Neuronal inclusions resembling Negri bodies in the thalamus of a red kangaroo (Macropus rufus).

Eosinophilic intracytoplasmic neuronal inclusions resembling Negri bodies, but not associated with lyssaviral infection, were detected in the ventrolateral thalamus of a young-adult, male red kangaroo (Macropus rufus). Similar neuronal inclusions, also with a regional distribution in the brain, have been reported as an incidental, possibly age-related finding in other animal species.

Extinction of eastern Sahul megafauna coincides with sustained environmental deterioration.

Explanations for the Upper Pleistocene extinction of megafauna from Sahul (Australia and New Guinea) remain unresolved. Extinction hypotheses have advanced climate or human-driven scenarios, in spite of over three quarters of Sahul lacking reliable biogeographic or chronologic data. Here we present new megafauna from north-eastern Australia that suffered extinction sometime after 40,100 (±1700) years ago. Megafauna fossils preserved alongside leaves, seeds, pollen and insects, indicate a sclerophyllous forest with heathy understorey that was home to aquatic and terrestrial carnivorous reptiles and megaherbivores, including the world's largest kangaroo. Megafauna species diversity is greater compared to southern sites of similar age, which is contrary to expectations if extinctions followed proposed migration routes for people across Sahul. Our results do not support rapid or synchronous human-mediated continental-wide extinction, or the proposed timing of peak extinction events. Instead, megafauna extinctions coincide with regionally staggered spatio-temporal deterioration in hydroclimate coupled with sustained environmental change.

Plant poisoning leads to alpha-synucleinopathy and neuromelanopathy in kangaroos.

The pathogenesis of synucleinopathies, common neuropathological lesions normally associated with some human neurodegenerative disorders such as Parkinson's disease, dementia with Lewy bodies and multiple system atrophy, remains poorly understood. In animals, ingestion of the tryptamine-alkaloid-rich phalaris pastures plants causes a disorder called Phalaris staggers, a neurological syndrome reported in kangaroos. The aim of the study was to characterise the clinical and neuropathological changes associated with spontaneous cases of Phalaris staggers in kangaroos. Gross, histological, ultrastructural and Immunohistochemical studies were performed to demonstrate neuronal accumulation of neuromelanin and aggregated α-synuclein. ELISA and mass spectrometry were used to detect serum-borne α-synuclein and tryptamine alkaloids respectively. We report that neurons in the central and enteric nervous systems of affected kangaroos display extensive accumulation of neuromelanin in the perikaryon without affecting neuronal morphology. Ultrastructural studies confirmed the typical structure of neuromelanin. While we demonstrated strong staining of α-synuclein, restricted to neurons, intracytoplasmic Lewy bodies inclusions were not observed. α-synuclein aggregates levels were shown to be lower in sera of the affected kangaroos compared to unaffected herd mate kangaroos. Finally, mass spectrometry failed to detect the alkaloid toxins in the sera derived from the affected kangaroos. Our preliminary findings warrant further investigation of Phalaris staggers in kangaroos, potentially a valuable large animal model for environmentally-acquired toxic synucleinopathy.

Guiding Development of the Neonate: Lessons from Mammalia.

Significantly preterm and low-birthweight (LBW) babies have diminished lung and gut development, generally fail to thrive, have increased mortality and higher frequency of mature-onset disease. Mothers often cannot breastfeed, and babies receive either formula or pasteurized donor milk, which may further limit the baby's recovery. New approaches are required to manage the early stages of neonatal development. The tammar wallaby, an Australian marsupial, has a short gestation and a simple placenta, and gives birth to an altricial young equivalent to a final trimester human embryo. The neonate remains in the pouch and attached to the teat for 100 days postpartum. The mother slows growth of the young and progressively changes the composition of the milk to deliver signals for organ development, including the lung and gut. This closely resembles the relationship between the human fetus and delivery of placental and uterine bioactives. Datasets comprised of differentially expressed genes coding for secreted proteins in early lactation in the tammar mammary gland have been compared to databases produced from human placenta, amniotic fluid, colostrum and milk to identify human homologues for the putative signaling molecules for organ development. These data will be used to develop milk fortifiers for treatment of preterm and LBW babies in both the developed and the developing world.

Controversial cuisine: A global account of the demand, supply and acceptance of "unconventional" and "exotic" meats.

In most societies, meat is more highly prized, yet more frequently tabooed, than any other food. The reasons for these taboos are complex and their origins have been the focus of considerable research. In this paper, we illustrate this complexity by deliberating on several "unconventional" or "exotic" animals that are eaten around the world, but whose consumption evokes strong emotions, controversy and even national discourse: dogs, equids, kangaroos, marine mammals, primates, rodents and reptiles. We take a systematic approach, reflecting on the historical and current demand for the meat, the manner in which this demand is met, and how individual and societal attitudes towards these species shape their approval as food. What emerges from this synthesis is that conflicting views on the aforementioned species exist not only between Western societies and elsewhere, but also in nations where these animals are readily consumed. Moreover, such taboos are seldom based on functionalist explanations alone, but rather have overwhelming symbolic and psychological groundings.

Effects of nutritional manipulation on body composition in the developing marsupial, Macropus eugenii.

When 60-day-old tammar wallaby pouch young (Macropus eugenii) are fostered to mothers at 120 days of lactation, their growth, developmental rate and maturation of their GH/IGF axes are markedly accelerated. To determine the effect of fostering on energy intake, body composition and fat accretion, we first measured total body fat and lean mass in these young. Next, we mimicked the triglyceride oleic and palmitic acid composition of 120-day milk by supplementing 60 day young with these fatty acids and comparing their growth with that of growth accelerated young. There was no difference in the weight or growth axis maturation of supplemented young but there was significantly more body fat in these and in the growth-accelerated fostered young than in controls. We conclude that the accelerated growth and GH/IGF axis maturation observed previously in fostered young is most likely due to increased milk consumption and earlier access to specific nutrients.

Expression of the mammary gland-specific tammar wallaby early lactation protein gene is maintained in vitro in the absence of prolactin.

Marsupial ELP (early lactation protein) and its eutherian orthologue, CTI (colostrum trypsin inhibitor) are expressed in the mammary gland only for the first 100 days postpartum (Phase 2A) in the tammar wallaby and during the bovine and canine colostrogenesis period 24-36h postpartum respectively. The factors which regulate temporal ELP and CTI expression are unknown. A tammar mammary gland explant culture model was used to investigate ELP gene regulation during pregnancy and early- and mid-lactation (Phase 1, 2A and 2B respectively). Tammar ELP expression could only be manipulated in explants in vitro if the gene was already expressed in vivo. ELP expression was maximal in Phase 1 explants treated with lactogenic hormones (insulin, hydrocortisone and prolactin), but unlike LGB (ß-lactoglobulin), ELP expression was maintained in insulin or insulin and hydrocortisone over a 12-day culture period. In contrast, ELP was down-regulated when cultured without hormones. ELP could not be induced in explants cultured from mid-lactation which suggested that transcriptional repressors may prevent ELP expression during this period.

Integrative Review of Nursing Intervention Studies on Mother-Infant Interactions

PURPOSE: The purpose of this study was to describe the components and content of nursing intervention studies on mother-infant interactions and to present strategies for future studies. METHODS: Four electronic databases in the Korean language were searched to identify studies done between January 1998 and December 2011. The search yielded 145 articles. From these articles, 19 studies met the inclusion criteria. RESULTS: Mother-infant interactions in these studies were found to include verbal and non-verbal communication basic for optimal growth and development of the child. Six kinds of interventions for mother-infant interactions were identified as follows: sensory stimulation, education program, whole body massage, kangaroo care, visiting support, and music therapy. CONCLUSION: Further studies with well designed clinical trials need to be done in the area of child nursing to provide evidence based data for the development of strategies to promote positive mother-infant interactions.

Unintended consequences of invasive predator control in an Australian forest: overabundant wallabies and vegetation change.

Over-abundance of native herbivores is a problem in many forests worldwide. The abundance of native macropod wallabies is extremely high at Booderee National Park (BNP) in south-eastern Australia. This has occurred because of the reduction of exotic predators through an intensive baiting program, coupled with the absence of other predators. The high density of wallabies at BNP may be inhibiting the recruitment of many plant species following fire-induced recruitment events. We experimentally examined the post-fire response of a range of plant species to browsing by wallabies in a forest heavily infested with the invasive species, bitou bush Chrysanthemoides monilifera. We recorded the abundance and size of a range of plant species in 18 unfenced (browsed) and 16 fenced (unbrowsed) plots. We found the abundance and size of bitou bush was suppressed in browsed plots compared to unbrowsed plots. Regenerating seedlings of the canopy or middle storey tree species Eucalyptus pilularis, Acacia implexa, Allocasuarina littoralis, Breynia oblongifolia and Banksia integrifolia were either smaller or fewer in number in grazed plots than treatment plots as were the vines Kennedia rubicunda, Glycine tabacina and Glycine clandestina. In contrast, the understorey fern, Pteridium esculentum increased in abundance in the browsed plots relative to unbrowsed plots probably because of reduced competition with more palatable angiosperms. Twelve months after plots were installed the community structure of the browsed and unbrowsed plots was significantly different (P = 0.023, Global R = 0.091). The relative abundance of C. monilifera and P. esculentum contributed most to the differences. We discuss the possible development of a low diversity bracken fern parkland in Booderee National Park through a trophic cascade, similar to that caused by overabundant deer in the northern hemisphere. We also discuss its implications for broad scale fox control in southern Australian forests.

Molecular evolution of a novel marsupial S100 protein (S100A19) which is expressed at specific stages of mammary gland and gut development.

S100 proteins are calcium-binding proteins involved in controlling diverse intracellular and extracellular processes such as cell growth, differentiation, and antimicrobial function. We recently identified a S100-like cDNA from the tammar wallaby (Macropus eugenii) stomach. Phylogentic analysis shows wallaby S100A19 forms a new clade with other marsupial and monotreme S100A19, while this group shows similarity to eutherian S100A7 and S100A15 genes. This is also supported by amino acid and domain comparisons. We show S100A19 is developmentally-regulated in the tammar wallaby gut by demonstrating the gene is expressed in the forestomach of young animals at a time when the diet consists of only milk, but is absent in older animals when the diet is supplemented with herbage. During this transition the forestomach phenotype changes from a gastric stomach into a fermentation sac and intestinal flora changes with diet. We also show that S100A19 is expressed in the mammary gland of the tammar wallaby only during specific stages of lactation; the gene is up-regulated during pregnancy and involution and not expressed during the milk production phase of lactation. Comparison of the tammar wallaby S100A19 protein sequence with S100 protein sequences from eutherian, monotreme and other marsupial species suggest the marsupial S100A19 has two functional EF hand domains, and an extended His tail. An evolutionary analysis of S100 family proteins was carried out to gain a better understanding of the relationship between the S100 family member functions. We propose that S100A19 gene/protein is the ancestor of the eutherian S100A7 gene/protein, which has subsequently modified its original function in eutherians. This modified function may have arisen due to differentiation of evolutionary pressures placed on gut and mammary gland developmental during mammal evolution. The highly regulated differential expression patterns of S100A19 in the tammar wallaby suggests that S100A19 may play a role in gut development, which differs between metatherians and eutherians, and/or include a potential antibacterial role in order to establish the correct flora and protect against spiral bacteria in the immature forestomach. In the mammary gland it may protect the tissue from infection at times of vulnerability during the lactation cycle.

Kangaroo tooth enamel oxygen and carbon isotope variation on a latitudinal transect in southern Australia: implications for palaeoenvironmental reconstruction.

Tooth enamel apatite carbonate carbon and oxygen isotope ratios of modern kangaroos (Macropus spp.) collected on a 900-km latitudinal transect spanning a C(3)-C(4) transition zone were analysed to create a reference set for palaeoenvironmental reconstruction in southern Australia. The carbon isotope composition of enamel carbonate reflects the proportional intake of C(3) and C(4) vegetation, and its oxygen isotope composition reflects that of ingested water. Tooth enamel forms incrementally, recording dietary and environmental changes during mineralisation. Analyses show only weak correlations between climate records and latitudinal changes in δ(13)C and δ(18)O. No species achieved the δ(13)C values (~-1.0 ‰) expected for 100 % C(4) grazing diets; kangaroos at low latitudes that are classified as feeding primarily on C(4) grasses (grazers) have δ(13)C of up to -3.5 ‰. In these areas, δ(13)C below -12 ‰ suggests a 100 % C(3) grass and/or leafy plant (browse) diet while animals from higher latitude have lower δ(13)C. Animals from semi-arid areas have δ(18)O of 34-40 ‰, while grazers from temperate areas have lower values (~28-30 ‰). Three patterns with implications for palaeoenvironmental reconstruction emerge: (1) all species in semi-arid areas regularly browse to supplement limited grass resources; (2) all species within an environmental zone have similar carbon and oxygen isotope compositions, meaning data from different kangaroo species can be pooled for palaeoenvironmental investigations; (3) relatively small regional environmental differences can be distinguished when δ(13)C and δ(18)O data are used together. These data demonstrate that diet-isotope and climate-isotope relationships should be evaluated in modern ecosystems before application to the regional fossil record.

Haematology and biochemistry of warru (Petrogale lateralis MacDonnell Ranges race) in captivity and the wild.

OBJECTIVE: Use haematology, biochemistry and protein electrophoresis analyses to establish reference values for, and describe the health status of, wild and captive colonies of critically endangered warru (black-footed rock-wallaby: Petrogale lateralis MacDonnell Ranges race). METHODS: Blood samples were taken from warru in three wild colonies (Alalka, Kalka, New Well) in the A nangu Pitjantjatjara Yankunytjatjara Lands in north-west South Australia (SA) and from captive animals at Monarto Zoo, SA. General haematology, serum biochemistry and protein electrophoresis analyses were conducted and results used to establish reference ranges. For the parameters that are indicative of a population's health, comparisons among the study sites were completed using analysis of variance. RESULTS: General haematology results suggested that warru were not experiencing chronic anaemia and the protein electrophoresis values indicated that colonies were not suffering from population-wide disease. However, the lower superoxide dismutase, retinol, total carotenoids and ascorbic acid values for New Well warru suggested those animals had a lower plane of nutrition than those at Kalka and Alalka. Higher urea concentrations in New Well and Alalka warru could be a reflection of the absence of reliable free water at these sites. CONCLUSION: The results have implications for the management of in situ colonies, including potentially using supplementary feeding to improve nutrition, and suggested that these animals were not suffering from disease. The study presents the first blood reference values for P. lateralis and, potentially, a methodology for other threatened species recovery programs to follow to establish the health of their populations.

Extinction implications of a chenopod browse diet for a giant Pleistocene kangaroo.

Kangaroos are the world's most diverse group of herbivorous marsupials. Following late-Miocene intensification of aridity and seasonality, they radiated across Australia, becoming the continent's ecological equivalents of the artiodactyl ungulates elsewhere. Their diversity peaked during the Pleistocene, but by approximately 45,000 years ago, 90% of larger kangaroos were extinct, along with a range of other giant species. Resolving whether climate change or human arrival was the principal extinction cause remains highly contentious. Here we combine craniodental morphology, stable-isotopic, and dental microwear data to reveal that the largest-ever kangaroo, Procoptodon goliah, was a chenopod browse specialist, which may have had a preference for Atriplex (saltbushes), one of a few dicots using the C(4) photosynthetic pathway. Furthermore, oxygen isotope signatures of P. goliah tooth enamel show that it drank more in low-rainfall areas than its grazing contemporaries, similar to modern saltbush feeders. Saltbushes and chenopod shrublands in general are poorly flammable, so landscape burning by humans is unlikely to have caused a reduction in fodder driving the species to extinction. Aridity is discounted as a primary cause because P. goliah evolved in response to increased aridity and disappeared during an interval wetter than many it survived earlier. Hunting by humans, who were also bound to water, may have been a more decisive factor in the extinction of this giant marsupial.

Development of structural and functional connectivity in the thalamocortical somatosensory pathway in the wallaby.

Neuronal activity is implicated as a driving force in the development of sensory systems. In order for it to play a developmental role, however, the pathways involved must be capable of transmitting this activity. The relationship between afferent arrival, synapse formation and the onset of chemical neurotransmission has been examined using the advantageous model of a marsupial mammal, the wallaby (Macropus eugenii), to determine at what stage activity has the capacity to influence cortical development. It is known that thalamocortical afferents arrive in the somatosensory cortex on postnatal day (P)15 and that their growth cones reach to the base of the compact cell zone of the cortical plate. However, electronmicroscopy showed that thalamocortical synapses were absent at this stage. Glutamatergic responses were recorded in the cortex following stimulation of the thalamus in slices at this time but only in magnesium-free conditions. The responses were mediated entirely by N-methyl-d-aspartate (NMDA) receptors. From P28, responses could be recorded in normal magnesium and comprised a dominant NMDA-mediated component and a non-NMDA mediated component. At this time thalamocortical synapses were first identified and they were in the cortical plate. By P63 the non-NMDA-mediated component had increased relative to the NMDA-mediated component, and by P70 layer IV began to emerge and contained thalamocortical synapses. By P76 a fast non-NMDA-mediated peak dominated the response. This coincides with the appearance of cortical whisker-related patches and the onset in vivo of responses to peripheral stimulation of the whiskers.

An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia.

How well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene. Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare. Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction.

How do soil nutrients affect within-plant patterns of herbivory in seedlings of Eucalyptus nitens?

This study assessed how the palatability of leaves of different age classes (young, intermediate and older) of Eucalyptus nitens seedlings varied with plant nutrient status, based on captive feeding trials with two mammalian herbivores, red-bellied pademelons (Thylogale billardierii), and common brushtail possums (Trichosurus vulpecula). Seedlings were grown under three nutrient treatments (low, medium and high), and we determined how palatability was related to chemical and physical characteristics of the leaves. Pademelons ate more older leaves than young and intermediate leaves for all treatments. This pattern was best explained by sideroxylonals (formylated phloroglucinol compounds known to deter herbivory by other marsupials), and/or essential oil compounds that were present in lower concentrations in older leaves. In the low-nutrient treatment, possums also ate more of the older leaves. However, in the medium- and high-nutrient treatments, possums ate more intermediate leaves than older leaves and showed a behavioural preference for young leaves (consuming younger leaves first) over intermediate and older leaves, in spite of high levels of sideroxylonals and essential oils. The young leaves did, however, have the highest nitrogen concentration of all the leaf age classes. Thus, either sideroxylonals and essential oils provided little or no deterrent to possums, or the deterrent was outweighed by other factors such as high nitrogen. This study indicates that mammalian herbivores show different levels of relative use and damage to leaf age classes at varying levels of plant nutrient status and, therefore, their impact on plant fitness may vary with environment.

Whisker maps in marsupials: nerve lesions and critical periods.

In the wallaby, whisker-related patterns develop over a protracted period of postnatal maturation in the pouch. Afferents arrive simultaneously in the thalamus and cortex from postnatal day (P) 15. Whisker-related patterns are first seen in the thalamus at P50 and are well formed by P73, before cortical patterns first appear (P75) or are well developed (P85). This study used the slow developmental sequence and accessibility of the pouch young to investigate the effect of nerve lesions before afferent arrival, or at times when thalamic patterns are obvious but cortical patterns not yet formed. The left infraorbital nerve supplying the whiskers was cut at P0-93 and animals were perfused at P112-123. Sections through the thalamus (horizontal plane) and cortex (tangential) were reacted for cytochrome oxidase to visualize whisker-related patterns. Lesions of the nerve at P2-5, before innervation of the thalamus or cortex, resulted in an absence of patterns at both levels. Lesions from P66-77 also disrupted thalamic and cortical patterns, despite the fact that thalamic patterns are normally well established by P73. Lesions from P82-93 resulted in normal thalamic and cortical patterns. Thus, despite the wallaby having clearly separated times for the development of patterns at different levels of the pathway, these results suggest a single critical period for the thalamus and cortex, coincident with the maturation of the cortical pattern. Possible mechanisms underpinning this critical period could include dependence of the thalamic pattern on corticothalamic activity or peripheral signals to allow consolidation of thalamic barreloids.

Postnatal development of orexin-A and orexin-B like immunoreactivities in the Eastern grey kangaroo (Macropus giganteus) hypothalamus.

The Eastern grey kangaroo (Macropus giganteus) is a marsupial, which is born in an extremely undeveloped state and has a long suckling period in the mother's pouch. In the present study, we examined the immunoreactivities of orexin-A (OXA) and orexin-B (OXB) in the hypothalamus of the Eastern grey kangaroo during the preweaning period, postweaning period and adulthood. In the preweaning period, only a few OXA- and OXB-like immunoreactive (LI) neurons and fibers were present and the intensity of staining was very weak. In the postweaning period, there was a pronounced increase in the numbers of OXA- and OXB-LI neurons and fibers and the intensity of the immunoreactivity was considerably stronger in comparison to the preweaning period. In the adult, the numbers of OXA- and OXB-LI neurons and fibers appeared to be slightly increased and the intensity was slightly stronger in comparison to the postweaning period. At all time periods, the distributions of OXA- and OXB-LI neurons was similar. The postnatal development of hypothalamic orexin neurons may be associated with developmental changes, including feeding behavior.

Sexual differentiation in three unconventional mammals: spotted hyenas, elephants and tammar wallabies.

The present review explores sexual differentiation in three non-conventional species: the spotted hyena, the elephant and the tammar wallaby, selected because of the natural challenges they present for contemporary understanding of sexual differentiation. According to the prevailing view of mammalian sexual differentiation, originally proposed by Alfred Jost, secretion of androgen and anti-Mullerian hormone (AMH) by the fetal testes during critical stages of development accounts for the full range of sexually dimorphic urogenital traits observed at birth. Jost's concept was subsequently expanded to encompass sexual differentiation of the brain and behavior. Although the central focus of this review involves urogenital development, we assume that the novel mechanisms described in this article have potentially significant implications for sexual differentiation of brain and behavior, a transposition with precedent in the history of this field. Contrary to the "specific" requirements of Jost's formulation, female spotted hyenas and elephants initially develop male-type external genitalia prior to gonadal differentiation. In addition, the administration of anti-androgens to pregnant female spotted hyenas does not prevent the formation of a scrotum, pseudoscrotum, penis or penile clitoris in the offspring of treated females, although it is not yet clear whether the creation of masculine genitalia involves other steroids or whether there is a genetic mechanism bypassing a hormonal mediator. Wallabies, where sexual differentiation occurs in the pouch after birth, provide the most conclusive evidence for direct genetic control of sexual dimorphism, with the scrotum developing only in males and the pouch and mammary glands only in females, before differentiation of the gonads. The development of the pouch and mammary gland in females and the scrotum in males is controlled by genes on the X chromosome. In keeping with the "expanded" version of Jost's formulation, secretion of androgens by the fetal testes provides the best current account of a broad array of sex differences in reproductive morphology and endocrinology of the spotted hyena, and androgens are essential for development of the prostate and penis of the wallaby. But the essential circulating androgen in the male wallaby is 5alpha androstanediol, locally converted in target tissues to DHT, while in the pregnant female hyena, androstenedione, secreted by the maternal ovary, is converted by the placenta to testosterone (and estradiol) and transferred to the developing fetus. Testicular testosterone certainly seems to be responsible for the behavioral phenomenon of musth in male elephants. Both spotted hyenas and elephants display matrilineal social organization, and, in both species, female genital morphology requires feminine cooperation for successful copulation. We conclude that not all aspects of sexual differentiation have been delegated to testicular hormones in these mammals. In addition, we suggest that research on urogenital development in these non-traditional species directs attention to processes that may well be operating during the sexual differentiation of morphology and behavior in more common laboratory mammals, albeit in less dramatic fashion.

Comparative analysis of ATRX, a chromatin remodeling protein.

The ATRX protein, associated with X-linked alpha-thalassaemia, mental retardation and developmental abnormalities including genital dysgenesis, has been proposed to function as a global transcriptional regulator within a multi-protein complex. However, an understanding of the composition and mechanics of this machinery has remained elusive. We applied inter-specific comparative analysis to identify conserved elements which may be involved in regulating the conformation of chromatin. As part of this study, we cloned and sequenced the entire translatable coding region (7.4 kb) of the ATRX gene from a model marsupial (tammar wallaby, Macropus eugenii). We identify an ATRX ancestral core, conserved between plants, fish and mammals, comprising the cysteine-rich and SWI2/SNF2 helicase-like regions and protein interaction domains. Our data are consistent with the model of the cysteine-rich region as a DNA-binding zinc finger adjacent to a protein-binding (plant homeodomain-like) domain. Alignment of vertebrate ATRX sequences highlights other conserved elements, including a negatively charged mammalian sequence which we propose to be involved in binding of positively charged histone tails.