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By Stephen Luntz

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Brain Stimulation Explained
A study of repetitive transcranial magnetic stimulation (rTMS) on mice has improved our understanding of a treatment already in clinical use but conducted with little comprehension of how it works.

A/Prof Jennifer Rodger of the University of Western Australia’s School of Animal Biology says the idea of using electricity to improve the brain’s function goes back to the ancient Romans, who put electric fish on themselves to cure headaches. The discovery that the brain operates electrically put the idea on a firmer basis.

rTMS avoids the excruciating pain associated with electroconvulsive shock therapy by having magnetic stimulation generate electrical impulses inside the brain so that the electric charge does not need to cross the skin. The electric currents are also much weaker.

Magnetic stimulation was first used to map the brain, with magnetic fields applied to certain areas that produce reactions in particular parts of the body.

Nevertheless, not much has been done in terms of animal experimentation, and since it is hard to examine the brains of people who have undergone rTMS immediately afterwards, an explanation of how it works remains elusive.

Rodger is the first to produce a magnetic coil scaled to a mouse brain rather than something suited to a much larger animal. She used a strain of mice with disorganised areas of the brain and other areas intact. After 2 weeks of daily rTMS for 10 minutes, adult mice exhibited a reordering of the defective parts of their brains.

Rodger says that “the normal connections stayed normal” and behavioural improvements were observed. For example, mice with defective visual systems showed improved reactions to moving objects.

Gene expression has been observed to change in humans who have experienced rTMS, and Rodger says similar changes were seen in the mice, validating the model.

Although rTMS has been used to treat depression, Parkinson’s disease, stroke and schizophrenia, Rodger says studies have been mixed, with some showing long-lasting benefits, others only short-term results, and some no improvement relative to a control group.

“Our results greatly increase our understanding of the specific cellular and molecular events that occur in the brain during rTMS therapy,” Rodger says. She hopes this will enable more consistently beneficial treatment.

Malaria Goes Bananas
An explanation has been found for how the malaria parasite bends the blood cells it inhabits into a banana-like shape prior to sexual reproduction, raising a possible new line of attack on the killer disease.

“In 1880 the banana or crescent shape of the malaria parasite was first seen in the blood of a patient,” says Dr Matthew Dixon of the University of Melbourne’s Department of Biochemistry and Molecular Biology. “Using a 3D microscope technique, we revealed that malaria uses a scaffold of special proteins.”

These proteins are used by the parasite to enter the blood cell, and again while in the mosquito’s midgut. “The fact that they are used at so many stages means they might be particularly good to target, but at this stage no vaccine has been designed against them,” Dixon says.

The banana shape is a necessary compromise for the parasite, allowing the blood cell it has infected to slip through narrow slits in the spleen. Without this change, the increased rigidity of infected cells would make them easy targets for the body’s immune system. Transformation into an even more elongated shape would place the blood cell under too much stress and cause it to rupture.

Once drawn into a mosquito’s digestive system, the parasite loses the blood cell and, depending on sex, turns into cells that resemble mammalian sperm or eggs.

Snails Feel the Heat
Climate change represents a threat to snails, but gardeners should not celebrate: the species in trouble live on rocky coastal outcrops rather than backyard vegetable gardens.

“A lot of current global warming research uses air temperature as a proxy for animal body temperature, so if it’s 31° at the beach they’d say all the animals at the beach are 31°, but that’s not the case,” says Coraline Chapperon, a Flinders University PhD student.

Chapperon used thermal imaging of the snails and their locations to reveal that the temperature of the rock on which a snail sits determines its body heat. “Even the same rock surface varies in temperature at a very small spatial scale at one time, which is more pertinent to the biology and ecology of intertidal animals than air temperature.”

Other research has indicated a maximum temperature at which Nerita atramentosa can survive. Chapperon says that this puts the snails of Marino Rocks, where she did her studies, close to the top of their “thermal tolerance window”. Southward migration is obviously slow, and Chapperon questions whether the South Australian snails will run out of places cool enough.

Chapperon found that the inhabited rocks can vary greatly in temperature over distances of just a few centimetres, providing the snails with survival options.

“Despite their limited physiological abilities, snails have certain behavioural qualities that help them cool down when it is warm, such as aggregating or moving underneath rocks,” Chapperon says. In close conjunction the snails can humidify the atmosphere, providing a small cooling effect. “But this is a relatively unknown area of research, and that’s why further studies are needed to see whether their ability to find refuge in cooler microhabitats could compensate for their lack of physiological ability.”

Snails may not be the most popular of creatures, but Chapperon says they are important to the food web, taking energy from primary producers and providing food for other species.

Potoroo Rescue Successful
A program to rescue the world’s rarest marsupial has met with success, with Gilbert’s potoroos taking to protected new territory in Western Australia.

The tiny fungus-eating marsupial was badly affected by the introduction of foxes and feral cats, and was once thought extinct. It survived as an accidental effect of efforts to preserve the heathland bird habitat around Two People’s Bay from urban encroachment from Albany and frequent fires. Without fire, the local ecosystem grew too dense for introduced predators, allowing a colony of 30–40 potoroos to survive.

Upon its discovery in 1994, ten potoroos were moved to Bald Island. These have now multiplied to the point where Dr Tony Friend of the Department of Environment and Conservation says they may have exceeded the island’s long-term carrying capacity. Consequently 21 have been moved to a fenced enclosure in Waychinicup National Park.

“The species is mostly fungivorous, and the south coast of WA provides enough rain in summer to get good truffle abundance all year round,” Friend says.

Little is known about the potoroo’s original range, and researchers were surprised to see them expanding into jarrah woodland as well as heathland similar to the environment around Two People’s Bay. “This data gives us more information to select other potential translocation sites,” Friend says.

Although the species have been through a population bottleneck, Friend considers the genetic health good enough to be sustainable as long as the population can be established at sufficient sites. He points to the Mauritius kestrel as an example of a species that has thrived as a result of proper breeding after it had diminished to a handful of individuals. “The lack of genetic diversity may mean it won’t be able to adapt to climate change, but so far we don’t see that happening.”

Alongside government funding, the breeding and translocation programs have received considerable support from the local community, with an action group donating more than $20,000 for trapping and monitoring equipment.

The potoroos were relocated in two batches, and the first proved a surprise. Radio transmitters found the original group keeping close together. “This challenges existing understandings, because often a lone male would just stick around a female, but this group is almost displaying herd behaviour,” Friend says. However, the second group spread out far more widely, and the original observations may have been coincidence.

Manorexia Worked Out
A sample of weightlifters in northern NSW gyms found that 10% have symptoms of muscle dysmorphia, which is sometimes referred to as reverse anorexia.

Those suffering from muscle dysmorphia are convinced that, no matter how muscular they are, their body is too small and weak. It is commonly associated with the use of illegal bodybuilding drugs and exercise that hinders recovery after serious injuries.

“At the moment, no reliable criteria exist for diagnosing muscle dysmorphia, so all we can say is that people have symptoms that suggest they are at risk,” says Southern Cross University PhD student Johanna Nieuwoudt. “My next task is to see if we can validate the criteria we are using.”

Nieuwoudt’s criteria include giving up important social activity in order to work out, avoiding situations that require exposing the body to others, and clinically significant levels of distress associated with a preoccupation with having an insufficiently muscular body.

Although Nieuwoudt says 8–10 questionnaires exist to identify possible cases of muscle dysmorphia, little is known about the condition, which was first proposed in 1993. In particular, she says that while there are some theories about causes, nothing is really known.

Nevertheless, the dangers are considerable, including damage to the kidneys and cardiovascular system, as well as musculoskeletal injuries from over-exercising.

Nieuwoudt stresses that her northern NSW sample should not be taken as a reliable measure of weightlifting populations nationwide, but notes that there may also be a hidden population of people who are deeply troubled by their sense of insufficient muscularity but do nothing about it, at least in public.

Nieuwoudt found that her criteria were particularly common among weightlifters with larger biceps and those who used supplements.

Global Warming Hotspot
An area to the east of Tasmania has been identified as one of a number of global warming hot spots caused by changes in ocean currents.

Dr Wenju Cai of CSIRO Wealth from Oceans has reported in Nature Climate Change that the warming planet is increasing the wind speed at latitudes of 45–55°, driving the South Pacific gyre further south at the same time as its strength is increasing. As a result, the warm waters of the East Australian Current are penetrating 350 km further south, raising temperatures in the area at more than double the global average.

“Detecting these changes has been hindered by limited observations, but with a combination of multi-national ocean watch systems and computer simulations we have been able to reconstruct an ocean history in which warming over the past century is two to three times faster than the global average ocean warming rate,” Cai says.

Cai expects the area to continue to warm faster than the global average, as high latitude wind speeds grow further. He notes that a large part of sea level rise is due to thermal expansion of the upper layers of the oceans, so the local sea level rise off Tasmania and New Zealand should exceed the global average.

“We expect changes in marine ecosystems, and these have been observed,” Cai says. “Fish species that are not supposed to be in Tasmanian waters have been seen. The NSW sea urchin is now eating kelp forests that provide shelter for many other species.” New Zealand is also experiencing accelerated warming compared with other parts of the globe.

Not all the changes are bad. Cai says the warmer waters could mitigate the reduced rainfall expected along Australia’s east coast as a result of other effects of global warming.

CSIRO is part of a project that will deploy ocean sensors moored to the sea floor in March 2013, giving a far more detailed picture of the changes to the East Australian Current. These will complement data from ARGO floats (AS, June 2010, p.4) and a glider that is carried at great depths by ocean currents.

The same pattern of extended warming has been observed at equivalent positions in every other ocean basin, indicating that every western oceanic current is strengthening. “Only global climate change could give a synchronised signal like that,” Cai says.

Protein Absorbs Body’s Shock
Cells in the body are protected against shocks by the molecular equivalent of a pogo stick, according to research published in the Proceedings of the National Academy of Sciences. A modified version of this may be put to use in artificial blood vessels.

The protein elastin enables expansion and contraction of elastic tissue. Without it, the body’s cells could not resume their shape after stretching or contraction, and essential functions such as breathing could not occur.

Prof Tony Weiss of the University of Sydney’s School of Molecular Bioscience has taken this knowledge a step further by identifying a long elastic spiral within the molecule that joins to something he says “looks like a foot”.

“This coupling region is able to expand and contract and therefore ameliorate the effects of external shocks on a cell,” Weiss says. “It performs the same function for humans at a molecular level as shock absorbers do in a car; we can enjoy a smooth ride because they keep the body of the car from being violently rattled by the movement of the wheels.”

Although elastin’s importance has been known for some time, Weiss says scientists lacked the right tools to get a clear picture of the molecule. His lab took a bottom-up approach, connecting together the pieces that make up the protein.

Elastin exists in many parts of the body, but Weiss says one of the greatest concentrations lies in the aorta, which needs to expand and contract in response to surges of blood.

“This part of the molecule is very susceptible to protease activity, but it is conserved amongst all mammals we have studied,” Weiss says. The conservation means there is little room to move evolutionarily when the protein comes under attack, so the body requires rapid repair mechanisms when elastin is damaged.

“We know that surrounding cells produce a trickle of tropoelastin when damage to elastin is detected,” Weiss says. Nevertheless, the extent to which elastin wears out as we age is visible in the changes to our skin.

Weiss has modified the spring component to produce an artificial version of elastin he says should be longer-lasting. “This finding will benefit our work on designing artificial blood vessels that use replicas of human elastin to repair and replace human blood vessels, with implications for the treatment of cardiovascular disease. In the future it may have applications in treating emphysema, which is caused by destruction to lung elastin.”

Hate Thy Neighbour
Ants can recognise members of a different colony they have encountered before. Moreover, they can transmit this knowledge to fellow colony members, although the process involved is still mysterious.

“It has been known that across lots of ant species there is a correlation between the distance between ants’ nests and the level of aggression of their encounters,” says Prof Mark Elgar of the University of Melbourne’s Department of Zoology.

A popular theory holds that neighbouring nests are more closely related, and ants recognise this, stimulating a more aggressive response.

Elgar tested the alternative idea that past encounters stimulate a reaction by placing weaver ant nests together in groups of three. Each day, ants from one nest would be introduced to the territory of another, while no such transfer was done with the third colony.

At the end of the trial, ants from each neighbouring nest were brought to the test nest, and those from the nest to which the ants had been habituated received a much stronger response.

“When two ants meet they will pat each other with their antennae and sometimes open their mandibles, which is interpreted as a threat. If they are from different colonies they will chase each other, bite legs and in some species spray each other with poison. In the most extreme case one will bite the other’s head off,” Elgar says. “We counted how many of these were displayed to measure the aggression of the encounter.

“When a colony was exposed to intruders from the same rival nest repeatedly, we saw the encounters were increasingly aggressive, suggesting that ants were passing on information about the frequency of interaction to their nestmates as well as information about their identity.”

Elgar is unsure how ants within a colony are taught to recognise the smell of neighbours they have never themselves encountered.

Elgar is also puzzled about why some species of ants are less aggressive towards their neighbours than more geographically distant species. “Nasty neighbours are easy to explain because an adjacent colony is a greater threat, but I can’t see the evolutionary benefit for the reverse,” he says.

Elgar says the work needs to be replicated in other species, but comparisons have already been drawn with football fans who are more hostile to their local opponents than those from a different city.

The work was published in Naturwissenshaften.

New Sea Snake a Roughie
A new species of sea snake has been located in the Gulf of Carpenteria, and is distinguished by its uniquely rough scales.

“Some sea snakes have patches of rough scales,” says its discoverer, A/Prof Bryan Fry of the University of Queensland’s School of Biological Sciences. “However, this one has much rougher scales and they are all over its body.”

Publishing in Zootaxa, Fry named the snake Hydrophis donaldii after his boat captain David Donald, and admits that the rough scales make it less hydrodynamic. “Given the selection pressure to be as smooth and slippery as possible, the scales must have important ecological roles,” he says. “We think it is because they live in rocky environments and the scales protect them against sharp rocks that would cut other snakes to pieces.

“Weipa really is one of the last sea snake ‘Serengetis’,” Fry says. “We can see over 200 sea snakes in a single night’s hunting, whereas sea snake populations have really crashed elsewhere through overfishing removing their prey and also the snakes drowning in trawling nets.” Fry adds that while the snakes may be thin enough to slip through gaps in the nets, the volume of catch in the nets frequently prevents them from escaping.

Fry surveyed as many environments as possible around Weipa rather than simply searching areas known for their rich fish populations. He credits Donald for knowing where the rocky outcrops were located so that H. donaldii could be discovered and its habitat confirmed at similar locations.

Like other species in Australian waters, H. donaldii is a true sea snake and not a krait (AS, September 2004, p.5), but Fry says it looks nothing like its genetically closest relative. The venom has yet to be analysed but Fry is excited, reasoning: “All venomous animals are bioresources and have provided sources of many life-saving medications, such as treatments for high blood pressure and diabetes”.

An AI Approach to GPS
Studies on rodent and insect navigation systems have inspired an alternative to GPS.

“At the moment you need three satellites in order to get a decent GPS signal, and even then it can take a minute or more to get a lock on your location,” says Dr Michael Milford of the Queensland University of Technology. Buildings and tunnels interfere with the signal.

Milford’s alternative is called Sequence Simultaneous Localisation and Mapping (SeqSLAM). It relies on recognising a location from an enormous database of images, such as Google’s Streetview. Expansion to new locations could occur through crowdsourcing, with users adding photos of places they have visited.

Many streets seem indistinguishable from each other, but this is where the “sequence” component comes in. Rather than comparing a single image, SeqSLAM looks at a series to find a location.

Checking every street on the planet might strain any system’s software, so Milford says SeqSLAM starts with the assumption that the user has not teleported from the last known location. “If after checking all the nearby streets it can’t find a match, it will look more widely and that might take longer.

“The core of the research is how to deal with change in an environment,” Milford says. “The research is based on a central algorithm that looks at a sequence of images, using a significant stretch of a street as a way of getting around construction work or even traffic.”

Milford says the system has no direct basis in the way rats or insects navigate, but was inspired by his research on how creatures with small brains and blurry vision find their way around. “As we develop more and more sophisticated navigation systems they depend on more and more maths and more powerful computers,” Milford says. “But no one’s actually stepped back and thought: ‘Do we actually need all this stuff?’”

Nanoparticles Raise Solar Efficiency
Swinburne University researchers have broken the record for the efficiency of plasmonic thin film solar cells. While converting 8.1% of sunlight to electricity leaves them well behind crystalline cells, the development opens the door to further improvements that could restore thin film’s advantage in the race to generate cheap power.

Thin film solar cells are much cheaper to produce than traditional panels as they use much less silicon. However, with efficiency rates less than half that of monocystalline cells, thin films have struggled to compete following a dramatic fall in the price of high-grade silicon. Some thin film manufacturers have closed as a result.

Nevertheless, silicon can’t keep getting cheaper forever, and many observers believe that thin films will again have their day in the sun – provided they can narrow the efficiency gap.

While some labs have produced thin films with substantially higher efficiency, Prof Min Gu of the Victoria–Suntech Advanced Solar Facility (VSASF) says that the best currently in mass production convert just 6% of the light that falls on them.

“We took cells off a production line and imbued them with gold nanoparticles,” Gu says. By chance, one of the manufacturing techniques the VSASF used produced nanoparticles that were bumpy rather than spherical.

The researchers realised this could be an advantage. While spherical nanoparticles only capture light of a wavelength that matches their radius, the different-sized lumps meant that many frequencies of light can be converted.

“Others have tried using different-sized nanoparticles,” Gu says, “but at any one spot you might have only one or two sizes. If you try to pack too many particles in you get shading.”

While Gu stresses that the traditional chemistry techniques used are cheap and “very scalable”, particularly compared with the electron beam lithography tried by others, the use of gold does not bode well for the cost of mass production. Consequently Gu says that the team has replicated the result with silver nanoparticles, and is now trying aluminium.