Honours Projects in the School of Biological Sciences 2006

Honours semester 1, 2006

	Gareth Andrews Co-supervised by Adele Pile and Steve Simpson The Effect of Physical Disturbance Associated with Deep-Sea Drilling on the Nutritional Ecology of Deep-Sea Scavengers Nutritional ecology focuses on the exchange of nutrients between individual organisms and their environment. In the deep-sea nutrient-rich food fall events are rare and unpredictable. This leads to the question of whether deep-sea scavengers have the luxury of selecting an optimal nutritionally-balanced diet and, if not, whether they are limited by particular nutrients. Such nutritional problems may be exacerbated by habitat disturbance, such as that occasioned by ocean drilling. This study will focus on the nutritional ecology of the deep-sea and also the impact that anthropogenic disturbance events have on deep-sea communities.
	Oliver Bradshaw Co-supervised by Clare McArthur and Adele Pile Effects of Wind and Nutrients on Plant Growth and the Consequences for Herbivory This project investigates a new novel concept, testing the chronic effects of wind and nutrients on plant growth and the effects on herbivory. This area of research is in its infancy and this project will fill a large gap in our knowledge base for terrestrial ecology. The project may also have some economic significance for the forestry industry in terms of inducing plant defence mechanisms against herbivory, thus reducing the need for chemical pesticides and baiting. This investigation will look at how wind changes chemical and physiological plant characteristics and how these changes subsequently affect herbivore feeding preferences.
	Neisha Burton Co-supervised by Keryn Perry-Jones and Glenda Wardle Foraging behaviour of the Grey-headed Flying-fox (Pteropus poliocephalus) from a colony at the Royal Botanic Gardens, Sydney The Grey-headed Flying-fox is classified as vulnerable under New South Wales and federal legislation, largely due to a decline in population. This is largely due to loss of habitat. Grey-headed Flying-foxes forage over a wide area with patchy resources and are important pollinators for the species they feed on. Knowledge of foraging sites and their importance, and population numbers will assist in managing this colony.
	Kevin Chen Co-supervised by Bruce Lyon and Alison Heather Anti-inflammatory properties of High Density Lipoproteins Metabolic syndrome is a major health issue today affecting on average one in four adults in America, greatly increasing their risk for type two diabetes and coronary artery disease.  The disease is caused by obesity and lack of exercise, which causes inflammation in the adipocyte and liver.  Inflammation in all cells are mediated by the transcription factor NFkB.  This project aims to investigate whether high density lipoproteins (good cholesterols) can suppress inflammation via the NFkB pathway.  This will provide a better understanding of the pathway of inflammation,  and more importantly provide a potential treatment for preventing not only metabolic syndrome, but diabetes and coronary artery diseases as well.
	Fiona Guan Co-supervised by Neville Firth and Slade Jensen Transcriptional Regulation of Staphylococcal Multiresistance Plasmid pSK41      Multidrug resistant Staphylococcus aureus are a major cause of nosocomial infections globally and commonly contain plasmids that carries the resistance genes. pSK41 is the  prototype of the conjugative multisresistance family of plasmids. Little is known on the regulations controlling the expression of genes encoding for the plasmid's essential functions. Project aims: to elucidate the extent of regulation a protein, ArtA, has on pSK41. ArtA was previously shown to regulate to regulate genes involved in the conjugative process. Understanding of such a coordinated regulation system may present opportunities to disrupt it, hence resistance plasmids (pSK41) are selectively disadvantaged.
	Michael Haung Co-supervised by Lars Jermiin and Michael Charleston How much codivergence is a lot? Current procedures for inferring cophylogeny have flaws in both conceptual design and statistical analyses. To explore these two areas, this project sets out to assess the application of an explicit model for recovery of cophylogeny, and to discover systematic differences between the reconstructed history and true history. The outcome of this project will redefine the process of cophylogenetic analyses such that it provides more accurate and reliable results, which will contribute to our fundamental understanding of coevolution.
	Joshua Ho Co-supervised by Lars Jermiin and Michael Charleston Assessing Limitations of Gene Regulatory Network Reconstruction Methods A Gene regulatory network (GRN) is an abstract model of gene-to-gene interactions. A number of computational methods can reconstruct GRNs from microarray data. Systematic and objective evaluation of these methods has not been undertaken so far. This project aims to devise a general framework for evaluating GRN reconstruction methods. Considering the dynamic nature of GRN and the large amount of experimental noise inccured in the microarray, the effect of network topology and experimental noise on reliability of GRN reconstruction is explored in this study. This project will shed light on improving current GRN reconstruction methods.
	Penny Ho Co-supervised by Ron Skurray and Melissa Brown Molecular analysis of TMS 5 of the staphylococcal QacA multidrug exporter The treatment of hospital acquired Staphylococcus aureus infections presents a serious problem worldwide, due to the development of multidrug resistant strains. The staphylococcal efflux protein QacA mediates resistance by the active extrusion of antimicrobial agents and recognises a broad range of structurally dissimilar compounds. Complete knowledge of the molecular structure and function of QacA remains to be delineated. This project will identify and characterise QacA amino acid residues important in drug binding, providing a deeper understanding of the structure-function relationships that govern its activity. This has applications in novel drug design and the improvement of current treatment strategies
	Danny Liu Co-supervised by Robyn Overall and David Day Intracellular and intercellular trafficking via the plant endomembrane system Plasmodesmata are minute channels that connect adjacent plant cells and allow intercellular flow of housekeeping molecules and developmental signals. They also provide a pathway for viral dissemination. Plasmodesmata are therefore crucial to the physiology, development and health of plants. This project aims to develop a novel strategy to investigate an essentially uncharacterised, endomembrane-based transport pathway to and through plasmodesmata. It will also examine the role of an uncharacterised protein thought to be involved in endomembrane trafficking. Identification and characterisation of a new transport continuum between plant cells would provide valuable insight into intercellular communication with potential horticultural and agricultural benefits.
	Maggie Ma Supervised by Murray Thomson Localization of steroidogenic proteins in human placental mitochondria Placental steroidogenesis is vital for endocrine control and the development of various organs in the foetus. Any disorder in the process of placental steroidogenesis will dramatically alter the foetus’ fate. In this project I will be focusing on the mechanism of the metabolic pathway of steroidogenesis, in particular, the first and rate-limiting step of steroidogenesis. We aim to localise several vital steroidogenic proteins involved in this first step, so that replacement of missing or damaged steroidogenic proteins will be allowed via gene therapy.
	Cindy Pon Co-supervised by Neville Firth and Stephen Kwong Functional Analysis of Replication Initiation in the Staphylococcal Multiresistance Plasmid pSK41 Strains of Staphylococcus aureus are a major cause of hospital acquired infections worldwide due to their ability to rapidly develop resistance to antimicrobial agents. These resistances are commonly mediated through multiresistance plasmids carried by these pathogens. However, little is known about the biology of these plasmids, particularly, the molecular details underlying their replication systems. It is important to understand plasmid replication as it is crucial to the survival of plasmids, and hence the maintenance of resistance. This project aims to examine the molecular basis of multiresistance plasmid replication initiation. Findings will enhance our understanding of how multiresistance plasmids replicate and maintain themselves in clinical environments.
	Chloe Sato Supervised by Chris Dickman Foraging Behaviour of Australian Desert Dunnarts The lesser hairy-footed dunnart (Sminthopsis youngsoni) has adapted well to arid environments, yet little is known about how this species functions at the level of individual. This study aims to identify the diet and foraging behaviours of S. youngsoni. This will highlight important microhabitats and food sources required by S. youngsoni for survival, particularly in times of food and water stress. Management and conservation of these habitats will ensure the future long term survival of S. youngsoni. These measures may become important in the future with the impact of greenhouse warming predicting that inland deserts will become hotter and more variable.
	Alex Schnell Co-supervised by Frank Seebacher and Mike Thompson Thermal sensitivity and potential distribution of the invasive tilapia, Oreochromis mossambicus The Mozambique mouth-brooder was illegally introduced into Australia in the 1970’s. Since its introduction it has dominated many warm freshwater habitats and as consequence displaced many native species. Numerous ectotherms, particularly fish are able to reversibly change their phenotype to compensate for changes in the environment, which allow them to perform over a large thermal interval. This study will focus on thermal acclimation as a response to changing temperature and in the process identify the species thermal optima and limits. Data can then be transformed into a spatial model representing the potential geographic distribution of the species.
	George  Sharbeen Co-supervised by Ron Skurray and Melissa Brown Molecular Analysis of the QacR Rhodamine 6G Binding Pocket  Bacterial multidrug resistance (MDR) is an ever growing health concern worldwide. In Staphylococcus aureus MDR can arise through efflux of the antimicrobial by the protein QacA. QacR, the transcriptional regulator of QacA, has the ability to bind many of the same substrates as QacA. This project aims to mutate residues lining the Rhodamine 6G binding pocket of the extended QacR ligand binding pocket, and observe effects on ligand binding in vitro, and DNA binding in vivo. A better understanding of these interactions can ultimately lead to the design of antimicrobials that do not trigger this mechanism of resistance.
	Zhou Yu Supervised by Bruce Lyon Evaluation of genome structure and diversity in the cotton pathogen Xem
Semester 2 2006
	Haley Bowcock Supervised by Rick Shine Males and females may have evolutionarily divergent interests when it comes to reproduction; this sexual conflict may manifest in coercion, manipulation, harassment and even harm of one sex by the other. I will investigate the potential role sexual conflict in the mating behaviour of anurans (frogs and toads), by focusing on the key mating posture of amplexus. I will use the Cane Toad, Bufo marinus, as a model system with which to investigate the mechanisms determining the duration of amplexus, and what the costs of this behaviour are to the female.
	Travis Child Supervised by Rick Shine, Ben Phillips, Jonno Webb and Greg Brown Untying the knot: aggregation and emigration in metamorph cane toads (Bufo marinus). Early observers of mass migration in toadlets noted its uncanny correlation with rainfall. This led to the belief that toadlets were spawned in clouds and literally fell to the earth with raindrops. Pursuing this idea was the likes of 'The Academy on the Raining of Toads' in Paris, 1859. In New York in 1869 it was pronounced 'a question for philosophers'. By 1940 in Chicago, ‘toad showers’ were declared a myth. In 2006, as a member of 'Team Bufo', the aim of my project is to rediscover and provide scientific insight into the important relationship between dispersal behaviour in toadlets and environmental variables.
	click here for more photos by Travis
	Ros Gloag Co-supervised by Madeleine Beekman and Ben Oldryod Inter-colonial interactions in an Australian stingless bee Trigona carbonaria. Domestication of stingless bees (Meliponiculture) for pollination services holds considerable promise for Australian tropical horticulture. However, aggressive inter-colonial interactions can be problematic in Meliparies, which impose artificially high nest densities. Successful domestication therefore depends in part on understanding intra-nidal conflict. ‘Fighting swarms’ in which large numbers of workers engage in air-borne battles are an example of such conflict. These conflicts possibly arise because of adaptive defence against robbing behaviour and inter-colonial reproductive parasitism. This project will determine the origins of aggressive interactions between nests in a species proposed for domestication Trigona carbonaria.
	Lindsay Gray Co-supervised by Steve Simpson, Greg Sword, and Fiona Clissold The Australian plague locust (Chortoicetes terminifera) is a serious agricultural pest costing millions of dollars in losses to agriculture and control every year. In favourable conditions, populations of Australian plague locusts can rapidly increase in size and density. Populations can subsequently migrate en masse from the semi-arid interior into agricultural areas. My study will investigate whether the Australian plague locust, like other migrating locust species, expresses density-dependent behavioural phase polyphenism, a process believed to be important in the initiation and dynamics of swarming and migratory behaviour.
	Crystal Kelehear Co-supervised by Rick Shine and Jonno Webb Host-parasite interactions between a lung nematode (Rhabdias cf. halae) and the introduced cane toad (Bufo marinus) Parasites have a significant influence on population viability but have traditionally been excluded from explanatory models of host population dynamics. This research aims to determine whether parasites influence host populations through effects on growth, locomotor performance and survival, using the cane toad (Bufo marinus) and the lung helminth (Rhabdias cf. hylae) as a model system. The potential for an interaction between response to infection and parasite exposure history will also be explored. The results of this study will provide novel insight into host-parasite interactions and their influence on host population dynamics.
	Alex Jordan Co-supervised by Ben Oldroyd and Madeleine Beekman Hybrids zones occur where genetically distinct groups of organisms come into contact and produce viable hybrid offspring. My study will examine a unique hybrid zone between the two African honey-bee subspecies, Apis mellifera scutellata and Apis mellifera capensis. The stability of this hybrid zone is unexpected as A. m. capensis is a lethal social parasite on A. m. scutellata, and A. m. scutellata is a successful invasive species in much of the Americas. Behavioural and genetic mechanisms that may contribute to the stability of this hybrid zone will be explored using ecological and genetic approaches.
	Helen Stephens Co-supervised by Clare McArthur and Charlotte Taylor Interactions between browsing Rusa deer (Cervus timorensis) and plants in Royal National Park This project investigates the foraging behaviour of the Rusa deer, an introduced mixed-feeder mammalian, and the responses of plants to this behaviour. Browsing preferences and the vulnerability of focal plants in relation to neighbouring vegetation will be explored. Reproductive, chemical and structural responses of plants to herbivory will be used to predict the impact Rusa deer have on plant species and assemblages in a key ecological community. This project has implications for the management of a key threatening species by providing information on deer behaviour and impacts.