Seahorses and their relatives in a needle fish who are carrying babies inside the body, discovered a complex of adaptations to pregnancy, similar to what happens in the body of pregnant women. It turned out that fish in the same way as in humans, reduced activity of some immune pathways. However, they came to this very different way: they not only alter gene expression, but also lost some genes entirely. A study published in the journal Proceedings of the National Academy of Sciences.
Pregnancy creates many problems for the parent body, and the energy cost is just one of them. Much harder to keep in balance the immune system, which sees the developing embryo as a foreign body. In mammals (including humans) there are several ways to suppress the immune system. For example, stem cells of the child can penetrate into the bone marrow of the mother and to quell the inflammatory activity. And the cells covering the placenta can hide the unusual proteins of a child from parental immunity.
Nevertheless, mammals are not the most comfortable object in order to find out which of these devices is the key. The fact that mammals have not survived the transitional forms between the external development of the young and pregnancy. At the same time, among vertebrates, the pregnancy has arisen independently more than a hundred times, and among them you can find a much more suitable object.
Olivia Roth (Olivia Roth) from the Center of the Helmholtz Oceanography in Kiel, together with colleagues focused on the family of a Needle fish (which include fish-needle and seahorses). Inside this collection you can find different types of paternity: some attach the eggs to their tummy on the outside, others defend their extra skin folds, and others carrying them in special pockets with the equivalent of the placenta. We already wrote about the fact that the molecular characteristics that can be considered a full-fledged male pregnancy, seahorses and even got special genesthat are responsible for the breakdown of shell eggs.