Telegony of flies

Scientists have discovered a biological similarity of telegony during experiments on flies

Alexander Telishev, "Russian Planet"

Australian biologists have found out that in living nature there is still a kind of similarity of the so–called telegony - a popular concept in the XIX century, whose supporters believed that all previous sexual partners with whom a woman had sex before conceiving a child transmit their signs to her offspring from another man. The Australian University of New South Wales tells about the results of experiments on nereid flies published in the journal Ecology Letters (Angela J. Crean, Anna M. Kopps and Russell Bonduriansky, Revisiting telegony: offspring inherit an acquired characteristic of their mother's previous mate).

Nereid flies. Photo: Russell Bonduriansky

"We know that those traits that are often found in members of the same families depend not only on variations in genes that are transmitted from parents to children. Many mechanisms of non-genetic inheritance of traits allow various factors of the environment in which expectant mothers and fathers live to influence the appearance of the child. Our new discovery takes all this to a new level – we have shown that a male can pass on some of his traits to the offspring of several other individuals of the stronger sex. Of course, we don't know yet if something similar exists among representatives of other species," says Angela Crean from the University of New South Wales in Melbourne (Semen secrets: how a previous sexual partner can influence another male’s offspring).

Crean and her colleagues in the laboratory, Russell Bonduryansky and Anna Kopps, made this amazing discovery by experimenting with nereid flies (Telostylinus angusticollis) - unusual insects that live in areas of Australia where a variable climate prevails. In this part of the continent, periods of relative abundance are often replaced by prolonged and severe droughts.

As long–term observations of the life of nereids have shown, they have developed an unusual strategy to combat such changes - these insects transmit information about the current environmental conditions to their descendants using special epigenetic tags, chemical changes in the structure of proteins enveloping the DNA molecule. Such modifications change the activity of genes, making them less or more readable, which allows parents to "tune" the body of their future children to live in the current conditions.

During field expeditions, Krin, Kopps and Bonduryansky noticed that the offspring of some females were not always similar in size, appearance and other characteristics to their supposed father. This observation, as well as the fact that nereid flies mate with dozens of partners during the breeding season, prompted the authors of the article to think that some other non-genetic processes besides epigenetics could be involved in this case. At this moment, scientists remembered the existence of telegony, even in the partial justice of which all biologists stopped believing at the beginning of the XX century.

This idea has deep historical roots – for the first time, Aristotle spoke about the possibility of children inheriting the qualities of their mother's previous sexual partners. In the XIX century, this idea was developed and framed in the form of a scientific concept by the famous Austrian biologist August Weisman and many other scientists due to the erroneous interpretation of experiments on crossing and hybridization of animals. When biologists discovered the basics of genetics at the beginning of the XX century, it became clear to them that telegony could not exist in principle, since it was not compatible with classical Mendelian genetics. Today, after the discovery of epigenetics and other non-genetic inheritance mechanisms, such categorical statements are often questioned.

Guided by this idea, the authors of the article decided to follow the process of reproduction of nereid flies in their laboratory and create several unusual situations with which they checked whether telegony, in any limited form, actually exists.

During these experiments, scientists noticed that insect sperm contains not only genetic material, but also a small amount of proteins and other nutrients. According to biologists today, the female's body uses them to make up for the losses in energy that the expectant mother spends on growing eggs, as well as on finding and forming a clutch. The composition and "density" of this nutritious cocktail is not constant, and it depends on the health and the conditions in which the male lived.

For this reason, Krin and her colleagues suggested that seminal fluid can indirectly control the work of genes, forcing the mother's body to "rewrite" part of the epigenetic labels in the eggs immediately after sexual contact. They tested this hypothesis by raising two groups of male flies, one of which was extremely limited in access to food. The size of the nereids directly depends on the availability of food in the larval stage, thanks to which scientists obtained two sets of very large and very small insects.

When their wards reached puberty, biologists placed the flies in a vessel with females who managed to live only a week after leaving the pupal state. These young insects already have full-fledged sexual organs, but at the same time their eggs are not yet ready for fertilization, which gave scientists the opportunity to track how seminal fluid can affect the work of genes in eggs without fear of accidentally fertilizing them.

A few days after the first mating session, the authors of the article once again let the males into a container with flies that had already reached puberty by that time. At the same time, if for the first time a female had sex with a "fat" insect, then Krin and her colleagues let only small males into her jar, and vice versa.

The offspring of these insects, according to the authors of the article, confirmed their suspicions. The children of the flies, whose first partners were "skinny" males, remained small throughout their lives, despite the abundance of food during their growth. Similarly, mating with a large representative of the stronger sex before puberty led to the fact that all their offspring differed in large sizes.

"We found that although the second male was the biological father of these flies, their size depended on what their previous partner ate at the time when he was a larva. Our discovery significantly complicates all our ideas about how different variations and distinctive features are transmitted between generations. As always, at the moment when we think that we have managed to uncover all the secrets of nature, she performs another trick and throws up a new riddle, showing that we still have a lot of new things to learn," concludes Krin.

Portal "Eternal youth" http://vechnayamolodost.ru 02.10.2014