Fruit flies are desexualized when they age. The male brain gets masculinized more than the female brain due to age related changes. The conclusion of a study was done at Linkping University. The findings are in a journal.
Weak people can't afford to invest in sexual behaviors the same way as healthy people. It is not known if aging leads to a reduced investment in sexual activity. For individuals close to the end of their lives, going all in on reproduction, in order to pass on their genes before it is too late, would be a good idea. Sexual behaviors are directed from the brain, and to find out what happens to sex differences in this tissue when fruit flies age, the researchers have investigated how genes expressed to different degrees change over time.
The study shows that both sexes contribute to the pattern of gene expression in the brain.
The study shows that if the expression of a certain gene is higher in the brains of young females than in young males, the expression is reduced in older females and increased in old males.
The results show that the changes are bigger in males than in females.
The connection between investment in sexual traits and reproductive success is not as strong in females as it is in males. A female fruit fly only needs to decide how much energy she has available for reproduction if she wants to reproduce. The cost of increased investment is higher for males than for females because of stiff competition, even though aging implies less resources are available to invest in reproduction and other activities for both genders.
"If you keep investing as much as before in reproduction when you get old, you don't have energy left for survival," says Urban Friberg, who is senior associate professor at the Department of Physics, Chemistry and Biology.
Results from studies on other animals that have focused on age related changes in genes in one sex have the same result. Fruit flies show results that may be applicable to many other animals.
"We get the same general results in both the populations of fruit flies that we have examined, even if they differ quite a bit with respect to which genes are involved."
The results of the study are similar to the ones obtained by the group. Sex differences in genes were compared between male and female flies. The earlier study showed that male and female flies have the same genes, but males change their genes more than females.
There is no answer to what the signals associated with aging are. If the signaling molecule turns out to be shared with other species, it could be rewarding.
More information: Ageing desexualizes the Drosophila brain transcriptome, Proceedings of the Royal Society B: Biological Sciences (2022). DOI: 10.1098/rspb.2022.1115. rspb.royalsocietypublishing.or … .1098/rspb.2022.1115 Journal information: Proceedings of the Royal Society B
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