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Thursday 13th December, 2007 at 7pm
Speaker: Professor Matthew England RSV (2007 Medalist)
Climate and Environmental Dynamics Laboratory, School of Mathematics & Statistics
The University of New South Wales
TOPIC: Water-Mass Variability And Change In The Southern Ocean
Detection of long-term climate change requires knowledge of natural variability in the ocean-atmosphere system. In the Southern Hemisphere, climate variability is evident on time-scales of days to centuries, yet we know relatively little about how this forces interior ocean fluctuations, nor how these fluctuations feedback to the atmosphere. In this talk the magnitude and mechanisms of Southern Ocean water-mass variability will be examined in models and (where available) observations. A review of our knowledge of Southern Ocean climate change will also be presented, including the latest projections for the next 50-100 years.
In terms of natural variability, substantial Southern Ocean heat content anomalies can be generated via fluctuations in winds, sea-ice and air-sea exchanges. For example, the Southern Annular Mode projects onto sea surface temperature (SST) in a coordinated annular manner - with a conspiring of dynamic and thermodynamic processes yielding a strong SST signal. We find that substantial water-mass changes can result from a gradual latitudinal shift in the zonal wind-stress maximum associated with the subpolar westerlies, as has occurred recently. The implications of these findings for climate change/variability are discussed.
Thursday 8th November, 2007 at 8pm
Speaker: Dr. Mary Familari Department of Zoology
The University of Melbourne
TOPIC: Stem Cells Made Easy
In 1998, the first isolation of human embryonic stem cells was reported by Thomson and colleagues which firmly placed the prospect of repairing damaged or injured tissues using cells manipulated in vitro into the 'possible and likely basket'. Stem cell transplantation therapies are no longer in the 'too hard basket' making the prospect of transferring healthy, for example, neural cells into patients suffering from Parkinson's and other neurodegenerative diseases or pancreatic beta cells into diabetics a very reasonable clinical expectation.
What are stem cells? All stem cells share the same basic characteristics, the ability to propagate indefinitely and the ability to become many different cell types; in stem cell parlance the properties are known as self-renewal and pluripotency respectively.
Stem cells are found in one of the earliest structures of a developing mammalian organism, the blastocyst, specifically the cells that will become the organism, the so called embryonic stem cells. In addition stem cells are found in bone marrow, placental umbilical cord blood and are presumed to exist in all somatic tissues and organs, based on the observation that all tissues in the juvenile and adult body can repair themselves after injury. The non-embryonic stem cells are traditionally called 'adult stem cells' but clearly the nomenclature is clumsy as placental tissue is not adult, and stem cells exist in children. Therefore the preferred grouping should be 'somatic stem cells' to distinguish them from embryonic stem cells and to position them in all tissues from neonate through to adult.
The pluripotency (or the ability to form one, several or many different cell types) however, varies amongst these types of stem cells. For example, bone marrow hematopoietic stem cells are able to give rise to all the cell types of the blood, whereas embryonic stem cells are capable of forming all the cell types in an organism and in fact that is what they do in an embryo.
Since the classic experiments of Jacobson et al., (1951) and Till and McCullock (1961), bone marrow transplantation leading to the ability to repopulate the blood cell lineages and the cure of several types of leukemia are now familiar and routine procedures, and Australia has led the way in this area of research. More recently the existence of another non-blood related stem cell, the so called mesenchymal stem cell has been identified in the bone marrow and its ability to give rise to blood cell types, muscle, neural and liver cell types has stimulated an enormous interest in these cells. There are several interesting reports in which blood (from male donors) transfusions into female recipients has led to the identification of male cardiac muscle cells suggesting that mesenchymal stem cells may circulate and repair tissues as needed. Although this is a hotly debated issue that is yet to be resolved, it may provide new paradigms for how stem cells repair damaged somatic tissues.
Many differences exist between embryonic and somatic stem cells. One important difference is their pluripotency. The latter are considered multipotent because so far, under current in vivo conditions, only a limited number of cell types are derived. Other differences are that human embryonic stem cells are found in large numbers, have been clearly identified and can propagate indefinitely in culture. In addition, human embryonic stem cells are derived from surplus frozen blastocysts that couples undergoing In vitro fertilisation techniques consent to donate for research. Therein lies the essence of the controversy generated by these embryonic cells - the blastocyst must be destroyed to derive these human cell lines. Objections by opponents of this research are firmly based in the notion that a human blastocyst has the potential for life and the sacredness of human life. Proponents defend their work by highlighting the surplus nature of the blastocysts and thus the inevitable destruction of these cells and the incredible potential for cell transplantation therapies.
The ability to generate custom-made, immuno-compatible cell types via therapeutic cloning legalised in Australia last year and in Victoria in April 2007 has certainly paved the way for the expansion of this technology. Large sums of research dollars are being invested both privately and by governments to promote cell transplantation therapies. Will this promise be realised in our lifetime? This is an interesting question but regardless of one's view, almost certainly our understanding of early human development previously inaccessible and how cells become specialised will be hugely advanced by the concerted efforts of researchers worldwide to replace damaged tissues in sufferer's of Parkinson’s disease, Diabetes, myocardial infarction, and the wish-list goes on....
Thursday 11th October, 2007 at 7pm
Speaker: Dr. Jeremy Austin Australian Centre for Ancient DNA, School of Earth and Environmental Sciences
The University of Adelaide
TOPIC: Dodos to DNA. What Can DNA Tell Us About The History and Ecology of Extinct Species
Ancient DNA – DNA recovered from post-mortem remains of animals, plants and humans – holds tremendous potential for the study of the origins and evolution of extinct species, ancient animal and plant populations, human origins and to record genetic changes in real time. However, ancient DNA research is limited by the small amounts of degraded and damaged DNA found in most ancient specimens and problems of contamination from external sources. This talk will discuss the scope and history of ancient DNA research and will provide a number of examples of recent and ongoing research projects that are helping to understand the history and ecology of extinct species, including the Dodo from Mauritius, moa from New Zealand and Tasmanian tiger.
DNA, deoxyribonucleic acid, has a number of characteristics that make it the molecule of choice to study evolution. DNA has a common structure and function in all living cells, allowing deep comparisons between diverse groups of organisms such as bacteria, animals and plants but also very shallow comparisons between closely related individuals. DNA carries the genetic code, the four-letter alphabet of life- A, C, G, T. Changes in the genetic code occur through mutation and these accumulate over time in a roughly clock-like manner providing a measure of how related or unrelated two individuals, populations or species are and the time since they last shared a common ancestor.
DNA-based evolutionary research utilises the hierarchical nature of evolution. At a broad scale DNA variation can be used to understand the origins of life and relationships between major groups of organisms. At a finer scale, DNA sequence variation provides information on the phylogenetic relationships between ever-more closely related groups – Orders, Families, Genera and Species. At a finer-scale still genetic variation can be used to understand how populations have changed over time, how individuals have moved between populations and whether species are made up of one or many sub-populations. At the finest scale, DNA can be used to test relationships between individuals and to identify individuals.
Ancient DNA research is firmly based within traditional molecular evolutionary research however it significantly extends the field by providing access to genetic information from the past – a real (not extrapolated) temporal view of evolution. The use of ancient DNA allows us to include extinct as well as extant species in evolutionary studies, identify a species' presence in the past without fossil evidence, identify unknown species and species-diversity with limited or cryptic fossil evidence, identify movement of populations in space and time and reveal demographic change in populations which can be related back to environmental change and human impacts.
Ancient DNA is DNA post-mortem and is characterised by being degraded, broken into increasingly shorter fragments, chemically modified and present at very low concentration. Ancient DNA can be found in a range of sources including forenic samples, pathology specimens, museum specimens, archaeological material, sub-fossil bones, natural mummified remains, scats, shed hair and skin and sediments. The rapid degradation of DNA post-mortem means that DNA survival is not indefinite. Despite a number of unsubstantiated claims of DNA surviving for millions of years, the oldest believable recovery of ancient DNA comes from material less than 100,000 years old. Cold, dry environments provide the greatest protection for DNA, thus the oldest ancient DNA records come from dry caves at high latitude or altitude and from permafrost in northern Asia and America.
Working with ancient DNA is not without substantial challenges. Poor DNA preservation in many (or most!) samples means that many specimens contain little of no DNA. High levels of DNA fragmentation, damage and chemical modification limit the amount of genetic information that can be obtained and can introduce significant levels of error into any DNA sequence recovered. Contamination from external sources can produce a false positive result. Contamination is one of the greatest concerns because contaminating DNA can originate from a multitude of sources and is invariably better preserved and at higher concentration than any DNA that survives in a specimen itself. Ancient DNA work therefore requires very careful field collection and a specialist ultra-low DNA laboratory in order to minimise the opportunities for contamination.
The Australian Centre for Ancient DNA at the University of Adelaide is an international-standard specialist low-DNA laboratory. The laboratory is one of only three such high-class facilities in the world and is the only one in the Southern Hemisphere. The laboratory incorporates specialised air-handling systems with positive, HEPA-filtered air pressure, overhead UV light sterilisation and requires staff to wear full body protection to prevent contamination of specimens by human and other external sources of DNA. The laboratory is compartmentalised with individual still-air working rooms and glove-boxes to allow researchers to work in isolation, further reducing opportunities for contamination.
Five case-studies demonstrating the utility of ancient DNA in evolutionary research are discussed. The dodo (Raphus cucullatus) and solitaire (Pezophaps solitaria) were two large flightless birds from the island of Mauritius and Rodrigues in the western Indian Ocean. Both species went extinct soon after the arrival of European settlers in the 16th Century and ever since there has been debate about their origins and phylogenetic affinities. DNA extracted from the only remaining museum specimen of a dodo and sub-fossil bones of the solitaire revealed that both species shared a common ancestor, that they are both part of the pigeon family and that their nearest living relatives inhabit islands in Asia and south-east Asia. The dodo and solitaire were descended from a pigeon that made an amazing oceanic dispersal from Asia and subsequently lost the power of flight.
Endemic giant land tortoises (Cylindraspis) from the Mascarene islands in the western Indian Ocean also went extinct after the arrival of Europeans. There were five island species which were unique in a number of ways. Their shells were thin and provided little protection from predators unlike continental species that rely on their shells as a safe-haven from predators. On two of the three Mascarene islands (Mauritius and Rodrigues) there were two species – one round shelled and one saddle-backed shelled suggesting differentiation based on feeding ecology. Ancient DNA extracted from sub-fossil bones from cave and swamp deposits from each island provided a robust phylogeny that showed that Mauritius was colonised first and the round shelled species was then the source of colonists to both Rodrigues and Reunion. Saddlebacked shells with high fronts evolved independently on all three islands – a striking example of parallel evolution of similar body plans on independent islands.
The extinct giant flightless birds of New Zealand, moa, have been the focus of several important ancient DNA studies. Moa taxonomy has a confused history with the number of described species varying significantly over the last 100 years. Ancient DNA has provided a means to clarify the taxonomy of at least one group of moa belonging to the genus Dinornis. Traditionally, three species were recognised based largely on body size – small, medium and large. Body size variation was significant, with height varying from 1-2m and estimated body weights from 34-242kg. All three species were thought to occur on both the north and south islands. The traditional taxonomy was turned on its head when two ancient DNA studies examined a range of bones from all three "species" from across New Zealand. DNA sequences revealed that there were only two species, one on the north island and one on the south island. A DNA-based sex identification test allowed the sex of each specimen examined to be established. Amazingly, all the larger specimens were females and all the smaller specimens were males, an unusual case of extreme sexual dimorphism.
Moa were key elements of the New Zealand pre-human ecosystem, being the only large terrestrial herbivores. Understanding moa diet is important to understand their role in shaping the New Zealand landscape. Moa diet can be assessed using two sources - gizzard contents found associated with moa skeletons in peat bogs or coprolites - semi-fossilised scats. Both sources provide information on what moa were eating, but only gizzard contents allow identification of the moa species. Coprolites cannot be attributed to a particular moa species based on size, shape or texture. However, traces of moa DNA in the coprolite can provide accurate species identification allowing diet of different moa species to be studied. Recent work at the Australian Centre for Ancient DNA has used ancient DNA to identify moa coprolites from one site in New Zealand, revealing substantial shifts in the size and composition of plants being consumed by the same species of moa from different habitats.
Tasmanian tigers, or thylacines, were Australia's largest carnivorous marsupial. The last known thylacine died in Hobart Zoo in 1936 and the species was officially declared extinct in 1986. Speculation continues about the survival of thylacines in Tasmania and thylacine sightings have been common-place during the last 100 years. To date no physical evidence for the survival of thylacines beyond 1936 has been produced. Large mammal scats collected from the Tasmanian bush during the last half of the 20th Century have been deposited in both the Tasmanian Museum and Art Gallery and the Queen Victoria Museum and Art Gallery. Positive identification of these scats has not been possible. Ongoing research at the Australian Centre for Ancient DNA is attempting to use DNA extracted from these scats to identify their species of origin. DNA testing will be able to distinguish cat, dog, thylacine, Tasmanian devil and two species of quoll, the only six species capable of producing large scats in Tasmania. Currently several scats have been identified as originating from Tasmanian devils, but the search for evidence of thylacines continues.
Thursday 13th September, 2007 at 7pm
Speaker: Dr W Jim Peacock AC FRS FAA FTSE
Chief Scientist
TOPIC: Science For Australia's Future
Role played by humans Not so long ago the major role that humans have been playing in increasing the pace and magnitude of climate change was the sole province of comment and attention by scientists. Thanks largely to the emerging scientific evidence, the debate surrounding the reality of climate change has moved from disbelief to acceptance. Scientists have been joined by economists, business people, governments – both national and internationally – and the general population.
Climate change presents us with environmental, social and economic challenges. Australia's future will rely on the readiness of all Australians to work together in tackling these challenges and also on international efforts.
According to the Intergovernmental Panel on Climate Change, "warming of the climate system is unequivocal" (IPCC 2007). Human activities are certainly increasing the greenhouse gas emissions that lead to climate change.
The current drought is expected to reduce GDP by 0.75 per cent. The reality is that with climate change the amount of drought affected land in Australia will increase in the future. We need to adapt to our changing climate and accept our new reality. This is a major challenge – the major challenge? There are three factors that we need to keep in mind:
• First, the time dimension that we face
• Second, the patchwork and complexity of the needed actions and
• Third, the necessity of partnerships.
Timing Since 1910 Australian mean annual temperatures have increased by around one degree Celsius. The majority of this increase has occurred since the 1950s. The best estimate we have is that average surface temperatures will rise by 1.8 to 3.5 degrees Celsius by the end of the century. Under a more challenging scenario, inland temperatures will rise even more – by about 5 degrees Celsius. If this occurs, living on parts of our globe will be difficult for humans and for the survival of many ecosystems.
We must reduce the steep rise of emissions and find ways to "buy time". Mitigation measures reducing emissions and the introduction of new, low carbon energy generation systems take time. These are not overnight happenings and theyinvolve large investments.
We also need to prepare right now for the impact of the emission driven climate consequences that are with us – this while we set about reducing the emissions footprint.
It will not be easy to achieve any significant levels in the reduction of emissions within the next 15 years. Even if we initiate various actions right now, the complexities involved in establishing the portfolio of initiatives and the difficulties organising concerted efforts by many countries, emphasise the time lag and the need for partnerships between business, governments and research institutions.
One of the most encouraging signals during 2007 was the release of the climate change adaptation framework that has been endorsed by the Council of Australian Governments.
The Patchwork Not everything is doom and gloom. Responding to climate change is like making an heirloom quilt. It will take time but we need to accept the challenge, seize the initiative and fit the pieces of the patchwork together. The sum of the whole will help protect Australia from increasing extreme weather events and the enhanced greenhouse effect. There are a number of "pieces" or actions, that I would like to mention:
Biosequestration What is the potential to store carbon dioxide in living plants, particularly trees and woody shrubs and even grasses? What is the capacity in Australia? We have to consider additional storage over and above what we are currently sequestering in vegetation – the delta.
This is a very complex situation. We need to take into account land use, rainfall and runoff characteristics of the different regions of the country, the prospects of fire and whether management against fire should utilise controlled, frequent fire regimes, or whether we allow a major build up of carbon dioxide storage vegetation and risk the chance of major fires. But there is a real prospect of large scale additional storage in trees and shrubs in Australia.
Our greenhouse gas emissions currently amount to about 550 Mt of CO2 equivalents a year. If we could use 5 per cent of the potential new forest and savannah areas (with rainfall exceeding 300mm a year) then we would store 20 mtpa – almost 10 per cent of current electricity generation emissions, which account for 35 per cent of Australia's total current emissions. If we also work hard at improving the efficiency of energy usage we could be accounting for at least 20 per cent savings. We should be able to access more that 5 per cent of the available land area.
We are a relatively sophisticated technological nation People ask why should we bother cleaning up our act when we are only responsible for about 1 per cent of global emissions? Because it is worthwhile and we need to play our part as a global citizen. We should be able to help some of the major emitters in the globe to significantly reduce their contribution to global greenhouse gas emissions. All countries need to be part of the global solution.
Greenhouse gas emissions in Australia We have the potential to substantially reduce the emissions from stationary energy. We would like to be able to do it without extra costs to the consumers for electricity, but that is not possible, certainly not at present. It is highly likely that Australian consumers will not continue to enjoy the cheap electricity prices that we have today. We need to develop a portfolio of energy sources for electricity production.
Clean coal and nuclear will take 10 to 15 years Currently there are only two sources that are technologically mature and capable of providing us with base load electricity with reduced emissions. These are to clean up the coal based technologies – to introduce both pre- and post-combustion carbon capture – and geosequestration of that carbon dioxide. The second source is nuclear energy.
Solar thermal a real possibility in the near future – even now Solar thermal can be constructed and become operational in a short timeframe, a matter of months, and can be in a distributed mode supplying daylight power for small towns, or dedicated to particular manufacturing systems throughout the country. They can be connected to the grid and can both supplant and add to grid supplied electricity.
Photovoltaic is highly developed in Australia We have some world leading technologies but it is still relatively costly. We need to invest heavily in further research with subsequent demonstrations towards commercial applications in order for it to become a reality. Photovoltaic technology will continue to gain efficiency and cost reductions over the next 10 to 20 years.
Geothermal is potentially a hugely available source of power in Australia Another low carbon source of energy that we have plenty of in Australia is geothermal energy. In this case water is introduced among hot rocks 4 to 5 kilometres underground and recovered to produce steam and subsequently electricity. There are no gas emissions produced. One problem is that most of the suitable geothermal reservoirs are in areas that are a long way away from our population centers – the tyranny of our geography and geology.
Research is still required to diversify Australia’s energy supplies to ensure emissions are substantially reduced and hopefully at an acceptable price to customers.
Conclusion Partnerships & Patchwork What else can we do to reduce our emissions? Is there anything we can do in the next 10 to 15 years? We need to ask ourselves these questions every day. There is substantial potential for us to reduce our emissions by reducing our energy usage, even though with population increase and other factors we have been steadily increasing our energy demand.
The Australian scientific community has a significant opportunity to collaborate, form partnerships, agreements and new alliances with other scientists, government and industry – both in Australia and overseas.
We have real opportunities in this country to maintain our quality of life and help other countries – including large emitting countries– do the same. We need to look at every aspect of our greenhouse signature and do everything we can to reduce its impact, not only for our generation but for the generations to come. They will depend on the patchwork quilt we stitch together to cope with the climate change challenge.
Thursday 9th August, 2007 at 7pm
Speaker: Professor Tom McMahon Department of Civil Engineering
The University of Melbourne
TOPIC: Variability of Stream Flows
The talk dealt with a number of issues relating to the variability of streamflow. I began by describing how streamflow is measured at a specific point along a stream noting the potential difficulties in this exercise. Next, I defined streamflow variability and presented four types of streamflow that typify Australian variability. The body of the talk concentrated on the higher values of variability observed for Australian (and southern African) rivers compared with those observed in the rest of the world and reasons for this feature. In the final part of the talk I will discuss several aspects of the present drought.
A basic data set necessary for any surface water investigation is a time series of historical daily flows which are then cumulated to give a monthly and an annual record. The data are obtained at a stream gauging station where there is a continuous recording of water level which is converted to discharge through a rating curve, the latter being established by measurement. Major data errors can occur if the rating curve needs to be extrapolated.
Variability in streamflow can be considered from many points of view. In this talk I adopted the coefficient of variation (Cv) of annual streamflows defined as the standard deviation of annual flows divided by the mean annual flow. This measure is used widely in hydrology. The four rivers that illustrate the various types of river flow are perennial streams (e.g. Thomson River, Vic with Cv = 0.3), perennial streams but with cease-to-flow conditions occurring rarely (Queanbeyan River, NSW with Cv = 1.1), ephemeral streams with annual cease-to-flows (Ord River, WA with Cv = 0.7) and ephemeral streams with no regular seasonal flow (Todd River, NT with Cv = 1.5). For comparison, the annual Cv of Melbourne’s rainfall is 0.2.
A central part of the talk illustrated that the variability of Australian rivers exhibit annual Cvs that are about double that found globally. This observation applies to rivers located in temperate, tropical and arid climates and is independent of catchment area. In the talk, reasons for this characteristic will be discussed including vegetation characteristics (evergreen vs deciduous landscapes) and rainfall variability. Because of these effects, for equivalent conditions water available for regulation from large reservoirs in Australia is about 30% less than that available in Europe. In the talk, other activities that affect streamflow variability were described including land cover change on small and large catchments (changing from native forest to grassland in the Comet catchment in Queensland resulted in runoff increasing by 35% and annual Cv increasing by about 13%), irrigations withdrawals from unregulated streams, inter-basin transfers and local scale effects.
In the talk I explored the length and severity of drought as represented by both low rainfalls and low streamflows, and concluded that the length of drought in Australia is no longer than those observed globally. However, I noted that the deficit of low streamflows is more severe in Australia compared with the severity of streamflow drought in the northern hemisphere.
I concluded the talk with an estimate of the average recurrence interval of the last 10 years of low rainfalls in Melbourne being about 930 years.
Thursday 12th July, 2007 at 7pm
Speaker: Professor Richard Rousch Land and Food Resources
The University of Melbourne
TOPIC: Transgenic Crops: Bane for the Environment or part of Sustainable Agriculture
Key issues for the sustainability of agriculture include conservation of soil, water and energy, and reduction of the use of fertilizers and so-called "bad actor" pesticides. Reduction of fossil fuel use, tillage and nitrogen fertilizers are especially important for reducing greenhouse gasses. We also need to ensure that farmers remain financially viable.
Genetically modified crops already commercialized or in field trials have helped to address all of these needs. GM cops have reduced the use of insecticides by 80% on cotton in China and India, reduced tillage has in turn reduced CO2 emissions by the equivalent of removing some 4 millions cars from the roads, and increased farmer profits. Drought tolerant and nitrogen-use-efficient crops have been field-trialled and at least some show good yields. Salt tolerant crops have been tested at least in the lab. There has also been extensive testing of GM for safety to non-target organisms and for food and feed. Strategies to slow or prevent the evolution of resistance in insect, pests and weeds in GM corps have been developed and some implemented. Overall, GM crops are already playing a key role in sustainable agriculture and have a promising future.
Thursday 14th June, 2007 at 7pm
Speaker: Dr. Barrie McKelvey Division of Earth Sciences
School of Environmental Sciences and Natural Resources Management
University of New England
TOPIC: The Antarctic Ice Sheet - A Controversial History
Antarctica with an area of 13,500 000 square kilometres, almost twice that of Australia, is mantled by a vast sheet of ice that covers more than 98% of the landmass. This sheet in places exceeds 4.7 km in thickness and has depressed parts of the continent to below sea level. The South Pole located at 2800 metres above sea level is underlain by nearly 2700 metres of ice. Antarctica's ice constitutes about 70% of Earth's freshwater and 90% of its ice. Two major domains of this ice cover are recognised, the West Antarctic Ice Sheet and the much larger East Antarctic Ice Sheet. Both are composed of large coalesced and yet independent drainage basins.
With our planet now embarked upon a period of global warming much consideration is being given as to how the overall ice sheet will respond. Will it shrink and largely disappear causing a calamitous global rise in sea level? Alternatively will the vast sheet of ice remain relatively unaltered, insulated by its own self generated climate? Should the whole ice sheet disappear global sea level would rise about 65 metres. To this end much geological research is being directed towards deciphering how ancestral phases of the ice sheet have responded to climate change in the past. This work has largely involved establishing the distribution and ages of glacial deposits left by ancestral phases of the ice sheet. Such data is hard won and until recently mostly recovered from the few mountainous ice free oases occurring in East Antarctica (e.g. Amery Oasis, Bunger and Vestfold Hills) and the Transantarctic Mountains (e.g. McMurdo Oasis, Meyer Desert.) Currently excellent data is being deciphered from marine drill core retrieved (at considerable expense) from Antarctica's continental shelf. These international programs such as those carried out by the pioneering ship based Deep Sea Drilling Project Leg 28 (Hayes & Frakes 1973) and the more recent Ocean Drilling Project Legs 113 (Barker & Kennet 1988), 119 (Barron & Larsen 1991), and 188 (O'Brien & Cooper 2001), along with the recently completed sea-ice based Cape Roberts Project (Barrett 2001) have delivered a wealth of glacial history detail.
It is now well established that Antarctica's original ice sheet (or sheets) first reached the continent's coast about 35 million years ago in the Oligocene Epoch. (The northern polar ice sheets only became established about 3 million years ago, and so Earth's current bipolar distribution of ice is a somewhat recent development.) For how much time prior to 35 million years ago did ice occupy Antarctica is a matter of conjecture. Since 35 million years ago the continental ice cover is known to have waxed and waned across the continent as Antarctica continued to cool via irregular glacial - interglacial cycles largely controlled by geometric variations of Earth's orbit around the Sun. About 14 million years ago the cooling Antarctica abruptly plunged into yet deeper refrigeration, a state from which it only emerged about 20 thousand years ago. Controversy abounds as to the continents climatic stability over these last 14 million years. Some workers (the dynamicists) contend that during this last phase of deep refrigeration there occurred major collapses of the ice sheet, whereas other workers (the stabilists) hold that the ice sheets regime was more one of unchanging permanence. This controversy is fuelled by the knowledge that at least one period of world wide global warming occurred in the Pliocene Epoch about 3 million years ago.
To date the best onshore record of deposits left by ancestral phases of the ice sheet have been located in the Prince Charles Mountains of East Antarctica. These mountains flank the 550 km long Lambert Glacier - Amery Ice Shelf drainage system, the largest known in Antarctica and one which delivers some 35 cubic kilometres of ice into the Southern Ocean each year. On the slopes and crests of the Prince Charles Mountains stratified sequences of glacial debris known as the Pagodroma Group (Hambrey & McKelvey 2000; McKelvey et al 2001) mantle relict fragments of the floors and walls of ancient fjords some of which have been lifted by crustal movements to nearly 1500 metres above sea level. These "fossil" fjords were cut by expanding phases of the ice sheet and their mantles of glacial debris subsequently deposited in close proximity to the terminal ice cliffs of recessional phases of ancestral Lambert Glaciers. Throughout the Prince Charles Mountains the nature and distribution of the glacial deposits indicate these ice termini fluctuated (during advances and recessions) over distances of up to 500 kilometres. Minute microfossils (marine diatoms) allow at least three recessions to be dated at ca. 2.6 - 1.8 million years, between ca.12 - 9 million years and perhaps at ca. 30 million years (Whitehead et al 2004).
As the Lambert Glacier - Amery Ice Shelf drainage system presently accounts for more than 15% of the grounded East Antarctic Ice Sheet then the glacial history interpreted from these deposits is very possibly representative of the East Antarctic Ice Sheet as a whole. However much more geological field exploration in East Antarctica is needed to confirm this. More pertinent to Earth's present inhabitants is research into the Antarctic Ice Sheet's current behaviour as the planet's climate, since exiting from the last glacial maximum at 20,000 years ago, continues to warm. Data are few and often conflicting. There is strong evidence that the West Antarctic Ice sheet has thinned by as much as 750 metres in the last 10,000 years (Stone et al. 2003. However, in
contrast the overall volume of the Lambert Glacier – Amery Ice Shelf drainage system may be increasing, for more ice appears to be entering the head of the system than is calving into the Southern Ocean.
Currently there is little melting of the Antarctic Ice Sheet and its contribution to sea level rise by this mechanism is negligible. Rather any diminution of its volume is caused by increased calving at receding glacier fronts and ice shelf margins grounded in fjords and on the continental shelf. Only slight increases in sea water temperature and sea level will promote the calving, which in turn promotes the coastwards outflow of continental ice. Another factor to be contemplated is that the growth or decay of the much more sensitive northern hemisphere ice sheets may, by so controlling global sea level, thus control the size and volume of the Antarctic Ice Sheet.
Thursday 10th May, 2007 at 8pm
Speaker: Assoc. Prof. H. Miles Prince Chair of Cancer Services
Peter MacCallum Cancer Institute
Topic: Harnessing the Immune System to Tackle Cancer
Cancer growth is a balance between the speed at which cancer cells divide, the capacity of those cells to continue to undergo "programmed cell death" otherwise known as apoptosis, the viability of the tumour microenvironment to support the tumour growth and importantly, the immune system's response to the tumour.
Over the last few years we have gained greater insight into the role of the immune system in controlling cancer cell growth. Normal cells within the body can be "insulted" by various external processes such as chronic inflammation, viruses, radiation and other carcinogens, such as cigarette smoke or ultraviolet light. Moreover, these cells may be inherently prone to mutations because of various inherited genetic weaknesses in cells. Cells, once damaged, may then die or they may attempt to repair.
If that repair mechanism is unsuccessful the cells may undergo a process of transformation where the cells alter the cell surface expression of various proteins. These proteins are abnormal and not usually expressed on such cells and although the cells may maintain some of the inherent characteristics of their "normal" counterpart, their cellular coat (or 'uniform') changes, which makes the cell appear foreign to the body's immune system. A process called cancer immunoediting is a concept recently recognized, whereby the immune system attempts to eliminate these transformed cells. This elimination is through non-specific and specific recognition mechanisms. There are a variety of cells involved in that process, particularly T-cells and variations thereof, including cytotoxic T-cells, helper T-cells, gama-delta T-cells and natural killer cells. These cells attempt to recognise the transformed cell and kill it through the direct cytotoxic effects or through interactions with other components of the immune system, such as B-cells.
If entirely successful, the transformed cells will be killed. However, a state of equilibrium can also result whereby the transformed cells remain and the T-cells wage an ongoing battle to suppress this abnormal clone. This places selection pressure on the tumour cells and there is potential for new sub-clones to develop.
Ultimately, cancer escape can result following a 'counter-attack' from the cancer cells against the defending immune system. Indeed, the cancer cells can produce immune-suppressing molecules and produce T regulatory cells which defeat the immune system, resulting in uncontrolled tumour growth. One of the big challenges we have in our fight to 'immune-modulate' cancer is to defeat this counter-attack that tumour's initiate.
Armed with this knowledge of immune surveillance we can try and utilise ways to use the immune system to find new therapies for cancer treatment. Indeed, there is a new group of drugs being developed which can directly stimulate immune cells such as T-cells, to fight cancers. Such examples include thalidomide and its derivatives, such as lenalidamide and other drugs such as the histone deacetylase inhibitors. A number of these drugs are already in trial for treatment of diseases such as myeloma, lymphoma and leukaemia.
The immune system can also be enhanced by modulating 'professional antigen presenting cells' such as dendritic cells. These dendritic cells can be produced in special laboratories and loaded with tumour antigens. This loading allows better recognition of the T-cells to kill the tumour. Like many centres around the world, Peter Mac has been involved in a number of dendritic cell studies in melanoma, myeloma, and various solid tumours.
Another way is by adoptive immunotherapy, where the T-cells can be removed from the body, enhanced, and subsequently re-infused back into patients. Such work is being performed at the National Institute of Health in the US led by Rosenberg and colleagues. They have demonstrated tumour responses which are strongly dependent on the persistence of the modified T-cells in the circulation. This adoptive immunotherapy approach is being progressively enhanced and there are a number of trials now which try and better target these tumours by gene modifying the T-cells to be better able to recognise the tumour and subsequently kill it. A number of these studies are underway around the world. Trials with T-cells directed against tumour cells expressing the Lewis-Y antigen are commencing in Victoria in the near future.
Such immune therapies are not simple to execute. We are fortunate to have a cell manipulation facility at Peter MacCallum where such cells can be grown safely for long periods of time with minimal risk of cell infection or contamination. Indeed a wide variety of trials have been done over the last few years. However, to undertake such trials requires a large number of focussed people. These include laboratory researchers, translational research scientists, clinicians and often the involvement of biotech or pharmaceutical companies to assist with the development of such strategies.
Our understanding of the immune system's capacity to control cancers is an exciting and rapidly evolving field. Harnessing this understanding and focusing the immune system towards killing cancer cells will no doubt be a growing component of our cancer-fighting armamentarium in the near future.
Thursday 12th April, 2007 at 8pm
Speaker: Assoc. Prof. Simon Watkins
Automotive Engineering, Mechanical & Manufacturing Engineering, RMIT University
Topic: AERODYNAMIC AND AEROACOUSTIC RESEARCH IN AUSTRALIA: BIG CARS AND SMALL PLANES
Coming soon.
Thursday 8th March, 2007 at 7pm
Speaker: Assoc. Professor Bruce G. Livett
Immediate Past-President Department of Biochemistry and Molecular Biology, The University of Melbourne
Topic: MOLECULAR PROSPECTING FOR A MOLLUSC’S MORPHINE: THE ONUS IS ON CONUS
It is said "there are only two kinds, the quick and the dead". In the 500 million years since the death of the dinosaurs, one class of animals that has adapted particularly well to its hostile environment is the slow moving carnivorous marine snail Conus, better known to beachcombers as the cone shell. This pretty mollusc hunts down its prey by use of a harpoon, or radula, which it attaches to the end of its long tongue (proboscis) and impales its victim immobilizing it with a toxic venom. Tourists on the Great Barrier Reef are warned not to pick up live cone shells as there is no antidote known. Some 30 human deaths from cone shell envenomation have been recorded. Death occurs because a toxic component in the venom cocktail blocks a communication channel (an ion channel) that is essential for the diaphragm muscle to contract and stops the victim from breathing.
Fortunately, there are other non-toxic components in the Conus venom cocktail, comprising up to 200 peptides, that are proving medically useful for treating neurological disorders, including chronic neuropathic pain. Neuropathic (nerve) pain affects one to three percent of the population. Common causes include diabetes, viral infection (e.g. shingles), sciatica, trauma and chemotherapy. In many cases the pain is severe, long lasting and debilitating. Neuropathic pain typically responds poorly to conventional analgesics such as morphine or aspirin, and current drugs provide relief to less than half of the affected individuals.
In this talk, our outgoing President, Dr. Bruce Livett will introduce us to the biology of these wonderful marine creatures and the therapeutic potential of a number of their specific venom components. He will describe how, by use of sensitive molecular biochemical techniques, it has been possible to mine this marine pharmaceutical cornucopia but with negligible impact on this species and its fragile reef environment. He will provide an account of the drug discovery process drawing upon the collaborative efforts of his team in biochemistry, pharmacology and physiology leading from the discovery of an active peptide component in the venom of Conus victoriae, from Broome, to the development by Metabolic Pharmaceuticals, Melbourne, of a novel analgesic (ACV1) with potential for treatment of range of painful conditions.
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