Plumbing key to flowering plants’ evolutionary success

The evolution of an efficient water transport system may be how flowering plants came to dominate terrestrial plant life 60-70 million years ago.

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Nanochip technology could revolutionise medicine

By Liz Tay
Photons, instead of electrons, are key to a newly developed nanochip manufacture technique that is three times as precise as conventional methods.

The technique has been dubbed ‘absorption modulation’. It is based on photochromism, which is the ability of some materials to change their colour in response to certain wavelengths of light.

By exposing the photochromic material to patterns created by interfering beams of light, researchers have created lines just 36 nanometres wide -- approximately one-tenth as thick as the wavelength of light used to create them.

The patterned photochromatic material is then used on top of a conventional ‘photoresist’ that is used to coat a silicon wafer, forming a chip.

Lead researcher Rajesh Menon explained that the absorption modulation method creates patterns on a photoresist in a similar manner to how black and white photos are printed from negatives.

“We are creating an image of a pattern on a photosensitive material using light,” said Menon, who is a research engineer at the Massachusetts Institute of Technology.

“[This is] analogous to old-school photography, but, of course at the nanoscale,” he said.

Menon expects his method to be competitive with scanning-electron-beam lithography, which is commonly used to pattern photoresists in today’s semi-conductor industry.

However, by using light instead of electrons, Menon said his technique could be faster, more accurate, and less likely to interfere with fragile samples such as biological samples.

The technology will be commercialised via an MIT spin-off company, LumArray. Already, the researchers have had ‘some discussion’ with chip manufacturers, and Menon expects to achieve commercial production within five years.

The researchers also are pursuing ways of using the technique to create even smaller patterns, down to the scale of individual molecules.

As well as paving the way for advances in nanophotonics, nanofluidics and nanoelectronics, the technology could significantly improve optical microscopy, allowing future researchers to make more detailed biological or material observations.

“The impact here could be substantial as this would enable biologists to peer at proteins with nanoscale resolution, potentially revolutionising medicine,” Menon said.

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Do fruit flies have free will?

By Liz Tay
In scientific spheres, insects have a reputation similar to that of complex robots that respond predictably to their surroundings. However, a new study has claimed that fruit flies might not be as simple as previously believed, and could actually exhibit free will.

The concept of free will has been a topic of debate, even in relation to humans. Some scientists believe that the purpose of human consciousness is merely to rationalise every decision made by chemical processes in the brain a few milliseconds after the fact. Others believe that once enough is known about the human brain, it will be possible to explain and even predict a person’s behaviour.

"Given this strong claim for humans, it is surprising if prediction should be principally impossible in flies," said Björn Brembs, a biologist from the Free University Berlin and senior author of the fruit fly study. "[But] our work shows that for flies such a prediction will not be possible to the extent claimed."

Together with an international team of researchers, Brembs tethered fruit flies in completely uniform white surroundings and recorded their turning behaviour. In this setup, the flies do not receive any visual cues from the environment, and since they are fixed in space, their turning attempts have no effect.

Without any external stimuli from their surroundings, the scientists expected the flies’ behaviour to resemble random noise, similar to a radio tuned between stations. However, researchers observed the flies behaving non-randomly.

The researchers then tested a plethora of increasingly complex random computer models, all of which failed to adequately model fly behaviour, leading to the conclusion that variability in fruit fly behaviour is not due to simple random events, but is generated spontaneously and non-randomly by the brain.

Björn Brembs came up with the idea to study spontaneous behaviour almost 10 years ago in 1998, as part of his work on operant conditioning. However, as he lacked the tools required to conduct experiments, the study was put on hold until late 2004, when discussions with colleague Mark Frye sparked his interest in fruit flies.

As a biologist, Brembs is interested in the biological aspects that might enable or prevent the existence of free will. While he believes that absolute freedom is impossible, Brembs questions the extent to which humans and animals are free, and expects this to be where the species differ.

"Scientifically, the most important aspect is that we found evidence for a brain function which appears evolutionarily designed to always spontaneously vary ongoing behaviour," Brembs explained.

"There is tentative evidence that such a function may be very widespread in the animal kingdom, including humans. If this were indeed the case, we might
have discovered the first evidence for something truly fundamental," he said.

The next step will be to use genetics to localize and understand the brain circuits responsible for the spontaneous behaviour. This step could lead directly to the development of robots with the capacity for spontaneous non-random behaviour and may help combating disorders leading to compromised spontaneous behavioural variability in humans such as depression, schizophrenia or obsessive compulsive disorder.

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Curbing deforestation could stop climate change - if it exists

By Liz Tay
The effect of human activities on climate change is real, according to a new study on tropical deforestation in areas like the Amazon and Indonesia.

Conducted by an international team of researchers from the U.S., U.K., Brazil, France and Australia, the study claims to have confirmed that avoiding deforestation can play a key role in reducing future greenhouse gas concentrations.

Nearly 20 percent of carbon emissions is said to be contributed by deforestation in the tropics. This equates to about 1.5 billion tonnes of carbon each year, adding up to an estimated 130 billion tonnes of carbon by the year 2100.

"[The 2100 projection] is greater than the amount of carbon that would be released by 13 years of global fossil fuel combustion," said CSIRO atmospheric scientist Pep Canadall, who is also a researcher on the Global Carbon Project and on the deforestation study.

"Maintaining forests as carbon sinks will make a significant contribution to stabilising atmospheric greenhouse gas concentrations," he said. "The new body of information … also demonstrates the need to avoid higher levels of global warming, which could slow the ability of forests to accumulate carbon."

"Climate changes all the time, so if the goal is to keep it constant, or 'sustainable', it is a hopeless task"
- Bjarne Andresen

According to thermodynamics expert Bjarne Andresen, however, the very concept of global warming could be a farce. A professor of physics at the esteemed Niels Bohr Institute in Denmark, Andresen's recent report in the international Journal of Non-Equilibrium Thermodynamics claims that the notion of an overall global temperature is both a thermodynamical and mathematical impossibility.

Explaining 'temperature' as a comparative quantity that can only have meaning at a point or for a homogeneous system, Andresen argued that Earth consists of a huge number of components. Adding temperatures together to form a global average would have the same, meaningless effect as calculating the average phone number in a telephone directory, he said.

"The whole idea of global anything is a figment of the imagination," he said. "Effects happen locally and will be different at different spots on Earth; some places will heat up, others cool down."

"Climate changes all the time, so if the goal is to keep it constant, [or] 'sustainable', it is a hopeless task," he said, although stressing that the futility of a constant climate is his personal opinion, and not part of his scientific work.

While he is also of the opinion that humans are ethically obliged not to pollute the environment with poisonous substances like PCB and mercury, Andresen questioned the purpose of using wood, which has sometimes been touted as renewable energy source, instead of coal.

"What is the big difference between the so-called renewable energy source wood as opposed to coal?" he said. "Coal used to be wood as well, so we are actually just burning old wood. In both cases the carbon originally came from the atmosphere and we are returning it there."

Andresen urged climatologists to rethink their methods of analysing climate, as 'equally correct' methods of averaging could each yield wildly different conclusions about the state of the environment.

Emphasising that strong physical arguments are needed to decide on which averaging method to use in describing the climate, Andresen argued that currently approaches to 'global warming' could be employing more of a political, fear-mongering tactic than a scientific approach to the issue.

Atmospheric physicist Michael Box, of the University of New South Wales, defended the averaging methods currently favoured by many climatologists, saying that while 'average temperature' may be a term used loosely by policy makers, 'real' climate scientists use a vast range of inputs as best they can.

"I'm sure all atmospheric physicists know that you can't average temperatures in a strictly formal sense," he said. "However, it is a piece of data that we have going back for a century, so we have something we can compare to."

"We all know that it is temperature gradients which drive the atmosphere - i.e. meteorology," he said. "Nevertheless, an increase in global average temperature is a clear sign that something is going on!"

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Happy feet hit treadmills to track climate change

By Liz Tay
They may not be able to tap dance, but king penguins in the Antarctic could in fact have a role in monitoring the effects of climate change, new research suggests.

Scientists have long studied our changing environment in terms of unusual animal behaviour, such as altering patterns of fish and bird migration. Now, a research team from the University of Birmingham is finding out if the energy requirements of king penguins could be used as an alternative bio-indicator to monitor the health of the environment.

King penguins predominantly feed on a variety of fish called myctophid fish, explained bioscientist Lewis Halsey, who led the research on Possession Island in the South Indian Ocean. As the Southern Oceans warm, these fish tend to migrate further South, and away from the Islands inhabited by king penguins, he said, which makes hunting more difficult for the penguins.

“As the king penguins have to work harder to forage for the fish, their energy expenditure in doing so will increase,” Halsey said. “[This tells] us that the myctophid fish are changing location and becoming more sparse in areas of the Southern Oceans where king penguins forage.”

King Penguin - Lewis HalseyKing penguins are good candidates as bio-indicators for several reasons, the researchers say. Firstly, while at sea foraging, they cover hundreds of kilometres and are able to dive to depths of several hundred metres, so they explore a relatively large portion of the expansive Southern Oceans. Secondly, the diets of several populations of king penguins are well known. Thirdly, while foraging for food is done at sea the penguins also come ashore to breed and moult, making them accessible to researchers.

To ascertain the penguins’ energy requirements, researchers have implanted miniature heart rate data loggers into the birds. The penguins’ heart rates are then collaborated against energy expenditure under laboratory conditions, by getting the penguins to walk on a treadmill at different speeds. This data provides a correlation between heart rate and rate of energy expenditure, so any heart rate data subsequently obtained when the king penguins go to sea to forage can be used to estimate energy expenditure.

“We have deployed these loggers on birds for several years so we can look to see if the energy expended by king penguins from year to year is changing, which may give us information on the availability of myctophid fish in the Southern Oceans each year,” Halsey said.

More data is needed from the heart rate loggers during the next few years before any long term trends can be established. If the energy expended by king penguins at sea increases over time, it is likely that myctophid fish are getting harder to come by, which could be due to the warming of the Southern Oceans, Helsey said.

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Cane toads invade new Australian terrain

By Liz Tay
As the nursery rhyme goes, there was an old lady who swallowed a fly. To catch the fly, she swallowed a spider. To catch the spider she swallowed a bird … and so on, until she died, of course.

Cane toads first reached Australian soil under similar premises. When they were introduced to the Northern Territory in 1935, they were expected to combat the cane beetle, which is a pest of sugar cane crops. While the toads did not alleviate the problem with beetles, they did quickly become accustomed to the Australian climate, and they bred fast. Farmers soon found themselves faced with larger, wartier pests than cane beetles – the cane toads themselves.

For the past 70 years, residents of Perth and Adelaide have watched cane toads spread from the Northern Territory through tropical Australia, and thought it had nothing much to do with them. But new research by an international team of scientists, including ecologist Rick Shine of the Sydney University’s School of Biological Science, claims otherwise.

March of the toads

Previous predictions about the behaviour of cane toads, which go by the scientific name Bufo marinus, indicated that the species would be limited to tropical environments like those in Central and South America, from which the toads were originally imported.

Confounding these beliefs, the toads were now found to have adapted to dry conditions and temperatures ranging from 5 to 27 degrees Celsius.

“The toads have adapted rapidly to Australian conditions, and now tolerate much higher temperatures than was the case when they first arrived on our shores in 1935,” Shine said. “As a result, toads have managed to spread much further, into climatic zones also found widely through southern Australia – so there is no reason to think they will remain only in the tropics.”

Mathematical modelling by Shine and his team shows now predicts that toads will be able to live and breed in large areas of Western Australia, South Australia and western Victoria, and in several pockets along the New South Wales coast.


Current and projected range of invasive cane toads in Australia - Rick Shane et al

The researchers estimate the toads’ range to be about 1.2 million square kilometres across the Northern Territory and Queensland. This is a dramatic increase from estimates made by the same research team a little over a year ago, in which cane toads were thought to have spread to more than a million square kilometres in tropical and sub-tropical Australia.

Additionally, the rate at which cane toads are invading is not only fast – it’s also getting faster, researchers found. Compared with a rate of only 10 kilometres a year in the 1940s, the toads are now found to be advancing at more than 50 kilometres annually. Researchers speculate that this could be a result of evolution, as toads with longer legs were found to have an evolutionary advantage over shorter-legged counterparts.

Beware warty hitch-hikers

Most of the potential range of the cane toad in southern Australia is separated from the toads’ tropical range by very large expanses of desert, which the researchers expect to be too dry for a toad to cross.

But although the toads may initially be deterred by these dry expanses, Shine said it is likely that the toads will cross such areas as hitch-hikers among rubbish or equipment in the back of a truck.

According to Shine, a nationwide invasion of cane toads is ‘inevitable’.

“[The arrival of cane toads] will probably depend upon fortuitous hitch-hiking events, rather than the toads dispersing all the way under their own steam,” he said. “The toads are superb invaders, and so far, none of the attempts to slow them down seem to have been very successful.”

Due to their toxicity and eating habits, the arrival of cane toads could spell bad news for some native fauna, pets and large predators. However, Shine expects most species to be relatively unaffected.

“Our work in the Northern Territory indicates that the toads dramatically affect only a few species,” he said, “[which are] mostly large predators like goannas, that try to eat the toads and are poisoned as a result.”

The spread of cane toads is expected to provide a good model system for understanding what invasive species will do in general, Shine said. Researchers are now expecting similar shifts in other invaders as well, as they adapt to the Australian climate.

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Genetically modified pigs could yield organs for human bodies

By Liz Tay
Recent medical advances may shine new hope on the otherwise dismal shortage of human organ donors, by allowing the organs of animals to be transplanted into human bodies instead. It may be awhile yet before the technology, known as xenotransplantation, reaches medical clinics; but when that happens, accusing someone of being pigheaded may take on a new meaning altogether.

Xenotransplantation has been studied and attempted for over a century, but few operations have been successful to date. According to Muhammad Mohiuddin, who studies xenotransplantation at the U.S. National Heart, Lung, and Blood Institute (NHLBI), the major stumbling block of existing techniques is that the immune system in the animal receiving the organ tends to reject the transplant.

"We are still learning about new immunological hurdles and have to overcome these barriers in non-human transplant models," Mohiuddin said.

To study these immunological issues, scientists have studied xenotransplantation across several animal combinations, including the insertion of hamster organs into rats, and later into mice, as well as the transplantation of organs from pigs to baboons.

In a recent paper published in the esteemed journal PLoS Medicine, Mohiuddin cites a study in which insulin-producing cells, called islets, from pigs were transplanted into monkeys with diabetes. This led to the complete reversal of diabetes for over 100 days, researchers said.

However, suppressing immunological issues in the pig-to-monkey studies involved giving the monkeys drugs called immunosuppressants in doses that would be too large to be administered in humans. To overcome the need for overly large amounts of immunosuppressants, Mohiuddin suggests organs be farmed from pigs that are genetically modified to be more compatible with humans.

"Taking out some molecules which are immunogenic to humans and putting in human molecules [in the pig] will make the pig organ more compatible to humans," he said. "This allows us to use safer immunosuppression methods, which are now routinely used in allotransplantation [organ transplantation from human to human]."

Pigs were chosen as potential donors for their organ size, which is said to be comparable to human organs, their short breeding cycle and large litter size, and our ability to genetically manipulate their immune system, Mohiuddin explained.

While there are still some hurdles between current research and the potential use of pigs in human organ donation, such as the objections of animal rights proponents and concerns to do with the transmission of viruses across species, Mohiuddin believes there is a strong case for further research into xenotransplantation.

"In [the] United States alone there are more than 90,000 patients waiting for organ transplantation and only 25,000 transplants were performed during last year," he said. "Most of these patients will die waiting for the organs."

"Xenotransplantation has the potential to save many lives," he said.

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SciNet News launches!

SciNet News is published by Liz Tay, a physicist turned journalist at the University of Technology, Sydney.

Operating on the premise that science is fun (really!), SciNet News encompasses topics ranging from the asexuality of amoeba to the zeroth law of thermodynamics.

Ideas and contributions are always welcome. Contact scinetnews AT liztay DOT net.

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