphids responded with high serological titers to different immunization routes, while the earliest response occurred with the intradermic route. Serological titers of naturally infected P. The serological titers of the experimentally infected animals varied according to the inoculated strain.

Humberg, Roberta M. We investigated the occurrence of Leishmania infantum chagasi in Didelphis albiventris opossums at a wild animal rehabilitation center in the city of Campo Grande, Brazil. A total of 54 opossums were tested for L. The samples were analyzed by direct examination, culturing in a specific medium, and polymerase chain reaction—restriction fragment length polymorphism.

Leishmania i. A total of These results suggest a role for D. Wheat germ agglutinin conjugated to horseradish peroxidase WGA-HRP was injected unilaterally into the pretectocollicular region of opossums Didelphis marsupialis aurita , primarily to investigate the existence of a commissural subcortical pathway but also to reveal afferents and efferents of the nucleus of the optic tract NOT and dorsal terminal nucleus DTN in this species. The two subpopulations of retrogradely labelled cells coincided, being distributed within the retinal terminal field attributed to the NOT-DTN, as revealed by contralateral eye injections of HRP.

The commissural cells were located slightly more ventral than the olivary cells in the optic tract. In addition, further caudally, labelled cells and terminals were observed bilaterally in the nuclei prepositus hypoglossi PH and in the medial MVN and lateral LVN vestibular nuclei. Labelled terminals were found in the ipsilateral nucleus reticularis tegmenti pontis NRTP and in the IO with ipsilateral predominance. This study allowed an anatomical delimitation of the NOT-DTN in this opossum species, as defined by the olivary and commissural subpopulations, as well as a hodological evaluation of this region.

The existence of some common anatomical aspects with other mammalian species is discussed. The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae filiform, conical, fungiform, vallate. Scanning electron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process.

The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body.

Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials.

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Scanning electron microscopic structure of the lingual papillae of the common opossum Didelphis marsupialis. Detection of antibodies to Trypanosoma cruzi in the South American opossum Didelphis marsupialis. Stocks of Trypanosoma cruzi belonging to two different zymodemes, one usually associated with silvatic reservoir hosts and the other not normally found in wild reservoir hosts, were used as sources of diagnostic antigens in enzyme-linked immunosorbent assays for the detection of antibodies to T.

Both antigen preparations reacted with antibodies in sera from animals found to be infected by conventional parasitological techniques and also in sera from a proportion of the remaining animals in which it was not possible to detect trypanosomes. Inhibition of the hemorrhagic and proteolytic activities of Lansberg's hognose pit viper Porthidium lansbergii hutmanni venom by opossum Didelphis marsupialis serum: isolation of Didelphis marsupialis 0.

Earlier studies have revealed the ability of sera from several mammals to neutralize the toxic effects of snake venom. The Venezuelan opossum Didelphis marsupialis is one that has been found to inhibit hemorrhagic and proteolytic activities of venoms from many species of snakes. In this article it is shown that the opossum sera and its 0. The protein bands obtained contained molecular weights of approximately 6 to kDa.

These results revealed the presence of proteases inhibitors in the opossum sera fractions and the inhibition of venom activity by opossum sera suggesting a reciprocal adaptation at the molecular level. Antibodies to N. Antibodies to T. Didelphis marsupialis common opossum : a potential reservoir host for zoonotic leishmaniasis in the metropolitan region of Belo Horizonte Minas Gerais, Brazil.

Identification of the zoonotic reservoir is important for leishmaniasis control program. A number of wild animal species may serve as reservoir hosts, including the opossum Didelphis marsupialis.

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Depending on the sero-diagnostic test employed, the sero-prevalence varied between 8. RFLP analysis revealed that two samples contained L.

These data suggest a potential role for the opossum as a reservoir host for zoonotic leishmaniasis in the region. Synaptogenesis in retino-receptive layers of the superior colliculus of the opossum Didelphis marsupialis. Development of the SCr-r neuropil follows a protracted time course and can be divided into three broad stages, which are characterized by I Large extracellular spaces, numerous growth cones that participate rarely in synaptic junctions, vesicles-poor immature synapses PP30 , II Synapses of varied morphology with abundant synaptic vesicles, and small terminals with dark mitochondria and round synaptic vesicles RSD terminals synapsing mostly onto dendritic shafts, flat-vesicles F terminals PP56 , III Sequential appearance of retinal R and pleomorphic-vesicles P terminals and of RSD terminals synapsing onto spine or spine-like processes, appearance of glomerulus-like synaptic arrays synaptic islets PP Helminths of three species of opossums Mammalia, Didelphidae from Mexico.

Abstract From August to November , 68 opossums 8 Didelphis sp. A total of 12, helminths representing 21 taxa were identified 6 trematodes, 2 cestodes, 3 acanthocephalans and 10 nematodes. Sixty-six new locality records, 9 new host records, and one species, the trematode Brachylaima didelphus, is added to the composition of the helminth fauna of the opossums in Mexico. These data, in conjunction with previous records, bring the number of taxa parasitizing the Mexican terrestrial marsupials to Among these species, we recognized a group of helminths typical of didelphids in other parts of the Americas.

This group is constituted by the trematode Rhopalias coronatus, the acanthocephalan Oligacanthorhynchus microcephalus and the nematodes Cruzia tentaculata, Gnathostoma turgidum, and Turgida turgida. In general, the helminth fauna of each didelphid species showed a stable taxonomic composition with respect to previously sampled sites. This situation suggests that the rate of accumulation of helminth species in the inventory of these 3 species of terrestrial marsupials in the Neotropical portion of Mexico is decreasing; however, new samplings in the Nearctic portion of this country will probably increase the richness of the helminthological inventory of this group of mammals.

Isolation and partial characterization of a protein fraction from the opossum Didelphis marsupialis serum, with protecting property against the Bothrops jararaca snake venom. Two separated methods were used to purify a fraction from the opossum Didelphis marsupialis serum able to protect mice against Bothrops jararaca venom. The first of them included an initial batch DEAE-Cellulose ion-exchange of the serum, followed by another ion-exchange chromatography on a Carboxymethyl Sepharose column.

These techniques allowed to obtain a protein fraction which resulted homogeneous in cellulose acetate and conventional polyacrylamide gel electrophoresis. The obtained protein fraction proved to be a glycoprotein according to the positive staining with periodic acid Schiff. Sodium dodecylsulfate polyacrylamide gel electrophoresis of the B-mercaptoethanol-reduced fraction showed heterogeneity and allowed to estimate molecular weights in the range of 42, to 58, daltons.

The obtained serum fraction could effectively block the lethal effect of B. Thaumasioscolex didelphidis n. Eucestoda: Proteocephalidae from the black-eared opossum Didelphis marsupialis from Mexico, the first proteocephalidean tapeworm from a mammal. The new genus differs from all proteocephalidean genera in the morphology of the scolex that is formed by 4 well separated lobes each containing 1 noncircular sucker opening laterally inside the exterolateral cavity, a large-sized body length up to 1 m , a large number of testes, the shape of gravid proglottids that are inversely craspedote the anterior border of a proglottid overlaps the posterior border of a preceding proglottid , eggs in groups mostly of eggs each, and an embryophore bearing digitiform projections on its external surface.

This is the first tapeworm of the Proteocephalidea, the members of which were previously reported exclusively from poikilotherm vertebrates freshwater fishes, amphibians, and reptiles , found in a homoiotherm vertebrate. Trypanosoma cruzi in the opossum Didelphis marsupialis: a study of the correlations and kinetics of the systemic and scent gland infections in naturally and experimentally infected animals.

The genus Didelphis Marsupialia, Didelphidae has the unique capacity of supporting both multiplication cycles of Trypanosoma cruzi simultaneously; besides the intracellular forms, the epimastigotes can be found multiplying and differentiating abundantly in the lumen of the scent glands. The biological significance of the life cycle of T. In order to clarify the mechanisms involved in the colonization of this singular habitat by T. Although all natural infections were stable and long lasting, no infected scent glands were found, indicating that the stability of the systemic infections does not depend on the presence of flagellates in the scent gland.

Parasitism of the scent glands was essentially permanent and bilateral, and its maintenance was independent of circulating parasites. Moreover, the course of the infection differed depending on the source scent glands versus axenic culture-derived of the metacyclic forms.

Our results suggest that parasitism of the SG of D. On the functional anatomy of the nucleus of the optic tract-dorsal terminal nucleus commissural connection in the opossum Didelphis marsupialis aurita. Immunocytochemical methods revealed the presence of GABA in cell bodies and terminals in the nucleus of the optic tract-dorsal terminal nucleus, the medial terminal nucleus, the lateral terminal nucleus and the interstitial nucleus of the superior fasciculus of the opossum Didelphis marsupialis aurita.

Moreover, after unilateral injections of rhodamine beads in the nucleus of the optic tract-dorsal terminal nucleus complex and processing for GABA, double-labelled cells were detected in the ipsilateral complex, up to microns from the injected site, but not in the opposite. Analysis of the distributions of GABAergic and retrogradely-labelled cells throughout the contralateral nucleus of the optic tract-dorsal terminal nucleus showed that the highest density of GABAergic and rhodamine-labelled cells overlapped at the middle third of the complex. Previous electrophysiological data obtained in the opossum had suggested the existence, under certain conditions, of an inhibitory action between the nucleus of the optic tract-dorsal terminal nucleus of one side over the other.

The absence of GABAergic commissural neurons may imply that this inhibition is mediated by an excitatory commissural pathway that activates GABAergic interneurons. Trypanosoma Megatrypanum freitasi, a parasite of marsupials of the genus Didelphis , has been found to undergo in the lumen of the scent anal glands of its vertebrate host, a cycle such as usually occurs in the intestinal tract of the insect vectors of trypanosomatids and similar to what has been reported for Trypanosoma Schizotrypanum cruzi. The invertebrate host of Trypanosoma freitasi is still unknown.

Developmental stages of the trypanosome in its mammalian host, especially the dividing epimastigotes, multinucleate plasmodial forms and rosettes found in the lumen of the scent glands of a naturally infected Didelphis marsupialis are described and illustrated. New methodology for the obtainment of antibothropic factors from the South American opossum Didelphis marsupialis and jararaca snake Bothrops jararaca.

The antibothropic factor ABF from D. Two months after the implantation of the balls, approximately 15 ml of seromatous fluid from D. ABF isolated from SFDm or from serum by ion-exchange chromatography showed identical chromatographic and electrophoretic profiles. ABF fromboth sources displayed very similar antihemorrhagic and anticaseinolytic activities against Bjv. In the case of B. Both serum and SFBj inhibited Bjv hemorrhagic activity. We conclude that this new methodology is very suitable for continuously obtaining opossum ABF and SFBj, in large scale and in an easier way, avoiding animal suffering and eventual sacrifice.

Another Trypanosoma, distinct from T. Epimastigotes were found multiplying in the anal glands and in hemocultures of an opossum ; rare metacyclics were seen in the cultures. The flagellate is possibly T. New findings on the purification and characterization of an anti-bothropic factor from Didelphis marsupialis opossum serum. We have used DEAE-Sephacel and Sephacryl S to separate protein fractions from Didelphis marsupialis serum capable of protecting mice from the lethal effect of Bothrops jararaca venom. The fractions separated were homogeneous by conventional electrophoresis using cellulose acetate and polyacrylamide; however, they were heterogeneous on PAGE-SDS, showing similar electrophoretic patterns with or without mercaptoethanol.

The protein bands obtained were glycoproteins with a molecular weight of 42, to 58, Daltons. Trypanosoma cruzi infection in the opossum Didelphis marsupialis: absence of neonatal transmission and protection by maternal antibodies in experimental infections. The high rate of natural Trypanosoma cruzi infection found in opossums does not always correlate with appreciable densities of local triatomid populations.

One alternative method which might bypass the invertebrate vector is direct transmission from mother to offspring. This possibility was investigated in five T. The influence of maternal antibodies transferred via lactation, on the course of experimental infection, was also examined. Our results show that neonatal transmission is probably not responsible for the high rate of natural T. In addition antibodies of maternal origin confer a partial protection to the young. This was demonstrated by the finding of a double prepatency period and 4, 5 fold lower levels of circulating parasites, in experimentally infected pouch young from infected as compared to control uninfected mothers.

On the other hand, the duration of patent parasitemia was twice as long as that observed in the control group. The horizontal optokinetic reflex of the opossum Didelphis marsupialis aurita : physiological and anatomical studies in normal and early monoenucleated specimens. In the opossum the symmetrical binocular horizontal optokinetic nystagmus gives way to an asymmetrical monocular reflex: the nasotemporal NT stimulation yielding lower gain than the temporonasal TN.

In adults, monocularly enucleated at postnatal days pnd , the gain of NT responses is markedly increased, approaching that of TN. Severe cell loss was detected in the nucleus of the optic tract NOT on the deafferented side in early monoenucleated specimens.

In normal animals retinal afferents to the NOT are all crossed, while in animals enucleated at pnd sparse uncrossed retinal elements were observed. Although this abnormal projection might influence the increased NT response in this subgroup, it is argued that the increased symmetry in monoenucleated opossums may be the result of changes mediated by the commissural connection between both NOTs.

Inhibition of the hyperalgesic activity of Bothrops jararaca venom by an antibothropic fraction isolated from opossum Didelphis marsupialis serum. The antibothropic fraction ABF already isolated from Didelphis marsupialis serum, inhibits the haemorrhagic, oedematogenic, myonecrotic and lethal activities of Bothrops jararaca venom Bjv. The aim of this work was to verify the capability of ABF to inhibit the hyperalgesic activity of Bjv.

Intraplantar injection of Bjv induced hyperalgesia in a time- and dose-dependent manner and ABF administered in situ concomitantly with Bjv or i. This same effect was observed when ABF was intravenously injected at 5 and 15 min after Bjv. Our results show that ABF inhibits also the hyperalgesia induced by Bjv. Photoreceptors in a primitive mammal, the South American opossum , Didelphis marsupialis aurita: characterization with anti-opsin immunolabeling. The retinas of placental mammals appear to lack the large number and morphological diversity of cone subtypes found in diurnal reptiles.

We have now studied the photoreceptor layer of a South American marsupial Didelphis marsupialis aurita by peanut agglutinin labeling of the cone sheath and by labeling of cone outer segments with monoclonal anti-visual pigment antibodies that have been proven to consistently label middle-to-long wavelength COS-1 and short-wavelength OS-2 cone subpopulations in placental mammals.

Besides a dominant rod population max. The outer segments of three cone subtypes were labeled by COS a double cone with a principal cone containing a colorless oil droplet, a single cone with oil droplet, and another single cone. A second group of single cones lacking oil droplets was labeled by OS-2 antibody. The topography of these cone subtypes showed striking anisotropies. The COS-1 labeled single cones without oil droplets were found all over the retina and constituted the dominant population in the area centralis located in the temporal quadrant of the upper, tapetal hemisphere.

The two spectral types of single cones resemble those of dichromatic photopic systems in most placental mammals. The additional set of COS-1 labeled cones is a distinct marsupial feature. The presence of oil droplets in this cone subpopulation, its absence in the area centralis, and the correlation with the non-tapetal inferior hemisphere suggest a functional specialization, possibly for mesopic conditions.

Thus, sauropsid features have been retained but probably with a modified function. A note on the relative rates of degeneration in the crossed and the uncrossed retinofugal fibres in the opossum Didelphis marsupialis. The rates at which the crossed and the uncrossed components of the retinofugal pathway degenerate in Didelphis has been studied by light and electron microscopical methods.

We have found that in Didelphis , as in Monodelphis the two components can be clearly distinguished at the level of the chiasm. However, in contrast to the situation previously described for Monodelphis, where the uncrossed component degenerates more rapidly than the crossed, both components degenerate at the same rate.

The aim of this study was to determine the morphometric values of the skull and the mandible of the common opossum from the Caribbean island of Trinidad and Tobago. The skulls and mandibles were obtained from ten opossums captured for research purposes. Some anatomical landmarks of the skulls and mandibles were identified and measured. The results were important for identification of the common opossum via comparison and discussion of our results with that of other marsupial species. Furthermore, the results had clinical importance with regard to regional nerve blocks of the infraorbital, inferior alveolar, and mental nerves for dental extraction and head surgery.

This study concluded that by using the anatomical landmarks of the infraorbital and mental foramina it will be easier for the veterinarian surgeons during the application of local anesthetic agent for the infraorbital, inferior alveolar, and mental nerve blocks. The animal died 5 weeks after inoculation. Autopsy revealed signs of visceral leishmaniasis along with amastigote parasite form in Kupffer cells and spleen macrophages. Amyloid deposits in liver and spleen were demonstrated by histological staining and electron microscopy. The rapid death was considered a consequence of a secondary, reactive amyloidosis.

Neutralization of the oedematogenic activity of Bothrops jararaca venom on the mouse paw by an antibothropic fraction isolated from opossum Didelphis marsupialis serum. The pharmacological modulation of mice paw oedema produced by Bothrops jararaca venom BJV has been studied. BJV heated at degrees C for 5 or 15 min blocked local hemorrhage and caused partial inhibition of its oedematogenic activity. The oedema produced by histamine, serotonin, PAF-acether or leukotriene C4 was not inhibited. Didelphis albiventris and D. In the Araucaria moist forest of Southern Brazil these species are sympatric and they might potentially compete having similar ecology.

For this reason, they are ideal biological models to address questions about ecological character displacement and how closely related species might share their geographic space. Little is known about how two morphologically similar species of marsupials may affect each other through competition, if by competitive exclusion and competitive release. We combined ecological niche modeling and geometric morphometrics to explore the possible effects of competition on their distributional ranges and skull morphology. Ecological niche modeling was used to predict their potential distribution and this method enabled us to identify a case of biotic exclusion where the habit generalist D.

The morphometric analyses show that a degree of shape discrimination occurs between the species, strengthened by allometric differences, which possibly allowed them to occupy marginally different feeding niches supplemented by behavioral shift in contact areas. Overlap in skull morphology is shown between sympatric and allopatric specimens and a significant, but weak, shift in shape occurs only in D.

This could be a residual evidence of a higher past competition between both species, when contact zones were possibly larger than today. Therefore, the specialist D. On the other hand, when there is niche diversification e. Seed dispersal of Diospyros virginiana in the past and the present: Evidence for a generalist evolutionary strategy. Several North American trees are hypothesized to have lost their co-evolved seed disperser during the late-Pleistocene extinction and are therefore considered anachronistic.

We tested this hypothesis for the American persimmon Diospyros virginiana by studying the effects of gut passage of proposed seed dispersers on seedling survival and growth, natural fruiting characteristics, and modern animal consumption patterns. We tested gut passage effects on persimmon seeds using three native living species, the raccoon Procyon lotor , Virginia opossum Didelphis virginiana , and coyote Canis latrans , and two Pleistocene analogs; the Asian elephant Elephas maximus and alpaca Vicugna pacos.

Persimmon seeds excreted by raccoons, coyotes, and elephants survived gut transit. Gut passage did not affect sprouting success, but did tend to decrease time to sprout and increase seedling quality. Physaloptera turgida. Virginia opossum. Show All Keywords. Life Cycle of Oligacanthorhynchus tortuosa Oligacanthorhynchidae , an Acanthocephalan of the Characterization of Erysipelothrix rhusiopathiae Isolated from an Opossum Didelphis virginiana Assessment of temporal partitioning in foraging patterns of syntopic Virginia Temperature sensor evaluation of opossum winter activity.

Besnoitia darlingi Infection in a Virginia Opossum Didelphis virginiana. Subscribe to BioOne Complete. Receive erratum alerts for this article. Receive alerts when this article is cited. Skickas inom vardagar. The North American opossum Didelphis virginiana generally is regarded as an important animal, phylogenetically. It is considered to represent a prototype marsupial and closely resembles fossil didelphids Tyndale-Biscoe Numerous studies concerning the reproductive biology, embryology, and neurobiology of the opossum have been published.

More recently, Didelphis has become popular as an animal model for gastroenterological studies because of the remarkable anatomical and physiological similarities of the esophagus as compared to that of man. Most of the studies of early development have concentrated on early cleavage stages and the formation of the three primary germ layers Hartman , and fetal membranes Selenka ; McCrady