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At least 235 records · Page 13Linked to original sources

PubMed1983

Life cycle and development of Lagochilascaris sprenti (Nematoda: ascarididae) from opossums (Marsupialia: didelphidae) in Louisiana.

The life cycle of Lagochilascaris sprenti, a species which occurs in the stomach of opossums (Didelphis virginiana) in Louisiana, was determined. The larva in the egg developed to the infective stage after eggs from the feces of infected animals were in culture about 30 days. When eggs containing infective larvae were fed to mice, the larvae hatched, penetrated the intestinal mucosa, migrated through the liver and lungs, and eventually reached the skeletal muscles where they became encapsulated. Larvae were also found encapsulated in the skeletal muscles of rats, gerbils, hamsters, monkeys, and a rabbit fed infective eggs. No larvae were found in the muscles of opossums fed infective eggs. However, when opossums were fed mice with 39- to 204-day-old Lagochilascaris infections, larvae developed in the gastric mucosa to the adult stage within 21 days. Adult worms inhabited cavities in the submucosa of the stomach from which they could migrate through openings into the lumen. One to three abscesses, each containing a single adult worm, were found in the musculature of 16.4% of the mice fed infective eggs.

Animals↗

PubMed1983

Lagochilascaris sprenti sp. n. (Nematoda: ascarididae) from the opossum, Didelphis virginiana (Marsupialia: didelphidae).

Sixty-eight specimens of Lagochilascaris from the stomach of seven naturally-infected opossums from Louisiana were described as Lagochilascaris sprenti sp. n. Observations were also made on adult worms of both sexes recovered from experimentally-infected opossums and mice. The new species differs from the four previously described species of Lagochilascaris in the length of the spicules, number of pits on the circumference of the egg, and position of the vulva. The spicules are shorter in L. sprenti than in L. turgida and L. buckleyi. The number of surface pits in the eggshell at the circumference of the egg is 24 to 31 in L. sprenti, less in L. minor (15-26), and more in L. major (33-45). In worms of equal length, the vulva is consistently about 1 mm further anteriad in L. sprenti than it is in L. minor or L. major.

Animals↗

PubMed1982

Fine structure of the interstitium of the epididymis of the South American Opossum (Didelphis azarae, Marsupialia).

The interstitial space of the ductus epididymidis of the opossum (D. azarae), contains fibers and cell elements of the connective tissue, smooth muscle cells and amyelinic nerve fibers. This structure, studied through TEM, is similar to the fine structure of the interstitium of the epididymis in rodents. However, the normal occurrence of mast cells in the interstitial space of the ductus epididymidis in opossum, seems to be a peculiar morphological characteristic of this species.

Animals↗

PubMed1994

[The topography of the pancreas of Monodelphis domestica (Marsupialia)].

Shape and position of the pancreas of Monodelphis domestica are described in situ after fixation of the animals with Bouin's fluid. The right lobe of the pancreas is the smallest of the three organ parts. The body of the pancreas is placed in a transverse position in the cranial area of the peritoneal cavity. Ventral access to it is relatively difficult due to the position of the greater parts of the body dorsal to the stomach. In contrast, the left lobe reaches far caudad. Typical for Monodelphis domestica, it extends into the omental veil, offering the possibility of a relatively easy surgical access to pancreas parenchyma in this species. The data are discussed in view of reports about other small laboratory animals. Some remarks are made as a proposal for the procedure of laparotomy.

Animals↗

PubMed1993

Hematology and erythrocyte biochemistry of spectacled hare-wallaby, Lagorchestes conspicillatus (Macropodidae Marsupialia).

Hematology and the red cell enzymes, metabolites, and rates of lactate production were measured in a small marsupial, the spectacled hare-wallaby Lagorchestes conspicillatus. In common with other marsupials of similar body weights, the red cells of this wallaby were found to have low levels of ATP and higher levels of 2,3-diphosphoglycerate (DPG) and produced no lactate when incubated with inosine. One of the five animals examined was suffering from anemia (hematocrit of 22.0% and hemoglobin concentration of 7.2 g/dl compared with the normal values of 46.6% and 15.8 g/dl, respectively); its red cells had almost twice the concentrations of ATP and DPG and had significantly higher activities of several enzymes of the glycolytic pathway.

2,3-Diphosphoglycerate↗

PubMed1995

Immunohistochemical demonstration of adenohypophyseal hormones during postnatal ontogenesis in the Gray Short-tailed Opossum, Monodelphis domestica (marsupialia).

Antibodies against human FSH, LH, TSH, ACTH, GH, PRL, and MSH were applied to paraffin sections of newborn (< 1) and pouch-young individuals with the age of 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 13, 14 days, respectively (D1, D2,...). In the pouch-young, the antibody reactions occurred only in the pars distalis of the adenohypophysis. The D < 1 individuals included, the reactions were strong for ACTH, moderate/strong for GH, and moderate for MSH. Reactivity for TSH was recorded first in D2 specimens, for LH in D3 animals, for FSH and PRL in D8 animals. There was a remarkable regional distribution of reactive cells within the pars distalis: reactions for ACTH were localized mainly in the rostral area, those for GH were most prominent caudally. The chronological sequence of appearance of the specific hormone-producing cells in the pouch-young generally is in accordance with the characteristic pattern known in other mammalian species. The late onset of differentiation of some cell types indicates the research possibilities that postnatal Monodelphis domestica can offer in the field of ontogenetic studies on the mammalian endocrine system.

Animals↗

PubMed1994

"Not proper mammals": immunity in monotremes and marsupials.

Immune systems and responses in Monotremata and Marsupialia are reviewed. The Monotremata (Prototheria) are egg-laying mammals. Few studies have been carried out on monotremes. The structure of the lymph nodules of Tachyglossus aculeatus is unusual, and the occurrence of IgG in this species is noteworthy: IgG has not yet been found in any non-mammal. A number of Marsupialia (Metatheria) species have been used as immunological models. Generally immune responses are somewhat slower and less accentuated than in placental (eutherian) mammals. Of interest is the presence of cervical and thoracic thymuses in several marsupials. Marsupials are born very immature and possess rather rudimentary immune responses at birth: the neonate may provide a helpful model for immune ontogenesis. Marsupials have a full repertoire of immunoglobulin classes. MHC Class II (but not Class I) gene polymorphism may be limited. Studies using molecular biology techniques are awaited to elucidate the structural organization of the immune components and to determine similarities and differences between marsupials' and other animals' immune systems.

Animals↗

PubMed1982

Receptor in group C and G streptococci detects albumin structures present in mammalian species.

The presence of albumin structures with the capacity to bind to a surface receptor in group C and G streptococci was studied in serum samples from 45 mammalian species representing 15 different orders, using an inhibition assay. The ability of animal sera to inhibit the uptake of radiolabeled human serum albumin by the streptococci indicated the presence of such albumin structures. Positive reactions were found in species of most orders tested, with Marsupialia as a notable exception. All Carnivora sera tested were strongly positive. In some orders such as Artiodactyla both positive and negative species were identified. Serum samples from 62 bird species representing 15 orders and from 5 fish species were also tested in the inhibition assay. None of these serum samples was capable of inhibiting the uptake of human serum albumin by streptococci. Some differences were also noted in the results obtained with group C and G streptococci from human and bovine sources, respectively, indicating the presence of two types of receptors. The present studies suggest a phylogenetic origin of albumin structures with affinity for the streptococcal receptor to a period after the divergence of Marsupialia from the other mammalian orders.

Animals↗

PubMed2004

Number and nuclear localisation of nucleoli in mammalian spermatocytes.

In seven mammalian species, including man, the position and number of nucleoli in pachytene spermatocyte nuclei were studied from electron microscope (EM) nuclear sections or bivalent microspreads. The number and position of the nucleolar organiser regions (NORs) in mitotic and meiotic chromosomes were also analysed, using silver staining techniques and in situ hybridisation protocols. The general organisation of pachytene spermatocyte nucleoli was almost the same, with only minor morphological differences between species. The terminal NORs of Thylamys elegans (Didelphoidea, Marsupialia), Dromiciops gliroides (Microbiotheridae, Marsupialia), Phyllotys osgoodi (Rodentia, Muridae) and man, always gave rise to peripheral nucleoli in the spermatocyte nucleus. In turn, the intercalated NORs from Octodon degus, Ctenomys opimus (Rodentia, Octodontidae) and Chinchilla lanigera (Rodentia, Cavidae), gave rise to central nucleoli. In species with a single nucleolar bivalent, just one nucleolus is formed, while in those with multiple nucleolar bivalents a variable number of nucleoli are formed by association of different nucleolar bivalents or NORs that occupy the same nuclear peripheral space (Phyllotis and man). It can be concluded that the position of each nucleolus within the spermatocyte nucleus is mainly dependent upon: (1) the position of the NOR in the nucleolar bivalent synaptonemal complex (SC), (2) the nuclear pathway of the nucleolar bivalent SC, being both telomeric ends attached to the nuclear envelope, and (3) the association between nucleolar bivalents by means of their NOR-nucleolar domains that occupy the same nuclear space. Thus, the distribution of nucleoli within the nuclear space of spermatocytes is non-random and it is consistent with the existence of a species-specific meiotic nuclear architecture.

Animals↗

PubMed2002

Comparative patterns of postcranial ontogeny in therian mammals: an analysis of relative timing of ossification events.

Data on the relative sequence of ossification of postcranial elements for eight therian mammals (Myotis lucifugus, Homo sapiens, Rattus norvegicus, Mus musculus, Mesocricetus auratus, Cavia porcellus, Didelphis albiventris, and Sminthopsis macroura) and three outgroups (Chelydra serpentina, Alligator mississippiensis, and Lacerta vivipara) were taken from the literature. For each species, a matrix was constructed in which the relative timing of the onset of ossification in 24 elements was summarized. This resulted in 276 event pairs (characters) for each species. Thirty-three (33.3)% of the characters examined are uniform across all taxa, 16.3% are variable but uninformative in the phylogeny, and 50.4% potentially deliver diagnostic features for clades of two or more taxa. In all species examined, the clavicle is the first bone to appear. Placentalia is not unequivocally diagnosed by the state of any event pair, while Marsupialia has the largest amount of autapomorphies with 18. The acceleration in the timing of ossification of the scapula in relation to the hindlimb in marsupials is most probably causally correlated to movements after birth and during early phases of pre-weaning life. Marsupials are almost unique among amniotes in that the earliest onset of ossification of at least one element among carpals and among tarsals is simultaneous. Three parsimony analyses, each one with a different reptilian taxon as outgroup, were performed using event pairs as characters. In all cases, results were incongruent with the phylogeny of the studied taxa.

Age Factors↗

PubMed2002

Ontogenetic and phylogenetic transformations of the ear ossicles in marsupial mammals.

This study is based on the examination of histological sections of specimens of different ages and of adult ossicles from macerated skulls representing a wide range of taxa and aims at addressing several issues concerning the evolution of the ear ossicles in marsupials. Three-dimensional reconstructions of the ear ossicles based on histological series were done for one or more stages of Monodelphis domestica, Caluromys philander, Sminthopsis virginiae, Trichosurus vulpecula, and Macropus rufogriseus. Several common trends were found. Portions of the ossicles that are phylogenetically older develop earlier than portions representing more recent evolutionary inventions (manubrium of the malleus, crus longum of the incus). The onset of endochondral ossification in the taxa in which this was examined followed the sequence; first malleus, then incus, and finally stapes. In M. domestica and C. philander at birth the yet precartilaginous ossicles form a supportive strut between the lower jaw and the braincase. The cartilage of Paauw develops relatively late in comparison with the ear ossicles and in close association to the tendon of the stapedial muscle. A feeble artery traverses the stapedial foramen of the stapes in the youngest stages of M. domestica, C. philander, and Sminthopsis virginiae examined. Presence of a large stapedial foramen is reconstructed in the groundplan of the Didelphidae and of Marsupialia. The stapedial foramen is absent in all adult caenolestids, dasyurids, Myrmecobius, Notoryctes, peramelids, vombatids, and phascolarctids. Pouch young of Perameles sp. and Dasyurus viverrinus show a bicrurate stapes with a sizeable stapedial foramen. Some didelphids examined to date show a double insertion of the Tensor tympani muscle. Some differences exist between M. domestica and C. philander in adult ossicle form, including the relative length of the incudal crus breve and of the stapes. Several differences exist between the malleus of didelphids and that of some phalangeriforms, the latter showing a short neck, absence of the lamina, and a ventrally directed manubrium. Hearing starts in M. domestica at an age in which the external auditory meatus has not yet fully developed, the ossicles are not fully ossified, and the middle ear space is partially filled with loose mesenchyme. The ontogenetic changes in hearing abilities in M. domestica between postnatal days 30 and 40 may be at least partially related to changes in middle ear structures.

Animals↗

PubMed1998

Higher taxonomic relationships among extant mammals based on morphology, with selected comparisons of results from molecular data.

Until a few decades ago, phylogenetic relationships among placental orders were ambiguous and usually depicted to radiate as an unresolved "bush." Resolution of this bush by various workers has been progressing slowly, but with promising results corroborated by nondental, dental, and molecular characters. In this study we continue to seek resolution. A total of 258 nondental and 2 dental characters was analyzed by PAUP and MacClade on 39 vertebrate taxa (3 reptiles, 1 nonmammalian therapsid, and 35 mammals; 20 of the mammals are extant and 15 are extinct) to study higher taxonomic relationships with emphasis on Placentalia (Eutheria). About two-thirds of the characters are osteological, the rest concern soft tissues, including myological but excluding molecular characters (most are our data, the rest are from the literature). Cladistic analysis included all 39 taxa (fossil taxa help to evaluate polarities of characters) and all characters were given equal weight. Extant Mammalia are divided into Prototheria and Theria, the latter into Marsupialia and Placentalia. Placentalia comprises Xenarthra and Epitheria. Within Epitheria, Lipotyphla and Preptotheria (emended) are sister-taxa. Preptotherian taxa group into: ungulate-related taxa and various nonungulates. The former include Carnivora, Pholidota, Tubulidentata, Artiodactyla, Cetacea, Perissodactyla, Hyracoidea, Proboscidea, and Sirenia. A possible association to embrace Lagomorpha, Rodentia, Macroscelidea, Scandentia, Primates, Chiroptera, and Dermoptera is suggested. Significant differences between our findings and those of recent investigators include the dissociation of Pholidota from Xenarthra and the plesiomorphous position of Lipotyphla within Epitheria. Congruence between morphological and molecular results is closer than previously reported.

Animals↗

PubMed1995

Reduction of metabolic rate and thermoregulation during daily torpor.

Physiological mechanisms causing reduction of metabolic rate during torpor in heterothermic endotherms are controversial. The original view that metabolic rate is reduced below the basal metabolic rate because the lowered body temperature reduces tissue metabolism has been challenged by a recent hypothesis which claims that metabolic rate during torpor is actively downregulated and is a function of the differential between body temperature and ambient temperature, rather than body temperature per se. In the present study, both the steady-state metabolic rate and body temperature of torpid stripe-faced dunnarts, Sminthopsis macroura (Dasyuridae: Marsupialia), showed two clearly different phases in response to change of air temperature. At air temperatures between 14 and 30 degrees C, metabolic rate and body temperature decreased with air temperature, and metabolic rate showed an exponential relationship with body temperature (r2 = 0.74). The Q10 for metabolic rate was between 2 and 3 over the body temperature range of 16 to 32 degrees C. The difference between body temperature and air temperature over this temperature range did not change significantly, and the metabolic rate was not related to the difference between body temperature and air temperature (P = 0.35). However, the apparent conductance decreased with air temperature. At air temperatures below 14 degrees C, metabolic rate increased linearly with the decrease of air temperature (r2 = 0.58) and body temperature was maintained above 16 degrees C, largely independent of air temperature. Over this air temperature range, metabolic rate was positively correlated with the difference between body temperature and air temperature (r2 = 0.61). Nevertheless, the Q10 for metabolic rate between normothermic and torpid thermoregulating animals at the same air temperature was also in the range of 2-3.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1979

Ascorbic acid biosynthesis in the mammalian kidney.

The egg-laying mammals (Prototheria) synthesize L-ascorbic acid only in kidney, as is characteristic of reptiles. Bandicoots (Marsupialia) synthesize it in both kidney and liver. 2 other species of marsupials (kangaroos) synthesize it primarily in liver, but some individuals also synthesize in kidney.

Animals↗

PubMed1990

DNA hybridization, cladistics, and the phylogeny of phalangerid marsupials.

Single-copy DNA/DNA hybridization experiments and numerical cladistic analyses of anatomical characters were used to investigate relationships among nine phalangerid (Marsupialia) species from four different genera. Both rate-dependent and rate-independent analyses of molecular data indicate that species of Trichosurus from one clade and that Strigocuscus, Phalanger, and Spilocuscus form a second. Within the latter group, Spilocuscus is excluded from a Strigocuscus-Phalanger clade, which, in turn, is not fully resolved on a jackknife strict consensus tree. Minimum-length Dollo, Wagner, and Camin-Sokal parisomy trees based on 35 anatomical characters, in contrast, suggest placement of Strigocuscus with Trichosurus rather than with Spilocuscus and Phalanger. However, there are two derived characters that support the alternative arrange of Strigocuscus with Spilocuscus and Phalanger and one character that further unites Strigocuscus and Phalanger. Thus, DNA hybridization results are not inconsistent with the distribution of derived character states among anatomical characters, only with minimum-length trees based on character data.

Animals↗

PubMed1987

High mobility group (HMG) proteins in the tammar wallaby Macropus eugenii: quantitative variations between tissues and testis-specific co-extracted proteins.

1. Tammar wallaby (Macropus eugenii, Marsupialia) proteins with similar electrophoretic mobilities to calf non-histone chromosomal proteins HMG 1, 2, 14 and 17 are perchloric acid extracted from whole tissues (liver, kidney, spleen, brain and testis) and purified liver nuclei (using PCA or 0.35 M NaCl). 2. Tammar and calf HMG 1 have similar amino acid compositions. 3. Two testis-specific basic proteins co-extracting with HMG-like proteins from both tammar and red kangaroo (Megaleia rufa) are found in whole testis, purified testis nuclei, but not epididymis. 4. Tammar HMG 2 separates into two components on both acid urea and SDS gels. The larger, more basic protein, HMG 2b, is relatively abundant in proliferating tissues (testis, spleen).

Amino Acids↗

PubMed1989

A marsupial phosphoglycerate kinase (PGK) processed pseudogene.

A clone that cross-hybridized with a full-length human cDNA PGK probe was isolated from a hill kangaroo (Macropus robustus: Marsupialia) lambda EMBL4 EcoRI genomic library. The clone was sequenced and demonstrated to be a pseudogene, with two deletions (one of 3 bases, the other 24 bases long), one single base insertion, and a nonsense mutation with respect to the functional human X-linked gene. It is flanked by terminal repeats in the 5' and 3' noncoding regions, but it has no 3' poly(A) remnant. The 3' untranslated region has a 34-bp sequence, with 29 bp homologous to the human 3' untranslated region. The overall percentage homology with the mouse and human X-linked PGK indicates that this pseudogene is probably more closely related to eutherian X-linked PGK genes than to the autosomal form. The results also suggest that pseudogenes are of considerable antiquity (greater than 100 MYr) in the mammalian lineage.

Animals↗

PubMed2000

Helminth communities of pademelons, Thylogale stigmatica and T. thetis from eastern Australia and Papua New Guinea.

Gastrointestinal helminths were collected from pademelons of the genus Thylogale (Marsupialia: Macropodidae) in eastern Australia and Papua New Guinea. Examined were 12 Thylogale stigmatica stigmatica and 13 T. s. wilcoxi, the latter subdivided into eight specimens from the northern limit of their distribution and five from southern areas, all from eastern Queensland, Australia, one T. s. oriomo from Papua New Guinea and ten T. thetis from southeastern Queensland and northern New South Wales, Australia. Six species of cestodes and 40 species of nematodes were found. The helminth community of T. s. stigmatica was similar to that found in northern specimens of T. s. wilcoxi, while differences from the helminth community present in southern T. s. wilcoxi could be accounted for by parasites acquired from sympatric T. thetis. Thylogale thetis harboured a community of helminths distinct from but related to that in T. stigmatica. The evidence suggests that all subspecies of T. stigmatica examined share a common helminth community, but that in areas of sympatry, T. stigmatica and T. thetis share some of their parasites.

Animals↗