PhD and Honours by Research programs are available in most areas of my research. Some proposed topics are listed below. Other projects are also possible. Please contact Dr O'Brien to discuss areas of mutual interest.
Left and right cortex work closely together but often have specialize roles within a task. Nerve pathways controlling the limbs are generally well-known; this allows us to deduce which side of the brain is being used during an animal's normal activity, by monitoring which side of the body, e.g. left hand or right hand, is predominantly used for that activity.
This project may be undertaken in collaboration with Professor Lesley Rogers, Centre for Neuroscience and Animal Behaviour, UNE.
The aim of the present project is to carry out preliminary screening of antibodies to LH, to find one suitable for assay of LH in flying foxes.
Experimental Approach and Methods Test competitive binding of pituitary homogenates from flying foxes in radioimmunoassays (RIAs), using polyclonal and monoclonal antibodies against LH. Available antibodies will be compared using a heterologous double-antibody assay, with iodinated ovine LH (o-LH) as tracer, o-LH as reference preparation, and heterologous immunoglobulin separation of triplicate pituitary samples. Standard computer programs (e.g. Excel) will be used to analyse gamma-counts from each assay; then assays will be compared using ANOVA to select the antibody with most sensitive cross-reaction with Pteropus LH, and the optimum assay protocol.
Chemicals such as nitric oxide, serotonin, dopamine, and the opioids, have been implicated in the neurophysiology of euphoria. Limbic association cortex links autonomic functions, with affective or emotional states. Reproductive physiology has overlooked the roles of association cortex, and its possible involvement in fertility dysfunction, community health, and quality of life issues. This project aims:
This will be dissected into functions concerned with pathology (pre-epilepsy aura), pharmacology (hallucinogenic drugs), reproductive physiology (orgasm) and altered states of consciousness (meditation).
Association cortex is a higher processing region of brain, concerned with integrating information from other parts of the brain. Limbic association areas link autonomic functions, with affective or emotional states. Reproductive physiology has overlooked the roles of association cortex, and its possible involvement in fertility dysfunction, community health, and quality of life issues. This project aims:
This will be dissected into functions concerned with pathology (pre-epilepsy aura), pharmacology (hallucinogenic drugs), reproductive physiology (orgasm) and altered states of consciousness (meditation). Reproductive euphoria is usually induced by sensory stimulation of the external reproductive tract, and in many species the reproductive tract histology changes when fertility changes. In turn, the timecourse of fertility usually determines the timing of stimulation of the reproductive tract (i.e. mating).
Analyse prior reproductive history and current environmental factors, and their effects on human fertility, fecundity, and reproductive health.
The pituitary gland controls much of the endocrinology of the rest of the body. Therefore, if an animal responds to its environment, a response at the pituitary gland would precede a change in the "downstream" endocrine gland e.g. ovary or testis. Immunocytochemistry (ICC) uses antibodies raised against specific hormones, to find those hormones in cells in slices (sections) of the pituitary. These can be quantified:
Knowing the times at which regulatory mechanisms are activated (eg secretion of LH, FSH or prolactin) should allow us to deduce which environmental signals the animals are using to cue their breeding season.
Methods include sectioning paraffin blocks, reacting with antibodies, staining, collecting data with image analysis, analysing data and interpreting physiology of male and female flying foxes.
One way to find out what stage of reproduction an individual is in, is to collect small blood samples each day or week; then use radioimmunoassays (RIAs) to measure changes in gonadal steroid hormones.
An alternative to RIAs is bioassays: in this we measure something else that changes under the influence of the steroid hormones. We use these changes as an indirect measurement of the steroid hormones.
In humans, the uterine epithelium (endometrium) changes under the influence of ovarian hormones, oestrogen and progesterone, but the vaginal epithelium does not. In many non-human mammals, the epithelium of the vagina does change under these influences, and so can be used to estimate stages of ovarian cycles.
I have developed a vaginal cytology bioassay for an unusual species of flying fox, Pteropus scapulatus (the little red flying fox). For verification this needs to be:
The outcome would be a non-invasive technique for monitoring fertility, and predicting ovulation in these and closely related endangered species.
While studying the effects of photoperiod on the regulation of seasonal reproduction of flying foxes, I inadvertently unmasked a tendency for males to die during or after the breeding season: I have informally dubbed it "the antechinus effect".
Bronwyn McAllan, Julie Roberts and Tim O'Shea have examined the kidney changes that occur in male antechinus at the time of seasonal die-off. Postmortem examination of the flying foxes that succumbed to the 'Seasonal Mortality' syndrome showed vacuolation of kidneys and adrenal glands, and possibly enlarged adrenal glands. This needs to be pursued:
Investigation of Seasonal Mortality syndrome in flying foxes exposed our limited knowledge of the parasite Hepatocystis pteropi, and our complete lack of knowledge of its lifecycle. Apparently, H. pteropi exists in many animals as a non-pathogenic parasite, and is managed in a delicate balance with the animal's immune system. If the immune system is damaged the parasite may escape immune surveillance, and kill the host individual - in part by digesting its erythrocytes.
In collaboration with Dr Peter O'Donoghue, Associate Professor in the School of Molecular & Microbial Sciences at the University of Queensland, it will be necessary:
There is evidence that the function of Leydig cells is modulated by factors secreted by testicular cells. There are several projects available that involve production of Leydig cells in tissue culture:
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