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Interviewer: Charlotte Stoddart
Hello and welcome to the Nature Podcastwhere this week we’re delving into the hot new field of single cell biology. It’s a bit like a fruit salad.
Interviewer: Shamini Bundell
Mmm, tasty. We’ll also be hearing how studying tiny shells, the size of sand grains, is helping us understand sea level rise.
Interviewer: Charlotte Stoddart
This is the Nature Podcastfor July 6th2017. I’m Charlotte Stoddart.
Interviewer: Shamini Bundell
And I’m Shamini Bundell.
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Interviewer: Shamini Bundell
First this week, reporter Anand Jagatia finds out how researchers are taking Quantum computing to the next level. Move over qubits, get ready for qudits – with a ‘d’ – a next kind of quantum bit that can store even more information. But first, a reminder of how information is stored in qubits.
Interviewer: Anand Jagatia
Unlike classical bits which store information as either zeros or ones, qubits can exist as both zero and one at the same time – a property called superposition. I’ve never really understood how this is possible, but physicist Michael Kues from the National Scientific Research Institute in Canada, told me it’s a bit like flipping a coin.
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Interviewee: Michael Kues
So you can think of a coin that has heads and tails and if you throw it in the air, it’s rotating and you don’t know what state it is and if it falls on the ground… [Coin flipping sound effect]…then you measure it and then it’s either heads or tails but if it’s in the air it’s actually in the superposition of both.
Interviewer: Anand Jagatia
Because qubits can exist in 2 states at the same time, quantum computers can be used to perform many calculations simultaneously, exponentially faster than classical computers. But it’s actually possible to create quantum systems that exist in more than 2 states at once: for example, a qutrit can be in three states simultaneously. But why stop there? In a Naturepaper this week, Michael Kues and his colleagues have built a system that can create even higher dimensional quantum states.
Interviewee: Michael Kues
So in our system we actually managed to generate a qudit, so that’s a high dimensional quantum bit and it can be in a state zero and one and two and three and so forth. In our research we used photons – so the quantum of light – and we actually used the colour of the photon which means that the photon can be red, green, yellow and blue at the same time. And only if you measure it can you actually define the colour.
Interviewer: Anand Jagatia
Going back to the coin analogy: using a qudit is kind of like throwing a many sided di into the air, with each side painted a different colour. Well actually it’s more like throwing two of these dice up in the air, that are intimately connected to each.
Interviewee: Michael Kues
We actually not only create one photon with this but we create entangled photons that are kind of linked to each other. If the first photon is in the state zero, imagine the state zero, the second photon is also in state zero but this again then with colours.
Interviewer: Anand Jagatia
In fact, these qudits can be all seven colours of Newton’s rainbow at once, with room to spare.
Interviewee: Michael Kues
So in our case we demonstrated the maximum number of 10. So it can be in ten states but you can actually scale those up, maybe with state of the art devices of today. We could go to one photon having already 100 dimensions because we look at two photon systems that would already correspond to 10,000 dimensions, so 100 times 100.
Interviewer: Anand Jagatia
The system works by shining a laser into a special ring called a micro-ring-resonator which is inside a photonic chip.
Interviewee: Michael Kues
From the laser that you shine in the ring, you take two photons and they are annihilated and two others are created, red and blue, let’s say, but then again in the superposition of these many states. After that we have already generated the state, this entangled state, but we need to actually prove that it’s an entangled state and for this we developed another set up that is based just on telecommunication components to analyse the state and actually show that it is this high dimensional and entangled quantum state.
Interviewer: Anand Jagatia
So why is it better to have one qudit that can be in many states at once rather than having lots of qubits?
Interviewee: Michael Kues
So in photonics, if you have many photons in just two states then you need to detect the state. So, if you just lose one of these many photons then you actually cannot detect the state anymore but if you encode the same information just in two photons that have high dimensions then the losses do not kick in so much, so you can actually increase the amount of information you put in just one photon and increase the detection rate of the photon.
Interviewer: Anand Jagatia
This system for generating qudits could be useful from a fundamental physics point of view, allowing researchers to study higher dimensional quantum states in more detail, or run quantum simulations. But photons are also perfect for transferring quantum states over long distances. In the paper the authors manage to send their qudits a distance of over 24 kilometres using a fibre-optic cable. I asked Michael what he thought this research could do for the field of quantum technology.
Interviewee: Michael Kues
Qudits have been shown before already in very complex systems in photonics but we have here actually a very easy and compact system that is on a computer chip, and very scalable. We have manipulation schemes that are based just on telecommunication components which are easily available and also very cheap actually so we can now exploit all these devices for these quantum systems and that’s very interesting, I think, and very exciting.
Interviewer: Shamini Bundell
That was Michael Kues from the National Scientific Research Institute in Canada talking to Anand Jagatia. There’s also a News & Views article about the study at nature.com/nature.
Interviewer: Charlotte Stoddart
Later in the show we’ll be hearing about ice loss in Greenland in the Research Highlights and how more ice loss, this time in Antarctica’s past, is helping us to understand sea level rise.
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Interviewer: Shamini Bundell
This week’s Natureis a special issue. We’ve got an editorial, a comment piece, three different features and several other bits and bobs all talking about one hot new field of research: single cell biology. Now, you might not know what that is.
Interviewer: Charlotte Stoddart
Is it the biology of single cells?
Interviewer: Shamini Bundell
Well, yes.
Interviewer: Charlotte Stoddart
But haven’t we been studying single cells for hundreds of years?
Interviewer: Shamini Bundell
Yes, well – also yes – but that was using microscopes. These days molecular biology is concerned with things like DNA and RNA and proteins, working out which genes are active in which cells when and that kind of thing. And most of that work hasn’t been done on individual cells until very recently. And that’s what people are calling the single cell revolution. One of this week’s features has been written by our very own Ewen Callaway so I dragged him down to the studio to ask him about the topic, starting with an obvious question: if we haven’t been studying individual cells all this time, what have we been studying?
Interviewee: Ewen Callaway
Well, we’ve been studying large numbers of individual cells, and so if you want to study the heart or something like that, you’ll take a chunk of heart and pulverise it and extract the molecules from that and study those. You may be studying molecules from millions if not billions of cells and a really good metaphor that I’ve heard is that it’s kind of like a fruit smoothie that has maybe got a few blueberries in there but if it’s got a lot of banana and a lot of strawberry, those are the flavours you’re going to taste. Whereas single cell biology… what people are doing is more like a fruit salad, so, you can pick out that one or two blueberries and you can taste it. So that’s what researchers are doing now. They’re able to study fruit salads and in so doing they’re realising that to continue this maybe rather strained metaphor, that not all blueberries are the same.
Interviewer: Shamini Bundell
So, previously what we were doing was averaging out a bunch of cells that we assumed were the same?
Interviewee: Ewen Callaway
People maybe appreciated that there might be differences and I think there would have been tantalising hints but the technology just hasn’t been there to easily separate single cells and then certainly not to study the molecules in each Individual cell and make sense of differences.
Interviewer: Shamini Bundell
So this is a technological development from the last five years-ish?
Interviewee: Ewen Callaway
Yeah, five, ten years. But I think the coming decades we’re going to see some real surprises from studying single cells.
Interviewer: Shamini Bundell
What kind of things have we learnt so far from studying single cells that we didn’t get from studying them on mass?
Interviewee: Ewen Callaway
I think one of the biggest and earliest pay-offs has been this realisation that even though cells look alike, they’re completely different and that might be really important to disease. Some researchers recently identified immune cells that are in the brains of mice that I think could be linked to diseases such as Alzheimer’s and they’re present at such vanishingly small levels that you would never see them without these techniques.
Interviewer: Shamini Bundell
And because this technology has only been around for the last few years, how big is this field currently and what kind of different areas are people looking and making progress in?
Interviewee: Ewen Callaway
It’s probably getting bigger all the time. Flipping through an issue of Natureor a conference abstract section, you see there are fewer areas of biology that aren’t being touched. Cancer biology is one area where I think single cell biology is really set to make a big, big impact because most people think that cancer develops when one single cells acquires a mutation that sends it down a path, all the while acquiring more and more mutations, and for the longest time I think people have studied tumours and tumour evolution as this mass of cells but what if you could study them one by one? Maybe you could catch the cells that are on their way to becoming metastases. So that’s the kind of stuff that people are getting really excited to do.
Interviewer: Shamini Bundell
And this being such a popular growing area of science – there’s also some big multi-disciplinary, multi-institutional projects that are getting going about now, aren’t there?
Interviewee: Ewen Callaway
Yes, super projects. Biologists love a consortium. I think the big one around single cell biology is this effort called the Human Cell Atlas project and their idea is to take the trillions of cells in the human body and see if you can characterise every single different cell type.
Interviewer: Shamini Bundell
And that’s probably going to reveal a lot of new cell types and potentially new cell states. I actually rang up one of the leaders of the Human Cell Atlas project earlier today, Sarah Teichmann, and she was telling me why this is so important.
Interviewee: Sarah Teichmann
So, I’m excited about even the basic biological insights actually, and having a deeper understanding of our tissues, our organs and our bodies, but clearly there are massive medical and translational applications, ranging from biomarker discoveries to drug target discovery, to understanding toxicity. This isn’t a small task so it’s going to take – even achieving a first draft will probably take on the order of a good five years or so. Watch this space.
Interviewer: Shamini Bundell
Ewen, what do you think about the scale of this project to try and map every cell in the body?
Interviewee: Ewen Callaway
It’s ambitious to say the least. We don’t know how many different kinds of cells we have. We have trillions of individual cells. I don’t think they’re going to pretend to be able to characterise every single one of those, but yeah, this is big biology.
Interviewer: Shamini Bundell
And is this single cell biology revolution, that’s terribly trendy at the moment, is it going to fade out? Are we going to find out everything we need to know and move on to something else?
Interviewee: Ewen Callaway
No, I don’t think it’s going to fade out because imagine studying astronomy without telescopes. You know, obviously you get bigger and better telescopes and different telescopes and telescopes that go to space but that tool has remained and these single cell techniques are allowing people to see new galaxies and things they never could have imagined, so no, I don’t think it’s going anywhere. I think it will be refined but I think every biology lab in the world is eventually going to become a single cell biology lab.
Interviewer: Shamini Bundell
That was Naturereporter Ewen Callaway. His feature is part of this week’s single cell special issue, on the web at go.nature.com/singlecell. You also heard from Sarah Teichmann of the Sanger Institute in the UK.
Interviewer: Charlotte Stoddart
Now, time for the Research Highlights.
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Interviewer: Charlotte Stoddart
It’s well known that the Greenland Ice sheet has been shrinking since the mid-1990s, losing mass as the surface melts and icebergs carve off into the sea. Previous studies have suggested that the surface melting is mainly due to the atmosphere heating up, but researchers have recently been looking at a different culprit: sunshine. A new paper shows that summer cloud cover over Greenland decreased between 1995 and 2009 by nearly 1% per year. That’s enough extra sunshine to melt tens of giga-tonnes more ice than in cloudy weather. As with the warming atmosphere, these weather changes seem to be linked to global warming. Find out more in Science Advances.
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Interviewer: Shamini Bundell
Horses are thought to have been domesticated from their wild ancestors several thousand years ago but recent research reveals that most modern horse breeds are descended from horses brought to Europe in only the last 700 years. The study looked at mutations on the Y chromosome to find out how stallions were moved around and bred to create modern breeds. Two major genetic sub groups were found: one from the Arabian Peninsula and one from the central Asian steps. Almost all European horses descend from these two, apart from certain breeds such as the Norwegian Fjord horse and the Shetland pony which branched off earlier – around 1,300 years ago. That paper is in Current Biology.
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Interviewer: Shamini Bundell
Next, Adam Levy takes a look at Antarctica’s past.
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Interviewer: Adam Levy
Marine biologist, Claus Dieter Hillenbrand, has been visiting Antarctica for over two decades. Part of the appeal is that the southern tip of the world is one of the few places where you can still feel like an explorer.
Interviewee: Claus Dieter Hillenbrand
During my first expedition in ’94, we discovered a new island which was very small but where can you do something like that on earth these days?
Interviewer: Adam Levy
There’s still lots to learn about Antarctica and that knowledge is key to understanding how seas will rise as the planet warms. As we’ve discussed previously on the podcast, there are wide ranges of model predictions for the Antarctic’s contributions to sea level rise, in part due to uncertainties about which physical processes will take place. One way of pinning down what might happen in the future, is to look into the past. That’s exactly what Claus Dieter has done in a new study which looks at how one ice sheet varied over the last ten thousand years. He joined me in our studio in London to discuss the new work. But first I asked what the most important drivers of the ice loss are in Antarctica.
Interviewee: Claus Dieter Hillenbrand
The most important factor, as has been shown over the last 20 years or so, is oceanic warming actually: so the warm ocean water which is actually melting very efficiently, the floating parts of the ice sheet and where the ice sheet actually meets the ocean.
Interviewer: Adam Levy
You mention that a lot of this issue is from warm water melting the floating part of the ice, but the floating part of the ice itself won’t necessarily contribute to sea level rise because floating ice, when it melts, doesn’t really raise the seas.
Interviewee: Claus Dieter Hillenbrand
Yes, exactly.
Interviewer: Adam Levy
So why does that actually matter?
Interviewee: Claus Dieter Hillenbrand
The problem is that the floating parts of the ice – the so-called ice shelves – they are buttressing the ice in the hinterland. Ice shelves have collapsed in the 1990s and the early 2000s. After they had collapsed what happened was that the ice sheets in the hinterland were actually accelerating their flow and this is the mechanism which is so important for our current and our future sea levels.
Interviewer: Adam Levy
So that is something that we know has happened in the recent past. But you guys wanted to see whether it had happened in a similar way in the more distant past?
Interviewee: Claus Dieter Hillenbrand
Exactly.
Interviewer: Adam Levy
And how do you begin to look at that before we had satellites, before people were on Antarctica? How do you unpick that kind of thing?
Interviewee: Claus Dieter Hillenbrand
So, before any man set his foot onto the continent, the only way is to look into the climate archives. I’m a marine geologist so naturally what I’m looking at is the rackets on the sea floor. What you see is actually deposits left by the ice sheet in the past, on the continental shelf, when the ice sheet was more expanded in the past. To date them, what you have to do is then to collect sediments and we have done that, for example, for the Amazon sea which is the sector where we have the most dramatic changes today and got quite a good idea of how far expanded the ice sheet was during the last ice age, so between about 18,000 and 12,000 years ago.
Interviewer: Adam Levy
I can see it as fairly intuitive that you’d be able to reconstruct what the ice was doing at various points in time but understanding what warm water was doing over the distant past seems like something that would be quite a lot harder to do.
Interviewee: Claus Dieter Hillenbrand
What we need to look for there is actually looking at the remains of organisms which were living on the sea floor. So, very important for us are carbonate shells which are unfortunately very rare. However, geochemical analysis of these shells, they give us a clue about the properties of the waters which were present at the time when these organisms lived there. So we can establish a timeline of what the water was doing at particular time periods. It’s not easy because these shells are very, very tiny.
Interviewer: Adam Levy
And how rare and how tiny are these things?
Interviewee: Claus Dieter Hillenbrand
If you think of just sand – usually they are sand-size, but they are extremely rare. We have sediment cores which are ten metres long and we sifted hundreds of samples and didn’t find any of them.
Interviewer: Adam Levy
But once you’ve collected these shells you now have two data sets: one which is showing how big the ice sheet was at different times and one showing when there were these warmer waters. Does looking at them confirm that the warm the water was linked to shrinking the ice sheet? I know that’s something that models simulating the last ice age have suggested should be the case.
Interviewee: Claus Dieter Hillenbrand
So, yeah what we have done, it was first set, that really when the ice sheet retreated, when we had these warm water incursions and we could show that this mechanism was the dominant mechanism in driving ice sheet retreat during the last twelve thousand years and the very end of the last ice age.
Interviewer: Adam Levy
I know there’s a lot of disagreement in projections about what’s going to happen in Antarctica over the next hundred or hundreds of years.
Interviewee: Claus Dieter Hillenbrand
Exactly.
Interviewer: Adam Levy
Does this help tie that down and help us have a bit more certainty about what might happen over the coming decades.
Interviewee: Claus Dieter Hillenbrand
Yes because we know the driving mechanisms – the main drivers for ice sheet retreat. The next step would then be really to get numbers for these warm water incursions so that we know how warm the water was, that we then can use for the future predictions. We really need to know what will affect the ice sheets in future and how it will influence our lives as humans on earth.
Interviewer: Shamini Bundell
That was Claus Dieter Hillenbrand who’s based at the British Antarctic Survey in Cambridge. For more on researchers’ efforts to predict Antarctica’s future, check out the episode of the Nature Podcastfrom the 31stMarch 2016.
Interviewer: Charlotte Stoddart
Time now for the News Chat and Richard van Noorden has joined us to talk about a report out this week on EU funding. What does the report say Richard?
Interviewee: Richard van Noorden
So this is an influential report about Europe’s next massive science funding programme. And when I say massive, these are ginormous things. The current seven year research funding programme of the European Union is 75 billion Euros. It ends in 2020 but scientists already want, obviously, more money. But also they have a love-hate relationship with these funding programmes. They’re very bureaucratic and the rules seem to change every single new funding programme but of course it’s nice to have the funding and the support of these collaborative projects across the European Union.
Interviewer: Charlotte Stoddart
So this report is calling for more money – perhaps not surprisingly – and less red tape. Who’s authored the report and how likely is it that they’ll get what they want?
Interviewee: Richard van Noorden
So it’s coming from a group of academic and industry experts at the European Commission, asked to give them its views on how EU research can have more impact, so it’s set to be influential. And they say that they want to double the European Union’s research budget, so that sounds great. And in this report, the head, Pascal Lamy – a former World Trade Organisation director general – he says that’s a bare minimum. So if the EU follows this, that’s fantastic. He’s basically saying that the EU as a block needs to invest more into research and he’s introducing this idea that the EU has an innovation gap with the United States, with South Korea, and it’s other trading partners. It is expected to be influential and insiders say it will be influential but whether politicians can really be persuaded to give such a price hike is yet to be seen. The commission won’t actually make a proposal for what this program will look like until the end of this year and then there’ll be a lot of discussion. And of course, this all plays within the uncertainty of what is the EU’s overall budget post-2020 because if the UK isn’t a part of it, the budget obviously comes down.
Interviewer: Charlotte Stoddart
Right, and with the UK outside the European Union, I guess that means that UK researchers won’t be eligible for this funding?
Interviewee: Richard van Noorden
Well, it’s all a question of how the UK negotiates its departure from the European Union. Could it continue to pay into aspects of the EU and have some sort of association with the program? Possibly not if it insists on not allowing the freedom of movement of researchers from EU countries to and from the UK. So, we’ll have to see but in this report, Lamy does say that full and continued engagement with the UK would be a win-win – and obvious win-win he says – for the UK and the EU, but I don’t know how influential his voice will be in the wider scheme of things.
Interviewer: Charlotte Stoddart
And the second story you’ve brought with you also involves politics. Scientists are worried about the supply on helium coming from Qatar. First, why is that supply being cut off?
Interviewee: Richard van Noorden
So, it’s a political story again. Saudi Arabia and other neighbouring countries have essentially been in a political dispute with Qatar over the last few weeks over Qatar’s alleged support for terrorism. They basically instituted a blockade of imports and exports and one of the things being blockaded is helium. Qatar now makes a quarter of the world’s helium production and it was supposed to be getting to a third by 2018, because it opened some new helium refineries but it shut them down because they can’t get their helium out so that is a rather sudden shock.
Interviewer: Charlotte Stoddart
And how widely used is helium, by scientists?
Interviewee: Richard van Noorden
So helium, uniquely, boils at 4 degrees Kelvin – unbelievable cold. Before that it’s a liquid so it’s used to chill superconducting magnets in things like MRI machines in hospitals and in research labs, and in NMR machines that chemists use to distinguish the structure of, say, crystalline materials. Now, in fact, labs account for only about 6% of the helium market. The major uses are in hospitals and the electronics industry, and also of course for air ships and balloons. Now that does mean that researchers are kind of bottom of the list. They’re not the major customers when there’s a sudden disruption in supply. And we talked to scientists who say yeah, we’re braced for shortages here. People are worried but it’s not like this hasn’t happened before. Helium supplies do get disrupted. So if this blockade continues then it could get rather concerning for scientists and some research projects will probably have to be stopped.
Interviewer: Charlotte Stoddart
Could scientists turn elsewhere for their supply of helium or even make it themselves?
Interviewee: Richard van Noorden
Well, helium – I mean, there’s lots of helium in the air but extracting it from the air is just an economic non-starter. It has to come from the crust and it comes out along with natural gas, so essentially it’s all up to whether big refineries who extract natural gas consider it worth their while to also sell on the helium that comes out with it and cool that and refine it. So it’s not really something that scientists can do by themselves. The US has a very large supply because the Apollo programme used helium to purge cryogenic tanks and lines in the Saturn V Rocket that was used to launch astronauts towards the moon in 1969. It’s built up this massive supply which it’s slowly selling off at quite low prices. So if you’re in the United States you might feel a bit safer, but all things’ll come to an end. Now attention is turning to helium recycling. Helium literally evaporates into thin air. It boils at this incredibly cold temperature. And that’s why it’s very hard to keep. It actually evaporates out of the world’s atmosphere and into space. So, lab facilities haven’t thought much about recycling or re-liquefying their helium. But it can be re-liquefied, stored and reused and it does cost quiet a lot for labs to put in this recycling technology. There are websites that allow you to calculate whether recycling will work for your institution, whether it will make economic sense and we have a leader that says this political unrest essentially underlines the need for helium recycling in science.
Interviewer: Charlotte Stoddart
Thanks Richard. You can read all those stories and more online at nature.com/news and if your lab will be affected by the helium shortage, we’d love to hear from you by email, podcast@nature.com, or on Twitter, @NaturePodcast.
Interviewer: Shamini Bundell
We’ll be back next week with more research revelations and science surprises. I’m Shamini Bundell.
Interviewer: Charlotte Stoddart
And I’m Charlotte Stoddart.
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