New research shows that queens produce a striking ‘insulin blocker’, which dramatically slows down their aging process.
In the animal kingdom, it usually works like this: the more offspring you have, the shorter you live. Ants, however, are a notable exception to that rule. The queens—the only ants in a nest to reproduce—live in most cases five, ten, or sometimes even thirty times longer than their genetically identical worker sisters. How is that possible?
Battle for the throne
To understand how the reproductive queen lives much longer than her non-reproducing workers, researchers studied the ant species Harpegnathos saltator. In most species, ants are born as workers or as queens, but in this species, the ants often fight it out. When the queen dies, the remaining workers duel to decide who will be the next pseudo-queen. Then the brain of the winner transforms, causing the insect to adopt ‘queen behavior’.
What is particularly striking is that the life expectancy of this newly appointed queen suddenly increases considerably: from seven months to four years. But, surprisingly enough, this process is also reversible, if the ants encounter a real queen. In that case, the pseudo-queen stops laying eggs, and her life expectancy drops again to seven months. This striking phenomenon in Harpegnathos saltator ants gave researchers in the new study the perfect opportunity to study how to apparently turn the “knob” that regulates lifespan.
..DID YOU KNOW…
.The queen of the road ant can lay a million eggs and live up to 30 years? And that while its workers have a life expectancy of no longer than one year.
To unravel the secret of queen ants, the researchers studied the role of insulin in particular. Insulin is a hormone that helps convert food into energy. It plays an important role in metabolism, but also in aging. This is usually how it works with animals. When animals reproduce, it takes a lot of energy. For example, producing eggs is very energy-intensive and requires extra food, which in turn increases insulin levels. But this increased insulin level leads to faster aging and thus a shorter lifespan in most animals.
Back to the Harpegnathos saltator ants. The team found that after the pseudo-queen took over the throne, she suddenly produced a lot more insulin. That in itself is not very strange. “It’s very simple,” said researcher Hua Yan. “The pseudo-queen is reproductive, so she needs insulin. The funny thing is that insulin normally shortens lifespan. However, this is not the case with ants; the queen lives much longer than her workers.”
The researcher argued that ‘there must be something about the ants’ insulin signaling that differentially regulates reproduction and lifespan.’ And when the team searched further, they found something remarkable. The elevated insulin level in the pseudo-queen induces ovarian development as expected. But surprisingly, they then start to produce an insulin-suppressing protein called Imp-L2. This ‘insulin blocker’ slows down only one branch of the insulin pathway, the part normally responsible for speeding up the aging process. At the same time, it leaves the other branch, the reproductive side, intact. Basically, this insulin blocker allows ants to lay a lot of eggs without shortening their lifespan.
It means queen ants pull off a clever trick that can slow down the aging process and in some cases extend their own lifespan by a factor of thirty. “Hopefully this discovery will allow us to better understand the aging process in many more animals,” Yan said. Whether mammals, including humans, will one day be able to copy the trick from the ants – and thus inhibit the aging process by means of a similar insulin blocker? Time will tell.