Davies N.,University of Queensland |
Gillett A.,Australia Zoo Wildlife Hospital |
McAlpine C.,University of Queensland |
Seabrook L.,University of Queensland |
And 4 more authors.
Journal of Endocrinology | Year: 2013
Environmental changes result in physiological responses of organisms, which can adversely affect population dynamics and reduce resistance to disease. These changes are expressed in chronic levels of stress. The measurement of glucocorticoid (GC) concentrations in faeces is a non-invasive method for monitoring stress in wildlife. The metabolism and excretion of steroids differ significantly between species and, as a consequence, non-invasive methods must be physiologically validated for each species. Koalas (Phascolarctos cinereus) are declining in numbers through much of their range. The role of chronic stress in koala populations has not been identified. Prior to the assessment of faecal GC concentrations in wild koala populations, the excretion timing and concentrations of GCs need to be determined. In this study, we assessed a method for identifying and measuring the concentrations of GC metabolites in faecal pellets of captive koalas following ACTH treatment. The results show that an elevation of plasma cortisol concentrations, using sustained release of ACTH, results in elevated concentrations of faecal cortisol/cortisol metabolites. Taking into account the excretion time lag, an increase in faecal cortisol metabolite concentrations corresponds to the release of GCs from the adrenal cortex as early as 36 h before faecal pellet collection. The calculations of steroid partitioning of plasma cortisol showed that the ACTH-stimulated values were significantly different from the control values for the concentrations of free, corticosteroid-binding globulin-bound and albumin-bound cortisol. This study validates the use of faecal cortisol analysis to assess the activity of the hypothalamo-pituitary-adrenocortical axis in freshly collected koala faecal pellets and indicates that the method should be suitable to assess the adrenocortical status of koalas in wild populations. © 2013 Society for Endocrinology.
Waugh C.,University of The Sunshine Coast |
Gillett A.,Australia Zoo Wildlife Hospital |
Polkinghorne A.,University of The Sunshine Coast |
Timms P.,University of The Sunshine Coast
Journal of Wildlife Diseases | Year: 2016
Little is known about the immune response in the koala (Phascolarctos cinereus) to its retroviruses. Koala retroviruses (KoRVs) have been linked to neoplasia in wild and captive koalas, but there is no treatment available. We tested the KoRV-specific serum immunoglobulin G antibody response in nonimmunized and immunized koalas. © Wildlife Disease Association 2016.
Hobbs M.,Australian Museum Research Institute |
Pavasovic A.,Queensland University of Technology |
King A.G.,Australian Museum Research Institute |
Prentis P.J.,Queensland University of Technology |
And 12 more authors.
BMC Genomics | Year: 2014
Background: The koala, Phascolarctos cinereus, is a biologically unique and evolutionarily distinct Australian arboreal marsupial. The goal of this study was to sequence the transcriptome from several tissues of two geographically separate koalas, and to create the first comprehensive catalog of annotated transcripts for this species, enabling detailed analysis of the unique attributes of this threatened native marsupial, including infection by the koala retrovirus. Results: RNA-Seq data was generated from a range of tissues from one male and one female koala and assembled de novo into transcripts using Velvet-Oases. Transcript abundance in each tissue was estimated. Transcripts were searched for likely protein-coding regions and a non-redundant set of 117,563 putative protein sequences was produced. In similarity searches there were 84,907 (72%) sequences that aligned to at least one sequence in the NCBI nr protein database. The best alignments were to sequences from other marsupials. After applying a reciprocal best hit requirement of koala sequences to those from tammar wallaby, Tasmanian devil and the gray short-tailed opossum, we estimate that our transcriptome dataset represents approximately 15,000 koala genes. The marsupial alignment information was used to look for potential gene duplications and we report evidence for copy number expansion of the alpha amylase gene, and of an aldehyde reductase gene. Koala retrovirus (KoRV) transcripts were detected in the transcriptomes. These were analysed in detail and the structure of the spliced envelope gene transcript was determined. There was appreciable sequence diversity within KoRV, with 233 sites in the KoRV genome showing small insertions/deletions or single nucleotide polymorphisms. Both koalas had sequences from the KoRV-A subtype, but the male koala transcriptome has, in addition, sequences more closely related to the KoRV-B subtype. This is the first report of a KoRV-B-like sequence in a wild population. Conclusions: This transcriptomic dataset is a useful resource for molecular genetic studies of the koala, for evolutionary genetic studies of marsupials, for validation and annotation of the koala genome sequence, and for investigation of koala retrovirus. Annotated transcripts can be browsed and queried at http://koalagenome.org. © 2014 Hobbs et al.; licensee BioMed Central Ltd.
Bachmann N.L.,University of The Sunshine Coast |
Fraser T.A.,Queensland University of Technology |
Bertelli C.,Queensland University of Technology |
Bertelli C.,Swiss Institute of Bioinformatics |
And 10 more authors.
BMC Genomics | Year: 2014
Background: Chlamydia pecorum is an important pathogen of domesticated livestock including sheep, cattle and pigs. This pathogen is also a key factor in the decline of the koala in Australia. We sequenced the genomes of three koala C. pecorum strains, isolated from the urogenital tracts and conjunctiva of diseased koalas. The genome of the C. pecorum VR629 (IPA) strain, isolated from a sheep with polyarthritis, was also sequenced.Results: Comparisons of the draft C. pecorum genomes against the complete genomes of livestock C. pecorum isolates revealed that these strains have a conserved gene content and order, sharing a nucleotide sequence similarity > 98%. Single nucleotide polymorphisms (SNPs) appear to be key factors in understanding the adaptive process. Two regions of the chromosome were found to be accumulating a large number of SNPs within the koala strains. These regions include the Chlamydia plasticity zone, which contains two cytotoxin genes (toxA and toxB), and a 77 kbp region that codes for putative type III effector proteins. In one koala strain (MC/MarsBar), the toxB gene was truncated by a premature stop codon but is full-length in IPTaLE and DBDeUG. Another five pseudogenes were also identified, two unique to the urogenital strains C. pecorum MC/MarsBar and C. pecorum DBDeUG, respectively, while three were unique to the koala C. pecorum conjunctival isolate IPTaLE. An examination of the distribution of these pseudogenes in C. pecorum strains from a variety of koala populations, alongside a number of sheep and cattle C. pecorum positive samples from Australian livestock, confirmed the presence of four predicted pseudogenes in koala C. pecorum clinical samples. Consistent with our genomics analyses, none of these pseudogenes were observed in the livestock C. pecorum samples examined. Interestingly, three SNPs resulting in pseudogenes identified in the IPTaLE isolate were not found in any other C. pecorum strain analysed, raising questions over the origin of these point mutations.Conclusions: The genomic data revealed that variation between C. pecorum strains were mainly due to the accumulation of SNPs, some of which cause gene inactivation. The identification of these genetic differences will provide the basis for further studies to understand the biology and evolution of this important animal pathogen. © 2014 Bachmann et al.; licensee BioMed Central Ltd.
The painful and intractable disease is having a devastating impact on populations of Australia's beloved marsupial. Specialist koala vets are using two antibiotics – Baytril and Chloramphenicol 150. However, there is less than two years' supply of Chloramphenicol 150 remaining and the drug is no longer on the market. Neither of the current treatments works in all cases of chlamydial disease and a new treatment is urgently needed. Microbiologist Dr Willa Huston, of the University of Technology Sydney, with collaborators at Australia Zoo Wildlife Hospital and elsewhere, has identified a chemical that paves the way for a new antibiotic to save koalas' lives. In extensive laboratory tests on tissue samples from chlamydia-infected koalas, the researchers found the compound to be highly successful at killing the bacteria and low in toxicity against koala cells. "It's really urgent now that we put a concerted effort into developing this treatment further," says Dr Huston. "Manufacture [of the old one] has stopped, supply has stopped, and it can take years to develop a new drug. "We are in a desperate search to find new, effective treatments and test other drugs that might help koalas recover from this horrible disease." Koalas are listed as a vulnerable species in NSW and Queensland. Fewer than 100,000 remain in the wild in Australia and are at risk from habitat loss, motor vehicle trauma, domestic dog attacks and, increasingly, disease. Dr Huston says as many as one in five koalas in the wild in south-east Queensland and northern NSW have severe chlamydiosis; some studies have found as many as nine in 10 koalas with chlamydial infections. Wildlife veterinarians are also reporting that the disease is spreading south – infections have been reported in Victoria, where koala populations are larger, and South Australia, where koalas are listed as "rare". Male and female koalas are affected by two species of Chlamydia – C. pecorum and C. pneumoniae. The first causes eye disease, including inflammation and discharge, or urogenital disease, including cystitis, urinary incontinence (known as "wet bottom") and fibrosis, which can cause infertility. The second strain causes severe respiratory illness. Any new drug must be able to treat chlamydiosis while minimising side effects. As a specialised eucalyptus herbivore, the koala's metabolism is uniquely placed to deal with toxic plant compounds. However, koalas respond poorly to antibiotic treatments commonly used in humans, suffering side effects such as emaciation, and typically fail to recover completely from disease. Dr Huston and her team are fine-tuning the chemical make-up of their discovery before they begin testing on sick koalas. "Time is running out. We all treasure our koalas and we need to do everything we can to cure this disease." The paper is published in the Nature journal Scientific Reports. More information: Amba Lawrence et al. Chlamydia Serine Protease Inhibitor, targeting HtrA, as a New Treatment for Koala Chlamydia infection, Scientific Reports (2016). DOI: 10.1038/srep31466