The Future of our Food

21 June 2009
Presented by Chris Smith, Helen Scales.

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This week we dig into into the science of farming and food production. We find out how transgenic plants can help us dispense with the need for chemical pesticides and how giant greenhouses at the shoreline can be home to super-efficient farms of their own. We explore the problems faced by our sweet honey bee and in Kitchen Science we do some plant modification of our own no transgenics knowledge needed, just food colouring...

In this episode

Tentacled Snake

Extraordinary snakes

There's an old wives tale that snakes hypnotise their prey, but a new study has revealed even more amazing - but real - goings-on in the snake world. Tentacled snakes (Erpaton tentaculatum) have evolved an astonishing way of tricking small fish into swimming right into their mouths. Kenneth Catania from Vanderbilt University in Tennessee in the US has uncovered how the snakes confuse the fish into swimming towards instead of away from them. The fish's reaction is so predictable that the snake aims at the spot the fish will arrive at, instead of tracking the actual movement of the fish.

These are most peculiar snakes, a type of mud snake, that have a pair of moveable tentacles on the end of their noses, the only reptiles in the world to have such a structure. They live in freshwater rivers and streams and in brackish water in Southeast Asia and when they are hunting they lie in wait motionless curling their body into a characteristic J-shape with their heads bent around in a hook.

Tentacled SnakeWhen a fish approaches, the snake lunges into action, striking out ballistically in only 15-20 milliseconds. But the fish have evolved a specialised escape mechanism that is even quicker. They detect ripples of pressure in their ears on each side of their body. When one ear picks up a pressure wave an automatic reflex signal is sent to the muscles on one side of its body, which contract causing the fish up into a C shape: scientists have called this the C-start. With their heads turned round, the fish then swims extremely rapidly away from the source of the sound, in a movement that can't be reversed once it has begun.

In his paper in the journal PNAS, Catania describes how he began watching snakes hunting in slow motion (on high speed cameras of up to 2000 frames per second) and discovered that instead of swimming away, the fish (fathead minnows) kept on swimming right into the jaws of the predator. Out of 120 trials he recorded on camera with 4 different snakes, 78% of the time the fish turned towards instead of away from the snake.

He also noticed that before the snake moves its head, it twitches a point slightly further down its body. Using a hydrophone he picked up a sound wave this motion produced.

So the snakes have co-opted the fishes' reflex escape response, deliberately making a sound comes from the other side to their heads, triggering the C-start response in the wrong direction - the fish swim towards instead of away from the snake, and all in super-quick time that a human observer can barely detect.

Even more extraordinary is Catania's discovery that instead of aiming at the fish and tracking it's movement as it swims away - as most predators do - the tentacled snakes head directly for the spot where it expects the fish to end up if they initiated a C-start towards the head.

The next thing Catania wants to find out is whether the snakes' predictive ability is hard-wired or whether they learn it. He hopes to find some baby snakes just after they have hatched and carry out the same video analysis of their first attempts to catch their dinner.

A molecular model of a fragment of DNA

RNA-away liver tumours

Scientists have used a genetic technique to successfully treat mice with liver tumours.

DNA fragmentWriting in the current edition of the journal Cell, Ohio State University researcher Jerry Mendell and his team describe how they have used short sequences of genetic material to block the growth of cancers.

The work was based on the finding in recent years that cells regulate the activity of their genes through the use of a family of small molecules called micro RNAs (miRs).  These work by shutting off the actions of certain genes, particularly those linked to cell growth and which are normally active only when cells need to divide or in a developing embryo.  But if the production of these micro RNAs goes awry then many of these growth-associated genes can be reactivated, which is what, scientists believe, might promote the growth of tumours.

Indeed, when researchers have studied a number of different cancers they have found that many of the micro RNAs that should be present are in fact missing in the malignant cells.  This led the Ohio team to ask what would happen if they put the micro RNAs back into cancerous cells?

To find out the researchers used experimental mice with a genetic tendency to develop liver cancers. Having identified one micro RNA that was frequently missing from the malignant cells in these mice, the team inserted the genetic sequence for that micro RNA - called miR-26a - into an adeno-associated virus vector (AAV), which is effectively a viral shell that lacks the ability to reproduce.

One group of mice were given injections into a blood vessel supplying the liver of a million million particles of the virus containing miR-26a.  A second group of mice received injections with a dummy virus and were used as controls.

Three weeks later the animals were studied for signs of liver tumours.  As expected, six out of eight of the control animals all had large liver tumours, but the team found that of the ten animals given the therapeutic virus eight had very few signs of disease.  In these animals tests showed that the virus had successfully penetrated 90% of the cells in the liver, and of the two animals that did not respond the treatment appeared to have failed because the viruses did not reach the liver successfully - in other words for technical rather than biological reasons.

Clearly it is early days, and the safety of this approach still needs to be confirmed, but this discovery, the first of its kind, shows that the future treatment of cancer most likely rests with genetics, rather than just toxic drugs.

Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp.

Size does matter

Giant sperm have been found inside ancient fossil crustaceans, revealing just how long ago these enormous male sex cells evolved. The oceans 100 million years ago were full of males hotly competing with each other over who got the best mates.

OstracodPublishing in the journal Science, Renate Matzke-Karasz of the Ludwig Maximilians University in Germany lead a team of researchers who studied the internal organs of some 100 million year old ostracods - a relative of crabs and lobsters that look a little like mussels (a type of mollusc of course). They are sometimes called seed shrimp, for obvious reasons if you see one.

There are around 65,0000 species of ostracod which live in marine and freshwater.

Some of the modern-day male ostracods have extraordinarily big sperm that can be up to ten times longer than they are. Now for the first time the sperm of the ancient ostracods have been discovered using a complex imaging technique called synchrotron X-ray holotomography. This non-invasive technique, developed at the European Synchrotron Radiation Facility, allows researchers to see inside these tiny creatures that are only around 1mm in size, and compile images together on a computer into a 3D model.

The team found evidence that the ancient male ostracods has huge sperm ducts (Zenker organs) inside them, and the females - like modern ostracods - have huge internal cavities that receive the sperm after mating.

Ostracods aren't the only animals that have such enormous sperm. A more familiar creature, the fruit fly, also produce 6mm sperm - an impressive feat for a 1-2mm fly. It seems bizarre to spend so much energy making such huge sperm, but it all comes down to competition for mates.

For a male that has to compete with lots of other males to get a mate, and when females mate with many different males, one way of ensuring he passes on his genes to the next generation is by producing huge sperm. In animals like fruit flies and ostracods bigger sperm are more likely to fertilize eggs inside the female than smaller ones.

It's best not to think of an analogy of this in human beings, but this study does shed light onto the evolution is this peculiar male trait - which in ostracods probably evolved just once - and showing that is been the case that size really does matter for a very long time indeed.

Social Networking in Fish

UK scientists have discovered that some fish learn by watching the experiences of others.

3 spined sticklebackDurham University scientist Jeremy Kendal, writing in the journal Behavioural Ecology, caught 270 sticklebacks from a local river.  The fish were divided into groups.  The first group were placed in a tank with two feeders, one which dished out generous portions of blood worms and another which was more frugal.

A test revealed that the fish had learned the drill and at this point they were then confined within a 'viewing gallery' section of the tank whilst a second group of fish were introduced. 

But this time the scientists reversed the feeders so that the previously generous one was now more stingey and vice versa.  The confined 'educated' sticklebacks were then left to watch how the newly-introduced fish fared.  Afterwards they were released again and the team observed which of the two feeders they now favoured.

Incredibly, just by watching how the other fish had got on, over 75% of the observering fish had learned from the experiences of the other sticklebacks that the feeder situation had reversed.  Even more impressive was that, in a subsequent experiment, when the team adjusted the relative generosity of the feeders the observing fish only changed their behaviour if they saw the other fish doing better in the new situation than they had in the old.

This kind of learning approach, known as a 'hill climbing strategy' is probably key to helping these animals to escape from predators.

"These fish are too vulnerable to forage alone," explains Kendal, "so they have to move around in groups. They are therefore social, and by watching the outcomes of others and responding appropriately this is a sound strategy to avoid predation and maximise returns."

And regardless of the evolutionary benefits, any claims of fish having a  once-round-the-tank-memory is definitely a fish out of water, at least in the stickleback world.

Bee Cab

16:21 - The Plight of the Bumblebees

We investigate why bee numbers are falling and what effect this will have on our agriculture.

The Plight of the Bumblebees
with Bridget Nicholls, Pestival; Pat Goodwin, Wellcome Trust; Steve Benbow, the London Honey Factory

Helen -   Another issue that's been hitting the headlines lately, is that of the plight of our beloved bees.  So we sent Meera Senthilingam down to London, to The Wellcome Trust to find out what all the buzz is about.

Bee CabMeera -  This week saw the unveiling of a taxi dressed up as a bee, driving around the streets of London.  Now, why is a taxi dressed like a bee, you ask?  Well, this bee cab has been custom made to celebrate Pestival.  A festival that celebrates insect life which is taking place on London South Bank this coming September.  And the theme for this year's festival is a collapse of bee colonies around the world.  Bridget Nicholls is the festival director.

Bridget -  The key theme of this year's Pestival is bees - We're creating the Queen Elizabeth Hall we'll be turning into the Queen Bee hall and is going to be called, 'The Bee Social' and it's all about people coming together from different disciplines to discuss colony collapse and creating a critical mass.  I just think that it's very important to get urban people thinking about saving the bees because they've got balconies, they can plant flowers for urban bees.  I think we are in danger of loosing our bees and obviously, we should do something about it while we can.

Meera -  Festival Director and organizer Bridget Nicholls.  This plight of bees is a theme well-chosen as bee populations have been decreasing at an alarming rate in recent years, with bumble bees in the U.K. estimated to have fallen by 60% since 1970 and in some parts of the country, honey bees by up to 80%.  The repercussions of this disease are enormous with the bees pollination services, having a commercial and economic value of around 20 to 50 billion pounds worldwide, as bees don't just make honey, but they pollinate more than 90 of the flowering crops we rely on for our food sources.

Wellcome Trust Scientist, Pat Goodwin explained why these services are so valuable.

Pat -  Fruits won't ripen, we won't get flower seeds without having pollination which actually fertilizes the seeds so that they can grow into fruits.  Apples, pears and all the flowers that we love in our gardens, they depend on pollinators as well.

Group of feeding bumblebeesMeera -  So no more apples, pears or pretty flowers?  Pat told me more about why these decrease is thought to be happening.

Pat -  Nobody really knows the answer.  There are lots of theories.  One thing is climate change which is the warmer winters are affecting bee hibernation for example and upsetting their whole, sort of, life cycle.  There's new pathogens coming up, the Varroa mite, but it's not just the Varroa mite.  It carries viruses, so it lives on the bees, but it also transmits viruses between bees, then there's lots of issues around modern agriculture. Whereby you have vast fields which are then harvested, so there's nothing left for bees to pollinate and because they use the nectar and then take it to their hives and make it into honey.  Another thing I think, is probably in breeding, bees have been bred to be non-aggressive and to produce lots of honey, and that is probably meaning that they're loosing some genes which are important for their vitality.

Meera -  Now a buzz word at the moment, thought to be causing some of the big falls in population numbers is colony collapse disorder, where entire colonies are dying and disappearing for no known reason.  This has happened on a larger scale in the U.S. but is increasingly happening worldwide.  Bee keeper Steve Benbow has over 350 commercial hives nationwide.  So I ask how this plight in bee numbers has affected his trade and if his hives have experienced colony collapse.

Steve -  We don't really see that directly at the moment, but we do see trouble from say, Varroa, a parasitic mite that latches on to the bees and this brings in lots of other diseases such as cloudy wing virus.  It causes a deformity in the wings. The diseases we have to keep on top off and trying to sort of learn new techniques, things like icing sugar is a very good way of managing the Varroa which at the moment is being trialed where the bees do what we call a hygienic behavior, where they're cleaning themselves and hopefully, knocking off the mites and cleaning and grooming each other to help reduce this terrible infestation that can take place.

MVorroa miteeera -  So bee keepers like Steve Benbow are finding new ways to get around these problems.  But is getting around these diseases in honey bees, enough?  What about the other species being affected?  Well, April 2009 saw the launch of the Insect Pollinator's Initiative by 10 million pounds donated by many U.K. funders, including the Wellcome Trust and Natural Environment Research Council will be used to try and understand the decrease in bee populations.  Pat Goodwin told me how the initiative plans on doing this.

Pat -  What we hope to do is to bring together researchers in different fields to look at all these complex interactions and if we can understand what is underlying the issues facing bees, we might be able to do something about stopping it.

Meera -  So whilst researchers are trying to find out the causes and the cure to this problem, why not find out a bit more about it or even learn how to keep bees as a hobby, at this year's Pestival, taking place from the fourth to the sixth of September at the South Bank Center in London.

Multicoloured flowers

Colour your own flowers

Find out how to make your own garishly coloured flowers, and how it relates to the way plants lift water to their leaves.

A Rice Plant

30:19 - Transgenic Plants

Production and Advantages of Transgenic Plants

Transgenic Plants
with Professor Jonathan Jones, The Sainsbury Laboratory, Norwich

Chris -   Now, one of the things that farmers have to do is to combat the problem of plant pests.  And at the moment, they tend to do that in one way which is by using chemicals to treat the problem.  But one alternative could be the use of genetic techniques.  In other words, we could take genes from one plant or perhaps even a totally different species that knows how to destroy a pathogen, give it to a plant and that plant then has the ability to ward off that pathogen chemically, but without farm having to add additional chemicals.  How do we do this and why is it any better than existing techniques?  To tell us, here's Professor Jonathan Jones, he's based at the Sainsbury Laboratory in Norwich.  Hi, Jonathan.

Jonathan -  Hello there.

Chris -  And welcome to the Naked Scientists.  First of all, if you would, just tell us, how do you actually make a genetically modified plant?

Jonathan -  Well, a plant carries 50,000 genes or so, and the idea was to put in a gene or two that confers a useful new trait.  And to do that, you take advantage of a bacterium called agri-bacterium which naturally causes galls on a number of crops, particularly grapevine but a number of others too.  And it does this by introducing DNA into the cells of that plant, that make the plant more conducive to the growth of bacterium.  And what scientists have done over the last 30 years actually, is to understand this process, break it down into components, and then use their knowledge of the DNA  that transfers the DNA into the plant cell and get rid of the genes that make the plant cell do a number of growth characteristics that are not good for the plant.  And then you can put in genes that confer properties that would be advantageous for the crop and then what you do, is you incubate the plant cells with the bacteria and then you select for those plant cells that receive the genes that you're interested in and then at the end, you get a plant back from that, that has 50,000 genes it started with and has a couple of new genes as well.

Chris -  What sorts of things have scientists done, in terms of actually making functional crops that will be useful?  What sorts of genes have they inserted to enable crops to do novel things?

Jonathan -  The first thing that was done was to help farmers control weeds.  And so, in the absence of weed control, you can lose 30% or 40% of your yield.  I can go into my back garden and do some hoeing to control weeds, but they're constant problem, as anyone who has ever grown any crops or allotment will know.  And if you go out in a 50 hectare field or whatever to control weeds, then there's no alternative really to herbicides.  And the problem is that many herbicides are damaging to water courses, they're quite persistent.  And so, the herbicides that were being used a lot in the '70s. there's a strong incentive to replace them with something that was less persistent.  And the main one that was adopted worldwide was the glyphosate resistance trait.  So, glyphosate is a very good herbicide but it kills all known plants including the crop.  And so, what was done was to engineer in a gene that meant that the crop survived the glyphosate and so, the weeds were better controlled.  And glyphosate is inactivated quickly in the soil so, it's less damaging way to control weeds than methods that it replaced.  Subsequent to that, then there was an insect control.  So there were proteins that are toxic to larvae of moths and butterflies such as the boll weevil, such as the corn rootworm, such as corn stem and cob worm.  And so, you can engineer the plant to make a protein that kills the insect and that's better than the technology it replaced which was applying insecticides.

Chris -  Can I ask just you something about the practice of making a genetically modified plant because...

Jonathan -  Yes.

Chris -  ...when you actually put the foreign gene from one organism or one plant species into another to give it that resistance, do you know where into the plant's genetic material that had integration, that insertion has occurred or is it to all intents and purposes random?

In an effort to reduce corn stem-borer infestations, corporate and public researchers partner to develop local [transgenic] Bt (Bacillus thuringiensis) corn varieties suitable for Kenya.onathan -  Where it goes in any particular transformation event is currently unpredictable but you can then find out were it went.  Because what's actually done to bring some of the commercial variety is to make hundreds of transformation events or even thousands and select one that has no, shall we say, collateral damage in terms of the performance of the plant and then characterize where it went in very thoroughly.  So, anything that's on the market is very well defined, where the gene went in.  There are new technologies becoming available to put DNA in at a defined position and currently, that's experimental but it looks promising.  But no crops resulting from that technology are yet anywhere near commercialization.

Chris -  Because if I might ask you very briefly, just to give us the answer to this, which is that, if you got to say, a gene in a plant which is not essential for that plant to grow, but it does for instance remove a toxin that might be bad for us if we ate the plant, but it doesn't really harm the plant, if you put your new gene into the plant and it deactivated that gene that gets rid of that toxin or it makes the plant, so it's more vulnerable to something else, it might grow a mold which is bad for us if we eat it.  How do we know that hasn't happen and that therefore, we haven't had some kind of knock-on effect to the safety of the crop?

Jonathan -  Well, when I said that there's a lot of transformants was made in any such experiment which then screened for their properties or whether there's any collateral damage, that's the kind of collateral damage that people look for.  There'll be experimental acres, you know, large area devoted to this trialed crop before it hits the public and if anything like that would happen, it would become clear at an early stage before it reached the market.

Chris -  And we will be talking about organic farming in just a second.  Why is this better than organic techniques?

Jonathan -  I mean, the problem with organic farming is that yields are low.  Lower than conventional agriculture.  It is true that they cause less collateral damage, there's less risk of nitrogen run off into water courses, there is certainly no insecticides applied, although that you use copper sulfate to control late blight in potatoes.  But the main problem is yield.  By 2030, we're going to need to double yield because of the growing population and because of increasing demand throughout the world for more meat in the diet.  And to double yield it is going to be tough ask and I don't think it is going to happen with organic agriculture.

Chris -  So basically, we need the technology that you're coming out with.

Codling Moth Larvae

Biodynamic pest control on organic farms
with Professor Jane Memmott, University of Bristol

Helen -   Organic farming may not necessarily produce the yield we need to feed the world in future years, but it is booming business, it's increasingly popular and they go about - organic farms go about dealing with the same pest that conventional farmers face but in a different way.  We sent Ben Valsler let meet Professor Jane Memmott at Bristol University to find out more.

Codling Moth LarvaeBen -   How do organic farms deal with pests? Conventional farmers use pesticides to kill them off, but organic farming relies on the natural predators present acting as bio-control agents to kill off the pests.  This is known as Biodynamic pest control, and it's a major part of organic farming, which limits or excludes both pesticides and synthetic fertilizers, with the grand  aim of improve the health of soils and ecosystems.  Biodynamic pest control relies on having high biodiversity - a wide variety of plants, insects and animals in the ecosystem.

To see if biodynamic pest control really works, Professor Jane Memmot at the University of Bristol, found 40 farms to compare - 20 organic and 20 conventional.  To get a real understanding of what's going on, Professor Memmott's team were looking at the useful roles that organisms play, such as pollination or pest control, also known as 'Ecosystem services'...

Jane -   We wanted to look at the scale of the whole farm, and we also wanted to look at interactions between species, because ecosystem services, all of them, are about interaction between species.  Whether it's a caterpillar pest and its bio-control agent, whether it's between a flower and a bee that leads to an apple or a tomato or whatever, they all involve interactions.  So rather than just counting species, which is what previous studies have done; they count how many birds or how many beetles or how many spiders are on organic and conventional farms and compare the two, we wanted to put together food webs.

A quarter-inch-long parasitic wasp, Peristenus digoneutis, prepares to lay an egg in a tarnished plant bug nymph.Ben -   In an ambitious project, Jane and Bristol University undergraduates set about mapping and sampling all 40 farms -observing all of the plants, predators, prey and pest species present.  They payed particular attention to parasitoids - organisms which spend a portion of their life parasitizing another.  As gruesome as this sounds, parasitoids that target caterpillars are essential to pest control...

Jane -   So every month a team of people would go through the farm and sample transects in each of the different habitats.  To do that you walk through or go through on your hands and knees, through the habitat, and you're collecting all the caterpillars and all the leaf miners in that habitat, and you're counting all the plants that are in that habitat.  You then take your caterpillars back to the lab and you either get a moth or you get a parasitoid out of them.  So that information can then be used to join up all of the species into food webs; who eats who, which caterpillars eat which plants and which parasitoids eat which caterpillars.  And we've got one of those for each farm.

Ben -   The food webs predictably showed that there was slightly more biodiversity on the organic farms than on conventional farms, but food webs alone cannot tell you how effective an ecosystem is at tackling pests...

Jane -   So what our prediction was next was that the organic farms would provide better biological pest control.  You've got more species of parasitoid on there, more semi-natural habitat, so they should give you better pest control.  Indeed, the whole ethos of organic farming is that one of the reasons they don't get as many pests is because they've got all these beneficial insects that eat all the pests.

Organic cultivation of mixed vegetables on an organic farm in Capay, California.So what we did next - it's actually my favourite bit, it's the clever bit - was that having got the networks we then decided to manipulate them in some way.  Now what we wanted to do, the ideal experiment, is to find a pest, a new pest, and put it on all farms and see if they're better controlled on the organic farms.  But you can straight away see that that's not going to work.  It's ethically, morally suspect, you just can't do it - the farmers would never let you back again!  So you can't do that so what we did instead was we found a surrogate pest, we found something that was pest like but would not appear on the farms naturally, and we could use as a kind of surrogate pest to ask what would happen if a new species of insect came in.  And the particular insect we used was a thing called the Pyracantha leaf miner.

Ben -   As its name suggests, the pyracantha leaf miner is a pest that lives inside the leaves of the pyracantha plant - a hardy, prickly plant that wouldn't normally be found on a farm.  By planting 40 pyracantha bushed on each farm and introducing the leaf miners, they can act as a surrogate pest to show the level of natural pest control.

Jane -   And what we found really surprised us, because we found that for this particular species, the pest control was no better on the organic farms than on the conventional farms.  So there was no difference whatsoever in the number of them killed.  So this kind of made us scratch our heads a bit.  And what we did then was, because we have these networks for each farm, we went back to our networks and asked, well, how many parasitoids are there that would probably attack this species?  And actually it turns out that when you retrospectively predict what could attack it, there really aren't more species of parasitoid on organic farms than conventional farms.

Red pommes of Firethorn (Pyracantha). Shot near Tō-ji temple in Kyoto, Japan.Ben -   Using the same data, they were able to predict that just three of more than thirty families of insects would be better controlled on the organic farms - Professor Memmott now plans to introduce surrogate pests from each of these families, and see if biodynamic pest control really does work.

So what does this mean for organic farming?

Jane -   The conventional farms all have lots of semi-natural habitat on them, so they are kind of getting this pest control for free and they don't necessarily realise that it's there.  So it's not just having more biodiversity, it's actually having the right sort of biodiversity that's really important.  Conventional farms can actually get an awful lot of the biodiversity gains of organic farms without going wholesale organic.  We're never going to have more than about 5-10% or farms organic in the UK, I don't think, ever, so that 90% of other farms, if they can make small changes in what they do that could actually have a really big effect on biodiversity nationwide.  And if they can take some of the things that really work from the organic farms which don't involve wholesale conversion to organic-ness, then that could reap huge biodiversity gains across the country.

Ben -   So adopting certain aspects of organic farms - for example growing healthy hedgerows and areas of semi-natural habitat, or reducing reliance on pesticides - could see conventional farms bursting with biodiversity, and naturally protected from pests.

Jane -   But little changes from the great majority of conventional farmers, rather than having another 2% of organic farms say, could make the most enormous difference.

Chris -  So you don't need to be totally organic.  Just a bit organic would do.  That was Professor Jane Memmott, she's at the University of Bristol and she was talking to our own Ben Valsler.

44:26 - Seawater Greenhouses

Using greenhouses to create freshwater from seawater in arid countries.

Seawater Greenhouses
with Charlie Paton, Seawater Greenhouse Ltd

Helen -   It doesn't matter how you grow your crops, whether they're organic and it doesn't matter on how you're going about, trying to deal with pests.  There's one thing that crops will always need and that is water.  Well we're now joined by Charlie Paton and he's the Managing Director of a company called Seawater Greenhouse and the name might be a bit of a give away but we're going to find out from him, all about what he's been up to. Hi, Charlie! Thanks for joining us.

Charlie -  Yes, hello.

Helen -  First of all, could you describe what this Seawater Greenhouses are and what's the problem you're hoping to solve with and why do we need them?

Charlie - Okay.  The greenhouse is - most people think of greenhouses as hot houses - well these are "cool houses" because we cool them with sea water.  So they're designed for hot Arab climates like North Africa and the Middle East and Australia, and we cool them by using sea water which we pour over a kind of construction which is a honeycomb cardboard material which is a cross between a honeycomb and if you like, a sponge.  So we have a very large surface area of wall that is wetted with sea water.  Now, when the air comes through that, it's cooled and the humidity goes up.  So, by cooling the air and raising the humidity, we create conditions that plants will grow in, when they wouldn't have otherwise.

Helen -  So, you want to grow plants in the middle of the desert where really, they just wouldn't grow normally because it's hot, too dry, there's not enough water.

Charlie -  Exactly.

Helen -  So you're cooling things down and you're creating water as well.

Charlie -   And we're creating water as well because at the back end of the greenhouse, we have another arrangement with a similar evaporator but this time, we put hot water, hot sea water over the back evaporator before the air goes out of the greenhouse.  And then it passes through a small heat exchanger which is cooled by the water that we cooled on the front wall.  So, it's rather like having a hot shower and seeing water condense on bathroom mirror.

Helen -  Right.  Now, do these things have to be built near the sea?  And then also, what do you do with the salt once you get rid of it, when you've produced this fresh water?  Presumably, you have a very strong brine left over at the end.  What do you do with that?

Charlie -  At the moment, we put the salt back into the sea water, but our intention is, in the future to separate out the various minerals and indeed, use it a lot of them for the plants themselves.

Helen -  So, you can use that as well to help grow the plants but the plants do need those salts but in different quantities and different amounts?

Charlie -  Well, exactly.  If you can, in simple terms, if you can take the salt that is a sodium chloride out of sea water, you've got a very good, babybio type mixture which has got all the trace elements and a lot of the nutrients that the plants need.  And in fact, seaweeds and fish meal are perhaps the best fertilizers you can get.

Helen -  Now, does this need any electricity because I believe, one of the big problems with using desalination plants, is they're really energy hungry.  You have to use a lot of energy to create that fresh water.  Are you using any electricity at all in you're greenhouses?

Charlie -  Yes, we are.  It's a very small amount of electricity and it's extremely efficient.  We use, typically, if I can put this in perspective, we need power for the pumps and the fans which regulate the airflow and typically, we use around two kilowatts of electricity to remove about a megawatt of heat.

Helen -  So that's good, is it?

Charlie -  It's very efficient.

Helen -  Excellent.  And in terms of the efficiency of what you're growing and say, how big a greenhouse would you need to feed a family or maybe a village, if you like?

Charlie -   Oh, there is no limit.  I mean, greenhouses are made in a modular sort of way and there's no limit to the scale.  I mean, at the moment in Europe, we get a lot fresh of our fresh produce from greenhouses and those in the South of Spain for example, there was  40,000 hectares of greenhouses, primarily producing out-of-season crops for us in Europe in the winter months.

Helen -  So, would this work in countries like Britain or are you really aiming at those very dry, arid countries?

Charlie -  No.  It's aimed at places like North Africa, the Middle East, Australia, India, and those sort of places.

Helen -  I believe you've got a project, is that right?  Called the Sahara Forest project.  What's that about?

Charlie -  That's right.  We've sort of taken it one step further and I'm not sure if you're familiar with concentrated solar power.  But it's a process that's getting more and more interesting and people getting more excited about. Where you very simply have an array of mirrors in a hot sunny place and the mirrors are focused onto something that heats up water and you turn that water to steam and you use that steam to drive a steam turbine.  And there are various different versions of them, but several have been built and there were quite a lot being planned.  And there's some fairly grand schemes for Europe to actually source its electricity from the Sahara through these systems.  Now, our thinking is that as with any thermal process that makes electricity, there's a lot of heat to be got rid of.  And that if we have that sea water greenhouses in the vicinity of these power plants, we can take that waste low grade heat and use it to evaporate and condense a lot more water.

Helen -   Thanks Charlie, that was Charlie Paton, he's the Managing Director of Seawater Greenhouse - they're developing an elegant system to both grow crops and supply freshwater to arid areas!

Why is the demand for meat increasing?

We put this question to Professor Jonathan Jones:Well, many would say, quite reasonably, that we shouldn't increase the meat demand, but the fact is that we will. It's clear that China's appetite for meat in their diet in particular is going up and up. These are people who, from having rice seven days a week, now want have rice plus meat in one day out of seven and maybe even two days out of seven. And so, as affluence goes up, demand for meat will go up, and I think it's unfortunate because we could reduce our impact on the environment if we ate less meat, especially in the West. But anyway, I think that's what's going to happen and a major trade pipeline is soy beans from Brazil to China to grow pigs.And to Charlie Paton:It must be in everybody's interest to eat less meat and therefore, it must be in everybody's interest to have greater biodiversity of fresh produce and that is one of the things we're very interested in, in encouraging.

Could we collect steam from power plants as fresh water?

We put this question to Charlie Paton:Well that's essentially what we're talking about [with Sea Water Greenhouse]. Yes. Exactly, that's the same thing.

Are fast-growing GM plants weaker?

We put this question to Professor Jonathan Jones:Well usually, they don't grow a lot faster. They're just more disease resistant. So you'll have less losses. So if your roots aren't eaten by corn rootworm for example, they're actually stronger because they can take in more water. The roots are not removed from the equation, so the water harvesting from the soil. Both for the plant, is more efficient.

Could I inject DNA from one plant into another to make a new fruit?

We put this question to Professor Jonathan Jones:What distinguishes one fruit from another, involves more than one gene. It's pretty complicated. If you want to convert white grapes to red grapes, then the gene that distinguishes them is defined. You could put that gene and get a red grape back, but you couldn't change species with one gene.

When will seawater greenhouses be available?

We put this question to Charlie Paton:Well, we've built three and we've got three demonstrators working in different parts of the world and we are planning a fairly large scale commercial operation in Australia which will happen some time, I hope, later next year and we're working quite intensively on the Sahara forest idea. We don't know where we're going to start but we're putting the numbers together.

Will seawater greenhouses be affordable?

We put this question to Charlie Paton:Well, it's a method of creating wealth in a sense because if you have no water, you can't do anything. If you have water, you can create jobs, you can create food, and you can create energy.

Why does it smell so nice after it rains?

The answer to this was quite slow coming and no one really knew for sure, perhaps we still don't know for certain, but there was certainly some work done on this in the 1960s and the paper got published in 1966 where scientists actually, they think got the answer. The theories where that this could either be something coming out of the soil, something reacting with water in the soil to produce the smell, or perhaps something organic, something living and it turns out, it's probably the latter. A group of scientists analyzed the air and they found that when you took soil, you find a very common soil bacterium called actinomycetes. This is a filamentous bacteria and it grows lots of little filaments that ramify through the soil, picking up nutrients. But it also has another form which it uses to protect itself when the soil is very, very dry. So, when there's severe arid, dry conditions, it recedes into a spore and this is a dormant form of the bacterium from which it can reactivate when water comes back and the soil is fresh and there's lots of good environment for it to exploit again. So what scientists think happens when you get a rain shower and it produces that beautiful earthly smell in the air, is that the rain comes down, it hits dry soil where all these bacteria have formed this little spores, the spores then get ejected up into the air, and they drift around in a cloud. Because they're so tiny, they stay drifting around in the cloud for quite sometime. You then breathe them in and they smell the way they smell. That's their smell. But it's also a form of, sort of, dispersal for the bacterium because it then descends on another patch of ground, out of the air and can germinate and grow. So, I suppose that's one point. Another thing to bare in mind is of course, there's the other possibility that was also raised by scientists historically and that is that there are various chemical reactions that can occur when water hits soil or dry soil or a rock. And so, it might be that some of these smells, because of particular rocks getting wetted, then chemical reactions are being elaborated and then they produce various chemicals that go up in to the air. But we think it's mainly the actinomycetes, that's the main cause.

Laundry soaps in Jaffa flea market

Why do washing powders remove stains but not dyes?

So an answer to the first part; one of the main and important ingredients used is surfactants and the surfactant molecule is clever in the way that on one side it has a hydrophobic component, that's a water-hating molecular chain. And on the other side, a hydrophilic water-loving component. The hydrophobic chain finds itself sticking to the stains on your clothes and the hydrophilic heads have a stronger attraction to water. They're able to surround the dirts and roll it up into a small globular-type ball and the end result is that they're able to lift the stain from your cloth, into the wash water. Some of our detergents contain enzymes which are naturally derived molecules. Generally, we use different enzymes such proteases which break down proteins and amylase which breaks down starch and then finally, another major ingredient that we use, like most other detergent manufacturers is bleach. The bleach turns the stain into more soluble colourless particles that can be easily removed and carried away into the wash water. So, in actual fact, it can remove bleachable dye stains. So, to kind of answer the other part of the question, laundry detergents can remove certain dyes, as well as stains.Most dyes are composed of molecules that these ingredients can't target. Surfactants can't globuralize the dyes, nor can enzymes gobble them up, unless they're vegetable-based. But bleach can effect dyes and this is why, washing powders designed for colored clothes don't contain any bleach.

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