Fruity vapes paralyse lungs, and world's oldest cheese
In this edition of The Naked Scientists: Signs that fruity vapes paralyse the immune system in your lungs; the world’s oldest cheese: but why was the nearly 4000 year old dairy product smeared all over an ancient Chinese mummy? And, why it might be a giant leap to suggest that we’re getting an extra moon, at least for a while!
In this episode
01:01 - Fruity vapes paralyse lung's immune system
Fruity vapes paralyse lung's immune system
Ajitha Thanabalasuriar, McGill University
A new study has found that berry-flavoured vapes can paralyse the action of immune cells that normal patrol the lungs and prevent infection. The study - which has just been published in the journal PNAS - and was conducted on experimental lab mice - is the work of Erika Penz at the University of Saskatchewan and Ajitha Thanabalasuriar at McGill University. Ajitha began by explaining how they ended up looking into this…
Ajitha - It really hit us in 2019 where there was this outbreak of e-cigarette related lung injury in teenagers. And one is the type of e-cigarette products that kids were drawn to. And that was marketed for them really, the fruity flavours and the candy flavours. And we thought, what specifically do these flavours do to our immune system?
Chris - What happened to those kids? What did they present with?
Ajitha - They presented with lung injury. So essentially they would go into the hospital and they looked like they had a flu infection, but when they did a test they came out negative for the influenza virus. And a large portion of these individuals who got sick, who got very sick or actually passed away, were in the US. And at the time there were a lot of studies done in the US and they kind of chalked it down to this one part of e-cigarettes called vitamin E acetate that was in their e-cigarette product. And since then they've banned vitamin E acetate from e-cigarettes and they've had fewer of these lung injuries and young kids. But the thing that was interesting is that vitamin E acetate was never allowed in e-cigarette products in Canada. And we also had those lung injury cases. And again, there were smaller proportions, but it still made us think there was something else to this story that we weren't catching yet.
Chris - So how did you pursue it?
Ajitha - My lab really focuses on something called intra vital microscopy we're actually able to image immune cells moving through the lungs of a live animal. And then Erika came in and she sort of suggested that we look at specific flavours that were really popular with kids. And so we focused on this like berry mixed flavour and we compared that to an unflavoured e-cigarette vape. And we looked to see how these mice responded to exposure to the e-cigarette products. And our outcome was this imaging technique where we were able to actually track these cells called macrophages, which are white blood cells in your airways, and we're able to see how they move around in the presence and absence of this flavoured e-cigarette product.
Chris - All I can see in my mind's eye at the moment is a mouse vaping. How do you do that?
Ajitha - So it's not exactly the same as humans. So humans can actually physically take in a puff from an e-cigarette device. Whereas with mice it's more of a passive treatment. So basically we put our animals into these little cages and then we expose them to an e-cigarette that's puffed through a machine and it just sort of blows it onto the animals and they inhale it passively. So it's more like secondhand smoke. And so what we did with the animals was that we exposed them to the e-cigarettes for one hour a day every day for three to 10 days. And we just really looked to see if there were subtle changes in our immune system.
Chris - So when you say you can see the cells, do you mean you can actually see the cells moving through blood vessels and tissues and then track what goes where?
Ajitha - Exactly. So our lungs have these spaces called alveolar spaces and they're essentially like these grape-like structures that are strung together and that's where our gas exchange occurs. And in those alveolar spaces we have these really important immune cells called alveolar macrophages. And what's interesting is that there are more alveolar spaces than alveolar macrophages and these macrophages are tasked with patrolling around each alveolar space and checking if there's anything that you inhale that's bad for you. The air we breathe is not sterile, it's filled with particulates, it's filled with bacteria and usually they are cleared by either inner nose, the mucus in our upper respiratory tract. But sometimes things do get down into our alveoli and these macrophages gobble them up. And their ability to do that relies on their ability to move and their ability to move around that alveolar space and between. And so we can actually visualise in a healthy mouse these alveolar macrophages moving around in alveolar space, and in between alveolar spaces.
Chris - Are you looking from outside the mouse then?
Ajitha - So it's a surgery that we put with a little window into the pleural surface of the lung. So we're not putting anything into the airways, we're actually looking from the outside in.
Chris - And what happens then when you compare animals that get this vape exposure with presumably equivalent mice that don't, how do they differ? What changes?
Ajitha - Alveolar macrophages stop moving when we expose them to specifically the berry vape. And really what we found was that the major movement that they were unable to do was to move from one alveolar space into the other, when we take in berry vape.
Chris - Do you think this is going to have functional consequences? In other words, were those mice to then be exposed to potentially infecting agents or other kinds of nasties from the environment that those macrophages would help to clear the fact they're paralysed or stuck in situ? Would that you think lead to these mice being much more susceptible to lung problems?
Ajitha - Oh yeah. So that's what we found. We gave them some bacteria and we found that the alveolar macrophages weren't able to get to bacteria that landed in an alveolar space that was next door that didn't have a macrophage in it. So this inability to squeeze to the next alveolar space, inhibited them from clearing that bacteria. And this resulted in more bacteria growing inside that berry mouse and the mouse not doing as well.
Chris - What do you think the mechanism of this is? What's the chemical that's doing it and can you recreate the effect by just providing the chemical in the vape in isolation? Can you paralyse macrophages that way to prove that it must be the chemical in the vapour? Or are there several things happening which culminate in these macrophages not doing their job properly?
Ajitha - You know, Chris, science is never black and white and so that's what we figured out. So we actually did all these fancy techniques and we took our berry e-cigarette vape and we figured out all the different chemicals in it and we isolated those chemicals and then we gave animals these individual chemicals. And it didn't have the same effect as the combination that blocked the alveolar macrophage function. So it really had to be all of these complex chemicals going in at the same time. And individually it didn't have an effect. And we actually tested one other flavour, because I didn't want to go down the garden path of testing every single flavour out there, but we kind of stuck to the chemical composition of different flavours. And we tested something that was very different from Berry, which was menthol, and it didn't inhibit alveolar macrophage behaviour.
Chris - What are the implications then in your view of what you've found?
Ajitha - I think that we've seen, and in many places including the province that I'm in right now in Canada, that flavours are probably not a good idea to have in e-cigarette products. And we need to be careful about the types of flavours that we're including in these products and they can have detrimental effects. And I think that's really the take home message, especially some of these vaping products are marketed for kids, like the way they're sold, the type of containers are sold in, it's very colourful and it's really attractive to children and this can be a really bad thing for our future. So I think that's really the take home message.
08:58 - Ancient cheese found smeared on Chinese mummy
Ancient cheese found smeared on Chinese mummy
Emma Pomeroy, University of Cambridge
To China now, and the discovery of the world’s oldest cheese. Scientists believed that a ‘Caerphilly’ preserved substance dating back 3600 years that they found smeared on the heads and necks of mummies in the Tarim Basin was a dairy product, but it wasn’t until recent advancements in DNA analysis that they were able to say for sure that they were working with kefir cheese. And sequencing the bacterial genes in the kefir grains - which fermented the ancient milk into cheese - has revealed how they have evolved to become better cheese-makers over the past few millennia. The University of Cambridge's archaeologist Emma Pomeroy is an expert on our ancient ancestors and looked at the study for us. As it turned out, the very mummies mentioned in the study were what inspired her to follow the career she subsequently has!
Emma - The mummies described in this study, they come from what's now northwest China. It's called the Tarim Basin. It's part of the Taklamakan Desert. And they're actually quite famous mummies. They're naturally mummified bodies from the Bronze Age. So we're talking about 3,500-4,000 years ago. And they're a population that I heard about when I was quite young. I remember watching a documentary about them and being really excited just by the richness of the culture. So because of the way the bodies were treated once they died, they were put in some kind of coffins, which were then sealed over with cow hides. This has helped preserve not only the bodies but also the clothes they're wearing. So they've got these amazing kind of felt hats and feathers and little booties and things like that. Really fantastic. Interesting too, because as a people they look different to what was expected for that part of China. So a number of the individuals have quite European looking features, perhaps even blonde hair, and were a bit taller than some of the other surrounding populations. So from that point of view, they've been a bit of a mystery and genetic evidence has actually suggested now that they descend, so they're kind of a remnant, of a very ancient kind of Pleistocene , so ice age, population from North Eurasia who actually have very few descendants now. But even at that time they were kind of a pocket left over of people descended from those ancient populations who were different from the other ones surrounding them.
Chris - They didn't migrate in later and established a pocket in the surrounding population. They were there first and got surrounded by what we would call more modern Chinese populations then. So they were there first.
Emma - That seems a very plausible scenario. It seems like the populations that were originally in that very broad area of ancient North Eurasia were ancestral to these populations.
Chris - So these dairy products that they were involved with, why did they end up on the mummies?
Emma - That's a really good question and I think 'we don't know' is the answer. So it's really interesting the sort of chunks of this kefir cheese kind of around the neck and the head area, why it would be there is really hard to answer. And there's a bit of a standing joke in archaeology that if we can't sort of say what something is for, we just say, 'oh well that's ritual.' And possibly that is, I mean sometimes when there isn't a practical explanation for something, symbolic activity, so a meaningful activity that's not necessarily got a functional purpose to it but has some meaning for the population, perhaps in the way they culturally believe you should treat the dead. That's where the behaviour comes from. It's not to say though that every day things that we do don't have a ritual element as well. You think about sort of how we eat, we use certain implements, we lay the table in a certain way. And that all is a kind of ritual in itself. So things can be functional and ritual at the same time. But in cases where we can't see something clearly functional, it suggests that it's something cultural and symbolic.
Chris - And how have the team that have been studying these mummies, how have they pursued this investigation of the cheese?
Emma - What they've done is they've taken small samples of the cheese itself and they've been able to sequence DNA from the bacteria and from the fungi, and actually even from the animals who produce the milk that the cheese was made out of to be able to tell exactly what it is. And from that they can tell that it is kefir cheese. So when you make kefir, the particular kinds of bacteria involved are different from making other kinds of yoghurt or dairy products. Um, and so they can say that this was kefir that's then been made into cheese.
Chris - And does this therefore give us insights into their husbandry techniques, the sorts of animals they had in what sorts of numbers, how genetically diverse even their herds were? What can we learn from that DNA evidence?
Emma - It helps to support some of the other evidence that we have about their lifestyle. And we can see for example, that they're using both goat's milk and cow's milk to produce the kefir. But usually not mixing it together, which is really interesting, you make it from one or the other, we can then see that they are herding and keeping these animals to be able to have access to that milk. And that fits quite well with the other evidence we have. So things like the animal bones that have been found, the cow hides that have been used to produce the burials, some of the clothing and things like that. So what we've built up is a picture of these as sort of nomadic people who are herding extensively. We can also say a little bit about where those herds originated from. So where did those animals originally come from? And we can say that that's likely to have been in the Caucasus, essentially.
Chris - This is being dubbed the world's oldest cheese, it's the oldest surviving specimen. Do we think this is really some of the earliest examples of making cheese or were people probably doing that for much longer?
Emma - We have good evidence that people were actually making cheese for substantially longer. But this is exciting because it is the cheese itself, which is really remarkable and a rare preservation. But for example in Europe we have evidence that comes from pots, say, from ceramic and they've analysed the tiny traces of the substances that were in the pots that have kind of soaked into the ceramic. And from that they've been able to isolate proteins that come from cheese and those data about 7,000 years ago or so. We have evidence from South Asia as well for sort of early cheese making. But yeah, this is perhaps with some from ancient Egypt, some of the earliest actual cheese itself, which is amazing.
16:09 - Are Naked Clams the future of food?
Are Naked Clams the future of food?
David Willer, University of Cambridge
We saw a story about a Naked Clam and thought it would be remiss of us Naked Scientists not to “cover” it. The researchers have been developing a way to grow these bizarre organisms, which can apparently eat their way through an oak beam and sink a ship in under 9 months, as a possible source of food. They’ve also been using artificial intelligence to analyse social media to explore the appetite consumers might have towards eating these bivalves. Supposedly, they’re delicious, and most people decide they like them! Cambridge University’s David Willer explains more…
David - Something sunk Columbus' ships when he was sail around the Caribbean in the 1600. And that something is actually a type of clam, which instead of having a shell eats and burrows into wood. These things can reach up to two metres in length. They're huge. We dub this 'the naked clam', also Teredinids that's the kind of scientific name.
Chris - When you say they're naked, that's no shell whatsoever? So are they a clam that's lost their shell at some point then, or did they just never have one? Are they the sort of clam equivalent of a slug versus a snail?
David - Take Nearly Headless Nick from Harry Potter. They've nearly lost their shell. But what's actually happened is the shells evolved into two big boring drills which allowed them to drill into the wood and actually inspired the drilling machines for the channel tunnel.
Chris - Where did they actually come from then, because obviously ships are a fairly recent phenomenon, did they eat wood that fell in the sea then? Is that where they would've evolved this behaviour?
David - Naked clams naturally would consume wood degrading in the sea. They're often found in mangroves actually, where they'll eat mangrove wood. So if you go out to the Philippines or Thailand, you will find people who've consumed them for thousands of years and harvested them from the mangroves.
Chris - Wow. And what was the question you wanted to know about them, apart from the fact that they look like they sank Columbus' ships?
David - Well, the key thing is that recently we designed the world's first lab scale naked clam aquaculture system. But any new food solution is useless if no one's actually going to eat the animals. So we wanted to understand, are people going to eat a naked clam and will they enjoy the taste of it?
Chris - First of all, tell me what does that aquaculture system involve? You basically just chuck bits of wood in a swimming pool and they grow. Is that the idea?
David - Our concept is actually something like a shipping container when we scale it up, where you put wood in, you farm the naked clams, and you get a nutrient packed protein source coming out the other end.
Chris - So you just eat the clam, that's the idea. Or do you turn them into something else?
David - You can eat the clam or you could process it into fish fingers or fish cakes.
Chris - And what does it taste like?
David - They taste like oysters. But, like a whiskey tastes a bit like the wood you've held it in, The flavour of a naked clam is influenced by the wood you grow it in. So something grown in oak is different to something grown in teak or something grown in pine.
Chris - Now two of those woods are hard and valuable. Pine's a bit cheaper. Is this something we could do sustainably?
David - Our concept aims to use waste wood from the forestry industry, so the kind of chippings off the forest floor. And we're working with pine at the moment.
Chris - Okay. So how does this actually work then? I know you said you've got a shipping container, but what's the throughput? How long do they take to rear? Is this actually practical?
David - Currently we're running a lot of scale up work in our labs. We're targeting a six month production cycle. So six months from, from your juvenile to a larger individual, around 30 centimetres in length.
Chris - That's quite fast growth.
David - It is fast growth. They are the world's fastest growing bivalves. There is a lack of data on that. We are trying to get some really good numbers on that data.
Chris - And are they good for you? As in, do they contain various nutrients that, if you eat this, you're not having to eat salmon and so on because you want some oily fish and so on. Can they substitute for other rarer things that we're currently decimating the oceans to get?
David - They are nutrient rich. We've done the world's first nutrition analysis on them. They've got more B12 than muscles, which already are renowned as a B12 source. They're high in protein, and because they feed on algae too, you can fortify them with extra Omega-3 by providing them with algae. But it only works if people eat them.
Chris - And what does the research suggest and how did you do that to find out?
David - We decided to leverage AI. It's a hot topic, but actually it can be really useful. And what we did is we analysed all the videos and comments and likes across the big social media platforms. And what we found was really interesting. Whilst before trying naked clams, it was about 50/50; half of people thought they liked them, half people thought they wouldn't like them. Once people had tried them, about 84% of people liked naked clams. And that's really key because that tells us that if you can get people to overcome that initial hurdle of trying a new sustainable food, it can go a long way to driving change.
Chris - Were these ate raw? I mean, how do you prepare them and do you think you're looking at a subgroup of people who are ambitious and willing to try something a bit novel and your average person, if you went to an average person in the street with a plate of these things, they would just say no thanks.
David - So there were a variety of recipes ranging from raw to naked clams, battered a bit like calamari, to marinated dishes and stews and curries. So a big variety of dishes which do suit a variety of tastes. One thing worth adding in is that we did get the Financial Times actually to pull together a set of recipes and we got one of them cooked out in the Philippines by my student's mum, who cooks them regularly for dinner. That was fantastic, you know, tasted lovely.
Chris - And one other practical question. When we try and do mass scale production of this kind of thing, we force lots of animals to grow in a small space. It's intensification, isn't it? Inevitably diseases emerge, parasites creep in, viruses crop up that can begin to decimate crops and so on. How do you keep them safe so they don't succumb to those kinds of threats?
David - The key thing here is controlling the colonisation of the wood. If you have lots of larvae in a tank, colonising wood, you want to ensure a certain number settles. And that's where actually the wood matrix design we've got for farming them is so important. So it's a patent pending system which ensures you just get a small number of individuals colonising the wood, so you get fewer big individuals rather than an over colonisation.
22:41 - Earth to gain temporary second moon
Earth to gain temporary second moon
Matt Bothwell, University of Cambridge
You may have read or heard in the wider media that the Earth has allegedly acquired a “new Moon”. Well, ish. We’ve certainly picked a new satellite, of sorts, but it’s a bit of a giant leap to say this lump of rock is going to give our mainstream moon a run for its money. Here's Cambridge space scientist and “public astronomer” Matt Bothwell to clear things up for us…
Matt - So the object is the very imaginatively named 2024PT5 in the long tradition of fantastic, memorable astronomy names. It's a near Earth orbit asteroid. So it's a piece of rock, something about 10 metres wide, which is orbiting the Sun. And on the 29th of September, it's going to get close enough to Earth that it's coming into our gravitational sphere of influence and is going to start sort of orbiting the Earth. And so this is where it hit the news, right? We are going to have something orbiting the Earth. It's gonna be a new mini moon, but it is a little bit more subtle than that. So really to be counted as a temporary satellite, you have to do one orbit around your planet? At least go once round. And this thing's not going to make it all the way around. It's going to do a sort of horseshoe shaped slingshot around the Earth before heading off into deepest space. So we are going to get a temporary fly by companion, but it's a bit of a stretch to call it a temporary moon.
Chris - How far away will it pass?
Matt - It's going to be about five times further away than the regular moon. So the regular moon is 300,000 kilometres. This thing's closest approach is going to be about one and a half million kilometres. So it's not nearby by any stretch of the imagination.
Chris - Visible or not?
Matt - Absolutely not. Unless you have a sort of multi million pound telescope. I think even a very, very big backyard telescope won't be able to pick this thing up. So unless you have access to a professional astronomy telescope, I think your chances are slim.
Chris -
How did it get detected then if it's quite hard to spot? It's quite small. How did scientists spot it in the first place?
Matt - Scientists have programmes to detect near Earth asteroids because there's always a risk that might be dangerous. So we have catalogues of hundreds of thousands of things going all around our neck of the woods in the solar system. And so this was just picked up as part of our regular searching of the sky for anything that might come near us and be potentially hazardous.
Chris - No risk that that might happen.
Matt - No risk whatsoever, no. This thing is going to do a little loop around us at this very safe distance of one and a half million kilometres and then carry on its merry way.
Chris - And if it were on a collision course with the Earth, would it be consequential to something that's that size about 10 metres across, or is that too small to even notice? Would it even make it to the ground?
Matt - Yeah, this is far too small to be a problem, even if it did hit us. In order to be at risk to something like a city, you need to be a couple of hundred metres across. I think something like this would cause a spectacular fireball and probably not make it all the way to the ground. So even if it hit us, we'd be safe, but it's not. So there you go.
Chris - Can we get any clues from its path and trajectory where it might have come from? Where do scientists think its origin was?
Matt - It's a difficult one to say definitively, but I think there's a strong clue that it might be a piece of the Moon, what scientists call lunar ejecta. When we look at its path around the Earth doing it's like a near Earth object thing, it's moving as if it was once ejected from the surface of the Moon. So this could well be the remnants of a meteor strike that hit the moon billions of years ago, threw up shards of rock. And this thing has been orbiting around for billions and billions of years.
Chris - Has this sort of thing happened before or is it a one off?
Matt - It has, it happened semi-regularly. There was something in 2022 and in 2020, that was very similar to this. The last time we actually got a proper temporary moon was in 2006 when a near Earth object came and spent about a year orbiting around the Earth before zipping off. So yeah, every few years something like this does happen.
Chris - How can that happen then? How can something temporarily orbit and then disappear again? Is it on a sort of expanding orbit or something, so it's sort of captured for a while and then eventually gets lost? How can that happen?
Matt - Yeah I think captured for a while and then eventually gets lost is a good way of putting it. Orbits have to be very, very exact to be what we call stable, so that they can exist for thousands or millions or billions of years. In the case of our solar system, you have to have a very, very exactly precisely correct amount of energy to be in a stable orbit. Ever so slightly either side of this, exactly like a bullseye amount of energy, and you can be temporarily captured, but then either fly off into space or fall down onto Earth.
Can dead animals contaminate our food?
Thanks to Malcolm Bennett for the answer!
Malcolm - I think this is, like all great questions, simple to ask and maybe not quite so simple to answer. If there is a simple answer, I guess it's probably 'yes, but...' So let's deal with the yes part first. Of course, lots of the food you eat will have been in direct or indirect contact with dead animals, dead invertebrates, dead small mammals and birds, and of course poo, which if it comes from a carnival or an insectivore is a kind of processed dead animal. And the microbes involved in decay are usually not pathogenic. That's to say they don't usually cause disease. And most of the pathogens in the corpse, if they cause the death of the animal for example, will die by the time your vegetables have grown because they, they don't really survive in the soil. Furthermore, these bacteria and their toxins are rarely, in fact, I can't think of any examples actually taken up by the roots of plants. The first really big but is if the animal died of anthrax. So the bacteria that cause anthrax can survive in the soil for tens, maybe hundreds, of years. And when exposed to air, they form spores that readily form aerosols and you breathe them in and they can kill you. In somewhere like the UK, anthrax, which is usually seen in farm animals, has always been pretty rare. So anthrax would still not be taken up by any plants that grew in that soil, but I suppose you could get it, for example, from digging potatoes somewhere which was contaminated maybe a long time ago. So nobody even guessed the place was contaminated. The other 'but' is to do with water contamination. The chemicals released from a rotting body can get into water. And some of these might contain or encourage the growth of bacteria which produce toxins, which wouldn't be very good for you. And at the very least, taint the water's taste. And that in turn leads us onto the law, which is quite big on this. In most of the uk you can bury small pets in your own garden, but it has to be your own garden. It has to be your own land. You can't bury them in a local park and you can't bury them in your neighbour's garden. So if I go back to the beginning, I think my conclusion is still that the answer is 'yes, but...'
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