Today, you’ll learn about how carnivorous plants evolved from their more peaceful ancestors, how there’s an apparent difference in the frequency and severity of head injuries between male and female athletes, and about a new theory regarding the cause of Alzheimer’s.
Today, you’ll learn about how carnivorous plants evolved from their more peaceful ancestors, how there’s an apparent difference in the frequency and severity of head injuries between male and female athletes, and about a new theory regarding the cause of Alzheimer’s.
Plants that eat flesh?
Male and female concussions are not the same.
Hope for Alzheimer's research.
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Find episode transcripts here: https://curiosity-daily-4e53644e.simplecast.com/episodes/hungry-plants-concussion-confusion-an-alzheimers-theory
HUNGRY PLANTS, CONCUSSION CONFUSION, AN ALZHEIMER’S THEORY
NATE: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from Discovery. Time flies when you’re learnin’ super cool stuff. I’m Nate.
CALLI: And I’m Calli. If you’re dropping in for the first time, welcome to Curiosity, where we aim to blow your mind by helping you to grow your mind. If you’re a loyal listener, welcome back!
NATE: Today, you’ll learn about how carnivorous plants evolved from their more peaceful ancestors, how there’s an apparent difference in the frequency and severity of head injuries between male and female athletes, and about a new theory regarding the cause of Alzheimer’s.
CALLI: Without further adieu, let’s satisfy some curiosity!
[SFX: Whoosh]
NATE: Calli, do you ever wonder what would happen if sheep turned the tables and started wearing coats made out of our hair?
CALLI: Nate, I can safely say I have never wondered that.
NATE: It's not crazy. I mean some plants have human-like tendencies.
CALLI: Oh yeah? Is there a plant-Nate out there making plant knives and cooking plant steaks?
NATE: Not quite, but of course, there ARE carnivorous plants. And it’s really kinda interesting how they evolved from your typical plant, which only eats dirt and... the sun, I guess?
CALLI: Well, when you say it that way, photosynthesis sounds a lot cooler!
NATE: Carnivorous plants have long been an object of fascination for botanists and the morbidly curious alike.
CALLI: And lovers of Mario Brothers, or musical theater.
NATE: Of course. But you know, before Darwin published a book on carnivorous plants in 1875, most people refused to believe they were real. Eventually of course, people accepted them, but they quickly became the subject of pop culture horror stories.
CALLI: “Feeeeed me Seymour…”
NATE: Exactly!
CALLI: So, how did these plants get the taste for flesh.
NATE: For a long time, we didn't know. Scientists were curious, but our best resource—fossils—didn’t have any clues. But then they figured out a way: DNA sequencing. When they examined the genes, looking for those that could be used to go carnivorous, they learned that plants have evolved to be carnivorous at least twelve separate times in history.
CALLI: Wow. So what would cause a plant to go from eating sun to EATING SOULS.
NATE: They got hungry! There are eight-hundred carnivorous plants that exist today, and many of them can be found in areas that lack nutrients like nitrogen and phosphorus, think bogs, thin soils, nutrient-devoid swamps. And while the soil lacks these nutrients, the insects that fly around in these areas are packed with protein, phosphorus and nitrogen, filling that essential gap.
CALLI: Ok, so what methods can a plant use to go from photosynthesizing, to “plotting murder.”
NATE: Boy, you’re really having fun with this. Well carnivorous plants are either passive or active. Passive carnivorous plants, like pitcher plants, create a deadly trap, like a slippery rim around a cavity of digestive fluid, or a sticky leaf, and simply wait for insects to fall in. Active plants do a bit more work to trap their prey, they have leaves that can curl and push insects into sticky parts of their trap, or they have tentacles that can wrap around insects. Of course, you’re probably familiar with the Venus Fly Trap which clamps down on its prey. Each of these plants, whether active or passive, uses their leaves to get nutrients, unlike most other plants which use their roots.
CALLI: So the stuff at the top got the job of the stuff at the bottom, like if I started walking around on my hands.
NATE: Sure, yeah! And, as you can imagine, the way to make that happen is to repurpose genes the plant already had. You’ve already got those genes for digesting and absorbing nutrients. Why not make them work up in the leaves instead of down in the roots?
CALLI: Movin’ on up! Movin’ on up! So, what’s the process here? How does it all go down?
NATE: So, in the 1970s researchers recognized that the digestive fluid of some of these plants use the same enzyme that other plants use as a weapon to fight off insects, bacteria, and fungi.
CALLI: Huh. One plant’s sword is another plant’s steak knife I guess.
NATE: Exactly, and the more they looked, the more chitinases they found.
CALLI: Chitinases?
NATE: Chitin ... ases. Enzymes that break down chitin, which is what insect exoskeletons are made of.
CALLI: Ahhh, I see.
NATE: But breaking down the exoskeletons isn’t enough. Those nutrients then have to make it inside the plant. And while roots are great at this, leaves usually aren’t tasked with this job.
CALLI: Well it is a good economy for switching careers.
NATE: The transporter proteins also moved from the roots to the leaves. There was a big difference though. Whereas in roots, they were always working, in leaves they wait till there’s a fly providing some nutrients before they let the nutrient shuttles leave the station.
CALLI: Sounds like they’ve got an efficient manager, scheduling their time, keeping resources from going to waste. And it sounds like the manager decided these genes would be served better in the executive suites upstairs, rather than down in the cellar. So, they ordered a little gene mutation.
NATE: That’s what the researchers think. And while this process has happened independently a number of times, it seems that it always happens by repurposing one of just a handful of ancient enzymes.
CALLI: Well what would that mean?
NATE: While it's possible for different plants to mutate to become carnivorous independently, there are only a few paths to get there, and it involves repurposing what they already have.
CALLI: I have a new respect for carnivorous plants, but I’ll be honest...
NATE: Still hoping to see a lamb in a human hair coat?
CALLI: If only to post on Instagram!
[SFX: Whoosh]
CALLI: Nate you’re a sports guy right?
NATE: Go...tigers?
CALLI: Well even if you aren’t I’m sure you’ve heard of all the news surrounding athletes and concussions.
NATE: Even just reading about it makes my head hurt.
CALLI: Turns out it’s just the tip of the iceberg, when it comes to female athletes in particular.
NATE: How so?
CALLI: Over the last ten years or so new studies have found some pretty concerning data that shows female athletes are not only more susceptible to concussions and whiplash, but also more likely to suffer in the aftermath of the injuries.
NATE: You know I’ve heard a lot about concussions, but what’s the actual brain science behind the injury?
CALLI: We all know the brain is a pretty delicate part of our bodies. And even though it’s encased in something as hard as our skull, there’s still only a thin layer of fluid protecting it on the inside. When our heads take a big impact, like, say, falling to the ground after a rugby tackle, or heading a soccer ball - the force of the impact can penetrate deep into the gray matter of our brains.
NATE: Just from heading a soccer ball!? I see people do that all the time.
CALLI: What’s especially interesting about soccer in particular is that a study focusing on it found women were much more likely to get an injury when making contact with an object, like the ball itself, whereas men’s injuries primarily came from contact with other players.
NATE: Could it be from different styles of coaching? I had a few coaches in middle school who were pretty confused as to what kind of “football” we were playing.
CALLI: It could be coaching, or something else entirely. There are some anatomical differences in the head and neck area, the way certain hormones peak at different times for the different biological sexes, or it could be as simple as there's a higher likelihood for women to report an injury than men. All of these have been studied, but there’s no definitive answer, yet.
NATE: So many options. This is scrambling my brain.
CALLI: You mean it’s giving you axonal damage?
NATE: Sometimes I think you’re trying to confuse me on purpose.
CALLI: I’ll explain - the neurons of our brain each have a fiber called the axon that helps transmit signals between cells. It’s believed that damage done to axons is the primary culprit for the cause of concussions.
NATE: Damaged Axons sounds like it could be a really cool punk band.
CALLI: Each axon has tiny tunnels that carry proteins to help it function properly. If one of those tunnels, known as a “microtubule,” is damaged - then that protein will build up and cause a break. And once an axon is disconnected, it’s gone forever.
NATE: Disconnected Axons doesn’t quite have the same angst to it. Maybe more of an emo thing. Sorry, distracted, so, studying the differences in axon damage would probably give us better insight into this issue.
CALLI: That’s the hope. It could also help us determine how to manage recovery after an injury.
NATE: How would you study something that small inside the brain?
CALLI: Through the wonderful world of blood markers!
NATE: What are you even talking about?
CALLI: Sometimes, parts of the disconnected axons will leak into the bloodstream, so if you’ve got a lot of those, that’s probably not good. They’re not a hundred percent sure what the exact relationship is yet, but blood studies on pro ice hockey players have shown axon protein data that could help predict recovery outcomes.
NATE: It sounds like a lot of the science around this issue is still pretty new.
CALLI: And that’s the biggest problem - there’s just a lot fewer resources dedicated to studying injuries in female athletes. Although some organizations are now beginning to see the necessity for studying the issue separately between men and women.
NATE: I remember seeing something about a new NINDS funding package.
CALLI: That would be the U.S. National Institute of Neurological Disorders and Stroke. They’re putting six point eight million dollars into two pretty big projects solely dedicated to studying the differences between sexes when it comes to concussions. Let’s just hope the researchers can put their heads together to find some fixes.
NATE: That joke was...uhhh...
CALLI: Oh come on I let you get away with like three bad puns this episode.
[SFX: Whoosh]
NATE: Calli, what do you know about Alzheimer's Disease?
CALLI: I don’t have a personal connection to Alzheimer’s in particular, but I actually have a family member who has a different form of dementia.
NATE: Wow, Calli, I’m sorry. Thanks for sharing that. So, then as you know, it can be pretty serious. Alzheimer’s in particular is the leading cause of dementia in older adults, and affects 24 million people around the world, and at this moment there is a one in three chance of getting it in old age. And six million Americans live with the disease, and that’s expected to double by 2060.
CALLI: But it's been super hard to track down where exactly it comes from, right?
NATE: Okay, you do know something. Yes, that’s true, but a new theory is giving researchers hope in finally tracking down a source, and developing potential treatments and therapies. The new theory, the Lipid Invasion Model, suggests that Alzheimers develops after the blood brain barrier is damaged, and fatty substances called lipids build up in the brain causing brain damage.
CALLI: Oh fascinating. Okay, before we get too into that, can we define what exactly Alzheimer's Disease is?
NATE: Sure. So there are two types, the rarer, inherited, early-onset Alzheimer’s, and the more common non-inherited, late-onset Alzheimer’s that is associated with aging. This second type is becoming more common as we live longer. It's now the most common type of dementia. People show symptoms like memory loss, sleep disorders, and paranoia. For this one, scans show extensive brain cell death, neuro-fiber tangles, and the buildup of proteins.
CALLI: The protein buildup sounds familiar.
NATE: Yes! That’s been the leading theory. Excuse the jargon, but for a long time they’ve thought that type of dementia was caused by excess levels of the protein beta-amyloid. But this new theory focuses on lipids, and the blood brain barrier.
CALLI: We’ve been studying Alzheimer’s for a long time, is this theory a big shock to the field?
NATE: Well interestingly, when German physician Alois Alzheimer first described the disease in 1907, he noted the build up of lipids in the brain.
CALLI: Oh wow we’ve recognized it from the start?
NATE: Well that first physician saw it, but since then we’ve mostly focused on other sources. It turns out though, the source might be simple lipids.
CALLI: Right. The amyloid plaques are still there, but maybe not the cause of Alzheimers. Tell me more about the blood brain barrier. I’ve heard of it, but what exactly is it?
NATE: Right. So it's the system of blood vessels in the brain that controls what passes through to the brain. Now, it usually only allows a small number of essential substances, but the theory states that if it is damaged, other external substances may be able to make their way in.
CALLI: How would it get damaged?
NATE: Things like old age, head injury, hypertension, smoking, obesity, diabetes, chronic sleep deprivation, and stress, which are all actually known risk factors for Alzheimer’s already. The theory states that larger lipids might enter the brain through the damaged barrier. The brain can’t process these like it does other substances, and they could start building up in the brain. That buildup could lead to serious effects.
CALLI: Like what?
NATE: Brain shrinkage, plaques, neuro-fiber tangles.
CALLI: You’re describing symptoms of Alzheimer’s! So the blood brain barrier breaks down a bit, and regular old lipids accidentally make their way into the brain. That's all you need to start moving down the path to Alzheimer’s? If it's so pedestrian, are there things we can do to prevent it?
NATE: Well it is still just a theory. But researchers say it makes it clear how important it is to protect the blood brain barrier. And while there's not much we can do after the blood brain barrier is damaged to reverse its condition, we can limit these kinds of lipids to mitigate the effects.
CALLI: So we are on the way to finding a real cure? A prevention?
NATE: Researchers hope this theory gets us closer, but it certainly opens the door, a hopeful door, to new studies to find ways to prevent and treat Alzheimer’s.
CALLI: That's incredible. Hope in a sometimes hopeless field and looking to the past for future inspiration, pretty cool.
NATE: Definitely, sometimes all it takes to protect the brain, is a few brains.
[SFX: Whoosh]
NATE: Let’s recap what we learned today to wrap up.
CALLI: Carnivorous plants are survivors. When they couldn’t find nutrients in their soil, they looked to the sky. And while plants like this have independently evolved more than a dozen times, researchers have found striking similarities in how they went from soaking up the sun to sucking in flies.
NATE: Female athletes are experiencing more frequent, and more damaging brain injuries than their male counterparts. More and more studies are being dedicated to the issue to determine the cause and what can be done about it.
CALLI: Researchers have a new theory about the cause of Alzheimer’s. This new work suggests that a breakdown in our blood brain barrier may let lipids build up in our brain, and that causes the Alzheimer's symptoms. The new theory paves the way to potential prevention and treatment methods.