Nature Newsblog
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Satellite observations suggest climate models are wrong on rainfall.
Global warming will increase worldwide precipitation by three times the amount predicted by current climate models, according to a study based on two decades' worth of satellite observations.
Read more here.
Tree-dwellers can benefit from standing on two legs.
A study of orangutans walking through the tree-tops suggests that humans' ancestors may also have first stood upright in the trees, say researchers.
Read the story here.
Triangulation technique spots object at the edge of our Galaxy.
Astronomers have used telescopes on Earth and in space to nail the precise position of a mysterious, dark object at the outer edge of our Galaxy. The work could be an important step in understanding so-called dark matter — mysterious material that makes up about a quarter of our Universe.
Read the story here.
Single receptor responds to cold and menthol.
As an ice cream melts in your mouth this summer, take a moment to contemplate the protein that may be bringing you that sense of cool relief — and numbing your tongue. Researchers have pinned down that particular protein in mice, and think that a similar one in humans does the same job.
Read the story here.
Authors accuse agency of putting politics before health.
Two new books are forcing the United Nations' AIDS programme to defend itself against claims that politics have distorted its mission.
Read the story here.
This week the Nature Podcast spots water vapour in a planetary birthplace, chills out with a cold receptor, and nets five new breast cancer genes.
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Members of the Caudwell Xtreme Everest expedition, testing human adaptation to hypoxia on the roof of the world, write a diary blog for Nature from 30 March, 2007.
The South Col (Camp 4), at 7950m above sea level, is the most inhospitable place I have ever been to.
It lies as a saddle between the peaks of Lhotse and Everest. Wind funnels through this gap in the mountains continuously, scouring snow from the ground and projecting it horizontally at high speed. A number of tents are normally to be found huddled together at the bottom of the route which leads up to the summit of Everest.
Traditionally climbers arrive at the South Col, from camp 3, in the early afternoon. They rest and brew up drinks until early evening when they leave for the summit. On their return the camp is dismantled and the climbers descend as rapidly as possible. The aim is to spend as little time as possible on this litter strewn wasteland. Our aim was to set up a physiology laboratory on the Col, and spend a number of days trying to study as many of our investigators as possible.
Once the Sherpas had erected a suitably sized tent on the Col we set about trying to construct the world’s highest laboratory. The first hurdle was a reliable source of electricity from which to run the various pieces of equipment we intended to use. A bank of 12 volt batteries fed by solar panels mounted on the outside of the tent was the answer to this. Despite the howling gales one useful natural phenomenon at the South Col is sunlight; glaring rays beam down from dawn until sunset.
Then we needed to build the exercise bicycle which forms a vital component of the cardiopulmonary exercise (CPX) testing system. The bike had to be brought to the South Col in small pieces as the whole bike would be far too heavy and cumbersome for any Sherpa to carry up the steep Lhotse Face. Wearing oxygen masks and following simple instructions with plenty of photos we slowly pieced together the bicycle without damaging any of its delicate internal components.
Next the breath-by-breath analysis system needed to be calibrated to the thin cold air which is to be found 8000m. The missing link that co-ordinates the bicycle and the breath analysis system is a laptop computer. For those of you who have attempted research at altitude you will know that computer hard drives begin to fail after about 4500m. To get around this we had to make special hard drives from the memory cards more commonly found in cameras. To our amazement the laptops worked at this extreme altitude; the highest a computer has ever been successfully used on Earth, as far as we know! Numerous other pieces of research equipment were unpacked and warmed up ready for the subjects to be investigated.
After multiple glitches we eventually managed to perform the highest CPX tests ever. Subjects cycled to exhaustion whilst we measured systemic oxygen consumption. Needless to say, the maximum work load achievable by subjects was considerably less than they achieved at lower altitudes. Other tests included transcranial Doppler measurement of middle cerebral artery blood velocity (blood flow speed to the brain), near infra-red spectroscopy to assess brain oxygenation, neurocognitive assessments (higher brain function), sidestream-darkfield imaging of the sublingual microcirculation (blood flow under the tongue) and spirometry (lung function measurements). Considering the appalling conditions outside the tent we managed to complete a fairly extensive series of experiments in the limited time we could stay at the Col .
There remained one more experiment to perform, an arterial blood gas sample from the summit of Everest. We left the South Col at around nine thirty on the night of the 22nd May and began the long, cold, slow climb up towards the summit. We climbed through the night and as the sun began to rise we came face to face with the famous Hilary Step. Having conquered this final hurdle we arrived at the summit of Mount Everest (8848m) at around six thirty in the morning of the 23rd May.
It was cold and windy but worth every step of the arduous journey we had taken to get there. We decided that taking an arterial blood sample on the summit itself was too dangerous and that attempting to erect our light weight shelter would no doubt end in disaster. After about forty minutes on the summit we descended as far as ‘The Balcony’ (8475m) where conditions were more suitable for taking blood.
Within the shelter of our simple tent we were able to remove our big mittens and expose the femoral artery of each subject in order to take a small sample of blood. Taking arterial blood at such an altitude is no easy task and we were glad of the practice we’d had on other large mountains. The samples were carried by one of our nimblest Sherpas (Pasang Tenzing Sherpa) to the Camp 2 laboratory some 2000m below in a staggering two hours.
Successful analysis in the blood gas machine at Camp 2 revealed shockingly low levels of oxygen in the blood of the climbers studied. These results are the highest arterial blood gases ever obtained and go a long way to show just how adaptable the human body can be to extreme hypoxia.
So there ended our endeavours to explore the physiology of the human body when pushed to extremes. We safely descended the mountain and returned to base camp a number of days later. By that time nearly all 200 of the trekkers had passed through the laboratories and completed their testing. All that remains now is for the investigators to test one another for one last time at base camp before trekking back to Lukla for the somewhat hair-raising flight to Kathmandu.
Dan Martin
Government warning highlights global problem.
A man with a strain of tuberculosis that is immune to nearly all drugs travelled from Atlanta to Paris to Prague to Montreal this month before the authorities caught up with him and got him into isolation.
Read the story here.
Giant black holes create mystery by not flying out of galaxies.
Theorists predicted it would be one of the most dramatic events in the Universe: two black holes merging in a distant galaxy and then flying out of that galaxy, releasing the energy of tens of millions of Suns.
Read the story here.
Pure lump of silicon-28 could help to redefine the kilogram.
Researchers are a step closer to redefining the kilogram, thanks to the creation of the purest chunk of crystalline silicon-28 yet made.
Read the story here.
Planets around commonest stars in our Galaxy might be warm and safe.
The most common type of star in the Galaxy may be more hospitable to life than was previously believed, say astronomers who have calculated how much radiation planets orbiting such stars would receive.
Read the story here.
Discovery adds to understanding of individuals' susceptibility.
A large-scale genetic study has identified four new genes that significantly affect a woman's risk of developing breast cancer.
Read more here.
Satellites help to pinpoint highest-risk earthquake zones.
Global positioning systems (GPS) could help identify the places most at risk of devastating earthquakes, say researchers who have used the technology to identify high-hazard ‘locked zones’ that can spawn giant quakes.
Read more here
How do you prevent valuable collectors' items from degrading?
Many environmentalists would tell you that plastics, such as those that litter our oceans and landscapes, last for ever. But ask the collectors and museum curators who have gathered at London's Victoria and Albert Museum this week, and they will say the opposite.
Read all about it here
Mouth shapes are enough to distinguish one language from another.
Even before they begin to speak themselves, a young baby can tell when you're speaking a different language just by looking at your face.
Read more here
Soya beans and cotton could be treated with alternative herbicide.
Researchers have created what could be the next generation of transgenic crops by inserting a gene for herbicide resistance from a bacterium into plants. The new crops could help to combat the spread of resistance to other commonly used herbicides.
Read more here
The Everest team, including Dan Martin who has been writing a diary of the trip for Nature, have made it successfully to the summit:
The Caudwell Xtreme Everest Team are pleased to announce that Mike Grocott, Sundeep Dhillon, Chris Imray, Dan Martin, Nigel Hart, and Dave Rasmussen summitted Everest from the south side at 06.30 this morning (Nepal time). They were joined by Pema Tharki Sherpa, Mingma Tsiri Sherpa, Thundu Sherpa, Pasang Tenzing Sherpa (all brothers), Tshering Pemba Sherpa, Pema Chhiring Sherpa, Tashi Sherpa, Pasang Nuru Sherpa, Ongda Gyalzen Sherpa, and Dendi Sherpa. They are all now resting at Camp Four at the South Col.
Michael Brown, Vijay Ahuja, and Maryam Khosravi are also at Camp Four, and they have been joined by Paul Gunning, Roger McMorrow, Mick O’Dwyer, Jeremy Windsor, and Andre Vercueil. These five climbers moved up from Camp Three half way up the Lhotse face today.
Denny Levett, Patrick Doyle, and Graham Hoyland have remained at Camp Two, and were instrumental in keeping communications going between the climbing team and the rest of the mountain during the summit attempt last night. They have also continued to care for an injured climber, who is awaiting evacuation to base camp.
Watch this space for more details once they've got their breath back!
This week the Nature Podcast mingles with the stars, finds out how cancers are kindled, and studies historical hurricanes.
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The spring AGU meeting this year is in Acapulco, Mexico.. It is a joint affair with nearly a dozen Latin American societies. About 2,300 scientists have registered. This makes it smaller than some of the earlier joint meetings the AGU has held in the last four years to enhance scientific outreach. Certainly not as huge as the joint meeting with European societies four years ago in Nice, France, where some 10,000 scientists attended. Security at that event was insane, due to invasion/war in Iraq. No such problems in Acapulco. Although Mexican police/army trucks cruising oceanfront boulevard watching for drug lords are almost as frequent as buses. My long walk along the coast late last night turned up nothing but great pork posole and fine cazadores tequila. To many US-named fast-food spots along the way though. But at least a trendy little tequilaria like a coffee stand. Balmy doesn´t fully describe weather. Only a 2 degrees F spread predicted, from 82 to 84, day and nite. High humidity, full clouds. It´s Chabuso (read tropical storm) season. Hopefully, that doesn´t mean an earthquake. We sit atop one of THE most active quake zones. And new research revealed at the meeting raises the spector of a strange calm before a tectonic storm. Off to 14th floor hotel room. Hoping the building engineers did their job right decades ago when with this slightly frayed resort sprouted high-rises.
When you win a Nobel prize, you become much in demand. Eric Sorensen takes a look at how laureates decide which worthy causes to lend their name to.
Half a century has passed since chemist Linus Pauling spearheaded one of the biggest petitions ever in science. More than 11,000 scientists, including 36 of Pauling's fellow Nobel laureates, signed on to call for the "ultimate effective abolition of nuclear weapons". The petition led to the first international attempt to control nuclear weapons — the Partial Test Ban Treaty. And on the same day in 1963 that the treaty went into effect, the Norwegian Nobel Committee announced that Pauling would receive the peace prize to go with his 1954 Nobel Prize in Chemistry.
Scientific petitions graced by laureates have become common tools of activism — clamouring to free the unjustly imprisoned and cure a myriad of perceived ills, from drug laws to inadequate research funding to nuclear proliferation. Having a Nobel laureate's name on a petition almost guarantees it extra attention: in a newspaper story's first paragraph, if not its headline.
Read more here
Forecasters predict above-average spate of Atlantic storms.
US government scientists have released their latest prediction for how many hurricanes to expect in the Atlantic Ocean this summer. And the forecast contains a stark warning: don’t let the relative calm of last year lull you into a false sense of security.
Read more here
Cyber-attacks in the Baltic raise difficult questions about the threat of state-sponsored information warfare, says Philip Ball.
Is Estonia at war? Even the country’s leaders don’t seem sure. Over the past several weeks the Baltic nation has suffered serious attacks, but no one has been killed and it isn’t even clear who the enemy is.
Read more here
Fossil calls into question the purpose of the first feathers
Feathery dinosaurs might not have been as common as experts thought, according to researchers who analysed a fossil of a creature previously thought to have feathers, and found instead that it was bald.
Read the story here
Common pigment may allow bizarre feeding habits.
From plastic to asbestos, cardboard to jet fuel, fungi will eat just about anything. Now researchers have found another dish in the fungal diet: radiation. Not radioactive compounds, which have long been known to be on the menu — radiation itself.
Read more here
New census highlights threatened status of many species.
One-sixth of Europe’s mammal species are threatened with extinction, according to a comprehensive survey by the World Conservation Union (IUCN). Unless the trend is reversed, conservationists fear that the European Union will not be able to meet its self-imposed target of halting biodiversity loss by 2010.
Read more here
Little blue pill might help people shift their body clock forwards.
It's a safe bet that most people who take sildenafil — better known under its commercial name, Viagra — aren't looking for a good night's rest. But it turns out that the 'little blue pill' commonly used to treat erectile dysfunction is also good for relieving some forms of jetlag. Well, at least in hamsters.
Join Rex Dalton at the American Geophysical Union meeting in Acapulco from 22-25 May. He'll be blogging here for Nature.
Once beyond the event horizon, what should you do?
So there you are: you discover that your spaceship has inadvertently slipped across the event horizon of a black hole, and now there's no escape from being squeezed to oblivion by gravity. The only question is how you can maximize the time you have left. What do you do?
Pharmed food crop approved for growth despite controversy.
Rice modified to express proteins often found in breast milk will be planted in Kansas. The go-ahead for the planting came on 16 May from the United States Department of Agriculture (USDA).
An unsteered ship may have delivered crop to Polynesia.
How did the South American sweet potato wind up in Polynesia? New research suggests that the crop could have simply floated there on a ship.
Supreme Court refuses appeal to block human stem-cell research.
California's human stem-cell programme is now free of legal challenges, clearing the way for $3 billion in funding to flow towards researchers.
Windy waters may mean less greenhouse gas is stored at sea.
The ability of the Southern Ocean to remove carbon dioxide from the atmosphere is being eroded by climate change, say environmental researchers. If the trend continues, then the ability of this ‘carbon sink’ to deal with humankind’s greenhouse emissions will be impaired.
Read more here
As a second mosquito species is sequenced, news@nature.com looks back to see what these genomes do for science.
The ethical debate about a vaccine for a sexually transmitted disease has been premature, says Apoorva Mandavilli; we don't even know how well it works.
Here's a good lesson: before you start pushing for a controversial vaccine to be made compulsory, best wait for the research — and I mean all the research — to come up with results.
This week the Nature Podcast peers at hotspots on Saturn’s moon, finds out that herpes can sometimes be helpful, and explores a ‘hair-raising’ tale.
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Research on mice raises hopes for regrowing hair.
Skin may have the capacity to regenerate lost hair follicles from within, according to a new discovery that could yield better treatments for baldness or abnormal hair growth. Researchers in the United States have found that, when skin is wounded, epidermal cells can respond by assuming the properties of stem cells that generate hair follicles and growing new hair.
Read more here
From the massive wealth of Bill Gates to the pennies of the masses, the private money given to scientific research and development has a huge impact. Nature takes a look at who is giving what, and the effects it has.
See our online special.
Viral infections give mice an immunity boost.
The herpesviruses bring untold suffering, but may not be all bad. Chronic latent infection with specific viral strains protects mice against some bacterial infections, a Nature study reveals this week.
Study shows how micro molecules interfere with gene expression.
Tiny fragments of RNA called microRNAs are known to interfere with gene expression, but how? A new study hints that they get involved right at the start of the game — they seem to prevent protein production before it even starts.
African proposal to ban all trade may not be the answer.
Sophisticated smuggling syndicates are driving a soaring trade in illegal ivory from Africa to Asia, according to a new report.
But having a mutated p53 gene may help ward off tumours after chemotherapy.
A key gene that helps the body to avoid cancer may sometimes hinder cancer treatment, suggest scientists today. On the flipside, the mutated version of the gene, which usually cannot protect against cancer, might work to a patient's advantage during therapy.
Neuroscience can't show us the source of free will, says Philip Ball, because it's not a scientific concept.
Gluing a fly's head to a wire and watching it trying to fly sounds more like the sort of experiment a naughty schoolboy would conduct than one that turns out to have philosophical and legal implications.
A distant cluster of galaxies contains a hoop of the elusive dark stuff.
A ghostly ripple spotted within a cluster of galaxies 5 billion light years away supplies further evidence that the mysterious substance known as dark matter really exists.
Andromeda will collide with the Milky Way sooner than thought, and may steal the Sun.
Our Milky Way galaxy is headed for a sedate collision with its neighbour, the Andromeda galaxy, billions of years earlier than was previously thought. The earlier date means that the Sun will still be alive when the two collide; and a new computer simulation shows what could happen to our star.
Third inquiry into bubble fusion is underway.
Purdue University has set up a third panel to look at allegations of research misconduct against nuclear engineer Rusi Taleyarkhan. The existence of the latest inquiry emerged when a congressional committee wrote to the university questioning the thoroughness of its earlier review. Now Purdue, based in West Lafayette, Indiana, faces an uphill task in convincing the wider scientific community that it is mounting a serious investigative effort, critics say.
Latest study suggests that milky tea is just as good for you
Here's a ray of hope for milky-tea drinkers: new research shows that the quaint British custom of adding milk doesn't ruin the beneficial properties of the traditional drink.
Read the story here
A natural sand-bridge made his defeat of Tyre easier.
Historians need not be quite so impressed by Alexander the Great's defeat of the island of Tyre in 332BC. Geological studies of the region show that Alexander's army had help reaching the island, in the form of a natural land-bridge lying just a metre or two below the water's surface.
Project aims to bring high-tech device to developing world.
A consortium of UK universities hopes to bring affordable domestic appliances to rural areas of developing countries by developing a device that acts as a refrigerator, cooker and power generator all in one, powered by locally available biomass fuels such as wood.
Members of the Caudwell Xtreme Everest expedition, testing human adaptation to hypoxia on the roof of the world, write a diary blog for Nature from 30 March, 2007.
Having completed our week long research programme at Camp 2 on Mount Everest (6,400m) the climbers have decided to come down low for some well earned rest. The remainder of the Caudwell Xtreme Everest (CXE) investigators continue to work testing all the trekkers that come through the four laboratories in Nepal (Kathmandu, Namche Bazaar, Pheriche and Everest Base Camp).
We are over half way through testing the trekking groups now and data collection has gone extremely well thanks to the effort of the teams at each laboratory. Altitude illness has been minimal on account of the slow ascent profile the trekkers take which means we have been able to test nearly every subject on the cardiopulmonary exercise (CPX) system. The volume of data from the 200 volunteer trekkers and our group of 24 investigator/subjects will be vast. I foresee a busy time ahead analysing the data, a task that will no doubt take a number of years to complete.
Why descend to low altitude in order to rest? Climbing up and down the mountain has taken its toll on many of the team. Some of the men in the group have lost over ten kilograms in the space of six weeks and as a consequence are beginning to feel weak.
High altitude weight loss is a well documented but poorly understood phenomenon. It is one of the consequences of high altitude travel which we shall be investigating whilst here. Above 5,000m despite what seems like an adequate diet people begin to lose weight at an alarming rate. It seems to affect men more than women, and perhaps most disturbingly the weight loss is due not only to fat loss but muscle wasting.
Loss of muscle mass is the last thing one needs when trying to climb the highest mountain in the world. So we have walked down the valley to a village called Dingboche at an altitude a little over 4,000m in order to relax and try and put some weight back on! It certainly is a strange sight in the lodge: a group of undernourished bearded climbers trying to eat as much as they possibly can before returning to base camp! This will be our last chance to rest before the final push up the mountain so we are trying to make the most of it.
When we return to the mountain we have one more laboratory to set up – the South Col laboratory. At 8,000m this will be the highest laboratory in the world. Although on previous expeditions we have taken blood at higher altitudes we have never attempted to set up a powered laboratory and investigate subjects as they pass through on their way to the summit. We plan to perform CPX, spirometry (lung function), transcranial Doppler (ultrasound of blood flow to the brain), sidestream darkfield imaging (a method of imaging blood flow under the tongue) and arterial blood gas analysis whilst there. If successful this will be the highest that any of these techniques have been performed and will provide unique data about human physiology at extreme altitudes.
Hopefully we will all muster the enthusiasm to return to base camp soon and the weather improves sufficiently for us to begin our journey towards the summit.
Dan Martin
Link shows storms in Africa can cause havoc in the United States.
What creates an Atlantic hurricane? The most devastating ones are spurred by intense thunderstorms in the Ethiopian highlands, according to new research.
Astronomers find a star that's 13.2 billion years old
read the story here
Study shows vaporizer delivers marijuana 'safely and effectively'.
Vaporizing cannabis leaves instead of burning them can release the drug's active ingredient just as effectively — while avoiding the harmful toxins inhaled through smoking the drug, according to a pilot study.
Videos reveal how bats turn quickly and get lift.
Bats and birds use their wing-flapping powers differently, a video study of the night flyers reveals. Bats leave a more complicated pattern of swirling vortices in their wake, and work harder on their upstroke than birds. This, the researchers say, may be the secret to their super-maneuverability. And it means that they fly a bit like a bee.
read the story here
Computer program should re-assemble notes from the East German Stasi.
A research team in Germany has developed a computer-software system to piece together some 45 million pages of secret police files ripped into 600 million pieces. The files were torn up nearly 18 years ago by panicking agents of communist East Germany's dreaded State Security Service (Stasi).
Online effort aims to bring together biodiversity knowledge.
An effort to collate information on nearly 2 million species of animals, plants and other forms of life into a single online database launches today.
Monodelphis domestica bags the first marsupial genome.
Such a small creature for so great an honour: the grey short-tailed opossum is the first marsupial to have its genome fully sequenced, joining a menagerie of other mammals including the mouse, rat, chimpanzee and, of course, human.
Tribeca Film Festival showcases upcoming sci-fi and biopics.
New York's Tribeca Film Festival wrapped up last weekend, after providing an eyeful of science-based films coming soon (maybe) to a theatre near you; and an earful of how Hollywood sees the role of science changing in the movies.
This week on the Nature Podcast Chris Smith finds out how lithium can be a superconductor, issues the first weather report from extra-solar planet HD 189733b, and delves into the genome of the first marsupial to be sequenced, the opossum.
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The hot, the fat and the molten
The past few weeks have been feverishly active for planetary scientists — record-breaking results have popped out in all directions.
read the story here
British activists arrested, but rabbits replaced with in vitro tests in Europe.
Police last week cracked down on animal-rights activists across Britain, Belgium and the Netherlands. Many of the 32 people arrested were connected to the campaign against Cambridgeshire-based Huntingdon Life Sciences, which has been a focus of attacks in recent years along with Oxford University's new biomedical laboratory. Nine people have been charged with various offences, with most of the rest being released on bail.
How do you search for something when you don't know what you're looking for?
Most physicists at Illinois-based Fermilab, home to the world's most powerful particle collider, share a dream. They hope against hope that the Tevatron will find the long-sought Higgs particle before the much more powerful Large Hadron Collider (LHC) at CERN — the European particle-physics laboratory outside Geneva, Switzerland — comes along in a year or so and eats their lunch. Bruce Knuteson, though, has a fear. What if the LHC finds something even more exotic than the Higgs —and the tell-tale traces of that novelty turn out to have been lurking, unrecognized, in Fermilab's data for years?
Pakistan places advertisements regarding 'misplaced' isotopes.
A Pakistani public information campaign about what to do if you stumble across stray radioactive material is raising hairs on the necks of Western arms control experts.
Bright supernova reveals secrets of star death.
Astronomers have witnessed the brightest stellar explosion ever recorded — a supernova called SN 2006gy.
Patent for technology to fire genes into soy seeds thrown out.
The European Patent Office (EPO) has revoked a patent owned by global agricultural giant Monsanto for the genetic modification (GM) of soybeans, saying the technique it approved 13 years ago lacked "novelty".
Game ranks researchers by proximity to field's founder.
"What's your Abel number?" was the big question being asked by pharmacologists this week at the Experimental Biology meeting in Washington, DC.
Creepy crawlies are the latest weapon in the anti-MRSA arsenal.
The drug-resistant bug MRSA has a new adversary — the maggot. Researchers in Manchester, UK, have just won a grant to compare maggots with other more hi-tech treatments for people with diabetes who suffer from infected feet.
Read the story here
International report sets out costs of bringing down global emissions.
Bringing greenhouse gas emissions under control looks to be both achievable and affordable, on the basis of the most recent report of the Intergovernmental Panel on Climate Change (IPCC).
Bangkok summit sees tension over plans for emissions cuts.
Climate experts at an international meeting in Bangkok, Thailand, have spent the week locked in negotiations about how to tackle the rising tide of greenhouse gases. They are scheduled to publish a summary report on Friday morning that will advise governments on how best to curb emissions and keep levels of carbon dioxide in the atmosphere in check.
Road map points the way to untouched wilderness.
A new type of road map, which highlights roadless areas by showing them as mountain peaks, could prove a valuable aid to conservationists — or even to hikers searching for remote corners of the globe.
Bacterial baths help amphibians fight off fungus.
Planting bacteria on frogs' skin might help to save amphibians from their global decline, hints new research. The work shows that frog probiotics can help to fight off a lethal fungus.
Bangkok summit sees tension over plans for emissions cuts.
Climate experts at an international meeting in Bangkok, Thailand, have spent the week locked in negotiations about how to tackle the rising tide of greenhouse gases. They are scheduled to publish a summary report on Friday morning that will advise governments on how best to curb emissions and keep levels of carbon dioxide in the atmosphere in check.
Read more here
Members of the Caudwell Xtreme Everest expedition, testing human adaptation to hypoxia on the roof of the world, write a diary blog for Nature from 30 March, 2007.
A number of the Caudwell Xtreme Everest (CXE) Investigators have just safely returned from a week of working at camp 2 on Mount Everest, in the Western Cwm – 6,400m above sea level. Whilst there we managed to perform a large number of studies under very difficult conditions. The temperature fluctuations experienced at base camp were magnified and now we had to worry about added dangers of heavy snowfall and avalanche.
We took venous and arterial blood to look at haemoglobin, haematocrit and gas partial pressures. We were genuinely shocked by the partial pressure of oxygen in our arterial blood at this altitude; values lower than I’d ever seen during my years working with critically ill patients on intensive care units. Yet we were still able to function normally and carry out complex tasks, including stripping and rebuilding the blood gas machine on site!
Many studies were completed at Camp 2, such as the highest ever breath-by-breath cardiopulmonary exercise (CPX) tests, neuropsychological tests, body composition and nutritional studies, brain Doppler, sidestream darkfield examination of the sublingual microcirculation, spirometry and a comparison of different supplemental oxygen circuits during exercise. By the end of the week the entire team was exhausted and ready to come back to base camp for a well earned rest. Unfortunately to get down to base camp meant once again picking our way through the Khumbu icefall. In the week that we had been up at Camp 2 huge sections of the icefall had collapsed which meant the Sherpas had to seek a new route through. A sobering reminder that everything beneath us is slowly moving downhill and that at any moment a big movement could either engulf or crush us as we attempt to scale this giant mountain.
Last time I explained our primary hypothesis which is centred on a change in oxygen utilisation, or efficiency, as a result of exposure to hypoxia. There are many other aspects to the research on this expedition and hopefully I can give you a taster of these now.
Although concentrating on oxygen utilisation, there are still components of the process of oxygen delivery which interest us. We are looking at the way in which systemic oxygen delivery changes during exercise at altitude using a pulse contour analysis device (LiDCO). Simultaneously we can look at regional blood flow, in particular that of the gut by using the somewhat unpopular technique of gastric tonometry. Our willing volunteers (only CXE investigators for this study!) have a special naso-gastric tube inserted which measures gastric perfusion as they perform exercise on a CPX bicycle. As subjects exercise on the CPX bicycle we will also use near infra-red spectroscopy (NIRS) to measure the amount of oxygen in their muscles as the exercise load increases. To complete our investigation of oxygen delivery at altitude we move from systemic, through regional down to microvascular blood flow. Using a technology based on orthogonal polarization spectral (OPS) imaging we are able to easily visualise the sublingual microcirculation at altitude. Using the a side-stream darkfield (SDF) camera we can illuminate erythrocytes as they pass through the microcirculation and record their passage to analyse flow characteristics once back at sea level. The microcirculation forms a vital link between the systemic circulation and cellular tissue. Without a properly functioning microcirculation the delivery of oxygen from the erythrocytes to cells may be impeded.
We have a large program to investigate the performance of the neurological system at altitude. In both the investigator team and trekking group we shall be using a number of techniques to look at changes in cerebral function as altitude increases. This may help us to understand the physiology of the hypoxic brain following severe traumatic head injury, a sadly common presentation to intensive care units across the globe. Each subject will undergo a number of specially selected neuro-cognitive tests. These consist of almost an hour of written, oral and dexterity tests designed to tease out subtle changes in cognition associated with hypoxia. We shall also be using techniques to study pupil reaction time and scanning eye movements known as saccades. In a similar manner to the study of muscle oxygenation we will use NIRS to look at brain oxygen levels as subjects exercise. Transcranial Doppler is also being used to look at blood flow within the brain. In a small sub-group of subjects, potential changes in brain structure are being explored using magnetic resonance imaging.
Maintenance of body mass at altitude is well known to any of you who have ventured to these heights; people lose weight in astonishing amounts. This phenomenon is also seen in critically ill patients on intensive care. We are looking into why such incredible weight loss occurs at altitude by studying body composition and dietary absorption and excretion.
There are other studies looking at changes in taste and smell at altitude, how to relieve the distressing problem of breathing related sleep disturbance at altitude, changes in electrocardiogram tracings and the development of a novel supplemental oxygen re-breathing circuit. The circuit will be tested by climbers on the mountain and is based on re-breathing technology used by fire-fighters and deep sea divers in their breathing circuits. If the re-breathing circuit proves to be beneficial to climbers deprived of oxygen high on Everest its benefits may well be transferable to those individuals dependent on long term oxygen therapy due to lung disease back at home.
Hopefully you now have some idea of the vast scale of the Caudwell Xtreme Everest project and the enormous task that it has been to coordinate so many studies in such an inhospitable environment. Our plan for the next week is to relax at base camp before preparing to once again ascend Everest to carry on the scientific program right to the summit of the mountain.
Dan Martin
Molecular geneticists riff with strings of protein-coding DNA.
Imagine humming along to horse haemoglobin or tapping your toes to transcription factors. Now you can, thanks to a pair of molecular biologists who have developed a way to turn such proteins into music.
This week the Nature Podcast finds out about the lazier cousins of earthquakes, what the brain does with its free time, and how dieting worms live longer.
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Bacterial proteins can set up a sensitivity to metal in mice.
Allergic reactions to metal are on the rise, although no one knows why. Now research suggests that bacterial infections experienced while wearing metal objects may be responsible.
Members of the Caudwell Xtreme Everest expedition, testing human adaptation to hypoxia on the roof of the world, write a diary blog for Nature from 30 March, 2007.
We have now been in Nepal for a month and are beginning to set up one of our laboratories high on Mount Everest. This laboratory is situated at Camp 2 (6,800m) in the Western Cwm and will be home to the investigators of the Caudwell Xtreme Everest project for the following week. But before I set off to great heights, here’s some more explanation of what we’re trying to find out.
As lowland residents travel to high altitude they are exposed to increasing levels of hypoxia. The physiological response to this insult is known as acclimatisation and our current understanding of it consists of a number of processes which together increase systemic oxygen delivery. Changes such as hyperventilation, tachycardia [fast heart rate], increased cardiac output and increased red blood cell mass all ensure that as much oxygen as possible is extracted from the rarefied air and passed on to the metabolising tissues which require it. We have known about this adaptive process for many years and its subtleties are detailed in many well respected texts. But what if this increase in oxygen delivery is not the whole story? Perhaps there is more to the process of acclimatisation than we had previously thought.
Certainly in the world of high altitude medicine and physiology we are aware that some individuals are clearly better performers than others in the hypoxic environment found towards the summits of the world’s highest peaks. But studies so far have been unable to demonstrate a clear physiological advantage in such individuals. In fact their physiology is remarkably normal, showing no signs of being more capable of delivering oxygen than those who fair less well at altitude. So how is it that some individuals perform better than others in the face of similar degrees of oxygen delivery?
It is possible that there are advantageous changes in oxygen utilisation occurring within individuals who perform better in a hypoxic environment. More specifically, at the level of the mitochondria, enzymatic changes could be occurring which allow the cells to produces energy more efficiently under low oxygen conditions.
So how do we intend to explore this hypothesis? We have thought long and hard about our methodology and believe that if differences in oxygen utilisation exist between individuals, our study will detect them.
We have invited a group of two hundred healthy individuals to cycle on a cardiopulmonary exercise testing (CPX) system at sea level. They performed exercise at steady state, sub-anaerobic threshold workloads whilst we measured oxygen consumption and carbon dioxide production on a breath-by-breath basis. From this we can calculate oxygen consumption at each of the selected workloads. In small groups these subjects will then trek to Everest base camp (5,300m), repeating the test a total of four more times at increasing altitudes. By comparing oxygen consumption at each of the altitudes we hope to see changes in oxygen consumption and thus efficiency as they ascend. It would be fair to conclude that any change in oxygen consumption would be due to increasing hypoxia.
What advantage would this cellular hypoxic efficiency have for an individual? In evolutionary terms it is difficult to suggest a reason. High altitude mountaineering is hardly a beneficial characteristic to pass on to the next generation and survival of critical illness is a vastly complex process frequently modified by medical intervention. Suffice to say, genetics is clearly a governing factor in the ability of mitochondria to modify their enzymatic processes in the face of hypoxia. We therefore intend to analyse a number of genetic loci known to be involved in human performance and hypoxic signalling. This will enable us to correlate changes in metabolic efficiency with specific genetic polymorphisms in our subjects.
We shall begin our ascent into the Western Cwm tomorrow and when we return I shall tell you how our high altitude exploits went. After a rest of a week or so we shall return to the mountain, this time aiming for the summit.
Dan Martin
Like mole rats, hominins may have had a diet rich in bulbs and tubers.
Palaeontologists have turned to an unlikely source in a bid to uncover the dietary habits of some of humanity’s oldest ancestors. They have studied the teeth of mole rats found in South Africa to bolster the theory that prehistoric hominins may have eaten underground bulbs and tubers, rather than meat or grass.
Read more here
Investigation vindicates but also criticises researchers
Claims that a wolf has been successfully cloned are solid, an internal university investigation has found.
read the story here
Study adds to evidence of a physical basis for 'Gulf War syndrome'.
Regions of the brain important for thinking and memory may have shrunk in some veterans of the first Gulf War, according to a new study. The decline is at its worst in veterans who report more symptoms of what is commonly called 'Gulf War syndrome', the mysterious condition that has afflicted as many as one in seven veterans from the 1990-1991 war.
