Continental Shift

JULIAN CRIBB

Image: Enjoylife2/iStockphoto By the end of this century four fifths of Australia will have landscapes and wildlife that appear rather different to those we have grown up to think of as ‘Australian’.  Species will have moved: new ones appeared, familiar ones declined, new ecosystems will be forming. The kind of scenery immortalised by Hans Heysen and Tom Roberts may in many places have yielded to something new - in some cases unrecognisable - to today’s Australian eyes. The arrival of Aboriginal people and European settlers both wrought vast transformations on the face of our continent and the mix of species it contains - but today’s science now suggests these transformations may prove small compared with the overwhelming effects of climate change on every forest, grassland or desert, mountain, lake, river and wetland, beach, dune, estuary or reef and the plants and animals that inhabit them. In CSIRO’s Climate Adaptation Flagship a team of scientists is seeking to bring us a clearer picture of how profound those changes may be, how they will affect our perception of Australia and hence our own identity as Australians. Accepting that things are changing with a gathering pace in inexorable ways, they are examining the different sorts of species mixes, ecosystems and landscapes that are possible in the future so as to advise on which adaptation options are likely to be achievable, the amount of Australia’s unique life that is retained by enacting them, how and when to make critical decisions, how much those decisions will cost and how adjustable actions that play-out over long periods could be.  The changes in the earth system now being observed by scientists around the world are driven by carbon dioxide and other emissions whose rates now track the ‘worst case’ scenario envisaged by the Intergovernmental Panel on Climate Change (IPCC). If these emissions persist on their present track, by 2100 they will deliver 3-6 degrees Celsius average rise in global temperatures, an unprecedented level of ocean acidification, a 0.5-1.1 metre rise in sea levels (on its way to higher levels over the following century) and more extreme weather events – floods, fires, cyclones, heatwaves and droughts. This will affect all life in Australia dramatically and with a rapidity not seen for many millions of years. Understanding what this means, both for Australia’s unique biota and for ourselves, and what we can do as its stewards, goes to the heart of who we are and where we live. It challenges many of our cherished self-beliefs about our love of country, how we understand and care for it, our ability to shield it against harm and preserve its essential qualities. “The scale of the changes we expect climate change to impose will cause us to question the fundamental basis of how we now conserve Australia’s biodiversity,” says Dr Craig James, who leads the Managing Species and Natural Ecosystems Theme of the Climate Adaptation Flagship. “The challenge is to preserve the unique character of Australian biota. This is a challenge more complex than many of those faced by human-mediated systems because the number of effective actions we can make are fewer. Under the radically new conditions some species will thrive, some will tough it out – and some, regrettably, will go under. We will have to learn how to manage them all for the best, in increasingly dynamic circumstances.” Results from the models which the CSIRO researchers are developing to interpret the scale of environmental change have the power to shock. By the end of the century, environmental changes will most likely drive transformation of the mix of species – in some cases radically – on more than 80 per cent of the continent. Factors such as habitat loss and land clearing, erosion, water extraction, urban development and pollution all intersect with, and often exacerbate, the effects of climate change. The models and expert knowledge suggest that, in the most heavily-affected areas, life is ‘thinned out’ as species move, diminish in abundance or disappear. The most adaptable and hardy survive in their current locations. From the iconic eucalypts of Sydney and the Blue Mountains to the spinifex grasslands of central Australia, to the wetlands of Kakadu, to the vineyards of the south, the Australian landscapes we know and love will yield to new and unfamiliar scenes. Knowing how to cope with change on such a scale, and over so relatively short a time scale is an environmental challenge like none our scientists, policymakers or conservationists have confronted before.  It calls for a rethink of how we value and protect the quintessential character of Australia’s natural environments and its unique life forms. It calls for fresh national look at the value of natural areas to our wellbeing, and new stewardship concepts, goals and strategies. It demands we make every effort to mitigate the extremes of climate change by curbing our emissions. However, even the most extensive mitigation measures will not prevent many of these changes from taking place in Australian biodiversity – they are already locked in by past emissions. We therefore need to find ways to enable the biota to respond and adapt to the changing conditions.  Says biodiversity analyst Dr Michael Dunlop: “Almost everywhere, changes will affect the abundance and distribution of species, creating new assemblages and communities. This will alter the very structure of ecosystems and how they function. There could well be huge losses - some think this may involve up to 30 per cent of the local species, moving, declining or disappearing. We can reduce this loss by managing wisely and flexibly, but cannot prevent the changes altogether.” What this means, says the CSIRO researchers, is that Australia’s existing “static” approach to conservation – trying to protect and manage particular species in particular places – will no longer apply in  the dynamic and fast-evolving environments of the future. Our stewardship needs to adapt – just as the plants, animals and humans are themselves already adapting to the new conditions. Among the many changes, few are likely to affect urban and coastal Australia so much as sea level rise, exacerbated by an increase in storm surges and coastal erosion. A rise of 0.8m by 2100 sounds modest, but in many places it will drive wetlands, mangroves, coastal dunes and beaches hard against the inflexible barrier of human infrastructure. Unless they can find new high ground to occupy, the extent of these important coastal habitats will decline. Mangroves and dunes, especially, often shield coastal communities from the elements and their loss will expose them to the blows of a more turbulent climate. Trying to retain them may, in some cases, mean abandoning seaside areas and allowing nature to take its course: the effect on coastal people and their homes gives a sense of the stress that all natural ecosystems will face. Conversely, in flat, uninhabited parts of the continent, mangroves and salt marshes may flourish – sometimes at the expense of icons like the near-coastal freshwater wetlands of Kakadu. Scientific predictions for the Great Barrier Reef and Kakadu are well known, but other iconic Australian ecosystems face transformations as great or even greater, say the scientists. The continent’s Alpine and montane forests and heathlands may disappear, due to heat, loss of snowfall, drought and incursions of other species – and with them entire suites of cold-adapted marsupials, birds, reptiles, plants and frogs. For these, it will be immensely hard to find new, cool, wet havens.  Desert and rangeland ecosystems are likely to expand and even prosper, the scientists consider, gnawing into the outer fringes of Australia’s grain belt and temperate woodlands. Climate change may bring more rain to certain environments (such as the north-western deserts) – but it also brings  higher rates of evaporation, and the net result may be increased aridity, unfavourable to some species and favouring those most adapted to long, dry spells. Our “Mediterranean” climate zone, our current foodbowl and home of the southern woodlands with their spectacular abundance of native plants, animals and birds, will drift implacably towards the finite southern boundary of the continent, warns ecologist Dr David Hilbert. Whether these ecosystems can adapt or be rescued before they finally run out of suitable land is not yet clear. An analogy in the human world is that regions ideally suited for grape-growing will also gradually shift southward, first into Tasmania and then, eventually, to the far south of New Zealand.   Many Australian ecosystems are shaped by recurrent fire and thrive on it. “Fire regimes the patterns of recurrence of fire across the landscape are highly dependent on climate – the behaviour of individual fires is highly dependent on weather” says Darwin-based fire ecologist Dr Dick Williams. “We can expect fire regimes to change as a consequence of climate change.” By the end of the century there will be seasons of blazing heat and the incidence of fire risk levels well “off the scale” of today’s familiar bushfire warning signs will increase: such trends are already emerging. Only the most fire-adapted plants and animals are likely to withstand such extremes – and that applies also to the human communities which choose to make their home in fire-prone bush. Many individual Australian species are likely to cope with more intense fire because they have well-developed mechanisms of regeneration, honed over millions of years of evolution. But some native species are sensitive to the intervals between fires, and others are sensitive to the intensity; so more frequent and more intense fires as a consequence of climate change may be a threat to them. The overall result is that landscapes, species mix and ecosystems are liable to change significantly. Some introduced weeds, not being as fire-adapted as the locals, may suffer a setback, but others, such as gamba grass in the north, buffel grass in the centre and veldt grass in the south respond to fire better than the native species and will drive ecosystem change because they promote fiercer, more frequent fires. Drought too has shaped our landscape and crafted our unique plants and animals: its effects will amplify as the century advances. Drought may indeed favour the most dry-adapted of Australian species – but equally it could favour the hardy alien grasses and shrubs with which many Australians have, without thought to the consequences, imported to sow in pastures, for soil stabilization or water-saving gardens. These invaders have potential to reshape Australian landscapes and their mix of native species in ways just as devastating as the rabbit, the fox, blackberries or buffel grass, says weed ecologist Dr John Scott. As with other issues, climate change demands a complete rethink of how we deal with invasive plants and animals, he says. While invaders from overseas will remain ‘invaders’, more than 600 native Australian species have already colonised new areas of Australia: are they invaders or not?  “We need to understand and accept that our biodiversity is changing in profound ways– but clearly a vital goal will be to preserve its essential and unique Australian character,” says ecologist Dr Suzanne Prober. That will demand sharply increased vigilance on the biosecurity front, to keep invaders out. Related to this is the huge issue of how Australia’s food production systems adapt to climate change – some scientists fear that the agricultural intensification required to offset the effects of climate change on the food supply will come at a high cost to native ecosystems and biodiversity. Others think that agriculture may contract to more closely settled areas where soils and rainfall are better, leaving larger swathes of dry landscape to return to native bush or pastoralism. And still others believe Australian farming systems will become more closely integrated with native species – indeed, that we will increasingly farm indigenous plants and animals because of their ability to handle hot, dry times. We will increasingly value our native biota for the services they provide in protecting and buffering our landscapes and coasts, and in the genetic materials and technologies we can source as insurance for our own adaptation.    Marine and aquatic environments face changes no less great from the changing climate, says CSIRO marine scientist Dr Rodrigo Bustamante. “We estimate that in particular places up to a third of our coastal wetland could move from fresh-dominated to saltwater-dominated ecosystems. Many of them will be completely transformed and the species change will be extensive. We will also see the increasing ‘tropicalisation’ of our south-eastern and south-western coastlines as warmer water pushes further south: tropical species which are presently temporary visitors will establish further south and this will undoubtedly alter marine ecosystems. This is already happening on both sides of the continent and will bring novel challenges and opportunities to fisheries and aquaculture.” Perhaps the greatest change of all is the gradual acidification of the oceans, caused as human carbon dioxide emissions dissolve into them. This, says Dr Bustamante, has profound but as yet uncertain implications for the all marine organisms that build calcium carbonate shells and structures such as the planktonic coccolithophores which are at the foundation of oceanic food webs. “It likely means a major reorganisation of the ocean food chains, but the consequences for biodiversity and food production are not yet clear,” he adds.   Interpreting exactly what changes will occur is a task of extraordinary complexity, the scientists caution. Says Dr Michael Dunlop “First there is general uncertainty about how climate change will affect particular regions.  Second, there are many different types of impacts on species, ecosystems and landscapes. Third, interactions between species will change – this will amplify the effect of climate change for some species and ecosystems and reduce it for others. But trying to unravel this complexity at this time is not a fruitful path to pursue. The work of the climate adaptation scientist is to provide policy makers and land managers with the tools to make decisions despite the seemingly overwhelming sense of complexity and uncertainty. Craig James adds, “We know what aspects of climate change are certain such as sea level rise, warming and ocean acidification and can anticipate how these will affect species and ecosystems. Not all decisions need to be made right away.  Some decisions need to be made soon:  decisions that play out over long time frames like what species of trees to plant and where to plant them to get carbon sequestration and nest hollows for species over 100 years from now,. Other decisions can be deferred and made as we observe and learn about the changes, take stock of the situation both locally and across the continent and adapt our management of biodiversity to new unfolding situations.” Among such adaptations may be moving from a focus on trying to save individual species towards one of trying to build the resilience of total ecosystems, and from maintaining particular pockets to trying to better manage whole landscapes so as to blunt the stresses climate change will impose on them: these are the new scientific and policy issues that lie before us. The immediate outlook for Australian landscapes this century is one of considerable change through altered species composition and shifts from one set of dominant species to another set. By no means will all be lost, but future conservation programs will be confronted with the task of reducing species losses by managing ecological changes across the continent (rather than preventing changes in selected locations). The actions we undertake to retain as much of the essential Australian biodiversity as we can through the era of climate stress will be vital for maintaining the ecosystem services that we depend on every day, and essential to the future character of Australian life.

DDT still found in humans: study

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In a study of 146 human milk samples, most of the Persistent Organic Pollutants (POPs) found belonged to the DDT group. Image: PFleming/iStockphoto Despite being banned almost thirty years ago, the pesticide DDT is still being widely found in human bodies, a leading health researcher says. In a study of 146 human milk samples, most of the Persistent Organic Pollutants (POPs) found belonged to the DDT group, Professor Tze Wai Wong of The Chinese University of Hong Kong told the CleanUp 2011 Conference in Adelaide. “DDT was only one type of contaminant that we found,” says Prof. Wong. “There were also dioxins, other organochlorines and banned pesticides that were once widely used in agriculture. “Finding them in human milk indicates that these pollutants are still present in food chain, which means that they’re highly persistent and have a slow decline rate, or, worse still, they are still being used in some countries in food production– neither of which is good news for consumers.” Prof. Wong explains that human uptake of dioxins and other POPs is mostly from contaminated food products that originate from places with heavily polluted soil and water. Dioxins can also enter the body through contaminated air. “This problem is not confined to the Asia-Pacific, but can be found across the world. Apart from previous use of toxic pesticides, the community’s diet, its methods of waste disposal and its level of industrialisation can contribute to the uptake of POPs as well.” For example, nations that produce more industrial waste risk the contamination of marine products when the waste is dumped into the ocean, he says. Countries that incinerate their waste, like Japan or China, are particularly susceptible to dioxin contamination of food, as it is often released through burning. “We suspect that high concentrations of DDT will be found in communities which consume large amounts of seafood, dairy products, cattle and poultry, as animals tend to bioconcentrate these toxins,” he says. “In this case, Western Europe, Scandinavia and Japan are particularly at risk. “People in China and Japan may also have high concentrations of dioxin in their bodies, as waste is often incinerated which release this compound into the environment.” Prof. Wong says his research tends to show up pollutants which were present in the human environment decades ago, and are still around, rather than more recent contaminants. “We’re measuring what was prevalent in the past. Its persistence shows that we need to be cautious about what we are doing now, because the effects of today’s pollutants on health are not likely to be felt until some decades later.” Prof. Wong recommends increased vigilance in food production, and especially over attempts to introduce new chemical compounds into the food chain. “We have always been quick to come up with alternative chemicals to replace old or banned ones. This is often done without asking health researchers to examine their effects on the human body. Industry and scientists need to start working together better. “We also need to choose our food more wisely and rethink our dietary choices. Nutrition and flavour shouldn’t be our only considerations when planning meals. We also need to think about which foods may also contain high levels of contaminants.” It is also important to re-evaluate current methods of waste disposal, and their possible impact on human and environmental health, he says. “Eventually, everything that we use has to end up somewhere. We need to make sure that the human body doesn’t end up as the ‘last stop’ for toxic compounds.”

Hepatitis’ weak spots pinned

THE UNIVERSITY OF NEW SOUTH WALES

Finding the 'Achilles' heels' of the virus allows for the possible development of vaccines. Image: AlexRaths/iStockphoto Hopes for an effective vaccine and treatment against the potentially fatal hepatitis C infection have received a major boost following the discovery of two ‘Achilles’ heels’ within the virus. A team of medical researchers from the University of New South Wales (UNSW) studied individuals at high risk of hepatitis C (HCV) infection, including a number identified within a few weeks of the onset of infection. Using a new technique called next generation deep sequencing and sophisticated computer analytics the team, led by Professor Andrew Lloyd and Associate Professor Peter White, were able to identify the ‘founder’ virus responsible for the initial infection and then track changes within the virus as it was targeted by the immune system. “We discovered that hepatitis C has not one but two ‘Achilles’ heels’ that provide opportunities for vaccine development,” said Dr Fabio Luciani, from UNSW’s Inflammation and Infection Research Centre and the research team’s biostatistician. “If we can help the immune system to attack the virus at these weak points early on, then we could eliminate the infection in the body completely,” he said. A paper describing the breakthrough appears in the leading scientific journal in the field of virology, PLoS Pathogens. Hepatitis C virus infection is a global pandemic with more than 120 million people infected worldwide, including some 200,000 Australians. The virus causes progressive liver disease leading to cirrhosis, liver failure and cancer. Current antiviral treatments are arduous, costly, and only partially effective. Team member and virologist Dr Rowena Bull said the discovery of the weakest links meant vaccine researchers could now focus their attentions on the most likely avenues for success. “The first weak point was identified at transmission, when the virus has to survive the transfer from one individual to another,” Dr Bull said. “The second weakness, and surprise finding, was the significant drop in the diversity of the viral variants in each individual studied, occurring about three months after transmission, around the time where the immune system is starting to combat the virus. A lower number of variants means the virus is easier to target.” Study leader Professor Lloyd said the discoveries were significant because of their potential to overcome longstanding barriers to hepatitis C vaccine development. “To date hepatitis C has been difficult to target with single interventions because there are many different strains of the virus,” he said. “In addition, like HIV, the hepatitis C virus mutates very rapidly and exists as a complex family of mutated viruses within every infected individual, meaning the virus can avoid efforts by the immune system to keep it under control,” Professor Lloyd said. “What’s more, a third of infected people can have an effective immune response that eliminates the virus early on. This means key initial immune responses were difficult to identify and study because early infection and elimination can go unrecognised.” Professor Lloyd said work is now underway to identify the key immunological features of the founder viruses in order to guide new vaccines. “Further research will test the extent of the immune response against these founder viruses in a cohort of very early infected individuals,” he said. The research team included members from UNSW's Kirby Institute, The University of Western Australia and Murdoch University, and was supported by a National Health and Medical Research Council of Australia (NHMRC) Program Grant and by grants from Australian Centre for HIV and Hepatitis Virology.

E-waste ‘may spread worldwide’

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Thousands of tonnes of toxic e-waste are entering the world’s atmosphere, oceans, fresh waters, soils and foodstuffs every year. Image: DonNichols/iStockphoto So dire is the electronic waste contamination problem in Asia that it can potentially spread worldwide, a leading environmental researcher told the CleanUp 2011 Conference in Adelaide today. Professor Ming Hung Wong from Hong Kong Baptist University says that the illegal shipping of e-waste to developing countries in recent decades, coupled with inadequate handling and disposal methods, can potentially return the pollutants to developed nations. Thousands of tonnes of toxic e-waste are entering the world’s atmosphere, oceans, fresh waters, soils and foodstuffs every year. This is now spreading round the planet, including back to the societies that originally produced them. Using China as an example, Prof. Wong says that it used to be a popular dumping site for e-waste, with 70 per cent of the world’s e-waste sent there: “In recent years, a lot of these waste products have been rejected due to stricter rules. However, these shipments are either abandoned in Hong Kong, or now find their way to other countries, such as Pakistan or India. “In 2009 alone, 53 million tonnes of e-waste were generated worldwide. It’s the fastest growing waste source in the world, which includes discarded products such as computers, refrigerators, phones, televisions, printers and more.” In spite of the development of newer technology and methods to recycle e-waste, the recycling process in many developing regions is still primitive, with few or no facilities or trained professionals to ensure safe disposal of toxic products, he says. Piles of wire with plastic casings are often burned to recover the metal, and circuit boards are slowly grilled over coal to release valuable chips. “The slow burning of these products releases large quantities of hazardous chemicals to the surroundings, while the ashes are often contaminated with lead and other metals,” he says. “These persistent pollutants end up everywhere – the air, the ocean, or leak into soil and groundwater. This problem has been identified in China, the Philippines, Vietnam, Pakistan and India. “It’s no longer a problem that is confined to the villages that deal with e-waste, because when water and soil is polluted, everyone is vulnerable to the food products that are exported from these regions. “The adverse health effects of the workers and residents of the e-waste recycling sites, due to various toxic chemicals have been demonstrated by different studies. What is more important is that these chemicals are transferred to the next generation through pregnant mothers – placenta transfer – and lactating mothers through breast feeding." Steps have been taken by some manufacturers to reduce the generation of hazardous e-waste in the first place, Prof. Wong says, but vigilance and rigorous surveillance are necessary to ensure that they all adhere to the rules and stop shipping e-waste to Asia. “Although some hazardous chemicals, including flame-retardants and heavy metals such as mercury, chromium, cadmium, and lead have been banned from use in the manufacture of electrical and electronic equipment (EEE), these regulations were set five years ago, which means that we still have a vast amount of older electrical and electronic equipment once they’re discarded. “The key is to ensure that e-waste is not smuggled from developed countries to poorer nations where they dispose of it with out-dated and unsafe methods. This includes validating that products labelled ‘re-usable’ are genuinely so, and not simply disguised as such when they are really intended for recycling." Prof. Wong says the world should consider imposing a tax on all EEE to ensure that when the equipment is discarded, the cost of recycling it properly is covered. “This is a worldwide problem where everyone should take heed, because the lifespan of EEEs is getting shorter, and the turnover rates are faster. This means we are producing more and more toxic contaminants every year – and they have to end up somewhere.”

New barrier keeps water clean

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The contaminants of groundwater can be mixed with the local water supply without proper sanitation.  Image: aristotoo/iStockphoto As the world’s cities grow to depend increasingly on underground water for drinking and domestic use, better methods are needed to keep it safe from contamination, the CleanUp 2011 conference heard today. Underground barriers – known as permeable reactive barriers or PRBs – offer a reliable and affordable way to prevent industrial and other forms of toxic pollution from entering the water supply, says Scott Warner, Vice President and Principal Hydrogeologist with the international engineering and project management company AMEC which has offices worldwide and in Australia. “PRB technology was first applied commercially in California in 1994, and today there are more than 200 barriers installed across North America, Europe, Japan, and Australia,” Mr Warner says. “It is now an accepted and proven technology for passively treating a wide variety of chemicals, including organic solvents, metals, and radionuclides.” PRBs usually consist of an underground barrier filled with material to neutralise contaminants, built across the path of a contaminated groundwater plume. They are designed to intercept and clean up the water before it can enter aquifers used for urban supply, wells, lakes or shorelines. The barrier operates using the natural flow of the groundwater, without the need of power to run it. “Contaminated groundwater exists on every continent and, particularly where sanitation is lacking or nonexistent, the contaminants can become well mixed with the local water supply,” Mr Warner says. “Groundwater contamination continues to be a serious problem worldwide for urban, rural and undeveloped areas. Sources of contamination include not just industrial releases, but also runoff from agricultural lands, mining sites, landfills, and urban zones. Many cities primarily rely on ground water for drinking water and other potable uses and generally arid countries such as Australia have seen a rapid increase in the use of groundwater.” The barrier may contain a range of low-cost materials designed to absorb or immobilise contaminants from the ground water as it passes through. These include bio-mulches for removing toxic metals and granular iron, which is used to destroy organic chemicals. “PRBs are not the solution to every contamination problem. They must be designed for a specific site and its contaminants and are mainly effective at relatively shallow depths, up to 30 metres,” he says. “Recent years have seen a number of advances in PRB design that can assure a long-lasting remedy. The modern PRB is quite reliable, providing the system is designed to work with the site specific conditions, including geological, hydrological, chemical and land use characteristics.” Newer designs include the use of deep, and closely spaced large diameter borings filled with treatment media; mulch bio-walls that can be replenished, and dual-wall PRBs that can treat multiple contaminants. New methods for inject PRB material into deep systems, and one-pass trenching machines are also helping to reduce costs. Mr Warner says that a PRB can pay for itself in a few years, in contrast to more costly pump-and-treat systems for cleansing groundwater which require energy to run them. Over a lifetime a PRB can save millions of dollars. As the world’s city populations soar to 7 billion or more in the mid-century, this will create new uses for PRBs, he anticipates. “While cities continue to grow, the expansion of the urban footprint to undeveloped areas, or the need to mitigate groundwater impacted by old mines, agricultural fields, or poor sanitation systems will continue to push research into new groundwater remedies; remedies that are economical, sustainable, resource conservative, and relatively easy to maintain and operate. “The PRB is a key tool available for us to use to effectively remove contaminants from groundwater, while the water is still in the ground.”

In the Early Life of an Embryo, a Monster Lurks: Newly Fertilized Cells Only Narrowly Avoid Degenerating Into Fatal Chaos

Science Daily  — Research based at Princeton University has revealed that newly fertilized cells only narrowly avoid degenerating into fatal chaos. At the same time, scientists have discovered that embryos have acquired a mechanism to contain this dangerous instability, a finding that could help biologists unravel other mysteries about the first hours of life.

This lurking state of disorder was revealed through computational models the researchers constructed of the embryo cell cycle. The cell cycle is the repeated division and duplication of cells that transform a single fertilized egg into a full-grown organism. Scientists already knew that embryonic cell cycles are initiated by a swift wave of calcium that emanates from the fertilization site and prompts the embryo's cells to divide and duplicate -- or oscillate, in biological terms.

A team led by Princeton Professor of Molecular Biology Ned Wingreen reported recently in the journal PLoS Computational Biology that contrary to the idea that embryonic cells develop in natural synchrony, they are prone to descend into disarray. Without stabilization, cells develop on different schedules, and many stop developing altogether, which threatens the embryo's survival.

A natural assumption among scientists had been that once initiated, the impulse to oscillate would ripple across the embryo -- which begins as one big cell that then divides repeatedly -- and set the stage for multiple rounds of cell division to occur in sync. Wingreen and his colleagues found, however, that the natural spread of oscillation is unstable and would result in an erratic patchwork of missed and incomplete cell divisions. They predicted that cell activity instead has to be triggered throughout the embryo at almost exactly the same time.

The researchers' simulation produced the first indication that the fast-moving calcium wave known to spark cell division doubles as a synchronizer that sets cells to the same developmental timetable. The finding revealed a crucial role for the somewhat puzzling existence of the calcium wave, as well as a new level of sophistication in how embryos function.

"We didn't have to go searching for chaos, it just came right out at us," Wingreen said. "When the dust settled, it became clear that cell-cycle oscillation, while remarkably uniform in the end, does not come by that harmony on its own, especially not in anything as big as an embryo, which is much larger than a typical cell. But then the question became, if there's this potential for chaos, how does the system avoid it? It turns out that the system needs the calcium wave to avoid chaos and that wave is activated surprisingly fast."

The embryo's need for stabilization and the dual role of the calcium wave illuminates the intricacy of developing embryos, as well as the impressive ability of embryos to prevent their own destruction, said James Ferrell, a Stanford University professor of chemical and systems biology. The Princeton researchers based their work on formulas that Ferrell developed from experiments on African clawed frog embryos that describe how embryos divide and replicate in timed cycles during early development.

"One of this group's conclusions is that chaos lurks not far from where the system normally functions, like a monster in the corner and that it matters to have synchronicity established quickly to prevent it. That's not something we had initially thought about," said Ferrell, who had no involvement in the Princeton-led research, but is interested in testing the results experimentally.

"They present a nice story of how evolution has come up with a way to do things as fast as is needed to avoid chaos, but not too much faster. It's deepened our appreciation of what is happening in the biological system, and is a good example of how theory and careful modelling can reveal functions that might not appear in experiments."

Wingreen, a theoretical biologist and associate director of Princeton's Lewis-Sigler Institute for Integrative Genomics, initiated the project when he noticed that existing cell-cycle formulas and models such as Ferrell's did not explain how embryos keep cell activity synchronized across their considerable girth. Embryos are huge, about 10 to 100 times larger than a normal cell, he said, and at that size, oscillation would not necessarily fan out from the point of fertilization, as was assumed. Instead, the process would be vulnerable to any bump in the cellular road and would splinter into patches of disarray, he said.

In theory, chaos could be avoided if oscillation spread quickly enough, Wingreen said. But the cell cycle is driven by an intricate exchange of proteins with its own schedule. Wingreen doubted that this activity could spread itself across an expansive embryo fast enough, especially as the embryo grows. He wanted to take the embryo's size into account as a factor in the spread of cell activity, which no published cell-cycle models had considered.

Wingreen and the paper's lead author, Scott McIsaac, a doctoral student in Princeton's Lewis-Sigler Institute, altered Ferrell's cell-cycle equations so that oscillation would spread across the expanse of an embryo. They worked with co-author K.C. Huang, a Stanford assistant professor of bioengineering, to solve the revised formulas in a three-dimensional model. Co-author Anirvan Sengupta, a professor of physics and astronomy at Rutgers University, characterized and analyzed the various instabilities that might occur as the simulated embryonic cells divided.

"We had no clear idea of what adding a spatial element would produce," Wingreen said. "I was interested if there was an inhomogeneous element to cell-cycle oscillation, if the cells in fact did not all act in unison. My training is in physics, and I know that whenever you add a new dimension, interesting things can happen. I had a feeling something would happen if we ran these formulas in a spatially extended system."

The initial simulation tested how cell activity would spread through the embryo solely by diffusion. Oscillation indeed found its way across the cell, but disorder took root almost instantly. Cells divided at different speeds, with many left undeveloped by the end of the cycle. As the simulation went on for 200 minutes, the mayhem grew worse. A real embryo would not survive this breakdown, or would at least be left with severe developmental problems, Wingreen said.

Wingreen and McIsaac began to suspect that the calcium wave had a role in keeping the cellular peace. Although known to spark cell cycles, the full purpose of the calcium wave had previously had some shadow of mystery, Wingreen said. But once the team ruled out that cell activity could self-regulate, they knew something else brought order to the developing embryo. The calcium wave -- which spreads across the embryo rapidly following fertilization -- seemed a likely candidate.

The researchers then simulated cell division with fast and slow calcium waves. Slow waves creeping at 1 millimeter every 10 minutes opened the door for havoc. However, when sped up in the simulation to travel a millimeter in four minutes, the calcium wave synchronized cell activity, and the embryo developed normally. The simulation exposed the calcium wave as not only an initiator of embryo development but also a regulator of that activity.

If the calcium wave doubles as a regulator, then it could have other functions. Moreover, other mechanisms that seemingly serve one purpose may also have others. These possible extra duties could be behind other happenings in embryo cells that are not well understood, said Eric Wieschaus, the Squibb Professor of Molecular Biology at Princeton and a 1995 Nobel Prize winner.

"The fact that the system generally doesn't devolve into chaos might mean that embryos have developed additional mechanisms that we don't know about. It would be interesting to know what those mechanisms are," Wieschaus said.

"From my own standpoint, the paper makes me want to check back through mutant lines that disrupt development and have never been fully described or understood, but might be affected in this process. This model gives a sense of what to look for, and that is always valuable."

Just as the experiment-based models developed by Stanford's Ferrell fueled Wingreen's work, Wingreen hopes his models can guide further study of embryo development in the laboratory. He said the next steps are to reproduce the simulations in actual embryos, and to test the limits of calcium-wave synchronization to learn if it holds up when development on one side of an embryo is slowed, or if the two halves of a split embryo would remain coordinated.

"These are all experimental steps," Wingreen said. "My group does theory and modeling, so our hope is that we've put the ball back in the experimentalists' court."

The research, reported in the July issue of PLoS Computational Biology, was funded by grants from the National Science Foundation and the National Institutes of Health.

Bats Adjust Their 'Field-Of-View': Use of Biosonar Is More Advanced Than Thought

Science Daily  — A new study reveals that the way fruit bats use biosonar to 'see' their surroundings is significantly more advanced than first thought.

The research team, led by Nachum Ulanovsky of the Weizmann Institute in Israel and Cynthia Moss of the University of Maryland, reports that these bats adapt to environmental complexity using two tactics. First, they alter the width of their sonar beam, similar to the way humans can adjust their spotlight of attention in order to spot, for example, a friend in a crowded room. Second, they modify the intensity of their emissions. "The work presented here reveals a new parameter under adaptive control in bat echolocation," says Ulanovsky.

The study, published Sept. 13 in the online, open access journal PLoS Biology, examines Egyptian fruit bats (Rousettus aegyptiacus), which use echolocation to orient inside their caves and to find fruit hidden in the branches of trees. Their high-frequency clicks form a sonar beam that spreads across a fan-shaped area, and the returning echoes allow them to locate and identify objects in that region. As these bats were considered to have little control over their vocalizations, scientists have puzzled over how they are able to navigate through complex environments.

Ulanovsky and his team trained five Egyptian fruit bats to locate and land on a mango-sized plastic sphere placed in various locations in a large, dark room equipped with an array of 20 microphones that recorded vocalizations. In one set of experiments, the researchers simulated an obstacle-filled forest by surrounding the sphere with two nets spread between four poles. To reach the target, the bats flew through a narrow corridor whose width and orientation varied from trial to trial.

In the obstacle-filled environment, the bats covered three times as much area with each pair of clicks as they did when the obstacles weren't there. The angle separating each two beams was also wider and the volume of the clicks louder, and these differences became more pronounced as they drew further into the corridor and therefore closer to their obstacles. This larger 'field of view' allowed the bats to track the sphere and the poles simultaneously, and avoid collisions while landing.

"This is the first report, in any sensory system, of an active increase in field-of-view in response to changes in environmental complexity," says Ulanovsky. Although these new findings may be unique to Egyptian fruit bats because of their rapid tongue movements, Ulanovsky explains that their results "suggest that active sensing of space by animals can be much more sophisticated than previously thought -- and they call for a re-examination of current theories of spatial orientation and perception."

Fathers Wired to Provide Offspring Care; Study Confirms That Testosterone Drops Steeply After Baby Arrives

Human males are biologically wired to care for their offspring, new research confirms. (Credit: © Melissa Schalke / Fotolia)

Science Daily  — A new Northwestern University study provides compelling evidence that human males are biologically wired to care for their offspring, conclusively showing for the first time that fatherhood lowers a man's testosterone levels.

Humans are unusual among mammals in that our offspring are dependent upon older individuals for feeding and protection for more than a decade," said Christopher W. Kuzawa, co-author of the study and associate professor of anthropology in the Weinberg College of Arts and Sciences. He also is a faculty fellow at the Institute for Policy Research at Northwestern. "Raising human offspring is such an effort that it is cooperative by necessity, and our study shows that human fathers are biologically wired to help with the job."

The effect is consistent with what is observed in many other species in which males help take care of dependent offspring. Testosterone boosts behaviors and other traits that help a male compete for a mate. After they succeed and become fathers, "mating-related" activities may conflict with the responsibilities of fatherhood, making it advantageous for the body to reduce production of the hormone.

Past studies showing that fathers tend to have lower testosterone levels were small and not conclusive regarding whether fatherhood diminished testosterone or whether men with low testosterone in the first place were more likely to become fathers. The new study takes a novel approach by following a large group of men who were not fathers and seeing whether their hormones changed after becoming fathers.

"It's not the case that men with lower testosterone are simply more likely to become fathers," said Lee Gettler, a doctoral candidate in anthropology at Northwestern and co-author of the study. "On the contrary, the men who started with high testosterone were more likely to become fathers, but once they did, their testosterone went down substantially. Our findings suggest that this is especially true for fathers who become the most involved with child care."

The new study's findings also suggest that fathers may experience an especially large, but temporary, decline in testosterone when they first bring home a newborn baby. "Fatherhood and the demands of having a newborn baby require many emotional, psychological and physical adjustments," Gettler said. "Our study indicates that a man's biology can change substantially to help meet those demands."

The authors also suggest that their findings may provide insight into one reason why single men often have poorer health than married men and fathers. "If fathers have lower testosterone levels, this might protect them against certain chronic diseases as they age," Kuzawa said.

The study followed a group of 624 males aged 21.5 to 26 years old for 4.5 years in the Philippines.

The study was published Sept. 12, 2011, in the Proceedings of the National Academy of Sciences.

The study's co-authors, along with Gettler and Kuzawa, are Thomas W. McDade, professor of anthropology and Institute for Policy Research faculty fellow, Northwestern University, and Alan Feranil, director, Office of Population Studies Foundation, University of San Carlos, Cebu City, Philippines. The research was funded by the National Science Foundation and the Wenner Gren Foundation.

Star Blasts Planet With X-Rays

This graphic contains an image and illustration of a nearby star, named CoRoT-2a, and an orbiting planet known as CoRoT-2b. The image contains X-rays from Chandra (purple) of CoRoT-2a along with optical and infrared data of the field of view in which it is found. CoRoT-2b, which is not seen in this image, orbits extremely closely to the star. In fact, the separation between the star and planet is only about 3 percent of the distance between the Earth and the Sun. The Chandra data indicate that planet is being blasted by X-rays with such intensity that some 5 millions of tons of material are being eroded from the planet every second. (Credit: Optical: NASA/NSF/IPAC-Caltech/UMass/2MASS, PROMPT; Wide field image: DSS; X-ray: NASA/CXC/Univ of Hamburg/S.Schröter et al; Illustration: CXC/M. Weiss)

Science Daily — A nearby star is pummeling a companion planet with a barrage of X-rays a hundred thousand times more intense than Earth receives from the Sun.

The planet, known as CoRoT-2b, has a mass about 3 times that of Jupiter (1000 times that of 


Earth) and orbits its parent star, CoRoT-2a at a distance roughly ten times the distance 


between Earth and the Moon.

New data from NASA's Chandra X-ray Observatory and the European Southern Observatory's Very Large Telescope suggest that high-energy radiation is evaporating about 5 million tons of matter from the planet every second. This result gives insight into the difficult survival path for some planets.

The CoRoT-2 star and planet -- so named because the French Space Agency's Convection, Rotation and planetary Transits (CoRoT) satellite discovered them in 2008 -- is a relatively nearby neighbor of the Solar System at a distance of 880 light years.

"This planet is being absolutely fried by its star," said Sebastian Schroeter of the University of Hamburg in Germany. "What may be even stranger is that this planet may be affecting the behavior of the star that is blasting it."

According to optical and X-ray data, the CoRoT-2 system is estimated to be between about 100 million and 300 million years old, meaning that the star is fully formed. The Chandra observations show that CoRoT-2a is a very active star, with bright X-ray emission produced by powerful, turbulent magnetic fields. Such strong activity is usually found in much younger stars.

"Because this planet is so close to the star, it may be speeding up the star's rotation and that could be keeping its magnetic fields active," said co-author Stefan Czesla, also from the University of Hamburg. "If it wasn't for the planet, this star might have left behind the volatility of its youth millions of years ago."

Support for this idea come from observations of a likely companion star that orbits CoRoT-2a at a distance about a thousand times greater than the separation between Earth and our Sun. This star is not detected in X-rays, perhaps because it does not have a close-in planet like CoRoT-2b to cause it to stay active.

Another intriguing aspect of CoRoT-2b is that it appears to be unusually inflated for a planet in its position.

"We're not exactly sure of all the effects this type of heavy X-ray storm would have on a planet, but it could be responsible for the bloating we see in CoRoT-2b," said Schroeter. "We are just beginning to learn about what happens to exoplanets in these extreme environments."

These results were published in the August issue of Astronomy and Astrophysics. The other co-authors were Uwe Wolter, Holger Mueller, Klaus Huber and Juergen Schmitt, all from the University of Hamburg.

Astronomers Find Extreme Weather On an Alien World: Cosmic Oddball May Harbor a Gigantic Storm

Astronomers have observed extreme brightness changes on a nearby brown dwarf that may indicate a storm grander than any seen yet on a planet. This finding could new shed light on the atmospheres and weather on extra-solar planets. (Credit: Art by Jon Lomberg)

Science Daily — A University of Toronto-led team of astronomers has observed extreme brightness changes on a nearby brown dwarf that may indicate a storm grander than any seen yet on a planet. Because old brown dwarfs and giant planets have similar atmospheres, this finding could shed new light on weather phenomena of extra-solar planets.

As part of a large survey of nearby brown dwarfs -- objects that occupy the mass gap between dwarf stars and giant planets -- the scientists used an infrared camera on the 2.5m telescope at Las Campanas Observatory in Chile to capture repeated images of a brown dwarf dubbed 2MASS J21392676+0220226, or 2MASS 2139 for short, over several hours. In that short time span, they recorded the largest variations in brightness ever seen on a cool brown dwarf.

"We found that our target's brightness changed by a whopping 30 per cent in just under eight hours," said PhD candidate Jacqueline Radigan, lead author of a paper to be presented this week at the Extreme Solar Systems II conference in Jackson Hole, Wyoming and submitted to the Astrophysical Journal. "The best explanation is that brighter and darker patches of its atmosphere are coming into our view as the brown dwarf spins on its axis," said Radigan.

"We might be looking at a gigantic storm raging on this brown dwarf, perhaps a grander version of the Great Red Spot on Jupiter in our own solar system, or we may be seeing the hotter, deeper layers of its atmosphere through big holes in the cloud deck," said co-author Professor Ray Jayawardhana, Canada Research Chair in Observational Astrophysics at the University of Toronto and author of the recent book Strange New Worlds: The Search for Alien Planets and Life beyond Our Solar System.

According to theoretical models, clouds form in brown dwarf and giant planet atmospheres when tiny dust grains made of silicates and metals condense. The depth and profile of 2MASS 2139's brightness variations changed over weeks and months, suggesting that cloud patterns in its atmosphere are evolving with time.

"Measuring how quickly cloud features change in brown dwarf atmospheres may allow us to infer atmospheric wind speeds eventually and teach us about how winds are generated in brown dwarf and planetary atmospheres," Radigan added.

Other co-authors of this work are David Lafrenière and Étienne Artigau at the Université de Montreal, Didier Saumon at Los Alamos National Laboratory, and Mark Marely at NASA Ames Research Center.

The research was supported by a Vanier Canada Graduate Scholarship awarded to Radigan, and a Research Tools and Instrumentation grant, a Discovery grant, a Steacie Fellowship and the Canada Research Chairs program, all awarded to Jayawardhana from the Natural Sciences and Engineering Research Council of Canada.

Ferroelectrics Could Pave Way for Ultra-Low Power Computing

Shown is a rendition of an experimental stack made with a layer of lead zirconate titanate, a ferroelectric material. UC Berkeley researchers showed that this configuration could amplify the charge in the layer of strontium titanate for a given voltage, a phenomenon known as negative capacitance. (Credit: Asif Khan, UC Berkeley)

Science Daily — Engineers at the University of California, Berkeley, have shown that it is possible to reduce the minimum voltage necessary to store charge in a capacitor, an achievement that could reduce the power draw and heat generation of today's electronics.

Khan, working in the lab of Sayeef Salahuddin, UC Berkeley assistant professor of electrical engineering and computer sciences, has been leading a project since 2008 to improve the efficiency of transistors."Just like a Formula One car, the faster you run your computer, the hotter it gets. So the key to having a fast microprocessor is to make its building block, the transistor, more energy efficient," said Asif Khan, UC Berkeley graduate student in electrical engineering and computer sciences. "Unfortunately, a transistor's power supply voltage, analogous to a car's fuel, has been stuck at 1 volt for about 10 years due to the fundamental physics of its operation. Transistors have not become as 'fuel-efficient' as they need to be to keep up with the market's thirst for more computing speed, resulting in a cumulative and unsustainable increase in the power draw of microprocessors. We think we can change that."The researchers took advantage of the exotic characteristics of ferroelectrics, a class of material that holds both positive and negative electrical charges. Ferroelectrics hold electrical charge even when you don't apply a voltage to it. What's more, the electrical polarization in ferroelectrics can be reversed with the application of an external electrical field.

Getting more bang for the buck

The engineers demonstrated for the first time that in a capacitor made with a ferroelectric material paired with a dielectric -- an electrical insulator -- the charge accumulated for a given voltage can, in effect, be amplified, a phenomenon called negative capacitance.

The team report their results in the Sept. 12 issue of the journalApplied Physics Letters. The experiment sets the stage for a major upgrade to transistors, the on-off switch that generate the zeros and ones of a computer's binary language.

"This work is the proof-of-principle we have needed to pursue negative capacitance as a viable strategy to overcome the power draw of today's transistors," said Salahuddin, who first theorized the existence of negative capacitance in ferroelectric materials as a graduate student with engineering professor Supriyo Datta at Purdue University. "If we can use this to create low-power transistors without compromising performance and the speed at which they work, it could change the whole computing industry."

The researchers paired a ferroelectric material, lead zirconate titanate (PZT), with an insulating dielectric, strontium titanate (STO), to create a bilayer stack. They applied voltage to this PZT-STO structure, as well as to a layer of STO alone, and compared the amount of charge stored in both devices.

"There was an expected voltage drop to obtain a specific charge with the dielectric material," said Salahuddin. "But with the ferroelectric structure, we demonstrated a two-fold voltage enhancement in the charge for the same voltage, and that increase could potentially go significantly higher."

Computer clock speed hits a bottleneck

Since the first commercial microprocessors came onto the scene in the early 1970s, the number of transistors squeezed onto a computer chip has doubled every two years, a progression predicted by Intel co-founder Gordon Moore and popularly known as Moore's Law. Integrated circuits that once held thousands of transistors decades ago now boast billions of the components.

But the reduced size has not led to a proportional decrease in the overall power required to operate a computer chip. At room temperature, a minimum of 60 millivolts is required to increase by tenfold the amount of electrical current flowing through a transistor. Since the difference between a transistor's on and off states must be significant, it can take at least 1 volt to operate a transistor, the researchers said.

"We've hit a bottleneck," said Khan. "The clock speed of microprocessors has plateaued since 2005, and shrinking transistors further has become difficult."

The researchers noted that it becomes increasingly difficult to dissipate heat efficiently from smaller spaces, so reducing transistor size much more would come at the risk of frying the circuit board.

The solution proposed by Salahuddin and his team is to modify current transistors so that they incorporate ferroelectric materials in their design, a change that could potentially generate a larger charge from a smaller voltage. This would allow engineers to make a transistor that dissipates less heat, and the shrinking of this key computer component could continue.

Notably, the material system the UC Berkeley researchers reported shows this effect at above 200 degrees Celsius, much hotter than the 85 degrees Celsius (185 degrees Fahrenheit) at which a current day microprocessor works.

The researchers are now exploring new ferroelectric materials for room temperature negative capacitance in addition to incorporating the materials into a new transistor.

Until then, Salahuddin noted that there are other potential applications for ferroelectrics in electronics. "This is a good system for dynamic random access memories, energy storage devices, super-capacitors that charge electric cars, and power capacitors for use in radio frequency communications," he said.

This research was supported by the Semiconductor Research Corporation's Focus Center Research Program and the Office of Naval Research.