The semen analysis can reveal the legacy of traumatic experiences: the pain associated with childhood stress is one of those environmental factors that can chemically modify the sperm, and have consequences on the health and behavior of children to come.

In legacy. So far this transgenerational passage through the male sex cells had only been documented in mice; Now a study raises the possibility that it will happen the same in humans. The level of two types of microRNA proved visibly upset in men who had experienced dramatic experiences during childhood; the same has been observed in mice, for which they have been proven detrimental effects "waterfall" on offspring.

MicroRNAs are small pieces of RNA that negatively regulate gene expression interfere, that is, with "normal" RNA and prevent the information that they bear from being translated into proteins. Participants therefore the genesis of pathological processes because they change the fate and function of cells, and are involved in processes of proliferation or cell death.

Past studies have shown that some habits or experiences of fathers (or grandparents) will leave its mark on the health of children: for example, fathers who smoke tend to have more fat children and grandchildren of those who have suffered from hunger tend to be more long-lived . These studies, however, are controversial in some respects: it is unclear how these environmental factors can have an influence so pervasive and lasting.

Tough questions. One possibility is that the transmission takes place through the microRNA, able to intervene on the work of genes. Larry Feig at Tufts University, Massachusetts, has asked 28 male donor of a fertility clinic to complete a questionnaire for the evaluation of childhood trauma of varying degrees, from physical and verbal abuse, until the emotional neglect or family problems. Who includes four or more factors of deep stress in the past is more prone to develop health problems such as heart disease or depression.

A measure objectively. The sperm of men with four or more indicators contained smaller amounts of two kinds of microRNA, whose exact function is not known - but that would have an important role in the development in utero. This is the first experimental verification of the fact that stress can change the male sex cells. The two microRNA in question are not in the egg: the maternal gene pool can not therefore "offset" this reduction. Studies on mice have shown that this decrease in sperm also drag the children, and so on - remain as a brand for generations.

The results are especially important for screening procedures, for example in the military: those who lived through bad experiences as a child is more at risk of developing a disorder of post-traumatic stress.

From Focus