WEBVTT - Ep 33 Chytrid: The Silent Forest 0:00:00.360 --> 0:00:05.920 I've always loved frogs, toads, salamanders, all amphibians, and my 0:00:06.240 --> 0:00:08.840 mother also did, so she would bring us out. We 0:00:08.840 --> 0:00:11.240 didn't really have TV or anything along those lines. We 0:00:11.280 --> 0:00:14.280 spent our entire childhood running around in the woods, which 0:00:14.320 --> 0:00:17.680 is awesome. And she would take us out every spring 0:00:17.760 --> 0:00:20.919 to look at amphibian populations in this local state park 0:00:20.920 --> 0:00:23.480 called Haley Farm, and so we would go out, and 0:00:23.480 --> 0:00:25.120 we knew where to look for the eggs through all 0:00:25.120 --> 0:00:27.640 these little small ponds, and we would go out every 0:00:27.640 --> 0:00:31.240 week and we'd watch the eggs developed tabholes, and then 0:00:31.280 --> 0:00:34.640 those tabholes developed into metamorphs, the little baby frogs, and 0:00:34.640 --> 0:00:36.760 then those would grow up. And we did this my 0:00:37.000 --> 0:00:40.960 entire childhood. When I became a babysitter, that was the 0:00:41.000 --> 0:00:42.800 activity I took all the kids on. So we'd all 0:00:42.840 --> 0:00:46.040 go out and the Haley Farm and look for these amphibians. 0:00:46.520 --> 0:00:49.120 And then I taught special needs camps for years and 0:00:49.159 --> 0:00:50.760 we would do the same thing to bring the kids 0:00:50.760 --> 0:00:53.840 out and we'd look for the eggs. Now, as an adult, 0:00:53.880 --> 0:00:57.680 when I go back, the amphibians are not there. You'll 0:00:57.720 --> 0:01:02.560 see periodically adults, but we just don't see the babies. 0:01:02.600 --> 0:01:07.199 We don't see the eggs, and so they're probably they're 0:01:07.360 --> 0:01:10.080 they're just deeper in the pond or further out into 0:01:10.120 --> 0:01:12.800 the woods. But the populations are not what they used 0:01:12.800 --> 0:01:15.880 to be when I was younger. And it's really sad 0:01:15.920 --> 0:01:18.959 because there's something about going out into the environment and 0:01:19.040 --> 0:01:21.400 finding a frog in the woods that really fosters a 0:01:21.520 --> 0:01:24.600 love for that place like Hayley Farm is one of 0:01:24.600 --> 0:01:26.679 those really special places for me and I think for 0:01:26.720 --> 0:01:29.679 a lot of people. And now that we can't find 0:01:29.720 --> 0:01:32.720 the eggs, you know, kids aren't growing up in those 0:01:32.720 --> 0:01:35.760 state parks finding frogs. They're not finding the eggs, they're 0:01:35.760 --> 0:01:37.920 not trying to catch frogs, which is a huge part 0:01:37.920 --> 0:01:39.760 of my childhood growing up, and I think it is 0:01:39.840 --> 0:01:42.959 with a huge part of what made me become a 0:01:43.000 --> 0:01:48.000 concentration disease ecologists, because I loved that when I was younger, 0:01:48.800 --> 0:01:59.280 and it's just not a thing anymore for kids. 0:02:33.000 --> 0:02:37.079 Hi, I'm erin Welsh and I'm erin oman Updyke and. 0:02:37.120 --> 0:02:40.320 This is this podcast will Kill You Today. 0:02:40.360 --> 0:02:46.240 We're talking about Kittred Kittred, and you just heard a 0:02:46.280 --> 0:02:50.720 fabulous first hand account of some of the terrible effects 0:02:50.720 --> 0:02:55.000 that Kittred has had on Amphibian communities by our friend 0:02:55.000 --> 0:02:59.799 Tagan McMahon, Doctor Tagan McMahon. I should introduce her properly. 0:03:00.280 --> 0:03:02.359 And you will hear it more from her later in 0:03:02.400 --> 0:03:06.200 the episode, because she was so kind as to share 0:03:06.280 --> 0:03:09.799 some of her expert experience and knowledge on the subject, 0:03:09.919 --> 0:03:12.200 so we didn't have to do as much work. 0:03:12.520 --> 0:03:17.360 Yes, no, not kidding, though at least I didn't have to. 0:03:17.600 --> 0:03:21.960 Only kind of kidding. But before we get there, we 0:03:22.080 --> 0:03:27.480 have one very important thing to do, and that means. 0:03:27.320 --> 0:03:29.760 It's quarantine time time. 0:03:31.280 --> 0:03:32.920 What are we drinking this week? 0:03:33.200 --> 0:03:35.680 Today? We're drinking simply croaked. 0:03:38.920 --> 0:03:41.480 We shouldn't be laughing at this. It's not funny, but 0:03:41.520 --> 0:03:46.680 it's not funny punny, I'm tickled at the name. What's 0:03:46.680 --> 0:03:47.280 in croaked? 0:03:47.760 --> 0:03:52.800 There is mango puree, a bit of lime juice, some 0:03:53.000 --> 0:03:56.280 bubbly fizz water and rum of. 0:03:56.240 --> 0:04:00.880 Course delicious run a boil, oh if if you can 0:04:00.960 --> 0:04:01.400 grab it. 0:04:01.680 --> 0:04:06.920 And the key ingredient in this particular beverage is just 0:04:06.960 --> 0:04:08.720 a few sprinkles of chia. 0:04:08.480 --> 0:04:11.720 Seeds to look like frog eggs. 0:04:13.360 --> 0:04:16.920 You guys, I love it. We'll post the full recipe 0:04:16.920 --> 0:04:19.599 for this quarantini as well as our non Alcoholic Place 0:04:19.720 --> 0:04:22.960 Barta on our website and all of our social media channels, 0:04:22.960 --> 0:04:27.880 so you can find them there. Do you have any business. 0:04:27.520 --> 0:04:29.279 Erin I don't think so. 0:04:29.520 --> 0:04:33.280 We have merch. We have merch, go look at it. 0:04:33.760 --> 0:04:36.520 You can find our merch at our website. This podcast 0:04:36.520 --> 0:04:40.440 will kill you dot com by clicking on merch. And 0:04:40.480 --> 0:04:44.720 we've got t shirts and mugs and pins and the 0:04:44.720 --> 0:04:51.480 most important of all, soap. Soap we have It smells 0:04:51.560 --> 0:04:54.440 so good. I have a bar in my bathroom right now, 0:04:54.440 --> 0:04:56.320 and every time that I walk in there, I'm like, 0:04:56.360 --> 0:04:59.920 what smells so good? And it's the soap. Every single time. Legitimately, 0:05:00.240 --> 0:05:02.000 it makes the whole bathroom smell good. I didn't know 0:05:02.040 --> 0:05:02.719 soap could do that. 0:05:03.760 --> 0:05:05.040 Packaging is incredible. 0:05:05.160 --> 0:05:07.599 Okay, okay, so enough of that. 0:05:08.839 --> 0:05:13.839 All right, Kittredgy hit me with it. 0:05:14.200 --> 0:05:38.760 I'll hit you with it in just a minute, Okay, 0:05:39.560 --> 0:05:43.760 So listen, kittred First, off is a fungus. 0:05:44.839 --> 0:05:46.679 Our first fungus, Our first fungus. 0:05:46.720 --> 0:05:51.320 We like briefly talked about fung gui on the Biology 0:05:51.320 --> 0:05:54.480 of Superheroes podcast. Right, that's right. 0:05:54.520 --> 0:05:57.000 We talked about court. 0:05:56.839 --> 0:06:02.200 Aceps, cordyceps. Okay, but this is our first fora into 0:06:02.279 --> 0:06:07.560 the fun guy. Okay, so let's talk about this fungus 0:06:07.560 --> 0:06:12.400 itself first. The fungus that causes the disease known as 0:06:12.720 --> 0:06:23.480 kytridio micosis in amphibians is called batray coquittrium dendro but titus. 0:06:23.839 --> 0:06:26.280 I'm glad that you attempted that, because. 0:06:27.040 --> 0:06:30.560 I looked it up and I wrote out a phonetic 0:06:30.600 --> 0:06:32.560 spelling for myself. Yeah, I know. 0:06:32.800 --> 0:06:35.000 Can you can you quickly send that over to me 0:06:35.120 --> 0:06:36.280 because I need to do it. 0:06:36.279 --> 0:06:44.760 Later, Okay, battray coquittrium dendro bade titus, Okay, dendro get 0:06:44.800 --> 0:06:47.159 to it. You could call it b D. 0:06:48.839 --> 0:06:49.360 And I do. 0:06:49.839 --> 0:06:53.560 Okay, And I really hope that this isn't stepping on 0:06:53.600 --> 0:06:56.599 your history toes too much, Aaron. But I texted you 0:06:56.600 --> 0:07:00.679 about this because I got so excited and it blew 0:07:00.680 --> 0:07:04.880 my mind so much because we just did Giardia, which 0:07:04.920 --> 0:07:11.440 I said correctly, and we didn't Giardia I did, and 0:07:11.520 --> 0:07:15.520 it blew my mind in that episode that that parasite 0:07:15.560 --> 0:07:19.200 wasn't fully classified until like the late eighties. 0:07:19.720 --> 0:07:19.920 Right. 0:07:21.640 --> 0:07:27.360 B D wasn't described as a species until nineteen ninety nine. 0:07:28.120 --> 0:07:35.000 Yeah what? Yeah, Oh my gosh, I did not know 0:07:35.120 --> 0:07:35.960 that at all. 0:07:36.040 --> 0:07:40.800 It was thrilling information. Yeah, and there's another species that 0:07:40.880 --> 0:07:51.040 infects salamanders, battery Coquetrium salamandrivorians that was described in twenty thirteen. 0:07:51.840 --> 0:07:54.280 Uh huh, oh my god, this is the history is 0:07:54.320 --> 0:07:57.840 still being written. That's oh big time. Okay, So this 0:07:57.920 --> 0:08:01.800 is a fungus. We'll call it B D or probably 0:08:01.840 --> 0:08:03.640 a lot of times through this episode, we might just 0:08:03.720 --> 0:08:06.680 call it kittrid. But I do want to point out 0:08:06.720 --> 0:08:09.880 that there's a lot of other fungi in the group 0:08:10.040 --> 0:08:14.600 known as kittridio mycoda. So even though we'll be probably 0:08:14.680 --> 0:08:17.520 bad biologists and call it kittrid, I might slip up 0:08:17.560 --> 0:08:20.680 and call it kittrid. There are a number of different 0:08:20.760 --> 0:08:25.040 other kittrid fungi, many of which are free living and 0:08:25.160 --> 0:08:31.000 happily exist in the environment, digesting cellulose and kitan and keratin. 0:08:31.800 --> 0:08:36.360 Ding ding ding. That word's gonna come back. Other kittreds 0:08:36.440 --> 0:08:42.000 are parasitic on plants or algae or other invertebrates. But 0:08:43.000 --> 0:08:46.080 the one that we're focusing on today is the only 0:08:46.679 --> 0:08:49.560 I guess two species B D and B. Sal that 0:08:49.640 --> 0:08:58.520 are known to infect vertebrates, specifically amphibians. Okay, so today 0:08:58.520 --> 0:09:03.080 we're talking about an amphibian. Fur Fungi have very cool 0:09:03.120 --> 0:09:08.120 life cycles in general, and kitrid Kytridiomycota fungi are no exception. 0:09:09.520 --> 0:09:16.120 They have two life stages, the zospore and the zo sporangium. 0:09:17.640 --> 0:09:22.160 So the zospore is like a spore, so it travels 0:09:22.200 --> 0:09:25.200 through the environment, that's the point of it. And it 0:09:25.280 --> 0:09:29.800 happens to have an adorable little flagellum and it can swim. 0:09:31.200 --> 0:09:35.840 So the zospoor stage swims through water. It doesn't go 0:09:36.000 --> 0:09:38.680 very far, We're talking like a few centimeters, but it 0:09:38.720 --> 0:09:42.440 does swim, and it responds to chemotactic signals, so it 0:09:42.480 --> 0:09:46.960 actually can swim directionally towards a host, in this case, 0:09:47.040 --> 0:09:52.400 an amphibian. When it finds an amphibian, it releases a 0:09:52.440 --> 0:09:56.640 bunch of proteolytic enzymes. So it releases a bunch of 0:09:57.200 --> 0:10:02.119 stuff that digests the protein on the skin of the amphibian, 0:10:02.720 --> 0:10:05.640 and then it burrows its way into the skin of 0:10:05.679 --> 0:10:07.320 this let's call it frog. 0:10:08.040 --> 0:10:12.120 What cues is it using to find the host? 0:10:12.280 --> 0:10:14.680 That's a good question that I don't entirely know the 0:10:14.679 --> 0:10:18.080 answer to. It's a really good question, but they know that, Like, 0:10:18.480 --> 0:10:22.200 it's not just swimming at random. It swims directionally towards 0:10:22.280 --> 0:10:27.080 the frogs. But I'm not sure what about the frogs, Like, 0:10:27.080 --> 0:10:30.760 what are they releasing that they're swimming towards? Great question. 0:10:32.840 --> 0:10:35.240 So once it's at the frog, it burrows its way 0:10:35.280 --> 0:10:38.000 into the skin. It forms a little cyst, and then 0:10:38.040 --> 0:10:42.480 it forms the sessile or the non motile stage, the 0:10:42.600 --> 0:10:48.400 zosporangia underneath the skin of this little frog. That zosporangia 0:10:48.480 --> 0:10:52.400 will grow and then produce additional zo spores which will 0:10:52.440 --> 0:10:56.439 burst forth from the skin and swim along their way, 0:10:57.840 --> 0:11:01.400 and those zospores can either reinfect the same host in 0:11:01.480 --> 0:11:06.120 a new spot, or if they're close enough to another frog, 0:11:06.200 --> 0:11:10.560 they can infect a new host. Today, life cycle complete. 0:11:11.240 --> 0:11:13.800 And about how long is this all taking place? 0:11:14.240 --> 0:11:17.880 Oh gosh, Well, I know that the incubation period from 0:11:18.000 --> 0:11:21.920 when the zospor first infects to when the frog starts 0:11:21.920 --> 0:11:25.640 showing symptoms are between ten and eighteen days. Okay, So 0:11:25.679 --> 0:11:28.080 my guess is that that's about the timeframe that it 0:11:28.120 --> 0:11:29.920 takes for them to start shedding. 0:11:30.720 --> 0:11:33.679 And I would assume it it's variable depending on frog 0:11:33.720 --> 0:11:38.000 species and temperature, or amphibian species and temperature and et cetera, 0:11:38.040 --> 0:11:39.400 et cetera very variable. 0:11:40.200 --> 0:11:45.760 Yeah, okay, so let's talk about the symptoms of a 0:11:45.880 --> 0:11:48.040 kittrid kytritiomycosis infection. 0:11:49.160 --> 0:11:50.320 This is gonna make me sad. 0:11:50.640 --> 0:11:54.920 It's it's so sad. It hit me in the feels 0:11:55.679 --> 0:11:59.360 this one. So you can tell by the way that 0:11:59.400 --> 0:12:02.360 I describe the life cycle that this fungus it's pretty 0:12:02.400 --> 0:12:07.440 much just infecting the skin of these amphibians. So human 0:12:07.640 --> 0:12:11.960 listeners might be thinking something along the lines of how 0:12:12.000 --> 0:12:17.840 can a simple skin infection be so detrimental to an amphibian? 0:12:18.280 --> 0:12:22.000 It's just skin. Do you think anyone would say that, 0:12:22.200 --> 0:12:23.640 Maybe they would. 0:12:24.080 --> 0:12:24.520 I don't know. 0:12:26.120 --> 0:12:29.520 But for anyone who's not familiar with frogs and amphibians, 0:12:29.800 --> 0:12:33.480 their skin is not just a barrier between the frog 0:12:33.520 --> 0:12:36.480 and the outside world. It's not for us either, but 0:12:36.800 --> 0:12:40.240 in frogs it's an especially important organ. It's part of 0:12:40.280 --> 0:12:43.520 how frogs breathe, it's part of how they hydrate, how 0:12:43.520 --> 0:12:47.720 they thermoregulate, how they osmo regulate. So it's a very 0:12:47.800 --> 0:12:53.040 critical organ. Okay, So any kind of skin infection in 0:12:53.120 --> 0:12:55.560 a frog, you can assume is going to be bad 0:12:55.600 --> 0:12:59.679 news bears, and that is very true in kittrid. However, 0:12:59.720 --> 0:13:04.760 because B. D. Chytrid can infect so many different species 0:13:04.800 --> 0:13:08.600 of amphibians, the symptoms really do vary a lot based 0:13:08.640 --> 0:13:11.880 on the species and how serious the infection is varies 0:13:12.120 --> 0:13:16.040 hugely across species, and actually, Tagan, we'll talk a little 0:13:16.040 --> 0:13:19.439 bit more about that, because we don't fully understand why 0:13:19.559 --> 0:13:22.839 it is that some species seem to handle infection so 0:13:22.920 --> 0:13:26.800 much better than other species. But we can talk about 0:13:26.840 --> 0:13:28.880 some of the generalized symptoms that you see in a 0:13:28.960 --> 0:13:34.280 kytrideo micosis infection. First off, what's very interesting is that 0:13:34.400 --> 0:13:37.800 you don't see a lot of inflammation, so the frogs 0:13:37.880 --> 0:13:41.920 themselves aren't mounting a big inflammatory response when they get 0:13:41.960 --> 0:13:45.439 infected with this fungus. But what you do get is 0:13:45.480 --> 0:13:50.000 something called hyper keratosis, which means that you're making a 0:13:50.040 --> 0:13:52.840 whole bunch more keratin, which is kind of the protective 0:13:53.000 --> 0:13:56.480 protein that we have in our skin as well. It's 0:13:56.520 --> 0:14:01.839 the toughest, outermost layer of skin, which for a frog, 0:14:02.120 --> 0:14:06.120 because their skin has to be able to interact with 0:14:06.200 --> 0:14:09.679 the environment so much, this is especially bad because that 0:14:09.800 --> 0:14:14.920 means that this thick, extra extra keratinized layer is not 0:14:15.080 --> 0:14:18.760 going to be as permeable to water or air or electrolytes. 0:14:19.280 --> 0:14:20.480 That's really interesting. 0:14:20.840 --> 0:14:24.920 Yeah, I know that. Why didn't neither? Yeah, And then 0:14:25.360 --> 0:14:29.000 what you also get very very commonly is sluffing of 0:14:29.120 --> 0:14:32.080 the skin, So this skin will just start to slough 0:14:32.240 --> 0:14:38.200 off in sheets, which is really sad. You can get 0:14:38.400 --> 0:14:42.920 ulceration and like multiple cyst formation, but you don't always. 0:14:43.040 --> 0:14:46.720 The skin sloughing is kind of more common than this 0:14:47.200 --> 0:14:54.000 ulceration formation. Often also, the skin will become very discolored. 0:14:54.200 --> 0:14:57.320 So you might have seen classic photos of frogs infected 0:14:57.400 --> 0:15:00.600 with kittred that are bright red on their belly and 0:15:00.680 --> 0:15:04.520 their legs. So that's really common, is for their bellies 0:15:04.600 --> 0:15:08.880 to become disccolored, and it's also very in common. It's 0:15:09.000 --> 0:15:12.800 very common that they get infected at the highest rates 0:15:13.080 --> 0:15:16.320 or the most intense infection on their bellies and their legs, 0:15:16.360 --> 0:15:19.560 like the undersides, which to me kind of makes sense 0:15:19.640 --> 0:15:23.440 because this is a fungus that's in the environment and 0:15:23.920 --> 0:15:27.840 in the water specifically, so that's kind of the part 0:15:27.920 --> 0:15:30.320 of the frog that's probably in contact with water the 0:15:30.480 --> 0:15:33.000 most and in contact with the soil the most, right, 0:15:33.400 --> 0:15:37.840 But it can infect any part, any keratinized part of 0:15:38.520 --> 0:15:38.920 the frog. 0:15:40.280 --> 0:15:43.320 But does the infection tend to be localized in that 0:15:43.440 --> 0:15:46.440 way or is it pretty much systemic at a point? 0:15:46.800 --> 0:15:51.680 Well, that's an interesting question. So it's not systemic in 0:15:51.840 --> 0:15:55.360 that it doesn't travel throughout their body. This is a 0:15:55.560 --> 0:16:01.360 very localized skin infection. The zosporangia can produce like these 0:16:02.400 --> 0:16:04.480 I don't know if rhizomes is the proper word, but 0:16:04.560 --> 0:16:08.040 they can sort of spread out a bit where they infect, 0:16:08.680 --> 0:16:11.480 but really they also just produce a lot of spores 0:16:11.560 --> 0:16:14.560 that auto infect that same host on other parts of 0:16:14.640 --> 0:16:17.480 the skin. So you end up with really high burdens 0:16:17.520 --> 0:16:20.920 of infection where you have spores infecting all over the skin, 0:16:21.800 --> 0:16:26.200 but it doesn't travel like through their bloodstream, it doesn't 0:16:26.240 --> 0:16:30.120 invade their organs, et cetera. And that's I'm going to 0:16:30.160 --> 0:16:31.680 talk a little bit more about that in a minute, 0:16:31.680 --> 0:16:36.640 because it's a really interesting part of the story. Yeah. Yeah, 0:16:36.760 --> 0:16:39.440 So any and all parts of the skin can get infected. 0:16:39.560 --> 0:16:41.960 And then what you see happening in addition to all 0:16:42.000 --> 0:16:47.040 these skin changes is that the frogs become very lethargic. 0:16:48.480 --> 0:16:53.480 They stop seeking protection, they stop hiding during the day, 0:16:54.080 --> 0:16:56.400 so you can find them just sitting out and about. 0:16:57.200 --> 0:17:00.160 They're less responsive to stimuli. So if you try and 0:17:00.240 --> 0:17:02.560 get them to jump or to do something, they just 0:17:02.680 --> 0:17:08.000 kind of don't. They just don't really respond, and they 0:17:08.119 --> 0:17:11.360 can sit in a very kind of characteristic position where 0:17:11.400 --> 0:17:15.119 they're sitting out and their hind legs, their jumper legs 0:17:15.920 --> 0:17:19.119 are not poised underneath them like a frog ought to be, 0:17:19.280 --> 0:17:22.360 like ready to bounce at any second. They hang their 0:17:22.480 --> 0:17:25.120 kind of loose and gangly and they hold them away 0:17:25.119 --> 0:17:30.119 from their body. Isn't that sad? It's really sad, just 0:17:30.240 --> 0:17:33.160 this little loose like wop of a frog. 0:17:33.920 --> 0:17:41.080 Well just no like yeah, no willingness to yeh ever, yeah, ability. 0:17:40.960 --> 0:17:46.920 And then then they die. Yeah, sorry, there's no easy 0:17:46.960 --> 0:17:49.680 way to say that. So then they die. And what's 0:17:49.760 --> 0:17:56.000 interesting is that one very common cause of death is 0:17:56.160 --> 0:18:03.119 actually heart attack, ty, any little froggy heart attack? 0:18:04.080 --> 0:18:06.240 Is this because they can't regulate water? 0:18:06.560 --> 0:18:08.520 Oh look at you airon you're so smart? 0:18:10.880 --> 0:18:11.120 Yeah. 0:18:11.280 --> 0:18:14.480 So again, this is an infection that's not actually invading 0:18:14.600 --> 0:18:18.440 any organs in general. It can in some cases, but 0:18:18.800 --> 0:18:22.600 in general it's just in the outermost layer of this 0:18:22.760 --> 0:18:27.640 frog's skin. And so we don't fully understand exactly how 0:18:28.560 --> 0:18:31.760 this disease ends up killing frogs. But what it does 0:18:31.920 --> 0:18:35.440 seem to do, according to a twenty eighteen paper that 0:18:35.560 --> 0:18:40.600 I found, is that it causes widespread metabolic imbalance. So 0:18:41.480 --> 0:18:44.520 the electrolytes of the frogs get completely messed up because 0:18:44.520 --> 0:18:48.159 they're not able to osmo regulate through their skin like 0:18:48.200 --> 0:18:51.719 they're supposed to. They can't regulate the water and electrolytes 0:18:51.760 --> 0:18:55.240 moving in and out of their skin. And when that happens, 0:18:55.720 --> 0:18:58.920 other organs can get messed up. So then other important 0:18:59.040 --> 0:19:02.440 metabolites that you're body would normally produce, like say your 0:19:02.520 --> 0:19:07.359 liver would normally produce these certain metabolites that liver the 0:19:07.440 --> 0:19:11.520 liver can't do that because the other electrolytes are so 0:19:11.680 --> 0:19:16.640 messed up. Does that make sense? So while kittred itself 0:19:16.840 --> 0:19:21.560 doesn't invade frog's livers or hearts, the osmodic deregulation that 0:19:21.680 --> 0:19:24.760 it causes just by infecting the skin to such a 0:19:24.840 --> 0:19:29.320 degree ends up affecting processes in their internal organs and 0:19:29.520 --> 0:19:31.320 that's what ends up causing death. 0:19:32.400 --> 0:19:35.520 That makes sense and horrible sad sense, Yeah. 0:19:35.359 --> 0:19:38.399 Horrible and sad, And it's it was really interesting to 0:19:38.720 --> 0:19:42.119 sort of do the research on this because it's so recent. 0:19:43.240 --> 0:19:45.560 Because a lot of times when I'm trying to figure out, 0:19:45.800 --> 0:19:48.440 you know, what's the path of physiology of a disease, 0:19:49.480 --> 0:19:52.800 I just I find a paper that's relatively recent, like 0:19:52.880 --> 0:19:56.240 the last twenty years, and they've got pretty much an answer. 0:19:56.359 --> 0:19:58.600 But in this one, if you go back just five 0:19:58.720 --> 0:20:01.920 or ten years, it's all, here's our hypothesis, here's the 0:20:02.000 --> 0:20:04.640 best guess we have. And so it's only from these 0:20:04.680 --> 0:20:07.880 really really recent papers, like this twenty eighteen paper, which 0:20:08.000 --> 0:20:11.240 I will post on our website, where they actually found 0:20:11.480 --> 0:20:13.880 sort of evidence of this. It's still not entirely clear 0:20:14.080 --> 0:20:17.960 how this happens, but there is good evidence for this 0:20:18.119 --> 0:20:19.720 widespread electrolyte imbalance. 0:20:20.680 --> 0:20:23.840 I would bet that that's also just also a factor 0:20:23.920 --> 0:20:26.679 of it being a wildlife disease versus a human disease. 0:20:26.920 --> 0:20:31.760 Definitely definitely funding research, etc. Right, And another thing I 0:20:31.880 --> 0:20:35.200 noticed is that so much of what we study in 0:20:35.520 --> 0:20:39.359 wildlife diseases compared to human diseases is all population level 0:20:39.520 --> 0:20:42.920 rather than individual level. So like the disease process that's 0:20:42.960 --> 0:20:46.200 happening inside each individual frog is not studied to the 0:20:46.240 --> 0:20:49.320 same extent as a disease in humans might be. If 0:20:49.359 --> 0:20:49.880 that makes sense. 0:20:50.359 --> 0:20:52.840 We don't have we lack the case studies in wildlife, Yeah, 0:20:53.040 --> 0:20:54.119 exactly these cases. 0:20:54.200 --> 0:20:58.879 Yeah, yeah, So that's pretty much the biology. The other 0:20:58.960 --> 0:21:00.760 thing I did want to say that I think is 0:21:00.920 --> 0:21:07.720 interesting is that so BD kittred amphibian Kittrid only infects 0:21:08.320 --> 0:21:14.760 keratinized epithelium, so that means that actually tadpoles aren't infected, 0:21:15.520 --> 0:21:19.440 So tadpoles actually can survive in areas that have BD. 0:21:20.200 --> 0:21:23.159 The only part of a tadpole that has keratin is 0:21:23.240 --> 0:21:25.320 the mouth parts, so that's the only part that b 0:21:25.440 --> 0:21:28.680 D can potentially infect. But then as soon as a 0:21:28.720 --> 0:21:33.280 tadpole starts to undergo metamorphosis, as soon as they start 0:21:33.359 --> 0:21:37.639 to change into adults, then they've got that keratin, then 0:21:37.680 --> 0:21:41.399 they can be infected, so even really early early frogs, 0:21:41.440 --> 0:21:43.280 but just not tadpoles specifically. 0:21:44.080 --> 0:21:44.199 Right. 0:21:44.720 --> 0:21:48.040 But what's also very interesting is that a lot of 0:21:48.240 --> 0:21:53.680 free living Kittrid fungus also feeds on keratin, and so 0:21:53.800 --> 0:21:57.600 it's hypothesized that that's exactly what this fungus is feeding 0:21:57.680 --> 0:22:01.480 on in the frogs, and it's interesting that it's causing 0:22:01.560 --> 0:22:06.119 this hyperkeratotic response where the frogs they're not mounting an 0:22:06.119 --> 0:22:09.439 immune response, they're not coming in and fighting off this infection, 0:22:09.600 --> 0:22:13.360 but rather they're making more and more keratin, and that's 0:22:13.520 --> 0:22:16.800 potentially what this fungus is feeding on. So it's like 0:22:16.880 --> 0:22:20.119 the fungus is creating the optimum environment for itself to 0:22:20.240 --> 0:22:21.720 survive in this frog. 0:22:22.200 --> 0:22:26.560 Right, I mean, it's it's ingenious. Yeah, and huh, I 0:22:26.720 --> 0:22:30.880 know where what else is keratin? Tell me more about keratin. 0:22:31.119 --> 0:22:34.160 So, keratin is the protein. It's all of our skin, 0:22:34.600 --> 0:22:37.719 Like any skin that you see, it's all keratinized. Your 0:22:37.800 --> 0:22:41.120 hair is keratin, your nails are keratin. It's a protein 0:22:41.320 --> 0:22:44.600 that makes it's like a very tough outer protein. So 0:22:44.920 --> 0:22:48.399 our skin as it grows and moves, like from the 0:22:48.440 --> 0:22:52.040 basal layers and then it moves up, it becomes keratinized. 0:22:52.080 --> 0:22:54.720 So by the time that it reaches our outside environment, 0:22:54.800 --> 0:22:57.840 it's like completely just mostly keratin. There's not really any 0:22:57.920 --> 0:22:58.520 cell left. 0:22:59.200 --> 0:23:02.800 So why amphibians and not other animals. 0:23:02.560 --> 0:23:06.720 Great question, it's a really good question. I'm sure that 0:23:06.800 --> 0:23:09.040 it's not the exact same keratin. There's a lot of 0:23:09.080 --> 0:23:11.879 different types of keratin, so it might just be that 0:23:12.000 --> 0:23:17.320 they can infest a very specific form of keratin. That's 0:23:17.359 --> 0:23:18.400 a really good question though. 0:23:19.080 --> 0:23:20.800 H Yeah, interesting. 0:23:21.200 --> 0:23:23.960 Yeah, so that's the biology. 0:23:24.520 --> 0:23:27.680 Oh that was it? What do you think? That was great? 0:23:28.119 --> 0:23:31.040 It was so fun to learn about. I knew nothing 0:23:31.119 --> 0:23:33.760 about Kittrid. Oh yeah, no, I. 0:23:33.800 --> 0:23:38.280 Knew nothing except sort of like the broad sweeps. 0:23:37.920 --> 0:23:40.920 Of it, right, Like I knew it's real bad for 0:23:41.119 --> 0:23:44.560 frogs and it's causing widespread havoc and that's literally and 0:23:44.720 --> 0:23:47.879 like I've seen pictures of ponds where Kittrid is just 0:23:48.160 --> 0:23:50.680 you know, all these dead frogs. That's all that I knew. 0:23:51.240 --> 0:23:51.440 Yeah. 0:23:51.520 --> 0:23:55.760 So, oh so, Aaron, tell me, how did we get here? 0:23:57.040 --> 0:23:58.280 What's the history of this thing? 0:23:58.760 --> 0:24:00.240 Okay, I'll see what I can do. 0:24:01.119 --> 0:24:02.679 Right after this break. 0:24:30.880 --> 0:24:34.840 In the nineteen eighties, all over the world, the forest 0:24:35.080 --> 0:24:39.960 started to go silent. Oh no, it started to become static. 0:24:40.440 --> 0:24:40.720 Still. 0:24:41.840 --> 0:24:44.479 This was not the vibrant, dynamic forest that we were 0:24:44.600 --> 0:24:49.320 used to. Something many somethings were missing, and it didn't 0:24:49.359 --> 0:24:54.800 go unnoticed. Herpetologists across different continents began talking amongst themselves. 0:24:55.720 --> 0:25:00.000 Where have the frogs gone? Where have the salamanders gone? 0:25:00.280 --> 0:25:03.840 Where have the toads gone? Where there used to be 0:25:04.359 --> 0:25:09.640 untold numbers of frogs, toads, salamanders, amphibians, Now there were none. 0:25:10.080 --> 0:25:14.760 Even stranger were the circumstances of this sudden disappearance. Amphibians 0:25:14.760 --> 0:25:17.760 were going missing in habitats of all kinds, from urban 0:25:17.920 --> 0:25:22.760 streams to remote, highly protected conservation regions, and often there 0:25:22.800 --> 0:25:26.320 were no bodies to be found. What Yeah, they just 0:25:26.400 --> 0:25:31.640 sort of disappeared, which makes sense, okay. In other places, 0:25:32.680 --> 0:25:36.800 the sad carcasses of amphibians piled up, which was in 0:25:36.920 --> 0:25:41.600 itself maybe even more bizarre because in places like the tropics, 0:25:41.720 --> 0:25:44.760 something as small as a frog can be quickly dismantled 0:25:44.800 --> 0:25:47.920 by ants or dispatched by a bird within a matter 0:25:48.040 --> 0:25:52.240 of minutes or hours, So the sight of these corpses 0:25:52.520 --> 0:25:57.640 was maybe even more worrying than their absence. What could 0:25:57.720 --> 0:26:04.359 be causing such widespread devastation, Climate change, habitat destruction, environmental toxins, 0:26:04.400 --> 0:26:08.920 and infectious diseases were all the immediate culprits. Finding out 0:26:09.040 --> 0:26:12.720 what was causing these amphibian die offs was top priority 0:26:12.760 --> 0:26:14.879 if there was any hope of saving even some of 0:26:14.960 --> 0:26:21.440 the species. Extinction happens, but not often like this. This 0:26:21.720 --> 0:26:26.000 is probably the largest extinction event that modern humans have 0:26:26.240 --> 0:26:30.800 been witnessed to so far. Wow, maybe this is pessimistic 0:26:30.880 --> 0:26:33.640 of me. But I don't think it'll be the last 0:26:33.720 --> 0:26:35.200 one we see in our lifetime. 0:26:36.760 --> 0:26:37.479 You're probably right. 0:26:38.080 --> 0:26:43.680 Yeah, let's talk about amphibians. Okay, what does the word 0:26:43.800 --> 0:26:44.720 amphibian mean? 0:26:45.520 --> 0:26:48.440 Oh, good question. Tell me. 0:26:48.960 --> 0:26:52.120