Cancer’s power harnessed — lymphoma mutations supercharge T cells

Benjamin Thompson

Welcome back to the Nature Podcast, this time: giving T cells an evolutionary advantage in the fight against cancer…

Nick Petrić Howe

...and the battery technology of the future. I’m Nick Petrić Howe.

Benjamin Thompson

And I'm Benjamin Thompson.

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Benjamin Thompson

Immunotherapy has revolutionized the treatment of certain types of cancer. One approach is to engineer immune cells like our own T cells to hunt out and kill cancer cells. You may have heard of CAR-T therapy, for example, which has shown great promise in treating some blood cancers but proved less effective at attacking solid tumours, like lung or liver cancer.

Jae Choi

For solid tumours, these cancers have evolved to create these walls that make it very difficult for the immune system to penetrate, survive and kill them.

Benjamin Thompson

This is Jae Choi a dermatologist and geneticist from Northwestern University in the US. He and his colleagues have been trying to find new ways to give T cells a boost and overcome these walls. And they’ve come across a rather unexpected way to do it.

Jae Choi

The way I got into this is actually I see all these patients with skin T cell lymphoma. And I've always just been thinking, like, why is it there? What are the cells doing?

Benjamin Thompson

Jae and his colleagues started looking at these lymphomas, cancers that affect T cells themselves, and asking how they are so persistent.

Jae Choi

And it turns out through the work that we've been doing for the last five to ten years, we've repeatedly seen, that these lymphomas actually have to overcome the same exact challenges that occur with T cells in the cell tumour microenvironment.

Benjamin Thompson

These T cell cancers have evolved mechanisms to overcome many of the challenges cancerous tumours create for our own immune system. And that gave them an idea.

Jae Choi

So, we hypothesize that evolution has given us a roadmap by which we can learn how T cells have been designed to overcome these challenges. And we can use the power of evolution to power next generation therapies.

Benjamin Thompson

Jae wanted to take the mutations that lymphomas have evolved and use them to his advantage — by inserting them into therapeutic T cells, thus empowering our own immune cells with the cancer’s capabilities. But with one big caveat.

Jae Choi

What we didn't want was a mutation that would be by itself able to cause cancer, that really didn't make any sense to us at all. So, all of our studies are really geared to find this safe, but supercharged T cell that can actually kill the tumour, and its home base, this solid tumour microenvironment.

Benjamin Thompson

So they searched for useful mutations which wouldn’t cause cancer, and it wasn’t just lymphomas they looked at.

Jae Choi

The vast majority of our work have come from these lymphomas, which are cancers. But actually it turns out many of these mutations are shared with T cells that happen to be in even autoimmune and autoinflammatory diseases. We were trying to highlight the fact that many of these mutations are not in and of themselves sufficient to cause cancer, because they can be found in patients where it actually doesn't turn into cancer.

Benjamin Thompson

The team identified 71 mutations that offered these cells an advantage and they introduced them into therapeutic T cells designed to target tumours. Then they assessed what effect the mutations had, both in a dish, and in in vivo mouse models. In particular, they were looking for cells that gained the ability to stick around, something that’s previously been an issue in solid tumours.

Jae Choi

For large part is these T cells don't persist in the patient or in the tumour. They may get there originally, they may cause some killing, but they're gone before you know it. So our first in vivo screen was actually looking for, can we find mutations to increase persistence in the tumour microenvironment. And then we want to look at the ability to recognize and kill tumour cells in vitro in vivo, because that would absolutely be needed for potential clinical products.

Benjamin Thompson

One mutation in particular seemed to fit the bill — a fusion between two genes, called CARD-11 and PIK3R3.

Jae Choi

So actually, what the fusion does is it eliminates the brake from CARD-11, which allows the CARD-11 to be stronger and active in more situations and actually to be active longer. And so it's been fused with another domain, PIK3R3, we don't really know what that does, per se, but we think that it allows it to bind to very desirable Protein-Protein binding partners, which enables for like a very unique Goldilocks-type signalling, which enables enough, but not too much signalling in our T cells.

Benjamin Thompson

It appears that these fused genes are able to activate biochemical pathways that are advantageous to T cells, and downregulate pathways that aren’t, giving them a boost when tested in mice.

Jae Choi

It created this profound ability to thrive in the tumour microenvironment, but then from this study, it turned out that we discovered that using even a small number of T cells we’re able to cause durable complete remission of very difficult to treat tumours in vivo in these preclinical models. And so we don't know exactly the mechanism, but it seems to get in better, it seems to thrive better in the microenvironment it seems to proliferate better, and it seems to kill better.

Benjamin Thompson

But despite these positive outcomes, there were cases when cancer came back.

Jae Choi

And we think that's because it absolutely relies on recognition of the antigen to be able to activate the pathways which enabled it to kill the cell.

Benjamin Thompson

T cells work by latching on to specific molecules called antigens found on the surface of cancers or infected cells. The team found that when the antigens aren’t present, perhaps when the tumour is destroyed or the antigens it presents shift, their fusion-equipped T cells don’t show the same abilities. And that can allow the cancer to return.

Jae Choi

So in some ways, it's disappointing because if we could solve all things and prevent cancer, you know, resistance, that'd be great. But also, it's another highlight of its potential safety that just couldn't do it an antigen is gone.

Benjamin Thompson

And safety is paramount with this approach, after all Jae and the team are choosing to take mutations which make T cell lymphoma better at being cancer, and then insert them into otherwise healthy T cells. And the last thing anyone wants is a therapy to treat, say liver cancer which ends up giving someone lymphoma in the process. And Jae is completely aware why this approach could be worrisome for people.

Jae Choi

I totally understand it. What I would say is just a couple things. Number one is that people have knocked out genes and not realise that they're actually tumour suppressors in T cells and given it to patients. And we have not really found a high evidence of this kind of manipulation causes lymphomas. Number two is that actually because it seems to really work optimally only when it has the cancer antigen, what we think is happening is that once the cancer is cleared, it should only be able to be maximally functional when the cancer is there for its express, you know, clinical purpose. So that's another safeguard which just happens to be part of the biochemistry of the molecule.

Benjamin Thompson

The team looked for any evidence of T cell lymphomas — in some cases looking in mice over a year after their cancers had been cleared – and they didn’t find any. In fact, they say that the populations of their fusion-carrying cells had dropped to less than 1% of the total T cell population. And yet, understandably, the safety of T cell therapies remains in sharp focus, especially at the moment. In January, the US Food and Drug Administration wrote to several manufacturers of CAR-T therapies, asking them to add warnings about the risks of secondary cancers to their products. These numbers are low compared to the numbers of people who have received CAR-T therapy, and an FDA spokesperson has been quoted in news reports saying, quote, “we would like to underscore that the overall benefits of these products continue to outweigh their possible risks,” end quote. Lionel Apetoh from Indiana University is an immunologist who works on boosting immune cells’ ability to fight cancer but wasn’t part of the research team. He also has concerns about therapeutic T cells transforming into secondary cancers, especially when it comes to scaling up a therapy.

Lionel Apetoh

The difficulty is the numbers game, poor choice of word because it's not a game. But the thing is testing it on a few patients and seeing like the T cells can be there for ten years, it's already like a major achievement. But now, making sure that if you treat hundreds, or thousands of patients, making sure that those cells they persist, and making sure that they are not getting transformed is a major, major challenge. Because even if a tiny proportion of patient experience issues, that is of course devastating and that is the reason for these investigations.

Benjamin Thompson

Jae is thinking about further safety precautions for his fusion T cells, like adding molecular switches which would allow them to be turned off if something goes wrong. But there is a lot more work to do beyond that. Lionel was impressed by Jae’s choice to use only one fused mutation which is likely to reduce the risk of secondary cancers developing, although it is still not without risk.

Lionel Apetoh

That has to be taken with caution, because sometimes it's true that even a single mutation can drive transformation. But if that mutation is in normal cells, and using the strategy they used, I think it can be really an approach that can be tested, and actually they ensured about the safety in multiple ways, like they transferred the cells, they waited more than a year. So keeping in mind that they work with mice and the mouse lifespan is usually two years and they didn't see any transformation or any secondary cancers.

Benjamin Thompson

Lionel thinks there’s still a lot to learn about exactly what the fusion gene is doing in different types of T cells. And Jae and the team are keen to learn more about the mechanism through which their powered-up T cells are killing tumours so efficiently. And of course it remains to be seen whether their lab results will translate from mice into humans. But Jae thinks that the approach they’ve taken could offer their method an advantage in the long run, helping to develop therapies that stick around, particularly for difficult to treat solid tumours.

Jae Choi

None of these preclinical models predicts exactly what happens in patients. But I think that we're potentially opening up new paradigms to think about how do we control functions biochemically and genetically with our data. I think we're potentially within a couple of years of really testing this to see whether it can actually go through. And in addition, we're within a couple of years of really finding out whether this is enough or whether we need to add and layer on more things with it. Using superpower analogy. I think you want someone that can be Clark Kent when the tumour is not there and become Superman in the tumour microenvironment and be able to transition back and forth and so we're really thinking very carefully about how to make this happen in patients.

Benjamin Thompson

That was Jae Choi from Northwestern University in the US. You also heard from Lionel Apetoh from Indiana University, also in the US. To read Jae’s paper head over to the show notes for a link.

Nick Petrić Howe

Coming up, the myriad ways researchers are trying to make batteries better. Right now, though, it’s time for the Research Highlights, with Dan Fox.

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Dan Fox

How would a lawn sprinkler spin if it sucked in water instead of spraying it out? Well, this question, that you probably never thought to ask, may have an answer thanks to a new experiment. In normal operation, an S-shaped lawn sprinkler rotates because the water shooting from his nozzles in one direction pushes the device to spin in the opposite direction. But if the sprinkler is underwater and sucking in water, the nozzles do not simply act as ‘reverse jets’, because the water flows in from all possible directions. These complexities have puzzled scientists since the problem was first laid out over 100 years ago, even proving a challenge for a young Richard Fineman who tackled the idea as a graduate student. Now though, researchers have carefully designed a new experiment, using an ultra-low friction bearing to remove confounding effects like turbulence. They found that the reverse sprinkler rotates forwards instead of backwards, but unsteadily, and at only about one-fortieth of its normal speed. Detailed observations backed up by mathematical modelling suggest that a weak jet effect inside the device dominates the sprinkler’s motion. Jet over to Physical Review Letters to read that paper in full.

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Climate change is erasing the environmental history preserved in a Swiss mountain glacier. Ice sheets and glaciers are natural environmental archives: they record the pollutants that are captured each year in snow, which is eventually compressed into layers of glacier ice. But with a warming world, researchers wanted to assess how these ice records are being affected. In 2018 and 2020, they drilled cores from the Corbassière Glacier in the Swiss Alps, at an altitude of around 4,100 metres. They found that the 2018 core contained ammonium, nitrate and sulphate ions – signatures of pollution lacing the snow had fallen year after year. But the 2020 core had much less of those signals in his deepest layers. That's presumably because warm air temperatures had melted the top of the glacier, and the meltwater had percolated deep into the glacier and literally washed away the ions. The authors say that in just two years, the glacier has been lost as an archive for reconstructing major atmospheric aerosol components. Read that research in full in Nature Geoscience.

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Nick Petrić Howe

A revolution in battery technology is necessary as we move into a more electrified future. Switching more technology to run just from electricity is a key step needed to achieve our goals on climate change, especially as more of that electricity comes from renewable energy. But that requires better batteries.

Currently, cars are leading the way, with many nations declaring that all new cars must be electric by 2035 or earlier. Putting a lot of pressure on researchers to come up with improved battery technology. Lithium-ion batteries have been crucial to this so far and they have come on leaps and bounds since their invention. But when it comes to cars there are speed bumps. Compared to petrol or diesel driven vehicles, electric cars are still limited in how far, or how little, you can drive them before they run out of battery. Charging times are longer than people may like. And, as anyone who has a phone knows, the lifespan of batteries can be an issue too. Tweaking such things can affect safety or increase weight. So how will researchers navigate these challenges to keep this revolution on the road?

Well, reporter Nicola Jones has been writing a Feature article about what the future of batteries may hold in Nature this week, so she’s joining me now to tell me what the batteries of tomorrow may look like. Nicola, hi! How’s it going?

Nicola Jones

Great. How are you?

Nick Petrić Howe

I'm good, thank you. So, as I said, I wanted to talk to you a little bit today about electric car batteries. And it seems like there's a lot of different things that researchers are working on.

Nicola Jones

Absolutely. Battery development is a huge field and there's a lot of interest in it right now with everything going electric in order to hit Net Zero targets against climate change. So the field is definitely very hot. And in terms of cars, the main message is we're going to see more diversity in car batteries in say, the next five years. So up till now, really, they've all been kind of lithium-ion, but that's going to change.

Nick Petrić Howe

But the thing about lithium-ion is there's a reason that that has been the technology of choice for electric cars. It’s a really– it's a very good technology for storing and using electricity, right?

Nicola Jones

Absolutely. It's a Nobel Prize winning technology. It really revolutionised a lot of things: laptops, cell phones, blah, blah, blah. And most batteries, people are trying to optimise six things all at once they want it to have enough power, like enough oomph to get going – that's the acceleration in your car. They want it to have a lot of energy density, which means you're packing a lot of energy into a little weight, which is really important for mobile devices like cars and cell phones. They want them to be safe, they can't burst into flame. They want to operate at temperature extremes, especially for your car, especially in Canada. And you need them to last over a good lifespan. So for typically for an electric car, that means about 1000 full charging cycles, which should take you about ten years, maybe twenty years.

Nick Petrić Howe

And it's not as if lithium-ion is a static technology. Researchers are also trying to improve this particular kind of battery as well.

Nicola Jones

Absolutely, there's been a lot of changes with lithium-ion since they were invented. And so battery chemistry is really complicated. And you can make big changes to the materials that are at one end of the battery or the other or the stuff that's in the middle of electrolyte. Or you can make teeny tiny changes to just the amount of dopamine or additives that are put into these materials. Tiny little membranes, alterations in the manufacturing process and all of these things can make a big difference or little difference. So people have been changing these batteries in increments and still are.

Nick Petrić Howe

So there are a lot of ways in which lithium-ion batteries themselves are being tweaked and improved. But as I understand one of the issues thus far when you improve the electrodes is that it can affect the safety and the lifetime of the batteries. So that's something researchers need to address. And one of the ways in which researchers are trying to address some of these issues is by using solid-state batteries, can you explain a little bit about what these are and how they may help batteries become better in the future?

Nicola Jones

Mainly what's happening is people are trying to change the positive-end and the negative-end of the battery into different materials that offer a greater energy density, theoretically. But one of the problems that happens when you use these better materials is in the liquid part between those two ends of the batteries, you end up getting these things called dendrites forming, which are basically little tendrils of lithium that extend across through the electrolyte and if they make it all the way across, they short your battery. So dendrite formation is a huge problem and people do not want this to happen in your batteries. You can't have a commercial battery where this is a common thing that happens. So one way of stopping that from happening is to take the liquid out and replace it with a solid. So something like a ceramic or a solid polymer. It really can help, it doesn't prevent it entirely, but it can help stop these dendrites from forming. And then you're like okay, now I can use the better anode, I can use the better cathode, I can reach those higher energy densities. Plus there are a whole bunch of other advantages, it's a sort of simpler design in some ways. But there are problems too, electrons or ions tend to move more slowly through a solid than through a liquid as you might expect. And so that can have a problem with things like charging times or power. So there are pros and cons.

Nick Petrić Howe

But yeah, I guess the challenge with solid-state is that we don't really know how to make it yet.

Nicola Jones

I mean, we can, there are companies out there that are making solid-state batteries – but it's tricky. The manufacturing process is tricky. You need the layers to be really well bound to each other and that's a hard thing to do. And they're just a variety of issues with the manufacturing, and even with the specific design that you're working on. And then it's hard to know exactly how these batteries are going to pan out. People do tests, obviously. But you still want to see them operating in the real world for a period of years before you really know how they're working.

Nick Petrić Howe

And another thing you wrote about in your article was this idea of a lithium air battery, can you explain a little bit more about what a lithium-air battery is and how that might work.

Nicola Jones

So lithium-air batteries are like a Holy Grail of battery research, you know, if you can get these to work, then wow, you'll get access to great energy densities theoretically. But it's really hard to do. But there was a group at Argonne labs that had a great lab results last year with a lithium-air battery. And so the idea here is that you have a lithium plate at one side, you have a solid-state material in the middle, and you're going to make a lithium oxide of some kind, at the cathode at the positive side. And because you're using the oxygen from the air, you don't have to carry that ingredient around with you. And they got great energy densities in the lab for this product. And they think they can have access to really huge energy densities, like almost as high as gasoline in gasoline powered cars. So we'll see where that goes and how that pans out. But for now, they have a tiny little lab test cell. And there's a lot of hurdles and difficulties in scaling these things up in manufacturing them, all sorts of issues to do with price and safety and longevity.

Nick Petrić Howe

And moving away from cars slightly as well. This incredible energy density that this technology could offer may be useful for things like aircraft, right?

Nicola Jones

Yes! Yes, that's right. Lithium-air has such a huge energy density that maybe it would be great for, yeah, battery powered planes, or helicopters or other craft. So right now, there's a lot of enthusiasm for air taxis. So maybe you get to the airport and you need to get to your hotel, you want to skip the traffic, you can get in basically, it looks like a little helicopter of some kind, it takes off and takes you to your hotel. And if you can have those, well, they are battery powered. But if you want them to be able to go further and carry more weight and not have to recharge so often than having a lithium-air battery would be great.

Nick Petrić Howe

I can't wait to see the regulations that those sort of things will need as they come into play.

Nicola Jones

Absolutely.

Nick Petrić Howe

And another thing that you talked about a bit in your article as well, is this sort of desire for cheaper batteries, batteries that are going to be more and more cost effective. What's the research sort of finding here? What are the ways that researchers are trying to make battery technology cheaper?

Nicola Jones

This is about the resources; this is about the materials that you're using to make your battery. And again, if you're thinking about all cars being electric, everything being electric, we're going to need so many batteries. And that just means so many million tonnes of material. And if we need to do that, we better pick the right ingredients, right, we want to pick ingredients that are not causing environmental havoc, in how we mine them or are really expensive or very limited in their supply. So a lot of researchers are trying to weed out certain elements from their batteries: cadmium, nickel, even the lithium itself. And this is where sodium batteries are a big thing. And sodium is a slightly heavier element, which you would think would be a bad thing because it means, well, we're trying to get as much energy in per weight and I’m swapping in for a heavier element. Why would I do that? But sodium is way more plentiful than lithium, like a thousand times more plentiful. Sodium is in the ocean, its everywhere. So if you can trade your lithium for sodium, then maybe you get like a cheaper battery. And maybe you can't get as much energy in for the weight, but that price difference could mean hey, this is a great idea for budget cars or lower end cars.

Nick Petrić Howe

I mean, it certainly sounds like researchers are pursuing a lot of different avenues to try and improve battery technology. What do you think the future holds?

Nicola Jones

Yeah, there are a lot of angles and I will not predict what's going to happen ten years from now but I will say that about five years from now you're gonna see still a lot of lithium-ion batteries in cars, but maybe you're also gonna see, you are going to see, sodium-ion batteries in a cheaper end of vehicles, those are already coming out in China. And you're going to see solid-state batteries in some cars so they're kind of slightly higher-end of the mid-range. And maybe in the far flung future, you're gonna see lithium sulphur or lithium-air for the really expensive ends of vehicles initially, that can go really far on a single charge.

Nick Petrić Howe

Well, I'll be interested to see how the future of battery technology shapes up. Listeners, if you want to read more about this, I'll link to Nicola’s feature in the show notes. But for now, Nicola, thanks so much for talking to me.

Nicola Jones

You too, thanks Nick.

Benjamin Thompson

Finally on the show, it’s time for the Briefing Chat, where we discuss a couple of articles that have been highlighted in the Nature Briefing. Nick, why don’t you go first this week, what have you got?

Nick Petrić Howe

Well, I’ve been reading an article in Nature, which is about an AI that's kind of learned things from a baby's perspective.

Benjamin Thompson

So many questions off the bat. Okay, when you say perspective, do you mean like, literally, or kind of emotionally? What are we talking about?

Nick Petrić Howe

I mean, literally, so in this study — which was reported in Science — researchers strapped a camera to a baby's head. A baby called Sam, I'll say, and basically, for an hour a couple of times a week, the baby would just live its baby life. And then that footage would get fed into a neural network, which then learns how to recognise certain objects from these experiences.

Benjamin Thompson

Right. So as a parent, then you're often talking to your baby, and you will say, cot or chair or mom, dad, whatever it is, right. And so that sort of thing was it looking where the kid was looking then? What’s the set up?

Nick Petrić Howe

That's basically it. So the AI itself was fed stills from the footage, so like photos of what the baby had seen. And then it had a transcript of the things that were being said around it. So parents, for instance, might be saying, like chair, or cot, or ball or that sort of thing. And then through those associations, the AI was able to then later recognise stuff. And it seemed to do pretty well at that; around 62% of the time it was right, which is similar to an AI that was trained on, like 400 million images. But obviously, this is a bit more of a constrained dataset, because it's just seeing what the baby's seen.

Benjamin Thompson

So it literally almost started as a blank slate then and it's kind of figuring out what things are based on just association.

Nick Petrić Howe

Yeah, exactly. And researchers hoped that this could be a way that we can better understand how you and I and babies acquire language. Because, you know, there's a lot of different theories going on there, it's quite a hard thing to understand, because babies aren't very good at talking, which is part of the problem. And so this could be a way to understand it. So there's a few different theories. So this, for instance, challenges some scientists who claim that language is too complex for it to happen through a general process, such as just drawing associations between things, which goes against the idea that there are some sort of special mechanisms that humans have in order to learn language. But of course, there are some sort of caveats to this, like this was data from one child who was wearing a camera every now and again. And it did struggle with some things. So it did best with words that look very similar most of the time, whereas other words, like for instance, toy, toy can be lots of different things. And it struggled to identify things that were toys, because it's quite inconsistent what a toy is.

Benjamin Thompson

Yeah, okay. So like a cot looks like a cot then right? You can't really sort of be any ambiguity as to what that is. Where does it go next you think? Because obviously, Sam was very small, is very small, is the plan to go further and look at kids who are slightly older, something like that?

Nick Petrić Howe

Well, one of the things that researchers want to do is try and tweak the model. So it can represent a baby's experience a bit better, because one of the things that babies are quite good at doing is learning words through their experiences. So babies, for instance, learn the word hand quite quickly. But babies have hands, they're able to interact with the world with hands, and the model does not. So, there could be ways in the future to sort of enable the model to, I guess, think a bit more like a baby. So that its able to acquire language in a more similar way to humans. So, we can better test some of these theories on how humans acquire language.

Benjamin Thompson

And so what you're saying then this isn't necessarily a way to sort of trying to super intelligent AI. It's, it's almost flipping it on its head, in a way to learn more about how humans actually learn about the world around them.

Nick Petrić Howe

Yeah exactly. And in the article, a lot of researchers were very excited about this, because it's a very interesting way to try and tackle how we learn languages as humans.

Benjamin Thompson

What an absolutely fascinating one, Nick, and how we learn about the world around us. And I've got a story that is involved in learning how the world around us works, but it couldn't be more different. Okay, now it’s a story in Nature, about how the return of a predator has affected more than just the food web. It's actually had a positive impact on coastal erosion.

Nick Petrić Howe

Oh, wow. Okay, so I've heard of stories like this before, like reintroducing wolves means deer get eaten, and that changes like the paths of rivers and that sort of thing. So, is this a similar sort of thing going on? Is a predator eating something, and that's changing the way an ecosystem functions?

Benjamin Thompson

Yeah, pretty much actually. So, this is a story that I read about in Nature and is based on a Nature paper. And listeners might remember a few weeks ago, I talked with the researcher about what happens when predators suddenly leave an ecosystem and there's a sudden crash, and what happens there. This is kind of on a theme, but this bit later on its like what happens when the predators come back? And in this specific example, we're talking about sea otters. Now I absolutely love sea otters because they're just so charismatic, right? I think my favourite fact is that they've got the densest fur of all mammals which keeps warm and dry, they got like kind of two different sorts of fur. But sadly, that incredible fur meant that they were almost hunted to extinction by humans. Well done us once– once again, right. And they used to be, you know, all up and down the west coast of North America, around to Russia and Japan as well. But sort of very lowest ebb, there's only maybe 2000 or so of these individuals left, right. So not a lot of otter to be very, very flippant. But things have changed since then. Okay, so hunting bans and conservation efforts have come in to help, you know, return these animals to their original populations, or get towards their original population size and go back to their old habitats. And one of these places includes the coastal salt marshes of California's Elkhorn Slough. So this is a giant ecosystem. And as you and I have heard on the podcast before, salt marshes, I mean, they’re absolutely crucial, right for a variety of different wildlife, but they're threatened by, you know, all sorts of different things.

Nick Petrić Howe

So this is about a predator that used to be in a place coming back to that place. So what were the sort of effects of that?

Benjamin Thompson

Well, this is where things take kind of a bit of a turn, right? So the otters themselves didn't have a direct impact on the coastal erosion. Right, what they did was, otters love to eat striped shore crabs, okay, they absolutely love eating these crabs, like these are burrowing crabs, otters will go down there, they are just munching them down, okay. But these crabs are interesting, because what they do is they will eat the roots of a plant called a pickle weed. Okay. Now, this pickle weed, it helps kind of bind the sandy banks together, right to protect them from erosion. And of course, these sort of environments are real peril through things like rising sea water, and you know, enhanced wastewater being flooded out. That– that sort of thing. And so the pickle weed was kind of holding things down to an extent. But of course, the crab was just eating them all and just doing so with abandon. Enter the sea otters which have come back, and the tables have turned somewhat. And the researchers wants to know, like, what sort of a difference were these mammals making. Okay, and to look for any correlation between the two, they looked at things like historical erosion rates, trends in otter population, and they did some experiments where they actually stopped any otters eating the crabs, right, called predator exclusion experiments. Okay, and looks– looks at what happened there. And the results were kind of stark, right, like so generally speaking, this area has seen erosion, like thirty centimetres a year, okay. And in areas of large otter population, this has been reduced to ten centimetres a year. All because of this kind of effects on the food where there's kind of top-down effects that these– these predators were having.

Nick Petrić Howe

I mean, that's quite a sizable impact. Does this result then mean that there's going to be sort of effort to help reintroduce otters into the area to help stop this erosion? Or does more data need to be gathered yet?

Benjamin Thompson

Well, as conservation efforts continue and as population levels continue to rise, there's a good chance that more stuff like this will be seen. And I think what's interesting is one animal can make such a difference, like such a small cog can make such a big difference in the environment. And if you think about, you know, the amount of money it would cost, you know, for human-built flood defences or things like that, that would cost an absolute fortune right. And, and I think, on a cost benefit scale, you know, otter conservation is relatively cheap, I think it's fair to say. But on that point, the losses haven't been reversed and there is still was erosion, right. So I think there are bigger issues at play, things like rising sea levels and what have you. And these are things that obviously require global efforts. But it does show that– that the otters are doing the business right. And I think it's not the only example of this right, I think like kelp forests, I read in the past that, you know, otters will eat sea urchins and keep the populations of those down because the urchins will decimate the sea kelp. So I think they remain charismatic, they remain one of my favourite sort of mammals, the sea otter and– and good luck to them, I say.

Nick Petrić Howe

I mean, good luck to them indeed. They seem to be doing some amount of good in certain environments. So that's great to hear. I think that’s all we’ve got time for this week on the Briefing Chat, but listeners for more on those stories you can find some links in the show notes where you’ll also find a link of where you can sign up to the Nature Briefing to get more like them direct to your inbox.

Benjamin Thompson

Let’s call it that for this week’s show then. We’ll be back next week with more stories from the world of science. In the meantime, you can keep in contact with us on X, we’re @NaturePodcast. Or on email we’re podcast@nature.com. I’m Benjamin Thompson.

Nick Petrić Howe

And I’m Nick Petrić Howe. Thanks for listening.