Royal Longevity
The ant queen lives a long time because it controls the level of insulin
Ekaterina Petrova, PCR.news
In most animals, reproduction correlates with a shorter life span: the more an individual leaves offspring, the shorter its life. However, it is different with eusocial insects: the reproductive female of ants lives much longer than workers. So, in jumping ants The Harpegnathos saltator uterus (aka the queen, aka the queen) lives for about five years, and the workers are only seven months old.
When the queen dies, the workers compete for the right to become a new reproductive female — they fight with each other.
The winning individual will not only be able to mate and lay eggs, but will also live five times longer than the others. If a new queen is planted in the colony, the pseudo-queen will again become a working individual, whose life expectancy will also become the same.
To find out why reproductive female ants live so long, a team of scientists from the United States compared the gene expression of a female ant, H.saltator, which became a pseudo-queen, before and after the caste change. They studied the genes in those organs that regulate the processes of metabolism, reproduction and life expectancy — in the brain, fat body and ovaries. Scientists also examined these tissues in worker ants.
It turned out that in worker ants who became reproductive females, the synthesis of insulin in the brain increases, and in the fat body — lipids and vitellogenin, which are needed for the formation of eggs. As a result, one of the two main branches of the insulin signaling pathway is activated — MARK (mitogen-activated protein kinase), which controls the metabolism and formation of eggs.
To make sure of this, scientists tried to inject insulin or its blocker to ants. Injections of insulin into the stomach of workers stimulated ovogenesis, but simultaneous injection of the MAPK U0126 pathway inhibitor blocked this effect.
When researchers prevented the phosphorylation of MAPK in pseudocorals using the same U0126 inhibitor, the expression of vitellogenin in the fat body decreased, and with it the number of oocytes.
Thus, an increased level of insulin in pseudocorals induces the development of ovaries. Follicular cells in the growing ovaries produce the hormone ecdysone, further enhancing the activity of MARK, oogenesis and reproduction. However, along with this, the ovaries begin to produce the Imp-L2 protein. This protein blocks the signaling of the second main branch of the insulin pathway — AKT/forkhead box O (FOXO) in the fat body (but not in the ovaries). These signals control aging, their increased activity leads to a reduction in life expectancy.
Thus, reproductive female ants need to increase insulin synthesis in order to produce eggs, but they simultaneously activate a mechanism that blocks the "side effects" of increased insulin levels — premature aging. Apparently, this compensatory mechanism works so well that the life of reproductive individuals becomes many times longer than the life of other ants.
"The two main branches of the insulin signaling pathway seem to regulate fertility and life expectancy in different ways, while increased signaling in one promotes reproduction in pseudocorals, and decreased signaling in the other leads to an increase in their life expectancy," said Danny Reinberg, one of the authors of the study, professor of biochemistry and molecular pharmacology at the Grossman School of Medicine at New York University.
The researchers hope that their discovery will allow them to better understand the mechanisms of aging. It is unclear whether it will ever be possible to prolong the life of mammals by partially blocking the insulin pathway. It is known that a diet that reduces insulin production can increase their life expectancy, but fertility suffers at the same time.
Article by Yan et al. Insulin signaling in the long-lived reproductive caste of ants is published in the journal Science.
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