Use of time and space by platypus (Ornithorhynchus anatinus: Monotremata) along a Victorian stream

Radio-tracking and mark recapture methods were used to characterize the spatial organization and temporal activity patterns of free-ranging platypuses in southern Victoria. The study area supported an estimated 1.3-2.1 adult or subadult animals per kilometre of stream in the three summers sampled. The individual home ranges of 15 radio-tagged animals comprised 0.33-2.28 km of stream; animals foraging exclusively in the stream had significantly longer ranges (mean=1.40 km) than animals which also foraged in associated pond habitats (mean=0.64km). Home ranges of grown females overlapped with those of neighbouring grown females, subadult and adult males, and juveniles (相似文献   

Circadian Activity Rhythms in the Australian Platypus, Ornithorhynchus anatinus (Monotremata)

The Australian platypus, Ornithorhynchus anatinus, is one of three extant genera of the order monotremata. Given the divergent evolutionary lineage of monotremes in relation to more commonly studied animals, it was of interest to determine first, whether platypuses possess endogenous biological pacemakers and, second, general parameters of aquatic activity rhythms under artificial and natural light-dark (LD) cycles. Using a novel recording device, aquatic activity rhythms were measured in three platypuses: a paired male and female studied together, and a single female studied in isolation from other platypuses. Under a constant photic environment, some evidence was found for persistent and free-running rhythmicity, indicating the presence of an endogenous circadian pacemaker in the platypus. Under artificial LD cycles the paired animals exhibited a nocturnal pattern of entrainment, although in the single female considerable variability in entrained phase-relations was found under natural LD cycles. Evidence for a circadian pacemaker in the hypothalamic region of platypuses is also discussed.     

Circadian Activity Rhythms in the Australian Platypus,Ornithorhynchus anatinus (Monotremata)

The Australian platypus, Ornithorhynchus anatinus, is one of three extant genera of the order monotremata. Given the divergent evolutionary lineage of monotremes in relation to more commonly studied animals, it was of interest to determine first, whether platypuses possess endogenous biological pacemakers and, second, general parameters of aquatic activity rhythms under artificial and natural light–dark (LD) cycles. Using a novel recording device, aquatic activity rhythms were measured in three platypuses: a paired male and female studied together, and a single female studied in isolation from other platypuses. Under a constant photic environment, some evidence was found for persistent and free-running rhythmicity, indicating the presence of an endogenous circadian pacemaker in the platypus. Under artificial LD cycles the paired animals exhibited a nocturnal pattern of entrainment, although in the single female considerable variability in entrained phase-relations was found under natural LD cycles. Evidence for a circadian pacemaker in the hypothalamic region of platypuses is also discussed.     

Energetics of foraging and locomotion in the platypus Ornithorhynchus anatinus

We measured the energy requirements of platypuses foraging, diving and resting in a swim tank using flow-through respirometry. Also, walking metabolic rates were obtained from platypuses walking on a conventional treadmill. Energy requirements while foraging were found to depend on water temperature, body weight and dive duration and averaged 8.48 W kg(-1). Rates for subsurface swimming averaged 6.71 W kg(-1). Minimal cost of transport for subsurface swimming platypuses was 1.85 J N(-1)m(-1) at a speed of 0.4 m s(-1). Aerobic dive limit of the platypus amounted to 59 s. Metabolic rate of platypuses resting on the water surface was minimal with 3.91 W kg(-1) while minimal RMR on land was 2.08 W kg(-1). The metabolic rate for walking was 8.80 W kg(-1) and 10.56 W kg(-1) at speeds of 0.2 m s(-1) and 0.3 m s(-1), respectively. A formula was derived, which allows prediction of power requirements of platypuses in the wild from measurements of body weight, dive duration and water temperature. Platypuses were found to expend energy at only half the rate of semiaquatic eutherians of comparable body sizes during both walking and diving. However, costs of transport at optimal speed were in line with findings for eutherians. These patterns suggest that underwater locomotion of semiaquatic mammals have converged on very similar efficiencies despite differences in phylogeny and locomotor mode.     

Immunoglobulin genetics of Ornithorhynchus anatinus (platypus) and Tachyglossus aculeatus (short-beaked echidna)

In this paper, we review data on the monotreme immune system focusing on the characterisation of lymphoid tissue and of antibody responses, as well the recent cloning of immunoglobulin genes. It is now known that monotremes utilise immunoglobulin isotypes that are structurally identical to those found in marsupials and eutherians, but which differ to those found in birds and reptiles. Monotremes utilise IgM, IgG, IgA and IgE. They do not use IgY. Their IgG and IgA constant regions contain three domains plus a hinge region. Preliminary analysis of monotreme heavy chain variable region diversity suggests that the platypus primarily uses a single VH clan, while the short-beaked echidna utilises at least 4 distinct VH families which segregate into all three mammalian VH clans. Phylogenetic analysis of the immunoglobulin heavy chain constant region gene sequences provides strong support for the Theria hypothesis. The constant region of IgM has proven to be a useful marker for estimating the time of divergence of mammalian lineages.     

Theileria ornithorhynchi Mackerras, 1959 in the platypus, Ornithorhynchus anatinus (Shaw)

Blood smears from 54 platypuses in southeastern Australia were examined by light microscopy. Protozoa were found in erythrocytes in 53 platypuses; all infections were sparse. A few parasites were found in leukocytes. Intraerythrocytic forms examined by electron microscopy contained vacuoles, micronemes, rhoptries and cytostomes with double unit membranes. Merozoites were identified in leukocytes. The parasites were identified as Theileria ornithorhynchi Mackerras, 1959.     

Two monotreme cell lines,derived from female platypuses (Ornithorhynchus anatinus; Monotremata,mammalia)

Summary Two diploid platypus cell lines, designated Oa-1F and Oa-2F, have been derived from the toe webs of two females. The development and growth characteristics of the lines are described and G-banded karyotypes presented (the first reported for the platypus). The availability of these lines will greatly facilitate chromosome and gene mapping studies of the platypus and permit the extension of comparative studies of mammalian chromosome and genome evolution to the monotremes.     

Ten polymorphic microsatellite DNA markers for the platypus, Ornithorhynchus anatinus

We identified and optimized 10 microsatellite loci for the platypus, Ornithorhynchus anatinus (Monotremata: Ornithorhynchidae), and screened 21 individuals from the southern tablelands area of New South Wales, Australia. Each polymorphic locus possessed between two and 12 alleles with observed heterozygosities between 0.118 and 0.950. The intent of this effort was to provide informative loci for studies on the population genetics of this species.     

Lesions associated with metazoan parasites of wild platypuses (Ornithorhynchus anatinus)

Pathological findings associated with helminth and arthropod parasites of four wild platypuses (Ornithorhynchus anatinus) are described. Fourth-stage larval rhabditoid nematodes (?Cylindrocorporidae) found partially embedded in the stratum corneum were associated with mild acanthosis, orthokeratotic hyperkeratosis and inconstant subacute dermatits. A filarioid nematode (?Lemdaninae) was found in hypodermal lymphoid tissue. A larval trichostrongyloid nematode was found in the dermis, with no evidence of host response. An undescribed species of trombiculid mite ("chigger") was found in the pelage and attached to superficial stratum corneum. Focal inclusions of eosinophilic material within stratum corneum, interpreted as mite gel saliva produced during formation of the "stylostome," were also observed. The tick Ixodes ornithorhynchi punctured the epidermis causing adnexal trauma, dermal haemorrhage and chronic active dermatitis. The digenean Mehlisia ornithorhynchi was present in the small intestine of one animal and was associated with mild catarrhal enteritis.     

Iron(III) binding proteins of echidna (Tachyglossus aculeatus) and platypus (Ornithorhynchus anatinus)

Iron (III) binding proteins are isolated from echidna (Tachyglossus aculeatus multiaculeatus) and platypus (Ornithorhynchus anatinus) milk and blood. On the basis of several criteria it is shown that the milk proteins are not lactoferrins, but are transferrins similar to the corresponding transferrins from the blood. The heterogeneity of the proteins, particularly the echidna milk transferrin, is, at least in part, due to different levels of sialic acid. Their N-terminal sequences (30 residues) are determined and compared with those of other transferrins and lactoferrins. The role of the proteins is discussed.     

A viral infection causing cytomegalic inclusion disease in the renal epithelium of the platypus (Ornithorhynchus anatinus)

Cytomegaly and intranuclear inclusion bodies were observed in the renal collecting duct epithelium in three of four wild caught platypuses (Ornithorhynchus anatinus) from New South Wales using light and electron microscopy during routine pathological studies. Non-enveloped, spherical virions measuring about 80 nm in diameter were present in the nucleus and cytoplasm of affected cells as well as in the lumen of the renal tubule. A single enveloped virion measuring about 150 nm in diameter was found. There was no serological evidence of infection with cytomegalovirus (AD169 antigen) or adenovirus (mammalian and avian group antigens) in any of the platypuses. Although the identity of the virus was not confirmed, it was probably an adenovirus based on morphological grounds. The infection appeared to have little effect on the host.     

The neurohypophysial hormones of the egg-laying mammals: identification of arginine vasopressin in the platypus (Ornithorhynchus anatinus)

Two neurohypophysial peptides have been purified from acetone desiccated posterior pituitary glands of the platypus (Ornithorhynchus anatinus) by molecular sieving and high-pressure liquid chromatography. A single pressor peptide, having an amino acid composition and a chromatographic retention time identical to those of arginine vasopressin, has been identified. A single oxytocic peptide has been isolated that ressembles oxytocin by its chromatographic retention time, but lack of material has prevented to obtain a correct amino acid composition. The pressor peptide is roughly four times more abundant than the oxytocic peptide. Neurohypophysial hormones of platypus seem similar to those of echidna, the other living prototherian, and to those of most placental mammals.     

Diversity at the major histocompatibility complex Class II in the platypus, Ornithorhynchus anatinus

The platypus (Ornithorhynchus anatinus) is the sole survivor of a previously widely distributed and diverse lineage of ornithorhynchid monotremes. Its dependence on healthy water systems imposes an inherent sensitivity to habitat degradation and climate change. Here, we compare genetic diversity at the major histocompatibility complex (MHC) Class II-DZB gene and 3 MHC-associated microsatellite markers with diversity at 6 neutral microsatellite markers in 70 platypuses from across their range, including the mainland of Australia and the isolated populations of Tasmania, King Island, and Kangaroo Island. Overall, high DZB diversity was observed in the platypus, with 57 DZB β1 alleles characterized. Significant positive selection was detected within the DZB peptide-binding region, promoting variation in this domain. Low levels of genetic diversity were detected at all markers in the 2 island populations, King Island (endemic) and Kangaroo Island (introduced), with the King Island platypuses monomorphic at the DZB locus. Loss of MHC diversity on King Island is of concern, as the population may have compromised immunological fitness and reduced ability to resist changing environmental conditions.     

Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus

We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural aerobic dive limit (ADL) of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Individual platypuses were equipped with combined data logger-transmitter packages measuring dive depth. Mean dive duration was 31.3 s with 72% of all dives lasting between 18 and 40 s. Mean surface duration was 10.1 s. Mean dive depth was 1.28 m with a maximum of 8.77 m. Platypuses performed up to 1600 dives per foraging trip with a mean of 75 dives per hour. ADL was estimated by consideration of post-dive surface intervals vs. dive durations. Only 15% of all dives were found to exceed the estimated ADL of 40 s, indicating mainly aerobic diving in the species. Foraging platypuses followed a model of optimised recovery time, the optimal breathing theory. Total bottom duration or total foraging duration per day is proposed as a useful indicator of foraging efficiency and hence habitat quality in the species.     

Splenic hemopoiesis of the platypus (Ornithorhynchus anatinus): evidence of primary hemopoiesis in the spleen of a primitive mammal

The generation of blood cells has been observed in the spleen and in the bone marrow of the platypus. Hemopoiesis was found to be far more active in the spleen than in the bone marrow judging by the number of proliferating hemopoietic elements within a unit area of tissue from each organ. Granulocytes, erythroblasts, and megakaryocytes, with the related immature forms for each cell line, were noted in the spleen. In contrast, there were very few examples of immature forms of these cell lines and a complete absence of mature megakaryocytes in the bone marrow. These findings suggest that the spleen is the primary hemopoietic organ in the platypus. Since the platypus is one of two species representing the most primitive existing mammals, it seems likely that the spleen may be the primary hemopoietic organ in mammalian evolution.