Episode 30: Fayth tan on Regeneration and Queer Identity

Illustration of Planaria from Thomas Hunt Morgan's Regeneration

Image: Fig. 24 from Thomas Hunt Morgan’s Regeneration, illustrating the results of one experiment in planarian regeneration.

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Charles 0:00
Hello, and welcome to Assigned Scientist at Bachelor’s. I’m Charles and I’m an entomologist.

Tessa 0:05
And I’m Tessa and I’m an astrobiologist.

Charles 0:07
And today as our guest we have Fayth Tan. Fayth is a graduate student in biology at Caltech and received their BS in marine biology from UC San Diego. Their background is in evolutionary developmental biology and their current research examines how animals evolved or lost the ability to regenerate various body parts. Fayth, welcome to the show.

Fayth 0:27
Thank you. So excited to be here.

Charles 0:30
Excited to have you. So to begin with, we normally like to ask people, how did you get interested in science?

Fayth 0:36
Oh, boy. I feel like I took a very nonlinear path to science. I think that like many scientists, I started off as like, the very intensely interested in specific things type kid, I was definitely the dinosaur kid, I was definitely very didactive about dinosaurs to my very few friends. But yeah, I was definitely that kid. And then I went to art school in like middle school and high school, and then burned out of that and I was like, I need to do something new with my life. When I went to undergrad, I found my undergrad advisor, who kind of reignited that like dinosaur kid feeling with the weird animal that her lab was studying, which was … jerboa, which I’m like – I don’t know if you’ve seen a jerboa before, but they’re like, the desert rodents with really big feet. And they like, bounce around, like, you know, kangaroos. And I don’t know, when, when I show them to people, I think the funniest reactions that I’ve gotten are like, what kind of Pokemon is that? And, what did you do to that mouse?

Charles 1:51
I mean, both seem pretty valid to me.

Fayth 1:56
That’s how I formally got into science, I guess, like through through that undergrad lab. And I kind of reconnected my interest in being very intensely interested in very specific things, which, like, science is a good platform for that kind of personality, I think. And also, I found out that academic science was way more creative than science is usually taught at like, middle and high school level.

Charles 2:22
Wonderful. Well, then, how did you get interested in what you’re doing now?

Fayth 2:26
I guess, in evo-devo you… which is I guess, talking about evolutionary development biology… like there’s a lot of overlap with regeneration, I think, because a lot of regeneration research is, is looked at from like a developmental point of view, as well as an evolutionary point of view. I just thought that animal regeneration has a really interesting history and lifeform tradition. And basically, I think that that impulse to study something really fundamental, biologically curious was really appealing to me, just because like there’s something inherently compelling about, like, cutting things off and watching it grow back, and…

Charles 3:03
It does tap into that kind of weird kid impulse to just kind of do weird stuff.

Fayth 3:09
Yeah, gosh, I feel like just tapping into that weird kid impulse…

Tessa 3:14
Yeah, take things apart, put them back together… or in this case, watch them put themselves back together, I guess.

Fayth 3:19
Yeah. Yeah. It’s like that sort of like, but what will happen though, and I it’s so interesting to see that captured in like scientific history, because a lot of it is very, you know, detailed observational studies, the kind of things you probably don’t see as much in, like, regeneration literature now, suddenly, which is a lot about, like, understanding the molecular mechanism behind the process. But, you know, people used to experiment on like, a really diverse array of organisms and really document the process really carefully. Because it was in that period of science where like, the qualifications were mostly that, like, you were rich enough to just wander around.

Charles 3:59
[laughs] Yeah.

Fayth 4:00
Wander around the beach, pick up some weird, like…

Charles 4:03
People at the beginning of, of what we often consider contemporary science, really, were living high on the hog in terms of the low hurdle that they had to clear for publish-ability. Basically, you could get a publication out of, I saw something weird.

Fayth 4:23

Charles 4:24
Which they just won’t let you do anymore.

Fayth 4:25
It’s an insult, really. You can’t just be like, well, it was weird. And I saw it, here’s some drawings, or, Oh, it would be like, entire philosophical, like, treatises on the subject. And, and they’d be like, here are my thoughts which clearly extrapolate to universal laws of the scientific world. Or I’m just gonna submit this for publication and all of it is going to be taken incredibly seriously.

Charles 4:54
Those were the days. They also weren’t the days because science was even more racist than it is now.

Fayth 5:01
Yeah, it’s like who got to do that kind of thing?

Charles 5:04
Yes. Pros and cons, pros and cons.

Fayth 5:07
I think it’s, I think it’s owed to like marginalized people. [laughs] Like, we didn’t get to do that, then – let me publish the paper on my observations about weird animals.

Charles 5:19
It’s only fair.

Fayth 5:20
It’s only fair.

Charles 5:21
It’s only fair.

Fayth 5:22
The hundreds of years of hits that man.

Charles 5:25
Well, then. So I think a good starting place might be to define what the parameters of regeneration actually are. Because I think this is one of those concepts in science that a lot of people have an awareness of, but their awareness comes from, like, Spider-Man.

Fayth 5:47
Yeah, that’s true, right? Like there’s that very pop culture image of the things just growing back suddenly. I think that the is a interesting uses of the word regeneration in the literature. And this is just sort of like way. I guess it’s just a medical way, I think it’s important. Like, this regeneration isn’t like replacement of an entire like organ or an appendage. And then there’s like regeneration on like, a cellular level. And I guess, like most people have viewed those as two distinct things. But perhaps there’s like more overlap than we think.

And I guess like, I, I think that I have unusual conception of the idea of regeneration, because I think that it has a lot of intersections with organism like homeostasis in general, it has a lot of intersections with very fundamental organism processes, like growth, potentially, like reproduction. And if we can understand those connections, maybe we can understand the process of regeneration much better because I feel like that pop culture idea of like the exceptional nature of regeneration, right, like, like the idea that they’re like superpowers based on that, like, this is something mythic, this is something weird, without realizing maybe that like, it’s part of these really fundamental processes. It’s seen as something really strange, but perhaps the ability is more interlinked with much more mundane biological processes.

Tessa 7:21
Yeah, it sounds like, you know, it’s- the processes involved are the same you see in other organisms, they’re just kind of, like, scaled up,

Fayth 7:27
Right, yeah, exactly. I guess, like, the way that we think about, like, for example, human regeneration, specifically, like it gets a lot of hype, it gets a lot of like, Whoa, this would be remarkable, what if we could just like, cut off a limb and grow it back? But like, the thing is that you know, us, the cells in our body, do turnover regularly, like we maintain…

Charles 7:53
Could you expand more on the kind of research that you’re doing in regeneration, specifically?

Fayth 7:59
My current firstpreprint kind of focuses on inducing regeneration in animals not typically thought to be regenerative, we basically induce some degree of regeneration in three really diverged species, like evolutionaryily – we, it’s like the jellyfish, the fly and mice. And we induce regeneration in these animal’s bodies… like with different body parts with you know, obviously they live in very different environments, who are thought to, you know, which are very like different biologically… with an amino acid, leucine, as well as the growth hormone insulin. And this was a kind of a proof of principle thing, I guess, to show that you, one, can induce regeneration beyond what is thought a normal or typical extent, as well as you can basically influence an organism’s regenerative potential through external stimuli, which I think is a relatively, relatively different idea of regeneration because most regeneration work is done in animals that can regenerate with, you know, lots of axolotls, lots of Planaria, and so…

Charles 9:18
I think probably people will be familiar with axolotls, and if they aren’t then Google because they’re cute. But, could you describe the second group that you just listed?

Fayth 9:27
Yeah, so Plararia are these like low flat ones, and they are known for being incredibly regenerative. You can cut them up into little bits and each little bit will turn into an independent worm. Cut off, they can regenerate heads, they can regenerate tails, like it’s really an amazing animal. I think one cool thing actually, sorry, this is my Planaria tangent…

Charles 9:50
This is a Planeria-positive podcast.

Fayth 9:54
Oh, thank you very valid. The… when I was talking about like the history of that, of the field and how people used to just like, pick up stuff and do stuff. Thomas Hunt Morgan, who’s probably better known for its genetics work in Drosophila, his first love, I guess, was actually regeneration in Planaria. He has like a little book dedicated to the question of regeneration in Planaria. And you can see him be like, oh, what’s the smallest piece of Planaria that could possibly regenerate?

Charles 10:28
The degree to which old foundational studies would not pass IRB approval is just astounding to think about.

Fayth 10:39
Right, yeah. And the thing is, like, because it’s a whole, like, short book, you get to see his whole thought process behind the thing behind each of the experiments he decided to do. And that’s just not something that we we see very often anymore because like, your papers have to be like, excellent. Okay, as long as you can see that he was confused by some of his findings, or like, he’s like, what does this mean? He’s like, I don’t know. Yeah. And later on in life, you would actually tell people that regeneration is, is a problem that won’t be able to be solved.

Charles 11:18
Well, it wasn’t in his lifetime, because that sucker’s dead.

Fayth 11:23
I know, I like to, I like to open presentations with that quote, just just to be like, hey, he said it couldn’t be done. And do I know anything? No. Do I know… [laugher from all] Do I know how this works? Absolutely not.

Charles 11:41
And you know what, you’re valid?

Fayth 11:43
Yeah, I’m so valid. [laughs].

Charles 11:45
Well, I’m actually interested in what makes an organism something that we would think of as being particularly regenerative, versus organisms that we don’t typically attach that to, both in terms of like, if there’s a historical aspect of, there are just certain things that we’ve just decided are regenerative and that’s sort of been fixed in people’s minds, and or if there are actually sort of divergent physical properties between different organisms that make some more able to regenerate in ways that others can’t or don’t.

Fayth 12:20
Right, I think this is a really interesting question, because, like, I do look at this problem from like, an evolutionary point of view. And the first thing that I kind of want to think about was, like, are there some basic physiological correlates for animals that tend to be highly regenerative, right? And there were a few things that repeatedly come up. And I think that, you know, suddenly review articles have talked about this before, but one like they tend to be juvenile animals, for example, can regenerate more readily than adult animals.

Charles 12:54
Well, this is actually, this is interesting to me. Let’s dig into this first, okay, take the off ramp to the insect side road. Because the, my understanding… my awareness of this sort of is, in thinking about, for instance, insects, particularly hemimetabolous insects are the ones that hatch out of the egg and look like less complicated versions of their adult selves, nd there’s often you often read like, if an insect in like its third instar, which is the third stage between molts, loses a leg, then it can sometimes get that leg back when it molts again. And that’s just a fun fact that I know, and that I can contribute.

Fayth 13:37
Yeah, so much foundational insect regeneration stuff is in cockroaches, so.

Charles 13:41
[triumphantly] Yeah! [laughter] You’re all welcome. I didn’t do it, but I’m gonna take credit.

Fayth 13:48
A win for the cockroach community.

Charles 13:50
Yeah, but I guess, I guess to relate this back to the highway that we were cruising down – is there a difference that we see in juveniles of groups, like members of Ecdysozoa, which is the broad clade that includes like all the arthropods, and close relatives where they do molt and they grow through molting basically, is that more common than regeneration and like other kinds of juveniles? Or is it a general property of, while you’re growing, it is easier for you to grow back larger stuff?

Fayth 14:24
Right, so, I think this is a really good correlate in like Ecdysozoa, for example, where you know that constant growth means that you can regrow things. And there’s also, I think, relatedly, animals that have indeterminate or determinant growth.

Charles 14:41
Well, let’s… what does that mean?

Fayth 14:43
Right, an indeterminate growth means like, it’s an animal that will keep basically increasing in size throughout its entire lifetime. Whereas determinant growers will have kind of like a set, final size quote unquote, when they reach adulthood. And I think it’s really easy contrast to that is, is like, for example, segmented worms that will keep adding segments throughout the whole lifetime, so they just get… it’s just like longer and longer worm.

Charles 15:13
This is a new worm fact that yeah, it’s really gonna enrich my life, I think.

Fayth 15:18
Yep. So you know, a lot of like, polychaete worms, so a lot of those marine worms that that you see the with, with segments like they’ll just keep adding posterior segments throughout the lifetime, and how big they get is basically constrained only by their lifespan mostly. And then there’s determinant growth – for example, also a segmented worm like, like leeches that have a specific number of segments that they’re going to reach. And then they they stop. Leeches are a really interesting case, because more segmented worms can regenerate really easily. If you just cut off the posterior part, they’ll regrow that posterior pot, but leeches cannot. And they’re like the one of the notable exceptions in that claim.

And I think, yeah, so we have like, you know, a question of juvenile versus adult, indeterminate versus determinate growth. And then I think the last big correlate, like broad brush correlate is whether something is warm blooded or cold blooded, because cold blooded animals tend to… if you, especially if you think invertebrates, cold blooded animals tend to be able to regenerate better than warm blooded animals, broad, broad brushstrokes that always exceptions, these cases. And I also think that the exceptions are interesting. But like, if you think of, for example, zebrafish, which is like well known to be able to regenerate like it’s heart, fins, versus like some something like us, where I don’t think that would go over quite as well.

Charles 16:48
Spider-Man lied.

Fayth 16:49

Charles 16:51
Well, he did become a lizard.

Fayth 16:53
Yeah, exactly. So he was like that, quote, let it life, is it?

Charles 16:58
Well, I’m interested actually, is the difference… is there a property related to being cold blooded, but makes regeneration easier, or is it kind of in the area of it is probably related to other characteristics and it just happens to map onto those? Does that make sense?

Fayth 17:19
Yeah. So I think that all the correlates that I’ve mentioned, they all kind of relate to some sort of energy expenditure, and the differential amounts and rates of energy expenditure. So if you think about like a warm blooded animal, it needs to expend a ton of energy just because… sort of maintaining organismal homeostasis.

Charles 17:39
Well, Could you briefly, [jokingly arrogant] just for the plebes in the audience, could you define organismal homeostasis?

Fayth 17:44
Right, it’s, like, kind of like your your your steady state, right, you’re equally your your animals equilibrium state that it would generally be right if it if it was continuing to be alive day in the same place, same place quote, unquote in a physiological sense, it actually takes a ton of energy expenditure. Just because everything look quote unquote normal biologically, quite a lot of things have to be happening to maintain a base rate level of various physiological parameters at which an organism is comfortably alive.

Charles 18:17
Well, you can’t see me because we’re not using video but I’m shaking my head at the trials and tribulations [Tessa chuckles] of being a mammal.

Fayth 18:26
Right? Everyone’s like, oh mammals, they’re so cool. I’m like, No, it’s [laughs]

Charles 18:32
We’re not even a good… like we’re not even hairy, which is the main selling point of mammals.

Fayth 18:38
Yeah, we’re not we’re not fluffy. We got a, we have a spine that hurts a lot, can’t regenerate really well at all…

Charles 18:48
All this for a large brain and bipedalism! Was it worth it???

Fayth 18:52
Yeah, was it worth it. This is the large brain, to be able to comprehend the, the trade offs that we made.

Just how sad it is that we don’t have fur all over our bodies. Yeah, although I will say I don’t like other primates that much anyway. So really, what I’m saying is that I wish humans were all cats.

Yeah, man.

Charles 19:19
I gotta live in my truth. But okay, so I we took a long off ramp, and we’ve sort of been milling around the little town, but maybe we can get back on the highway. And we were talking… you were talking about how juveniles often have more regenerative capacity than mature animals.

Fayth 19:42
Yeah, so if you think about animals that have regeneration abilities as juveniles, for example, a frog – like tadpoles can regenerate tails and they can regenerate the rudimentary limbs up to a certain point, but frogs generally. if you amputate a limb, you’ll just get this like cartilaginous stump, but you won’t get the whole foot. But if you think about the process of growing up, it’s a process of really intensive energy expenditure. And I guess what I’m getting is that all the, all the processes that I’ve listed involve some sort of metabolic process at an organismal level, they all kind of come back to an organismal metabolism that can either change the amount or rate of energy expenditure. And I guess like, my research hypothesizes that if you can, you can sort of change the parameters of animal metabolism, you might be able to change that regenerative ability as well.

Charles 20:48
Can we talk more about the sort of mechanisms that control regeneration? Like molecularly?

Fayth 20:59
Oh, boy. Okay, so I think that molecularly you do see like the same kind of like pathways come up. And you do, I think, see a lot of reactivation of developmental pathways, uh…

Charles 21:23
Could you describe what you mean by like, metabolic pathways?

Fayth 21:26
So certain nutrients, certainly, environmental stimuli, and in my case, or nutrients, or amino acids will basically stimulate the activation of molecular pathways that sort of tell cells to do certain things like, hey, it’s time to grow, it’s time to proliferate – or, hey, this is, it’s basically taking an input and turning it into a cellular output.

Charles 21:51
What are the steps that that kind of pathway entails?

Fayth 21:55
You know, like, I think I’ve been talking about it in incredibly general terms, and that’s because I’ve been looking at it from such a broad point of view that those pathways are kind of going to differ from organism to organism.

Charles 22:07
Could you describe sort of an exemplary one?

Fayth 22:09
So a signaling pathway is basically a way to propagate information between cells, right, you have all these extracellular signals called ligands, usually, that bind to a receptor. A receptor will, will then send more signals through a network of interactions, usually through other proteins, whether directly or indirectly, and this will culminate in some sort of response. And this response can be like, Hey, I’m activating more genes, or it can be like a specific physiological or cellular response.

Charles 22:43
So a pathway is basically like a way of cells, or something, getting a message and then causing sort of a cascade of different interactions that causes something to happen. Like at a molecular level.

Fayth 22:59
Yeah, yeah.

Charles 23:00
So stepping back in from the pathway tangent… I think you were talking about pathways.

Fayth 23:08
Yes. So the thing about, I guess, a lot of like, developmental pathways and how they’re typically studied in regeneration, they tend to be pretty conserved. And they tend to be the same ones, which is why people have tried to study this.

Charles 23:26
Sorry to interrupt you, but I think… you’re using a lot of great evolutionary terms, but conserved just meaning that they don’t, genetically, they haven’t changed a lot between different organisms and over time.

Fayth 23:41
So a lot of these pathways are studied in regeneration, because they’re used in development. So it’s kind of like, if you’ve built this one thing before, maybe we can activate it to build this thing again. So for example, in mouse digit regeneration, there’s a lot of study of like the wind pathway, if, finally, my specific example, because I realized that… no, none of the other animals in that preprint actually, like normally regenerate on their own. And so yeah, another side note, like people seem to be the most surprised about the mouse result. But mice do actually have some limited regeneration ability in the, in the, in the very distal most – like the really edge of the finger, basically, what the workday was like, push that back, push that point back. And that’s actually pretty consistent with for example, like human children’s ability to regenerate the very tip of the fingers.

Tessa 24:47
I was actually thinking about that, yeah.

Charles 24:48
How much is the tip? Like?

Fayth 24:52
How much is…? So actually for mice? It’s been really rigorously quantified. It’s like, it’s about the first third of the first phalange of the finger, and it’s a very first third of that for mice, and it seems to be about the same for children.

Charles 25:10
So if you, if you got a child – why don’t you go test this out? Don’t do that, that would be child abuse.

Fayth 25:17
Do not, do not test that out.

Charles 25:22
But, good news if your kids really into knives…

Fayth 25:26
It would be fine, actually!

Charles 25:31
Kids are into all kinds of… Listen, if your kid is really into knives, kids are into all kinds of stuff. No judgment, no judgment. So I think an interesting question then is, what signals does the body get to regenerate?

Fayth 25:46
So I think this is a question that’s like, kind of like, up in the air right now, in my at least, my work. And I think that basically, there’s a connection between that signal to, for example, grow or proliferate, like there may be a specific energetic barrier to regeneration – that is, it’s kind of like upstream of any sort of developmental reactivation. Perhaps, if an animal has enough energy to regenerate, it might be more inclined to go that way. There was a paper about comb jellies. Like, do I need to explain what a comb jelly is?

It’s… they’re shiny, and they live in the sea.

Yeah, this shiny, shiny, nice, shiny blob. These comb jellies basically, they, they tested their regenerative ability under different, like, food regimes. So they fed some of them a lot of food, and then some of them will starve. And usually you, you, they typically are known to have the ability to regenerate like their whole body. So if you cut one in half, you’d expect it to grow back.

Charles 27:05
This is a real Ship of Theseus problem, if you’re regenerating your whole body,

Fayth 27:10
Yeah, you’re like, you know, making you… basically, under the starve condition, some of them were like, you know what, I’m fine. And they just basically wound heal, and live this little half animals, and so that you had a much higher rate of regeneration in a regenerative animal that was given more food. And so I kind of want to look at this question to animals that don’t usually regenerate. Like if, if the environmental parameters were more favorable, would they be able to do it?

Charles 27:40
Well, I have another question, which is, so I think, an intuitive thought that a lot of people would have is that it’s difficult for stuff like mammals and probably vertebrates in general, to regenerate limbs, for example, because those are very complicated structures. But is this actually, like, a legitimate distinction that a human limb is more complicated to regenerate than, for instance, an insect limb between instars? Or is this just kind of a mammal centric point of view, and there are other things that are really restricting the ability to regenerate those kinds of things?

Fayth 28:26
I mean, this is one of my favorite – you caught this before I could get to it, because yeah, I think that is that perception of, Oh, uh, you know, a human limb is a really complex structure. And it is. And so that’s why it’s difficult to regenerate. But it’s true, like, you know… even insects aside because people don’t care about them enough.

Charles 28:48

Fayth 28:49
I know. Axolotl limbs are really a, you know, homologous to human limbs, and yet, they seem to be able to do it. And so I do wonder if it’s a question, and this is, this is all speculation, I wonder if it’s a matter of evolutionary trade off rather than the intrinsic complexity of a structure? Because, for example, if you think about the steps needed to regenerate a whole limb, like that’s a lot of cell growth, that’s a lot of cell growth during injury, and there’s the potential for things to go wrong. And that’s why I do think that there is a probable trade off there between being able to regenerate and, for example, and like preventing tumors from occurring.

Charles 29:35

Fayth 29:36
Yeah, there’s this… perhaps it’s because, you know, the risk is just too great. Or the energy expenditure. Like there’s too many things that could potentially go wrong for it to be worth it to regrow an entire limb, maybe in mammals. I do have a bug aside.

Charles 29:55

Fayth 29:57
So like, I think like, I like seeing people react to the preprint. Like, most people are most surprised about mice, but like, you know, you brought up that insect limbs are really complicated structures, too. And I was actually most surprised about flies, because…

Charles 30:17
We’re gonna have to get specific… are these Drosophila?

Fayth 30:20
Yes, these are just Drosophila… I was including them because they were there.

Charles 30:25
Yeah, imagine me doing a great big eye roll, but also kind of a shrug, like I get it. The eye roll is to suggest that [dismissively of course it was Drosophila. But the shrug is also to suggest, [resignedly] well, of course, it was Drosophila.

Fayth 30:41
Just in brief defense of Drosophila, this is Drosophila in a, in a different light, because not many people, not many people study, like, adult Drosophila in a physiological level, which is kind of a surprise to me. The thing is that a lot of insects that undergo metamorphosis, are thought to be like, they’re not supposed to be able to replace anything, like – that’s it, especially considering an insect replacing a relatively complex structure for a body that it’s going to use for maybe like, a month more. I think that, that’s like more remarkable than a mammal being able to replace parts that it’s gonna use for like, a couple of years.

Tessa 31:27
By the way, um, are you at all familiar with the work Mike Levin has been doing at Tufts University?

Yes, I have just seen a Michael Levin talk.

Okay, because one of my lab mates is a collaborator of his.

Fayth 31:39
I see! So cool. Man, I think that the way that we think about regeneration is, like, on the same vibe, which is – you can cause broad upstream disturbances that will result in really specific downstream patenting events. But what Yeah, I just saw a talk about the bioelectricity stuff in both frogs and Planaria, and being able to like predict which, uh, which perturbations needed to be made to cough out a specific path.

Tessa 32:15
Yeah, yeah, I think it’s really mind blowing. What my lab mate has been particularly focused on is like figuring out, okay, where is this information actually stored? You know, how does it know, especially when you’re dealing with Planaria, and when you chop them up into little bits, how does it know to like, regrow a whole rest of the organism?

Fayth 32:34
Yeah. And actually, interestingly, that book by Thomas Hunt Morgan, like, he asked that question, too, but he has no way of, like, testing it. And that’s why he was trying to cut Planaria up into the littlest bits possible. Like, that was one of the historical questions that people had for organisms that could regenerate large parts of the body, they’re like, okay, which bit is the bit that remembers what the body is supposed to look like? Better cut it into as little bits as possible to find that specific bit then. And then they couldn’t find a specific part of the body that stored that information, and it was very confusing at the time.

Charles 33:14
How does the body, or how to various kinds of bodies, recognize that they have suffered damage that would require regeneration at the level of… I think you mentioned in Zebrafish is regenerating an entire limb, or fin.

Fayth 33:32
Right. So I think there’s this, like the initial injury response, definitely, and then there’s a question of positionality, as well, by how much damage has been done, how much things do we have to repair? And, man, I’m not super clear on the specifics of this, but like, there must be some way that the cells understand that there’s something missing and I think if you walk with my axolotl blastemas, and a blastema is like an undifferentiated group of cells that produce the regenerated organ, they found that basically, those cells aren’t as naive, quote, unquote, as, as people thought they were… that they tend to have certain, to grow… they tend to know that they are supposed to grow certain things. They tend to be more restricted in terms of what they will become and can become, and it’s unfair of like how… I think it’s still unclear how they know that to grow back exact things…

Charles 34:45
Well, this kind of brings to mind – but are stem cells involved in all this?

Fayth 34:50
Um, I mean, typically, like, [drawn out] yeees… I think there’s a lot of debate on how stem the stem cells are in different contexts of regeneration, and I think like…

Charles 35:02
Oh, like does sociology count as like a social science, is that part of STEM?

Tessa 35:02

Charles 35:02
Bad joke! [general laughter]

Fayth 35:02
I think that, like the reason why I’ve been so cagey about my answer just because like I, I’ve been talking about it in like, really broad context, and I for sure know that there’s going to be some specialists being like, it doesn’t work like that in my field! And like, definitely the way that I’ve been looking at regeneration is pretty atypical, because it’s across so many different species, across so many different organs, contexts…

I think the consensus is that the stem cells involved in regeneration aren’t like totally naive, right? That they, for example, have certain lineages that they will become. So in the axolotl, there are cells that will become bone, that will become cartilage, that will become like vasculature, or they aren’t always the same cells. And you can kind of pick up those differences with like single cell type sequencing techniques, which you couldn’t before.

Charles 36:12
I was actually… thinking about bone, is there a demonstrated difference in sort of regenerative capacity between structures that we tend… that, you know, various kinds of organisms just have at the outset, versus things that they do develop over time. Like, thinking about bones, I think that, and I’m gonna project this onto people in general, because in my brain, that feels like kind of a sticking point, because you’re just kind of born with your bones, you just kind of have them. And so there’s not really a part of your life where you lose the bone, and then it comes back… although we did just learn that children can chop off part of their fingers, and probably get them back. So that’s not completely correct. But like, does that make sense? And I think, in thinking about jellyfish, or whatever, it kind of feels like their bodies aren’t really [laughs at self] real to begin with, because it’s just a bunch of goo in the ocean, how complex can that be really?

Fayth 37:23
Bags just floating around the ocean. No brain just goo… Sorry, what was the question?

Charles 37:31
Well, I’m not sure that it really was one. I mostly wanted to talk about just the horror of bones, I guess.

Fayth 37:40

Charles 37:41
You know? The curse of vertebrates had to happen for the blessing of cats.

Fayth 37:47
Yeah, it’s a, it’s a shame about the whole vertebrate thing.

Charles 37:51
It’s really an unfortunate evolutionary side path that we all went down.

Fayth 37:58
Yeah, I think that I think urochordates had the right idea. When, when they were like, Oh, we almost have a spine, but we… I think we’re going back to like sponge shape, actually.

Tessa 38:11
What, you know, assuming your research continues to go along, as it is like, what discovery would you be most excited to make?

Fayth 38:18
Oh, man, I would love to understand that trade off – like why we don’t regenerate, for example. If my research doesn’t work, and I understand why… I wouldn’t be, I’d be really interested to, to know what those evolutionary trade offs have been, such that a lot of them that made in regeneration just doesn’t work out. Because I think like the current therapeutic approach, and this is, this is this is one of my other rants. Because I think so much regeneration research is done in the context of like biomedicine. And it’s kind of like, oh, it will be a unequivocably good thing to be able to make humans regenerate. But I’m like, Why though? Why can’t we regenerate? What, what kind of horrors are we preventing? What what kind of gross…

Charles 39:14
Our limbs would be too powerful!

Fayth 39:18
You know, what kind of gross biomedical horrors were we, was the evolutionary selection preventing?

Charles 39:24
Well, actually thinking in in the context of biomedicine, I think, and this could just be my limited perspective, but it seems like people normally when they bring that up as a possibility, they’re talking about regeneration in, for instance, amputees. But is there also research that’s done on more internal stuff, like if you suffered organ damage, instead of having to get a transplant regenerating part of your organ?

Fayth 39:54
Yeah, I think that is definitely definitely like stem cell therapy stuff. Try to, try to, try to like, grow that back. And then of course, like, with a lot of organ transplant stuff, you get the question of like immune rejection. And if, if the donor could receive their own organ, that wouldn’t be a problem anymore. Not super familiar with the specifics of that, because I’m not a biomedical person, um…

Charles 40:22
Who wants to be, who wants to be?

Fayth 40:24
Yeah, that was my that was like, my one… I think when when Charles reached out I was like, I don’t know anything about the medical implications of this. I’m like, I think weird animal do cool things!

Charles 40:40
I feel a lot… I think ASAB will always be a welcome home for people in your position who are, like, not doing the sort of most high profile version of whatever. Because Tessa is in astrobiology and I am in history and philosophy of biological taxonomy as it relates to insects, like neither of us are really, we’re not going to get invited to do a TED talk. Let’s say that. Tessa might if they… if they find life.

Tessa 41:14
Yeah, as it is right now…

Charles 41:15
But I, I don’t think I’m going to be.

Fayth 41:20
They’re like, don’t come to us unless, unless you have aliens. No alien, not interested. Which I, I think it’s very unfair. I think, I think the fact that you guys aren’t getting TED talks is more reflective of the society that we live in than any inherent flaw in the research itself.

Charles 41:36
Thank you so much.

There is actually another part of our podcasts. But I forgot to tell you about this beforehand, I think we like to ask our guests to weigh in on one of several recurring questions that we have. And I like to send them to people beforehand, so that they don’t get, you know, caught off guard, and they have time to think about it. But I forgot, I think I thought about it, and then I got distracted by something. And then I didn’t do it. Um, is it okay, if it’s in space, this is kind of an open just go? What like, is it gay, if it’s with an alien is a gay if it were 400 years in the future, and our concepts of sexuality have totally changed. free space.

Fayth 42:16
This is all incredibly cool questions. I was thinking for medical transition technology, I was just like… good health care.

Tessa 42:25
I mean…

Charles 42:25

Fayth 42:29
The invention of socialism? Okay, done! [laughs] But for, like, definitely the more like, philosophical bent ones. I think, I think, I think I’ve heard that, is it gay if it’s in space one. And so I, I’ve definitely, like thought about that. And I think that, like, it depends on the context in which space is, if it makes sense, I like to, you know, I guess like in pop culture, there’s, like, two common paradigms of, like, what space, quote unquote, represents. And I’m coming at this as someone who does not study space, and so I only have…

Charles 43:19
You know, who needs to?

Fayth 43:23
WHO has that frame of reference? [laughs]

Charles 43:24
No offense to Tesla and all the space people in our audience.

Fayth 43:29
And so, I think there’s like, one space is a site of this, like the hyper capitalist dystopia space, where like, Elon Musk owns the, the, the rare earth moon mine. But, you know, and I think that there’s, related to that, there’s being gay or being queer, as, as a mode of, like, categorization, and like othering, and a way to create that underclass needed for exploitation, which is like the cynical reading of all of this, right? Like, it’s still going to persist because, like, because people need to other other people in order to see them as less than and, like, justify exploiting them. I think that’s the pessimistic, pessimistic pop culture view of this.

But the other one, which I’m much more fond of, and I hope that is the one that like comes to pass, is that… is to see space and queerness as possibility, as potential, as really the ability to think about new ways to relate to people, new ways to form community, like ways to, um, break free of every assumption and every oppressive societal contract that has constrained the ways that we relate to one another, that we relate to our communities. And I think that like, that’s, that’s a really interesting idea. Especially when it comes to space, where it’s seen as like this, like, sort of broad potential, I guess. And like, the first scenario that I talked about was like queerness as deprivation. But I think this is, I think I’m quoting writer Ocean Vuong. He said that, I think, queerness demands alternative innovation, and alternative ways of existing in the world. And I think that in in a bunch of pop culture space does represent that, and I think queerness… that metaphor intersects pretty well.

Tessa 45:56
Yeah, that is a fantastic answer.

Charles 45:58
That’s beautiful.

[interstitial] Well, fantastic. So I… Fayth, t’s been wonderful having you on. It’s been a real treat.

Fayth 46:18
Yeah, it’s been great. It’s been amazing, has been so good having someone else to appreciate the highly niche, yet extremely general brand of science that I do.

Charles 46:32
That’s what we’re all about. [laughs] Extremely niche, and yet also something very general. So, Fayth, if people want to find out more about you or your work online, where should they look?

Fayth 47:10
It’s just @faythtan on Twitter. Um, that’s Fayth with a y. And I think I’ve linked my personal website, anyway. Yeah. It’s mostly it’s mostly just my Twitter. I’ll talk about any forthcoming work, probably talk about my pre-print when it becomes a real publication at some point. Um, yeah.

Charles 47:33
Wonderful. I’m on Twitter @cockroacharles, and Tessa?

Tessa 47:38
I am on Twitter @spacermase.

Charles 47:42
The show is on twitter @ASABpod or at our website, where we post show notes and transcripts for every episode, asabpodcast.com. And if you like the show, please tell other people you think might also like it about it, because that’s how people listen to podcasts.

Tessa 48:12
Until next time, keep on sciencing.

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