Welcome to STEMology – Show Notes

Season 1, Episode 19

Satelites saving the Earth, germinating seeds, fractal genes, addicted fish

In today’s episode of STEMology…

David and Sophie are talking about saving the earth by shooting asteroids with satellites, scientists’ discovery on protein in a plant giving signal for the seed to grow even after a thousand of years being dormant, what causes the fractal structure in a plant and how a fish can be addicted to meth…

Saving Earth

So this is the point we’re at in our society where we’re now literally playing the game asteroids…

Germinating Seeds

Basically this protein FLOE 1 seems to behave in this way. It aggregates when the cell gets wet. And then if the cell gets wet enough, then it says it sends a go or no go signal, but presumably it’s a grow or no growth signals

Fractual Genes

So what they did is they basically manipulated the genes of A Thaliana in both computer simulations and growing experiments in the lab. And they’re essentially able to sort of like grow these fractal cauliflower heads on  A Thaliana

Addicted Fish

They make another really good point that if  the fish are chasing a drug reward that may overshadow natural rewards, like foraging or mating, that the fish needs to be doing it in order to like, look after themselves as a species. And that’s bad…

This is a “kind of, sort of, vaguely close” copy of the words that David & Sophie speak in this episode.

IT IS NOT 100% accurate.  We are very sorry if we have spelt something completely incorrectly.  If it means a lot to you to have it corrected, email us at stemology@ramaley.media


STEMology s1e19


[00:00:00] [00:00:00] Sophie: [00:00:00] Welcome to episode 19 of STEMology

[00:00:03]David: [00:00:03] a podcast sharing some of the interesting fun, and sometimes just patently bizarre news in science, technology, engineering, or maths.

[00:00:10]Sophie: [00:00:10] Your hosts are Dr. David Farmer and Dr. Sophie Calabretto

[00:00:14]David: [00:00:14] This week, we are speaking about literally saving the earth, germinating seeds,

[00:00:19]Sophie: [00:00:19] fractal genes, and meth-y meth-y fish.

Saving Earth

[00:00:22] David: [00:00:22] So our first story Sophie is about literally saving the earth. So we’re, we’re literally saving the earth from giant rocks.

[00:00:32]Sophie: [00:00:32] Yeah. Like in the movies, right. There’s like an asteroid and it’s hurtling towards the earth and we’re all going to die unless we can intercept it.

[00:00:39] David: [00:00:39] Yeah. And in those movies like Armageddon, we can only stop the asteroids by sending people there, playing Aerosmith and the capsule the entire time. Whereas this is proposing something different. This is a study done by Airbus and funded by the European Space Agency, suggesting that we use telecom [00:01:00] satellites and batter them off the asteroid to change its path.

[00:01:03]Sophie: [00:01:03] Yeah, I really liked this. And so the idea was the Airbus Defense and Space and they run out of Europe and they presented their results at the Planetary Defense Conference, 2021, which makes me joyous. And I know it makes you joyous too.

[00:01:16]David: [00:01:16] It does. It’s one of those job titles, planetary defender, like weapons experts that you just really can’t or spy that just can’t get much cooler than

[00:01:24] Sophie: [00:01:24] Yeah. I know I made some bad life choices like mathematician. Yeah. so they came up with some scenarios. So the idea is that we’re assuming the discovery of an asteroid with a very short warning time and in asteroid time, that’s one to three years. So we have an extremely constrained mission preparation time.

[00:01:42] And also we have a to launch requirement of six months or less, right? So this result. In a build or system adaptation timeframe of two to three months. So this is what they’re talking about. And they came up with three options, Dave. So the first option as you said, we’re going to be hurtling things at the [00:02:00] asteroid. So I should very quickly that this is part of a mission concept called the fast kinetic deflection or fast K D mission concept. Yeah. And so the idea is essentially we’re hurtling giant things at the asteroid to sort of knock it a little bit off course and hope that it will avoid the earth. Yeah. so the first of the option is just building dedicated spacecraft, which I love.

[00:02:21] It’s like you go to a bunker somewhere and you just fill it with like big, heavy spacecraft and they just hang out there until never doubly an asteroid, starts hurtling at the earth and we need to save ourselves. So that’s option one.

[00:02:32] David: [00:02:32] Yeah.

[00:02:33] Sophie: [00:02:33] Option two, which is the winning option. Spoiler, is the hijacking scenario, which I think is great.

[00:02:39] So hijacking scenarios, basically, we take all these like telecom, satellite manufacturers around the world, and we say, “yo, I know that you’re building these for telecommunication and TV and that kind of stuff, but what I’m going to need you to do right now is turn that into an anti asteroid weapon.”

[00:02:55] All right. And then we launch those. And then the last one was what they called a cherry picking [00:03:00] scenario, which I didn’t quite get. And they refer to it as the emergency reallocation of any suitable platform, hardware units from any European integration facilities followed by fast process to build kinetic impact spacecraft.

[00:03:12]anyway, but the hijacking Dave

[00:03:14] David: [00:03:14] Yeah. And they’re making what they call a kinetic impact or system, which is literally where you just take rockets for telecom satellites and battered them off the asteroid. And I really loved some of the language in the report. So it says, “with the information of a credible asteroid impact threat political decision-makers are expected to push for rapid deflection attempt using kinetic impact or technology,”

[00:03:36] a credible asteroid impact threat. Like who’s phoning  in non-credible asteroid impact threat. It’s like, oh, is the asteroid impact threat credible? No it’s just Steve from administration called it in Like, anyone can make a bomb and phone in a bomb, but who can phone in an asteroid? This is ridiculous.

[00:03:54]Sophie: [00:03:54] I agree, Dave, it is ridiculous, but Yeah, so I thought there’s one drawback at [00:04:00] this stage. So the idea is even if we took their satellites, they’ll need to be fitted with special modules, enabling for sort of communication and deep space and navigation and guidance and all those things that a telecommunication satellite, which is designed to be hanging out in a geostationary orbit, all those things it needs to actually launch itself as an asteroid. but they haven’t developed these modules yet. So ideally we would need to build these first and then probably test them in advance and then just have them sort of ready in case of emergency.

[00:04:29]David: [00:04:29] Yeah, just ready saying ready to go. And this is important. So, Albert Folk who was head of the report, said, humankind should want to be prepared if a 1000 foot or 300 meter asteroid, such as that envisaged by our study hit somewhere in central Europe. It would cause widespread destruction across the whole continent.

[00:04:46]but apparently the reports and he were a bit furtive about what would happen if the asteroid was bigger than that. And which is something we also need to be worried about because apparently the asteroid that led to the extinction of the dinosaurs was 9.6 kilometers in [00:05:00] diameter, which is a whole order of magnitude bigger.

[00:05:02]Sophie: [00:05:02] the idea is we’re going to take 10 telecom satellites, so I’ve got a few facts just about those really quickly, Dave, cause we need to know how big they are. So apparently it just described like a small bus, so they can be between around 3,600 – 5, 400 kilograms. And if we had 10 of those and we launched them in quick succession, and they all hit where they should hit, that would be enough for us to sort of knock this thing off. of course, but we’re talking about an asteroid that is about 300 meters in diameter. And as you said, the one that killed the dinosaurs is at 9.6, which is a little bit of an issue, but you know that they’ve got the world’s first asteroid deflection experiment set to take place next year.

[00:05:41]David: [00:05:41] that’s so cool.

[00:05:42]Sophie: [00:05:42] NASA’s mission called DART, which stands for Double Asteroid Redirection Test is expected to ram into a small asteroid moon called Dimorphos, which orbits a larger asteroid code. And it’s a great word. So I’m going to say Didymos because I don’t think it’s Diddy Moss. I’m going to say to Didymos, so.

[00:06:00] [00:05:59] David: [00:05:59] Sounds more Greek and kind of impressive.

[00:06:02]Sophie: [00:06:02] Yeah, so dimorphos is around 160 meters across. So again, this is even smaller than the 300 metre asteroid in this scenario.

[00:06:10] David: [00:06:10] Wait. Okay. So This is the point we’re at in our society where we’re now literally playing the game asteroids.

[00:06:16] Sophie: [00:06:16] We’re playing the game. Asteroids.

[00:06:18] David: [00:06:18] IRL.

[00:06:19] Sophie: [00:06:19] IRL, but let me tell you why this makes me a little bit sad. So the, idea is to bring Dimorphos and Didymos closer to each other. So Dimorphos’ orbit is shortened by about 10 to 20 minutes. They’re going to use a 600 kilos spacecraft to launch this thing, but the name Dimorphos

[00:06:35] from the Greek literally means having two forms and they named it based on what they’re going to do to it. So when I first read it, I was like, hold on, it’s an asteroid. And then you’re going to like, shoot something at it and exploded. And now it’s dead. And you actually named after that, but they’re actually just going to knock it off course, but they literally, named it after the thing that they’re going to do.

[00:06:53] And that is like change the form of the orbit.

[00:06:55] David: [00:06:55] Yes. We’ve discovered a new asteroid. We’ve called it pew, pew, pew. [00:07:00] And we’re going to shoot the hell out of it.

[00:07:02] Sophie: [00:07:02] Yeah, exactly. so that’s cool. So that’s apparently happening next year. Actually. I think it’s been COVID delayed, but apparently still, maybe next year they’re going to be shooting some 600 kilogram spacecraft at a Dimorphos to see if they can shorten its orbit.

[00:07:16] David: [00:07:16] So this is all, some really good news. I think we’re making excellent progress as a species. And I think all of the things we’ve said justify something else that Albert Folk said, which was that human kind seems to be in a better position than the dinosaurs, which is true because well, a we can shoot asteroids out of the sky maybe, and also, well, we’re not all dead.

[00:07:36] Sophie: [00:07:36] Yeah, that’s true.

Germinating Seeds

[00:07:37]  From dinosaurs in space to germinating seeds. That’s not what we were talking about, Dave.

[00:07:53] David: [00:07:53] So this is some work of Carnegie and Stanford Universities looking at the way seeds tell when [00:08:00] it’s the right time to germinate. So basically a seed is a little protective capsule that protects plant embryos and can protect them for a long time. Can protect them for a millennia if necessary.

[00:08:11] Sophie: [00:08:11] which is crazy. I didn’t realize that a seed could lay dormant for like thousands of years.

[00:08:16] David: [00:08:16] Yeah. so basically, when it gets exposed to water, that’s when they tend to germinate, but that’s also last chance to bloom. So once the seeds started to germinate, it can’t go back to the state it was in before. So deciding when to germinate is really important. And these researchers reckon they figured out how the plant cells do that.

[00:08:33] Sophie: [00:08:33] Yeah. So we never knew that before. Right? So like when we know that these things can lay dormant, we know that, you know, once they start germinating that’s it, but we didn’t actually know how that sort of baby plant in its shell reactivates the cellular activity that it needs to germinate until now.

[00:08:49]David: [00:08:49] Until now. So they’ve discovered what they call up is a prion like protein called FLOE 1, which is crucial to the plant’s ability to walk the tightrope between too [00:09:00] soon and too late with regards to deciding to germinate. and there’s something really, really interesting about this. So this protein seems to operate on a principle called phase separation and to explain phase separation, I need to kind of explain cells a little bit in general.

[00:09:15] So basically. In a cell,  you’ve got these things called organelles, which are kind of like your organs in the way that you have a kidney to do kidney stuff and a heart to do

[00:09:23]Sophie: [00:09:23] a clever name then now I understand.

[00:09:26] David: [00:09:26] Yeah. So cells have organelles, which are the same thing. They’re kind of specialized little compartments. So the nucleus contains the DNA and the golgi apparatus makes proteins

[00:09:34] Sophie: [00:09:34] Oh, okay. So the old those things are called organelles

[00:09:37] David: [00:09:37] Yeah, they’re called organelles. So each one of those is an organelle and they all have their own little specialized job. Now, typically the way that those get organized is they have walls, right? They have literally walls of fat that contain all the proteins that are necessary to perform those jobs.

[00:09:53] Sophie: [00:09:53] just like my heart and my liver aren’t joined together.

[00:09:56]David: [00:09:56] Exactly. So typically what happens is when you look down a [00:10:00] microscope, you can see these structures because they have walls and you can see, oh, there’s an organelle, And then you go and study those things cause you could see them. Phase separation is completely different.

[00:10:08] Phase separation is basically a group of proteins coming together, just floating around in the cell, but coming together to perform a job and then dispersing again.

[00:10:19] Sophie: [00:10:19] Wait, wait, Dave. it’s like when the power ranges form Megazord..

[00:10:23] David: [00:10:23] Yeah, basically they formed Megazord and then they kill the man or women in the rubber suit, and then they

[00:10:31] Sophie: [00:10:31] and then they do, and then they disperse and then they become their own individual Power Rangers  again.

[00:10:34] David: [00:10:34] Exactly. Exactly. So that’s obviously that’s a newer idea and that’s probably a newer idea because yeah, when you look down a microscope, you can see cell walls and you can organelle walls and say, I want to study that, but this is harder to see because you can’t see it. When you just look down a microscope, you have to kind of know what to look for and then find it.

[00:10:52] So basically this protein FLOE 1 seems to behave in this way. It aggregates when the cell gets wet. And then if the cell gets wet [00:11:00] enough, then it says it sends a go or no go signal, but presumably it’s a grow or no growth signals.

[00:11:06] Sophie: [00:11:06] Oh yeah. And that’s true because they do say no or no, go a lot, but you’re right. It’s a grow or no grow.

[00:11:12] David: [00:11:12] That would seem to be more on brand.

[00:11:14] Sophie: [00:11:14] Maybe they had a character count in their paper. Like,

[00:11:16] David: [00:11:16] Maybe they did. They probably did. Cause I think this was published in Cell.

[00:11:20]Sophie: [00:11:20] Okay.

[00:11:21] David: [00:11:21] And so basically that’s how FLOE 1 works when the cell gets wet, it aggregates. And then when it aggregates to the extent that the cell is wet enough, it sends a signal to the cell saying, yeah, go let’s become a plant now.

[00:11:32]Sophie: [00:11:32] That’s cool. So apparently they conducted this work using the Arabidopsis Thaliana but they found that FLOE 1 is present throughout the plant kingdom and then Dave, I think you’ve really nicely explained phase separation. Cause when I look at phase separation, I think of it in a fluid terms and it’s completely different. So I didn’t know what was going on. So I went, I’m going to go and find out about A Thaliana and Dave, do you know that there’s A Thaliana living on the moon right now?

[00:11:57] David: [00:11:57] No. Wait, what’s A Thaliana.

[00:11:59]Sophie: [00:11:59] sorry, is the, [00:12:00] Arabidopsis the thale crests or mouth ear cress, is the common name for it and apparently on January 2nd, 2019, China’s Chang’e 4 lander brought A Thaliana to the moon. So they had a small microcosm tin in the Lander and it contained A Thaliana, seeds of potatoes and silkworm eggs. And the idea is that plants would support the silkworms with oxygen and the silkworms would in turn provide the plants with necessary carbon dioxide and nutrients who they waste. And researchers will evaluate whether the plant successfully perform photosynthesis and grow and bloom in lunar environments. So I just thought that was fun.

[00:12:37]David: [00:12:37] that’s so cool.

[00:12:38]Sophie: [00:12:38] A Thaliana teaching us about germination and hanging out on the moon.

Fractal Genes

[00:12:42]  So Dave,  the genes responsible for the fractal head of a romanesco cauliflower [00:13:00] have been identified.

[00:13:02] David: [00:13:02] Have you ever eaten a romanesco cauliflower

[00:13:04] Sophie: [00:13:04] I have once.

[00:13:05]David: [00:13:05] you have once? It was a memorable experience?

[00:13:08]Sophie: [00:13:08] because I am a big fan of cauliflower and broccoli and a lot of those other like fun dudes from the cabbage family, the romanesco just had a slightly weirder texture that I didn’t love. And that’s why I remember it.

[00:13:20] David: [00:13:20] Oh, so it was not an enjoyable, memorable experience.

[00:13:23] Sophie: [00:13:23] No, it was very similar, but because it’s kind of like, if you don’t, know what a romanesco cauliflower looks like. It’s kind of like a normal cauliflower, but it’s made into, it looks like a micro fractal version. So they’re kind of the curd, this is what I learned this week. The bit of the cauliflower that we eat is called the curd. And that’s because it looks like cheese curd.

[00:13:40]David: [00:13:40] Oh, that’s very apt.

[00:13:42] Sophie: [00:13:42] Yeah. Anyway. and So what they did is they got, funnily enough, Dave, this same plant Arabidopsis Thaliana

[00:13:49]David: [00:13:49] Arabidopsis is like a darling of the genetic world. It’s like the plant that geneticists study, because it’s really well characterized. And I think has maybe got quite a relatively simple genome maybe.

[00:13:58]Sophie: [00:13:58] Yeah. I think that’s what [00:14:00] Wikipedia sort of suggested to me when I looked it up. so it’s funny. So if you look at this plant so you can Google it and basically it doesn’t at all look like a cauliflower or a fractal. So basically you’ve got leaves forming a Rozette at the base of the plant, and there are a few leaves on the flowering stem. It looks like a plant, but what they managed to do is, do we need to get into fractals Dave?

[00:14:19] David: [00:14:19] We should briefly explain what a fractal is maybe.

[00:14:22] Sophie: [00:14:22] Yeah. Let’s briefly explain what fractal is. So basically it’s just a never-ending pattern, but the idea is it’s a self-similar pattern across different scales. So like the famous one in maths is the Mandelbrot set, which is named after our mate. Dr Almond bread, I found that out once that almond is Mandel in German and brot is bread.

[00:14:40]David: [00:14:40] And he had a fractal name. Uh Coastlines aren’t coastlines a fractals, because the more that you zoom into them, the more they just appear to be the same

[00:14:48] Sophie: [00:14:48] Yes. So that, and that’s the whole idea. So if you think about like, so frost, crystals, and snowflakes, you’ve got various flowers, you’ve got cauliflowers, which we’re going to talk about in a second, even lightning or things in the cardiovascular system. So think of [00:15:00] anything that branches like, if you think of a tree, you go to trunk and from the trunk you got these big. branches growing off. And then if you look at the big brunch, is there a little branches has growing off those? And if you look at those little branches, they’re a little more, you know, to the point that I guess you’re getting to tweaks, but it’s that idea of this kind of self-similar patent that goes on forever. Although like not always forever in the case of a tree, because you know,

[00:15:21]David: [00:15:21] and It’s not just like phenomenology. It can be really important. Like you mentioned the cardiovascular system and the self-similar properties of the cardiovascular system. Really important for its efficiency. So without these properties, we would either be dead or we’d be really small.

[00:15:33]Sophie: [00:15:33] which I guess, I mean, I’d rather be really small than dead so the idea is they took,A Thaliana they know that there’s a variant that can produce smoke, cauliflower- like structures, and that’s due to a double mutation in apathela 1or AP one, and then cauliflower CAL genes, which are related to floral development.

[00:15:51] So what they did is they basically manipulated the genes of A Thaliana in both computer simulations and growing experiments in the lab. And they’re essentially able to sort of like grow these fractal cauliflower heads on Thaliana.

[00:16:05] David: [00:16:05] Yeah. So they, with the color flare, this is my understanding. It’s a very intense genetic paper and I found it quite difficult.

[00:16:11] Sophie: [00:16:11] I tried to look up, I’ll tell you in a bit about, I looked at the computer simulations and the models, and I think my brain melted, like it just liquified in like small parts of the brain. It’s juicy in there now.

[00:16:23] David: [00:16:23] Yeah. So basically on the romanesco cauliflower, the reason you end up with a fractal pattern is that you have these stems that start to flower, and then they decide not to flower for some genetic unknown reason. And then they turn back into stem and the pattern that, that produces by happening repeatedly gives rise to this fractal pattern in the cauliflower. So when I’ve said things like it turns into stem and then starts to flower, and then doesn’t flower on a genetic level. That means that particular genes are being switched on and off at every stage of that process. So if the plant has these particular genes and they’re expressed in a particular way at particular [00:17:00] time, that’s what gives rise to the pattern.

[00:17:01]And yeah, so they did a computer model. Showing that growing in this way. Well, my understanding was growing in this way, but produce a fractal pattern on a different plant. And then they actually knocked the genes into the rabid DOCSIS and show that they can produce these romanesco cauliflower- like patterns on the Arabidopsis

[00:17:19] Sophie: [00:17:19] Yeah. So they did in terms of the model, Dave, no, i’m not going to go into in great detail because I have no idea what was happening inside of it. So they have what they call a GRN model, which is a Gene Regulatory Network, which is like a common thing from what I can tell when you do gene stuff and this was a floral gene regulatory model, which are basically modeled for types of organs that shaped the aboveground architecture of the plant, the Mary stems, the internodes, the leaves and the flower. So the Mary stems are probably I don’t know like the happiest of the stems

[00:17:47]and the inter nodes are like the internet providing bits and then leaves and flowers aren’t funny. So I’m not going to make a joke there. And so they did that.

[00:17:55] David: [00:17:55] You’ve already done tremendous work.

[00:17:56] Sophie: [00:17:56] Thank you. It was a salt GRN model, so I had to go deep into the depths of like supplementary of material to work out what was happening. So the salt bit is just S is for Sachs genes. A is for AP one, it’s apathela one. The L is for L F Y, which has lifi, which has some other gene.

[00:18:14] And then TFL one is for terminal flower, one. That’s where the salt comes in and in the GRN model. And the whole model is based on a hill equation, which I’d never heard of, which essentially just refers to two closely-related equations that reflect the binding of ligands to macro molecules as a function of the ligand concentration.

[00:18:32]David: [00:18:32] Oh, yeah, it’s a pharmacology thing.

[00:18:33] Sophie: [00:18:33] Yeah. And so basically what you get is a set of seven partially decoupled differential equations in which they do a hefty amount of parameter fitting. But from what I can tell It’s maybe okay, so that’s one of the models. And so every time there was a plot in the paper day, they use that model.

[00:18:48] And every time there was a picture, or like, I don’t know if you watch the cool videos of these things growing, that was an architectural geometric model that only contained Merry stems and internodes.  And like, I just can’t tell you any more than [00:19:00] that except that seven partially decoupled differential equations with a lot of parameter fitting.

[00:19:04]but yeah, as you said, and then they went into the real plant and they like messed with the genes and it grew its little romanesco- like head.

[00:19:10] David: [00:19:10] Which is really nice. Like that’s a really nice thing to see just as a general science point. When someone uses a model, it should hopefully be predictive. It’s like, it should be a hypothesis generating things. So you could lead you to come up with ideas and then you go and test those ideas. And if you turn out to be right, then it lends weight to the model that you made.

[00:19:25] And that’s, that’s a really nice, rigorous way of doing things.

[00:19:28]Sophie: [00:19:28] Yeah, I agree. And I guess the only disappointing thing here is that they grew romanesco- like heads on things and as I said, I just didn’t really enjoy the texture of a romanesco cauliflower.

Addicted Fish

[00:19:47] From eating romanesco cauliflowers to ingesting fish that are full of methamphetamine,

[00:19:53]David: [00:19:53] So, yeah. Let me see if I can summarize this story. So drug users use drugs, drug users [00:20:00] pee

[00:20:00]Sophie: [00:20:00] Yes,

[00:20:00]David: [00:20:00] Pee goes into sewage with drugs. Uh drug goes into rivers and ocean,  fish breathe drugs.

[00:20:06]Sophie: [00:20:06] Yep. Fish get addicted to meth.

[00:20:08] David: [00:20:08] Yeah. So this is some work of the Czech Republic investigating her methamphetamine, a stimulant, which I’m sure most of our listeners will be aware of with a growing number of users worldwide might be affecting wild brown trout was the fish that they chose to examine.

[00:20:23]Sophie: [00:20:23] Yeah. And this has sort of come out of the, press release, which was also a conversation article that reports 269 million people worldwide use drugs every year. The bit that confused me then Dave was at, then they referred to the UN world drug report that 275 million people worldwide use drugs every year. So between 269 and 275 million people worldwide use drugs every year. And we’re talking about illicit drugs right now. I won’t say real pharmaceuticals, illicit drugs are still real pharmaceuticals in the sense that

[00:20:51] David: [00:20:51] Yeah. They still go in and do stuff.

[00:20:52] Sophie: [00:20:52] Yeah. we’re not talking about prescription medication here and, you know, and the idea is our sort of sewage treatment is not designed to filter out [00:21:00] these drugs.

[00:21:00] And then often a lot of the chemical components that like not the active drug themselves or the other things that go into the drug can have sort of similar effects, I think is the idea on these fit

[00:21:10] David: [00:21:10] So when you ingest the drug, it gets metabolized by your livers in your kidney and turned into other molecules because that allows your body to get rid of them. And those molecules can sometimes still be biologically active and you’ve peed them out. And that’s great for you, but they go into the river and maybe do things to the ecosystem.

[00:21:25] Sophie: [00:21:25] So, what they did is they got a bunch of trout, as you said, and they got 120 trout and 60 of those trout would have become the meth addicted trout. And the other 60 were our clean control trout. each of our groups went into 350 liter tanks for eight weeks. So obviously our clean trout or in clean water and our meth trout were in a tank with, I believe one microgram per liter of methamphetamine.

[00:21:50] David: [00:21:50] doesn’t sound like very much

[00:21:52] Sophie: [00:21:52] It’s not much.

[00:21:52] I looked it up 200 milligrams is fatal for a human. So it’s like a bit, but it’s not it’s. I mean, which is safe. Like we’re not just killing all the [00:22:00] fish at the beginning of the experiment going like, well, that’s not great. And then, Yeah,

[00:22:03] so they left them in there for eight weeks and then after eight weeks they took them out and they put the meth fish into withdrawal cold Turkey style in a drug-free tank for 10 days. And it was during that time, Dave and I actually really loved this part of the paper

[00:22:19]During that time they tested the fish’s preference for fresh water and water containing meth. And like when we found this article, one of the things that we commented was how do you test a fish’s preference, but they did it really well

[00:22:31] David: [00:22:31] Yeah. Yeah. So they came up with this thing or presumeably they had this thing lying around. It’s called a two current choice flume.

[00:22:38] And basically it’s where you have two currents of water flowing side by side in the same tank. But because the flow is laminar, smooth as opposed to turbulent, they don’t mix, which means you can have a meth-y one and a normal one.

[00:22:54]Sophie: [00:22:54] Yeah. at the top of it, you’ve got, your two channels coming in and then the two channels kind of joined in out what they’ve called, the [00:23:00] choice arena, where they fish has to make their choice of the water that they like. But you’re right, because it’s laminar flow essentially means it flows in layers.

[00:23:07] So there’s two sort of streams stay separate, but the fish can like swim between them, obviously, because there is an interface between our two laminar streams, but then Dave, this is where I go a little bit confused because apparently the conclusion is that the meth expose fish preferred water containing the drug and no such preference for the untreated fish.

[00:23:27] But if you look at the numbers that they quote, they’re very close to each other. So they say that the controlled fish, they talk about two different things are crossing from one side of the choice arena to the other. They don’t specify which way. And then they also talk about the total amount of time spent in each of the streams for each of these groups. So they’ve said that  the controlled fish cross from one side of the choice arena to the other during 21.6% of all observations, right? So those are our controlled fish, the meth fish cross from one side to the other in [00:24:00] 21.1% of all observation. So the crossing is quite similar in the sense that it’s only 0.5% difference in the number of times they cross. The control fish spent 41.5% of all observations in the meth water.

[00:24:15] The meth fish spent 50.9% of all observation time in the meth water. So that’s only a 9% difference. So like the clean fish, they both seem to like the meth water and the non meth water fairly. I know, I know 9% is not nothing, but it’s also not hugely different.

[00:24:33] David: [00:24:33] Yeah. So it may be that, we’ve only got, 60 animals in this and when you look at the withdrawal data, so when you look at the withdrawal data, they compare the meth fish with the non meth fish, as opposed to comparing either of them to baseline.  presumably that effect is bigger.

[00:24:48] So they may be just weren’t statistically powered enough well enough to make that distinction.

[00:24:53]Sophie: [00:24:53] so they looked at behavior, but then the other thing that they did was they looked at the brain chemistry as well. right dave?

[00:24:58] David: [00:24:58] yeah. they found that [00:25:00] basically the, meth fish were more likely, generally speaking to be in the

[00:25:04] Sophie: [00:25:04] meth side.

[00:25:04] Which is true. Yeah, it is generally speaking. That is true.

[00:25:07] David: [00:25:07] Yeah. And the controlled fish were less likely to be in that side. And then when you looked at the trials data withdrawal, that difference gradually disappeared to the extent that they were no longer significantly different.

[00:25:17]And yeah, they found that this, likelihoods, the probability that they would spend time in the methy section was positively correlated, which is to say it varied at the same time as, the amount of drug that could be detected in their brain. Basically they’re saying there was something in the brain that could correlate and that landed weight to their argument, they said.

[00:25:35] Sophie: [00:25:35] Yeah.

[00:25:35] And, you know, whenever we talk about something that involves animals, I like to look at how the animals being treated and, uh, from the paper I quote immediately after each behavioral observation, individual fish were measured, weighed and killed by cervical dislocation, followed by exsanguination.

[00:25:51] Which I love, like, obviously they’ve got to, but I just feel like I have not read that many papers that include the word exsanguination, but just in case you’re worried, Dave, the method was approved by [00:26:00] the valid legislative regulations and then they whole ideas and they dissect the brain tissue and then they weigh it and they store it and then they can do their methamphetamine and amphetamine analysis.

[00:26:10] David: [00:26:10] And for the listener, we should probably just say exsanguination is where you remove the blood

[00:26:13] Sophie: [00:26:13] Yes. if you’re not a big fan of the X-Files, you wouldn’t have heard that word for the first time as an eight year old.

[00:26:19] David: [00:26:19] So it’s basically a double measure. So the neck is broken to kill the animal, exsanguination is done to really make sure that the animal is not alive and therefore not suffering.

[00:26:26]Sophie: [00:26:26] Yeah. And so, and what they did is when they looked at the brain chemistry of the other exposed fish, There was several detected changes in the brain chemicals, which would correspond to what we would see in human addiction. And this was even after the behavioral effects had waned after the 10 days of cold Turkey withdrawal.

[00:26:44]David: [00:26:44] Yes.

[00:26:44]Sophie: [00:26:44] Yeah. So the suggestion there is that meth exposure could have long lasting effects in fish, but sort of just as we see in people. So I  sense.

[00:26:52]David: [00:26:52] It makes sense. And they also make the point that, so apparently this is known that, fish can develop drug addiction such as behavioral [00:27:00] dependencies, and it’s related to the dopamine reward pathway in a similar manner to humans, which is one of the reasons that they’re used. So apparently Fisher used to study neurology of addiction.

[00:27:08] Something else I found interesting in the paper was we talked about the likelihood that the meth fish, would go to the meth side and the controlled fish goes to the control side. The controlled fish seemed to spent preferentially less time on the meth side. So it’s almost like they don’t like it. Like, it’s almost like they can, if you’re a naive fish has never seen meth before you can smell the meth.

[00:27:29]Sophie: [00:27:29] yeah, the meth fish, they just like hung out in their meth tank. They had no choice, but the non-meth fish when given a choice were just like, no, I don’t like it.

[00:27:38] David: [00:27:38] Yeah. And so, as for, the take home message from all this, they make some really good points in the conclusion. So they say that fish exposed to environmental concentrates and methamphetamine. The problem with them developing addiction is that they may choose to preferentially hang out near wastewater treatment plants and where the affluent comes out and that’s, which is gross.

[00:27:58] because there’s a growth sentence, [00:28:00] which is wastewater effluents are often nutrient rich, which is basically the fish love the poop

[00:28:06] Sophie: [00:28:06] Well, I mean, that’s, you know, that’s why we use poopers fertilizer.

[00:28:09] David: [00:28:09] Yeah. but basically they make another really good point that if  the fish are chasing a drug reward that may overshadow natural rewards, like foraging or mating, that the fish needs to be doing it in order to like, look after themselves as a species. And bad.

[00:28:22] Sophie: [00:28:22] A

[00:28:23] David: [00:28:23] yeah, so it’s actually, it’s a very interesting and, probably important study.

[00:28:27] I think.

[00:28:28] Sophie: [00:28:28] And my last question is how long do you think it took to get ethics approval to put fish in a tank full of methamphetamine?

[00:28:35]David: [00:28:35] That’s a good question. I’ve got no idea what ethics advisory committees are like in the Czech Republic, which is probably a big part of the question.

[00:28:42]Sophie: [00:28:42] yeah.