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Category: Digestion, nutrition & metabolism

A survey of pesticide accumulation in a specialist feeder, the koala (Phascolarctos cinereus)

Marschner, C, Higgins, DP & Krockenberger, MB 2017, Bulletin of Environmental Contamination and Toxicology, vol. 99, no. 1, p. 303-307.

This study is the first to examine exposure to and effects of pesticides in koalas. In all tissue samples from koalas that inhabited areas impacted by horticultural, agricultural or urban development, pesticide levels were consistently below the limit of detection. This finding suggests that, for these koalas, chronic ongoing or acute exposure to pesticides was unlikely.

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Category: Digestion, nutrition & metabolism

Administration of a 5HT3 receptor antagonist increases the intake of diets containing Eucalyptus secondary metabolites by marsupials

Lawler, IR, Foley, WJ, Pass, GJ & Eschler, BM 1998, Journal of Comparative Physiology B, vol. 168, no. 1, pp. 611-618.

Jensenone, an acylphloroglucinol derivative that is a secondary metabolite in Eucalyptus, was found to cause common ringtail and brushtail possums to regulate their food intake to consume only a defined maximum amount. Injecting jensenone into possums’ stomachs reduced their food consumption so as not to exceed a maximum dosage, although individuals responded variably. After injecting ondansetron, an antagonist of serotonin 5HT3 receptors, the maximum amount of food able to be consumed increased significantly, suggesting that jensenone’s negative effects occur by acting on 5HT3 serotonin receptors, thereby causing ‘nausea’ and food aversion.

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Category: Anatomy & physiology

Age-dependent changes in gross and histological morphology of the thyroid gland in South Australian koalas (Phascolarctos cinereus)

Graham, C, Woolford, L, Johnson, L & Speight, KN 2014, Australian Journal of Zoology, vol. 62, pp. 360-365.

This study investigated the morphological changes of the koala thyroid gland, which were determined to be linked to the age of the koala, rather than health status or sex. Juvenile koalas were mostly observed to exhibit typical thyroid gland morphology, while most adult koalas presented with colloidal goitre. The authors suggest an association of the findings with the low metabolism of koalas or dietary goitrogen exposure.

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Category: Digestion, nutrition & metabolism

An investigation of streptococcal flora in faeces of koalas

Osawa, RO 1991, Journal of Wildlife Management, vol. 55, no. 4, pp. 623-627.

The occurrence, counts and biochemical characteristics of streptococcal flora in koala faeces differ according to sex and living environment. Female koalas have approximately ten times more of the tannin-protein complex degrading (T-PCD) Streptococcus bovis bacterium in their faeces than males. Strains of T-PCD S. bovis were not only more dominant among the faecal streptococcal of free-ranging koalas than of captive koalas but were also biochemically unique between each group. The enterococci S. faecalis and S. faecium were found only in the faeces of captive koalas, indicating that the bacteria were spread from humans or other animals.

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Category: Anatomy & physiology

Assessment of the hemorheological profile of koala and echidna

Baskurt, OK, Marshall-Gradisnik, S, Pyne, M, Simmonds, M, Brenu, E, Christy, R & Meiselman, J 2010, Zoology, vol. 113, no. 2, pp. 110-117.

Blood samples from six echidnas and six koalas were analysed and compared to human blood for the following parameters: red blood cell (RBC) deformability, RBC aggregation, surface charge and aggregability, blood viscosity (62.5-1250 s -1) and hematological characteristics. The koalas had the highest average RBC volume (107.7 ± 2.6 fl) out of humans (88.4 ± 1.2 fl) and echidnas (81.3 ± 2.6 fl). RBC deformability of the koala was significantly greater than that of both human and echidna. RBCs of the echidna had less aggregability than human or koala RBCs, whilst aggregation was comparable for all three species in autologous plasma. RBC surface charge was similar between echidnas and humans, but 40% less in koalas by comparison.

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Category: Infection & disease

Atypical presentation of Cryptococcus neoformans in a koala (Phascolarctos cinereus): a magnetic resonance imaging and computed tomography study

Martínez-Nevado, E, Alonso-Alegre, EG, Martínez, MÁ, Rodríguez-Álvaro, A, de Merlo, EM, García, JG & Real, IG 2017, Journal of Zoo and Wildlife Medicine, vol. 48, no. 1, pp. 250-254.

Magnetic resonance imaging (MRI) and computed tomography (CT) are valuable tools for diagnosing cryptococcosis in koalas as the techniques, used together, can assist in identifying the precise location and extent of a granuloma.

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Category: Digestion, nutrition & metabolism

Bark chewing reveals a nutrient limitation of leaves for a specialist folivore

Au, J, Youngentob, KN, Clark, RH, Phillips, R & Foley, WJ 2017, Journal of Mammalogy, vol. 98, no. 4, pp. 1185-1192.

Koalas of the subalpine Monaro region in New South Wales appear to have developed the unusual adaptation of chewing the sodium-rich bark of Eucalyptus mannifera to meet their nutritional requirements within a landscape that is otherwise lacking in the mineral micronutrient.

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Category: Evolution

Bearing up well? Understanding the past, present and future of Australia's koalas

Black, KH, Price, GJ, Archer, M & Hand, SJ 2014, Gondwana Research, vol. 25, pp. 1186-1201.

Evidence from fossil records of the family Phascolarctidae indicates that these specialist folivores, of which the modern koala Phascolarctos cinereus is the last surviving member, are particularly sensitive to climate change. Knowledge about the nature and rate of change in previous palaeocommunities of phascolarctids together with data relating to the responses of modern koala populations to historic climatic extremes indicate that the future survival of the species is under threat.

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Category: Anatomy & physiology

Bony Orbital Anatomy of the Koala (Phascolarctos cinereus)

Kempster, RC & Hirst, LW 2002, The Anatomical Record, vol. 267, pp. 288-291.

This study was the first to document anatomical details of the normal koala orbit, which showed consistencies in the overall orbital structure compared with other marsupials. This information can be used to improve understandings of the koala’s anatomy and aid research efforts to find treatments for ocular disease in the koala.

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Category: Infection & disease

Case study: Iatrogenic diabetes mellitus in a koala (Phascolarctos cinereus) receiving treatment with prednisolone

Lathe, SE 2016, Journal of Wildlife Rehabilitation, vol. 36, no. 2, pp. 7-10.

A female koala that was brought into a wildlife hospital developed diabetes mellitus during treatment with prednisolone. After cessation of prednisolone treatment, blood glucose levels in the koala decreased to below the nominal reference range.

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Category: Infection & disease

Characterisation of CD4 T cells in healthy and diseased koalas (Phascolarctos cinereus) using cell-type-specific monoclonal antibodies

Manger, C, Armitage, CW, Timms, P, Corcoran, LM & Beagley, KW 2016, Developmental and Comparative Immunology, vol. 60, no. 1, pp. 80-90.

An initial cell-type-specific monoclonal antibody (mAb) for koalas has been developed. The anti-CD4 mAb is able to detect CD4+ T lymphocytes at various bodily sites using a range of analytical techniques. The mAb can also be used to detect vaccine-induced Chlamydia-specific CD4+ T cells in the peripheral blood mononuclear fragments of immunised koalas.

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Category: Digestion, nutrition & metabolism

Characterisation of gram-negative anaerobic strains, isolated from koala faeces, which exhibit satellite growth and pleomorphism

Osawa, RO, Fujusawa, T & Mitsuoka, T 1992, Systematic and Applied Microbiology, vol. 15, no. 1, pp. 628-635.

As part of a series of studies investigating the characteristics of koala faecal microflora, three strains of anaerobic gram-negative bacteria which demonstrated satellitism around colonies of Escherichia coli are described here.

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Category: Infection & disease

Characterisation of the koala biovar of Chlamydia pneumoniae of four gene loci – ompAVD4, ompB, 16S rRNA, groESL spacer region

Wardrop, S, Fowler, A, O’Callaghan, P, Giffard, P & Timms, P 1999, Systematic and Applied Microbiology, vol. 22, pp. 22-27. 

While there is significant genetic diversity in Chlamydia pecorum strains that infect koalas, little is known about genetic diversity of C. pneumoniae. DNA sequences of four gene fragments were found to be different between koala, human and horse C. pneumoniae biovars. Two gene loci, ompAVD4 and ompB, were identical among all isolates from koalas. This study, for the first time, reports on a respiratory infection associated with C. pneumoniae in a captive koala population.

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Category: Anatomy & physiology

Characteristics of koala (Phascolarctos cinereus adustus) semen collected by artificial vagina

Johnston, SD, O’Callaghan, P, McGowan, MR & Phillips, NJ 1997, Journal of Reproduction and Fertility, vol. 109, no. 1, pp. 319-323.

An artificial vagina is recommended as a simple, reliable and non-invasive method of semen collection from koalas in captivity. Out of 90 attempts, 40% resulted in collection of a complete ejaculate comprising a rubbery copulatory plug fraction and a sperm fraction with high motile spermatozoa content. No semen was collected in 38% of trials, while only partial ejaculates were collected in 14.5% of trials. Urine was detected in 4.5% of samples, and 3% of semen samples were collected after the koala’s ejaculation behaviour had ended.

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Category: Digestion, nutrition & metabolism

Cloning and expression of koala (Phascolarctos cinereus) liver cytochrome P450 CYP4A15

Ngo, SNT, McKinnon, RA & Stupans, I 2006, Gene, vol. 376, p. 123-132.

Digestion of eucalyptus oil compounds, or monoterpenes, is thought to be done by liver enzymes called cytochromes P450 (CYP). In the past it has been reported that koala liver has increased hydroxylation of lauric acid, a fatty acid, which is indicative of CYP4A enzyme activity. The molecular and enzymatic characteristics of CYP4A in koala liver are reported in this study.

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Category: Digestion, nutrition & metabolism

Complete genome sequence of the Streptococcus gallolyticus subsp. gallolyticus Strain DSM 16831

Grimm, I, Dumke, J, Vollmer, T, Hinse, D, Rückert, C, Kalinowski, J, Knabbe, C & Dreier, J 2017, Genome Announcements, vol. 5, no. 16,  e00108-17.

The complete genome sequence of Streptococcus gallolyticus subsp. gallolyticus strain DSM 16831, found in koala faeces and noted for its low virulence compared to other isolates, has been determined and reported here.

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Category: Digestion, nutrition & metabolism

Composition of preferred and rejected Eucalyptus browse offered to captive koalas, Phascolarctos cinereus (Marsupialia)

Ullrey, DE, Robinson, PT & Whetter, PA 1981, Australian Journal of Zoology, vol. 29, pp. 839-846.

Browse from eleven species of Eucalyptus tree shoots or mature limbs were offered to captive koalas at the San Diego Zoo, California and subsequently sorted into ‘preferred’ or ‘rejected’ species. Analyses revealed that, compared to rejected browse, preferred browse contained significantly higher crude protein, remaining proximate fraction, potassium and phosphorus concentrations and significantly lower neutral detergent fibre, acid detergent fibre, ether extract, calcium, iron, selenium, permanganate lignin, and gross energy concentrations.

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Category: Digestion, nutrition & metabolism

Cytochrome P450 4A, peroxisomal enzymes and nicotinamide cofactors in koala liver

Ngo, S, Kong, S, Kirlich, A, McKinnon, RA & Stupans, I 2000, Comparative Biochemistry and Physiology Part C, vol. 127, no. 1, pp. 327-334.

Microsomal lauric acid hydroxylase activity and cyanide-insensitive palmitoyl coenzyme A oxidative (CIPCO) activity were examined in koala, tammar wallaby and rat liver. The microsomal lauric acid hydroxylation was higher in the koala than either the wallaby or rat, whereas CIPCO activity was completely absent in the koala. Hepatic nicotinamide cofactors were observed for all three species, with nicotinamide-adenine dinucleotide (NAD) levels and the ratio of NAD to NAD phosphate (NADP) higher in koalas than either of the other species. A cloned cDNA for CYP4A from the koala was found to be ~70% similar to human CYP4A11, prompting its naming as CYP4A15.

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Category: Digestion, nutrition & metabolism

Dental microwear texture analysis of extant koalas: clarifying causal agents of microwear

Hedberg, C & DeSantis, LRG 2016, Journal of Zoology, vol. 301, no. 1, pp. 206-214.

The dental microwear of the koala is consistent with that of other tough object feeders and reflects its dietary composition and behaviours. The most likely factors influencing microwear patterns in the koala are the properties of food consumed, abrasion during mastication and the ingestion of grit.

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Category: Digestion, nutrition & metabolism

Detection of Helicobacter species in the gastrointestinal tract of ringtail possum and koala: Possible influence of diet, on the gut microbiota

Coldham, T, Rose, K, O’Rourke, J, Neilan, BA, Dalton, H, Lee, A & Mitchell, H 2013, Veterinary Microbiology, vol. 166, pp. 429-437.

Cultures from the liver and distinct regions of the gastrointestinal tract (GIT) revealed no Helicobacter species to be present in studied koalas. Deoxyribonucleic acid (DNA) extraction from stomach mucus scrapings and homogenised livers enabled gene sequencing of the 16S rRNA gene which was later identified to be of Helicobacter species. Examination of liver and intestine sections using histopathological methods further showed that the presence of Helicobacter was not related to infection.

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Category: Infection & disease

Detection of koala retrovirus subgroup B (KoRV-B) in animals housed at European zoos

Fiebig, U, Keller, M & Denner, J 2016, Archives of Virology, vol. 161, pp. 3549-3553.

In addition to the common endogenous koala retrovirus KoRV-A, a second type of non-endogenous retrovirus, KoRV-B, was recently detected in animals in zoos in Japan and the United States. This study describes a different type of KoRV-B detected in koalas from zoos in Germany and Belgium.

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Category: Digestion, nutrition & metabolism

Dietary specialisation and Eucalyptus species preferences in Queensland koalas (Phascolarctos cinereus)

Higgins, AL, Bercovitch, FB, Tobey, JR & Hamlin Andrus, C 2011, Zoo Biology, vol. 30, no. 1, pp. 52-58.

Koalas appear to demonstrate individual dietary preferences for different species of Eucalyptus and an overall preference for particular species; however, the factors driving these preferences are not yet understood.

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Category: Digestion, nutrition & metabolism

Digestion and nitrogen metabolism in the koala, Phascolarctos cinereus

Harrop, CJF & Degabriele, R 1976, Australian Journal of Zoology, vol. 24, no. 1, pp. 201-215.

The koala’s digestive tract is shown here to be well-suited to the consumption of fibrous Eucalyptus leaves. The caecum, the sac at the beginning of the large intestine that stores food in herbivores and allows bacteria to break down cellulose, was large, as would be expected for a specialised mammalian herbivore. Koalas maintained a positive but low nitrogen level over the experimental period, with digestibility of nitrogen lower in winter, requiring more nitrogen to be consumed. This was demonstrated by mean nitrogen balances and apparent digestible nitrogen intakes not being significantly different between summer and winter, and the daily dietary nitrogen intakes differing significantly between seasons (0.426 g/kg W0.75 in summer and 0.493 g/kg W0.75 in winter).

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Category: Genetics

DNA fingerprint analysis of a free-range koala population

Timms, P, Kato, J, Maugeri, M & White, N 1993, Biochemical Genetics, vol. 31, no. 9/10, pp. 363-374.

This paper presents the first detailed genetic study of a large group of wild koalas in Queensland using the DNA fingerprinting technique.

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Category: Genetics

DNA profiling of Queensland koalas reveals sufficient variability for individual identification and parentage determination

Cocciolone, RA & Timms, P 1992, Wildlife Research, vol. 19, pp. 279-287.

DNA profiling of captive and free-range groups of koalas in Queensland detected genetic variation and differentiated between individuals using restriction enzymes (Msp I and Bam HI) and M13 probe.  Specific DNA profiles were produced to identify individuals with an average genetic variation of 17%.  These DNA profiles can be used for exploring genetic relatedness and social structure in both captive and wild populations of koalas.

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Category: Digestion, nutrition & metabolism

Effects of acidic and alkaline treatments on tannic acid and its binding property to protein

Osawa, R & Walsh, TP 1993, Journal of Agricultural and Food Chemistry, vol. 41, no. 1, pp. 704-707.

Tannin-protein complexes that must be broken down in the gut of the koala dissociated under highly acidic and highly alkaline conditions in vitro in an environment designed to simulate the marsupial’s stomach.

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Category: Infection & disease

Epidemiology of chlamydial infection and disease in a free-ranging koala (Phascolarctos cinereus) population

Nyari, S, Waugh, CA, Dong, J, Quigley, BL, Hanger, J, Loader, J, Polkinghorne, A & Timms, P, 2017, PloS One, vol. 12, no. 12, e0190114.

The aim of this study was to analyse the epidemiology of infection and disease caused by Chlamydia in a koala population from Queensland. It was found that, out of 160 koalas tested, 31% were positive for Chlamydia and 28% exhibited clinical signs of chlamydial disease, with most infections observed at the urogenital and ocular sites.

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Category: Infection & disease

Epizootiology of Chlamydia infections in two free-range koala populations

Jackson, M, White, N, Giffard, P & Timms, P 1999, Veterinary Microbiology, vol. 65, no. 1, pp. 255-264.

This study is the first to use DNA-based assay techniques to compare the prevalence and epizootiology of the chlamydial species infecting koalas in two free-ranging koala populations in Queensland.

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Category: Infection & disease

Expression and in vitro upregulation of MHCII in koala lymphocytes

Lau, Q, Canfield, PJ & Higgins, DP 2012, Veterinary Immunology and Immunopathology, vol. 147, pp. 35-43.

The purpose of this study was to characterise class II major histocompatibility complex (MHCII) in koalas in terms of abundance and distribution between sexes and seasons, and further to evaluate MHCII as a marker of lymphocyte activation during in vitro studies. Flow cytometry found that the expression of MHCII was upregulated within activated B lymphocytes in cell culture, but not koalas with active inflammation. Furthermore, MHCII was found to be expressed predominantly on circulating B lymphocytes rather than on T lymphocytes.

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Category: Evolution

Family-level relationships among the Australasian marsupial ‘‘herbivores’’ (Diprotodontia: Koala, wombats, kangaroos and possums)

Phillips, MJ & Pratt, RC 2008, Molecular Phylogenetics and Evolution, vol. 46, pp. 594-605.

This study attempts to determine the phylogenetic relationships between families in Diprotodontia, a diverse order of marsupials occupying a range of niches across Australasia, including koalas, wombats, kangaroos and possums.  Using mitochondrial and nuclear sequences, phylogenetic analysis serves to resolve relationships that were previously inconclusive, specifically between Vombatiformes and Phalangerida groupings.

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Category: Digestion, nutrition & metabolism

Foliage of Eucalyptus punctata and the maintenance nitrogen requirements of koalas, Phascolarctos cinereus

Cork, SJ 1986, Australian Journal of Zoology, vol. 34, pp. 17-23.

In an analysis of foliage fed to captive koalas, winter foliage was found to have a lower nitrogen content than summer foliage; however, this was compensated for by the koalas eating more during winter. Nitrogen balance in the koalas was, therefore, not significantly different between the seasons. Similarly, the excretion of nitrogen did not change seasonally but the non-dietary losses of nitrogen in the faeces were higher in the winter compared to summer.

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Category: Digestion, nutrition & metabolism

Formation of a clear zone on tannin-treated brain heart infusion agar by a Streptococcus sp. isolated from faeces of koalas

Osawa, RO 1990, Applied and Environmental Microbiology, vol. 56, no. 3, pp. 829-831.

A strain of tannin-protein complex degrading bacterium was identified in the faeces of koalas. Colonies of the isolate formed a clear zone on a tannin-treated brain heart infusion agar and were characterised as Streptococcus bovis biotype I.

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Category: Genetics

Genetic diversity and gene flow among southeastern Queensland koalas (Phascolarctos cinereus)

Fowler, EV, Houlden, BA, Hoeben, P & Timms, P 2000, Molecular Ecology, vol. 9, pp. 155-164.

The extraction of DNA among southeastern Queensland koalas showed significant genetic diversity between most populations indicating that these populations are most likely structured along matrilines, in which individuals are considered to belong to the same descent group as their mother. 

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Category: Infection & disease

Genetic diversity of Chlamydia pecorum strains in wild koala locations across Australia and the implications for a recombinant C. pecorum major outer membrane protein based vaccine

Kollipara, A, Polkinghorne, A, Wan, C, Kanyoka, P, Hanger, J, Loader, J, Callaghan, J, Bell, A, Ellis, W, Fitzgibbon, S, Melzer, A, Beagley, K & Timms, P 2013, Veterinary Microbiology, vol. 167, pp. 513-522.

The genetic diversity of Chlamydia pecorum strains in koalas has limited the production of an effective cross-strain vaccine. By examining C. pecorum isolates from koalas across their range, the most common major outer membrane protein (MOMP) amino type F was suggested to be a prime candidate for recombinant C. pecorum vaccine development.

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Category: Genetics

Genetic diversity of Chlamydia pecorum strains in wild koala locations across Australia and the implications for a recombinant C. pecorum major outer membrane protein based vaccine

Kollipara, A, Polkinghorne, A, Wan, C, Kanyoka, P, Hanger, J, Loader, J, Callaghan, J, Bell, A, Ellis, W, Fitzgibbon, S, Melzer, A, Beagley, K & Timms, P 2013, Veterinary Microbiology, vol. 167, pp. 513-522.

The genetic diversity of Chlamydia pecorum strains in koalas has limited the production of an effective cross-strain vaccine. By examining C. pecorum isolates from koalas across their range, the most common major outer membrane protein (MOMP) amino type F was suggested to be a prime candidate for recombinant C. pecorum vaccine development.

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Category: Life history

Gestational length in the koala, Phascolarctos cinereus

Gifford, A, Fry, G, Houlden, BA, Fletcher, TP & Deane, EM 2002, Animal Reproduction Science, vol. 70, no. 1, pp. 261-266.

A koala born at Taronga Zoo was found to have a gestational period of at least 50 and up to 77 days, considerably longer than the typical gestational length of 30-35 days.

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Category: Life history

Growth and development of the koala from birth to weaning

Blanshard, WH 1991, in Lee, AK, Handasyde, KA & Sanson, GD (ed.), Biology of the Koala, Surrey Beatty and Sons, Chipping Bay, pp. 193-202.

Several observations of the developmental changes in the physical appearance, dentition and behaviour of koalas during the 12-month period from birth to weaning have been compiled and documented.

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Category: Life history

Growth and mortality of koala pouch and back young

O’Callaghan, P 1996, Proceedings from the Conference on the Status of the Koala in 1996, Brisbane, Australian Koala Foundation, pp. 101-109.

The systematic management and monitoring of captive koala populations presents a unique opportunity for learning about the growth and mortality of koala pouch and back young. In this report, a number of learnings about the factors affecting the development of juvenile koalas from the Lone Pine Koala Sanctuary koala population are documented.

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Category: Digestion, nutrition & metabolism

Hepatic nuclear receptor PPARα in the koala (Phascolarctos cinereus): Cloning and molecular characterisation

Ngo, SNT, McKinnon, RA & Stupans, I 2007, Comparative Biochemistry and Physiology, part C, vol. 146, pp. 375-382.

Peroxisome proliferator-activated receptor α, or PPARα, is a protein that is involved in lipid homeostasis. It controls gene expression of certain enzymes, such as CYP4As, which play a role in digesting eucalyptus leaves. The molecular characteristics of PPARα in koala liver are reported in this study.

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Category: Infection & disease

Heterogeneity of koala retrovirus isolates

Shimode, S, Nakagawa, S, Yoshikawa, R, Shojima, T & Miyazawa, T 2013, FEBS Letters, vol. 558, pp. 41-46.

Koala retrovirus (KoRV) is a gammaretrovirus implicated in immune suppression and leukemia, with three subgroups identified named A, B and J. Phylogenetic analysis demonstrated that KoRV-B and KoRV-J should be considered the same subgroup. A long terminal repeat (LTR) in KoRV-B had four 17 bp tandem repeats (‘DR-1’ for direct repeat 1) and in KoRV-J had three 37 bp tandem repeats (‘DR-2’). The promoter activity in the KoRV-J OJ-4 strain was stronger than in KoRV-A, suggesting more efficient replication.

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Category: Infection & disease

Histopathological and immunohistochemical investigation of naturally occurring chlamydial conjunctivitis and urogenital inflammation in koalas (Phascolarctos cinereus)

Hemsley, S & Canfield, PJ 1997, Journal of Comparative Pathology, vol. 116, no. 1, pp. 273-290.

This study reports the findings of a histopathological (changes in tissue as a result of disease) and immunohistochemical (using antibodies to test for antigens in tissue) examination of the conjunctiva and lower urogenital tract of koalas exhibiting symptoms of chlamydial disease. Antibodies were used to label T and B lymphocytes, plasma cells, major histocompatibility complex class II (MHC II)-positive cells and chlamydial antigen in order to improve our knowledge of the immune response and pathogenesis of chlamydiosis.

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Category: Infection & disease

Histopathological examination of the pancreas of the koala (Phascolarctos cinereus)

Higgins, DP & Canfield, PJ 2009, Journal of Comparative Pathology, vol. 140, no. 1, pp. 217-224.

Autolysis of pancreatic tissue from koalas was previously thought to make these samples unsuitable for histopathological examination; however, this study demonstrates that many abnormalities of the pancreas can be detected using established criteria for the stages of autolysis up to 72 hours post mortem.

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Category: Anatomy & physiology

Histopathological examination of the pancreas of the koala (Phascolarctos cinereus)

Higgins, DP & Canfield, PJ 2009, Journal of Comparative Pathology, vol. 140, no. 1, pp. 217-224.

Autolysis of pancreatic tissue from koalas was previously thought to make these samples unsuitable for histopathological examination; however, this study demonstrates that many abnormalities of the pancreas can be detected using established criteria for the stages of autolysis up to 72 hours post mortem.

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Category: Digestion, nutrition & metabolism

Identification and cloning of two forms of liver peroxisomal fatty Acyl CoA Oxidase from the koala (Phascolarctos cinereus)

Ngo, SNT, McKinnon, RA & Stupans, I 2003, Gene, vol. 309, no. 1, pp. 91-99.

Reverse transcription polymerase chain reaction was used to amplify two sections of koala liver acyl CoA oxidase (AOX) cDNA named AOX1 and AOX2. The two cDNAs were 2039 bp each, encoding for proteins of 662 amino acids in length. Transfection of these cDNAs into Cos-7 cells resulted in cells with palmitoyl-CoA oxidase activity. Apparent Km values (an inverse measure of affinity) were the same order of magnitude as rat and human AOX enzymes. Northern analysis found a more intense AOX mRNA band for koala liver than human and rat, and genomic DNA southern blot analysis found a single <14 kb AOX gene fragment in all three species. It is therefore likely that the lack of peroxisomal cyanide-insensitive palmitoyl-CoA oxidation activity in koala hepatic tissue is due to enzymes downstream of AOX or deficiencies in mitochondrial β-oxidation enzymes.

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Category: Infection & disease

Identification of koala T lymphocytes using an anti-human CD3 antibody

Wilkinson, R, Barton, M & Kotlarski, I 1995, Developmental and Comparative Immunology, vol. 19, no. 6, pp. 537-545.

Studying the immunobiology of koalas is important because koalas are prone to disease. Recently a new antibody, anti-CD3, has become available. To date koala T cells have not been identified using classic techniques. This study used anti-CD3 antibody to successfully bind T lymphocytes from koala’s peripheral blood. Anti-CD3 was found to bind a small polypeptide, likely similar to the original target – epsilon chain of the human CD3 complex.

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Category: Infection & disease

Identification, characterisation and expression analysis of natural killer receptor genes in Chlamydia pecorum infected koalas (Phascolarctos cinereus)

Morris, KM, Mathew, M, Waugh, C, Ujvari, B, Timms, P, Polkinghorne, A & Belov, K 2015, BMC Genomics, vol. 16, no 796.

The aim of this study was to characterise genes within the receptor clusters of natural killer (NK) cells of the koala. Analysis with quantitative polymerase chain reaction (qPCR) found that CLEC4E was upregulated in response to Chlamydia pecorum infection.

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Category: Infection & disease

Immuno-histochemical demonstration of the role of Chlamydiaceae in renal, uterine and salpingeal disease of the koala, and demonstration of Chlamydiaceae in novel sites

Higgins, DP, Hemsley, S & Canfield, PJ 2005, Journal of Comparative Pathology, vol. 133, no. 1, pp. 164-174.

The purpose of this study was to examine the distribution of chlamydial organisms in the kidneys and female upper reproductive tract of the koala and consequently characterise their role in disease. It was found that Chlamydiaceae contribute significantly to renal, uterine and salpingeal disease. Additionally, the report details a case study of a concurrent systemic infection with Chlamydiaceae and Gram-positive cocci.

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Category: Infection & disease

In vitro characterisation of koala Chlamydia pneumoniae: Morphology, inclusion development and doubling time

Mitchell, CM, Matthews, SA, Theodoropoulos, C & Timms, P 2009, Veterinary Microbiology, vol. 136, no. 1, pp. 91-99.

The Chlamydia pneumoniae koala nasal isolate termed LPCoLN was compared to the human isolate AR39 and differed significantly from the human isolate in terms of doubling time, size, and morphology.

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Category: Infection & disease

In vitro survival characteristics of koala Chlamydiae

Rush, CM & Timms, P 1996, Wildlife Research, vol. 23, no. 1, pp. 213-219.

Type I and II koala Chlamydia strains were compared to an avian C. psittaci strain. All three strains survived 4 hours of exposure to solutions ranging from pH 4 to 10, with Type I surviving best at pH 7.2-7.5 and Type II surviving optimally at pH 7.0-7.2. Type 1 elementary bodies remained viable for 28 days at temperatures of 18-23°C, but were inactivated within 5 minutes at 56°C. Avian chlamydiae survived 4-6 days after drying, whereas koala Type I only survived 2-4 days. Type I was also still infective after three days exposure on Eucalyptus tereticornis leaves. Overall, these results demonstrated that koala Type I Chlamydia is able to survive significant time periods under extreme conditions, meaning that non-sexual transmission is a possible transmission mechanism for the strain.

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Category: Infection & disease

Increased genetic diversity and prevalence of co-infection with Trypanosoma spp. in koalas (Phascolarctos cinereus) and their ticks identified using next-generation sequencing (NGS)

Barbosa, AD, Gofton, AW, Paparini, A, Codello, A, Greay, T, Gillett, A, Warren, K, Irwin, P & Ryan, U 2017, PLoS ONE, vol. 12, no. 7, e0181279.

Protozoan infections by Trypanosoma species can affect koala health. In this study koalas were found to harbor many different species of trypanosomes, and mixed infections by multiple species were more common than single infections. T. irwini was found to be the dominant species. Ticks collected from koalas may play a role in trypanosome transmission.

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Category: Digestion, nutrition & metabolism

Ingestion and excretion of Eucalyptus punctata D. C. and its essential oil by the koala, Phascolarctos cinereus (Goldfuss)

Eberhard, IH, McNamara, J, Pearse, RJ & Southwell, IA 1975, Australian Journal of Zoology, vol. 23, pp. 169-179.

This study describes a feeding trial during which ingestion and excretion by four captive koalas fed an exclusive diet of Eucalyptus punctata punctata was examined. Findings showed that 60% of leaf dry matter was digestible and of the volatile oil ingested, an insignificant proportion was excreted, with 7-30% passing through to the faeces and 1% in the urine.

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Category: Infection & disease

Interleukin 17A is an immune marker for chlamydial disease severity and pathogenesis in the koala (Phascolarctos cinereus)

Mathew, M, Waugh, C, Beagley, KW, Timms, P & Polkinghorne, A 2014, Development and Comparative Immunology, vol. 46, pp. 423-429.

Chlamydial disease is a significant threat to the survival of koala populations, with management and control of this pathogen restricted by a narrow insight into the koala’s immune response. To develop a greater understanding of koala immunology, this study outlined the cytokine responses of immune cells sampled from koalas possessing chlamydial disease with varying stages of severity. Four different cytokines were targeted for inspection. Findings revealed significantly higher gene expression of Interleukin (IL) 17A (Th17 cytokine) in those koalas currently affected by chlamydial disease than those unaffected.

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Category: Anatomy & physiology

Intraorbital anatomy of the koala (Phascolarctos cinereus)

Kempster, RC, Bancroft, BJ & Hirst, LW 2002, The Anatomical Record, vol. 267, pp. 277-287.

Detailed descriptions of the koala anatomy generate baseline information for understanding and treating diseases in the koala. This study provides baseline anatomical details of the normal koala orbit, excluding the bulbus oculi.

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Category: Digestion, nutrition & metabolism

Investigation of the koala (Phascolarctos cinereus) hindgut microbiome via 16S pyrosequencing

Barker, CJ, Gillet, A, Polkinghorne, A & Timms, P 2013, Veterinary Microbiology, vol. 167, pp. 554-564.

Little is known about the diversity and composition of microorganisms involved in the koala’s digestive process. Consequently, this study performed rRNA gene pyrosequencing of caecum, colon and faecal samples from two wild koalas. Findings reveal a diverse and highly complex ecosystem, with considerable variation of microorganisms at the genus level between individuals.

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Category: Evolution

Is the modern koala (Phascolarctos cinereus) a derived dwarf of a Pleistocene giant? Implications for testing megafauna extinction hypotheses

Price, GJ 2008, Quaternary Science Reviews, vol. 27, pp. 2516-2521. 

This study tested the hypothesis that the modern Australian koala (Phascolarctos cinereus) is a dwarf descendent of the extinct giant koala (Ph. stirtoni), which underwent body-size reduction during the Late Pleistocene-Holocene period. The implication of this hypothesis is that Ph. stirtoni survived the megafaunal extinction event of the Late Pleistocene, with Ph. cinereus being the evolutionary ‘end-point’. Findings suggest that the giant koala should be considered a species distinct from the modern koala.

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Category: Infection & disease

Keratitis in free-ranging koalas (Phascolarctos cinereus) on Magnetic Island, Townsville

Hirst, LW, Brown, AS, Kempster R, Hall, J & Woolcock, JB 1992, Journal of Wildlife Diseases, vol. 28, no. 3, pp. 424-427.

Investigation of 70 free-ranging koalas from Magnetic Island, Queensland revealed that unilateral keratitis was present in 12 koalas and bilateral keratitis in a further 10 koalas. No Chlamydia psittaci was detected in any of the animals and disregarding various other medical conditions such as nasal discharge, there appeared to be no indication of ocular chlamydial infection.

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Category: Infection & disease

Koala retrovirus genotyping analyses reveal a low prevalence of KoRV-A in Victorian koalas and an association with clinical disease

Legione, AR, Patterson, JLS, Whiteley, P, Firestone, SM, Curnick, M, Bodley, K, Lynch, M, Gilkerson, JR, Sansom, FM & Devlin, JM 2017, Journal of Medical Microbiology, vol. 66, pp. 236-244.

The endogenisation of koala retrovirus (KoRV) has resulted in 100% prevalence of KoRV in koalas from New South Wales and Queensland. In contrast, this study found that there was a 24.7% prevalence of KoRV in koalas from Victoria. Additionally, the KoRV provirus was twice as likely to be detected in koalas exhibiting clinical symptoms of KoRV, such as ‘wet bottom’, than in koalas without symptoms.

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Category: Infection & disease

Lack of antiviral antibody response in koalas infected with koala retroviruses (KoRV)

Fiebig, U, Keller, M, Moller, A, Timms, P & Denner, J 2015, Virus Research, vol. 198, pp. 30-34.

The purpose of this study was to screen koala sera for antibodies against endogenous koala retrovirus, KoRV-A. Polymerase chain reaction (PCR) identified endogenous KoRV-A from the sera of all 16 koalas tested, with two koalas positive for exogenous KoRV-B. Further protein analyses with Western blot failed to identify antibodies specific for KoRV-A, which could indicate a state of tolerance.

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Category: Digestion, nutrition & metabolism

Levels of trace elements in the liver and diet of free-living koalas, Phascolarctos cinereus (Goldfuss)

McOrist, S & Thomas, KW 1984, Journal of Wildlife Diseases, vol. 20, no. 3, pp. 220-225.

In free-living koalas in Victoria, reference values were determined for a number of different trace elements in the liver and blood plasma. The findings were comprehensive, ultimately revealing suboptimal copper levels in both the plasma and liver, especially in older koalas. No significant trends with age were identified for cobalt, zinc or manganese levels.

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Category: Digestion, nutrition & metabolism

Lonepinella koalarum gen. nov., sp. nov., a new tannin-protein complex degrading bacterium

Osawa, R, Rainey, F, Fujisawa, T, Lang, E, Busse, HJ, Walsh, TP & Stackebrandt, E 1995, Systematic and Applied Microbiology, vol. 18, no. 1, pp. 368-373.

Osawa and colleagues explored the phylogeny of tannin-protein complex (T-PC)-degrading bacteria within faecal samples from koalas, which led to the proposal of a new genus and species of a bacterium named Lonepinella koalarum after the place at which it was discovered, Lone Pine Koala Sanctuary.

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Category: Genetics

Low genetic diversity and inbreeding depression in Queensland koalas 

Worthington-Wilmer, JM, Melzer, A, Carrick, F, & Moritz, C, 1993, Wildlife Research, vol. 20, pp. 177-188.

  Analysis of mitochondrial DNA (mtDNA) of two Queensland koala populations reveals that genetic variation within and between these population is extremely low, though the variation appears to be structured geographically.  Furthermore, the analysis also shows inbreeding levels in a captive colony in one of these populations to be moderate and high, but koalas within this colony do not show strong evidence of inbreeding depression apart from the male-biased sex ratio.

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Category: Digestion, nutrition & metabolism

Metabolism of tannin-protein complex by facultatively anaerobic bacteria isolated from koala faeces

Osawa, R, Walsh, TP & Cork, SJ 1993, Biodegradation, vol. 4, no. 1, pp. 91-99.

Isolates of tannin-protein complex-degrading enterobacteria (T-PCDE) and Streptococcus bovis biotype I from koala faeces can degrade protein complexed with the hydrolysable tannin gallotannin, but cannot degrade protein complexed with the condensed tannin quebracho. These bacteria could also metabolise gallic acid to pyrogallol, as could the faecal isolates Klebsiella pneumoniae and K. oxytoca, although these strains could not degrade tannin-protein complexes (T-PCs). None of the strains examined were able to further degrade pyrogallol to phloroglucinol, although pyrogallol did not occur in fresh koala faecal samples.

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Category: Digestion, nutrition & metabolism

Metabolites of dietary 1,8-cineole in the male koala (Phascolarctos cinereus)

Boyle, R, McLean, S, Foley, W, Davies, NW, Peacock, EJ & Moore, B 2001, Comparative Biochemistry and Physiology Part C, vol. 129, pp. 385-396.

Koalas detoxify and eliminate 1,8-cineole, a Eucalyptus monoterpene, through oxidation into several metabolites. The average 1,8-cineole intake of six male koalas was 2.4 ± 1.1 mmol/kg, of which 1.3 ± 0.4 and 1.4 ± 0.4 was recovered free and total, respectively, in urine and faeces in various forms. The identities and amounts of seven metabolites were found: 9- and 7-hydroxycineole, 9- and 7-cineolic acid, 7-hydroxy-9-cineolic acid, 9-hydroxy-7-cineolic acid and 7,9-dicineolic acid. Hydroxy-cineolic acids comprised 85% of the metabolic profile, with 7-hydroxy-9-cineolic acid accounting for 77% by itself, followed by 10% 7,9-dicineolic acid.

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Category: Digestion, nutrition & metabolism

Microbial studies of the intestinal microflora of the koala, Phascolarctos cinereus. II. Pap, a special maternal faeces consumed by juvenile koalas

Osawa, R, Blanshard, WH & O’Callaghan, PG 1993, Australian Journal of Zoology, pp. 611-620.

The presence of tannin-protein-complex-degrading enterobacteria (T-PCDE) present in ‘pap’, a faecal substance ingested by juvenile koalas, was found to be a prerequisite to obtaining protein from tannin-rich eucalyptus leaves. Microflora present in the faeces of female koalas during the production of pap was found to have a higher water content and pH (81.8%, 7.0 respectively) than faeces produced prior to the beginning of the pap feeding process (54.6-56.4%, 5.5). Counts of viable T-PCDE were found to be higher in pap while normal faeces contained less, with some samples testing negative for T-PCDE altogether.

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Category: Digestion, nutrition & metabolism

Microbiological studies of the intestinal microflora of the koala, Phascolarctos cinereus. I. Colonisation of the caecal wall by tannin-protein-complex-degrading enterobacteria

Osawa, R, Bird, PS, Harbrow, DJ, Ogimoto, K & Seymour, GJ 1993, Australian Journal of Zoology, vol. 41, no. 1, pp. 599-609.

Tannin-protein-complex-degrading enterobacteria (T-PCDE) normally occur in the bacterial layer bound to the wall of the caecum in koalas but are dangerously susceptible to antibiotic treatment. T-PCDE are suggested to maintain a symbiotic relationship with the host whereby the bacteria generate health benefits for the koala in exchange for its extensive colonisation of the intricate caecal wall.

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Category: Infection & disease

Microbiota composition of the koala (Phascolarctos cinereus) ocular and urogenital sites, and their association with Chlamydia infection and disease

Vidgen, ME, Hanger, J & Timms P 2017, Scientific Reports, vol. 7, article 5239

This study explored the potential associations between microbiota profiles at penile/urogenital and ocular sites, chlamydial infection status, and demographic factors in free-ranging koalas. It was found that the presence or absence of particular microbiota in the female urogenital tract may contribute to the progression of Chlamydia pecorum infection to disease at the site. Penile and urogenital tract microbiota, but not ocular microbiota, were also found to differ between the sexes and life stages.

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Category: Anatomy & physiology

Microflora of the pouch of the koala (Phascolarctos cinereus)

Osawa, R, Blanshard, WH & O’Callaghan, P 1992, Journal of Wildlife Diseases, vol. 28, no. 2, pp. 276-280.

The pouches of female koalas are resistant to microbial colonisation, with a majority of pouch swabs revealing no microbial growth. Of 17 female koalas, only four (24%) were observed to have bacterial or yeast growths in the pouch.

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Category: Infection & disease

Molecular characterisation and expression analysis of Interferon gamma in response to natural Chlamydia infection in the koala, Phascolarctos cinereus

Mathew, M, Pavasovic, A, Prentis, PJ, Beagley, KW, Timms, P & Polkinghorne, A 2013, Gene, vol. 527, pp. 570-577.

Transcriptome analyses of koalas have identified the sequence of the genes encoding koala interferon gamma (IFNγ), a cytokine involved in antimicrobial responses. By comparing tissues from cohorts of koalas with and without active Chlamydia infections using quantitative real time PCR (qPCR), significantly different expression patterns of IFNγ between both groups were observed.

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Category: Infection & disease

Molecular evidence for novel chlamydial infections in the koala (Phascolarctos cinereus)

Devereux, LN, Polkinghorne, A, Meijer, A & Timms, P 2003, Systematic and Applied Microbiology, vol. 26, pp. 245-253.

Infection with Chlamydia is common in wild koalas. C. pecorum and C. pneumoniae largely infect the eye, the genitourinary tract and the respiratory system of the koala. In this study, a commonly used method of polymerase chain reaction (PCR) was used to detect nine novel Chlamydia-like strains infecting koalas. A new technique using fragments of ribosomal RNA (rRNA) gene was developed to further evaluate these additional strains.

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Category: Genetics

Molecular phylogenetics of the Diprotodontia (kangaroos, wombats, koala, possums, and allies)

Osborne, MJ, Christidis, L & Norman, JA 2002, Molecular Phylogenetics and Evolution, vol. 25, pp. 219-228.

The evolutionary relationships of diprotodontid order marsupials (kangaroos, wombats, koala, possums and others) were analysed using ND2 mitochondrial sequences. The findings were also compared with 12S ribosomal DNA (rDNA) sequences. Groupings of organisms descending from a common ancestor, or monophyly, were found for Burramyoidea, Phalangeroidea, Petauroidea, Tarsipedoidea, Macropodoidea and the Vombatiformes (wombats and koala) sub-orders and super-families. Discrepancies between genetic findings and current taxonomic ranks were found.

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Category: Evolution

Molecular phylogenetics of the Diprotodontia (kangaroos, wombats, koala, possums, and allies)

Osborne, MJ, Christidis, L & Norman, JA 2002, Molecular Phylogenetics and Evolution, vol. 25, pp. 219-228.

The evolutionary relationships of diprotodontid order marsupials (kangaroos, wombats, koala, possums and others) were analysed using ND2 mitochondrial sequences. The findings were also compared with 12S ribosomal DNA (rDNA) sequences. Groupings of organisms descending from a common ancestor, or monophyly, were found for Burramyoidea, Phalangeroidea, Petauroidea, Tarsipedoidea, Macropodoidea and the Vombatiformes (wombats and koala) sub-orders and super-families. Discrepancies between genetic findings and current taxonomic ranks were found.

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Category: Infection & disease

Morbidity and Mortality in the Koala (Phascolarctos cinereus)

Backhouse, TC & Bolliger, A 1961, Australian Journal of Zoology, vol. 9, no.1, pp. 24-37.

Of 28 koalas autopsied in 1960, pneumonia was the leading cause of death in this mortality study, which also presented as a comorbidity with trauma. Other significant causes of death were hepatitis, yeast infections of the species Cryptococcus neoformans, leukaemia and anaemia. Ovarian cysts were observed in a number of the koalas, but it was only the cause of death for koalas whose cysts had become infected. Finally, senility-associated diseases such as cardiac failure were seen at a low level.

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Category: Digestion, nutrition & metabolism

Multifarious activities of cellulose degrading bacteria from Koala (Phascolarctos cinereus) faeces 

Singh, S, Thavamani, P, Megharaj, M & Naidu, R 2015, Journal of Animal Science and Technology, vol. 57, no. 3, pp. 1-6. 

  The most common bacteria found in koala faeces are Bacillus sp. and Pseudomonas sp. after isolation using carboxymethylcellulose-Congo red agar and hydrolytic enzyme activity screening in vitro. There were high activity levels for several enzymes, including xylanase, lignin peroxidase and amylase, with lower concentrations of endoglucanase activity. The isolates were also able to grow in the presence of phenanthrene, suggesting possible applications in bioremediation.

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Category: Infection & disease

Multiple intra-abdominal serosal myxosarcomas in two koalas (Phascolarctos cinereus)

Gonzalez Astudillo, V, Schaffer-White, A, Allavena, R & Palmieri, C 2015, Journal of Comparative Pathology, vol. 152, pp. 183-286.

Post-mortem examinations performed on two koalas revealed a thick accumulation of fluid in the abdomens. Many hard lumps filled with fluid were also found spread across the abdominal cavities. When examined under the microscope the lumps were found to contain cancer cells.

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Category: Digestion, nutrition & metabolism

Nutrients, antinutrients and leaf selection by captive koalas (Phascolarctos cinereus)

Hume, ID, & Esson C 1993, Australian Journal of Zoology, vol. 41, pp. 379-92.

Eucalyptus foliage selection by captive koalas is driven by a suite of variables rather than a single factor.  The present study revealed that foliage most preferred by captive koalas had higher volatile monoterpenes, which are the most aromatic oil component, and lower sesquiterpenes in their essential oils.  Moreover, the most preferred foliage had higher nitrogen to fibre ratio, lower condensed tannin content and higher ratio of nitrogen to condensed tannin content than rejected foliage.

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Category: Digestion, nutrition & metabolism

Occurrence of tannin-protein complex degrading Streptococcus sp. in faeces of various animals

Osawa, R & Sly, LI 1992, Systematic and Applied Microbiology, vol. 15, no. 1, pp. 144-147.

Strains of the tannin-protein complex (T-PC) degrading Streptococcus bovis bacterium occur more commonly in browsing and omnivorous animals than in grazing and carnivorous animals. S. bovis bacteria dominates the streptococcal flora in the faeces of koalas (59.9% of streptococcal flora) and ringtail possums (59.1% of streptococcal flora), which are both animals with diets consisting primarily of tannin-rich eucalypt leaves.

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Category: Infection & disease

One hundred twenty years of koala retrovirus evolution determined from museum skins

Avila-Arcoa, MC, Ho, SYW, Ishida, Y, Nikolaidis, N, Tsangaras, K, Hönig, K, Medina, R, Rasmussen, M, Fordyce, SL, Calvignac-Spencer, S, Willerslev, E, Gilbert, MTP, Helgen, KM, Roca, AL & Greenwood, AD 2013, Molecular Biology and Evolution, vol. 30, no. 2, pp. 299-304.

Historical DNA samples from museum-held koala skins displayed comparable proviral koala retrovirus (KoRV) envelope sequences to extant samples, suggesting the spread and subsequent infection of KoRV occurred over a greater period of time than previously thought. Being the only known retrovirus to be currently infecting its host’s germ line, KoRV has remained an issue for koalas since the 19th century and may have actually increased the susceptibility of koalas to chlamydial infection as a result of its evolving and expeditious nature. 

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Category: Anatomy & physiology

 

Ophthalmologic examination of the normal eye of the koala  

Hirst, LW, Brown, AS, Kempster, R & Winney, N 1992, Journal of Wildlife Diseases, vol. 28, no. 3, pp. 419 -423.  

  Examination of the eyes of 28 koalas (Phascolarctos cinereus) was performed to document the typical in vivo formation. 22 of the 28 investigated koalas had eyes that were normal. Upon examination using slit-lamps, the cornea was found to have atypical lamellae with average keratometric measurements at 59.3 ±  3 diopters. The measurement of the endothelial cell area of the cornea was 381.4 ± m2  ± 46.8 ± m2. No identifiable features that would explain the ocular infection susceptibility of this species by Chlamydia psittaci infection were noted.  

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Category: Infection & disease

Outer membrane protein 2 gene sequences indicate that Chlamydia pecorum and Chlamydia pneumoniae cause infections in koalas

Glassick, T, Giffard, P & Timms, P 1996, Systematic and Applied Microbiology, vol. 19, no. 1, pp. 457-464.

Seven strains of Chlamydia present in koalas that were all previously described as types of Chlamydia psittaci have been reclassified as either C. pneumoniae or C. pecorum following genetic sequence and phylogenetic analyses.

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Category: Infection & disease

Outer membrane protein A gene sequencing demonstrates the polyphyletic nature of koala Chlamydia pecorum isolates

Jackson, M, Giffard, P & Timms, P 1997, Systematic and Applied Microbiology, vol. 20, no. 1, pp. 187-200.

When the phylogenetic relationships of sequences of a chlamydial major outer membrane protein gene from Chlamydia pecorum isolates of both koala and non-koala origin were examined, the genotypes sequenced were found to be genetically distinct. Rather than being represented as a single branch in the C. pecorum phylogenetic tree, the koala isolates separated into five unique genotypes. Of these five genotypes, two were specific to koalas, and three were shared with sheep, cattle or pigs.

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Category: Infection & disease

Papillomavirus in healthy skin of Australian animals

Antonsson, A & McMillan, NAJ 2006, Journal of General Virology, vol. 87, no. 1, pp. 3195-3200.

Papillomaviruses have been detected in one monotreme and two marsupial species in Australia, including the koala. From samples taken from several captive animal environments across Queensland including Lone Pine Koala Sanctuary, three putative and potential new papillomavirus types in koalas were identified. Of those koalas sampled, 14% tested positive for papillomavirus DNA attributable to one of these three papillomavirus types. The putative new koala papillomavirus type KoAA1 is genetically distinct from all previously described human and animal papillomaviruses.

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Category: Infection & disease

Parasitic pneumonia in a koala (Phascolarctos cinereus) from Victoria, Australia

McColl, KA & Spratt, DM 1982, Journal of Wildlife Diseases, vol. 18, no. 4, pp. 511-512.

A very sick, mature male koala was presented to the Veterinary Research Institute, Victoria where examination showed only arthritis in the stifle joint. Microscopic analysis of lung tissue revealed a mild parasitic interstitial pneumonia. In the koala, a range of disease syndromes have been described, yet until now none have resulted from infiltration by parasitic helminths.

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Category: Digestion, nutrition & metabolism

Phenotypic characterisation of CO2-requiring strains of Streptococcus bovis from koalas

Osawa, R & Sly, LI 1991, Applied and Environmental Microbiology, vol. 57, no. 10, pp. 3037-3039.

Of six strains of the bacterium Streptococcus bovis sampled from koala faeces, two strains that were previously reported as anaerobic were found to be able to grow in oxygen-reduced air that was supplemented with carbon dioxide. The unique characteristic in these aerobic strains was likely the presence of the enzyme β-N-acetylglucosaminidase.

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Category: Infection & disease

Phylogenetic diversity of koala retrovirus within a wild koala population

Chappell, KJ, Brearley, JC, Amarilla, AA, Watterson, D, Hulse, L, Palmieri, C, Johnston, SD, Holmes, EC, Meers, J & Young, PR 2017, Journal of Virology, vol. 91, no. 3, e01820-16.

Koala retrovirus (KoRV) is widespread throughout koala populations, both wild and captive, and yet only nine different KoRV envelope sequences have thus far been described. From 18 koalas sampled from free-ranging populations in south-east Queensland, 108 unique sequences and four potentially new KoRV subtypes have been described here for the first time.

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Category: Infection & disease

Pneumonia due to Chlamydia pecorum in a koala (Phascolarctos cinereus)

Mackie, JT, Gillett, AK, Palmieri, C, Feng, T & Higgins, DP 2016, Journal of Comparative Pathology, vol. 155, no. 1, pp. 356-360.

This report documents a case of Chlamydia pecorum infection of the bronchiolar epithelium of the koala, causing pneumonia in a juvenile male.

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Category: Anatomy & physiology

Post-coital LH surge in the koala (Phascolarctos cinereus)

Johnston, SD, O’Callaghan, P, Nilsson, K & Curlewis, JD 2001, Proceedings of the 32nd Annual Conference of the Society for Reproductive Biology, 9 - 12 September, Gold Coast, p. 59.

This study puts forward initial evidence of a surge of luteinising hormone (LH) in female koalas. Occurring 24 hours after mating, the observed LH surge is considered to be induced by the act of copulation, though this is yet to be confirmed.

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Category: Infection & disease

Prevalence and clinical significance of herpesvirus infection in populations of Australian marsupials

Stalder, K, Vaz, PK, Gilkerson, JR, Baker, R, Whiteley, P, Ficorilli, N, Tatarczuch, L, Portas, T, Skogvold, K, Anderson, GA & Devlin, JM 2015, PloS One, vol. 10, no. 7, p. e0133807.

To date, molecular classification of herpesviruses in marsupial species has been limited. In this study, the presence of herpesviruses in several Australian marsupial species, including koalas, was identified and assessed for risk factors seen during herpesvirus infection. It was found that the presence of Chlamydia pecorum DNA in koalas was highly associated with the presence of herpesvirus DNA, which could suggest a co-infection dynamic.

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Category: Infection & disease

Prevalence and pathologic features of Chlamydia pecorum infections in South Australian koalas (Phascolarctos cinereus)

Speight, KN, Polkinghorne, A, Penn, R, Boardman, W, Timms, P, Fraser, T, Johnson, K, Faull, R, Bate, S & Woolford, L 2016, Journal of Wildlife Diseases, vol. 52, no. 2, pp. 301-306.

Previously thought to be of low prevalence in South Australian populations, chlamydial infection has been detected in a significant proportion of a subset of koalas from the region. For these koalas, however, infection does not necessarily lead to clinical disease.

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Category: Genetics

Randomly amplified polymorphic DNA variation in populations of eastern Australian koalas, Phascolarctos cinereus

Fowler, EV, Hoeben, P & Timms, P 1998, Biochemical Genetics, vol. 36, nos. 11/12, pp. 381-393.

An analysis of molecular variation in eight eastern Australian koala populations showed greater genetic diversity in northern koala populations from New South Wales and Queensland than in southern populations from Victoria and South Australia.  Population differentiation was evident based on the presence of polymorphisms in fragments of DNA amplified using randomly amplified polymorphic DNA (RAPD) as molecular markers. The genetic variation between individuals was twice as variable for northern populations than southern populations.

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Category: Life history

Relationships between morphometric variables and age for captive individuals may not accurately estimate the age of free-ranging juvenile koalas (Phascolarctos cinereus)

Tucker, GM, Clifton, ID & McKillup, SC 2012, Australian Journal of Zoology, vol. 60, no. 1, pp. 173-179.

The development and application of a model for determining the ages of free-ranging juvenile Queensland koalas based on morphometric variables suggests that similar models based on data obtained from captive animals may not be suitable for estimations of age of wild koalas.

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Category: Infection & disease

Retrovirus mutation rates and their role in genetic variation

Mansky, LM 1998, Journal of General Virology, vol. 79, pp. 1337-1345.

This study reviews information regarding retrovirus variation and the impacts it may have on the diversity and evolution of viruses, virus severity, pathogenesis, and the development of antiviral drugs and vaccines. The information produced by this study can be applied to koalas to increase our understanding of koala retrovirus, or KoRV.

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Category: Genetics

Retrovirus mutation rates and their role in genetic variation

Mansky, LM 1998, Journal of General Virology, vol. 79, pp. 1337-1345.

This study reviews information regarding retrovirus variation and the impacts it may have on the diversity and evolution of viruses, virus severity, pathogenesis, and the development of antiviral drugs and vaccines. The information produced by this study can be applied to koalas to increase our understanding of koala retrovirus, or KoRV.

Details
Category: Anatomy & physiology

Seasonal changes in haematocrit in captive koalas (Phascolarctos cinereus)

Cleva, GM, Stone, GM & Dickens, RK 1994, Australian Journal of Zoology, vol. 42, no. 2, pp. 233-236.

Distinct changes in microhaematocrit (ratio of red blood cell volume to the total blood volume) with season were observed in captive koalas, with raised levels in the winter and reduced values during the summer. Additionally, microhaematocrit was negatively correlated with the lowest and highest temperatures in the day. No associations of the differences in haematocrit with variations in body weight, plasma osmolarity or the concentration of plasma protein were discovered.

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Category: Life history

Seasonal oestrous cycle activity of captive female koalas in south-east Queensland

Ballantyne, K, Lisle, A, Mucci, A, Johnston, SD 2015, Australian Mammalogy, vol. 37, pp. 245-252.

Over a four-year period, 33 mature, captive female koalas were investigated regarding the seasonality of their oestrous behaviour, with the potential impacts of rainfall, temperature and photoperiod explored specifically. Findings revealed noticeable seasonality in behavioural oestrus, as well as a significant correlation between oestrous cycle activity and both average monthly temperature and photoperiod.

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Category: Anatomy & physiology

Seasonal reproduction in wild and captive male koala (Phascolarctos cinereus) populations in south-east Queensland

Allen, CD, de Villiers, DL, Manning, BD, Dique, DS, Burridge, M, Chafer, ML, Nicolson, VN, Jago, SC, McKinnon, AJ, Booth, RJ, McKee, JJ, Pyne, MJ, Peng Zee, Y, Lundie-Jenkins, G, Theilemann, P, Wilson, RJ, Carrick, FN & Johnston, SD 2010, Reproduction, Fertility and Development, vol. 22, no. 1, pp. 695-709.

Male koalas exhibit seasonal changes in anatomical and physiological characteristics relating to fertility and reproduction. These seasonal variations have implications for artificial insemination (AI) programmes, as semen samples collected from wild koalas during winter appear to retain the highest quality after thawing from cryopreservation.

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Category: Digestion, nutrition & metabolism

Seasonal variation in water flux, field metabolic rate and food consumption of free-ranging koalas (Phascolarctos cinereus)

Ellis, WAH, Melzer, A, Green, B, Newgrain, K, Hindell, MA & Carrick, FN 1995, Australian Journal of Zoology, vol. 43, pp. 59-68.

Male free-ranging koalas in central Queensland, Australia were found to have field metabolic rates (corrected for mass) that exhibited a variation of 0.382 MJ kg0.75 per day in the winter and 0.329 MJ kg0.75 per day during the summer. Measurements of influx of water in the same koalas were 59.9 mL kg0.8 per day during the summer and 50.8 kg0.8 per day in the winter. This water influx had a positive correlation with the moisture values in the consumed food. Water influx in the winter was lower in Springsure koalas compared to those from Victoria. Feeding rates were discovered to be higher in the winter compared to summer.

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Category: Digestion, nutrition & metabolism

Selective medium for enumeration of tannin-protein complex-degrading Streptococcus spp. in faeces of koalas

Osawa, RO & Mitsuoka, T 1990, Applied and Environmental Microbiology, vol. 56, no. 11, pp. 3609-3611.

The authors of this study developed a selective agar plate medium that can successfully enumerate strains of tannin-protein complex-degrading Streptococcus bovis bacteria in faecal samples from koalas.

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Category: Infection & disease

Serological assessment of chlamydial infection in the koala by a slide EIA technique

Ueno, H, Mizuno, S, Takashima, I, Osawa, R, Blanshard, W, Timms, P, White, N & Hashimoto, N 1991, Australian Veterinary Journal, vol. 68, no. 12, pp. 393-396.

A slide enzyme immunosorbent assay (EIA) that can reliably detect Chlamydia psittaci antibody in koala blood serum is described in this study, presenting a rapid, simple and reliable alternative to existing methods.

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Category: Life history

Sexual maturity, factors affecting the breeding season and breeding in consecutive seasons in populations of overabundant Victorian koalas (Phascolarctos cinereus)

McLean, N & Handasyde, KA 2006, Australian Journal of Zoology, vol. 52, pp. 385-392.

At sexual maturity, female koalas in Victorian koala populations had an average age of 24.4 months, head length of 125 mm and body mass of 6.6 kg. The length and timing of the breeding season differed significantly between the island populations and inland populations, with those in island populations commencing earlier and lasting longer than those in inland populations.  More male offspring were born earlier in the breeding season than females, and Chlamydia appeared to affect the frequency of breeding in consecutive seasons.

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Category: Infection & disease

Skeletal fluorosis in marsupials: a comparison of bone lesions in six species from an Australian industrial site

Death, C, Coulson, G, Kierdorf, U, Kierdorf, H, Ploeg, R, Firestone, SM, Dohoo, I & Hufschmid, J 2017, Science of the Total Environment, vol. 584-585, no. 1, pp. 1198-1211.

Koalas and other marsupials living in high-fluoride environments are at risk of developing skeletal fluorosis. The severity of skeletal lesions in an affected animal is positively associated with bone fluoride levels. Of the six species studied here, all exhibited either localised or generalised periosteal hyperostosis but the distribution of lesions varied according to the animal’s mastication and gait.

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Category: Digestion, nutrition & metabolism

Spectrometric prediction of secondary metabolites and nitrogen in fresh Eucalyptus foliage: towards remote sensing of the nutritional quality of foliage for leaf-eating marsupials

Ebbers, MJH, Wallis, IR, Dury, S, Floyd, R & Foley, WJ  2002, Australian Journal of Botany, vol. 50, no. 1, pp. 761-768.

Near-infrared reflectance spectroscopy was used to obtain spectra from whole fresh and dry leaves for E. melliodora and E. globulus, two common Eucalyptus species, to determine concentration of total nitrogen, 1,8 cineole (a terpene) and sideroxylonal A (a phenolic antifeedant compound). This technique was successful, with the water absorbance peaks not obscuring the peaks on 1,8 cineole’s spectrum and obscuring some non-vital peaks on nitrogen and sideroxylonal A’s spectra, meaning that their concentrations could be reliably predicted. The concentrations for E. globulus were less accurate than for E. melliodora, likely due to wax on the leaf surface interfering in the experiment.

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Category: Anatomy & physiology

Sperm membrane fatty acid composition in the Eastern grey kangaroo (Macropus giganteus), koala (Phascolarctos cinereus), and common wombat (Vombatus ursinus) and its relationship to cold shock injury and cryopreservation success

Miller, RR Jr, Sheffer, CJ, Cornett, CL, McClean, R, MacCallum, C & Johnston, SD 2004, Cryobiology, vol. 49, no. 1, pp. 137-148.

Koala cauda epididymidal spermatozoa have low membrane cholesterol levels and a high ratio of unsaturated/saturated membrane fatty acids compared to other studied species, including other marsupials. In particular, docosahexaenoic acid (DHA), a long-chain polyunsaturated fatty acid and the most predominant membrane fatty acid in the studied marsupial species, was found in high levels in koala spermatozoa and is thought to be related to its cryogenic tolerance.

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Category: Infection & disease

Streptobacillary pleuritis in a koala (Phascolarctos cinereus)

Russell, EG & Straube, EF 1979, Journal of wildlife Diseases, vol. 15, no. 3, pp. 391-394.

Streptobacillus moniliformis pleuritis was observed in a koala. There were granulomatous lesions observed, which occur when the immune system of an animal walls off foreign substances with macrophages due to being unable to eliminate the substance. A culture was made and inoculated in mice and rats, with the organism determined to be pathogenic for mice but not rats.

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Category: Life history

Studies of the oestrous cycle, oestrus and pregnancy in the koala (Phascolarctos cinereus)

Johnston, SD, McGowan, MR, O’Callaghan, PO, Cox, R & Nicolson, V 2000, Journal of Reproduction and Fertility, vol. 120, no. 1, pp. 49-57.

This study described the oestrous cycles of both non-mated and mated female koalas in terms of relationships between oestrus, oestrous behaviours, the appearance of the external genitalia, and concentrations of the reproductive steroids oestradiol and progestogen.

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Category: Anatomy & physiology

Surface enlargement in the large intestine of the koala (Phascolarctos cinereus): morphometric parameters

Snipes, RL, Snipes, H & Carrick, FN 1993, Australian Journal of Zoology, vol. 41, pp. 393-397.

Multiple parameters of the morphology of the koala’s large intestine were measured. A computer-aided planimeter was used to find the basal surface area of the caecum and colon, and the microscopically visible folds/plicae were measured to determine the surface enlargement of the mucosa. The basal surface areas were 890.6 cm2 for the caecum (32.0% of the entire intestine), 1434.8 cm2 for the colon (51.5%) and the entire intestine was 2785.0 cm2. An average of 8 and 12-14 longitudinal folds were found striping the caecum and proximal colon, respectively, which increased the surface area significantly. The surface areas for the caecum, colon and entire intestine, respectively, when including the extra surface from the folds were 3659.8 cm2 (45.9%), 3854.0 cm2 (48.3%) and 7973.4 cm2. Respective total surface areas were determined by multiplying the basal surface area by the surface enlargement factor. These were 10,979.5 cm2 (44.9%), 9808.5 cm2 (40.1%) and 24,464.7 cm2 for the caecum, colon and entire intestine, respectively.

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Category: Digestion, nutrition & metabolism

Tannin-protein complex-degrading enterobacteria isolated from the alimentary tracts of koalas and a selective medium for their enumeration

Osawa, RO 1992, Applied and Environmental Microbiology, vol. 58, no. 5, pp. 1754-1759.

Strains of tannin-protein complex degrading (T-PCD) bacteria were identified in the faeces and caecum of the koala. These enterobacteria were facultatively anaerobic, gram-negative, pleomorphic, nonmotile bacilli, which are characteristics indicating that the strains fell within the Enterobacteriaceae family. All strains formed distinctly separate colonies after incubation on a tannin-treated agar plate and were also resistant to the antibiotic vancomycin. These characteristics informed the development of a selective agar plate medium that could be used to isolate and identify T-PCD enterobacteria from koala faeces while simultaneously restricting the growth of the common T-PCD bacterium Streptococcus bovis.

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Category: Digestion, nutrition & metabolism

Testosterone dehydrogenase activity in koala liver: characterisation of cofactor and steroid substrate differences

Stupans, I, Kong, S, Kirlich, A, McKinnon, RA & Murray, M 2000, Comparative Biochemistry and Physiology, part C, pp. 245-250.

The activity of testosterone dehydrogenase, or 17b-HSD, in the liver was evaluated in koalas, tammar wallabies, rats and humans. The activity was higher in koalas than wallabies, but was similar when NAD, an enzyme cofactor, was used in assays. Enzyme kinetics showed testosterone dehydrogenase mostly uses NADP as a cofactor in the liver of the koala, and that this pathway is utilised to a lesser extent in wallabies, human and rats than it is in koalas.

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Category: Genetics

The dynamic interplay between genomic DNA and the outside world

Leitch, AR 2007, Heredity, vol. 98, pp. 61 – 62.

Exposure to the external environment has resulted in dynamic changes in the eukaryote genome, at a scale which has only recently been understood. In 2006, Tarlinton and colleagues postulated that the integration of a retrovirus into the koala genome occurred only within the last 100 years, which has led to retroviral endogenisation of some koala populations across Australia. This model provides further evidence that dynamism within the genome can be affected by the extra-genomic environment.

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Category: Evolution

The marsupial mitochondrial genome and the evolution of placental mammals

Janke, A, Feldmaier-Fuchs, G, Thomas, WK, von Haeseler, A & Pӓӓbo, S 1994, Genetics, vol. 137, no. 1, pp. 243-256.

The entire mitochondrial genome of the American opossum, Didelphis vinginiana, was sequenced here and its distinguishing features described. A phylogenetic tree was created from the genetic sequence which demonstrated that rodents formed an earlier mammalian branch than did primates. The rate of evolution of the mitochondrial genome is clocklike, and this knowledge combined with genetic data indicated that the mouse and rat diverged as long as 35 million years ago.

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Category: Infection & disease

The nucleotide sequence of koala (Phascolarctos cinereus) retrovirus: a novel type C endogenous virus related to gibbon ape leukaemia virus

Hanger, JJ, Bromham, LD, McKee, JJ, O’Brien, TM & Robinson, WF 2000, Journal of Virology, vol. 74, no. 9, pp. 4264-4272.

For the first time, the full nucleotide sequence of koala retrovirus (KoRV) is reported and characterised as a novel C-type endogenous retrovirus as a result. Phylogenetic analyses revealed a close genetic relationship between KoRV and gibbon ape leukaemia virus (GALV).

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Category: Genetics

The nucleotide sequence of koala (Phascolarctos cinereus) retrovirus: a novel type C endogenous virus related to gibbon ape leukaemia virus

Hanger, JJ, Bromham, LD, McKee, JJ, O’Brien, TM & Robinson, WF 2000, Journal of Virology, vol. 74, no. 9, pp. 4264-4272.

For the first time, the full nucleotide sequence of koala retrovirus (KoRV) is reported and characterised as a novel C-type endogenous retrovirus as a result. Phylogenetic analyses revealed a close genetic relationship between KoRV and gibbon ape leukaemia virus (GALV).

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Category: Anatomy & physiology

The structural organisation of sperm head components of the wombat and koala (suborder: Vombatiformes): an enigma amongst marsupials

Breed, WG, Leigh, CM & Ricci, M 2001, Journal of Anatomy, vol. 198, pp. 57-66.

Despite many similarities in sperm head morphology, the organisational structure of chromatin was found to differ between koala and wombat sperm; inferring that these structures are species-specific, a finding not previously described in any study.

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Category: Digestion, nutrition & metabolism

The use of faecal cuticle examination to determine the dietary composition of koalas

Ellis, W, Carrick, F, Lundgren, P, Veary, A & Cohen, B 1999, Australian Zoologist, vol. 31, no. 1, pp. 127-133.

Eucalyptus leaves ingested by captive koalas were present in faecal pellets up to 154 hours after consumption. Dietary composition examination utilising the ‘faecal cuticle analysis’ technique was deemed an appropriate method to identify and estimate quantities of different Eucalyptus spp. in a koala’s diet.

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Category: Infection & disease

Time-delayed influence of urban landscape change on the susceptibility of koalas to chlamydiosis

McAlpine, C, Brearley, G, Rhodes, J, Bradley, A, Baxter, G, Seabrook, L, Lunney, D, Liu, Y, Cottin, M, Smith, AG & Timms, P 2017, Landscape Ecology, vol. 32, no. 3, pp. 1-17.

The effects of changes in landscape or climate on the prevalence of chlamydiosis in koalas may not manifest until several years after the initial change occurred. Disease prevalence and body condition of koalas in southeast Queensland were quantified to determine both the spatial factors that affect these variables and the time delay, if any, of the effect. For landscapes in which the area of suitable habitat increased, koalas had high body condition scores but also high disease prevalence three years later. Alternatively, when the extent of urbanisation in a landscape increased, koala populations exhibited an increased prevalence of chlamydiosis four years later and decreased body condition one year later. An increase in annual rainfall was associated with immediately improved body condition and reduced disease prevalence after two years.

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Category: Infection & disease

Transspecies transmission of gammaretroviruses and the origin of the gibbon ape leukaemia virus (GaLV) and the koala retrovirus (KoRV)

Denner, J 2016, Viruses, vol. 8, no. 12, 336.

Koala retrovirus (KoRV) is closely related to gibbon ape leukaemia virus (GALV), and it is thought that they both originate from transspecies transmissions from the same host. Bats are discussed as a possible host of a retrovirus transmitted to gibbons and koalas as they could feasibly enter both gibbon habitats in Thailand and koala habitats in Australia and also carry several endogenous and exogenous retroviruses.

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Category: Genetics

Transspecies transmission of gammaretroviruses and the origin of the gibbon ape leukaemia virus (GaLV) and the koala retrovirus (KoRV)

Denner, J 2016, Viruses, vol. 8, no. 12, 336.

Koala retrovirus (KoRV) is closely related to gibbon ape leukaemia virus (GALV), and it is thought that they both originate from transspecies transmissions from the same host. Bats are discussed as a possible host of a retrovirus transmitted to gibbons and koalas as they could feasibly enter both gibbon habitats in Thailand and koala habitats in Australia and also carry several endogenous and exogenous retroviruses.

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Category: Infection & disease

Use of quantitative real-time PCR to monitor the shedding and treatment of chlamydiae in the koala (Phascolarctos cinereus)

Markey, B, Wan, C, Hanger, J, Phillips, C & Timms P 2007, Veterinary Microbiology, vol. 120, no. 1, pp. 334-342.

A quantitative real-time analysis revealed that antibiotic treatment for koalas with chlamydial infections caused chlamydiae to shed rapidly and in great numbers from both ocular and urogenital sites, with the majority of infections cleared after two weeks of treatment.

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Category: Digestion, nutrition & metabolism

Variation in koala microbiomes within and between individuals: effect of body region and captivity status

Alfano, N, Courtiol, A, Vielgrader, H, Timms, P, Roca, AL & Greenwood, AD 2015, Nature: Scientific Reports, vol. 5, no. 10189.

Sequencing microbes’ 16S ribosomal RNA (rRNA) directly from the sample without culture is an accurate way to assess the relationship between the microbe and the host. The bacterial community, or the microbiome, in the eyes and digestive system of the koala were evaluated here. Captive koala microbiomes mostly resembled those of other animals and wild koalas. Unexpectedly, the microbiome of the koala eye contained many bacteria belonging to the Phyllobacteriaceae family.

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Category: Anatomy & physiology

Variation in reproductive parameters in the captive male koala (Phascolarctos cinereus)

Cleva, GM, Stone, GM & Dickens, RK 1994, Reproduction, Fertility and Development, vol. 6, pp. 713-719.

The concentration of plasma androgens was measured in six male koalas of sexually mature age (3-10 years) over a period of 23 months. Four of these koalas were situated away from females, while two were housed with females. The concentration of androgens appeared to change seasonally, with the lowest levels observed mid-year, and increased steadily coming into the beginning of breeding season. Males living in female presence had higher androgen concentrations, even without females being in oestrus. These androgen concentration changes did not correlate with any changes in volume of the testicles.

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Category: Digestion, nutrition & metabolism

Visual reading method for detection of bacterial tannase

Osawa, R & Walsh, TP 1993, Applied and Environmental Microbiology, vol. 59, no. 4, pp. 1251-1252.

The authors of this study develop and describe a new visual reading method for detecting the presence of tannase in cultures of bacteria that can degrade the tannin-protein complexes present in eucalypts, the main food source for the koala.

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Category: Infection & disease

Wasting disease in the koala, Phascolarctos Cinereus

Degabriele, R 1989, Perspectives in Biology and Medicine, vol. 32, no. 3, pp. 414-418.

This article provides a hypothesis for wasting disease in koalas. Some symptoms of wasting disease are weight loss and death in a coma with no indication of infection. Wasting disease is most common among very young, old and weak koalas, and particularly during winter or after droughts. In addition, a full stomach is often seen to accompany wasting disease.

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Category: Infection & disease

Within-population diversity of koala Chlamydophila pecorum at ompA VD1-VD3 and the ORF663 hypothetical gene

Higgins, DP, Beninati, T, Meek, M, Irish, J & Griffith, JE 2012, Veterinary Microbiology, vol. 156, pp. 353-358.

Chlamydophila pecorum is a bacterium that commonly infects koalas. This study evaluated the diversity of ompA VD1-3 gene and ORF663, a hypothetical gene, in koalas with chlamydia.

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