To understand how snakes evolved their infrared detection systems, a group of scientists led by Prof. David Julius at the University of California, San Francisco, searched for potential infrared-sensing proteins in the western diamondback rattlesnake. They looked in particular at genes active in the nerve cells that are connected to the pits, called trigeminal neurons.
They found one gene, known as TRPA1, that was 400-fold more active in rattlesnake trigeminal neurons than in other kinds of neurons. Moreover, they found that the TRPA1 gene was not highly active in the trigeminal neurons of snakes lacking pits. These two pieces of evidence suggested that TRPA1 might encode a protein involved in infrared sensing.
The TRPA1 protein was very familiar to the scientists. A few years earlier, Dr. Julius’s group had identified TRPA1 as the receptor that drives our response to the molecules that give wasabi its punch, as well as to other chemical irritants, like tear gas.
View the original article here: As genes learn tricks, animal lifestyles evolve