Red-tailed phascogales: A review of their biology and importance as model marsupial species

There are many limitations when using traditional laboratory species. Limits on variation, may result in limited outcomes, at both the species and individual level, due to different individuals/species having diverse physiological processes, or differing molecular and genetic mechanisms. By using a variety of model species, we will be able to develop creative solutions to biological problems and identify differences of which we were not previously aware. The laboratory mouse has been a suitable model species for various mammalian studies, however most are bred specifically for laboratory research with limited variability due to selective breeding. Marsupial models offer unique research opportunities compared to eutherian models. We believe that there should be an expansion in marsupial model species, and the introduction of the red-tailed phascogale (Phascogale calura), a dasyurid marsupial, should be one of them. Phascogales are easily managed in captivity, and there are now multiple studies involving their development, reproduction, nutrition, behavior and immune system, which can serve as a baseline for future studies. The addition of the phascogale as a model species will improve future mammalian studies by introducing variability and offer alternate solutions to biological problems, particularly in the areas of genetics, nutrition, immunology, the neuro-endocrine system, and ageing, due to their semelparous reproductive strategy and hence, subsequent predictive physiology. In this review, we provide information based on existing research on red-tailed phascogales to support their inclusion as a model species.

MHC Class II variability in bare-nosed wombats (Vombatus ursinus)

Studies of gene diversity are used to investigate population dynamics, including immunological fitness. Aside from the selection of an appropriate gene target, an important factor that underpins these studies is the ability to recover viable DNA samples from native animals that are protected, threatened or difficult to sample or locate such as the bare-nosed wombat (Vombatus ursinus). In this study, we used genomic DNA extracted from muscle tissue samples and also identified the optimal method to extract DNA from fresh wombat scat samples to enable further analyses to be performed using non-invasive techniques. The DNA was probed via the polymerase chain reaction using previously targeted marsupial Major Histocompatibility Complex (MHC) gene primers. These genes are highly variable and associated with binding and presentation of pathogens in the immune system. Twenty-three unique MHC Class II DAB V. ursinus gene sequences were translated to 21 unique predicted peptide sequences from 34 individual tissue or scat samples. Vombatus ursinus MHC Class II DAB gene and peptide sequences were most similar to other marsupial DNA and peptide sequences. Further analysis also indicated the likelihood of MHC Class II DAB family membership through motif identification. Additional sampling is required to assess the full level of diversity of MHC Class II DAB genes among V. ursinus populations; however, this study is the first to identify MHC genes in a wombat and will advance immunological and disease studies of the species.

Limitations in the isolation and stimulation of splenic mononuclear cells in a dasyurid marsupial, Phascogale calura

OBJECTIVE

Marsupials suffer from an increasing number of stressors in this changing world. Functional studies are thus needed to broaden our understanding of the marsupial immune system. The red-tailed phascogale (Phascogale calura) is a small Australian marsupial previously used in descriptive immunological studies. Here, we aimed to develop functional assays by isolating and stimulating blood and spleen mononuclear cells in vitro.

RESULTS

While peripheral blood mononuclear cell (PBMC) were relatively easy to isolate, only 105 mononuclear cells (> 90% purity and > 75% viability) could be recovered from the spleen, independently of the sex and age of the animal or the centrifugation time and speed tested. The pores of the mesh sieve used for tissue homogenization might have been too big to yield a single cell suspension. Nevertheless, in spite of the overall low number of cells recovered, PBMC and splenic mononuclear cells were successfully activated in preliminary trials with phytohemaglutinin. This activation state was evidenced by a change in shape and the presence of small cell aggregations in the mitogen-stimulated cultures. A non-radioactive colorimetric assay was also performed to confirm cell proliferation in these wells. This work highlights the importance of developing and reporting detailed methodological protocols in non-traditional research species.

Sarcoptic mange in wombats-A review and future research directions

Sarcoptic mange is caused by the mite Sarcoptes scabiei and has recently been recognized as an emerging infectious disease of wildlife worldwide. The mite is one of the main causes of population decline in southern hairy-nosed (Lasiorhinus latifrons) and bare-nosed wombats (Vombatus ursinus). This review focuses on Sarcoptes scabiei infestations in wombats and provides insights into why the disease may be so prevalent in wombats. Current treatment practices and trials conducted in the field to reduce the incidence of sarcoptic mange in wombats are described and critically reviewed. Current and potential future avenues of research are discussed.