Honours Project Opportunities with Nate Lo

Project 1: Genome sequencing of the intracellular bacterium Midichloria mitochondrii.

Symbiotic bacteria have played a crucial role in animal evolution, allowing many lineages to invade new ecological niches. Midichloria mitochondrii is an intracellular bacterium found primarily in ticks. It is a member of the order Rickettsiales, which contains the closest living relatives of mitochondria, and includes primarily pathogenic genera such as Rickettsia, and primarily symbiotic genera such as Wolbachia. M. Mitochondrii is the only characterized bacterium able to invade the mitochondria of any multicellular organism. In this project you will use next generation sequencing to sequence the genome of a strain of M. Mitochondrii found in the Australian paralysis tick Ixodes holocyclus. The genome is estimated to be approximately 1 million base pairs in length. Phylogenomic comparisons will then be made with a strain present in the European tick Ixodes ricinus, as well as other Rickettsiales. This will increase our understanding of the origins of mitochondria, and Midichloria’s unique ability to invade these organelles.

Project 2: Gender bending Wolbachia parasites in termites

Wolbachia is a genus intracellular bacteria estimated to be present in more than 50% of arthropods, making it the most widespread parasite on earth. These bacteria cause a variety of remarkable reproductive manipulations to their hosts, including male-killing, feminization of genetic males, parthenogenesis and cytoplasmic incompatibility. Wolbachia are also found in filarial nematodes, where they act as obligate mutualists. This wide range of host-interactions - as well as their potential for novel approaches to pest control and fighting diseases such as malaria, river blindness and elephantitis - has led to an explosion of interest in these bacteria in recent years.

This project will investigate a novel lineage of Wolbachia found in termites, which are social insects of considerable economic importance in Australia. Molecular techniques will be used to examine how these bacteria are distributed within termite individuals, colonies and populations. Like males in general, sterile workers in social insect colonies represent a “dead-end” to Wolbachia. Is the bacterium more likely to be found in reproducing individuals? Or, does the bacterium’s presence in foraging workers enhance its horizontal transmission? Have particular Wolbachia strains swept quickly through termite populations, carrying mitochondria with them, as has been found for mosquitoes and flies? To address these questions, molecular markers, population genetic and phylogenetic methods will be employed.