Happy Microbe Monday! I hope you are well. Personally I am very sleepy.

As always with animals, I tend to only really like the ones that have some kind of weird bacterial thing going on. So I wanted to talk about pufferfish and porcupinefish.

These little creatures are best known for being incredibly cute. They have big ol eyes and navigate around super slowly and are just little sweeties I love them. They are great at maneuvering but again, super slow, so they have a lot of defense mechanisms. The most well-known is puffing up in the throats of would be predators, which is I imagine a quite unpleasant experience for everyone involved.

Another found in some species is neurotoxin. Tetrodotoxin, or TTX. Many, many puffers and porcupinefish (among other related species) produce this neurotoxin and have large amounts in their skin and organs.

Well! I say they produce it, but as you might imagine, this is yet another of the manifold bacterial labors wont to go credited instead to their metazoan overlords. In fact, the toxins are produced by intestinal bacteria in almost all cases.

If you raise a pufferfish on a "non-toxic" diet with none of these TTX producing bacteria, they produce no TTX. It's entirely a diet-based thing. Puffers have a few means of immunity to TTX, mostly shared genetic mutations that help block it from messing with their nerves.

TTX is really funny because it is just profoundly turbolethal and found in silly, clumsy-looking little underwater guys because they eat stuff with even smaller silly little guys in it.

Basically, creatures with nervous systems need their nerves to communicate with each other to be useful. And you need those nerves doing that in order to do anything, even subconscious stuff like breathing. When those nerves are impaired, things get bad very rapidly.

Nerves communicate via action potentials. These work electrically; potassium and sodium ions work together essentially to depolarize and repolarize the nerve. This is a complex topic you could talk about for a while. The main thing of note is that there are voltage-gated sodium channels. These open when a neuron depolarizes. They let in and out a bunch of really important ions for the whole action potential process to work.

TTX binds to these voltage-gated sodium channels, essentially shutting down the whole nervous system in one fell swoop. TTX-resistant organisms tend to have mutations in these channels to prevent this. We are not TTX-resistant. It's like cutting all the wires at a power station. It causes shutdowns in every part of the body that needs these channels, most notably nerves but also muscles and a few other excitable cells. This absolutely rends your respiratory system and utterly paralyzes you.

Hehehe silly little orb shaped fish. Hehehehehehe little bacterias.

Thank you for reading and have a happy Microbe Monday! Don't eat pufferfish probably. I want you to keep posting.