Just a handful of toxins make up the tiger rattlesnake's potent substance, which attacks the nervous system of its victims, scientists reported on January 18 in Proceedings of the National Academy of Sciences.
When the researchers sequenced the tiger rattlesnake’s genome, they found that only about half of the venom-related genes it possessed were actually being used. Understanding this could lead to a better understanding of the ultra-dangerous venom, which in turn could lead to improvements in medicines derived from snake venom, they say.
“[They] are like meat tenderizer; they basically digest your flesh, your cells,” says Christopher Parkinson, an evolutionary biologist at Clemson University and another coauthor of the findings. In many rattlesnakes such as the western diamondback, he says, “The venom is potent, but it doesn’t have the lethality of a tiger rattlesnake’s venom.”
The tiger rattlesnake possessed 51 genes thought to be related to venom production. For comparison, the prairie rattlesnake has 92 and the king cobra has 232. However, many of those paltry 51 genes contained in the tiger rattlesnake’s genome seemed to be dormant.
It’s possible that the tiger rattlesnake’s ancestors once possessed more complex venoms that became streamlined over time. Alternatively, neurotoxins could once have been more common among rattlesnake species, only to be lost through evolution.