Digestive performance and selective digesta retention in the long-nosed bandicoot,Perameles nasuta,a small omnivorous marsupial

Bandicoots are opportunistic omnivores that feed on invertebrates, fungi and both epigeal and hypogeal plant parts. We examined the performance of the digestive tract of the long-nosed bandicoot (Perameles nasuta) in terms of intake and total digestibility, patterns of excretion of inert digesta markers, and likely sites of digesta retention, on two diets designed to mimic part of their natural plant and insect diets. On the insect diet (mealworm larvae), bandicoots virtually maintained body mass at a digestible energy intake of 511 kJ · kg^-0.75 · day^-1 and were in strongly positive nitrogen balance. In contrast, on the plant diet (shredded sweet potato), bandicoots ate only one-third as much digestible energy, lost 7% body mass, and were in negative nitrogen balance. Mean retention times of two particle markers on the plant diet (27.5 and 27.0 h) were more than double those on the insect diet (12.4 and 11.2 h), and on both diets the mean retention time of the fluid digesta marker was greater than those of the particle markers, indicating consistent selective retention of fluid digesta in the gut. It was seen radiographically than in mealwormfed bandicoots major sites of digesta retention were the distal colon and rectum, whereas in the sweet potato-fed animals the caecum and proximal colon were principal sites. It was concluded that retention of plant material in the caecum and proximal colon (the main sites of microbial digestion) and the preferential retention of fluid digesta (together with bacteria and small feed particles) in the caecum were important factors in the ability of bandicoots to switch between insect and plant foods, depending on relative availabilities, and thus to exploit nutritionally unpredictable environments.Abbreviations ADF acid-detergent fibre - bm body mass - Co-ED-TA cobalt-ethylenediaminetetra-acetic acid - CWC cell wall constituents - DE digestable energy - dm dry matter - EUN endogenous urinary nitrogen - ICP inductively-coupled plasma atomic emission spectroscopy - MFN metabolic faecal nitrogen - MRT mean retention time - NDF neutral-detergent fibre - ww wet weight     

Habitat selection of the long‐nosed bandicoot,Perameles nasuta (Mammalia,Peramelidae), in a patchy urban environment

Habitat selection in an omnivorous marsupial, the long‐nosed bandicoot, Perameles nasuta Geoffroy, was investigated in an urban environment with both natural and highly modified habitats at North Head, New South Wales, Australia. Habitat use at both macro‐ and microhabitat scales was determined using live‐trapping, and P. nasuta was shown to be a habitat specialist at this site. At night, animals used open grass macrohabitats disproportionately more for foraging than other macrohabitats. Trap‐revealed macrohabitat use was supported by radiotracking three males. Lack of understorey and absence of leaf litter were the major microhabitat features affecting habitat choice, although soil type probably also had some effect. Open areas may provide a more abundant and/or accessible food supply for P. nasuta, although better manoeuvrability or increased visibility to detect predators may also be important. Diurnal nest sites, located using radiotracking, were primarily in dense scrub vegetation, often comprising introduced species of plants. The dependence of P. nasuta on: (i) dense undergrowth for diurnal nesting and temporary nocturnal sheltering; and (ii) open areas for foraging indicates the importance of conserving a mosaic of open and dense vegetation to ensure the continued persistence of this endangered population at North Head.     

VNTR loci reveal differentiation between and structure within populations of the eastern barred bandicoot Perameles gunnii

The Eastern Barred Bandicoot Perameles gunnii has declined in abundance within mainland south-eastern Australia, to a relict wild population of less than 100 individuals in Hamilton, Victoria. It is more common, but is also declining in Tasmania. Genomic DN A variability was compared within and between surviving populations of P. gunnii using variable number of tandem repeat (VNTR) markers in one of two ways. First, average percentage differences (APDs) were determined between profiles for two VNTR probe—endonuclease combinations. Secondly, because one of these combinations revealed two multiallelic VNTR loci, genotypes were assigned and analysed for homogeneity of allele frequencies among subpopulations, for deviation of heterozygosity from Hardy-Weinberg equilibrium within populations and for genetic structuring among individuals from different subpopulations. The results of both the APD and defined locus approaches showed consistent trends within and between populations. Genetic variability was higher among mainland P. gunnii than in Tasmanian populations (higher APDs, number of alleles, and heterozygosity at one locus), despite the known decline and subdivision of the Hamilton population. Eleven per cent of the variability detected in Hamilton was attributed to genetic differentiation between east and west subdivisions of the population. Departure from random mating indicating local inbreeding within collecting localities was evident for one locus in both north and south Tasmania, particularly at one locality. AH alleles at both loci were unique to either Hamilton or Tasmanian P. gunnii. The initial captive colony contains high heterozygosity for these loci. It is concluded that VNTR markers can be of benefit for use in studies of population differentiation and for conservation management.     

Shivering and non-shivering thermogenesis in a marsupial,the eastern barred bandicoot (Perameles gunnii)

We investigated the metabolic rate of the Tasmanian marsupial, the eastern barred bandicoot, Perameles gunnii, before and after acclimation to cold temperature (5 °C) for a 2-week period. Although body temperature did not change significantly, we observed a significant increase in the metabolic rate (MR) when measured at 5 °C before and after cold acclimation. Nor-epinephrine had a significant effect on the metabolic rate when measured in the thermoneutral zone and when measured at 5 °C after cold acclimation; however, there was no significant increase when measured at 5 °C before cold acclimation. Nor-epinephrine also resulted in a small but significant decrease in body temperature. Electromyography (EMG) measurements were obtained before and after cold acclimation during shivering. Shivering decreased after two weeks of cold exposure indicating that the bandicoot had acclimated to that temperature. Nor-epinephrine (NE) significantly reduced shivering before but not after cold acclimation. The metabolic rate and shivering decreased in the adult eastern barred bandicoot after acclimation at 5 °C and nor-epinephrine had similar effects to cold acclimation. Our findings of minor changes in thermal conductance suggest that insulation differences were unlikely explanations for our results. These experiments indicate that this marsupial is able to increase its heat production by non-shivering thermogenesis.     

The development of endothermy during pouch life in the eastern barred bandicoot (Perameles gunnii), a marsupial

Marsupials are born ectothermic and gradually become endothermic during pouch occupancy. In order to study the timing of this transition, we measured the metabolic rates of eight pouch-young eastern barred bandicoots (Perameles gunnii) at 25 degrees C (the thermoneutral zone of adults), at 35 degrees C (pouch temperature), and after injection with norepinephrine. From 5 to 7 wk of age, oxygen consumption (VO(2)) was higher at 35 degrees C than at 25 degrees C. At 8 wk, VO(2) was significantly higher at 25 degrees C than at 35 degrees C. Norepinephrine administration at 5 and 6 wk had no effect on metabolic rate, but at 8 wk, near pouch vacation, it resulted in a significant increase in metabolic rate. Our results indicate that signs of thermoregulation for P. gunnii begin at 7 wk, and at 8 wk the species is endothermic, that is, able to increase heat production in response to both cold and norepinephrine. The appearance of fur, first seen at the age of 6 wk and fully developed at 8 wk, coincides with the onset of endothermy.     

A species in decline: genetic diversity and conservation of the Victorian eastern barred bandicoot, Perameles gunnii

The eastern barred bandicoot, Perameles gunnii, has undergone a dramatic decline in distribution and abundance on the mainland of Australia during the twentieth century. In 1988 a captive breeding program was initiated to reduce the chance of extinction. With the extinction of the last wild mainland population in the early 1990s, reintroductions from captive-bred P. gunnii have met limited success, and currently only two extant populations persist in predator proof enclosures in the State of Victoria. With ~20 years of breeding, there are concerns that the genetic diversity within the breeding program has declined and may inhibit current and future success of the program. We have used ten nuclear microsatellite loci and sequencing of two partial mitochondrial genes (cytochrome oxidase I and ATPase 6) to determine genetic diversity within current Victorian P. gunnii. These diversity estimates are compared with historic samples from the captive breeding program dating back to 1995, historic samples from the last wild mainland population found at Hamilton in 1992 and contemporary Tasmanian wild populations. Results indicate that the captive P. gunnii population in the State of Victoria has lost significant genetic diversity through time. Genetic diversity is also reduced in populations at Hamilton Community Parklands and Mount Rothwell. Samples from the last wild population at Hamilton collected in 1992, along with samples from Tasmanian P. gunnii, had significantly greater genetic diversity than contemporary mainland populations. The results are discussed with reference to management options for maintaining genetic diversity within Victorian P. gunnii, including crossing Victorian and Tasmanian P. gunnii to increase genetic diversity, adaptability and evolutionary potential.     

Wnt control of stem cells and differentiation in the intestinal epithelium

The intestinal epithelium represents a very attractive experimental model for the study of integrated key cellular processes such as proliferation and differentiation. The tissue is subjected to a rapid and perpetual self-renewal along the crypt-villus axis. Renewal requires division of multipotent stem cells, still to be morphologically identified and isolated, followed by transit amplification, and differentiation of daughter cells into specialized absorptive and secretory cells. Our understanding of the crucial role played by the Wnt/beta-catenin signaling pathway in controlling the fine balance between cell proliferation and differentiation in the gut has been significantly enhanced in recent years. Mutations in some of its components irreversibly lead to carcinogenesis in humans and in mice. Here, we discuss recent advances related to the Wnt/beta-catenin signaling pathway in regulating intestinal stem cells, homeostasis, and cancer. We emphasize how Wnt signaling is able to maintain a stem cell/progenitor phenotype in normal intestinal crypts, and to impose a very similar phenotype onto colorectal adenomas.     

Observations on the laternal vaginae and birth canals in the marsupials Isoodon macrourus and Perameles nasuta (Mammalia)

The laternal vaginae in the bandicoots Isoodon macrourus and Perameles nasuta wer long, straight and tabular, and consisted of a mascular sheath, an intermediate connective tissue layer and a luminal epithelium. The muscle layer had an inwardly projecting longitudinal ridge in I. macrourus but not in P. nasuta . In both species, a glassy layer was present immediately below the epithelium which was usually stratified columnar in type, although a non-keratinzing squamous type occured in small regions in some P. nasuta during pregnancy. The distance between the lateral vaginae in the birth canal region increased during pregnancy and reached a maximum at birth. The birth canal lacked an epithelial lining and was patent in some animals for more than half the lactation period. The allantoic stalks were often retained within the birth canal region throughout the lactation period and in some animals during the next pregnancy and even during the early part of the subsequent lactation     

Ultrastructural differentiation of the epithelium and mucous glands of the esophagus in the chick embryo

Esophagi of White Leghron chick embryos, six days to hatching, were fixed in 5% glutaraldehyde in a cacodylate-sucrose buffer, postfixed in 1% OsO₄, dehydrated and embedded in Araldite. Tissues were sectioned with glass knives and viewed with a Philips EM 100C. The epithelium in early stages of development is characterized by small intercellular spaces, few cell processes and few desmosomes. In contrast the differentiated epithelium contains numerous cell processes, large intercellular spaces and numerous desmosomes. Mucin appeared in the mucous glands at 17 days.     

Ultrastructural differentiation and enzymatic localization of phosphatases in the developing duodenal epithelium of the mouse

Summary The localization of acid and alkaline phosphatase activities during the morphogenesis of the duodenum has been studied at the ultrastructural level in BALB/c mice. The present work deals with the foetal development from the 14th day till birth. It appears that acid phosphatase activity at the 14th day of foetal life, was situated in dense bodies at the base of the intestinal cells. At that moment, the flat apical membrane of the cells lining the intestinal lumen presented a faint alkaline phosphatase activity. With the maturation of the villus cells, the dense bodies migrated to a supra-nuclear zone, and on the 20th day, differentiated into a complex network of dense bodies and dense tubules showing the activity of the two phosphatases. On the other hand, the microvilli were developing from the 16th day, and active pinocytosis appeared on the 18th day. Alkaline phosphatase activity increased rapidly during this differentiation.This study was supported by a research grant no. N.D.G./27 from the Medical Research Council of Canada.The authors are indebted to Mr. Michel Couture for his assistance with the photographs.     

Ultrastructural observations on the cell surface of the intestinal epithelium of the nematode,Ascaris suum

Summary The intestinal epithelium of Ascaris suum consists of a single layer of tall columnar epithelial cells that rest on a thick basal membrane in contact with the pseudocoelomic cavity. Experiments were conducted on glutaraldehyde-fixed tissue to ascertain the nature of the electronegative charges associated with both the apical microvillar surface and basal membrane.A strong electronegative charge was demonstrated on the microvillar surface and basal membrane with ruthenium red and cationic ferritin staining. The ionic nature of ferritin binding was demonstrated with poly-L-lysine, a polycation that interacts with anionic groups on the membrane and thus blocks the subsequent binding of ferritin. Tissue thus treated was devoid of reaction product. Methylation with diazomethane completely abolished staining. Since the stronger acidic groups of sulfates or phosphates would not be protonated under the conditions employed in this study, and therefore susceptible to methylation, staining by ferritin is thought to be due to its interaction with carboxyl groups. Prior enzymatic treatment of tissue with neuraminidase or phospholipase C had no effect on subsequent ferritin binding. Tissue exposed to colloidal iron at various pH values showed maximal reactivity at a pH of 2.5 or above. Above pH 2.5, the dissociation of protons from free carboxyl groups of protein-bound amino-acid residues with pK's of 3.8 and 4.2 would be maximal, and the ionized carboxyl groups are then available to interact with iron micelles. These results suggest the presence of weaker acidic groups, such as the carboxyl groups of acidic amino acids or uronic acid residues. The stronger acidic groups of sialic acid and the esterified sulfate groups, if present, contribute only minimally to overall staining. These results demonstrate that a high electronegative charge density exists, despite the apparent lack of sialic acid. Staining is believed to be due to carboxyl groups of acidic amino acids and/or carboxyl groups or uronic acid residues.Part of this work was conducted at the Department of Zoology, Louisiana State University, Baton Rouge, Louisiana     

Ultrastructural specialization of intestinal epithelium over Peyer's patches in the bonnet monkey, Macaca radiata.

The follicle associated epithelium (FAE) which separates the lymphoid follicle of Peyer's patch from the gut lumen is known to have specialized cells called M cells or "microfold" cells in man and certain animals. These cells are considered to be involved in antigen uptake and transport. Our light microscopic study of the small intestine of bonnet monkeys suggested the presence of such specialised cells in FAE. We have confirmed the presence of M cells in bonnet monkey FAE having ultrastructural features very similar to those of human M cells.     

Habitat‐dependent population regulation in an irrupting population of long‐nosed bandicoots (Perameles nasuta)

We used isodars to analyse habitat‐dependent population regulation by long‐nosed bandicoots Perameles nasuta during an irruption and subsequent population crash in three habitats (heath, woodland and forest) at Booderee National Park, south‐eastern Australia. Specifically, we aimed to see whether patterns of habitat‐dependent population regulation matched a priori estimates of quantitative and qualitative differences between habitats. We also tested if habitat preference changed between the increasing and decreasing phase of the irruption as predicted by the reciprocating dispersal theory. Quantitative differences in habitat quality were indexed by the relative abundance of the main food of long‐nosed bandicoots (terrestrial invertebrates), while qualitative differences were indexed by the availability of refuge from predation (vegetation understorey density). One index of fitness, body weight, was highest in forest, and lowest in heath, suggesting an ideal despotic model of habitat selection. Over the entire course of the irruption, there was density‐dependent habitat selection with forest and woodland both quantitatively superior to heath. This reflected the overall abundance of invertebrates with highest abundance in woodland and forest and less in heath. Isodar analysis also revealed that although forest was quantitatively better than heath and equivalent to woodland it was qualitatively poorer than either habitat. Heath had a higher density of understorey than woodland and woodland having a higher density of understorey than forest giving crossover population regulation. When the increasing and declining phase of the irruption were analysed separately, no habitat was quantitatively superior to any other during either phase. The lack of switching in preference between habitats from the increasing to the declining phase of the irruption and the virtual absence of any dispersal by adults, does not support the reciprocating dispersal hypothesis.     

Carbohydrate differentiation antigens of murine T cells: expression on intestinal lymphocytes and intestinal epithelium

Carbohydrate differentiation antigens (CT antigens) which previously had been shown to be associated with cytotoxic T cells were found at high levels on intestinal intraepithelial lymphocytes (IEL) and on the intestinal epithelium. Histological examination of intestinal sections demonstrated that the CT1 MAb defined epitopes on IEL and on epithelial cells located in the base of the villi crypts. The CT2 MAb reacted with IEL but also bound to the majority of cells in the intestinal epithelium. When isolated intestinal cell populations were analyzed by flow cytometry, two major size classes of cells were evident. The smaller cells, corresponding to lymphocytes, were primarily Lyt-2+, with a high proportion expressing CT antigens. Another differentiation antigen defined by the MAb J11d was absent from IEL, indicating that those IEL of T cell origin are likely to be mature because thymocytes, but not peripheral T cells, express the J11d antigen. Two-color fluorescence analysis indicated that the CT determinants were present on the Thy-1+, Lyt-2+, and the Thy-1-, Lyt-2+ subsets of IEL. However, the small percentage of L3T4+ IEL were CT-, further supporting our previous demonstration of a correlation between CT expression and Lyt-2 expression. Interesting phenotypic characteristics of IEL other than CT antigen expression were also detected. IEL did not express the MEL-14 lymphocyte homing receptor, and the cell surface level of LFA-1 was significantly lower than that of other peripheral lymphocytes. It was also shown that a small percentage of IEL express a T cell receptor allotypic marker, indicating that at least some of the cells are mature in terms of T cell receptor gene rearrangements. The large intestinal cells, although CT+, were not hematopoietic in origin because they were T200- and were shown by using chimeric mice not to be bone marrow-derived. In contrast to previously reported results, the cytotoxic activity of IEL was negligible with detectable lysis against NK-sensitive cells and other tumor cells, being observed in only one of seven experiments. Thus, the expression of the CT determinants was not indicative of cytotoxic ability, as previously suggested. The presence of specific carbohydrate residues on the cell surface of a subset of lymphocytes in an anatomically distinct immune compartment suggests that a unique differentiation pathway is followed by these cells.     

Factors influencing the occurrence of the Southern Long‐nosed Bandicoot (Perameles nasuta Geoffroy) during a population irruption and decline

Modelling the occupancy of species is a key part of the discipline of ecology, with particular efforts often focused on identifying which environmental, vegetation and other factors influence why a given species occurs where it does. Here, based on data gathered between 2003 and 2016, we developed models of the environmental, terrain and vegetation factors associated with site occupancy of the Southern Long‐nosed Bandicoot (Perameles nasuta Geoffroy) at Booderee National Park in the Jervis Bay Territory, south‐eastern Australia. The Long‐nosed Bandicoot is a nocturnal omnivorous marsupial which feeds primarily on subterranean invertebrates and fungi. The species has undergone a major reduction in abundance and site occupancy following a peak irruption in 2006 with the percentage of the sites at which the species was present declining from 74.3% of sites trapped in 2006 to 10.5% of sites trapped in 2016. We found the Long‐nosed Bandicoot was distributed widely across Booderee National Park and occurred in all six broad vegetation types in the reserve (forest, heathland, woodland, shrubland, sedgeland and rainforest). Detection‐occupancy modelling revealed that the persistence and colonisation of sites by the species were negatively associated with the per cent cover of leaf litter, irrespective of broad vegetation type. Occupancy models are an important tool in identifying parts of landscapes most likely to support populations of particular species, such as the Long‐nosed Bandicoot over time, and they may assist management of protected areas to prioritise resources to manage the habitat of those areas.     

A novel virus detected in papillomas and carcinomas of the endangered western barred bandicoot (Perameles bougainville) exhibits genomic features of both the Papillomaviridae and Polyomaviridae

Conservation efforts to prevent the extinction of the endangered western barred bandicoot (Perameles bougainville) are currently hindered by a progressively debilitating cutaneous and mucocutaneous papillomatosis and carcinomatosis syndrome observed in captive and wild populations. In this study, we detected a novel virus, designated the bandicoot papillomatosis carcinomatosis virus type 1 (BPCV1), in lesional tissue from affected western barred bandicoots using multiply primed rolling-circle amplification and PCR with the cutaneotropic papillomavirus primer pairs FAP59/FAP64 and AR-L1F8/AR-L1R9. Sequencing of the BPCV1 genome revealed a novel prototype virus exhibiting genomic properties of both the Papillomaviridae and the Polyomaviridae. Papillomaviral properties included a large genome size ( approximately 7.3 kb) and the presence of open reading frames (ORFs) encoding canonical L1 and L2 structural proteins. The genomic organization in which structural and nonstructural proteins were encoded on different strands of the double-stranded genome and the presence of ORFs encoding the nonstructural proteins large T and small t antigens were, on the other hand, typical polyomaviral features. BPCV1 may represent the first member of a novel virus family, descended from a common ancestor of the papillomaviruses and polyomaviruses recognized today. Alternatively, it may represent the product of ancient recombination between members of these two virus families. The discovery of this virus could have implications for the current taxonomic classification of Papillomaviridae and Polyomaviridae and can provide further insight into the evolution of these ancient virus families.