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By Stephen Luntz

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A New Form of Chlorophyll
The first new member in 60 years has been added to one of the most important families of organic molecules. “Chlorophyll-f” has the capacity to capture light of longer wavelengths than other forms of the vital molecule, opening up many questions as a result.

Plants, algae and some bacteria use chlorophyll to capture energy from sunlight and convert carbon dioxide into sugars and oxygen in the process. Despite being the basis for most life on Earth, chlorophylls are inefficient. They reflect light in the green part of the spectrum, producing the dominant colour in leaves, but in doing so miss out on the wavelengths at which sunlight is most intense.

Most plants convert sunlight at efficiencies of just 3–6%, with peaks at wavelengths depending on which chlorophyll molecule is used. Most species use either chlorophyll-a or chlorophyll-b, but chlorophyll-c and chlorophyll-d are known, along with unconfirmed reports of chlorophyll-e.

“Finding the new chlorophyll was totally unexpected – it was one of those serendipitous moments of scientific discovery,” says Dr Min Chen of the University of Sydney’s School of Biological Sciences. “I was actually looking for chlorophyll-d, which we knew could be found in cyanobacteria living in low light conditions. I thought stromatolites would be a good place to look, since the bacteria in the middle of the structures don’t get as much light as those on the edge.”

Chlorophyll-d has the capacity to collect light at wavelengths of almost 700 nm. Chen’s version collects even longer wavelength light at 706 nm. Since longer wavelength light has less energy, chlorophyll-f poses a conundrum: how is there enough energy in the light it absorbs to photosynthesise oxygen?

Less puzzling is the reason for the use of such low energy light. Longer wavelength light penetrates better to the middle of the stromatolites, so it represents most of the energy that bacteria at the centre would receive.

Intriguingly chlorophyll-f has the same mass and probably the same combination of atoms as chlorophyll-b, but with a different arrangement. So far Chen has been unable to determine which member of the stromatolite ecosystem produces chlorophyll-f, let alone how it operates.

Applications for chlorophyll-f are undoubtedly a long way off, but Chen says: “It will definitely give solar researchers the idea that they can modify their pigments so they accept a wider part of the spectrum”.

You Can Get It Pollinating Flowers
Australia’s native bees share with humans a preference for a warm drink on a cold morning but shift to a cold one when the day warms up, according to research published in PLoS One.

Like other insects, bees need to be warm to fly. When resting, their body temperature cools down, and they raise it by shivering or through certain biochemical reactions. Both mechanisms use energy.

However, Dr Melanie Norgate and Dr Adrian Dyer of Monash University’s School of Biological Sciences found that if bees choose nectar from warmer flowers, they can keep their temperature up without having to do any work.

“The bees perceived warmth as an important reward in addition to the nutritious nectar that they collect from flowers,” Dyer says. This finding confirms earlier work done on bumblebees, including by Dyer himself.

However, previous research could have simply reflected the fact that warmer substances are easier to smell. Norgate and Dyer took infrared images of bees leaving flowers, demonstrating the warmth benefit of a hot drink, and conducted the tests under a range of ambient temperatures. Once the air hit 34°C the bees preferred nectar at room temperature over warmer nectar. However, they never rejected nectar at the wrong temperature if it was all that was on offer.

“The study showed that just as a person might choose which type of drink to have depending on the weather, the bees also made a decision on their drink based on which flowers might offer nectar at the ideal temperature for the particular climatic conditions,” says Dyer.

Some flowers alter the temperature of their nectar using exothermic chemical reactions, but Norgate says this is rare. However, more subtle methods exist, including changing the colour of the flower to absorb or reflect more light, offering a shape that protects against breezes, and whether the flower is in sunlight or in shadow at that time of the day. Warmth can benefit flower growth as well as pollination.

This work was done in the lab, with temperatures raised artificially, but Norgate is keen to study how flowers and bees interact in the field if funding can be obtained.

So far there is no comparable research on other insects, but Norgate notes that related African bees fan their hives to keep them at 34°C, suggesting there is something universal in the preference for that temperature.

Biochar Gains Quantified
An international report on the potential for biochar to fight global warming has contradicted both those who dismiss the technology as irrelevant and others who see it as a panacea allowing unlimited pollution.

“This study demonstrates that biochar can help tackle our climate concerns in a major and sustainable way,” says Visiting Professor Stephen Joseph of the University of NSW. Joseph has been studying biochar for 35 years and was the sole engineer in a team of scientists whose work was published in Nature Communications.

The report concluded that biochar could offset 12% of human greenhouse gas emissions in a sustainable fashion. As one of the few technologies that can actually remove carbon dioxide from the atmosphere, rather than simply reducing emissions, biochar could make it possible for nations to become greenhouse-neutral if sufficient changes are made to energy production.

Biochar is produced by burning organic waste at low temperatures in the absence of oxygen. It takes far longer to break down and be released into the atmosphere than compost, and advocates argue that it also forms a better fertiliser. Hydrogen produced during the process can also be used as fuel.

The paper’s authors calculated that global waste biomass such as corn leaves, rice husks and livestock manure could sequester up to 1.8 billion tonnes of carbon in the soil that would otherwise rapidly reach the atmosphere. This equates to 12% of current emissions. A minimum estimate based on the easiest materials to collect represents around half this figure.

Despite the long time it takes for biochar to break down, it does not last forever in soil. Over the course of a century the report estimated that the maximum amount of carbon that could be stored was 130 billion tonnes.

Large-scale biochar production will probably depend on a price on carbon, but biochar could attract a considerable price as a fertiliser, with evidence it can greatly increase crop production (AS, July 2007 p.15). “We’re at the point of knowing it works, but having to refine the technology to know what sorts of biochar go with which soils,” Joseph says.

Progress would be faster, Joseph says, if more funding was available. He contrasts the $1 million given over 3 years to CSIRO to research biochar applications with the hundreds of millions of dollars poured into carbon capture and storage, despite substantially greater evidence for biochar’s sustainable carbon storage capacity.

GM Rice Tolerates Salinity
A strain of genetically modified rice can tolerate salinity by leaving the salt trapped in the root rather than reaching parts of the plant where it can do more damage.

“Rice is the staple food for billions of people around the world,” says Dr Darren Plett of the Australian Centre for Plant Functional Genomics. “Rice is often grown on land that is prone to high levels of salinity. Lands that accumulate salt have lower crop yields, which can threaten the food supply.”

Plett applied a technology that has been used in Drosophila flies to express a gene from the model plant Arabidopsis in the roots of rice but not in other parts of the plant. Although the process of ensuring that the gene is only expressed in the right places is complex, the trait is stable and hence generations of rice can be bred from those that have been modified.

The result, in the laboratory at least, is a higher weight of fresh rice when grown on saline soils. “Most of the work has been done in a variety of rice that is more of a model species for cereals rather than grown commercially,” Plett says. “The genome has been sequenced so it is easy to work on, and we are now working on putting the same gene into varieties that are grown commercially.” Field trials will be conducted at this point to see if the trait works outside the lab.

Plett hopes that the same technique could be used in reverse to increase the nutritional value of rice, causing the roots to pump more iron, nitrogen or magnesium into the rest of the plant rather than trapping it in the root.

Tea Curbs Cancer
Evidence that tea’s health benefits are more than a marketer’s ploy comes from a study of 2700 women, half with ovarian cancer. After controlling for factors such as age, education and smoking, it was found that tea consumption greatly lowers cancer risk.

“Our results indicate that drinking more than four cups a day of black, green or herbal tea may reduce ovarian cancer risk by almost 30%,” says Dr Christina Nagle from the Queensland Institute of Medical Research’s Gynaecological Cancer Group.

Nagle says the study also controlled for dietary variations such as fruit and vegetable consumption.

Ovarian cancer symptoms such as bloating, abdominal pain and irregular bleeding are aren’t specific to the disease. Consequently, by the time most cases are diagnosed the cancer has spread to other organs. This makes ovarian cancer the sixth most common cause of cancer death in Australia, despite being much further down the list by occurrence.

Nagle says that catechins in tea prevent damage to cells, and it is assumed this is the critical factor. These antioxidants are more common in green than black tea, and other research suggests that green teas may be more effective in preventing cancer. However, Nagle says: “Our study did not show a stronger effect for green tea”.

Herbal teas were too small a part of the consumption to figure significantly, but Nagle is skeptical of their benefits as they do not contain high concentrations of catechins.

The work was published in Cancer Causes & Control. Nagle says that not only was there no sponsorship by tea producers, but she has not been contacted by tea companies since the research came out.

Disasters Mapped from Space
The potential for using satellite technology to map and control disasters is being explored in a Chinese/Australian collaboration. A/Prof Andrew Dempster of the University of NSW’s Satellite Navigation and Position Laboratory says that the research uses Synthetic Aperture Radar (SAR) to create three-dimensional maps of the planet. “Currently this is usually done by combining images from successive orbits, but if we could fly satellites close to each other we could do this instantaneously,” Dempster says.

This can be crucial in rapidly changing circumstances, such as a flood. “If the surface changes too rapidly you can’t get good coherence between the two images,” Dempster adds.

The satellites TerraSAR X and TanDEM X were launched separately but have gradually been brought together, and were used to study the recent floods in Pakistan. Up-to-the-minute assessments of flood heights and calibration of flood gauge data could provide evacuation warnings and recommendations on when to release water from dams.

It is relatively easy to fly two satellites one behind the other, but even more detail can be obtained if one satellite is slightly above the other. For example, it would be possible to conduct tomography on the biomass in a forest, revealing the fuel load before a fire and the carbon released afterwards. However, it is a major challenge to construct satellite orbits so that the two stay together, with one above the other, while they pass an area to be studied.

Australia has largely abandoned space research while the rest of the world has moved forward, but Dempster says that pockets of excellence survive. Remote viewing is used heavily in the mining industry, and Australia has expertise in the data analysis, making it a logical area for local specialisation. We are also a world leader in precision agriculture based on satellite data. If these areas can be brought together they may kick-start an Australian space industry, at least for the ground component.

The benefits of having our own satellites are illustrated by an unconfirmed story that during the Black Saturday bushfires researchers had ideas about how satellite sensing could be used to predict fire direction and intensity. However, the story goes that the satellites that Australia sometimes hires were being used by their owners, and requests for them to be diverted to the fire were refused.

Stem Cell Mutations Revealed
Mutagenesis of stem cells has created hope for a better understanding of the causes of some cancers, as well as insights into how stem cells can be put to use restoring organs.

Dr Peter Papathanasiou from The John Curtin School of Medical Research at The Australian National University applied a well-established technique for studying mutations to stem cells for the first time. He applied chemicals known to cause mutations in mouse DNA and investigated the effects on observable features of the rodents’ stem cells.

From there Papathanasiou and his colleagues investigated the genes that might have mutated in these stem cells to produce their unusual characteristics. The work was published in Blood.

Stem cells have a similarity to cancer cells in their capacity to copy themselves, and many biologists believe they represent the key to understanding cancers. The genes in which Papathanasiou found mutations have been implicated in breast cancers, colon cancers and leukaemia. “We’ve shown that blood stem cells with this genetic mutation behave the same way as those present in human bone marrow diseases, including diseases that can evolve into leukaemia,” he says.

Papathanasiou says that if the genes involved in these cancers can be identified, the next stage will be to understand the signalling they use, which may lead to therapeutic drugs that interfere with the signalling, or cause other pathways to fire.

Gene for a Beautiful Mind
A variation of the NRG3 gene has been linked to a specific form of schizophrenia where memory and reasoning are unaffected despite persistent psychotic symptoms.

“The first people to describe schizophrenia never claimed it was one disease. However, people with different presentations can be treated by the same drugs so it has come to be seen as one disease,” says Prof Luba Kalaydjieva of the Western Australian Institute of Medical Research. “However, we are now realising that there is a cluster characterised by profound and pervasive cognitive deficits, and another cluster where, despite the hallucinations, cognition is relatively unaffected.”

Kalaydjieva adds that each cluster appears roughly equally commonly in the community, and that there may be other important variations within the conditions we know collectively as schizophrenia.

The discovery that people with schizophrenia are more likely to have an unusual form of the NRG3 gene is not wholly surprising. Kalaydjieva says that forms of the related NRG1 gene have also been implicated in schizophrenia, and several studies have associated the wider genetic region with psychosis.

Both NRG genes are known to be associated with neuro­development, but Kalaydjieva says that the NRG3 gene is relatively understudied and we don’t know what its normal role is, or how the variation affects its behaviour. Interestingly, however, NRG3 has recently been identified as one of the few points where the DNA of modern humans is different from Neanderthals.

Important as this association is for our understanding of psychosis, Kalaydjieva says that schizophrenia is caused by such a complex mix of genetic and environmental factors that identification of the gene is a long way from being useful to predict clinical outcomes or provide a direct path to new treatments. Nevertheless, she adds: “The better we know, the closer we are to understanding the disease”.

Hope for Motor Neuron Disease
Insight into how neurons interact has raised prospects for treatments of motor neuron disease, once again showing the body to be more complex than previously recognised.

Neurons send signals to each other using packets of neurotransmitter chemicals across cell junctions known as synapses. The number of these packets is important for information flow.

Neurobiologist A/Prof Ian McLennan of Otago University has revealed in Proceedings of the National Academy of Sciences that the receiving neuron controls the number of these packets through the release of the protein TGF-β2.

“We did not predict this, and the finding fundamentally alters our understanding of how communication between cells in the brain’s motor system is controlled,” says McLennan. “It is also likely that this mechanism plays a role in other brain-signalling systems.”

TGF-β2 does not affect the total quantity of neurotransmitter released. However, when TGF-β2 is present, fewer packets are transferred with larger amounts per packets. This makes the signalling more efficient, and allows even diseased neurons to continue transmitting.

The finding arises from research on mice with motor neuron disease. It was known that TGF-β2 has a protective effect, keeping neurons healthy, so it was thought that its application might slow or halt the progress of motor neuron disease. However, McLennan found that giving TGF-β2 to mice with the disease actually reversed the symptoms. “This was totally unexpected. There was no known mechanism,” he says.

The increased efficiency that TGF-β2 provides explains how neurons that had previously ceased to transmit effectively can revive, but obstacles to clinical application remain.

“Unfortunately, while it is harmless to mice, TGF-β2 is known from other studies to be highly toxic when administered to humans. Now that we are aware of how TGF-β2 works we will look for other ways to take advantage of this signalling system to pursue non-toxic therapies,” says McLennan.

TGF-β2 produced naturally travels only very short distances within the body, and never reaches the organs to which it is toxic. One way around the problem would be to ensure that it is applied only where it is needed, but McLennan says there may also be other ways of firing the same mechanism now that its existence is known.

The Price of Promiscuity
There is a price to pay for too much promiscuity. Male guppies that spend too much time having sex with lots of females feed less, grow less and live shorter lives.

Alex Jordan, a PhD student at the University of NSW, put some of the Trinidadian fish in tanks with one female per male while in other tanks the males were frequently provided with new females. The males in these tanks might have been happier, but they never grew as large and died younger.

“Our research revealed that males pay a significant cost of promiscuity that places an upper limit on the number of sexual partners they can have throughout their lifetime,” says Jordan. “Perhaps it’s nature’s way of telling males to be more faithful to their sexual partners.”

This is the first lifetime study of the costs of reproduction for a male vertebrate. The work, published in the Journal of Evolutionary Biology, is one component of Jordan’s thesis on the costs of male reproductive strategies. In another study he examined whether male social fish in the wild chose a group that offered them more immediate sexual opportunities, or another group where the risk of being eaten by predators was lower. He found that the fish preferred to stay alive and gain opportunities to mate further down the track.

The findings are not particularly surprising. The fact that males of some species are largely monogamous indicates that there is an evolutionary advantage to this approach. Jordan notes that this is greater in species where fathers invest significant effort in raising their young.

Jordan acknowledges that one cannot extrapolate too far from fish to other vertebrates, particularly humans. However, he notes that guppies are unusual fish since females “invest significant energy in the young, while the males invest very little”. He also observes that there are parallels with human behaviour, where promiscuity may lead males to risky behaviour or at least financial costs.

Given the price they had to pay one may wonder why the male guppies took up the opportunity to mate with every female rather than becoming selective. Jordan acknowledges that this may be because they evolved in an environment where mating opportunities are rarer, so it was best to take everything that came along.

He is currently researching whether male guppies that get used to having ready access to new females learn to curtail the mating instinct.

Garlic and Dairy Are Good for the Heart
Garlic appears to help lower blood pressure for people with hypertension, although aged garlic extract is more effective than the raw or cooked product. In more surprising results, full-fat dairy may contribute to a reduction in deaths from cardiovascular disease.

Dr Karin Ried from the University of Adelaide found a drop in systolic blood pressure of more than 10 mm Hg for people with high blood pressure (over 140 mmHg) who had taken garlic capsules for 12 weeks compared with those given placebos.

“This reduction is clinically significant, as a drop in systolic blood pressure by 5 mm Hg reduces the risk of cardio-vascular disease by 8–20%,” Ried says. “Garlic is thought to have an antihypertensive effect because it stimulates the production of nitric oxide and hydrogen sulfide, which helps relax blood vessels.”

Ried notes that 30% of Australian adults are hypertensive, but only half are on blood pressure medication even though high blood pressure is an important risk factor for cardiovascular disease.

Ried has previously published results indicating that dark chocolate reduces high blood pressure. While the garlic data is not a surprise, and dark chocolate has been shown to be good before, full-fat dairy is a more improbable saviour.

However, Dr Jolieke van der Pols of the Queensland Institute of Medical Research says that after following 1500 Australians for 16 years “we found that people with the highest intake of full-fat dairy had 70% less chance of death by heart disease or stroke than those who had the lowest intake of full-fat dairy. It is possible that milk fat may contain nutrients that counteract the expected negative effects of the saturated fat in dairy products.”

The results are made more puzzling by the fact that the overall decrease in death rates among dairy consumers was not significant, but there was also no statistically significant rise in deaths from any other cause.

Northern Mammals under Threat
Three environment groups have enabled scientists to release a report documenting the decline of native mammals across northern Australia.

“This is something which is well-known amongst mammal scientists, but hasn’t gained a lot of public attention,” says Dr James Fitzsimons of The Nature Conservancy. “Based on current trends, many native mammals will become extinct in northern Australia in the next 10–20 years.”

In February 2009, 40 specialists attended a workshop to look at published papers on the topic and share unpublished data. The report, Into Oblivion: The Disappearing Mammals of Northern Australia, is the result.

The problem is worst in unprotected areas, but even in Kakadu 136 plots showed a 65% decline in species richness and a 75% reduction in the number of individual mammals over a 6-year period.

Quoll declines as a result of cane toad expansion have attracted attention, but Fitzsimons says that the three major causes across most species are thought to be feral cats, grazing and inappropriate fire regimes. While fires were once lit at the start of the dry season, many areas now remain unburnt, leading to hotter, larger fires later on (AS, August 2005, p.47). Fitzsimons says that these larger fires make it harder for mammals to recolonise territory.

Disease remains a possible, but debated, factor.

The best-documented decline is that of the brushtailed rabbit rat, but others becoming rare include the fawn antechinus, the northern brown bandicoot and the now erroneously named common brushtail possum.

America Teaches the Whole World to Sing
New Zealand musicians accused of lacking authenticity for singing in American accents have been unfairly maligned, a researcher has concluded. In fact, America has dominated the global pop scene to such an extent that people the world over sing in American tones without even realising it.

For his Masters at Auckland University of Technology’s Institute of Culture, Discourse and Communication, Andy Gibson asked participants to sing lyrics and then recite them. “There were huge differences between the sung and the spoken pronunciation of the same words,” says Gibson. “Studies in the past have suggested that non-American singers wilfully put on American accents but my research suggests the opposite – that an American-influenced accent is the default when singing pop. We do it automatically.”

Gibson believes that accent varies with the style of music being played. An example is Jamaican accents creeping into reggae singers who have never visited the Caribbean. “It actually requires effort to do something different,” Gibson says.

“The American accent doesn’t stick out in singing because we are so used to hearing it.”

Clean Money
University of Ballarat researchers have stripped away one of the few comforts of being poor – the idea that money is loaded with bacteria.

After analysing banknotes from ten nations Dr Frank Vriesekoop concludes: “The richer and more developed countries had fewer bacteria on their money than poorer countries”.

Australia’s polymer banknotes, which are also used in New Zealand and Mexico among the countries studied, carried fewer bacteria than the cotton paper notes used elsewhere.

“Older notes are more wrinkled, so that dirt and bacteria can easily nestle in the folds of the notes,” says Vriesekoop. Wealthier nations and those measured as being economically free and having low corruption had cleaner currency, possibly because notes were taken out of circulation more quickly.

Vriesekoop recommends that the handling of food and the collection of money should be physically separated, and if possible done by different people.

Nevertheless, even the oldest and most grimy cotton currency proved safe. “Nowhere in the world were alarming levels of pathogenic bacteria found on money,” Vriesekoop says.

All of which just goes to prove the old line: money may make you sick, but not having it certainly makes you sicker.