A novel technique by Cornell University researchers has revealed that seminal fluid protein transferred from male fruit flies to females during mating alters the expression of genes related to the fly’s circadian clock.
The finding, published in the Proceedings of the National Academy of Sciencesmight help explain how this protein, called a sex peptide, alters female behavior.
Post-mating, sex peptide has been shown to cause increased egg-laying, aggression, activity and feeding, while reducing sleep and mating interest in males. previously unmated females.
“Flies like to eat at certain times of the day,” said Mariana Wolfner, a professor of molecular biology and genetics and one of the paper’s lead authors. “They sleep at certain times and the circadian clock machinery controls when the flies are likely to do these things.
“What we see,” she said, “is that these same behaviors – like sleeping and eating – are altered following mating by the sex peptide. One way to do this is to basically move the entire fly clock.”
The startling findings were made possible by examining transcriptomes – the RNA sequencing that reveals gene expression, or which genes are turned on and off – at many different times, providing high-resolution data that sheds light on order. in which the changes occur.
During the first four hours following mating, the researchers found changes in the expression of genes involved in the female fly’s metabolism and in the circadian clock. It is unknown what triggered these initial changes, but pheromones or seminal fluid proteins other than the sex peptide are possible candidates. Initial effects were short-term; they didn’t last without sex peptide and seemed to prime the system.
In a second phase, four hours following mating, the researchers found that the sex peptide caused changes in genes that regulate circadian rhythms and genes that are regulated by circadian clock pathways.
The study opens the door to future work that explores questions such as: how long does the effect last and whether these effects occur in other organisms, given that circadian clock genes are highly conserved in many forms of life.
