How vampire bats home in on hot veins

Garlic is well known to repel vampires, but scientists have discovered that the sensor that picks up the spicy ingredient in chilli is what attracts blood-thirsty bats to the juciest veins.

In common with some species of snakes, vampire bats appear to be drawn towards warm areas, which indicate a rich blood supply. Snakes aim for these hotspots to ensure their venoms act quickly and they do it by using special infrared-sensing nerves on their faces.

Now, writing in Nature, UCSF researcher David Julius and his colleagues have discovered that vampire bats use a similar technique.

Ingeniously, in just a small population of nerves supplying a series of "pit organs" around their noses, the animals produce a shortened version of a gene called TRPV1, which normally enables nerve cells to detect burning sensations when temperatures exceed 43°C. It is also activated by the chemical capsaicin, found in chilli, thus explaining why curry tastes "hot". But the shortened form of the gene makes cells sensitive to temperatures as low as 30°C and above, making it ideal as an infrared sensor to help the animals to home in on hot blood vessels.

The research also has important medical implications. Understanding how these pain-sensing receptors work, and how alterations to their structure can change their function and activity could lead to better painkillers in future, assuming the vampire bats haven't finished us off beforehand...