Get out of my hair, Dedie.
What’s up guys? How’s it going? Have you been well? I have a very important question for you. Have you seen the new Deadpool movie yet? If you haven’t, and you’re old enough, then why haven’t you? It’s got everything. It’s got action, romance, and naked Ryan Reynolds fight scene. Um, it also has science, sort of. Deadpool’s main superpower, apart from being hilariously witty and meta is regeneration from being injected with a serum that mutates the cells. And whilst mutation serum is the stuff of science fiction, regeneration actually happens to this very day. Which leads me to the question, have you ever wondered how Deadpool regenerates? Well, I’m gonna spell it out for you.
Humans have the ability to regenerate to a certain degree, like my skin growing back after a papercut, and my liver growing back after a few bevies. But cut off an arm and it won’t grow back. We’ve lost the ability to regenerate through evolution. But some animals can grow back entire limbs like starfish and salamanders. And we can even trick them into growing back new ones like this axolotl with an extra leg. Look how happy his little face is. Other animals can partly regenerate, like mice if you cut off their fingertips, but don’t actually cut off their fingertips, and some lizards who can detach the tails as a way of escaping predators, or this kid, and then growing back a new one. But why would lizard regeneration help us understand how good old Dedie regenerates more than salamanders.
Lizards, as well as other reptiles, birds and mammals are amniotes meaning that during development, the embryo is kept in the set of protective membranes. And this makes them more closely related to humans and other animals that can regenerate like newts and salamanders. So by understanding the mechanisms that they use, we can target the pathways in human cells in order to regenerate damaged tissues. How cool is that? So how do lizards regenerate their tails?
Well, there’s been two ways that’ve been identified. The first one is called epimorphic regeneration, which is found in salamanders, and has been studied in E. macularius, more commonly known as the leopard gecko. When the tail is detached or cut off, the skin of the gecko grows over the stump, and forms a layer called the wound epidermis. This then activates the formation of the blastoma underneath, which is a group of cells made up of mature tissue and muscle cells, reverting back to their immature state. These T-differentiated cells are a lot like stem cells, as they can turn into a few different types of cell. But they also have a memory of what they used to be, which stops them from sending into any type of cell and tells them what pathway to go down. In other words, they’re Lineage Restricted. Once these T-differentiated cells leave the blastoma, they stream down the tailstock and then turn back into mature cells. And they keep on doing this until a new tail is made.
The second way of lizard tail regeneration has been studied in the green anole lizard, A. carolinensis. And instead of having a group of regenerating cells at the end of the tailstock, like in the leopard gecko, multiple sites of growing cells have been found through the regenerating tail. It’s not known where these cells come from. But T-differentiated cells like in the blastoma have been ruled out. And whilst lots of pathways have been studied throughout this process, like muscle nerve regeneration, and wound in immune responses, there’s still a lot of things that we don’t know. Like why the blastoma doesn’t form if the wound epidermis formation stopped? Or how the regenerating cells know where to go through the regenerating tail in the first place? We just don’t know yet. But we do know that the evolution of these mechanisms of tail regeneration has an effect on the time it takes for the tail to grow back. If it has enough nutrients, it takes the A. carolinensis 60 days to grow back its tail, whilst the E. macularius only needs 30. And again, we just don’t know why.
And for the lizard, the power of regeneration comes with a small catch. Whilst it may look the same, the regenerated tail has a distinctly different skeletal and muscle structure. And this means that it is less flexible, and not an exact copy of the original. But it is something. So there you have it, clear scientific proof that Deadpool may actually be part lizard. Tough luck, mate.
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