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At least 19 recordsLinked to original sources
PubMed1979

The anoplocephalid cestode parasites of the spectacled hare-wallaby Lagorchestes conspicillatus Gould, 1842 (Marsupialia: Macropodidae).

Progamotaenia gynandrolinearis sp. nov. is described from the small intestine of Lagorchestes conspicillatus Gould, 1842 from Barrow I., Western Australia. It is distinguished from other species by the small number of testes arranged in a single transverse row. Progamotaenia lagorchestis (Lewis, 1914) is redescribed. The name Progamotaenia thylogale sp. nov. is proposed for a second species described previously under the name P. lagorchestis. Progamotaenia zschokkei (Janicki, 1905), Progamotaenia festiva (Rudolphi, 1819) and Progamotaenia villosa (Lewis, 1914) were also found in L. conspicillatus.

Animals↗
PubMed1978

Hormonal control of embryonic diapause and reactivation in the tammar wallaby.

Suckling is the most important and best-known influence that the marsupia offspring exerts on its mother but recent evidence suggests that this is not the only way it proclaims its presence. The pregnant female differs from the non-pregnant in several features, which appear to be due to the presence of the conceptus in the uterus. The converse influence of the female on the embryo is best known in kangaroos and wallabies because the facultative and obligate embryonic diapause they exhibit has provided excellent opportunities for experimental investigation of the environmental and hormonal control of early pregnancy. Results from the tammar wallaby, which exhibits both types of diapause, show that the initiation of diapause occurs on Day 8 p.c. The sequence of events that lead to blastocyst reactivation, after removing the suckling stimulus (facultative diapause), takes seven days and involves a reduction in prolactin secretion from the anterior pituitary, reactivation of the corpus luteum, increase in endometrial secretion and reactivation of the blastocyst. The ultimate control of obligate diapause involves alteration of photoperiod but the role of prolactin is still uncertain.

Animals↗
PubMed1979

Observations of the pineal region of non-eutherian mammals.

A survey has been made of the pineal region of the brain of 11 species of marsupials belonging to 5 families and a species from both families of monotremes. The results show that the pineal body of non-eutherian mammals, although well-defined in all species, has a very varied morphology. Three types of pineal recess occur: (i) a pineal recess in sensu stricto, (ii) an intercommissural pineal recess, and (iii) an infrapineal recess. The existence of nerve fibres which pass through the pineal body and form a spatial link between the habenular and posterior commissures, has been demonstrated in marsupials and monotremes. It is also likely that these animals as well as eutherian mammals possess a nervus conarii. Nerve cells are not a constant feature of the non-eutherian pineal body. The subcommissural organ (SCO) is present in all species. It does not exhibit the same degree of morphological variation as the pineal body. Horizontal sections available for 4 species within 3 families of marsupials show it to be composed of a median portion jointed to bilateral protuberances. Large nerve cells occur within the SCO in all marsupial species; they are absent from the monotreme SCO. Tentatively, the relationship of these neurons to the SCO is considered to be merely one of association. The importance of an extended comparative study of this region in non-eutherian mammals in order to add insight into its phylogeny and function is emphasized.

Animals↗
PubMed1979

Genetic microsurgery by laser: establishment of a clonal population of rat kangaroo cells (PTK2) with a directed deficiency in a chromosomal nucleolar organizer.

An ultraviolet laser beam was focused to a submicron spot on one of the nucleolar organizer regions of mitotic chromosomes of rat kangaroo cells in tissue culture. The daughter cells were isolated and cloned into a viable population that maintained the directed nucleolar deficiency. It is concluded that the laser can be used to delete preselected genetic regions and the genetic deletion is maintained as a heritable deficiency in subsequent daughter cells.

Animals↗
PubMed1975

Visualization of nucleolar organizer regions im mammalian chromosomes using silver staining.

A simple ammoniacal silver staining procedure, designated Ag-AS, differentially stains the chromosomal locations of ribosomal DNA in certain mammalian species. This was critically demonstrated by Ag-AS staining of the nucleolus organizer regions in karyotypes of the same species and cell lines used for locating the ribosomal cistrons by DNA/RNA in situ hybridization. With Ag-AS, silver stained NORs (Ag-NORs) are visualized as black spherical bodies on yellow-brown chromosome arms. Ag-NORs were visualized throughout mitosis at the secondary constrictions in the rat kangaroo, Seba's fruit bat, Indian muntjac, and Rhesus monkey. The Chinese hamster and cattle have telomeric Ag-NORs, the mouse subcentromeric Ag-NORs, and the field vole Ag-NORs as minute short arms or choromosomal satellites. Ag-NORs occur at both secondary constrictions and at telomeres in the cotton rat. Variability in Ag-NOR pattern included differences in the number of Ag-NORs per cell within a cell population, size of Ag-NORs among chromosomes of a complement, and presence of Ag-NOR on particular chromosomes in two cell lines of the Chinese hamster. The available cytochemical data suggest that the Ag-AS reaction stains chromosomal proteins at the NOR rather than the rDNA itself.

Animals↗
PubMed1979

Preferential occurrence of sister chromatid exchanges at heterochromatin-euchromatin junctions in the wallaby and hamster chromosomes.

Chromosomes of two mammalian species, the white-throated wallaby and the rat-like hamster, possessed large amounts of constitutive heterochromatin which is detectable as C bands. By making use of this character the frequency of sister chromatid exchanges (SCEs) was determined for the C band and the euchromatic regions of the chromosome. In both species, the distribution of SCEs in the euchromatin of chromosomes was found to be proportional to its metaphase length, while the number of SCEs localized in the C band regions was clearly fewer than expected on the basis of the relative length of those regions at metaphase. Many SCE's were, however, detected at the junctions between the euchromatin and the C band heterochromatin. All of these findings were consistent with previous observations on the Indian muntjac and the kangaroo rat chromosomes.

Animals↗
PubMed1979

A histochemical study of denervated marsupial hemidiaphragm.

The marsupial (quokka) hemidiaphragm showed postdenervation hypertrophy and subsequent atrophy. The type II muscle fibres hypertrophied up to 20 days postoperation and then regressed. However, the type I fibres hypertrophied throughout the experimental period (100 days) studied. Unlike denervated eutherian hemidiaphragm, fibre-splitting was absent in the denervated marsupial muscle. An enhancement of the ATPase reaction in the denervated type I fibres may be due to dedifferentiation. Presumably innervation exerts a 'negative control' and prevents increase of type I fibre size in the normal hemidiaphragm.

Adenosine Triphosphatases↗
PubMed1979

Ocular toxoplasmosis in wallabies (Macropus rufogriseus).

We initiated a pathologic investigation of ocular disease in wallabies. Of 21 animals examined, the eyes were investigated histologically in 11; in four of these animals the brains were also available for section and the sera were investigated in three. In ten animals only sera were received. Histologic studies showed bilateral or unilateral cataract in five animals. Eight animals, with or without cataracts, showed various degrees of keratitis, uveitis, choroidoretinitis, or endophthalmitis. In three animals Toxoplasma cysts were found within the retina or brain, or both. Of the 13 cases examined serologically 11 were positive for toxoplasmosis; three reached high titers.

Animals↗
PubMed1975

In vivo and in vitro aging of collagen examined using an isometric melting technique.

1. In vivo and in vitro aging of tendon from rat tail, kangaroo tail and human wrist tendon was examined by the technique of isometric melting, in physiological saline. 2. For all these collagens, two mechanisms of structure stabilisation can be distinguished in the melting curves. One of these involves co-valent cross-linking as judged by its increasing stability to heat and acid pH, while the second appears to involve only secondary interactions. 3. The time rate of the first process is slow in vivo; rat tendon up to 2 years does not show it, but it is present in 6-year-old human tendon. However, its in vitro rate is markedly dependent upon the free oxygen content of the physiological saline. At an oxygen concentration of 300 nmol/ml, the in vitro aging rate is about 30 times the in vivo rate for rat tail tendon, and about 20 times for both kangaroo tail tendon and human wrist tendon. At a concentration of 60 nmol/ml (which is about the same as normal arteriovenous blood difference) in vitro aging proceeds close to the in vivo rate.

Age Factors↗