The researchers compared the genome of common vampires (desmods) with 26 other bat species. It turned out that 13 different genes are absent or inactive in blood-fed mice. It was these changes that helped animals adapt to feeding on blood, geneticists say.
Vampire bats are the only mammals that feed exclusively on blood. To identify the changes that allowed animals to adapt to such a diet, scientists from the Max Planck Institute for Molecular Cell Biology and Genetics examined the genomes of 27 species of bats.
“We found the loss of 13 different genes, 10 of which were not previously known,” the scientists say. “These genetic changes reflect, for example, decreased insulin secretion, limited cellular storage of polysaccharides, the unique stomach physiology, and the ability of these animals’ immune systems to fight a large number of pathogens that are transmitted through the blood of prey.”
Blood is a complex diet for several reasons, scientists say. This is not the most high-calorie food source due to the high liquid content. Bats have to drink blood almost one and a half times their own weight in one meal. In order to adapt to such a diet, the bat stomach has evolved to be able to stretch and work primarily on fluid intake.
In addition, the blood contains a high iron content, and the main nutrients are proteins (about 93%). Genetic changes, scientists say, allow bats to quickly remove excess iron from the body. The share of fats and carbohydrates is about 1% for each of these substances. A small amount of carbohydrates consumed led to a decrease in the susceptibility of cells to insulin secretion, the same as in people with type 2 diabetes.
The stores of glycogen (polysaccharide) and fats in the body of desmods are also significantly reduced. This makes them vulnerable to prolonged starvation. Without food, these bats die in two to three days. To compensate for this vulnerability, bats have learned to socialize. Successful hunters share some of their prey with mice that are unlucky that day.
The scientists also noted that bats have “disabled” cone or daytime vision. These strictly nocturnal bats are most active during the darkest periods of the night and even avoid moonlight. In addition, in order to find their prey, vampire bats have developed additional sensory apparatus and developed the ability to perceive infrared radiation.