Charlotte Oskam

Piroplasms belonging to genera Theileria and Babesia (Phylum: Apicomplexa) are vector-borne protozoan haemoparasites with similar phenotype that infect erythrocytes of domesticated mammals and wildlife including birds. In addition, piroplasms of Theileria have an exoerythrocytic life cycle stage within the host’s white blood cells. Observations of intraerythrocytic piroplasms have been made sporadically in peripheral blood films of Australian native mammals since the first report was made nearly a Century ago and the advent of PCR has stimulated renewed research interest and descriptions of the molecular phylogeny of these organisms in a variety of marsupial hosts. A piroplasm (Theileria ornithorhynchi) has been described in previous studies of the platypus (Ornithorhynchus anatinus). As part of a study into the health and ecology of this iconic monotreme, blood samples were collected for haematological and biochemical analysis from wild-trapped platypuses in Tasmania. A subset of these samples, together with their ectoparasites, was evaluated for piroplasm infections by blood film microscopy and molecular analysis of the 18S ribosomal RNA gene, and phylogenetic analysis was performed with NJ trees using BIONJ. Estimates of evolutionary divergence between sequences were calculated by MEGA 5. A total of 27 blood samples and eight ectoparasites (seven ticks, one leech) were examined from 27 platypuses. All ticks were identified as Ixodes ornithorhynchi. Piroplasm infections were highly prevalent in the population studied (27/27; 100% infected); organisms were pleomorphic with infrequent tetrads and intra-leukocytic forms, thought to be Theileria schizonts, were occasionally observed. Anaemia was not detected. Many platypuses were co-infected with trypanosomes. All blood samples and three ectoparasites were positive for piroplasm DNA and phylogenetic analysis suggested the presence of more than one piroplasm species. This study emphasises the importance of combining traditional parasitological techniques (e.g. microscopy and tick examination) with molecular techniques if the life cycle of organism is to be understood.

The genetic information preserved in fossil bone, eggshell, museum skins and sediments can provide a direct window into the past. This presentation will showcase recent research projects involving bettongs, cockatoo’s and the extinct New Zealand moa. In the target species both mitochondrial and nuclear DNA has been analysed using Bayesian techniques to infer relationships and demography in a temporal and spatial context. In each of these examples ancient DNA provides some key insights into the level of connectivity between populations, the impact of fragmentation and the degree to which genetic biodiversity has (or hasn’t) been lost. Lastly this presentation will examine how new (high-throughput) DNA sequencing technologies when applied to ancient sediments is emerging as a valuable tool in both palaeontological and archaeological research. Genetic ‘audits’ of plants, vertebrates and insects can be carried out (if there is DNA preservation) from only a few grams of dirt. These new approaches reveal a surprising about of detail about the composition of past ecosystems.