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By Stephen Luntz

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Malaria Vaccine Target Confirmed

The importance of the protein PfEMP1 in the development of immunity to malaria has been demonstrated, marking a step towards a desperately needed vaccine.

Malaria infects human red blood cells and produces a range of proteins while it grows and multiplies within red blood cells. “People have long suspected PfEMP1 is an important protein in malaria, but increasingly the research community has identified a bunch of others, and the question is which are important,” says Prof James Beeson of the Burnet Institute.

Along with colleagues in Australia and Kenya, Beeson reported in the Journal of Clinical Investigation that people with immunity to the malaria parasite Plasmodium falciparum have antibodies that effectively target PfEMP1. On the other hand, the same protection against the disease is not achieved when the immune system targets other antigens.

Other species that cause malaria do not produce the PfEMP1 protein, but with P. falciparum representing three-quarters of the global disease burden of malaria, a vaccine that stimulates the immune system against the protein would represent a transformative step.

Beeson says the issue of why some people develop antibodies to PfEMP1, while others do not, is a complex one. “We know that the more infections people have, if they don’t die, the higher the chance is of becoming immune. You get higher and higher levels of antibodies until you reach a level where you are protected.

“There may also be some luck; sometimes people produce antibodies that are effective and sometimes they do not,” Beeson says. “There are also genetic factors that mean some people produce antibodies that are effective and others do not.

“Immunity against malaria takes a long time to develop naturally, so the aim of a vaccine is to short-circuit that and target a handful of key proteins so that we get a really good response over three, or hopefully two, vaccinations,” Beeson says.

“This finding should invigorate research efforts into how we can target this protein, rather than being diverted onto others. We also now know that PfEMP1 is naturally immunogenic.”

Unfortunately PfEMP1 comes in multiple forms, enabling it to evade the immune system. Consequently any vaccine will either need to target a stable component or involve multiple variants of the protein.

Nanomaterial for Hydrogen Storage

A major step has been taken towards the reversible storage of hydrogen that, if made practical, could transform the energy sector.

Hydrogen looks in some ways like the perfect form of energy storage. There is an almost infinite supply of it from water, and it burns free of pollution. However, storing the hydrogen itself presents many problems, with the gas likely to leak and notoriously flammable in an accident.

Dr Kondo-Francois Aguey-Zinsou from the University of NSW School of Chemical Engineering says his team achieved some success in using nanoparticles of magnesium to store hydrogen, and decided to explore nanostructures of sodium borohydride, a chemical known to store high densities of hydrogen.

The obstacles they faced looked intimidating. “No one has ever tried to synthesise these particles at the nanoscale because they thought it was too difficult and couldn’t be done,” says Aguey-Zinsou. To make matters worse, borohydrides were thought to be a one-off storage solution that was unable to reabsorb hydrogen once it had been released.

However, Aguey-Zinsou has announced in ACS Nano the production of nanoparticles of sodium borohydride encased in nickel shells that maintain the nanostructure when temperatures rise high enough to produce melting. “By controlling the size and architecture of these structures we can tune their properties and make them reversible. This means they can release and reabsorb hydrogen,” Aguey-Zinsou says.

Nanomaterials have large surface areas for their volume, which means that while bulk materials might take a day to saturate with hydrogen, Aguey-Zinsou’s product takes an hour. Absorption takes place at 40 bars of pressure, while high temperatures release the hydrogen for burning.

“Changing the size of the particles changes the bond strength,” says Aguey-Zinsou, “but we didn’t know which way it would go. By tuning the bond strength we have been able to get the hydrogen released at 350°C, but we believe 100°C is required for use in vehicles.”

Provided the release temperature can be reduced, sodium borohydride looks like a highly suitable storage material. “At 8–10% density a petrol tank of hydrogen would allow a car to drive 500–600 km without refuelling,” Aguey-Zinsou says.

Better yet, he says there is no problem with leakage. “Unlike batteries you could fill a tank with hydrogen produced from solar panels in summer and it would all still be there in winter.”

Jellyfish Everywhere

A reported rise in jellyfish blooms has caused considerable consternation in recent years. Prof Carlos Duarte proposes that the cause lies not in overfishing or climate change but in the expansion of hard marine structures.

Some dispute remains over whether jellyfish are actually becoming more common or if their populations are simply shifting (AS, April 2012, p.15). However, Duarte says that attempts to explain observations have focused on what happens during the mature swimming stage.

Before this is reached, however, jellyfish have a polyp phase in which they “settle on hard substrates in dark environments, such as the underside of rocks and stones”. Even macroalgae or seagrasses can play host to the jellyfish, but it seems they like human structures better still.

Duarte, who is Director of the Oceans Institute at the University of Western Australia, looked under docks, piers, pontoons and artificial reefs from Japan to Slovenia and found that “jellyfish polyps existed on the underside of such artificial structures at densities of more than 10,000 individuals per square metre, and sometimes up to 100,000 per square metre”.

“In many coastal areas dominated by sandy or muddy sediments, such hard substrates are scarce and, where present, are already colonised by other organisms,” Duarte says. Prior to the expansion of shipping facilities, “the substrate available for jellyfish settlement may have been a bottleneck in the abundance of polyps and, hence, the subsequent abundance of jellyfish”.

Duarte published his work in Frontiers in Ecology and the Environment. “Like most invertebrate larvae, the polyps use chemical clues to settle on habitats. This mechanism is similar to that of coral polyps, which are also cnidaria,” he says.

During the larval phase the main predators are nudibranches, but these require more oxygen than the polyps. Nutrient run-off creates oxygen-depleted areas of the ocean, providing a safe haven for the polyps.

Since jellyfish blooms can affect tourism, cause considerable damage to aquaculture and shut down power and desalination plants, Duarte says: “We need to design surfaces that deter polyps from settling while encouraging other, benign organisms to settle and occupy the habitat otherwise available for polyps. And we need to create healthy port environments where organisms other than polyps can settle and thrive and where polyp predators are also healthy.”

Insufficient Mitochondrial Fission in Alzheimer’s

The Queensland Brain Institute (QBI), in collaboration with Harvard University, has fitted another piece into the Alzheimer’s disease puzzle by revealing the involvement of irregularly long mitochondria.

Mitochondria are the prime generators of adenosine triphosphate, which cells use as their source of energy. Under normal circumstances the mitochondria within cells undergo a regular and tightly controlled process of fusion and fission. However, Alzheimer’s disease interferes with the fission process, leaving excessively long and inefficient mitochondria in neurons. This may be a contributing factor in the disease’s devastating effects.

“All cells rely on mitochondria for energy metabolism, and neurons in particular, so controlling the length of these subcellular structures is very important for brain function,” says Prof Jürgen Götz of the QBI Centre for Ageing Dementia Research.

The formation of tangles of tau protein within neurons is one of the definitive signs of Alzheimer’s disease. In the journal Neuron, Götz has reported that as tau starts to pathologically accumulate it causes an increase in actin levels within cells.

Actin then traps a protein called DRP1. This trapping prevents DRP1 from being localised in the outer mitochondrial membrane, where it would otherwise induce mitochondrial fission.

“Treatments currently available for these diseases have at most modest effects, in part due to our limited understanding of how Alzheimer’s disease starts and progresses,” Götz says.

Studies in fruit flies and mice have indicated that genetic and drug interventions that bolster mitochondrial fission can reverse the negative effects associated with the tau protein, offering hope for better treatments.

More South Pacific Climate Disruption

Debate continues over whether global warming will lead to more frequent extreme El Niño cycles, but the conditions that Australians and Pacific islanders associate with these events are set to increase anyway, according to a CSIRO report.

In a paper in Nature, Wealth From Oceans Flagship oceanographer Dr Wenju Cai reports that the majority of climate models predict an increase in extreme El Niño events over the rest of this century, but some models disagree. However, the models are unanimous in predicting more frequent large swings in the South Pacific rain band.

When the rain band moves to the north-east, Vanuatu, Samoa and north-eastern Australia suffer drastic falls in summer rain, leading to droughts and fires. “During extreme El Niño events, such as 1982–83 and 1997–98, the band moved northward by up to 1000 km. The shift brings more severe extremes, including cyclones to regions such as French Polynesia that are not accustomed to such events,” Cai says.

While shifts in the rain band are normally associated with El Niño, Cai says this is not the only factor causing the movement. “There have been three really large swings to the north-east in the rain band since 1979,” Cai says. “In 1982–83 and 1997–1998 the swing was driven by the strongest El Niños in the last century. However, 1991–92 was not a particularly strong El Niño, yet there was a huge shift in the rain band.”

Such movements in the absence of a strong El Niño look set to become more common. “The rain band follows the temperature closely, and all the models show that the equatorial region of the Pacific will warm more quickly than surrounding areas. This is what happened in 1991–92 with the equatorial region warming fast.”

Go South, Young Coral

Reef-building corals have been found in waters where they have never been observed previously, in what is considered yet another sign of global warming.

“Over the last 10 years researchers have observed clear increases in the number of tropical reef fish species appearing along the NSW coastline. We’re motivated by a growing number of corals and other tropical organisms being spotted, some as far south as the Sydney area,” says Dr Joshua Madin of Macquarie University.

Madin leads a team studying the southward expansion of corals responding to the 0.5°C warming of NSW waters over the past 50 years. This small change has allowed many species to survive in locations that were previously too cold for them. “So far we have not observed any newly formed reefs – that is, coral growing on dead coral – but we see coral growing on rocks,” Madin says.

A survey around the Solitary Islands off Coffs Harbour revealed 93 species of reef-building corals, four of which are easy to identify but have never been recorded in the area before. “The area was extensively surveyed in the 1980s so we are pretty sure these are new,” Madin says.

South of the Solitary Islands the number of reef-building species drops sharply, making the area a research target. Madin says that the variation in bio­diversity is more gradual between the islands and the southern end of the Great Barrier Reef.

Madin is collaborating with Japanese researchers tracking the northward movement of eastern Asian coral species. He has two warnings for those who see the appearance of southern corals as a substitute for losses on the Great Barrier Reef.

“The Japanese team have found species move at different rates, and while some can keep up with shifts in water temperature, more cannot,” Madin says. “The continental shelf is very broad where the Great Barrier Reef is. Further south it is much narrower, so we could not have something so amazing.”

Team members are investigating the presence of reef fish and crustaceans, as well as trying to determine what ecosystems the corals are displacing. Divers who observe unexpected species off the coast of NSW are invited to submit reports at http://acropora.bio.mq.edu.au/resources/observations/

Ciguatera Poisoning Is Rising

Ciguatera poisoning, a product of eating fish that have fed on certain microscopic algae, has risen by 60% in Pacific Island states during the period 1973–2008, a paper in PloS Neglected Tropical Diseases reports.

The algae contain toxins that bio-accumulate in the food chain so that large carnivorous fish are particularly unsafe to eat. Lead author Mr Mark Skinner of the University of Queensland’s National Research Centre for Environmental Toxicology says that little is known about how the toxins affect fish, but there have been reports of turtles dying as a result of consuming the algae, and even crustaceans may be vulnerable.

“Ciguatera occurs in up to 400 different fish species – and there is no way of knowing if a particular fish has the poison. A detection test was previously developed, but has proven unreliable, and any future test would likely be unaffordable to most Pacific Islanders,” says Skinner.

“While fatalities may be rare, ciguatera poisoning makes people dreadfully ill, so much so they often cannot earn a living for weeks or even months. So it has big social and economic implications,” says co-author Mr Tom Brewer of the Centre of Excellence for Coral Reef Studies. Symptoms include intense lethargy, severe cardiovascular symptoms and dehydration.

There are many contributing factors to the rise, including the replacement of coral reefs with seaweed habitats, transmission of the more toxic species of algae in ballast water and global warming.

Brewer notes that poisoning is much more common when sea surface temperatures exceed 28ºC, something increasingly common in island lagoons as global warming takes hold. Skinner adds that many Pacific Islanders believe nuclear testing played a part, with the worst outbreaks near French naval bases, but this is still considered a left-field hypothesis.

Those unwilling to act to prevent entire nations going under water are unlikely to be spurred to tackle climate change by a rate of 2000 annual poisonings per 100,000 people, but Skinner says the most important thing that can be done is to cut the flow of pollutants from the land. “Tahiti went downhill in the 1970s and has not got back to good conditions,” he says. “They have not dealt with nutrients coming off land.

“The top priority is catchment management, which also gives a chance for coral to come back.”

Lyrebirds Make Great Liars

Lyrebirds are such great mimics they can even fool the species they are copying, according to research published in Animal

Behaviour. Acoustic analysis of the lyrebird’s imitation shows it contains some differences from the original, but nevertheless reveals a remarkable and unexplained skill.

“To test the accuracy of the lyrebird’s mimicry, we performed an acoustic analysis comparing the real songs of the grey shrike-thrush with the lyrebird’s mimicked version,” says Anastasia Dalziell, a PhD student at the Australian National University’s Research School of Biology. “Grey shrike-thrushes sing a complex and beautiful song, but lyrebirds can accurately mimic them all the same.”

The lyrebirds were replicating the structure of the shrike-thrushes, but cut the song short by skipping repeated notes so they had time to imitate other species.

Male lyrebirds will imitate 20–25 different species during the mating season. It appears females are attracted to the capacity to copy as many species as possible, so the males do not want to dwell on any one species too long.

“We also wanted to ‘ask an expert’ how accurate lyrebird mimicry was,” Dalziell says, “so we played back recordings of lyrebird mimicry to the shrike-thrushes themselves. Surprisingly, shrike-thrushes approached the speaker broadcasting mimicked songs as well as the shrike-thrushes’ own song.”

When the shrike-thrush’s song was played as part of a typical lyrebird medley, the thrushes were better at working out that they were listening to a lyrebird than when they were played the imitation of the song on its own, but were still sometimes fooled.

Dalziell says some other bird species are sometimes fooled into approaching lyrebirds in the wild, leading to often amusing interactions. However, lyrebirds breed during the winter and most singing occurs at this time, when Dalziell says “all sensible bird species are doing winter things rather than breeding”. Consequently, opportunities for confusion are reduced.

As well as being great mimics, male lyrebirds clearly have excellent memories as they not only remember songs from a different season but from year to year if a particular species is absent.

Despite reports that lyrebirds have taken to imitating human sounds, Dalziell never witnessed this among her study group, even though their patch lies in an area commonly visited by tourists.

All of this leaves unanswered the big question: why do lyrebirds mimic others songs rather than making up their own? Dalzeill says that “lyrebirds experience strong sexual selection, and since the female raises the chick on her own she is not looking for a good father but for a good singer and dancer”. However, she admits being puzzled as to why female lyrebirds like a male who can imitate lots of other species calls.

Mimicry of other species’ mating behaviour has been used to devastating effect by invertebrate predators, but Dalzeill says there is only one unconfirmed report of similar behaviour among birds. Lyrebirds are not related to cuckoos (AS, June 2010, pp.8–9), so Dalziell says the behaviour is not an outgrowth of the cuckoo’s copying of its host’s calls.

Fungus Could Unblock Waterways

An Australian native fungus could be the solution to one of northern Australia’s most damaging invasive plants, and other weeds could be similarly vulnerable.

“A Northern Territory Landcare Officer, Colleen Westover, noticed some Parkinsonia trees were dying and sent me samples to see if I could find out what was causing their deaths,” says A/Prof Victor Galea of the University of Queensland’s School of Agriculture and Food Sciences.

Galea isolated 200 local fungi and identified three that are particularly effective in controlling Parkinsonia. “The fungi are found naturally throughout Australian soils, which means we have avoided biosecurity risks from importing new organisms into Australia from overseas,” Galea says.

The use of fungi as a bioherbicide is not new, but Galea has added a novel distribution method to the fact that his fungus is the first Australian native put to such service. “We have tested and refined a simple system with capsules containing millet that has been colonised by the fungus and is all packaged up and ready to go,” Galea says.

“We simply drill a hole in the tree trunk, insert the capsule and then seal the hole with silicone.”

Other bioherbicides are distributed on the wind or in sprays, but Galea says the relatively large size of Parkinsonia plants makes direct injection viable. “All you need is a cordless drill, a caulking gun and some capsules. Landcare groups could use it.”

Parkinsonia produce huge seed crops (AS, Jan/Feb 2007, p.11), but once the fungus is established it kills new plants nearby. Moreover, the fungus spreads about 1 metre per year, and can jump from the roots of one plant to another in the increasingly common Parkinsonia thickets.

Galea says it can take 100 generations for widespread resistance to emerge to a control treatment. This is a problem when fighting herbaceous weeds, which often have life cycles of 8–10 weeks. However, Parkinsonia has a lifespan of 15–20 years, so Galea is confident we will have plenty of time to develop fallback solutions.

Galea is identifying and testing similarly potent fungi against other species invading northern Australia, such as Mimosa and Athel pine.

In the meantime the prickly Acacia represents a particular challenge since, Galea says: “You take your life in your hands trying to get close enough to drill its stem”.

Things of Plastic and Wood

A composite material made from recycled plastic and sawdust may help to rebuild Christchurch, the city in which it was invented.

“New Zealand uses at least 200,000 tonnes of plastics a year and only 35,440 tonnes are recovered with the rest ending up in landfills,” says Prof Shusheng Pang, director of the University of Canterbury’s Wood Technology Research Centre.

“Wood in its original form swells when it gets wet and shrinks when it is dried,” says Pang. “If not properly designed and constructed, wood stability and durability can be a concern for wooden structures such as leaky houses. Currently wood is chemically treated for building purposes if high durability is required.”

While Pang is not the first to have the idea of combining wood scraps and plastic he says: “All other composites are made through injection and moulding. We are using a hot press and different processing technology for recycled plastics.”

Although Pang says a wide variety of plastics can be used, he adds: “Different types need different formulations so they must be sorted beforehand.” Both the plastics and the wood need to come in uniformly sized particles, but this should prove no obstacle as sawdust is widely available from mills around Christchurch.

Pang claims his product is “more stable and durable than original wood and stronger than original plastics”. Small prototypes have been produced, and the University is seeking an investor to establish large-scale production before Christchurch finishes the 5–7-year period anticipated for rebuilding the city after last year’s earthquakes.

Train Sounds Intelligent Warning

The largest trial in the world of an intelligent transport system has been conducted on Melbourne’s Frankston line, offering hope for an end to collisions between cars and trains.

Only one-third of the level crossings in Australia are equipped with booms and flashing lights, and the cost of outfitting the rest is considered prohibitive. Instead Prof Jugdutt Singh of La Trobe University’s Centre for Technology Infusion hopes to enable trains to trigger a warning in nearby cars.

Proposals are under consideration in the United States for all new cars to be fitted with dedicated short range communication (DSRC) technology. Ultimately the goal is to enable cars to communicate with each other to avoid collisions. Such a step is a long way off, but Singh is taking advantage of the technology to allow trains to send a signal to car drivers.

A night trial conducted between Highett and Cheltenham stations saw eight trains send signals warning of their presence to cars fitted with DSRC technology for a month. These triggered warning messages that were calibrated depending on how close to the train the car was, and whether it was heading towards, parallel to or away from the train line.

“At 500 metres or 1 km away an icon might pop up in the SatNav,” Singh says, “but if you are travelling towards the train it might take over the screen. If a collision is imminent it will make bells sound in the car and lights flash.”

The stretch of track was chosen for the complexity of the roads feeding into it, with some roads approaching crossings at angles.

Singh says there are many steps still required before the system can be used in practice, but the trials “exceeded expectations.” He adds: “Human factors are very important, and we have psychologists involved to try to ensure people don’t ignore the messages”.

The car stock takes a long time to turn over, but Singh says the DSRC is cheap to retrofit so it may become widespread fairly quickly, and may even be fitted to motorbikes.

Sound Solution for Pipes

The urgent task of restoring water supplies after natural disasters could be eased with a new method for detecting blockages and leaks being developed at the University of Canterbury in New Zealand.

Dr Pedro Lee is sending pressure signals through the water in a set of pipes and detecting the reflection caused by changes in conditions. “Both blockages and leaks can be detected, and their signal is basically opposite so you can tell them apart,” he says.

“Our project has particular relevance for the Canterbury region as its success can improve our response to future earthquakes as well as improve the efficiency of our water infrastructure,” Lee adds.

The pressure waves travel at the speed of sound in water (which is three times faster than in air). A particular virtue is that the tests work while the system is operating rather than requiring a complete shutdown, as is currently the case.

Aside from the application to disaster recovery Lee hopes his work will be useful for ageing infrastructure that is leaking as a consequence of normal wear and tear. He notes that almost one-quarter of the outbreaks of waterborne disease in the United States in recent years came from leaks in the water and sewage system, while pumping costs rise as a result of unlocated blockages.

“Under controlled circumstances we can detect very small leaks, but it all depends on the system you are applying it to,” Lee says. “In the real world there is lots of noise from things like people flushing their toilet or turning on the taps, and it depends on whether you are flooded by these things.”

He adds that some field testing has already been conducted, and hopes to have a “polished product” in 3 years.