Egg-cellent Easter Science

Easter Eggs are traditionally distributed by the benevolent Easter bunny. But there's one problem, where would a rabbit find an egg? They certainly don't lay them, but why not? Graihagh Jackson took a trip to London Zoo to search for an answer...

Graihagh - I have four beautiful rabbits - Walnut and Hazel, Smudge and Pushkin. I've been wondering for a long time whether they might surprise me one year and lay a chocolate egg for Easter because that's what the Easter bunny does, right? Well, maybe not and at least it's not only my pet rabbits that aren't grateful enough to lay me an egg. Of course, there's a huge evolutionary diversity in the animal kingdom when it comes to reproduction. In team one, you have the live-birthers and in team two, the egg layers. One of the top players in team 2 are the birds. But why do some animals lay eggs and others give birth? What's better, and who does what? To get the egg rolling, I played a game with ZSL zoologist Jon Bielby in the birdhouse of London Zoo. The game is, birther or egg layer. Winner gets a gold star. Ready, set, go...flamingo.

Jon - Egg.

Graihagh - Giraffe.

Jon - That will be a live young.

Graihagh - Panda.

Jon - Live young.

Graihagh - Penguin?

Jon - Eggs.

Graihagh - Duckbill platypus.

Jon - That's a tricky one. It's a mammal, but it lays eggs.

Graihagh - So, there's sort of a 50/50 split there between live young and eggs. Is that the same across the entire animal kingdom or is it less evenly distributed than that?

Jon - Across the whole animal kingdom, it would be less evenly distributed than that. You'd have many, many more animals that lay eggs rather than giving birth to live young.

Graihagh - These two main varieties, what's the benefit? Why does some animals lay eggs and others give birth to live young?

Jon - The main reason is that there are lots and lots of different ways to make a living. So, we're walking around London Zoo, you see tons of different ways that animals do things - sizes, diets and that includes how they breed, how they reproduce and what their young do. We think of all of vertebrates, all the things with backbones so fish, amphibians, reptiles, birds, mammals. The default setting is laying eggs and that's because the ancestor of all of those different types of animals laid eggs. But at various points across that family tree giving to live young has evolved in different ways. So, both are equally successful. Both allow animals to pass on their genes and that's what natural selection and evolution is all about really.

Graihagh - If we all started as egg layers - I'm laughing at the image of myself laying an egg - why would we suddenly evolve and across so many different animal kingdoms as well, how did that happen if you like?

Jon - The reason why it might happen is that a population or individuals within a population would have a mutation to their genetics. What it meant is that instead of laying eggs, they'd maintain their eggs for a little bit longer in their oviduct and then they'd lay eggs that would hatch ouy more quickly and so on and so forth. And if they survive better then their genes would be passed on to the next generation.

Graihagh - Is there any examples of it going the other way around say, from live birth back to laying eggs?

Jon - As far as I'm aware, it's not gone the other way as yet.

Graihagh - But what about the Easter bunny because he or she famously carries around chocolate eggs? Jon and I sauntered down to the rabbit enclosure to find out if this myth could possibly be true. Could my pet rabbits lay me an egg this Easter?

Jon - I don't think you're going to go home and find that your rabbits have laid eggs. Have rabbits ever laid eggs? Sorry, no, I don't think so.

Graihagh - Would they ever evolve to lay eggs in the future?

Jon - I think it's really, really unlikely. There are a couple of reasons for that. One is that if you think of how different laying an egg is, compared to giving birth to live young. So, if you look at your egg that you might have for breakfast, you crack it up and you've got the yellow bit which is the yolk and then there's the white bit which is a protein. The shell itself is really specialised piece of equipment if you like for looking after a chick. In a rabbit, what would happen is that the young rabbits inside the mother would feed through the placenta. Think of a placenta compared to an egg. It's really, really different. Now, the first reason I think is, it's really unlikely that you're going to go home and find that your rabbits have laid eggs is that having evolved all of this really elaborate way of looking after the young via a placenta, it's really unlikely that the body is physiologically going to be able to change and go back to lay an egg. I don't know whether that's impossible or not but if you think about if that happened over thousands or even millions of years, it wouldn't really be a rabbit anymore. It would be something else. But the other reason is that rabbits are really successful, so that really need to do that. Rabbits breed like rabbits. There are millions of them. So, there's not really the pressure for them to go back to laying eggs.

Graihagh - You've just smashed on my hopes and dreams of the Easter bunny ever coming to visit.

Jon - I'm really sorry about that. I mean, you might still get some Easter eggs this week and I'm not sure. But yeah, probably not laid by a rabbit.

Graihagh - So, did the Easter bunny steal his eggs from the chickens then? Is that what happened?

Jon - It's possible, but as far as I know, the eggs that the Easter bunny delivers are chocolate. As far as I know, chickens don't lay chocolate eggs. I'm not sure how that happened biological speaking.

Graihagh - There aren't animals that lay chocolate eggs I'm assuming.

Jon - It would clearly melt inside of the oviduct, so it's just not going to happen. I suppose maybe that's why they got protective tinfoil insulation or something.

Where would Easter be without chickens? There are something like 30 billion of them on Earth, and with these sorts of numbers, bird flu is a big concern. Not only can it wipe out a farmer's livelihood, it can also spread to humans and cause a pandemic. Biologist Laurence Tiley thinks he has the ideal Easter treat - a genetically modified hen that can't contract the flu bug. At the moment they're an alarming green colour, but he's working on that...

Laurence - Flu is a virus, which means it's a very tiny organism that's completely dependent on infecting a cell and replicating within the cell of a host. It's not like a bacteria, which it can sort of free-live. It has to actually get into an animal in order to reproduce itself. Flu causes disease in a lot of different species - horses, pigs, chickens are the ones that most people know about.

Chris - How much of a headache is flu for farmers of chickens?

Laurence - It can be a big headache. Strains that are, what we call highly pathogenic influenza viruses, they will kill 99% of a farmer's birds in a space of a couple of days. So, we're trying to make strains of chickens that are intrinsically resistant to influenza or infection.

Chris - They can't catch flu.

Laurence - That's the ultimate goal, yes. We've made progress towards that. We've got birds that although they can still be infected, they don't pass the infection on to other birds.

Chris - How?

Laurence - By putting a new gene into the bird that produces something that throws a spanner in the mechanics of the virus. It cums up the ability of the virus to copy itself and transmit on from one cell to another. The virus has to copy itself in order to reproduce and be able to cause an infection and spread from one cell or one animal to another. The way it does that, it uses an influenza virus protein and enzyme that can copy and make new versions of its genetic material that it can then package up into new particles and those new viruses. So, we've introduced something into the genome of the chicken that produces a small molecule that looks like a flu genome. When the virus infects those cells, it gets diverted into copying this little decoy rather than copying its own genome.

Chris - So, the virus infects the cell. Because you've got your little thing that looks a bit like a virus component sitting in the genetic material of the cell, this also starts being copied. It side-tracks the cell into focusing on that rather than on making viable flu viruses in that cell.

Laurence - That's the theory behind, yes.

Chris - Have you actually done this yet? Have you got chickens that are making this molecule?

Laurence - Yes, we've made chickens that have got a new gene inserted into them and that produces this particular molecule. We've tested them and shown that it does interfere effectively with the transmission of the virus from one bird to another.

Chris - Will this work for all of the different strains of flu because one of the things about flu is it comes in many different flavours? You hear about H1N1 and H3N2 in humans. Birds have maybe 17 of these different combinations, don't they? So, will your thing work against any type of flu that comes along?

Laurence - I think that's the beauty of this particular approach that we're taking is that the little bit of genetic material that we're introducing looks like this piece of flu, is absolutely the same in all of those strains of flu. It's a very, very important control element for the virus so there's very limited opportunity for it to evolve around it.

Chris - What about safety? Because people are very worried particularly in the wake of things like BSC, which is another example of things getting into the food chain that people would rather not had in the food chain. Is there any risk to the people who might eat these chickens?

Laurence - No. the nature of the molecule that we've introduced into the chickens, it's not a protein for example. So, there would be no chance of anybody developing an allergy to it. The type of molecule it is would not be recognised by our immune system. It would have absolutely no effect on somebody who ate it and the chickens are producing this in every single cell of their body and they're absolutely normal, except that they're bright green because we use a fluorescent marker to track which ones are genetically modified and which ones aren't. Clearly, when it comes to the human food chain, we wouldn't be trying to flog fluorescent green chickens.

Chris - I don't know, a glowing green chicken might make quite a good marketing gimmick. That was Laurence Tiley from the University of Cambridge.

A key symbol of the Easter holidays is resurrection. Christians may celebrate a famous resurrection on Easter Sunday, but according to the Bible, Jesus definitely wasn't brought back to life by dunking him in water. However, that's exactly how a new breed of preserved vaccines and drugs are resurrected, after being held in suspended animation in a special sugary glass - a discovery that could revolutionise vaccine delivery across the world. Kat Arney spoke to Cambridge-based scientist Bruce Roser to discover how the technology works.

Bruce - All vaccines and many drugs are stored in the refrigerator. Absolutely, it have to be stored in the refrigerator because outside of the refrigerator, they're unstable. This is particularly true of vaccines and particularly a problem of vaccines because they have to be shipped all over the world to remote places without access to refrigeration. It’s an enormous job for the WHO to put a mine of refrigerators all the way from the factories in the west to remote towns in Africa. So, that’s the problem. How do you stabilise vaccines and other drugs so this is not required?

Kat - Where did you look to for your inspiration?

Bruce - The inspiration came out of the blue. I was asked to make a presentation at the Royal Society and one of my problems was that the reagents I was using are very unstable and a colleague suggested to me that I read a paper about how to address unstable proteins with simple, natural process. So, I read this up and I discovered these living organisms called anhydrobiotic organisms that were able to dry out during a drought and then come back to life again when water was added back to them even after a hundred years. These are things like the resurrection plant. There are also some animals that do this and of course for example, baker’s yeast. You can buy those dried powder in the supermarket, add water to it and it comes back to life.

Kat - Very appropriate if anyone’s been making hot cross buns this weekend I suppose.

Bruce - Exactly, yes.

Kat - Tell me a little bit more about what's going on in these organisms to enable them to preserve themselves for so long.

Bruce - When I started to study this issue, two things were noted by previous people where one had – these organisms could dry out and come back to life and the second is that they contained a lot of the very unusual sugar called trehalose. Being completely in this entire thought, well obviously, trehalose causes this phenomenon whereas almost anybody else who knew anything about it said this is much too complicated process for it just to be due to a simple sugar. But I did some experiments and found that the simple sugar would exactly replicate what was happening in these organisms. It turns out that the process is very beautiful and very simple. When you dry these organisms, all the sugar that they have inside their tissues doesn’t crystallise as the animals dry out the way normal sugar crystallises. But it becomes more and more viscous like honey which would’ve turned into a thick syrup. As you remove more and more water, it gradually solidifies into what's called a glass. These glasses are made of sugar so that they dissolve very easily in water. the molecules that were floating about in these organisms while they were alive become trapped in this viscous sugar solution and eventually in the glass so that they can't move about, they can't interact with each other and therefore, they can't deteriorate. So, they're trapped in suspended animation if you like in the sugar glass.

Kat - It’s a wonderful image of all these little molecules just trapped forever, almost like Han Solo frozen in time in his carbonite.

Bruce - Exactly. A better principle is probably some of the living insects that you see trapped in amber. These all happens at room temperature or above. You don’t have to use any freezing at all. Of course, that’s why it’s so valuable for vaccines in the developing world.

Kat - If all you need to do this process is some molecules, some living things and some sugar, does it work for everything? Could you make it work for any vaccine you wanted?

Bruce - Yes. We’ve done about – I think it’s about 20 vaccines and it works with all of them. We don’t have much doubt that it will work with anything that’s given to us.

Kat - We’ve heard so much in media over the past year about the Ebola outbreak in western Africa. Do you think that potentially, Ebola vaccines could be preserved in this kind of way too?

Bruce - What I know about Ebola vaccines, they are the sort of vaccines that we’ve worked with before, with which the technique works perfectly.

Kat - It does sound absolutely fantastic. So of course, the big question is, how soon? When can you start getting this kind of preservation technique out into the world?

Bruce - We’ve got to the stage now where we’re in animal trials. So, we’re hopeful that if our animal experiments go well, we should be able to get approved in humans very quickly. So, we’re talking about 2 to 5 years, hopefully, closer to 2.

Easter just wouldn't be Easter without consuming obscene amounts of chocolate. But for most of us, it's something we enjoy with a bit of a guilty conscience, worrying what it will do to our health and our waistlines. Wouldn't it be nice if this wasn't the case? Ginny Smith went to visit Lycotec's chocolate lab in Cambridge, where the founder of the company, Ivan Petyaev, explained how they are developing a range of chocolates that are actually beneficial to our health... 

Ivan - Majority of people, one way or another, eat chocolate. It’s a treat most people love basically and we want not to change people to do something they don’t know, eat something different or a few people eat it. Whatever the reason, people do go for chocolates.

Ginny - Now, I've heard a lot about kind of health claims around chocolate particularly dark chocolate that it’s really good for you and all these different ways. What is it in chocolate that gives us those benefits?

Ivan - We identify a number of active molecules which is really responsible for a certain kind of benefit. It ranges from neurotransmitters which are present in the chocolate, two, caffeine, and in the last 20 years, main attention really focusing on new molecules they found which have been there all the time called polyphenols and flavanols. They're cousins or the same molecules which is in red wine, the same which is in the blueberry.

Ginny - What is it about polyphenols that are good for us? What do they actually do in the body?

Ivan - Polyphenols, it’s a type of molecules which is sitting on a surface of the cell membranes because it’s a little bit lipophilic. Also, it’s a bit water soluble.

Ginny - So, the molecule is both attracted to the fats around the outside of the cell, but it’s also soluble in blood.

Ivan - Yeah, absolutely right description because it’s sitting on a surface of a membrane exposed to the blood, to the plasma. This is a unique position because this is where all drama in the cells happening where the disease come. Oxidation starts from outside. Inflammation starts from outside. It means, you need to help cells to control this process.

Ginny - So, is it effectively protecting the cell from attackers in the blood?

Ivan - Exactly because when the cells get attacked by damaging factors, it would protect them and this has been described in many studies and we really like these properties.

Ginny - So, if chocolate is full of all this good stuff anyway, what makes your chocolate better?

Ivan - We’re not really bringing new chocolate. We’re not bringing new molecules. We have a technology which allow us to deliver these molecules in very compact form and make them working. Our technology designed to protect these flavanols in the chocolate because actually, it’s only 1% of flavanols get absorbed to the blood. if we learn how to protect flavanol from the damage during digestion process, we can increase delivery of the flavanols and we don’t need so much chocolate to consume.

Ginny - Does that mean you're saying that there is a huge amount of flavanols already in the chocolate but we just can't access them because by the time they’ve got to our stomach, most of it has degenerated and it’s not useful anymore?

Ivan - This is exactly what is happening. 99% get oxidised by acidity and bacteria. It means we have very little left to absorb.

Ginny - What exactly is it about the technology you’ve developed that prevents that oxidation process and keeps those flavanols available for our bodies to use?

Ivan - We know that flavanols are sitting within the chocolate crystals and we’ve developed a technology that we can code these crystals or some of these crystals with other active carotenoids. So pigments like lycopene from tomato, lutein from spinach or astaxanthin as well from algae. Basically, they're very similar to each other but main property of them, they're not just able to code the chocolate crystals but they have acid resistance. It mean this is what give us – use them as a protector of flavanols during digestion process. As a result of this coating, we can have a high level of delivery of these flavanols to the blood.

Ginny - And of course, those carotenoid molecules you mentioned are very beneficial as well. We’ve all been told to eat more greens and eat more tomatoes because they’ve got these pigments in them that are so good for us.

Ivan - This is correct. If you combine the benefit of digestion of these carotenoids together with higher increased level of flavanols, we’ll have a very nice energetic, health beneficial effect.

Ginny - And we really can eat chocolate without feeling guilty about it.

Ivan - Yes, you can eat it and enjoy it. You can try yourself the taste and we’ll see how it tastes.

Ginny - That will be fantastic! So, have you got some here that I could try?

Ivan - Yes, please do.

Ginny - Okay, so which version of your chocolate is this?

Ivan - It’s contained astaxanthin. It’s from algae, make basically food chain all pink: prawns eat them. Fish eat prawns and the creoles, and all of them, all of these marine species will have astaxanthin.

Ginny - So, it looks just like a normal square of dark chocolate. It’s lovely and shiny and it’s got a very pungent dark chocolatey smell. I'm going to try a piece now. You promise me this won't taste of algae.

Ivan - No.

Ginny - I'm not detecting any algae at the moment. It’s a lovely smooth dark chocolate. It’s delicious. You wouldn’t know that this was a health food certainly.

Ivan - Well, this is the point. We don’t want to change taste.

Daring to stand on a carton of raw eggs; Chris Smith and Georgia Mills find out about the impressive structural properties of an egg.

Georgia - We're going to test the strength of eggs today and see if they together can support your weight. So, I've got a standard 6 eggs carton on the floor with 6 eggs in it. I haven't done anything to them. I've checked that there aren't any cracks in them and that's all. You're going to stand on them now.

Chris - This is this sort of cardboard carton that you'd get from the supermarket and there are 6 rather nice looking eggs in there and you want me to just stand with one foot to stand on that.

Georgia - Yes. It will be a shame if this goes wrong, but I have faith in the structural integrity of these eggs.

Chris - I have taken my shoe off. I'm putting my socked foot on top of the eggs in the egg box.

Georgia - And now, I want you to make sure your weight is evenly distributed across all of the 6 eggs.

Chris - Okay, I'm going to put my arm on you, just so I can just stay stable.

Georgia - Okay.

[CREAKING]

Chris - Okay, you wouldn't believe it and I'm very nervous doing this, but I'm standing on one leg, on one foot, on a box full of eggs. I'm genuinely doing that and they haven't broken.

Georgia - I'm just as surprised as you I think.

Chris - I'm very relieved. Honestly, I thought that my feet were going to go straight to them and I was going to have a very eggy sock.

Georgia - That's the amazing property of an egg. If we did this on their side, this wouldn't work at all. Do you want to try that Chris?

Chris - I'm not doing that, but let's just grab an egg. So, these really are genuine eggs. They're not hardboiled or anything. I can shake it. I can feel the sort of yolk and stuff slushing around inside. So, what's special about this that I can stand on it in that way?

Georgia - Eggs have a really good shape for this kind of compression. If you look at them, they're ovals. They're like an arch shape and we use this kind of shape in architecture all the time. you think about bridges, you think about domed ceilings. If you push on the top of an egg because it's such a narrow arch, the force is distributed all throughout the body of the egg. Meaning, it won't break. However, if you put a smaller force on the long edge of the egg, this actually squeezes in the inside of the egg as well and the eggs are really bad withstanding this kind of pressure.

Chris - What you're saying is, this egg is - because of its shape, when I apply force to the curved top of the egg, basically, I'm compressing all of the material in the egg in all directions. It's sort of transferring the force down all of the sides evenly whereas if I turn the egg on its side and I were to stand on that and I'm not going to do it - much to your disappointment, I won't be doing that. But if I were to stand on the side of the egg, then I would be bending the shell a bit and there wouldn't that transfer of load all over the egg. It would just basically bend the shell and it's not very strong when you make it stretch. It's going to bust open.

Georgia - Exactly, which is why when you crack an egg, you do it on the side. You'd never do it on the top.

Chris - Did eggs evolve to have this shape for that reason? Is that why the egg has got this property to stop the chicken literally cracking its own eggs?

Georgia - That's right. So, when a mother hen sits on her eggs, the last thing she wants to do is to squish all her babies. So, with these eggs pointing upright, it distributes her weight all around. But then when these tiny weak chickens need to get out, a small force on the side of the egg enables them to crack out of the egg.