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At least 19 recordsLinked to original sources
PubMed1998

The origin of the Australasian marsupial fauna and the phylogenetic affinities of the enigmatic monito del monte and marsupial mole.

Alternative hypotheses in higher-level marsupial systematics have different implications for marsupial origins, character evolution, and biogeography. Resolving the position of the South American monito del monte (Order Microbiotheria) is of particular importance in that alternate hypotheses posit sister-group relationships between microbiotheres and taxa with disparate temporal and geographic distributions: pediomyids; didelphids; dasyuromorphians; diprotodontians; all other australidelphians; and all other marsupials. Among Australasian marsupials, the placement of bandicoots is critical; competing views associate bandicoots with particular Australasian taxa (diprotodontians, dasyuromorphians) or outside of a clade that includes all other Australasian forms and microbiotheres. Affinities of the marsupial mole are also unclear. The mole is placed in its own order (Notoryctemorphia) and sister-group relationships have been postulated between it and each of the other Australasian orders. We investigated relationships among marsupial orders by using a data set that included mitochondrial and nuclear genes. Phylogenetic analyses provide support for the association of microbiotheres with Australasian marsupials and an association of the marsupial mole with dasyuromorphs. Statistical tests reject the association of diprotodontians and bandicoots together as well as the monophyly of Australasian marsupials. The origin of the paraphyletic Australasian marsupial fauna may be accounted for by (i) multiple entries of australidelphians into Australia or (ii) bidirectional dispersal of australidelphians between Antarctica and Australia.

Animals↗
PubMed1984

Gene mapping in marsupials and monotremes. I. The chromosomes of rodent-marsupial (Macropus) cell hybrids, and gene assignments to the X chromosome of the grey kangaroo.

Somatic cell genetic mapping of marsupial and monotreme species will greatly extend the power of comparative gene mapping to detect ancient mammalian gene arrangements. The use of eutherian-marsupial cell hybrids for such mapping is complicated by the frequent retention of deleted and rearranged marsupial chromosomes. We used staining techniques, involving the fluorochromes Hoechst 33258 and chromomycin A3, to facilitate rapid and unequivocal identification of marsupial chromosomes and chromosome segments and to make chromosome assignment and regional localization of marsupial genes possible. Chromosome segregation in rodent-macropod hybrids was consistent with preferential loss of the marsupial complement. The extent of loss was very variable. Some hybrids retained 30% of the marsupial complement; some retained small centric fragments; and some, no cytologically identifiable marsupial material. We examined the chromosomes and gene products of a number of rodent-grey kangaroo Macropus giganteus hybrids, and have assigned the genes Pgk-A (phosphoglycerate kinase-A), Hpt (Hypoxanthine-phosphoribosyl transferase), and Gpd (Glucose-6-phosphate dehydrogenase) to the long arm of the kangaroo X chromosome, and provisionally established the gene order Pgk-A--Hpt--Gpd.

Animals↗
PubMed1981

Macropodid marsupial testicular gonadotrophin receptors and their use in assays for marsupial gonadotrophins.

The interactions of several mammalian follicle-stimulating hormones and luteinizing hormones with specific gonadotrophin receptors in macropodid marsupial testicular homogenates were investigated with a view to developing radioreceptor assays for marsupial FSH and LH. Testes from Eastern grey kangaroos and tammar wallabies possessed high affinity (dissociation constant congruent to 10(-10) mol/l) saturable receptor sites which were highly specific for LH or FSH. Luteinizing hormone receptor sites bound only highly purified LH preparations (human, ovine and rat) but did not bind highly purified FSH, TSH or prolactin while FSH receptor sites were equally specific for highly purified FSH preparations. These sites demonstrated a degree of species specificity in that marsupial pituitary extracts were relatively more potent in these assays than in assays using gonadotrophin receptors from rat testes. Serum from hypophysectomized female tammar wallabies had little effect on the slope and position of the LH standard curve but significantly depressed the dose-response curve for FSH. For this reason it was not possible to develop a radioreceptor assay for serum FSH using marsupial testicular FSH receptors. However, gonadotrophin receptors from both rat and marsupial testes have been employed in the successful development of radioreceptor assays for marsupial pituitary LH and FSH and marsupial serum LH.

Animals↗
PubMed1979

Marsupial--mouse cell hybrids containing fragments of the marsupial X chromosome.

Hybrids were obtained from fusions of HPRT-deficient mouse fibroblasts and marsupial lymphocytes. These hybrids retained no identifiable marsupial chromosomes, but all expressed the marsupial form of HPRT. Half the clones also expressed marsupial PGK-A, and half of these also marsupial G6PD; no other marsupial allozyme markers were detected. Since G6PD is known to be sex linked in these species, we conclude that Hpt and Pgk-A are also located on the X chromosome and the markers lie in the order Hpt-Pgk-A-Gpd.

Animals↗
PubMed1995

Marsupialization of cystic ameloblastoma: a clinical and histopathologic study of the growth characteristics before and after marsupialization.

PURPOSE: This study evaluated the effectiveness of marsupialization for the treatment of cystic ameloblastoma. MATERIALS AND METHODS: Clinical and histologic examination of 24 cystic ameloblastomas were performed before and after marsupialization. RESULTS: Clinically and radiographically, the effect of marsupialization was evaluated as extremely effective (five cases), effective (11 cases), and noneffective (eight cases). Marsupialization was most effective in teenaged patients. In three cases, the tumor disappeared macroscopically, and further surgery was not done. Histologically, the growth characteristics of the tumor were classified into expansive and invasive types. Cytologic pattern was classified into three types according to the outer cell layer of the tumor parenchyme: cuboidal cell, columnar cell, and basal cell. Premarsupialization, the expansive pattern with the cuboidal cell type was dominant, whereas for postmarsupialization many cases that had been expansive changed to an invasive type showing columnar or basal cell types. CONCLUSION: Marsupialization was found to be useful as a preliminary treatment of the cystic ameloblastoma. However, it must be borne in mind that following marsupialization the tumor still has a potential to infiltrate into the surrounding tissues.

Adolescent↗
PubMed2004

Marsupial relationships and a timeline for marsupial radiation in South Gondwana.

Recent marsupials include about 280 species divided into 18 families and seven orders. Approximately 200 species live in Australia/New Guinea. The remaining species inhabit South America with some of these secondarily ranging into North America. In this study, we examine marsupial relationships and estimate their divergences times using complete mitochondrial (mt) genomes. The sampling, which includes nine new mtDNAs and a total number of 19 marsupial genomes, encompasses all extant orders and 14 families. The analysis identified a basal split between Didelphimorphia and remaining orders about 69 million years before present (MYBP), while other ordinal divergences were placed in Tertiary times. The monotypic South American order Microbiotheria (Dromiciops gliroides, Monito del Monte) was solidly nested among its Australian counterparts. The results suggest that marsupials colonized Australia twice from Antarctica/South America and that the divergence between Microbiotheria and its Australian relatives coincided with the geological separation of Antarctica and Australia. Within Australia itself, several of the deepest divergences were estimated to have taken place close to the Eocene/Oligocene transition.

Animals↗
PubMed1983

Neocortical projections of the suprageniculate and posterior thalamic nuclei in the marsupial brush-tailed possum, Trichosurus vulpecula (Phalangeridae), with a comparative commentary on the organization of the posterior thalamus in marsupial and placental mammals.

Axonal transport methods were used to determine the extent and organisation of neocortical projections from the suprageniculate (SG) and posterior (PO) thalamic nuclei in the brush-tailed possum. Our findings show that SG projects extensively to the auditory cortex, overlapping the cortical projection field of the medial geniculate nucleus, and to the immediately neighbouring association cortex. Though the input relationships of SG appear similar to those reported for other mammals, placental and marsupial, a strong SG projection to auditory cortex has not been reported previously. Neocortical relationships of PO are characterised by an orderly point-to-point projection to all but the most rostral parts of the motor-somaesthetic cortex. There is also a substantial projection to the entire posterior parietal association cortex. The PO-neocortex projection is reciprocally organised. The PO-neocortical projection in the possum is similar to that reported in the Virginia opossum, rat, and several other mammals. There is a major difference in organisation in comparison with certain monkeys where the PO projection is much more restricted and does not involve the motor and somaesthetic cortex. We conclude that PO is similarly organised in many, though not all, mammals, including the marsupials, rodents, insectivores, and prosimian primates. The possum SG, on the other hand, is clearly distinct from other mammals in its extensive projection to auditory cortex, though we cannot say at present whether this a general property of marsupial mammals or a peculiarity restricted to this species and possibly its close relatives.

Animals↗
PubMed2003

Functional-adaptive anatomy of the axial skeleton of some extant marsupials and the paleobiology of the paleocene marsupials Mayulestes ferox and Pucadelphys andinus.

In this study, the axial skeletons of two Early Paleocene marsupials, Mayulestes ferox and Pucadelphys andinus, were analyzed functionally and compared to that of six South American and three Australian species of extant marsupials. In the case of the South American opossums, myological data of the epaxial musculature were collected and analyzed and osteological-myological associations were related to locomotor behavior. Various features of the vertebral column that relate to diet or to locomotor or postural patterns were pointed out. These features include: the craniocaudal development of the neural process of the axis; the position of the anticlinal vertebra; the morphology of the neural processes of the thoracolumbar vertebrae (orientation, length, and craniocaudal width); the length, orientation, and curvature of the transverse processes of the lumbar vertebrae; and the length and robustness of the caudal vertebrae. In both fossil forms the vertebral column is mobile and allows a great range of flexion and extension of the spine, more so than in most of the living didelphids. It is emphasized here that the analysis of the axial skeleton complements and improves the conclusions provided by the forelimb and hindlimb analyses. It is proposed that Mayulestes and Pucadelphys represent an ancestral morphotype suggesting that the generalized type of locomotion of Paleocene marsupials was partly terrestrial with some climbing ability.

Adaptation, Physiological↗
PubMed1999

Comparative chromosome painting between marsupial orders: relationships with a 2n = 14 ancestral marsupial karyotype.

A 2n = 14 karyotype is shared by some species in each of the marsupial orders in Australian and American superfamilies, suggesting that the ancestral marsupial chromosome complement was 2n = 14. We have used chromosome painting between distantly related marsupial species to discover whether genome arrangements in 2n = 14 species in two Australian orders support this hypothesis. Cross-species chromosome painting was used to investigate chromosome rearrangements between a macropodid species Macropus eugenii (2n = 16) and a wombat species in a different suborder (Lasiorhinus latifrons, 2n = 14), and a dasyurid species in a different order (Sminthopsis macroura, 2n = 14). We demonstrate that many chromosome regions are conserved between all three species, and deduce how the similar 2n = 14 karyotypes of species in the two orders are related to a common ancestral 2n = 14 karyotype.

Animals↗
PubMed2002

Functional-adaptive analysis of the hindlimb anatomy of extant marsupials and the paleobiology of the Paleocene marsupials Mayulestes ferox and Pucadelphys andinus.

This article analyzes the adaptations of the hindlimb of two Early Paleocene marsupials, Mayulestes ferox and Pucadelphys andinus. This analysis is based on detailed comparisons with various extant marsupials, both South American and Australian. In the case of the South American opossums, original myological data were collected and osteological-myological associations were related to their locomotor behavior. The use of Australian genera helped to improve the appraisal of the locomotory habits of the fossil taxa. Several features are indicative of the ability of Mayulestes to climb or walk on uneven surfaces (e.g., very mobile hip joint, astragalocalcaneal joint pattern), and some other features emphasize a relative agility (e.g., strongly everted iliac blades, morphology of the distal epiphysis of the femur, medially stabilized cruroastragalar joint). Pucadelphys exhibits a hindlimb relatively similar morphologically to that of Mayulestes, but with features indicating slightly increased agility and a terrestrial component that is more emphasized than in Mayulestes. The Tiupampa fossils were therefore more agile than most living didelphids and resembled the condition observed in living dasyurids more. These conclusions complement a previous study performed on the forelimb of these fossils.

Animals↗
PubMed1988

Sex determination in marsupials: evidence for a marsupial-eutherian dichotomy.

In this paper, we review briefly the current state of knowledge about sexual differentiation in eutherian mammals, and then describe the situation in detail in two marsupial species: the North American opossum and the tammar wallaby. The conventional explanation for the genesis of all male somatic sexual dimorphisms in mammals is that they are a consequence of the systemic action of testicular hormones. In the absence of testes, the embryo will develop a female phenotype. We present evidence for the tammar wallaby that calls into question the universal applicability of this hormonal theory of mammalian sexual differentiation. We have shown that extensive somatic sexual dimorphisms precede by many days the first morphological evidence of testicular formation, which does not occur until around the third day of pouch life. Male foetuses, and pouch young on the day of birth, already have a well-developed gubernaculum and processus vaginalis, paired scrotal anlagen, and a complete absence of mammary anlagen, whereas female foetuses and newborn pouch young have a poorly developed gubernaculum and processus vaginalis, no scrotal anlagen, and well-developed mammary anlagen. Because it seems unlikely that the male gonad could begin hormone secretion until after the Sertoli and Leydig cells are developed, our results strongly suggest that some sexually dimorphic somatic characteristics develop autonomously, depending on their genotype rather than the hormonal environment to which they are exposed. We have been able to confirm the hormonal independence of the scrotum, pouch and mammary gland by administering testosterone propionate daily by mouth to female pouch young from the day of birth; although the Wolffian duct was hyperstimulated, there was no sign of scrotal development, or pouch or mammary inhibition. When male pouch young were treated with oestradiol benzoate in a similar fashion, there was hyperstimulation of the Müllerian duct and inhibition of testicular migration and development, but no sign of scrotal inhibition or pouch or mammary development. Our results in the tammar wallaby are consistent with the earlier studies on the opossum, whose significance was not appreciated at the time. Further evidence in support of this hormonal independence comes from earlier studies of spontaneously occurring intersexes in several species of marsupial, including the opossum and the tammar wallaby. An XXY individual had intra-abdominal testes and complete masculinization of the male reproductive tract internally, but externally there was a pouch and mammary glands and no scrotum.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

[Closed marsupialization and delayed marsupialization in the treatment of severe pancreatitis].

The timing for surgical intervention and the type of operation in the treatment of severe pancreatitis are still controversial. In this study, we used closed marsupialization in which early operation was preferable and after decompression of the pancreas and necrosectomy, both edges of the opened greater omentum were sutured respectively to the upper and lower peritoneal borders of the transverse abdominal incision, forming a marsupium separating the greater and lesser abdominal cavities from each other. The abdominal incision was then sutured to close the opening of the marsupium. Should clinical features or CT, BUS scan have indicated the existence of pancreatic abscess a week or longer after the exploration, stiches of the abdominal wall incision were removed. The marsupium was easily reentered and necrotic tissue removed. As the omentum edges were adhered to the abdominal wall incision separating the greater and lesser abdominal cavities, reoperation was safe. The incision was then kept open (delayed marsupialization). The theoretical basis of the operation and satisfactory clinical results are discussed.

Acute Disease↗
PubMed1978

The use of marsupial x eutherian somatic cell hybrids to study marsupial cell surface antigens.

Buck and Bodmer (1976) have developed a technique for identifying an antigen on the surface of human x mouse somatic cell hybrids, specified by a gene on a particular human chromosome. We have successfully adapted this technique to a study of marsupial cell surface antigens. Somatic cell hybrids between Macropus rufus (Marsupialia) lymphocytes and the mouse cell lines PG19 and 1R were injected intraperitoneally into mice of the same inbred strain from which the above cell lines were derived (C57B16J and C3H, respectively). The only identified M. rufus chromosome present in the hybrid cells was the X chromosome. The antisera, after adsorption with PG19 or 1R, were tested using indirect immunofluorescence, against the hybrid cells, and also against sub-clones (derived from hybrids) which had apparently lost the M. rufus X chromosome, or at least its long arm. The results of these tests showed that the absorbed antisera contained reactivity against an M. rufus cell surface antigen (or antigens). The reactions of one of the antisera were most simply interpreted by supposing that it was detecting an M. rufus X-lined antigen(s).

Animals↗
PubMed2002

Mapping the distribution of the interstitial telomeric (TTAGGG)n sequences in eight species of Brazilian marsupials (Didelphidae) by FISH and the correlation with constitutive heterochromatin. Do ITS represent evidence for fusion events in American marsupials?

The C-band pattern and the distribution of the (TTAGGG)(n) sequence after fluorescence in situ hybridization (FISH), were studied in eight species of Didelphidae marsupials: four species with 2n = 14 (Marmosops parvidens, Marmosops incanus, Marmosa murina and Metachirus nudicaudatus), two species with 2n = 18 (Monodelphis domestica and M. americana), and two with 2n = 22 (Didelphis marsupialis and Lutreolina crassicaudata). The hybridization signals were observed at both termini telomeres of all chromosomes. In addition, interstitial sequences were detected in the pericentromeric region of all chromosomes of Marmosops parvidens, in five chromosome pairs of M. incanus, and in the first pair of Monodelphis domestica. These sites always occur in the region of constitutive heterochromatin, even though C-band positive regions do not always present interstitial telomeric sequences (ITS). We suggest that the interstitial (TTAGGG)(n) sequences are associated with satellite DNA and do not necessarily arise through chromosomal rearrangements.

Animals↗
PubMed1991

Bile acids of marsupials. 2. Hepatic formation of vulpecholic acid (1 alpha,3 alpha,7 alpha-trihydroxy-5 beta-cholan-24-oic acid) from chenodeoxycholic acid in a marsupial, Trichosurus vulpecula (Lesson).

Free vulpecholic acid (1 alpha,3 alpha,7 alpha-trihydroxy-5 beta-cholan-24-oic) is the major biliary component of the Australian opossum (Trichosurus vulpecula), accompanied only by a few percent of its taurine conjugate. In order to exclude a microbial involvement in its formation (i.e., secondary origin) four sets of experiments were performed. It was found that a) the level of vulpecholic acid remained unchanged in the bile of opossums fed with neomycin and kanamycin for 7 days prior to bile collection; b) it also remained unchanged after long bile drainage; c) in opossums prepared with biliary cannula, intraportally injected [24-14C]chenodeoxycholic acid was transformed to [24-14C]vulpecholic acid; and d) in a similar experiment, the detectable transformation of [1 alpha,2 alpha-3H2]cholesterol to vulpecholic acid was observed. In experiment c) 28-66% of the administered radioactivity was secreted in 2 h in the form of free biliary vulpecholic and chenodeoxycholic acids. Only a trace amount of the corresponding taurine conjugates (approximately 0.4%) was formed. Moreover, rapidly declining specific radioactivity of the unconjugated chenodeoxycholic acid indicated its probable participation in the native formation of vulpecholic acid.

Animals↗