Microbiota characterisation in the Tasmanian devil
The Tasmanian devil (Sarcophilus harrisii), the world’s largest remaining carnivorous marsupial, faces extinction due to the spread of a contagious cancer called Devil Facial Tumour Disease (DFTD). The lack of a description of the bacterial community composition in the species represents a major gap in our knowledge of Tasmanian devil biology. In this study we characterised 12 microbiomes from four body sites, including mouth, gut, skin and pouch, in five Tasmanian devils via PCR amplification of 16S rRNA gene V1-V3 regions followed by 454 sequencing. A total of 249,224 reads with an average sequence length of 489 bp were obtained after length and quality filtering. The reads further clustered into 14533 operational taxonomic units (OTUs; sequence identity cutoff of >97%) that were classified to 24 phyla spanning 275 families. Higher levels of bacterial species richness were observed in the pouch and skin than in the mouth and gut. The pouch and skin showed similar microflora compositions, which may vary between animals, possibly due to different environments. Distinct from the previously reported koala gut microbiota , which is dominated by Bacteroidetes and Firmicutes, the devil gut microbiota was found to be dominated by Fusobacteria, Firmicutes and Proteobacteria, comprising up to 73.7-94.3% of the community. This study has greatly improved our understanding of the microbial communities in the Tasmanian devil, which will significantly contribute to the effort to conserve the species.
Cathelicidins in the Tasmanian devil (Sarcophilus harrisii)
Antimicrobial resistance is increasing, posing a threat to human and animal health. A lack of new antibiotics means alternatives such as antimicrobial peptides are urgently required. Antimicrobial peptides are a primitive component of the innate immune system. Cathelicidins are a predominant family within mammals, contributing to host immunity through antimicrobial and immunomodulatory functions. They have been studied extensively in eutherian mammals but marsupials are relatively unexplored. Marsupials give birth to altricial young which are immunologically naïve. During development the young are protected from infection by mechanisms such as cathelicidins within the pouch. This unique reproductive physiology has encouraged lineage specific expansion of the cathelicidin gene family within marsupials, resulting in numerous diverse peptides.
The Tasmanian devil (Sarcophilus harrisii) is the largest remaining carnivorous marsupial and is currently under threat from a contagious cancer, devil facial tumour disease (DFTD). Human and bovine cathelicidins exhibit anti-tumour activity against a number of cancers. Furthermore, studies in the tammar wallaby have revealed the potency of marsupial cathelicidins against multi-drug resistant bacteria. As such, release of the Tasmanian devil genome in 2012 provides new avenues in the search for cathelicidins with the therapeutic potential to treat DFTD and resistant pathogens.
We identified 7 cathelicidins in the Tasmanian devil genome which were highly variable and distantly related to eutherian cathelicidins. Six Tasmanian devil cathelicidins have been synthesised and will be tested against a range of bacteria and fungi. Preliminary antifungal testing of two cathelicidins revealed that one peptide was more effective at killing Candida krusei, Candida parapsilosis, Cryptococcus gattii and Cryptococcus neoformans than the antifungal drug fluconazole. Cytotoxic and haemolytic activity of all six cathelicidins has also been determined. Four cathelicidins did not kill human lung epithelial cells or red blood cells, and only two showed moderate cytotoxic and haemolytic activity. This study highlights the potential for marsupials such as the Tasmanian devil to provide new drugs to treat human and animal disease.
Animating the Gut Microbiome
Animation can be a powerful way to inspire and educate people with science. Creating biomedical animations which depict advanced scientific concepts in a clear way requires 2 main considerations, 1) rigorous investigation of the underlying science, and 2) careful development of the story to express the ideas in a meaningful way.
In this talk Christopher Hammang will present his first biomedical animation “The Hungry Microbiome”. He will explore the challenges involved in animating the human gut microbiome and the unique insight gained from creating an animation about resistant starch. The talk will also explore the workflow and technology which can be used to create these biomedical animations, as well as a brief review of the science underlying resistant starch research.
Evolution and function of marsupial gut microbiota
Despite growing interest in the form and function of mammalian gut microbiomes, few culture-independent studies have focused on the microbiomes of Australian marsupials. In particular, how do the microbiota of the koala and other toxic Eucalypt folivores enable these animals to occupy this specialised dietary niche? We are addressing this question by surveying the gut microbial communities of diprotodont marsupials across a range of phylogeny, diet, and gut morphology. Furthermore, beyond community profiles, we are probing community functionality through metagenome shotgun sequencing of the Vombatiformes (koala and wombat) gut microbiota. Using differential coverage binning and metabolic reconstruction, we have the comparative power to identify specialised pathways in koala and wombat microbiota, from the community-level down to the level of individual population genomes.