The Darwin Festival

07 August 2009

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This week we bring you the highlights from the 2009 Darwin Festival to meet the man behind the Human Genome project as well as bring you the rap guide to Evolution! We also find out about a new, efficient technique to diagnose Tuberculosis and brave the tattoo parlour for Question of the week!

In this episode

Bad news for malaria

Scientists have uncovered new insight into malaria, the deadly disease that affects around 500 million people every year. Sub Saharan African suffers the worst, with an annual death toll of 1 million people annually, mostly children aged between six months and three years.

A newborn babyIt was that statistic of the age-related risk that was the focus of this study in the journal PLoS Medicine, by Christopher King from Case Western Reserve University and his colleagues.

The research team followed up 586 babies born in Kenya from their birth up until their 3rd birthday.  They took samples of umbilical cord blood form the babies and also some blood from the mothers.

As we might expect, some of the mothers were infected with malaria at the time of delivery.  King and the team suspected that this would expose the baby to products made by the malaria parasites while still in the womb, and cause the babies' immune system to develop tolerance to malaria - a process by which the immune system learns what it should ignore when we are first born and what it should launch an attack on.

To test their ideas, they mixed malaria antigens with white blood cells from some of the babies with infected mothers and found that the cells reacted only very weakly to the malarial signal.

Babies whose mothers weren't infected, showed a very strong reaction and pumped out lots of inflammatory hormones.

This suggests that mothers that are infected with malaria pass trigger a tolerance to the malaria in their babies which means they ignore it rather than attack it.

Babies receive antibodies from their mother, which makes them protected from malaria for the first 6 months of life.  After that, the baby because vulnerable.  But if their immune system thinks that malaria is friend rather than foe, then the vaccines will have to tackle this re-programming error if they are going to work.

Deceptive orchids smell like bees

Orchids living on Hainan Island in China have evolved to smell like upset bees.

That might sound bizarre except this particular whiff attracts hornets that come looking for a bee to take away and feed to their growing young - but instead they bumble from one deceptive orchid to another, unwittingly pollinating them.

European hornet with the remnants of a honey bee.Never trust an orchid.  In total, around one third of all the 30,000 orchids species attract pollinating insects without rewarding them with pollen or nectar. Most of them mimic the scent of other flowers that do have nectar and pollen, or they smell like potential mates, so insects come along and try to have sex with them.

This study in the journal current biology by a team from the University of Ulm in Germany has revealed for the first time that an orchid tricks pollinators into thinking they are going to find food.

The researchers spent over 120 hours watching the orchid (Dendrobium sinense) in the wild and saw that it was mostly hornets that visited them - these researchers were the first to confirm that hornets are the main pollinators for these particular orchids.  But instead of landing on the flowers and pausing for a moment as most pollinators do, they pounced on the red centre of the blooms - much like their behaviour when they attack prey.

Then, in a flight cage, hornets were just as likely to visit the orchids as an odourless European honeybee dummies injected with an extract of the flower, while ignoring dummy bees that hadn't had a spritz of flower scent.

To discover what chemical was attracting the hornets, the team then analysed the chemical makeup of the flower scent and discovered a volatile chemical called 11-eicosen-1-ol, which is the exact same compound produced by Asian and European honeybees when they are alarmed.

When hornets in the lab were given the choice of visiting an intact flower or a synthetic mix of the main chemicals identified in the scent, they had not real preference for either.  And since hornets are known to prey on honeybees, it makes perfect sense that they fly to the orchids thinking they are going to find food.

It's amazing what plants get up to, co-opting the services of animals in the most ingenious ways.

Urgent need for soil maps

Good quality, healthy soil is the stuff that underpins healthy human populations by ensuring we all have enough to eat. They also play a vital role in regulating the climate. But get it wrong, and it can spell disaster.

Soil TypesNow a group of scientists publishing in the journal Science have highlighted the urgent need to create a new map of the world's soil. Using the very latest digital, mobile and online technology to assess the state of the dirt beneath our feet may initially seem a bit excessive, but it could provide a crucial way of managing soils in particular areas, preventing their degradation and ultimately ensuring food security.

Soil maps essentially show the types and properties of soils in different areas - how much water they hold, what they are made from - all sorts of information that is vital for effective land management. Irrigation, using the limited global supplies of freshwater, is a key area where local soil type conditions needs to be taken into account. For example, in central North China Plain, more water is often pumped into fields than it can fact hold, wasting vast quantities of precious water.

The first world soil map made by the UN FAO in 1981 and it's been put to all sorts of important uses including studies of climate change, food production and land degradation. The problem is it has a very low resolution, and it doesn't include all the types of information and soil properties that we are now interested in, in the 21st century.

The 'Policy forum' paper is calling for the international collaboration to compile of a detailed, 3D soil map that would be freely available over the internet to be used by scientists, land-use planners and policy makers.

Foundations have already been laid by the Global Soil Map.net project. Started in 2006 in response to policy makers who were increasingly complaining that they couldn't get hold of useful information to answer questions like how much Carbon is locked up and emitted by soils in a particular region?

At the moment, only around 1/3 of the world's ice-free land have soil maps available at 1:1 million scale or finer. So there is a lot of information that still needs to be collected, as well as that existing information to be brought together and made readily accessible to different users, everyone from farmers to policy makers and scientists.

To make a digital soil map, in essence involves surveying particular sites for the properties of the soil and then extrapolating that to a wider area that hasn't been directly sampled - because you can't sample everywhere. Information about the physical and biological components of the soil can then be combined with geographical information on farming systems, poverty levels, crop yields, road density and all sorts of other human factors.

The hope is that once all this information has been gathered and assimilated into a single resource, it can be used to make recommendations on how soils in particular areas should best be used, and changes over time can be monitored. Ultimately, the aim is to reverse soil degradation and improve food security and people's livelihoods.

Ocean therapy

Scientists have discovered a possible new painkiller inside a type of soft coral living on Green Island, a small volcanic peak just off the coast of Taiwan.

Table CoralDr Zhi-Hong and colleagues from the National Sun Yat-Sen Univeristy in China have a paper in the British Journal of Pharmacology in which they test a compound called capnellene inside the Kenya Tree Coral (Capnella imbricata) - which look like little white trees. This molecule could prove a vital step forward for combating neuropathic pain.

People with Neuropathic pain suffer from intense pain from a stimulus that should normally only cause mild discomfort, like a cold draft. Some people even feel pain with no stimulus at all and it's a condition that may affect as much as 1 in 100 people in the UK alone.  It can be triggered by nerve damage associated with diabetes and standard pain killers like aspirin are little help.

Inflammation of the nervous system plays an important  role in causing neuropathic pain, by activating the cells that surround nerve cells, called microglia and astrocytes, and when they are active they magnify pain signals travelling along the nerves making the pain sensation more intense.

Capnellene was originally discovered in 1974 but only recently scientists began to realise how useful it might be.  The molecule has a very different structure to other painkillers.

The research team tested out capnellene both on isolated nerve cells and also on laboratory rats, and found that it reduced pain-related activities in nerve cells and the rats that suffer from neuropathic pain showed fewer pain responses when they were given doses of the compound.

It may seem strange that a coral would have developed a pain killing chemical,  but life on a coral reef is tough and competitive, with so many species living in close proximity, and many of them have evolved complex chemical defences to help give them the upper hand.  It just happens that some of those active chemicals have affects on other types of animal.

It's early days, but this discovery does offer longterm hope for sufferers of neuropathic pain and points the way towards a new generation of pain killers, that are inspired by the sea.

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