JWST shows an ancient galaxy in stunning spectroscopic detail

Benjamin Thompson

Welcome back to the Nature Podcast. This week, taking a fresh look at an ancient galaxy with JWST...

Nick Petrić Howe

...and how coral reef fish became so productive. I'm Nick Petrić Howe...

Benjamin Thompson

...and I'm Benjamin Thompson.

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Benjamin Thompson

Some one million miles away from Earth floats, the James Webb Space Telescope, also known as JWST. After decades of preparation, it finally went into operation last year, and its mission is to collect data on the cosmos with its images wowing the world and giving science nerds new desktop backgrounds for their computers. One of the things JWST has been doing is peering far out into the distant universe and, because light takes a long time to reach us, the distant past, to look at galaxies that are thought to have formed, not that long after the Big Bang. By learning more about these galaxies and how they came into being, researchers hoped to piece together how the universe evolved into its current state. One of the most distant known galaxies is JD1, which was actually discovered about a decade ago using JWST's predecessor, the Hubble Space Telescope. Now, in a paper in Nature, a team has trained the JWST sights on this galaxy and used its power to magnify our understanding of the distant body. To find out more, I spoke with one of the papers authors, Guido Roberts-Borsani, from the University of California, Los Angeles in the US, who started by telling me what was previously known about the galaxy JD1.

Guido Roberts-Borsani

Well very little really, the galaxy was identified with the Hubble Space Telescope back in 2014. And we really didn't know very much because there wasn't too much that Hubble could really do, we could maybe study its size a little bit, and we could estimate its distance. And we deal in distances in terms of what we call the redshift. The redshift is basically a factor that describes the expansion of the Universe. So a higher and higher redshift corresponds to earlier and times, we thought it was at about a redshift of 10, which corresponds to about 500 million years after the Big Bang. But that was a highly uncertain variable if you want. And so it's only really with James Webb now that we can start studying in detail that we really couldn't before then.

Benjamin Thompson

So what can the James Webb Space Telescope the JWST do then that previous telescopes in space and on Earth couldn't.

Guido Roberts-Borsani

So Hubble is primarily an optical and near-infrared imaging telescope. The majority of light from very distant galaxies is emitted in longer wavelengths of the infrared, the wavelengths that Hubble simply can't reach. James Webb is much more sensitive to those wavelengths. And so it can identify these distant galaxies much more easily. And finally, James Webb has what we call spectroscopic capabilities, it is able to split white light into its constituent energies. And you can see signatures of oxygen, of carbon, of hydrogen, all these sort of things, that allows us to pinpoint the distance to galaxies, pinpoint how many stars they're forming, what their mass is, gives us a wealth of information, which we just can't get from imaging. We can do this with ground-based telescopes, but it's much harder. So James Webb is really a game changer in that sense.

Benjamin Thompson

So the telescope then has been pointed out at this galaxy to learn a bit more about it. But it's actually a little more complicated than that. Which is not to say that that's an easy thing to do at all, of course, because this galaxy actually appears in triplicate, it can be seen three times in the sky, because it's actually behind some other galaxies. Maybe you could explain a bit about that.

Guido Roberts-Borsani

Yeah. So this is the effect of what we call gravitational lensing. If you have a cluster of very massive galaxies that are nearby to us, between us and that distant object, they act as nature's magnifying glass if you want. So for instance, if we have a very distant object that resides behind that cluster, the lights that would ordinarily miss us gets bent around and amplified, so the distant galaxy appears brighter than it ordinarily would. And those light rays get bent around to different parts on the plane of the sky. And that's why we can see the same galaxy at different points in the sky. It's just that its light has been warped around this cluster of galaxies.

Benjamin Thompson

And this lensing then amplifies the light and you combine that with the JWST to really get a sense of what's going on with JD1. What were you looking at specifically, when you were peering at this galaxy.

Guido Roberts-Borsani

This galaxy, actually, we probably wouldn't see if it wasn't gravitationally lensed. And since this was a fairly high profile galaxy that had been discovered with Hubble, one of the most distant ones, it was a logical target to see what kind of things James Webb could reveal to us. And so one of the first things we wanted to do, because without that piece of information we can't do anything is determine its distance. So we targeted the brightest components of these three images. And we took a spectrum, and we're able to pinpoint it residing only 500 million years after the Big Bang. So very, very far away at the distance we thought it was. And then we can see that it's forming stars pretty quickly. It has some elements such as oxygen, carbon, these sort of things that we infer from its total light. And because the resolution of James Webb is so much better than what we had previously, within this galaxy, we can start resolving individual clumps. So rather than seeing just one sort of blob on the sky, we now resolve that blob into individual components. And so that's a very nice thing that we hope to study in a bit more depth in the near future.

Benjamin Thompson

And it seems like this telescope is finding lots of distant galaxies and potentially seen some much older ones, how does your paper helping the understanding of these really old galaxies?

Guido Roberts-Borsani

So James Webb is finding a lot more very, very distant galaxies that are very, very bright, more than we initially expected, based on our observations with Hubble, but all of these galaxies remain candidates for now, we estimate their distances, but the signatures with which we try and estimate their distances can be mimicked if you want by galaxies that are close by actually. So we need the spectroscopy to be able to determine accurately what their distances are. And so our study of JD1 is a good example of trying to follow up galaxies, which we think are very distant and confirming their distances.

Benjamin Thompson

So you've used JWST then to really increase what's known about JD1. And this chimes of what was previously shown, what does learning more about these distant galaxies that came into being, not that long after the Big Bang in cosmic terms at least, tell us about the early Universe and how things evolved from then?

Guido Roberts-Borsani

It tells us how quickly galaxies might have formed and evolved in the very early Universe. It also tells us how rapidly perhaps the Universe evolved from one that was opaque to UV light. So just filled with hydrogen, the one that is fully transparent, and the beautiful one that we see today. And so studying these sources really tells us how these galaxies influenced their immediate surroundings to create the universe we see today.

Benjamin Thompson

And on a personal level, I mean, as someone who uses the data this new telescope produces in your work, what does it mean to you and maybe more broadly, to science in terms of learning about the Universe?

Guido Roberts-Borsani

It's incredible, as a junior researcher to now base a huge fraction of my career with this telescope, it's incredible. I've been studying distant galaxies for a little while now. But we were using telescopes on the ground to try and get the spectra confirming the distances to these, supposed distant galaxies, and we would spend entire nights trying to get the faintest signature possible to confirm these distances. And now you can do it in just an hour with James Webb. And you can get a wealth of information that we could only dream off. So it really is a game changer, just in terms of its spectroscopy. And so I'm very excited to be able to use it now for the next few decades to try and learn more about the early Universe. And ultimately, the study of distant galaxies really is sort of trying to understand our own origins, really, when did the first elements form in the Universe that ultimately gave rise to our Sun, our Solar System, the Earth, ourselves? So it is a study really, of our own origins.

Benjamin Thompson

I mean, I saw that you were actually at the launch of the telescope too.

Guido Roberts-Borsani

Yes.

Benjamin Thompson

So you've been on a bit of a journey, as it has as well.

Guido Roberts-Borsani

Yeah. You know, I had heard a lot from my mentors who were there when Hubble had launched and hearing what an experience that was. And, you know, I thought, Well, I would love to do that with James Webb and see the launch there, because my whole postdoc here at UCLA, is to analyze the first data with James Webb. And so I thought, well, I'd like to create my own story with this telescope. So I booked tickets to French Guiana, and I was lucky enough that I did see it and it was pretty incredible. You know, you only see the plume of the rocket for 10 to 30 seconds or so. But then you feel the rumble. You hear the rumble. And it's pretty incredible also seeing the reaction of all the people who work directly on the launch and the telescope and the palpable relief that you see from them when everything goes right.

Benjamin Thompson

That was Guido Roberts-Borsani. For more on the work, look out for a link to his paper in the show notes.

Nick Petrić Howe

Coming up delving deep into evolutionary history to find out why coral reef fishes grow so quickly. Right now though it's time for the Research Highlights with Dan Fox.

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Dan Fox

Are you plagued by mosquitoes? Well your choice of soap may be playing an important role. Researchers investigated whether female Aedes aegypti mosquitoes were attracted to nylon sleeves that had been worn by volunteers. Each volunteer had one unwashed arm and one arm washed with one of four brands of soap. The team found that for some participants, mosquitoes were more attracted to sleeves worn on arms washed with either Dove or Simple Truth soap brands than those worn on an unwashed arm. Meanwhile, sleeves worn on arms bathed with Native brand soap tended to repel mosquitoes. Analysis of the soaps revealed four compounds that attracted mosquitoes and three that seemed to ward off the insects. The researchers say the findings could help to develop chemical blends to either repel or lure the blood-sucking creatures. Sniff out that research in iScience.

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Dan Fox

Tiny tardigrades have inspired a design of swimming microrobot developed to deliver precision medicine. Magnetically powered swimming microrobots hold potential for delivering drugs to hard to reach body tissues. But such robots typically struggle to cope with the high rate of blood flow, limiting their ability to stick to their target sites in blood vessels. To address this, engineers have taken inspiration from tiny invertebrates called tardigrades whose claws allow them to grip plant matter in aquatic environments. This enables the creature to survive in fast-flowing liquid. Researchers attached similar claws to magnetic swimming microrobots and covered them with an outer layer mimicking a red blood cell membrane. They found that this improved the bots adherence to the inner wall of a rabbit vein. The clawed microrobots could stick to the vessel wall even at a flow rate comparable to that in a major vein, in contrast to control magnetic particles which rapidly detached. Read that research in full in Science Advances.

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Nick Petrić Howe

In shallow waters across the world, there are bounteous environments of colour and life. Coral reefs. These fragile ecosystems are amongst the most productive in the world, with a vast variety of fish and life that grow very quickly. And this is accomplished even though these environments have relatively low nitrogen and phosphate, key ingredients for life. This seemingly bizarre contradiction has long intrigued scientists who've been trying to work out why, how and when the fish that inhabit these ecosystems became so fast growing and productive. It has been thought that these fast growth-rates developed around the time that coral reefs themselves evolved. The thinking being that something about this environment allowed fish to grow more quickly. But a paper in Nature this week seems to show that that isn't the case. To find out more, I caught up with a couple of the paper’s authors, Helen Yan and Ali Siqueira. I started by asking them why they're interested in coral reef fish. Here's Helen first.

Helen Yan

I think coral reefs get a lot of attention, because they're beautiful to look at. It's warm, tropical water, but they actually present a pretty unique system where they're hyper-productive in what's considered low-nutrient environments. So they're kind of this scientific enigma, ans we're trying to figure out why that is.

Nick Petrić Howe

Can you sort of tell me like when you first starting out, what was your sort of plan? What was your sort of idea for this paper?

Helen Yan

I think Ali tells it best because there's a fun story around it with our boss.

Ali Siqueira

The idea for this paper actually came about mostly from throughout the last 30 years, he has been thinking about this question, Professor David Bellwood, because he thought that growth-rates increased in the Miocene, between 25 and 5 million years ago. So the idea came from 30 years of coral reef research looking into fish and trying to think, when did they start to grow fast? But funny enough, what we found was that it started to grow fast at a different time than he had originally thought. So it was kind of hard to convince him and at first.

Nick Petrić Howe

What did you do to try and work this out, then in this paper?

Ali Siqueira

I think there were two main steps that are important to talk about. The first one, we needed to have a framework to be able to predict growth across many species of coral reef fishes, because basically, we had growth data for many species, but not across all species. So that was the first step that we took. So we developed this modeling framework to be able to predict growth for species that we didn't have data for. And the second step was to be able to reconstruct the rate of growth of fishes across a large-scale phylogenetic tree just to try to detect the points in time in which we see any shifts in the evolution of growth rates.

Nick Petrić Howe

And did you find such a point in time?

Helen Yan

We did. And so we were expecting to find this about 20 million years ago, where there's a lot of diversification across coral reef fishes, we thought with more species meant this is when these faster growth-trajectories came up. But we actually found it between 50 and 60 million years ago. So way earlier than we anticipated.

Nick Petrić Howe

Do you have an idea of what happened 50 to 60 million years ago, what was going on that meant that suddenly a lot of fish are like 'Hey high need to grow a lot faster'?

Ali Siqueira

Yeah, we know from fossils, that that was a point in time, when many families of the fishes that we see today on coral reefs, they started to appear. But what we didn't know is that it seems like the origin of these fast growth-trajectories, also seems to be correlated with the origin of some of these groups that appeared 55 to 33 million years ago. But we kind of speculate in the paper, the fact that this point in time was very warm period, geologically speaking. And there's one thing we know from fish today is that warmer temperatures generally lead to faster growth.

Nick Petrić Howe

And so I would guess, as well, that because a lot of fish seem to have gone towards this faster growth-rate it which give them some sort of advantage. So what could it have given the fish to, you know, give them an advantage over slower-growing fish?

Ali Siqueira

One important thing to mention about fast against slow growth-rates, I guess, is that usually fast growth is also associated to reaching smaller body sizes in general. So in terms of the ecology, of coral reefs, you would think that because these fishes were actually growing faster, but to smaller sizes, they were more subjected to predation. However, there was another key evolutionary event that happened after the development of these faster growth-trajectories, which was the development of reefs the way we see them today, basically. So the development of corals came at a later stage around 20 million years ago to 5 million years ago. And the formation of these reefs, we think, was the main driver of the maintenance of these fast growing and small body size fish, because it provided exactly the refuge against predation.

Nick Petrić Howe

I suppose, though, what happened in the sort of 30 million years between where they didn't have that refuge?

Ali Siqueira

Very good question again, back then, throughout this time, they were definitely not as diversified as they were, once reef systems started to develop further,

Nick Petrić Howe

Right. So like the warmer temperatures in the Eocene made them tend towards faster growth-cycles. And then the coral reefs came about later. And this was the perfect habitat for them.

Ali Siqueira

Absolutely. Right.

Helen Yan

It's kind of like the warmer waters gave the fishes these tools to be able to grow fast, and then they could really exploit them down the road.

Nick Petrić Howe

Ah gotcha, gotcha. And so what do you think this can tell us about coral reef fishes today?

Helen Yan

It kind of explains why they're able to maintain such high levels of productivity. You have the fastest growing fishes in all the oceans found on these lower reef systems. Even though you know they exhibit similar body sizes to some of the colder water fish. They're just reaching those sizes super fast. And so with future ramifications, we don't really know how that might play out. But it kind of explains that one piece of that puzzle.

Nick Petrić Howe

Speaking of the sort of future ramifications today, coral reefs are going through a lot of changes, including warmer temperatures. Does this work tell us anything that can help us sort of, at least alleviate sort of what is happening to these delicate ecosystems?

Ali Siqueira

Well, in fact, quite the opposite. It doesn't really helped alleviate much because as I mentioned earlier, even though we're describing this shift towards faster growth, they're growing to smaller body sizes, after all. So this can have huge consequences for, for example, fisheries in the future. There have been some papers published on describing this idea that with warming waters. Fish might grow faster, however, reach smaller sizes. So for humans that depend on fish to live, this can be really problematic, unfortunately.

Nick Petrić Howe

And what do you think are the sort of implications of this paper?

Helen Yan

I think it's really cool that we can look into the past and kind of understand how the future might shape out to be. And although we're talking about completely different timescales, it's one of those things like these laws of physiology that before based on theories and equations kind of hold true, even when we're going back 150 million years. So even though there's a great deal of evidence coming forward, saying, you know, coral reefs are changing, the oceans are changing. But there's uncertainty, it kind of puts an asterix next to the uncertainty because I think we're getting a better idea of where it's headed.

Nick Petrić Howe

That was Helen Yan. You also heard from Ali Siqueira. And they're both from the James Cook University in Australia. To find out more about the evolution of these fast-growing fish, you can find the paper in the show notes.

Benjamin Thompson

Finally, on the show, it's time for the Briefing Chat, where we discuss a few articles that have been highlighted in the Nature Briefing. Nick, what have you got for us this week?

Nick Petrić Howe

Well, I've been reading a story in Scientific American about a frog that may be the first ever amphibian that's a pollinator.

Benjamin Thompson

Alright, so pollination, then a hugely important biological process. But usually, I think of it as being done by bees, I guess, and maybe butterflies. But insects, generally speaking.

Nick Petrić Howe

Yeah. And I think that's what's been thought for a long time, there have been plenty of animals and creatures that visited flowers, and there are different creatures that do pollinate things. So there are, for example, lizards in South Africa, that seem to pollinate flowers as well. But we've never so far seen an amphibian doing so. So this is a little tree frog in Brazil from just outside Rio de Janeiro. And it seems to be one of the first amphibians to eat fruit, and now also to pollinate flowers as well.

Benjamin Thompson

So this is the first one that's been described, as you say there. So I guess pretty rare, potentially. How do we know that it's doing what the scientists think it is doing?

Nick Petrić Howe

So we don't know exactly whether this is a pollinator, the researchers who observed it had suggested that it may be. But what happened was in 2020, the researchers observed this frog called Xenohyla truncata apology to any Latin experts out there. And they observed gathering around the milk fruit tree and going inside the flowers and feeding on the sweet nectar. And then when it emerged from the flower, it had stuck all over its back pollen. And so the researchers have suggested if it's doing that, and then you know, taking it to other flowers as it feeds on their nectar, it could well be pollinating. But there is some amount of debate, which we can go into.

Benjamin Thompson

I mean, I guess just seeing it move from flower to flower isn't directly evidence that that pollen is pollinating another plant.

Nick Petrić Howe

Exactly that, is unclear whether this pollen actually moves to another plant, and you know, pollinates it, allows it to reproduce better. And also the pollen is stuck onto the frogs back with some sort of sticky secretion. And we don't know whether that stops the pollen getting to other plants, or whether it actually damages the pollen in some way. So there were still questions to be had about whether this is actually a pollinator or not, because typically, what you want to know is that this animal doing this is going to benefit the plant in some way, it's going to reproduce better. And so researchers have suggested there's a couple of follow-up experiments they could do, they could put cages around the flowers to block the frogs going in. And then if that damages the flowers' reproduction, then that would suggest that the frog is indeed pollinating it. So there's still more to do. But it's really interesting, because no one's ever seen a species like this interacting with a flower. And this seems to be a bit of a trend of us seeing more and more different kinds of pollination that we've never seen before.

Benjamin Thompson

I mean, you mentioned there that researchers had seen a lizard pollinating a flower, which is something that I'd certainly never heard of. So it seems like that this process could be a lot more sort of diverse than previously expected.

Nick Petrić Howe

Yeah, exactly. It's quite hard actually, to see pollination occurring. And we can't really rely on people just seeing stuff happening and being like, oh, yeah, that's happening. But with the sort of technologies that we have now we have a lot more like long-term monitoring and camera technology, so we can actually witness these things happen. So those lizards that you mentioned, for example, they've only ever seen video footage of that. So there are potentially a lot more pollinator interactions going on the world over, but we just don't know.

Benjamin Thompson

And we've talked quite a lot about the plant here. But of course there is another member of this partnership and it is the frog. What do we know about this could potentially be getting some benefit from this as well?

Nick Petrić Howe

Well, it will certainly be getting some benefit from feeding from the plant, like nectar is quite sugary, it's quite calorie dense. So it will be getting some good food from it. But in terms of a greater benefit, it may be that now it's been seen to have this very unusual interaction, it could give us more of a push to actually protect the species. So it's actually a threatened species. And it's not really considered much in Brazil, according to the researchers interviewed in this article. And so by saying this is a pollinator, it could give more of an impetus to actually protect it.

Benjamin Thompson

Well, that is a very neat story. And I always like hearing about things that are new to science. I've got a story this week that I read about on the Associated Press website. And it also involves an animal that is under quite severe threats. But in this case, it's the koala an iconic marsupial found in Australia. And it's a story about a new vaccine to protect them from a serious bacterial infection.

Nick Petrić Howe

I guess this bacteria must be causing quite a lot of problems then for us to try and make a vaccine for it.

Benjamin Thompson

Well, absolutely. And koalas really aren't having the best of times at the moment. And last February, the Australian Federal Government declared these animals endangered in parts of the east of the country, and they're facing multiple threats: devastating wildfires, other the habitat loss, being hit by cars, all sorts of things. But also there's this disease called chlamydia, commonly a sexually transmitted infection, a bacterial infection, and it affects the koalas very, very badly, it can cause blindness, infertility, and even death. And one study in New South Wales suggested that maybe 10% of the koala population in the northern part of that area were infected in 2008. And that's up to maybe 80% now. So this disease is rampant, and it really is affecting the populations. But as I say, researchers are trying to turn the tide a little bit and they have begun vaccinating wild koalas in a field trial.

Nick Petrić Howe

So why are researchers trying to use a vaccine for this are there not other ways? So when I think of bacterial infections, I often think of antibiotics and stuff like that.

Benjamin Thompson

Yeah. And that's a good point. And antibiotics can be used to treat chlamydia infections in humans and in livestock, for example. And they can be used in koalas as well. But koalas don't really respond very well to this sort of treatment. And you have to give them a massive dose. And it's obviously hard to give those doses to wild animals. And so there's been this drive for quite a long time to develop a vaccine that could alleviate these issues.

Nick Petrić Howe

So they're doing a field trial then, but how does one go about vaccinating koalas they must be quite tricky to find?

Benjamin Thompson

Yeah, well, in total, they're looking to inoculate 50 healthy animals and monitor them. So that's about half the population in this place called the Northern Rivers region in New South Wales. And this vaccine was developed a couple of years ago, and it's a single shot vaccine designed specifically for koalas, and it was trialed in animals that were brought in to wildlife centers for treatment for other conditions. But what researchers really want to understand is the impact of vaccinating wild populations, can reduce infection and disease. And so that's what they're trying to do and first koalas were caught in March and this field trial is due to last perhaps three months. And in terms of catching a koala. I mean, there's a great quote in this article that said, "It's hard to confuse them with any other animal." Like it's obviously a koala. But what they do is they put an enclosure round the bottom of a eucalyptus tree because that's what koalas eat. And it says that after a few hours or days, these koalas climbed down looking for another tree and they pop into this enclosure, and they're then caught, and so they can receive this jab and they're checked over for about 24 hours. And then they're dyed with a little bit of pink dye. So the researchers don't catch the same ones repeatedly. And then they're released. And there's a neat little video in this article showing the first wild koala to be inoculated released back and koalas are surprisingly pacy. Once the lid is released off of this cage at the bottom of this tree, it shoots up this eucalyptus tree and off it goes on its merry koala way.

Nick Petrić Howe

That's really cool. And is it having any sort of effect on you know, protecting the koala populations?

Benjamin Thompson

Well, this is currently unknown. And this is what the researchers are really trying to figure out. And it's interesting because actually, there is a decision on whether or not it's right to vaccinate wild animals, right, there's a risk of disturbing them versus the risks of the disease. So this trial was approved by multiple government bodies, and we'll have to wait and see on the results and that maybe this might alleviate at least one of the pressures on this iconic species.

Nick Petrić Howe

Well, it'll be interesting to see how this goes over the next few years and whether it can be used to protect this species. So thanks for telling me about that, Ben, and listeners for more on the stories and for where you can sign up to the Nature Briefing to get more like them check out the show notes for some links.

Benjamin Thompson

And that's all we've got time for this week. But don't forget, you can always reach out to us on Twitter. We're @naturepodcast or you can send an email to podcast@nature.com. I'm Benjamin Thompson...

Nick Petrić Howe

...and I'm Nick Petrić Howe. Thanks for listening.