2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Scientists have found that male flies affect the behavior of females after mating, namely, improve their long-term memory. This involves a protein from their seminal fluid, which acts directly on the female's neurons, enhancing their activity. The research is published in the journal Science Advances.
Mating affects the physiology of the female from different angles: for example, it reduces the willingness to mate further or changes food preferences. Of course, it also affects behavior and cognitive abilities, but it is still not completely clear how.
On the one hand, there is a widespread belief that females of different species become stupid after fertilization, since energy resources from the brain are redirected to the fetus. On the other hand, it would be logical to assume that not all brain functions suffer during pregnancy, and some are beneficial for the expectant mother and, conversely, are strengthened. These functions may include, for example, spatial orientation, risk avoidance, and the ability to remember where food and water sources are.
A group of scientists from the Paris Institute of Sciences and Humanities Research led by Thomas Preat (Thomas Preat) tested the effect of mating on memory in fruit flies. Previously, researchers have already discovered that the effect of sperm on the body of flies is mediated by SP - seminal protein. Receptors for it are found in the uterus and nervous system of Drosophila, but their functions - especially in the nervous system - are still unclear.
Scientists conducted a standard avoidance experiment on flies: they were offered a certain smell, which was accompanied by an electric shock. Then the flies were asked to choose between the branches of the labyrinth, one of which contained a smell-stimulus, and the other did not smell of anything.
After mating, flies performed twice as well at this task than flies that did not mate with males. But those who were crossed with mutant males, whose sperm was devoid of SP, showed the same result as unmated females. The researchers then tried replacing mating with SP injection. Females who did not contact males, but received an injection, passed the maze as well (p = 0, 004) as females after mating.
To test exactly how the SP protein acts on memory, the researchers blocked the SP receptor in neurons in the uterine wall. But nothing has changed: the flies still successfully (p = 0, 009) passed the maze after mating. Then the scientists suggested that SP can affect the work of serotonergic neurons - it is known that their activity is associated with memory in flies. Indeed, SP receptors have been found on neurons in the abdominal nerve cord and brain of Drosophila.
The work of serotonergic neurons in flies is regulated by the enzyme phosphodiesterase. Scientists measured its activity and found that after mating, it is half that of non-mating flies - that is, it allows neurons to be more active. When her work was blocked, the flies that did not contact the males began to pass the maze as well (p = 0, 003) as the females did after mating.
The authors of the work believe that a good memory for smells can have an important adaptive value for pregnant flies - for example, it allows them to carefully choose a place for laying, so that there is no enemy or any poisonous substance nearby.
Scientists have previously discovered unusual properties in sperm from different organisms. For example, human seminal fluid suppresses inflammation in the female genital tract and makes pregnancy easier. The bee sperm blinds the queens so that they do not leave the hive and mate with other males. And the age of sperm in zebrafish fish determines the health and longevity of the offspring.