Briefing Chat: The tongue trick that helps sunbirds suck

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0:50Hi, listeners. Benjamin here. It's a holiday week for a lot of folk in the U.K., but that won't stop the Nature podcast. Now, the Artemis II mission is still going on. The crew are on their way back from the moon as we're recording this. We're hoping to have a special report on the mission later in the week. But for this episode, I've assembled an all-star team to talk about a few stories we've read about in the Nature Briefing. One of them is Lizzie Gibney. Lizzie, thank you for being here today. Hello, Ben. Good to be here. Thank you very much. And the other is Nature Briefing's Flora Graham.

1:22Flora, how are you doing today? Really, really well. Thank you so much. Good stuff. Well, listen, three stories today. Why don't I go first? And I've got a story that I read about in Nature, and it's based on a paper in Science Advances. advances. Now it has kind of a snigger factor to begin with but actually it could be a life-saving treatment and it's about eye drops made from pig semen. Wow, didn't see that coming. Right, so let's back it up. This story focuses on a cancer of the retina called retinoblastoma. Now thankfully this is a rare type of cancer but typically it affects young children, those under five.

1:57Now it can be successfully treated if it's caught early enough. But the treatment, as you might imagine, involves injecting drugs into the eye and chemo, laser therapy, these sorts of things. And this can result in loss or damage to eyesight. And of course, the side effects that come with chemo as well. And so a team were looking for another way to penetrate the barrier around the retina and deliver drugs directly into the eyes. And this is where the pig semen comes in. So why do they think to use pig semen? What's that got to do with it? Do you know what? That is a fair question, Lizzie, and it is a bit of a leap between the two, but there is a link.

2:33Now, key to this are particles, essentially little bubbles they are. They're called exosomes. Now, these are released by almost all cells in the body, but the exosomes in semen, well, they contain a lot of molecules that sperm need to do their job. Now, this includes the ability to open and close what are called tight junctions. Now, these are gaps between cells where they're kind of stuck together. And they need to do this on the way to fertilize an egg. And the researchers thought, well, hang on a minute. Maybe we can use this ability to get between cells to deliver something into the eye. And that's what they've done in this case.

3:11So is this something that's unique to pig semen or is this just like a mammal semen thing? Well, it's not unique to pigs, but pigs are used a lot in the biochemical research industry. So that's why the researchers went with them. And what they did was they took these exosomes and in studies with human corneal cells, now this is the clear dome at the front of the eye, of course, they found that pig semen exosomes could open and close these tight junctions, could essentially unzip the gaps between the cell, sneak in and then zip up behind them. And they could do this in, say, the external membrane of cells that covers the surface of the eye.

3:48Now, those were human cells in a dish, but they moved on, I guess, to show that this actually could be useful. And they loaded up these exosomes with a cocktail of cancer-killing things. And they tested these by using them as eye drops in mice. Now, we need to double-underline mice as always. And these were mice with retinal tumours. And 30 days after being treated, these tumours remained really small in the mice and they still had healthy eyesight. So as good as control mice who didn't have eye cancer. So what exactly do they think is going on then? These exomes are kind of allowing the treatment to get in?

4:25Yeah, essentially it can sneak in and I think it can get in via different parts of the eye as well. And of course, mice are mice, as we know, but the researchers, they did take things a little bit further. They did test them in rabbits as well, just to look for sort of safety and what have you. And they showed that these drops, these exosome-based drops, did seem safe after repeated application for 30 days, although there was some corneal irritation seen. So not there yet, but I think this is a step in the right direction. But from what I understand, some irritation would still be vastly better with some of the other methods that they're using to get those drugs into people's eyes at the moment.

5:03Oh, absolutely right. But this is a proof of concept. There are questions that remain. Will it work in humans at all? Would there be any negative effects for long term application? These things are yet to be figured out. But I think some folk quoted have said that this is potentially quite an exciting development. I'm sure there's lots of gross bits of nature that have ended up in our medicine. And this could maybe be another one of them soon. And also there are lots of barriers in the body that the human body uses to keep stuff either in or out. You think about the blood brain barrier. That's the kind of the classic one, right?

5:33The body is very good at keeping stuff out of the brain. So maybe this kind of exosome based therapy could be used to sneak things in to the brain as a treatment for a variety of different diseases. Well, it could well be something we'll have to follow to see. where it goes. But let's move on to another story today. Lizzie, why don't you go next? What have you got this week? So this is a story also in nature and it's unsurprising and depressing, but well done and important. Hopefully that's tantalised you. It's a story about the motherhood penalty of being in academia. So I'm sure a lot of our listeners are probably well aware of this.

6:13Many have experienced it, but this is a study that has really quantified it and sought to try and explain it. So these are some researchers at the London School of Economics. And they did studies using some big databases and data coming out of Denmark, which is actually a country that's kind of known for being pretty equal as things go. You know, they subsidise child care over there, they've got good parental leave. But this study looked at 13 ,000 parents who had enrolled in a PhD and then later went on to have children, looked at things like their publication records, and also surveyed a big chunk of them as well.

6:44And they found out that eight years after having the first child, women were 29 % less likely to be employed at university than if they had not become a mother. There was also a penalty for men, but that was about 14%. And there was a similar pattern for having, in fact, any career in research. So it showed that a lot of women just leave research after they have kids. They also, as I say, did some really thorough work looking at lots of different data that were available. And they also found that women were 35 % less likely to get tenure than if they hadn't become parents and that didn't apply for men and overall made 31 % fewer publications than men did.

7:24It's very stark. There's some really good charts that you can look at in this story that just show kind of that men and women are kind of tracking before they have kids and then they have their kids and then they just absolutely their paths separate. And did the researchers look into what exactly some of the factors are that create this motherhood penalty? Yeah, it's hard to exactly pinpoint one to one, but the survey that they did, I think, was really enlightening. They showed that even in, as I say, this country, which is renowned for being fairly egalitarian, women were taking on much more of the nighttime care for the kids.

7:56And when kids were sick, women were much more likely to be responsible for looking after them. Doctor visits, nursery pickup, these were all things where in this survey, women said they did the vast majority of that compared to their partners. So of course, even when both parents are working, both parents perhaps have, you know, really pursuing their careers, it's often the case that the mothers end up being the ones who actually day to day are taking the hit. And of course, in a field like this, where your publication rate, your citation rate, it can be really cutthroat what you're judged on.

8:30Unfortunately, that is having ramifications. So Denmark's done a lot of work to try to equalise some of the burdens of parenthood. Did they reflect at all on whether those approaches showed that they were working or not necessarily? The main issue seems to be that they talk about time, that there have been measures, but a lot of these things take a long time to come through. And I think some positives to take out of the story are that, for instance, in labs where there were more women in senior positions, this penalty was less pronounced, which I thought was also very interesting. So one takeaway was, yeah, getting more women into senior positions in the first place can then have a kind of trickle down effect with supporting the more junior women as well.

9:13And there are folk listening to this who will be saying, tragically, this remains not a surprise. Obviously, this was a study in Denmark. One can imagine this is true across the board, of course. What are folk saying about it and what can be done more broadly, do we think? The big thing here is that we have this data, like if you're going to try and make changes, data is always the place you need to start. You need to show what measures are working, you know, which aren't and the size and scale of the problem and where it's coming from. So I think the biggest response to this paper was just, you know, people were happy that it was being really thoroughly documented.

9:44And the data are very, very rich and really, really striking in their findings. I mean, the fact is we're always arguing against this attitude that it's the competence of the women that's to blame. So that data is so key for just heading off that misconception right away. It might be reassuring as well. I've got friends in academia who are mothers trying to navigate this themselves and maybe just saying, okay, actually, it's not me. I've not lost the plot. Actually, this is really difficult. This is a challenge that a lot of people are facing, and there's some fundamental kind of systemic reasons why.

10:15So this story really struck me because we recently covered a similar paper talking again about the motherhood penalty, again, based on data from Denmark specifically. This one was in European Sociological Review, what it found was it could put a value, a rough value on the financial hit that mothers take in the first two years after becoming a mother. And they pegged that at about 120 ,000 US dollars. But what they did find was the generous parental leave policies, paternity leave policies that they have in Denmark actually offset the financial hit of that by 80%. So that's interesting for policymakers who are looking to this range of research to inform, you know, what can actually be done about all this.

11:00It does seem that, you know, although it's certainly unfortunate that there is still a big motherhood penalty in Denmark, the investment that's been made into making things better is paying dividends. Yeah, that's so interesting. So I wonder if this study was done somewhere else, if the penalty would be even more severe. Well, I think we've got time for one more story this week. Flora, why don't you bring it home? What have you got for us? So this is a study from Current Biology, and science covered this story. And the exciting headline here is that scientists have discovered a whole new way to suck.

11:31This is about how sunbirds get nectar out of flowers. Now, sunbirds are quite similar in appearance to hummingbirds, which are another nectar-loving bird. But scientists found when they looked closer, However, sunbirds are using a totally new and unique way to get nectar out. So hummingbirds stick their tongue out of their long beaks over and over and over into the flower, whereas sunbirds form their tongue into a V shape, creating suction against their beak. And this is the first time that a vertebrate has been observed, creating suction using only the tongue, not reshaping the mouth or the lips, since obviously some birds have a beak.

12:17So in order to discover this finding, I was quite charmed that the scientists created a transparent artificial flower so they could really see what was going on here. Right, I've seen a video of this and it's quite something, right? Because it began with, these two animals look kind of the same. Surely they must eat in the same way. And I've seen a lot of the anatomy now of hummingbird beaks and sunbird beaks from museum specimens and watched a lot of fluid dynamic videos as a result of this. And I think it's safe to say that sunbirds, they really do suck. But we mean that in the nicest possible way.

12:48So the hummingbirds, I'm imagining it's like lapping like a cat. I'm thinking anteater. You know, you've got this long kind of conical beak and you've got the tongue that repeatedly goes out and in. One of the researchers quoted in the science article said it was brought into the mouth and ringed out like a wet towel. So yes, that's apparently how the hummingbirds are doing it. But then the sunbird does something else. And it's not like we would just, you know, like sucking up with a straw, because obviously we have a mouth and cheeks that can move and you can kind of create that sucking. Exactly.

13:17So if you're one of those people lucky enough to have the genetic quirk that makes you able to roll your tongue, you know that you can put your tongue into a shape, but you'd be hard pressed to only press that up and down against your hard palate in order to drink a glass of water. However, these sunbirds have mastered using the shape of their tongue, manipulating the shape of their tongue to cause the nectar to go into their mouth. And unusually, sunbirds have a partially transparent tongue. I learned learning about this as well, which is how the researchers could visualize this nectar going up.

13:49So yeah, by pushing their tongue up against the roof of their beak, it creates this kind of pressure difference and sucks up the nectar. It's quite something. And one of those, we have no idea how this works, but now we do stories, right? Absolutely. And this is exactly the kind of thing that engineers can use, possibly in some future application. So knowing how biological systems work isn't just fascinating. It's also really handy for coming up with biomimicry in the engineering world. Well, that story was a sweet tonic for us all. I think we can agree. But I think it's time to leave it there for this week's show.

14:22We'll put links to all of those stories in the podcast notes and a link where you can sign up for the Nature Briefing to have Flora send you even more stories like this directly to your inbox. But for the time being, all that's left to say is Lizzie and Flora thank you both so much for joining me today Thank you Ben, bye