Science Friday - Redlining and Baltimore Trees, The Root Of A Gopher Mystery, Cold and the Nose, Glass Frogs. Jan 6, 2023, Part 2

Episode Date: January 6, 2023

How Redlining Shaped Baltimore’s Tree Canopy Redlining was pervasive in American cities from the 1930s through the late 1960s. Maps were drawn specifically to ensure that Black people were denied mortgages. These discriminatory practices created a lasting legacy of economic and racial inequality which persists today. Less obvious is how redlining has shaped nature and the urban ecosystem. A recent study found that previously redlined neighborhoods in Baltimore have fewer big old trees and lower tree diversity than other parts of the city. These findings are part of the Baltimore Ecosystem Study, a collaborative research project which has tracked the city’s changing urban environment for the past 25 years. But it’s not all bad news. The city has a comprehensive tree replanting initiative and is now working to restore its tree canopy. In 2007, Baltimore set a goal to increase the tree cover from 20% to 40% by 2037. Since then, officials have been working closely with non-profit community organizations to plant trees all over the city—especially in previously redlined and otherwise under-served neighborhoods. Ira talks with Karin Burghardt, assistant professor of entomology at the University of Maryland about her latest research into the effect of redlining on Baltimore’s tree ecosystem. And later, Ira speaks with Ryan Alston, communications and outreach manager for Baltimore Tree Trust, which has planted over 16,000 trees in the city to date.   What’s Going On Underground With Gophers? Pocket gophers, also known as gophers, are often viewed as a pest species. But their extensive tunnel networks are good for soil and help shape healthy ecosystems everywhere gophers are found. Producer Christie Taylor talks to two University of Florida researchers who investigated the mystery of the pocket gopher—why does a single gopher build such a large network of tunnels? What they found led to deeper questions about how gophers get enough food for their extensive energy needs, and whether they might even be cultivating roots in a deliberate act of farming. Plus, why pocket gophers deserve our appreciation as ecosystem engineers.   How This Chemist Is Turning Agricultural Waste Into Water Filters Activated carbon filters have become common household items as water filters in pitchers, or directly on your faucet. These activated carbon filters are also used in industrial processes like wastewater treatment and to filter out chemicals released in smokestacks. Dr. Kandis Leslie Abdul-Aziz, assistant professor of chemical and environmental engineering at University of California Riverside, has created activated carbon filters from agricultural waste like corn stover and orange peels. Abdul-Aziz talks with Ira about her research, and what it will take to shift manufacturing processes to be more sustainable and less harmful to the planet.     The Nose Knows When It’s Cold—And It May Get You Sick It’s something most of us know from experience: When it’s cold outside, you’re likely to see a lot of people sneezing and coughing. Upper respiratory infections, like the flu, colds or even COVID-19 are common in winter. But understanding the biological reasons why hasn’t been known—until now. Researchers at Mass Eye and Ear cracked the mystery in the Journal of Allergy and Clinical Immunology last month. The study points to the cold-sensitive nose—specifically extracellular vesicles inside nose cells—as the key immune response impacted by temperature. It turns out that a temperature drop of about 40 degrees Farenheit triggers a severe decrease in the quantity and effectiveness in EVs, decreasing the body’s ability to prevent infection. Ira speaks to the study’s lead author Benjamin Bleier, associate professor at Mass Eye and Ear in Boston, Massachusetts, about this breakthrough and the impact it could have on future treatments for respiratory illness.   By Hiding Their Blood, These Frogs Pull Off The Ultimate Disappearing Act Glass frogs have a superpower: If you look at them from above, they look like regular green frogs. But if you flip one over, you can see right into their bodies: hearts, intestines, bones, and all. As these frogs doze off, however, something changes: They disappear. Well, almost. A new study shows that the frogs can hide their red blood cells as they sleep, becoming expert camouflagers. Dr. Carlos Taboada, a biologist at Duke University, is a co-author on this study and he joins Ira to talk about the glass frogs’ tricks.   Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. Later in the hour, a Florida team looks for clues to how gophers feed themselves. It is the mystery of the underground root farm. You're not going to want to miss that. But first, redlining. The practice was pervasive in American cities, beginning in the 1930s through the late 60s. Maps were drawn specifically to ensure that black people were denied mortgages. and these discriminatory practices created a lasting legacy of economic and racial inequality, which still persists today. Less obvious, though, is how redlining has shaped nature, the urban ecosystem. A recent study found that previously redlined neighborhoods in Baltimore have fewer big old trees and less tree diversity. These findings are part of the Baltimore ecosystem study, a collaborative research project,

which has tracked the city's changing urban environment for the last 25 years. But it's not all bad news. The city of Baltimore has a comprehensive tree replanting initiative and is working with the community to restore the tree canopy. Joining me now to talk more about the trees and her research is Karen Burckhardt, assistant professor of entomology at the University of Maryland, based in College Park, Maryland. Welcome to Science Friday.

Oh, thanks for having me on. You're welcome. Let's talk about your research. Tell me how the trees in redlined neighborhoods compared to trees in other neighborhoods in Baltimore. Yeah, so first, if we're looking at the overall number of trees, we find 25 to 35 percent fewer species of trees for the same number of trees that we're looking across. So basically, you are getting about a third fewer species in neighborhoods that were previously redlined. Now, is that an important difference? It is important. So these trees are doing a lot for folks in the city. They are providing shade. They are providing habitat for all kinds of critters that use these, birds, insects. They also can provide the ability to mitigate storm runoff. And when we have fewer species in a given area, we are more likely to lose those particular individuals, kind of like a mutual

if you have a lot of different species that are in a particular community than when we have pests that come through or other diseases. Think about Emerald Ashboro or Dutch Elm disease. If everything in a given neighborhood is the same species, then we're going to lose all of those individuals all at once. So why has this disparity in the number and the types of trees between the previously red light neighborhoods and other parts of the city? Why has that continued for so many decades? Well, you know, it's really hard to say for sure. This is a correlational study, so we're not able to say that the reason we're seeing fewer trees is explicitly because of this policy. But there's all kinds of things that these policies represent.

Most importantly, they represent the investment of time and resources on the part of a city. So when we have policy decisions that are made that decrease home values in a particular, area, then it's probably more likely that there will be less investment in maintaining street trees, which represent a lot of time and effort to keep healthy. Then over time, you could see this impact on the overall diversity of trees and the number of trees. So another thing we found is that you're nine times less likely to find a large old tree in a potential location in one of these previously redlined neighborhoods. Wow. And big trees also help the young trees to survive too, don't they?

It's much harder to establish trees in an area that has very low canopy cover. And in these redlined neighborhoods, we tend to have lower tree canopy cover on average. And when that happens, you have higher temperatures. And those higher temperatures can make the conditions much more challenging for a young tree that's planted to kind of get their leg up and grow to maturity. Now the good news, the city has a campaign working with local community groups to replant trees, right? Which we're going to talk about in a bit. How will this research help the city reach its tree planting goals in the future? We saw this really interesting increase in the number of small trees that were being planted in previously redlined areas. So we get this really clear signature that the city is reinvesting. But we do have the, overuse or dominance of single species. We're getting a lot of planting of red maple specifically.

That kind of raises a little bit of a red flag that maybe we need to use studies like this to make sure that we are targeting our diversity goals in these previously redline areas so that they are going to be able to withstand pests and other diseases in the future and grow these canopies that can provide services for residents. Very interesting. What can other cities learn from your research cities besides Baltimore? So in Baltimore, we have red maple that is kind of the dominant species, but a lot of other researchers have found kind of similar reliance on single species in other cities.

I also want to point out that 239 other cities in the U.S. were redlined as well. And so this happened in many different cities. And so as they're planning these replanting campaigns, thinking about the legacy of these policies, how that might affect the potential survival of trees in these different neighborhoods, could be useful for them as a framework for making decisions about replantings there. Well, Dr. Burkhart, thank you for taking time to talk with us today. Thank you. Karen Burkhart, assistant professor of entomology,

at the University of Maryland based in College Park. Now that we've identified some of the problems facing Baltimore's tree canopy, I want to turn to some solutions. In 2007, the city of Baltimore set a goal to increase the tree cover from 20 to 40% by 2037. And since then, the city has been working closely with nonprofit community organizations to plant trees all over the city, especially in previously redlined and other. otherwise underserved neighborhoods. The nonprofit Baltimore Tree Trust has the biggest footprint in the city. They've planted over 16,000 trees so far. Joining me now to tell us more about the

organization's work is my guest, Ryan Alston Communications and Outreach Manager for Baltimore Tree Trust based in Baltimore. Welcome to Science Friday. Thank you so much for having me. You're welcome. This ambitious effort to restore Baltimore's trees is a couple of collaboration with community members, how do you work with communities to identify where and when the trees will be planted? Absolutely. So kind of what you spoke about earlier with Baltimore being the kind of blueprint for redlining, we here at the Tree Trust really acknowledge that, and we have the opportunity to really flip that and give communities and residents a voice when historically they've kind of been forgotten about and haven't had that input. And so when we're

planning for our trees. We're meeting with residents in their neighborhoods, in their communities, and giving them a chance to let us know what their needs really are. That's interesting because there was a study that came out in 2019 showing that Detroit residents didn't want these free trees provided by the city because they were not consulted in the process. There was a deep mistrust between the city's black residents and the mostly white nonprofits overseeing the tree planting. Is there some trust that needs to be rebuilt between local nonprofits and community members in Baltimore, too? Absolutely. I mean, we all have a running stroke at Baltimore Tree Trust that building Tree Trust is really in our name.

It's kind of the foreground of a lot of the work that we're doing when we're meeting with residents and having those conversations. Definitely understanding that every experience is valid and everyone is going to have a different experience with trees. and with city workers and city development. But it's really our job to connect with residents on that one-on-one basis and really listen. How do you do that? Do you go right out there into the neighborhoods and talk with people? Right before our season starts, we're working to identify community leaders. These are residents who've been in their homes.

They've seen the changes that has occurred throughout the years. And so we're using that as a launch pad to start these conversations. These stakeholders are able to connect us to different neighborhood associations or friends of groups or school leaders. We're able to really branch off of these connections from these longstanding community members and people who are really invested in seeing good change in their neighborhoods. When you talk to people, do they understand how important trees are to their neighborhoods? I understand summer is the best time to sell the benefits of trees to residents because of the heat. right? Absolutely. That's definitely one of the selling points. You know, we're walking with community leaders and residents around their neighborhoods and having that ability to say this block is 12 to 15 degrees

warmer in the summertime based on communities that have a lot more trees. That's also part of our job is to get them to understand why trees specifically in urban spaces and urban neighborhoods are so important. We're planting shade. We're planting trees that are going to help clear the air quality, and that always gets residents to start thinking about trees as something more than just arbitrary planting, but something that can really be part of the neighborhood infrastructure and this city infrastructure. I understand that one of the issues facing Baltimore's tree canopy is that there are too many red maples and the lack of tree species diversity. How do you select which types of trees are going to plant?

Yeah, so one of our founding statements, I think, at the Tree Trust is right tree, right place, right? We're understanding that, you know, there are different tree species that are going to do well in urban areas. So we work off of a palette of a few species that are proven to survive in urban settings and specifically their native species. But, of course, with climate change and we're seeing changes in temperatures and precipitation, that's causing us to think a little bit more. and switch our gears about the trees that we're planting. So switching more to some southern species that are able to survive in more of the warmer temperatures and a bit more of a drought. And really keeping in mind that tree diversity is important.

What advice would you give other cities who are working to replant trees? I think definitely one piece of advice is that community outreach piece and engaging residents at every level of tree planting. So we're giving residents the ability to have some input in the planting plans. We're giving them input in allowing them to come join us for a planting day. And we're also educating them on how to maintain and care for these trees long after we're gone. Well, I want to thank you for taking time to be with us today. And good luck to you to that great city of Baltimore.

Thank you so much. Ryan Alston, Communications and Outreach Manager for Baltimore Tree Trust, based, of course, in Baltimore, Maryland. We have to take a quick break and when we come back, digging for diet details about an unappreciated borrower, pocket gophers. This is Science Friday. I'm Ira Flato. Did you cozy with a book or movie over the winter holidays? Maybe as seems to be very popular right now, and intriguing who done it? Well, we're back with a different kind of mystery and it's all about gophers. Yes, there is a mystery about gophers. Here on the case is sci-fi sleuth, Christy Taylor.

Hey there, Christy. Hey there, Ira. You know what comes to mind when I think about gophers? Not a mystery, but that crazy gopher-filled movie, Caddysheck. You know what I mean? That's fair. A little slapstick, but it makes sense when you think of how these animals have been considered pests by so many people.

But they're also really impressive little animals, Ira. Their tunnel networks are absolutely massive, even for just one gopher. which is good for aerating soil. Ecologists consider them really important ecosystem engineers. Yes, and we like ecosystem engineers. Yeah, we do. And gophers are also mysterious. We don't know much about them because they almost never leave those tunnels,

not even to eat. Well, wait a minute. If they don't leave, then what do they eat? How do they eat? That's the million-dollar question, Ira. The leading theory has long been that they simply eat roots while they dig tunnels. Need more roots? Dig another tunnel.

But a team at the University of Florida looked into that, and they're now questioning whether there's more to the story. Their work was published in current biology this summer. I talked to Veronica Selden. She was an undergraduate when she did this project, and it was her idea in the first place. I also talked to her advisor, biology professor, Dr. Jack Putz. Here's Veronica explaining why she started looking at gophers, also known as pocket gophers, more closely. Pocket gophers are fossorial rodents. they spend nearly their entire lives excavating underground tunnel networks, and that excavation is an

energetically costly activity. But in terms of length, the tunnel systems can extend up to 160 meters. Wow. I was intrigued by the question of how they obtain enough food to sustain that activity. And we also wondered why they would invest so much energy into exercising. And excavating and maintaining and defending such extensive tunnel systems when they're solitary animals and theoretically don't need that amount of space. How do you go about figuring out then how much energy it takes to dig out a tunnel like that? We found an excavated into pocket gopher tunnels and took measurements of the tunnel radius and took soil samples from adjacent to the tunnel. And with that, we were able to calculate the soil bulk density. And using the dimensions of the tunnel, we were able to calculate using a pre-existing equation,

how much energy it would take to excavate a tunnel of a certain volume. Jack, as her advisor, as Veronica's advisor, what made you interested in this question about pocket gophers and the energy they consume or the energy that they need to do what they do? These are animals that are common in many places. You see their mounds, but you very seldom see them. Anything that's spending its life below ground is just intriguing. When we first went out to excavate a tunnel, we really had no idea what we were doing, and we were surprised at how deep we had to go before actually encountering a tunnel. and we notice that at that depth there are very few roots.

So they're down below the volume of soil with dense roots. And so it made us think about, well, where are they getting their food if there's so few roots down there? When they come to the surface to move out the material that they excavate from their tunnels, they're, you know, subjected to predators, birds and snakes and everything else eats pocket gophers. So they want to stay down low, but there's not much food down there. So at the end of the day, you dug out the tunnels, you did the math. Veronica, are they getting enough food from the roots that they eat when they're excavating these tunnels? We found that on average they are not getting enough energy from excavating.

to sustain that excavation. There is an energy deficit there. How big is the deficit? On average, nine kilojoules. So they're using nine kilojoules more than they're gaining. So how do we explain then they're digging their tunnel, they're chomping roots while they dig the tunnel, and that's not providing enough food for them? How do we begin to explain then where they're getting the rest of the energy they need to stay alive? We knew that roots would grow into sewer systems, a situation similar to a pocket gopher tunnel. So we looked into whether roots would grow into the gopher tunnels and perhaps if that could sustain their lifestyle.

So to test that, we isolated sections of tunnel, preventing gophers from entering by blocking all sides. Before the isolation period, we confirmed that there were no roots visible in the tunnel by filming inside with a borescope. after the period of isolation, we filmed inside the tunnel again, and we were graded with a vision of many roots growing into the tunnel. And we found that on average, this route in growth, daily root in growth, can account for 21% of their daily basal energetic needs. That's obviously not covering the entirety of their needs. So there is still an unsolved question of where are they getting the rest of their energy.

But it does paint a more complete picture. of how they're sustaining themselves. They're not just eating the roots once when they dig out the tunnel, but also more roots will grow into the tunnel for them to sort of snack on as they're going about their days. Yes. Jack and Veronica, you also in your paper suggests that this behavior could be considered farming by the gophers. They're creating conditions that allow these roots, their food to grow better than it might otherwise. Do you other biologists agree with this definition? That's been so interesting to see the range of reactions that basically go back to how you define farming.

Some people restrict farming to annual cropping of grains, but there's other kinds of farming that I would consider legitimate uses of that term where people who live in forested ecosystems farm forests. forests by promoting the growth of trees and vines and shrubs that they then harvest. In the case of pocket gophers, they're, as you said, they're creating conditions appropriate for the growth of roots that favor the growth of roots, and then they're cropping those roots. And actually, in the cropping process, they may be stimulating the production of new roots and new roots that are more digestible than the ones. that they excavated.

Because they're younger and they'd be more succulent. And so that together, for me and for about half the people who have contacted us, that does constitute a form of farming. But what's exciting is to think about an animal that's accepted as an ecosystem engineer. I mean, they are turning over soil. They are having a big effect on the ecosystem. But considering that animal is actively farming roots, I just find exciting. Veronica, how are you feeling about this research?

You got it published before you'd even finished your undergraduate? I mean, that must be exciting. That was definitely very exciting. I enjoyed so much getting to learn about these gophers. As Jack said, they are considered ecosystem engineers. I hope that even if we don't sufficiently convince everybody that they are farming, we can at least promote appreciation for the complex life cycles of these little animals underground. What kind of research would maybe further clarify what's going on with what they're eating?

I would like to see people doing more detailed work that would allow assessment of what roots are they preferring. We knew which species there were above ground, but not which species they're eating. We also don't know whether other fossorial mammals like pocket gophers are doing something that's very similar, but we suspect that they are. And almost everywhere in the world, there is an animal like this, but as far as I'm aware, no one has studied this aspect of their natural history. Having cameras, getting ideas of activity cycles, and we don't know, for example, why they're digging, when they're digging, whether the amount of tunnel excavation varies seasonally. There's so many mysteries about these animals. It's just hard to study an animal

that is below ground, especially that far below ground. But I think there's a lot of research that could be done and should be done. We hope that this project stimulates that kind of activity. Thank you both so much for joining me today. You're very welcome. Thank you again for having us. That was Veronica Selden and the University of Florida's Dr. Jack Puts. The research on pocket gophers appeared in current biology in July.

I'm Christy Taylor. You've probably seen, or maybe you're even using, an activated carbon filter or two. That's the filter in your water pitcher that you're probably, should change more often than you actually do. It's also that black filter in your air purifier, removing chemicals from the air. These are activated carbon filters, and they aren't just in your home. They're used in wastewater treatment and smokestacks. But what if we could create these filters using recycled materials? My next guest is working on this. She so far made activated carbon

filters from agricultural waste, meaning corn husks and orange peels. Joining me now to talk more about her research is Dr. Candice Abdulaziz, Assistant Professor of Chemical and Environmental Engineering at UC Riverside, that's based in Riverside, California. Dr. Abdulaziz, welcome to Science Friday. All right. Thank you, Ira. I'm glad to be here. As I mentioned before, you turn husks and stalks and leaves into carbon filters.

How did you land on? corn waste? Yeah, so corn waste is actually the top agricultural waste that's produced from the United States. I went to school in University of Illinois, so I'm very familiar with all of the corn fields around. And so that was one of the first initial problems that we wanted to utilize was to see if we can do something with all of the corn waste that's generated. And how do you turn corn husks into carbon filters? I know if you put a match to a corn husk, it's going to start burning and turning black, That's not what you do, is it? No.

So my laboratory at UC Riverside, we've actually developed a process that can break down corn husk and even citrus peels into solid carbon. And so what we do is we do some chemical modification of that solid carbon and creates this porous structure, which is then called activated carbon. And you can utilize activated carbon in all of these different cool applications. Now, let's talk about some of those cool applications. Name a few really good ones for us. Sure. So one of the ones that people are most familiar with is water filtration. In fact, my laboratory has been studying how we can modify activated carbon filters

from agricultural waste and utilize that to remove different water pollutants. Another way also is for air purification. So you can use activated carbon filters, say in your car, to purify the air that's going while you're driving your vehicle. Hmm. Now, I understand that you can actually filter out PFS, which is everywhere, right? When we first started working on the development of these activated carbon water filters, we were looking at the removal of different phenolic compounds, because those are typically what you see from industrial waste.

But we talked with some people at water municipalities, especially in Southern California, where we're located. And PFS seemed to be one of the things that were on a lot of these municipalities. qualities, mines in terms of removing that from wastewater. And so we've recently started looking at the removal of Phaas from wastewater. And in terms of trying to modify also the activated carbon properties so that we can do that effectively as well. You mentioned that you were turning orange peels into carbon filters using a similar process. I would imagine that being California, all those orange groves, that's where you get your peels from, right? Yes. Absolutely. So just around the

corner from my house, we have an orange grove. And we had the idea of we're in Southern California. We want to benefit the local industry here as well. And so we wanted to turn those orange peels, which are normally discarded or used for cow feed, and see we can also utilize that for activated carbon. And actually, one of my doctoral students just went to the citrus grope that's around the corner from my house and got like a trash bag full of orange peels. And we've been utilizing that for a lot of our experiments. They must have been more than happy to give it to you. Yeah, they were very happy. What are activated carbon filters typically made from, and why should we be using recycled ones coming up with new materials like you are, like corn husks or orange peels instead?

Typically, activated carbon is usually made from either coal or coconuts. Now, coal, I mean, And if we're trying to get away from coal as a energy resource, then it would be more advantageous for us to utilize something that's sustainable, like agricultural waste. Additionally, we utilize coconuts, but most of it is actually exported. And so the usefulness of developing activated carbon filters from agricultural waste, especially ones that are locally sourced, is that it can be sourced from the United States. Now, when can I get these filters in the store? I mean, I imagine you're just in the research phase, right? But people must be asking you all the time. Hey, I want to get some of this stuff. Yeah, there's actually a lot of interest into these renewable activated carbon filters. However, we're still doing significant amount of research. And in particular, we want to start upgrading them in terms of making them more beneficial for water treatment facilities. So making them and a controlled particle size, like granular size. In addition to that, we want to see what the effects

of these different growth seasons could have on the activated carbon, because that's probably one of the main issues is that you could have sort of a heterogeneity and sort of the growth cycle. And we expect that should also transform into modifying the properties of the activated carbons that's coming out of these agricultural resources. And so now we're trying to look into that as well. You sound like a carbon expert. What's on the carbon frontier, the carbon capture frontier that you would like to see happen? A big thrust of the research that we're doing is developing sorbents that are able to remove greenhouse gases like carbon dioxide and methane out of the air. And we're actually trying to utilize that as building blocks to make similar materials that we're making today out of fossil fuels. So that's something that's really exciting for us.

When you capture it in the carbon, does it stay in the carbon? I mean, could you use it to build other things with it and lock it up forever? So, for example, we have a material that can capture carbon dioxide and turn into a carbonate, which is basically solidified carbon. And so you can store it as a form of rock. That's something that's being studied right now. We're on the other end of it in terms of we're trying to make some uses out of the capture carbon. So capturing CO2 and methane and converting that into synthesis gas,

which is often a building block to make further things like gasoline or to make ethanol or ethylene, which can also be building blocks to make other materials like columners as well. Sounds very interesting, wishing you a lot of luck on this, Dr. Abdulaziz. Thank you for taking them to be with us today. Yeah, thank you for happy me. Dr. Candice Leslie Abdulaziz, Assistant Professor of Chemical and Environmental Engineering at UC Riverside. We have to take a quick break. and when we come back, a biological explanation for why we get sick when it's cold outside. It turns out

the nose knows. Stay with us. This is Science Friday. I'm Ira Flato. In case you haven't noticed, and who hasn't, we are now in the cold and flu season. It's the time of the year when it's cold outside, and you're more likely to see people sneezing and coughing, of course, the classic hallmarks of a respiratory infection. What's interesting about this time of the year, year is that it's usually assumed that the reason so many more people get sick is because we spend more time together locked up indoors. But new research out of Harvard Medical School and Northeastern University finds that there's a biological reason for the seasonal variation, and it all goes back to your nose. Joining me now to talk about this breakthrough is my guest,

Dr. Benjamin Blyer, Associate Professor at Mass Eye and Ear, and Senior Author, of this study. He's based in Boston, Massachusetts. Welcome to Science Friday. Hi, I are great to be here. You know, I am so glad to hear what you have learned because, you know, my mom always told me to bundle up outside in the cold or I'm going to get sick. But now along comes your research, and it turns out that mom was sort of right. The cold air does have something to do with it. Cold air when it gets into your nose. Tell us what you've uncovered. Well, yeah, it does turn out that our mothers and grandmothers were right all along, which perhaps is not surprising. But, you know, our study looked at the function of viruses as they get into the nose and how our body fights against them.

And you can kind of break our study down into two parts. The first is we actually discovered a novel innate immune mechanism or a way that our immune system fights off viruses as soon as they enter our nose. And then the second part of the study was to look at how that function is actually impaired when we're exposed to cold air. So the first part of the study asked the question, how does our nose fight and prevent viruses from infecting the cells? And what we found was a very interesting mechanism, which actually takes off on some research we had done several years prior with regards to bacteria. And essentially what we found is that when you inhale a virus, the front of the nose is

really the first part that the virus sees and impacts on those cells. That essentially alerts the nose that the virus is present because it binds to a receptor, which is called a toll-like receptor. Now, these receptors are actually evolutionarily coded in our bodies to already recognize these viruses, even if we've never actually been exposed to them before. But this sets off this cascade of events within the nose that results in three very important features of the immune response. The first is that the cells release what we like to call a swarm of extracellular vesicles. You can think of these as like little bubbles that are released from the cells into the nasal mucus. And we found that when a virus is introduced to the

nose, about 160% more of these little bubbles are released into the mucus. But it's not just the number of these bubbles that changes. It's actually the composition, how these little bubbles are packaged. So the first thing we found is that these bubbles are actually decorated on the surface with the same receptors that the virus uses to get into our cells. But the receptors are actually increased up to 20 times. So there's 20 times more of these receptors on the surface of these vesicles. So essentially, they act as little decoys. So the virus will bind to these vesicles and get mopped up before they ever have a chance to bind to the cells. So that's sort of the first way that these vesicles work. The second is that on the inside of these vesicles,

these bubbles, there's a whole array of complex molecules that actually kill the viruses. Now, we look specifically at a type of molecule called a microRNA, and in this case, microRNA 17, which is a microRNA, which has been previously shown to have antiviral effects. And we found that these vesicles have up to 13 times more microRNA-17 than before you were exposed to the virus. And so essentially, these vesicles bind to the virus because they act as these decoys, and then the virus is inactivated by the presence of this high concentration of microRNA. So, you know, this is a really cool mechanism because this is essentially what we're finding is that this is your body's immune system leaving the body itself to go into the outside

world to protect itself against the viruses before the virus can actually bind to the cell. The analogy we like to use is it's like a hornet's nest. So when the hornets are aware of an intruder, they swarm out of the nest to go attack the intruder before they have a chance to get into the nest itself. Wow, that's cool. Yeah, we thought so as well. Now, that was the first part of the study, but, you know, when we were thinking about this, we know that this whole response, everything that we're talking about is happening really at the front of the nose. You know, the front of the nose is the part of the body that's most exposed to the external environment, all the bacteria and viruses and fungus in the air and other

irritants, and we inhale about 10,000 liters of air a day. So you can see that the front of our nose is constantly being assaulted with this type of external irritants and, again, pathogens. But at the same time, we realize, well, not only is it exposed to what's in the air, but it's also exposed to the temperature of the air itself. And so if there's any part of the body that's going to be sensitive to the changes in temperature in our environment, it's going to be the front of the nose because this is exactly the area that first is impacted by that cold air before it the body has time to warm and humidify it so that by the time it gets into our lungs, it's actually at body temperature and at about 100% humidity. So that was what kicked off

the second part of our study asking, what is the effect of that cold air on the immune response? And the second part, you talked about what happens when it gets cold in your nose? Exactly. You know, we wanted this study to really reflect what happens in live people. And so what we did was we took little tiny temperature probes called a thermocouple. And using a small scope, we were actually able to guide this into the noses of healthy volunteers and measure the change in their nose in different places in their nose at different external temperatures. And what we found is that if you go from room temperature down to about 40 degrees, just that change in temperature externally, drops the temperature in the nose about five degrees Celsius or about nine degrees Fahrenheit. And so we then applied that same fairly modest drop in temperature to the studies that we just described about the immune response. And we found that in all three of these important effects were all impacted negatively by just this small change in temperature. So for example, the number of these vesicles that are released dropped by about 40%. Wow.

The amount of that protective microRNA dropped by about 25%. And the number of the receptors that we discussed dropped by about up to 75%. So in all of these different types of mechanisms, we have this decline in function. And what that translated to what we found in culture was that there was almost a doubling of the amount of virus able to replicate within the cells, again, just by this small temperature drop. And so essentially what this means is that when we're exposed to cold temperature in the front of the nose, the immunity, our ability to fight off these viruses drops by about half. And so essentially, it only takes about half as much virus to cause an infection in any individual as we get into these colder months. And again, this was even just a drop to 40 degrees.

That is, that's amazing. My question to you then is, now that we're dealing with COVID and our noses and we're wearing masks, if the mask keeps your nose warmer because you're recirculating, right, all that warm air, could that help you fight off a COVID virus as well as a cold virus? Yeah, so, you know, you hit the nail right on the head there, which is, you know, now that we understand this novel response, how do we use it to our advantage? to prevent infection. And I think what you described is really the most short-term actionable item that we can do. I think what we've shown is that we know that masks prevent us from being exposed to the virus,

but just as you said, now we believe that these masks also preserve this cushion of warm air in front of our noses and further reduce our ability to be impaired from the infection, which essentially means that all this time masks have probably been acting in two different ways. And that probably responds to why they're so effective with prevention of viruses. So what are the implications of this discovery, then, for treating upper respiratory infections? Well, you know, this discovery really, as I mentioned, pertains to the innate immune response. This is the immune response that prevents us from getting the infection in the first place. This is different than the adaptive immune response, which is, for example, what happens when we get vaccinated.

That's why vaccinations take weeks to kick in for our amy. antibodies to develop. So what we're talking about here is really prevention as opposed to treatment. What we've found is that essentially when the body is convinced that there's a virus present, it kicks off this entire response. So if we can develop topical sprays, for example, that mimic the presence of a virus without the actual pathogenicity or the injurious part of the virus, then we can fool the nose into thinking a virus is present and increase the amount of these protective vesicles, even without having to actually be exposed to the virus. Well, I want to thank, this is great. Great to learn. Great to have you on and tell us about it.

Thank you for taking time to be with us today. Oh, it's been my pleasure. Dr. Benjamin Blyer, Associate Professor at Mass Eye and Ear and Senior Author of this study, he's based in Boston. Have you ever heard of a glass frog? There are these little frogs found all over Central and South America. And what's incredible about them is that they look green from the top. But if you flip one over, it looks like, you guessed it, glass. You'll see their hearts, their intestines, the bones, everything. But as these frogs doze off, something almost magical happens. The frogs disappear. Well, almost. Here to tell us how these frogs pull off such a neat magic trick is my guest, Dr. Carlos Tabawata, biologist at Duke University.

based in Durham, North Carolina. Welcome to Science Friday. Thank you so much for having me here. You're welcome. Let's get into the details because this is some amazing trick. How do the frogs do it? What we found basically is that the animals can pull out 90% of the red blood cells when they sleep and basically aggregate all of those cells inside of the livers.

Basically, they remove most of the pigments that would normally create an opaque animal, like us, for example. That's really interesting. Why does it only happen when they're sleeping? We're still trying to figure that out. What we know is that when they sleep, in a way, they are less aware of predators. They become transparent, and they reduce their metabolic rates. In a way, it's a trade-off.

They can do it while they sleep if they stay motionless without a big oxygen supply. When they're awake, they need to meet their metabolic needs because they start chasing, praise, they start breeding, vocalizing. and they need more oxygen. So it's then when they become opaque and cannot pack their red blood cells anymore. Is it possibly a defense mechanism for when they're sleeping

when they get transparent that they're not seen so easily by predators? That's interesting. I mean, there's some evidence that shows that transparency can help them camouflage. And that's what we also found. I mean, the optical properties are like a leaf.

So basically they match the vegetation perfectly where they sleep during the day. There's evidence that some predators might not see them during this time because in this case transparency works really well because we are used to seeing animals in terms of reflected light. All of the colors that we see in nature come from the way that light reflects on a surface. In this case, we need to think about animals being viewed through leaves and also like on reflected light. So this is a really complex form of camouflage that might help. When you discover that all the red bloods were sort of heading to the liver. How surprising was that for you? It was amazing. We had never

think anything like that because transparency was a mystery in glass frogs. But then after we found out, we started doing some research and discovered that there's some sort of ancestral mechanism in frogs. There's some evidence that other European common frogs under really specific experimental conditions, that induce some sort of, like, induced coma in really well, like, oxygenated environments and really cold temperatures, they can store, to some extent, some red blood cells. They do that, and in a way that could mimic hibernation or torque or physiology. In this case, it was really surprising to see that glassfrax could push this to the limit, go from like around 40% storage to like 90% of the whole pool,

and they could do it like even at high temperatures. And every day on a circadian rhythm basis, that was the most interesting thing. Not only the amount that they could store in the levers, but also that they could do it at really, really high temperatures and daily. That's amazing. You know, I imagine if you're packing a whole lot of red blood cells into one tiny space, as you said, that's what happens.

Couldn't that cause some problems? I mean, is the liver, their liver especially made to be able to handle all of this? In a way they do, the liver increases its volume by like 40% when they packed all of their red blood cells. There's two distinctive traits in the levers. One is that they are covered with mirrors like structures that are millions, millions of nanocrystal packed inside of a tissue that basically helped them reflect most of the light. so we cannot see the red blood cells through the livers. And the other thing that is important is that in many other vertebrates,

the livers are pretty distensible. They have capillaries, which in the livers are called sinusoid. That is the place where most of the interchanges of metabolites occur. The fact that they do it in a way requires other adaptations that allow them to aggregate all of the red blood cells without triggering a clot. That's what would normally happen to other animals for those concentrations and packing of red blood cells. But somehow the frogs can do it without getting a blood clot.

They can do it. They can do it pretty well. While at the same time, they can still clot when they need it. Even when they are sleeping in their liver, everything is fine. But if the animals are injured, for example, by a predator, they can still clot luckily. So their whole coagulation system is functional. But they can in a way split two functions. One is clotting normally and non-clotting pathologics.

Well, if they can store all this blood in the liver without it coagulating and they can do all this magical stuff with it, is there anything that we could apply to human medicine to learn from the fraud? Oh, certainly. Normally when there are like pathological clots, people are treated with anticoagulants and these anti-caucigulants, sometimes they can induce some excessive bleeding in patients. We don't really know yet the mechanism that this frog used to basically avoid the formation of a big clot. But certainly they deserve some research to figure it out.

They clearly have a way to compartmentalize different pathways of calculation, and they can somehow prevent it probably using a local anti-coagulant. And so we need to find those genetic tricks that probably do something translational. that is something that we are exploring right now and hopefully we'll have some results in the near future. Okay, well, you come back and tell us about it, okay? When you find that? I'll be happy to. Well, thank you, Dr. for taking time to be with us today.

Of course. Thank you for having me here. Dr. Carlos Tapawata is a biologist at Duke University based in Durham, North Carolina. If you'd like to see these frogs hide their blood, visit sciencefriety.com slash glass frogs. Before we go, though, we want to give a big Science Friday welcome to our new listeners at KALW in San Francisco. Welcome aboard. Have a great weekend. We'll see you next week. I'm Ira Flato.