![[BONUS] How the moon causes tides and ancient viruses lurking in your DNA: Tiny Show and Tell Us #7 Artwork](https://www.buzzsprout.com/rails/active_storage/representations/redirect/eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaHBCS0hiSmdnPSIsImV4cCI6bnVsbCwicHVyIjoiYmxvYl9pZCJ9fQ==--4c01c60d9d7510f2dc70a43c79c2c4201f33f5e2/eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaDdDVG9MWm05eWJXRjBPZ2hxY0djNkUzSmxjMmw2WlY5MGIxOW1hV3hzV3docEFsZ0NhUUpZQW5zR09nbGpjbTl3T2d0alpXNTBjbVU2Q25OaGRtVnlld1k2REhGMVlXeHBkSGxwUVRvUVkyOXNiM1Z5YzNCaFkyVkpJZ2x6Y21kaUJqb0dSVlE9IiwiZXhwIjpudWxsLCJwdXIiOiJ2YXJpYXRpb24ifX0=--1924d851274c06c8fa0acdfeffb43489fc4a7fcc/Tiny%20Matters%20cover.png)
Tiny Matters
Take a dive into the genes, microbes, molecules and other tiny things that have a big impact on our world with Tiny Matters. Join scientists Sam Jones and Deboki Chakravarti as they take apart complex and contentious topics in science and help rebuild your understanding. From deadly diseases to ancient sewers to forensic toxicology, Sam and Deboki embrace the awe and messiness of science and its place in the past, present, and future. Tiny Matters releases new episodes every Wednesday and is brought to you by the American Chemical Society, a non-profit scientific organization advancing chemistry and connecting the broader scientific community. Tiny Matters is produced by Multitude.
Tiny Matters
[BONUS] How the moon causes tides and ancient viruses lurking in your DNA: Tiny Show and Tell Us #7
In this episode of Tiny Show and Tell Us, we break down the complicated science of tides and why some places have massive tidal swings while others do not. We also cover the role of ancient viral DNA in our genomes, and how it seems to be making us less responsive to cancer treatments like chemotherapy.
We need your stories — they're what make these bonus episodes possible! Write in to tinymatters@acs.org *or fill out this form* with your favorite science fact or science news story for a chance to be featured in a future episode and win a Tiny Matters mug!
Here's the tides video George mentioned. The rest of the references and transcript for this episode can be found at acs.org/tinymatters.
Welcome to Tiny Show and Tell Us the bonus series where you write in with your favorite science story, fact or piece of news. We read your email aloud and then dive deeper. I'm Sam Jones, the exec producer of Tiny Matters, and I want to give a big thank you to science writer and chemist Anne Hilden for doing the research for this episode and so many episodes before it. Today I'm here again with science communicator George Zaidan and so many episodes before it.
Speaker 2:Today I'm here again with science communicator George Zaidan. Hey, Sam, great to be here. And before we get into things, just a reminder that Tiny Matters is always looking for you to write in, because that is what makes future episodes possible. You can email us at tinymattersatacsorg or click the Google form link that we put in the episode description. All right, let's do this Now. You went first in episode six, so I can volunteer as tribute this time lovely our first one comes from will.
Speaker 2:So will writes. Did you know that the largest tidal swing in the southeastern united states is in coastal georgia? During a king tide, the difference between low and high tide can exceed 10 feet. This is due to something called the georgia bite that's spelled b-i-g-h-t, not B-I-T-E, where a lot of the wave energy from North Carolina down to the tip of Florida flows inwards toward the Georgia coast. Since the continental shelf extends further out into the ocean than most other states, the waves are smaller, but the tides are much bigger. And then Will shares a link for context.
Speaker 1:First off can I just say 10 feet yeah.
Speaker 2:That's wild yeah.
Speaker 1:That's wild. Yeah, because I grew up near a river Was not the case.
Speaker 2:Yeah, yeah.
Speaker 1:It's like a whole story. It's a whole story Of a building.
Speaker 2:Yeah, exactly, it's a whole story of a building and I think, like for me, I think we just got to start with the tides, because tides are way more complicated than most people realize and most people know two things about the tides. You know this, I knew this. They're caused by the moon and there's two per day, right, too high and too low.
Speaker 1:Yeah.
Speaker 2:So I watched some videos online to like try and figure out what causes the tides and how the moon causes the tides, and there were no satisfying explanations until I found a video on a channel that I want to shut out because it was really good. It's called Water Lust. It explains the whole thing and I'm going to give you the super condensed version of it. So, unless you are driving right now, listening and driving, close your eyes, picture the earth on the left and the moon on the right and picture them just still being held by large, invisible hands. In real life, they're orbiting each other. But this is just a simplified picture. If you let go, if those hands let go, the earth and the moon will be pulled toward each other because of gravity. Right? How did you picture that happening? Did you picture like two billiard balls moving towards each other?
Speaker 1:Yeah.
Speaker 2:Okay, so let's complicate that picture. Oh no, I know.
Speaker 1:I like how also you started off by being like I think people feel like they understand tides and I was like I am not one of those people, so let's do this.
Speaker 2:So okay. So gravity gets weaker the further away. Something is right, and this is the wild one gravity affects every point on Earth independently. So what that means is like gravity is pulling on the oceans, gravity is pulling on the lands, gravity is pulling on the trees. It's not that gravity pulls on Earth as a whole, it's that gravity pulls on every single technically every single atom on Earth independently. So close your eyes again. Go back to the picture of the Earth and the moon being held by invisible hands right. Picture. Close your eyes again. Go back to the picture of the Earth and the moon being held by invisible hands right. Picture the moon's gravity pulling on all the different points of Earth. And, just to simplify it, let's talk about four different points. The point where the Earth is closest to the moon let's say that that's some ocean and some land. Do you think that gravity will pull strong there or weak there? The moon's?
Speaker 1:gravity. I would think it would be stronger.
Speaker 2:Yes, that'll be the point where it pulls the strongest, because it's closest to the moon. Yeah, now think about the opposite point of Earth, the furthest left point in your mind. The gravity there will be Less Weakest right, exactly yeah, now, this is the tricky one. Imagine the top and the bottom of Earth in your mind. Oh no, yeah, I know and remember that the moon is a lot smaller than Earth. What will those points of Earth do, the top and the bottom?
Speaker 1:I'm going to sound so dumb when I say this Like pull centrally.
Speaker 2:Yes, no, that's exactly right.
Speaker 1:So the top Wait, that's so weird, I know.
Speaker 2:The top part of the Earth, the ocean at the top part of the Earth will be pulled towards the moon, which is like down and to the right in your mental image, and the opposite will happen in the bottom of the earth the ocean will be pulled up and to the right. Right, yes. And now let's add one last last piece of the puzzle, I promise okay, is the rock of earth, the solid part of earth, so not the oceans. Right, that is going to get pulled towards the moon, but because it's rock, it's not going to get deformed like the ocean right Right.
Speaker 2:So overall, what happens is that all these different parts of Earth, they accelerate toward the moon at different rates. So the ocean on the right side of Earth is going to bulge outward toward the moon. The ocean at the top and bottom of Earth are going to be compressed downwards because they're being pulled down towards that tiny spot of the moon. And this is the most confusing one, because the rock of Earth is moving towards the moon faster than the ocean on the left side. The ocean on the left side gets left behind relatively in space, so it bulges out.
Speaker 1:Weird. Right, you really need like an animation to understand this, yeah, and we will link to this video, for sure, so people can really look at it.
Speaker 2:And highly recommend it. So overall, the oceans of Earth become an ellipse right, and you have the sphere of the rock that rotates inside of this ellipse. So that gives you two high tides, which are the bulges on the left and right, and two low tides, which are the compressions on the top and bottom. Whoa, and as if that were not complicated enough, other things in our solar system also cause tidal forces. The sun will also cause that. So you get overlapping tidal forces of different celestial bodies and you get very, very complicated tides high, low. Sometimes you get like two times a month where the tides are extra high and two times a month where they're extra low. And that's not even considering coastal geography.
Speaker 2:So Will's whole email was like the Georgia Bight has exceptionally high tides, a difference between high and low tide in the southeastern United States, and that's basically because we're going to super shorten this explanation. That's basically because you have a bay. It's a very, very large bay and the rising water gets concentrated. The high tide gets concentrated in the center of that bay and so you get exceptionally high and low tides. The same sort of thing happens in the place with the highest tides on earth, which is the Bay of Fundy in Canada. That is amplified by a whole other thing. That's resonance that we're not gonna get into. It's all covered in this video which we will link to. But I, from thinking that I sort of understood tides, now I'm like, wow, I really don't know a thing about tides actually.
Speaker 1:I think I was always afraid of trying to understand tides.
Speaker 2:Yeah.
Speaker 1:But this actually makes me feel better, george. So thank you. That was a good explainer, and thank you to whoever made that video. Also must've been a good explainer. Now, I know it's not magic, no, I never, thought it was magic.
Speaker 1:But I think I was always like, oh, this is just a lot of stuff that has to do with space. Yeah, really confuses me. For some reason, deboki and I sometimes talk about this, where we're like write a script that relates to something in space or answer a question and we're always like good job, good job. I know that was hard for you mentally and I think, because I knew that the moon was involved, I was like this is mess with me and I'm not going to understand it. And I feel, like most things like, if I don't understand them, I'm so dedicated trying to figure it out and for some reason with tides I was like can't do it. And now it makes more sense. I still have, of course, there's like always more questions and answers with these kinds of things for me, but it actually makes a whole lot more sense than whatever I was trying to like assume it was in the past.
Speaker 2:Yeah, yeah. I think that the thing that trips most people up is like OK, you know that the moon pulls on the Earth's oceans, so then why does the ocean on the back of the Earth, the far away from the moon, stick out, away from the moon?
Speaker 2:Shouldn't the moon be pulling that toward itself too, like that's the thing, that really trips most people up, and this was the best explainer I've ever seen on that front. So yeah, we'll link the video. It's great. You should watch it. It's 14 minutes about tides, but who doesn't love to go deep?
Speaker 1:Yeah, for sure, Awesome. Well, thank you George.
Speaker 2:Sure.
Speaker 1:I'm going to talk about something completely different that I'm less afraid of.
Speaker 2:Excellent.
Speaker 1:Which is odd because I'm going to talk about ancient viral DNA. Okay, so this one, this email, was from listener Rick from Broomfield, Colorado. So Rick wrote in sharing news aboutid parasite. A lot of its DNA almost I think the majority of its DNA actually comes from these really large ancient viruses. And so Rick saw that, or heard that, and wrote in saying I have to share this news about how ancient viral DNA seems to help cancer cells grow and survive treatments like chemo.
Speaker 2:That's wild.
Speaker 1:Let's talk about this ancient viral DNA.
Speaker 2:Yes.
Speaker 1:More specifically, human endogenous retroviral elements, or HERVs. I don't know if people in the field call them HERVs, but it's H-E-R-V-S, so I'm calling them HERVs. Apologies to cancer researchers if that's not how you guys do things, but we're going to shorten it so HERVs. Not how you guys do things, but we're going to shorten it so herbs.
Speaker 1:So I think really this requires a short explainer on what it means for something to be endogenous and what a retrovirus is. So first retroviruses. So these are viruses that can use their RNA genomes, so their genome made up of RNA, but they can use it to actually make DNA, so typically we have DNA codes for RNA. In this case, the viruses will actually get their RNA into a cell and then trick the host cell into expressing that as DNA to make viral proteins and so they hijack the cell's machinery, use it against itself to make copies of a virus Got it.
Speaker 1:Very sneaky, real bummer. So because that new DNA is now present in the nucleus of the cell, it can be replicated and carry on each time the cell divides. And that's why retroviruses like HIV can't be eradicated from a patient. Once they're infected, they can only be controlled because they're in there, they've integrated into your genome. What happens is HIV gets in a protein called reverse transcriptase. It actually transcribes the viral RNA into DNA and then that DNA is brought into the cell nucleus, where your chromatin is, which is really just like your bunched up DNA. Hiv has this protein called integrase and it integrates the HIV DNA into your DNA. And so this is very similar. I mean like, depending on what the virus is, there's going to be variations in what proteins or enzymes are playing a role in that integration and like the other processes to lead to the integration Totally. And then when we talk about endogenous because again we're talking about human endogenous retroviral elements or herbs yep, yes, uh, the word endogenous refers to something that arises from within an organism.
Speaker 1:So, for example, if someone says, oh, endogenous expression of a protein, it means your cells are producing that protein. Got it okay, so back to herbs. So these are bits of viral dna that have been incorporated into the human genome, even though they originally, of course, came from viruses. So these leftover bits are sometimes simply called endogenous retroviruses or retroviral fossils, which I actually kind of like.
Speaker 2:Yeah, that's a great name.
Speaker 1:Yeah, yeah, and they make up about 8% of our genome.
Speaker 2:What.
Speaker 1:Yeah, which is a lot more than I thought.
Speaker 2:Wow.
Speaker 1:Yeah, yeah, yeah. And just because they make up 8% of our genome doesn't mean they do things, but it's still. That's a lot of real estate.
Speaker 2:That's a huge amount of. I mean, I remember hearing at some point that the difference between two different species can be a couple of percent right of DNA, and so this is way more than that, Wow, yeah.
Speaker 1:And actually it's interesting that you just mentioned that because cool fact for you endogenous retroviruses provide some really compelling proof that humans and chimpanzees shared a common ancestor, since we have many of these bits of viral DNA in the exact same places in our genomes.
Speaker 2:Wow Okay, that is super fascinating.
Speaker 1:Yeah, and so, like I just kind of hinted at, like, not all this is super important. Some of it's considered, quote junk DNA, but you know, some of it does serve functions in our body like placenta formation and some immune response stuff as well. So there are a bunch of different studies, articles that have looked at herbs, herbses roles in human health. Researchers have found that stretches of viral DNA that are embedded in the human genome can produce proteins that actually can help block infection by viruses. What? Yes, yes, yes, yes.
Speaker 2:Why how?
Speaker 1:It's pretty wild. I wonder if it was a thing where it was like a viral survival, like there's so many viruses that other viruses compete with that that's where my brain goes.
Speaker 2:Yeah right, it's almost like you know.
Speaker 1:Survival of the fittest virus? Yeah.
Speaker 2:And like people who come into a house and they're like okay, done, nobody else can survive here. We're going to like, arm the security system. That was a really weird metaphor. I don't know why I went there, but yeah, it's like last of us viruses. What's last of Us?
Speaker 1:The Last of Us. I don't know what that is the show slash video game that it was adapted from. That was like a sensation. I don't, I don't really Wow.
Speaker 2:George, I don't video game because when I was a kid I got addicted to them and it was bad and so I quit.
Speaker 1:So I don't video game, but they turned it into an HBO series and it's incredible and they won a lot of awards and it's probably one of my favorite things I've ever watched. But it is kind of scary. It does involve some zombies, but it's essentially about a pandemic that's caused by a fungus.
Speaker 2:Oh.
Speaker 1:And I can't believe that we're having. Ok, we have to get back to retroviruses. George you need to look up the Last of Us after this.
Speaker 2:I'll go watch it. Ok, I I'll go watch it, okay.
Speaker 1:So where were?
Speaker 2:we. I feel like I've interrupted you like 16 times.
Speaker 1:It's okay, it's okay, Retroviruses, HERVs we're getting back to Rick's news. So researchers at the University of Colorado at Boulder have found a link between HERVs and cancer cell survival. So cancer cells they're already known to express a lot of genes that they're really not supposed to.
Speaker 2:Right, and that's part of what makes them dangerous.
Speaker 1:It's just not entirely clear what's turning on that expression Like why are they doing this? And it turns out that viral DNA could actually be playing a role. And so what this group did was they analyzed data sets of gene activity in 21 different cancers and they looked specifically at activity in these ancient viral sequences, these HERVs, and then they did an experiment using CRISPR to cut six of those sequences out of colorectal cancer cells just to see if there would be any effect if you took those out, in these cells being more susceptible to treatment. So in removing one of those sequences in particular, it seemed to turn off a DNA repair sequence and that made the cancer cells more likely to die by DNA damaging therapy, including radiation.
Speaker 1:So that's part of the thing is, like these cells cancer cells I mean, there's so much variation and it depends on the cancer but a lot of times it's like these cells are what is the right word for it Like they're tough, right, like they have these mechanisms that normal cells wouldn't to prevent die off, and so like they have these proteins and things that will actually help with DNA repair. So you know, you hit them with radiation and there's stuff in there that would repair what these researchers are finding is that some of the sequences that are coding for things that make these cells so tough if you get rid of them they will be easier to kill off. And yeah, and those sequences not always, but it seems like a lot of them come from this viral DNA that's integrated.
Speaker 2:Fascinating.
Speaker 1:Yeah, and so learning more about gene expression in cancer cells could really pave the way for more targeted therapies in the future. That would make standard therapies like chemo work more effectively. Like if you knew you were coming up against some virally encoded protein that's going to make immunotherapy or chemotherapy less successful. Like could you also block that protein or could you find a way of silencing the expression of endogenous retroviruses themselves? So it's very exciting. It's one of those things you're like I don't understand. Why are these cells not responding? Like this should be killing them.
Speaker 2:Yeah, yeah. But you have these ancient sequences of viral DNA that are helping those cells produce proteins that are then making it so these therapies are less effective. So, like, how can we mess with? That is kind of what what researchers are now thinking. That's super cool. It's especially cool because it sounds like this experiment kind of in one stroke illuminated something fundamental about what's happening and also provided maybe an avenue for like us to make our cancer treatments better.
Speaker 2:Yeah, absolutely, Very cool. All right, that's it. Thanks for tuning in to Tiny Show and Tell Us a bonus episode from Tiny Matters, a production of the American Chemical Society.
Speaker 1:To be featured in a future episode. Send us an email with your tiny show and tell at tinymattersatacsorg, or click the Google form link in this episode's description. See you next time.
