Natural Poisons: A Protein Sponge Against Poison Dart Frog Poisoning

To the surprise of Minor’s team, however, this was not the case at all: painstakingly and carefully removed nerves along sodium channels from frogs were just as sensitive to neurotoxins in their experiments as other animals. A mutation that made rats’ sodium channels less sensitive in earlier experiments apparently had no effect on other animals: frog and bird neurons with mutated membrane proteins react to the toxin anyway; In addition, his nerves no longer worked as efficiently as in their natural form.

Obviously, poison dart frogs and pitohui birds defend themselves differently. One type of sponge mechanism comes into question, Minor and his colleagues suggest. Such protection is known from mussels, for example, which swirl in the paralyzing poison saxitoxin along with bacteria from their food. This venom also acts on sodium channels, but different animals can bind to it by a network of antitoxic saxophilin proteins and thus neutralize it. In theory, this poison dart would also work for frogs and birds, as further experiments showed: if the saxophilin protein was added, the animal’s stimulated nerves were protected from saxitoxin.

Minor and Company now suspect that poison dart frogs and pitohui birds have a similar venomous sponge against batracotoxins; However, they have not yet found a suitable sponge protein. However, experiments showed that the protection would work well. Amphibians such as bullfrogs produce saxophilin – apparently to protect themselves from saxitoxins. It is therefore quite conceivable that protection against frog and bird venom may be found in antitoxic capture proteins from the frog and bird itself. Furthermore, this type of self-protection may be more widespread than previously thought.