Shell Tough Ceramics and Sharing Vaccines

08 December 2008
Presented by Ben Valsler.

PAUA-SHELLS

Blackfoot Paua, photo taken in New Zealand

Share

In this week's NewsFlash, how we hear how seashells have inspired tough new ceramics, uncover a signal that links food to body fat, discover how Sea Turtles thrive on untouched beaches and hear how a fraction of a dose of vaccine may be enough to prevent an epidemic.

In this episode

Inspired by nature

Scientists this week have unveiled a brand new material that was inspired by nature and is thought to be the toughest, strongest ceramic-type material that has ever been made.

Nacre - a calcium carbonate structureThis new invention was announced this week in the journal Science, by Robert Richie and his colleagues from the Lawrence Berkley National Laboratory in California in the United States.

Their inspiration came from mother of pearl or nacre, the iridescent, shiny covering found on the inside of seashells, it's also the same stuff that pearls are made from.

Essentially, mother of pearl is made from calcium carbonate, which in itself doesn't seem to be all that remarkable. But it is the arrangement of strong but brittle layers of calcium carbonate, interspersed with slippery organic layers that act like a lubricant and ultimately makes nacre three times tougher and less likely to shatter than normal calcium carbonate. These layers are also the key to the beautiful lustre of mother of pearl and pearls.

And while scientists have for a while known the secret to these incredibly tough natural materials, until now, no-one has been able to artificially recreate them except in just very thin sheets of material.

This new material isn't actually made form calcium carbonate, but from a mixture of aluminium oxide and plain old water. By mixing the two together then carefully freezing the mixture, the researchers were able to encourage the aluminium oxide to form sheets. Freeze drying the mixture then gets rid of the water leaving a scaffold of aluminium oxide into which a polymer is then added.

This allowed Richie and his team to mimic the same interspersed layers that are found inside mother of pearl which are the secret to creating a material that is extremely strong but even if cracks start to form, they don't get bigger.

The team think they should be able to further refine their super-tough ceramics, but making the structures even finer and closer to the actual structure of natural mother of pearl.

The Pathway to Obesity

Scientists have found another chemical involved in obesity - one that could hold promise for preventing diabetes.

Obesity in the 17th CenturyWriting in the journal Cell Metabolism, the researchers (and there's lots of them - from Louisiana state university, University of Alabama at Birmingham, Columbia University Medical Centre, and Cambridge University here in the UK), have identified the role of a protein called adropin, which plays an important role in digestion - regulating a group of genes which affect how energy is stored, including the production of lipids (fats) from carbohydrates that we eat.

Adropin is coded for by a gene called Energy Homeostasis Associated (Enho) - a gene expressed in the in liver and in the brain.  Expression of the gene itself if regulated by the amount of fat in the diet - mice on a very high fat diet showed a rapid increase in adropin, while fasting mice showed a reduction.

This makes adropin one of the first factors shown to be directly related to the amount of fat in our diets, but there's a further twist to this tale.  Obese mice, whether obese because of diet or genetics, don't produce adropin normally, but obese mice given extra adropin show less fat in their livers and respond better to insulin.  These obese mice do eventually lose weight but the benefits, such as reduced liver fat, can be seen long before the weight is lost.

As the gene for adropin is expressed in both the liver and the brain, it could well have some effect on the brain that we do not yet understand, so we still have a long way to go and this certainly isn't a quick fix for obesity or the associated diseases.  However, as adropin seems to be instrumental in the homeostasis of glucose and lipids, it's certainly a candidate for further research.

Turtles and tourism

Back into the marine world once more, with a story this week that has provided the first robust evidence that sea turtles are more successful at producing young when females lay their eggs on beaches that are untouched by human hand.

TurtleThat's according to David Pike from the University of Sydney in Australia who published his study this week in the journal Biology Letters.

They may spend the majority of their lives in the ocean, but female sea turtles are tied to the land and have to haul themselves out on beaches to lay their eggs.

What Pike did was to hunt through hundreds of other studies published by people who have gone out and counted how many turtle eggs hatch on different types of beach - both those were people are present, with coastal developments like hotels and resorts, and beaches where there is no permanent human presence.

And what he found may not come as much of a surprise: for both the magnificent loggerhead turtles, and green turtles, on average around 12 to 16% more eggs hatched on undisturbed beaches compared to those on beaches with human developments on them.

That may not sound like a lot, but this is likely to be an important difference for turtles that face a host of different threats to their survival, including being accidentally caught at sea in trawling nets and because turtles often mistake plastic bags for one of their favourite food: jellyfish.

It is not clear exactly why the hatching success rate is so much lower on developed beaches, but it is likely to be a combination of factors including trampling and physical disturbance by people and various forms of pollution.

This study has shown how crucial it is to protect nesting beaches that are currently not disturbed by coastal developments because there are the areas where many turtles are being born, and it is the young turtles that will determine the future of these wonderful species.

Lower dose vaccine does the job

When an epidemic looms, governments should stockpile vaccines.  That's a no brainer, but what if you have little warning, or the cost or development times are prohibitive?  Research in PloS Neglected Tropical Diseases suggests that a mere fraction of a vaccine may give enough short term immunity to stop an epidemic in it's tracks.

Line for meningitis vaccinations in Arua, Uganda
Line for meningitis vaccinations in Arua, Uganda © Sanjoy Ghosh

Looking at meningitis outbreaks in Sub-Saharan Africa, Phillipe Guerin and colleagues from institutions in Norway, Uganda and Manchester looked at the immune response of 750 healthy volunteers when they were given either a full dose of meningitis vaccine, one fifth of a dose or just one tenth.  They measured immune response by looking at something called serum bactericidal activity, which does exactly what it says on the tin - a measure of how effective a blood sample is at killing bacteria.  They took blood samples immediately before, then four weeks after vaccination, and tested them against 4 serotypes, subgroups of meningitis, called A, C, Y and W135.

So how did the partial doses fair against a full dose?  Well, of the 4 serotypes, a tenth dose of vaccine was as good as a full dose for types Y and W135.  One fifth of the vaccine dose was enough for group A, but only the full vaccine dose gave an adequate serum bactericidal activity for group C.

Clearly, we shouldn't be stretching our resources beyond our limits, but in times of emergency, controlling vaccine dose in this way could allow us to protect many more people in the time available, and could be what we need to stop an epidemic in it's tracks.

Comments

Add a comment