Ion channels and the astonishing defense of frogs and birds

At the beginning of each month, we get the chance to enjoy another seminar from the SGP EpIC Seminar Series. It’s a fantastic series organized by Jelena Baranovic, Osama Haraz, Conor McClenaghan, Lejla Zubcevic, and Gregory Malar, featuring great speakers and engaging, informative talks. Highly recommended for anyone interested in electrophysiology and ion channels.

This Tuesday, April 2, Fayal Abderemane from UCLA discussed toxins and ion channels, inspiring us to write this blog post.

When we think of toxins or venoms, snakes, scorpions, or spiders often come to mind. In one of our previous blogs, we’ve already explored snake alpha-neurotoxins and their paralyzing effects on nerve-muscle communication. Similar stories unfold with various scorpion and spider toxins, which frequently exert their toxic effects through modulation of voltage-gated sodium, calcium, or potassium channels.

Additionally, marine species like cone snails, with their conotoxins, and the infamous fugu fish and blue-ringed octopus, known for their tetrodotoxin, also come to mind.

However, Fayal Abderemane introduced us to two other species not typically associated with high toxicity: frogs and birds. Specifically, the Colombian golden poison frog (with the fittingly terrifying name Phyllobates terribilis) and the New Guinean songbird, the hooded pitohui.

It turns out these two beautiful creatures contain an extremely potent steroidal alkaloid called batrachotoxin, which facilitates the opening and prevents the inactivation of voltage-gated sodium channels. The golden poison frog contains so much of this toxin that even touching it can be dangerous. While the hooded pitohui birds seem to contain less batrachotoxin in their skin and feathers compared to the poison frog, touching them with bare hands can still cause numbness and a burning sensation.

Interestingly, neither the golden poison frog nor the hooded pitohui birds produce their toxins themselves. Instead, they acquire them in the wild from their diet, such as bacteria or insects. So, if kept in captivity without access to their natural diet, these species will be toxin-free.

Another fascinating fact is that the voltage-gated sodium channels of neither the golden poison frog nor the hooded pitohui are resistant to batrachotoxin. These species protect themselves from the acquired toxin with “toxin sponge” proteins that bind the toxins to impede target binding.

So, the next time you find yourself in New Guinea or Colombia, admiring the local wildlife, remember: those beautiful golden frogs and reddish-brown plumed birds are better admired from a distance.

And as tempting as it may be to bring back a unique surprise gift for your kids, resist the urge. After all, how are you going to present it to your child? “Here’s a frog, but don’t touch it, don’t look at it too long, and definitely don’t kiss it—no, it won’t turn into a prince.” ???

Maybe settle for a nice, non-toxic keychain or fridge magnet instead?