Archive for April, 2008

Unconscious brain activity shapes our decisions

By Ed Yong | April 13, 2008 1:01 pm

Blogging on Peer-Reviewed ResearchOur brains are shaping our decisions long before we become consciously aware of them. That’s the conclusion of a remarkable new study which shows that patterns of activity in certain parts of our brain can predict the outcome of a decision seconds before we’re even aware that we’re making one.

Redpill.jpgIt seems natural to think that we carry out actions after consciously deciding to do so. I decide to start typing and as a result, my hands move around a keyboard. But according to modern neuroscience, that feeling of free will may be an illusion. For over twenty years, experiments have suggested that, unbeknownst to us, a large amount of mental processing goes on in unconsciously before we become aware that we intend to act.

The first such study was done by Benjamin Libet in 1983. Libet asked volunteers to press a button at a time of their choice, and to remember the position of the second hand of a wristwatch when they first felt the urge to move. While this happened, Libet measured the activity of their supplementary motor area (SMA), a part of the brain involved in planning movements. Astonishingly, he found that the SMA  became active about half a second before the volunteer felt a conscious desire to press the button.

The seminal experiment suggested that the brain makes decisions on a subconscious level and that people only believe that they consciously drove their actions in hindsight. The experiment seemed to put a dent in beliefs about free will and understandably, it has proved to be controversial. Some have criticised the techniques that Libet used, claiming that inaccurate measurements could explain that the small gap between brain activity and conscious awareness.

For those who were convinced by the experiment’s results, a slew of important questions remained. Is the SMA the source of the decision, or is it responding to other parts of the brain even higher up the chain of command? And is this unconscious activity a sign that the relevant areas of the brain are revving into readiness, or does it actually predict the action that is eventually taken? Now, Chong Siong Soon and colleagues from the Max Planck Institute have addressed these queries with an elegant update of Libet’s work.

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Bacteria inspire drug that protects against radiation sickness

By Ed Yong | April 11, 2008 8:20 am

Blogging on Peer-Reviewed ResearchFor comic book characters, big doses of radiation are a surefire way of acquiring awesome superpowers, but in real life, the results aren’t quite as glamorous. A victim of acute radiation poisoning can look forward to hair loss, bleeding, the destruction of their white blood cells and bone marrow, and severe damage to their spleen, stomach and intestines.

Mushroomcloud.jpg
Radiation doesn’t kill cells directly, but it can cause so much damage that they commit suicide, by enacting a failsafe program called apoptosis.  Now, Lyudmila Burdelya and colleagues from Roswell Park Cancer Institute have found a way to block this cellular kill-switch, using a drug inspired by the unlikeliest of sources – the tail of the food-poisoning bacterium, Salmonella.

In early animal tests, the drug saved the lives of monkeys and mice that had been exposed to lethal doses of radiation. With further development and clinical trials, it could be used to protect cancer patients undergoing radiotherapy, or even people who are more inadvertently exposed through accidents or nuclear attacks.

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When bacteria merge – two species are turning into one

By Ed Yong | April 10, 2008 2:00 pm

Blogging on Peer-Reviewed ResearchHumans have been blamed for the disappearance of species before but never quite like this. Scientists at the University of Oxford have found evidence that two species of bacteria are merging into one. The two species are swapping genetic material at such a high rate that they are on the road to sharing a single, common genome. Their genetic merger is probably the result of being thrust into a new environment – the intestines of heavily farmed chickens, cattle and other domesticated livestock.

Campylobacter.jpgThe two bacteria in question – Campylobacter jejuni and Campylobacter coli - are two of the most common causes of gastroenteritis, or food poisoning, in the world. They infect a broad range of animals including mammals, birds and even insects. The two shared a common ancestor and their housekeeping genes – essential genes that are always switched on – are about 87% identical. They are currently recognised as separate species but it looks like some populations are headed back towards a unified direction.

To swap or not to swap

Classifying bacterial species and building family trees for them is never straightforward. Unlike multi-celled creatures, which must content themselves with passing genes on to their offspring, bacteria can happily trade genetic material with their neighbours through a process called conjugation.

Earlier experiments from the lab of Martin Maiden showed that C.jejuni and C.coli are indeed exchanging genetic material. Samuel Sheppard, working in Maiden’s lab, carried on the work by comparing the sequences of seven housekeeping genes in almost 3,000 samples from the two species, taken from a wide range of locations.

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CATEGORIZED UNDER: Bacteria, Evolution, Speciation

Calling all Londoners

By Ed Yong | April 9, 2008 4:56 am

A couple of social things: A couple of mates, Ruth Francis and Henry Scowcroft, have devised the best Facebook group ever – the Campaign to replace the voice on the Tube with David Attenborough’s voice (the Tube is London’s subway system for all you non-Brits). In their words:

So now Life in Cold Blood is over, and the great man has hung up his broadcasting boots for good, what better tribute than to replace the starchy, boring voice on the London Underground with the silky, enthusiastic utterances of Sir David Attenborough. Ever since we were tiny, Sir David’s trademark “THIS… is a ” has had us pricking up our ears for the fascinating facts to follow. Surely, a national institution such as he is deserves such immortalisation. People, pledge your support below. If you need convincing, take a moment and just imagine Sir David intoning the following… “THIS… is Bank. Change here for the Northern, District and Circle lines… and the Waterloo and City Line”.

It seems that there’s certainly a vacancy so go and sign up. And while you’re at it, have a look at the interview I did with Sir David early this year.

Meanwhile, if any of you are free tonight, a bunch of science bloggers are meeting up for a drink in London, near the Natural History Museum. We’ll be at the Queen’s Arms from about 6.30. If we haven’t met, I’m the one in the photo on the top left (not the stuffed monkey, the other one).

Your regularly scheduled blogging will return tomorrow. I’ve been slightly derailed by the desperate need for sleep, triggered by having to do 15 back-to-back live radio interviews from 7-9 yesterday morning.

CATEGORIZED UNDER: Personal

Automatic "evolution machine" creates more efficient enzymes on a microchip

By Ed Yong | April 7, 2008 8:01 pm

Blogging on Peer-Reviewed ResearchOur bodies are serviced by a huge workforce of enzymes, which speed up the chemical reactions that rage within our cells. These enzymes have been crafted into a vast array of shapes and functions over millions of years of evolution but new ones can be generated on a microchip using the same principles.

Early attempts to design proteins from scratch resulted in fairly crude enzymes that were outperformed by nature’s more elegant and finely-tuned efforts. Scientists have since developed more efficient artificial enzymes using the same evolutionary principles that generated naturally occurring ones. The process involves mutating an initial pool of enzymes to get a varied mix, testing them for an ability-of-choice, and weeding out the most successful ones for further development.

Microfluidics.jpgThis is laborious  and time-consuming work, and it requires the attention of experimenters at every step of the way. It’s also not quite as elegant as a biologist might like. If designing proteins from scratch seems a bit like the work of a creator, then checking and steering the development of evolving proteins is rather like the work of an intelligent designer. A more Darwinian system would apply a set of rules to some starting ingredients and let events unfold without tampering.

That’s exactly what Brian Paegel and Gerald Joyce from the Scripps Research Institute have done. They have created an automatic “evolution machine” that drives the evolution of an RNA enzyme without any human direction. All the experimenter has to do is to set some initial conditions, provide the ingredients and switch the machine on.

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CATEGORIZED UNDER: Biotechnology, Evolution

First lungless frog discovered in Borneo

By Ed Yong | April 7, 2008 12:01 pm

Blogging on Peer-Reviewed ResearchThe invasion of land by the tetrapods – four-limbed animals that include mammals, reptiles and amphibians – was surely one of the most evocative events in animal evolution. The march onto terra firma began some 365 million years ago and was driven by a suite of innovative adaptations that allowed back-boned animals to live out of water.

Flat_headed_frog.jpgLungs were among the most crucial of these for they allowed the first land-lubbers to extract oxygen from the surrounding air. That ability is so important that it’s rare for tetrapods to lose their lungs completely. Until now, the only groups that we know have done so are two families of salamanders and a lone species of caecilian (a type of burrowing worm-like amphibian).

Now, David Bickford and colleagues form the National University of Singapore have expanded that list with the discovery that a species of frog – the Bornean flat-headed frog (Barbourula kalimantanensis)- also lacks lungs of any sort.

The small species, also known as the Kalimantan jungle toad, is one of the most primitive of all frogs. It’s almost completely aquatic and lives in fast-flowing streams on the island of Borneo. Bickford found nine specimens on a recent expedition to the island in 2007 and before then, only two specimens had ever been found in almost 30 years of searching. Through dissections carried out right there in the field, Bickford confirmed that the frog has no lungs.

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CATEGORIZED UNDER: Amphibians, Conservation

Ed's writing causes end of civilisation?

By Ed Yong | April 6, 2008 6:46 pm

NewScientist.jpg
I’m amused to learn that last week, New Scientist published a feature article of mine for the first time and this week, the magazine’s cover proclaims the collapse of civilisation. Coincidence? You decide…

Thanks to my father-in-law for the keen observation :-p

CATEGORIZED UNDER: Personal

Super-bacteria eat antibiotics for breakfast

By Ed Yong | April 3, 2008 2:00 pm

Blogging on Peer-Reviewed ResearchAntibiotics are meant to kill bacteria, so it might be disheartening to learn that some bacteria can literally eat antibiotics for breakfast. In fact, some species can thrive quite happily on nothing but antibiotics, even at high concentrations.

Bacteria.jpgThe rise of drug-resistant bacteria poses a significant threat to public health and many dangerous bugs seem to be developing resistance at an alarming rate. The headline-grabbing MRSA may be getting piggybacks from livestock to humans, while several strains of tuberculosis are virtually untreatable by standard drugs.

But a startling new study reveals just how widespread antibiotic resistance really is. Gautam Dantas from Harvard Medical School managed to culture antibiotic-eating bacteria from every one of 11 soil samples, taken from farmland and urban areas across the US. All eleven were positively loaded with a diverse group of bacteria that were extremely resistant to a wide range of antibiotics at high concentrations.

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Climate change knocked mammoths down, humans finished them off

By Ed Yong | April 2, 2008 7:58 pm

Blogging on Peer-Reviewed ResearchDid our ancestors exterminate the woolly mammoth? Well, sort of. According to a new study, humans only delivered a killing blow to a species that had already been driven to the brink of extinction by changing climates. Corralled into a tiny range by habitat loss, the diminished mammoth population became particularly vulnerable to the spears of hunters. We just kicked them while they were down.

Mammoth.jpgThe woolly mammoth first walked the earth about 300,000 years ago during the Pleistocene period. They were well adapted to survive in the dry and cold habitat known as the ‘steppe-tundra‘. Despite the sparse plant life there, the woolly mammoths were very successful, spreading out in a belt across the Northern hemisphere.

Their fortunes began to change as the Pleistocene gave way to the Holocene. The climate around them started to become warmer and wetter and the shrinking steppe-tundras greatly reduced the mammoth’s habitats. The species made its last stand on the small Wrangel Island in Siberia before finally succumbing to extinction.

But climate change isn’t the whole story. About 40,000 years ago, those relentless predators – human beings – started encroaching into the woolly mammoth’s range in northern Eurasia. Which of these two threats, climate change or human hunters, sealed the mammoth’s fate?

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Carnivals

By Ed Yong | April 2, 2008 1:21 pm

It’s carnival time! Here are four excellent round-ups of blog posts for your scientific delectation.

CATEGORIZED UNDER: Uncategorized
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