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By Stephen Luntz

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Kiwi Gender Defies Temperature Effect
Gender ratios among New Zealand children are not dependent on temperature, a study has found.

The result at first seems barely worth noting; while many reptiles use temperature to determine the sex of their offspring (AS, Jan/Feb 2011, p.7), mammals generally do not. However, studies have found subtle relationships between temperature and the ratio of male to female births around the world.

According to Dr Barnaby Dixson of Victoria University’s School of Biological Sciences, studies in northern Europe have reported fewer males born after particularly cold winters. Male babies are also less likely to survive in cold years.

This fits with widespread evidence that male human foetuses are more prone to stress than females. On the other hand, aside from regions where sex-selective abortions are common, a lower proportion of live births are male in tropical regions, suggesting that heat may have an even more potent effect.

Dixson set out to test how New Zealand fits into this, comparing average temperature records with birth data. Only 51.3% of New Zealand live births over the past 135 years have been male compared with 51.7% worldwide, but Dixson says that “colder years or seasons had no influence on this percentage”.

Thinking that the areas most New Zealanders inhabit may not get cold enough to show an effect, Dixson compared New Zealand’s Southland and Northland regions. “The two areas have dramatically different ambient temperatures but there was no difference in the likelihood of having a male or a female baby,” he says.

Dixson is not deterred by the failure to find a weather-related pattern in his home country and is looking further afield. “Australia has much greater temperature variations than New Zealand and, in some areas, is hot enough that heat stress may impact on the gender of babies,” Dixson says. He is currently conducting an analysis of Australian birth data and weather records.

Other researchers are investigating alternative factors that may influence sex selection. Just as diet may influence sheep offspring (AS, November 2011, p.10), some studies have been reporting a similar, if more subtle, effect in humans. However, Dixson says that this idea is still highly contentious, with many responses criticising the methodology and sample size of these studies.

Dixson’s research has been published in PLoS One.

Path to Preventing Cancer Regrowth
A new technique for fighting small cell lung cancer (SCLC) could have applications against many tumours but will require a redesign of clinical trials to bring it to market.

“Traditional chemotherapy relies on blasting a tumour until it is as small as possible,” says Prof Neil Watkins of the Monash Institute of Medical Research. While this works well for some cancers, 90% of SCLC patients will relapse within 12 months. Moreover, the regrowth is different from the original cancer and harder to treat.

Watkins has found that the regrowing SCLCs are very dependent on a signalling pathway known as hedgehog. The pathway is highly conserved across species; its name arose because a variant form of the controlling gene causes the growth of spiky bristles on fruit flies.

“If you regenerate cells from healthy tissue they rely on a different signalling pathway,” Watkins explains. “It’s like the difference between adult cells and stem cells.”

Watkins decided to put this knowledge into a cancer model, theorising that the hedgehog pathway, which is important in tissue regeneration, might be significant when cancers are reduced to the smallest population of cells. He has confirmed the activity of the hedgehog pathway in SCLC regrowth in Nature Medicine.

Hedgehog inhibitors exist in plants, and pharmaceutical companies are now producing their own versions. Interfering with a pathway used by tissue cells to recover carries obvious risks, but Watkins says that only hair cells appear to have a high level of dependence on hedgehog. Consequently, cancer patients treated with hedgehog inhibitors are likely to suffer much longer-term hair loss than those undergoing traditional chemotherapy, but Watkins hopes they will suffer only minor damage to more vital organs.

SCLC is a particularly easy form of cancer to study since it is highly responsive to initial treatment but rebounds so strongly. Nevertheless, Watkins says the hedgehog pathway has been identified in forms of resurgent leukaemia.

“The work could have applications more widely than just SCLC and more widely than just hedgehog,” Watkins says. For example, he believes that other embryonic-derived pathways may be effective in preventing the regrowth of ovarian cancers.

Before treatments can come to market, however, clinical trials will be needed. Dr Vinod Ganju of the Monash Cancer Centre says: “Based on this research, we need to change our approach. We will redesign our clinical trials to test how these new therapies can improve patient outcomes following chemotherapy.”

Traditional chemotherapy trial techniques that rely on measuring shrinking tumours will not work, forcing longer and more expensive studies using statistical measurements of patients in remission to see if hedgehog inhibitors produce longer survival times.

Logged Forests Reach “Tipping Point” for Mega Fires
The logging of Victoria’s mountain ash forests has transformed the entire region from fire-resistant to fire-prone. Some of the world’s leading ecologists warn that further fires could replace the tallest flowering plants on the planet with an ecosystem dominated by wattle, depriving Melbourne of its primary water supply.

Prof David Lindenmayer of the Australian National University considers the findings so important he paid for open access publication of the findings in the Proceedings of the National Academies of Science “out of my own pocket”. Publicity on radio and television has led to hate mail, but Lindenmayer believes it is vitally important that the nation responds to the research.

“Before European settlement, the fire regime was dominated by an infrequent severe wildfire that occurred in late summer,” Lindenmayer explains. “Young seedlings germinate from seed released from the crowns of burned mature trees to produce a new, even-aged stand.

“What we are now realising is the combination of wildfire and logging is creating a previously unrecognised landscape trap in which the behaviour of ash forest landscapes is markedly different from that which would have occurred before European settlement. The core process underlying this landscape trap is a positive feedback loop between fire frequency and severity and a reduction in forest age at the stand and landscape levels caused by logging.”

The idea that young forest stands are more prone to fire is not new, but Lindenmayer says it is only since Victoria’s Black Saturday fires in 2009 that researchers have realised this has reached a tipping point where “the whole landscape is at risk of being consumed by mega fires”.

The research came about when Lindenmayer was challenged by a forestry supporter who alleged that, if it were not for environmentalists preventing logging, the 2009 fires would not have occurred. Lindenmayer responded that he did not know what the relationship was between logging and fire, and started to investigate. He found research dating back to the 1990s showing that, when tropical rainforests are opened up to logging, more forest is eventually lost to increased fires than to logging itself.

Research in temperate areas was less developed, but indicated that the same issues might arise in wet forests. Lindenmayer drew leading scientists from around the world into a collaboration that may transform the way temperate wet forests are viewed worldwide.

Lindenmayer realised that just 1.2% of the old growth mountain ash forests existing prior to European arrival survives. Young forest rebounding from logging and fire needs decades without exposure to either if it is to gain fire resistance. Lindenmayer considers this “very unlikely”. Every fire or logging operation resets the clock, endangering all the areas around the affected territory.

Another major fire so soon after the last one will prevent even young mountain ash from appearing, leading to an environment dominated by wattle scrub.

Young forests hold far less carbon than old growth forests, and also release less of the water on which Melbourne depends.

Some non-scientists have suggested that the forests should be removed entirely and replaced with regularly burned grasslands or concrete to keep Melbourne’s fringes safe from fires. However, Lindenmayer points out that forests are part of a cycle with the clouds, and their removal would destroy Melbourne’s water catchments.

The outcome looks set to become an archetype of ecologies whose resilience is worn away by repeated attack, flipping suddenly into another state from which they can only be restored through the input of much energy (AS, May 2002, pp.39–40). However, Lindenmayer is unsure what, if anything, could be done to restore the forests to their previous state. “I don’t know, and I should,” he says. “I need to do some deep thinking.”

Cancer Research Ecstasy
Chemicals based on the party drug MDMA, which is popularly known as ecstasy, have the potential to kill blood cancers, including some that are highly resistant to current treatments.

A/Prof Matthew Piggott of the University of Western Australia’s School of Biomedical, Biomolecular and Chemical Sciences has been exploring the potential of MDMA to treat Parkinson’s disease.

Separately a University of Birmingham team led by Prof John Gordon has been exploring similarities in the signalling of brain and immune system cells, and found that certain receptors and transmitters are common to both. When Gordon tested chemicals that affect serotonin signalling in the brain against blood cell lines, he found that MDMA is weakly toxic to blood cancers.

“We contacted Prof Gordon as we already had several MDMA analogues – initially created for Parkinson’s disease treatment research – ready to go and he was very keen to test these on his cell lines,” Piggott says. “We found one that was ten times more potent, so we designed other chemicals based on this and a few of these are ten times more potent again.”

But even this 100-fold increase in effectiveness is insufficient. “We probably need another tenfold increase in potency before we are ready to try the drug candidate in an animal model of blood cancer,” Piggott says.

If such an increase can be achieved, drugs based on the MDMA structure may be useful against a broad range of cancers. “They kill cancers that express the protein BCL-2 and those that don’t,” Piggott says. “Current cancer chemotherapeutics generally don’t work well against BCL-2-expressing cancers.”

The MDMA analogues are non-toxic to other types of cells, suggesting they may have fewer side-effects than current anti-cancer drugs.

Since the researchers do not know the mode of action of the MDMA analogues, there is much trial and error in the process of discovering new drug candidates. However, they have found some guidance in the controversial research conducted by Dr Alexander Shulgin on himself and friends. Shulgin was interested in the psychoactive potential of many different substances, and tested many drugs similar to MDMA.

Shulgin reported analogues without psychoactive effects, regarding them as dead-ends. For Piggott, however, these are the properties he is seeking because cancer-fighting drugs that also induce euphoria or cause hallucinations would be temptations for abuse.

Cancer Cells Respond to Tag Team
Cell receptors associated with cancer respond differently to a combination of antibodies than they do to each antibody on its own, Swinburne University biophysicists have found.

Mutations affecting epidermal growth factor cell receptors have been implicated in some cancers. Instead of making the cell respond to its environment, the receptors trigger uncontrollable growth.

A/Prof Andrew Clayton tagged the receptors on cancerous cells with green fluorescent protein from jellyfish. The cells were then exposed to two antibodies. Neither antibody on its own produced a visible change in receptor behaviour. However, when both antibodies were tried at once the receptors clustered together.

“By looking at the mutated receptors on a molecular level, we were able to determine that this clustering reaction is a synergistic effect of the combination of antibodies,” Clayton says.

Antibody treatments are already used against some cancers, although Clayton says there is dispute as to how they work. “Either the view is that they flag the presence of a foreign body for an immune system response or they directly affect receptor functioning.”

Clayton says there is some evidence that receptor clustering prevents cells from recycling receptors that have become internalised, slowing the growth of cancerous cells. Certain chemotherapies are also known to work better in combination than individually, although Clayton says he is not sure if there is a connection.

The research was published in Global Medical Discovery.

Gunshot Residue Test
The mythical world of forensic wonders portrayed on CSI and Bones has come a little closer to reality with the suggestion of a way that barium can be detected in gunshot residues.

Gunshot primers use lead, antimony and barium, so the detection of all three elements indicates the presence of gunshot residue.

“There is no reliable and highly accurate on-site method for barium detection,” explains Dr Magdalena Wajrak of Edith Cowan University’s School of Natural Sciences. “Many other industries, such as oil and gas, use barium compounds and need to constantly monitor barium concentrations in their waste before releasing it into the environment.

“Currently, gunshot residues are collected using special adhesive sampling discs of various surfaces around crime scenes, which must then be sent to be analysed qualitatively by a scanning electron microscope,” Wajrak says. “This process is expensive, takes considerable time, requires trained chemists and may require additional samples to be collected later.”

Wajrak has suggested using anodic stripping voltammetry, a technique used to detect very small amounts of metal in liquid samples. “Each metal or semi-metal has a different stripping potential, and that’s how we can identify what metals are present in a particular sample,” she says.

While barium represents a particularly tough case, requiring particularly negative voltages to deposit barium ions on an electrode, Wajrak has been able to detect its presence in 10 ppb solutions. She is planning to improve the sensitivity further before experimenting in the field.

Final confirmation of gunshot residue will still require the use of scanning electron microscopes (SEMs) to detect characteristic changes to the morphology of particles. However, a good on-site test would reduce the number of samples that police collect, in the process slashing the expensive pressure on the SEM.

However, the idea of determining the make of bullet from the residue will remain a television scriptwriter’s fantasy.

Plant Productivity Exceeds Expectations
The plants and algae of the planet may produce at least 25% more living material than models have previously suggested. In the process they draw more carbon dioxide from the atmosphere. Unfortunately, a similarly larger amount is being released through decay.

Dr Lisa Welp of the Scripps Institute, California, who was lead author of a Nature paper, says: “It’s difficult to measure the rate of photosynthesis for forests, let alone the entire globe. For a single leaf it’s straightforward: you just put it in an instrument chamber and measure the CO2 decreasing in the chamber air.”

Past models of global primary production have extrapolated from measurements conducted on different kinds of leaves. Welp’s co-author, Dr Colin Allison of CSIRO Marine and Atmospheric Research, says that “uncertainties in these models propagated upwards”.

Welp and Allison were part of an international team that approached the problem in a different way by tracking changes in the oxygen isotopes incorporated in carbon dioxide molecules. The isotopic ratios change when carbon dioxide enters a plant and interacts with water in the leaves.

The team used 30 years of atmospheric samples from Cape Grim (Tasmania), Mauna Loa (Hawaii) and the South Pole, along with more recently established facilities, to track the changes induced by El Niño events. They observed a series of waves of oxygen-18 isotopes starting in the tropics and spreading towards the poles.

The speed of these waves gave the team a way of estimating how quickly carbon dioxide is cycled through the biosphere. “Our analysis suggests that current estimates of global primary production are too low, and the refinements we propose represent a new benchmark for models to simulate carbon cycling through plants,” Allison says.

Previous estimates have suggested that plants absorb and release 120 Gt of carbon per year, but this paper suggests the figure is actually 25–45% higher.

The Federal Opposition’s environment spokesperson, Greg Hunt, seized on the research, claiming it vindicates the policy of paying farmers to store more carbon in their soil.

However, Hunt was contradicting a commentary published in the same edition of Nature in which Dr Matthias Cuntz of the The Helmholtz Centre for Environmental Research in Germany concluded the opposite. According to Cuntz, the results indicate that trees are less efficient at sequestering carbon than previously thought, suggesting it will be much harder to remove carbon dioxide from the atmosphere on a long-term basis using techniques such as soil storage.

New Life for Tired Tyres
Used tyres are one of the most problematic forms of waste, but Deakin University researchers believe they may have a solution with a recycling method they expect will prove cost-effective.

One billion tyres are discarded each year, 20 million of them in Australia. Few are recycled as the current processes are energy-intensive, rely on damaging chemicals and produce a single product that is only suitable for low-value uses.

“Tyres simply dumped or placed in landfill are known to leach harmful chemicals into the environment, cause fires and provide a perfect breeding ground for pests like mosquitoes and rats,” says Mr Chris Skourtis of the Institute for Technology Research and Innovation.

Skourtis is part of a team that has demonstrated the viability of their alternative using a small-scale facility on campus. “First, the tyres are segmented in a way that allows for each part to be treated differently, which eliminates impurities and results in a higher quality end product,” Skourtis says. “For example, the steel reinforcement in the tyre is separated without fragmenting, which is not common in current tyre recycling.”

After this the rubber is devulcanised using a combination of heat and mechanical pressure. Rubber powders of varying quality are produced from different parts of the tyre.

“We have also developed a way of using ozone gas to activate the rubber powder, which makes it more compatible with other materials,” says Skourtis. “This extends the usability of the powder for producing a wider range of rubber and plastic products than currently possible.”

Some of the powders can be used for manufacturing new tyres, while others are suited to lower value uses such as insulation materials and asphalt additives.

Industry partner VR TEK Global is in negotiation to establish a commercial facility, and Skourtis expects this to happen in mid-2012.

Fish Biomass Measures Reef Health
Managers of coral reefs can measure the health of their reef through the total biomass of fish per hectare, according to a study published in the Proceedings of the National Academy of Sciences. As the weight of fish falls, a series of eight markers are observed that indicate declining reef health. As each of these is crossed, reef restoration becomes harder.

“Fishermen and scientists have long wondered how many fish can be taken off a reef before it collapses,” says Dr Nick Graham of the ARC Centre of Excellence for Coral Reef Studies. “The consequences of overfishing can be severe to the ecosystem and may take decades to recover, but hundreds of millions of people depend on reefs for food and livelihoods, so banning fishing altogether isn’t an option in many nations.”

The study was done in the Indian Ocean, and while Graham believes it will prove applicable to the Pacific he says this needs to be confirmed.

Healthy reefs studied had around 1000–1500 kg of fish per hectare. Warning signs began when fishing pressure reduced the biomass below 1000 kg. “For example, you see patches of weeds replacing coral, you see more sea urchins devouring the coral, you see a general decline in the species richness on the reef, and you see less coral cover,” Graham says.

When fished to maximum sustainable yields, the fish biomass fell to 300–600 kg/ha. Below 300 kg/ha lie five thresholds, ending with total ecosystem collapse.

“If a chronic stress like fishing is gradually degrading biomass it is more likely that a pulse event such as coral bleaching will tip the system into another state such as a macroalgae-dominated environment,” Graham says. However, the team acknowledged that fishing will continue because millions of people depend on fish for their protein or livelihood.

“So we also assessed how well different reef management schemes did at maintaining reefs within or above this sustainability window,” says Dr Joshua Cinner of the ARC CoE. Although no-take zones were the most effective reef protection, Cinner says that “a key finding from our study was that even easily enforceable regulations that restrict gear or the types of species that can be caught helped maintain biomass”.

Graham notes that certain species, such as herbivorous fish, may play particularly important roles in reef management (AS, May 2006, p.11), but says the team found that “total biomass was tightly correlated with the biomass of herbivorous fish and is easier to measure”.

Sandy Soil Solution
A cheap and simple soil additive designed to help plants survive the drought in their first year has proven effective at combating dieback, the disease caused by the fungus-like Phytophthora cinnamomi.

Perth’s sandy soils do not hold water well, making it difficult for newly grown plants to survive drought. “Our target is to modify the top 100 mm of sand into a sandy loam to increase its water-holding capacity and break water repellence,” says Mr Tom Long of the WA Water Corporation.

Long led a team that combined solid waste from water treatment plants with Cockburn builder’s lime in a two-to-one ratio. The lime converts the biosolids’ nitrogen to ammonia, while the phosphorus becomes calcium phosphate. The combination is mixed with 1.5 times its weight in clay to become Lime-amended BioClay (LaBC).

At 50 t/ha, the LaBC releases a year’s supply of nitrogen and 7 years of slow-release phosphorus. It also holds onto enough water to get many plants through a dry summer. Long says it is possible to stock seven times as many sheep on Bassendean sand that has been treated with LaBC than similar soils that have not.

Perth’s soils are also highly acidic, and the LaBC returns them to neutrality. Phytophthora prefers acidic soils, so the Water Corporation had A/Prof Elaine Davison of Curtin University tested how LaBC affected dieback. Not only did it stop the spread of the mould, but existing infections were killed within 6 days.

The combination of sandy and acidic soils is common in the south-west of Western Australia, but Long says that other coastal regions of Australia also have soil types that are likely to benefit from LaBC.

New Frogs Found
Two new species of frogs have been discovered inhabiting rocky outcrops in the rainforest of Cape York.

“It is exciting that in this day and age you can still go out in a fairly well explored country like Australia and find frogs totally new to science,” says Dr Conrad Hoskin, who is now at James Cook University but was at the Australian National University when he made the discovery.

The frogs spend the dry season deep within the boulders, coming to the surface at night after rain. “To explore these remote areas for frogs, we had to fly in during the wet season and hike through swamps to get to the boulder fields,” Hoskin says.

Similar boulder patches further south are also inhabited by frogs, leading Hoskin and Kieran Aland of the Queensland Museum to hope that they would find inhabitants in the areas they were searching. However, Hoskin says that “these piles each have their own species, and they’re very different from the ones further south”.

The frogs have been named the kutini boulder-frog (Cophixalus kulakula) and golden-capped boulder-frog (Cophixalus pakayakulangun), with the names based on Kuuku Ya’u words following discussion with local indigenous custodians.

“They are adapted to their rocky world in having long arms, long slender fingers and big triangular finger pads,” Hoskin says. “These features enable them to climb amongst the labyrinth of rocks in which they live, and they only occur in the rocks and never in the surrounding forest.”

Despite the small size of their territory, both species are quite common, feeding on ants and beetles in an environment that supports few other vertebrate species.

Secret of the Superbug
Clostridium difficile has become one of the most dangerous antibiotic-resistant causes of disease in hospitals worldwide. Now researchers from Monash University’s School of Biomedical Sciences have revealed part of what differentiates the deadly strain from milder versions.

C. difficile is normally kept under control by beneficial bacteria in the gut. However, the widespread use of broad spectrum anti­biotics has created plenty of environments where antibiotic-resistant versions can flourish unchecked. What is particularly problematic is that the antibiotic-resistant strain is also more virulent, causing chronic diarrhoea rather than the milder forms created more often by other strains.

“We’ve found that particularly dangerous strains of C. difficile are produced when a mutation effectively wipes out an inbuilt disease regulator called anti-sigma factor TcdC. Not only are these strains hypervirulent, they are resistant to broad spectrum antibiotics, making them difficult to treat,” says team leader Dr Dena Lyras.

But the absence of anti-sigma factor TcdC is not the whole story for superbug emergence. “There are so many differences between the strains,” Lyras says. “The superbug produces better spores, which are harder for hospitals to kill.”

The absence of a disease regulator leads the bacteria to produce more toxins, and to produce them earlier. Overproduction of toxins can kill the host more quickly than would be in the bacteria’s best interests, but in the current environment this is a small drawback compared with the benefits of antibiotic resistance.

C. difficile is not as well-known in Australia as golden staph. While Lyras acknowledges this may have something to do with its less catchy name, she says it has been “a low-lying problem that no one talks about that much”. However, major outbreaks in the UK and Canada have put C. difficile on the public agenda there, with hospitals becoming breeding grounds as spores produced in one antibiotic-treated patient spread to others.

Lyras says that UK hospitals have made substantial progress in controlling C. difficile’s spread by changing procedures. There is also work towards a vaccine.

“We know that if you can counteract the toxins in the gut, people don’t get sick,” she says. “New antibiotics also help, but they are not the best solution because this is an antibiotic problem. Anything that disrupts the normal gut microbes gives it an opportunity.”

Frog Overcomes Chytrid
The survival of the armoured mist frog, which was thought to have been wiped out by the chytrid fungus, offers hope for other amphibian species, according to scientists at James Cook University.

The frog was rediscovered in 2008 after being unsighted for 17 years. Now Dr Robert Puschendorf, who made the discovery as a PhD student, is part of a team explaining how the frog has overcome the fungus.

“We have found that this surviving group of armoured mist frogs and another species, the waterfall frog, are not only infected with the disease but they are thriving,” Puschendorf says. “The big difference was that these frogs were not in their normal environment of the wet, cooler rainforests of the tropics. They were living in a drier area which, while near the rainforest, had lower rainfall and less canopy cover.”

It is thought the frogs control the fungus by warming themselves in direct sunlight, raising the possibility that other species may be doing the same outside their core range.

Fast-Growing Prawn
A freshwater prawn that grows 25% faster could do for Mekong Delta aquaculture what the green revolution did for Indian wheat farming.

Prof Peter Mather of Queensland University of Technology Biogeosciences said: “Freshwater prawn aquaculture is a huge industry in south-east Asia worth more than $1 billion per year. It’s very important in the Mekong Delta because it provides livelihoods for many small farmers and freshwater fish is the main source of affordable animal protein available.”

Damage to river systems and the demands of growing populations have devastated wild stocks, making aquaculture even more important.

With funding from the Vietnamese Government, Mather selectively bred three varieties of prawn from the area, resulting in a fast-growing prawn that will allow farmers to slash the production cycle. Investigation of the genetic basis for the rapid growth may enable even more desirable characteristics in future, or the production of similarly speedy marine species of crustacean.

Dust Cloud Had a Silver Lining
The September 2009 dust cloud that covered eastern Australia in an orange haze actually cleaned Brisbane’s air, sweeping the ultrafine particles that can cause lung disease.

Dr Rohan Jauaratne of Queensland University of Technology attributes the change to the process of polydisperse coagulation, where diesel emissions and similar tiny particles diffuse on the surface of larger ones. “We have seen this happen in the laboratory but never in an environment like this, given the very specific conditions,” Jayaratne says.

During the storm’s peak, dust concentrations were 120 times normal levels. “One of the reasons vehicle emissions are so scary is that the ultrafine particles are able to penetrate deeper into the lungs, in the alveoli, whereas larger particles such as dust tend to get trapped in the upper respiratory system. Asthma is often caused by larger particles, but the finer particles are associated with long-term health issues such as cardiovascular mortality.”

Prostate Risky Genes
Segments of the human genome associated with an increased risk of prostate cancer have been identified. Genetic variations across seven segments put men at greater risk, particularly in combination.

“Our study found that the 1% of men at highest risk are about five times more likely than the average man to have prostate cancer, giving them a nearly one-in-two chance of developing the disease,” says Dr Amanda Spurdle of the Queensland Institute of Medical Research.

Spurdle says that previous work had identified the pieces of DNA most likely to be involved, but by clarifying the relationship the QIMR team has opened the way to better screening and possibly treatment. The findings were published in Nature Genetics.

Eat Your Greens
Broccoli, cauliflower and Brussels sprouts have had their healthy reputation confirmed, with evidence for a protective effect against colorectal cancer (CRC) published in the Journal of the American Dietetic Association.

“Fruits and vegetables have been examined extensively in nutritional research in relation to CRC, however, their protective effect has been subject to debate, possibly because of different effects on different subsites of the large bowel,” said Prof Lin Fritschi of the West Australian Institute of Medical Research.

Rather than treating the whole bowel as one, Fritschi distinguished between cancers of the distal and proximal colon and the rectum. Fruit (particularly apples) and vegetables proved beneficial for the distal colon but fruit juice increased the risk of rectal cancer. Brassica vegetable intake, but not total vegetable intake, was associated with a lower risk of proximal cancer.

Fritschi has previously demonstrated that folate consumption protects people with a raised genetic risk for cancers of the proximal colon.

Ewe Smell Familiar
Sheep have good memories for smell, and can use this to learn which individuals in their flock they should avoid.

For the first two hours after birth ewes find the odour of amniotic fluid very attractive. This imprints a memory of the smell of their offspring in their brain, and they will not allow other lambs to drink from their udders. Lambs, on the other hand, recognise their mothers based on the smell of colostrum produced for 48 hours after birth.

If bonds formed in this way are not allowed to develop, the ewes will abandon their young. However, Prof Graeme Martin of the University of Western Australia says that smell recognition extends to more complex tasks, despite the sheep’s reputation for stupidity. Sheep can remember the smell of every animal in the flock, and use this to position themselves in the hierarchy, avoiding challenging dominant animals.

Martin recommends that farmers make use of this new knowledge to increase lamb survival rates.

Context Matters in Mating
Male guppies decide whether to pursue a potential mate based not only on her attractiveness but also on how many other females they have recently encountered.

Male guppies are more attracted to larger females, and when housed with several potential mates paid attention only to the larger ones.

“When males have recently encountered few females – what you might call in the dating game a ‘dry spell’ – they expend significantly more effort in courting new females when they do meet up,” says Dr Alex Jordon of the University of NSW. This included paying attention to those they would have ignored when alternatives existed.

While the findings may seem obvious, Jordan says the research published in Evolution “reveals the sophisticated process that determines mating decisions, and shows a very strong effect of the social environment in the evolution of reproductive behaviour generally”.

More Evidence that Air Pollution Is Bad for Pregnancies
Babies born to women living close to traffic pollution are born an average of 58 grams lighter than those without such exposure, according to a study in the Australian and New Zealand Journal of Public Health.

Lead author A/Prof Gavin Pereira of the Telethon Institute for Child Health Research says: “International studies have found some associations, but this is the first time we have seen a specific link between normal suburban traffic pollution and its effect on the foetal growth”.

The findings add support to recent research indicating that exposure to traffic is correlated with earlier births (AS, September 2011, p.5).

Dot The Wasp
Technology used to recover stolen goods has been put to use tracking wasps. PhD student Mr Michael Whitehead is investigating the way the parasitoid thynnine wasp fertilises orchids.

“Bee tags were previously used to keep track of small animals, but they were too big in this case, and the electronic devices we could find weren’t going to work,” Whitehead explains. “So my brother and I came up with the idea to test out microdots as a tracking system.”

Microdots are 0.5 mm across and carry a personalised code that is usually used to identify the owner of valuable materials. However, Whitehead used nail varnish to glue them to the wasps’ backs. On recapture, 84% retained a legible microdot.

“When you’re able to individually mark the wasps you can get data on population size, movement and longevity,” Whitehead explains. He suggests that the technique might prove useful for preventing the poaching of rhino horns or elephant tusks.

The Wisdom of Solomon
Prof David Solomon and Prof Ezio Rizzardo have shared the 2011 Prime Minister’s Prize for Science. The pair invented new ways to control molecules, bringing them together in a structured way rather than relying on spontaneous processes.

Solomon achieved fame as the inventor of the polymer banknotes now used in Australia and many other countries. Rizzardo is still at CSIRO, where Solomon hired him as a postdoc in 1976, while Solomon is now at the University of Melbourne

The Science Minister’s Prize for Life Scientist of the Year went to Dr Min Chen of the University of Sydney for her discovery of the first new form of chlorophyll discovered in 67 years in cyanobacteria from Shark Bay.