By Michael Le. Semen says turn those genes on.
In many animals, seminal fluid alters both the bodies and sometimes even the behaviour of females. Human semen, too, triggers changes in the uterus, and might have wider effects on women, aimed at just one goal.
The effects are most striking in fruit flies: seminal fluid can make the females eat more, lay more eggs and be less receptive to other males. Now a team led by Tracey Chapman at the University of East Anglia in Norwich, UK, has found that male fruit flies selectively alter the chemical make-up of their seminal fluid.
In the presence of rivals, the males produce more seminal proteins. Females exposed to it show a wide range of changes in gene expression. Chapman thinks this kind of seminal alling is widespread in the animal world.
The semen of people, pigs and mice affects the female reproductive tract, and the question is whether it can also produce behavioural responses in female mammals similar to those seen in fruit flies. There have been claims that semen can do everything from making women sleepy after sex to strengthening the emotional bond with their partner.
One study, based on a survey of students, even found that women whose partners did not use condoms scored lower on a measure of depression. If that effect is real, depression in some people might be treatable with artificial-semen suppositories. Gordon Gallup of the State University of New York at Albany, who carried out the study, says a PhD student of his has replicated the finding in a survey of women, but the were never published. In flies, seminal proteins can directly affect behaviour because they enter the circulatory system, travelling throughout the body to the brain.
She has shown that seminal fluid induces expression of a range of genes in the cervix, including ones that affect the immune system, ovulation, the receptivity of the uterus lining to an embryo, and even the growth of the embryo itself. Her team is studying the effect of three microRNAs — RNA fragments that affect gene expression — released by the cervix in response to semen. Trending Latest Video Free.
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