Organizer of body axes: 600 million years old molecular principles
In humans and in animals, the correct position of tissues, organs and appendages is essential. Two body axes (the head-tail and the back-belly axes) usually define this position by generating a coordinate system, which supplies each cell in the body with its precise address. Thus, for example, the vertebrate central nervous system is always located on the back, and the intestinal tract on the belly of the animal.
|Transplantation of the fragment of the blastoporal organizer induces formation of an additional |
body axis [Credit: Copyright: Modified by Kraus et al., 2016, University of Vienna]
The organizer tissue instructs the surrounding cells to take part in body axes development, enforcing a certain developmental fate on them. Without an organizer, the embryo would not know where the head, the tail, the back and the belly should be. Mistakes in the regulation of body axes can lead to severe developmental defects, for example to the formation of Siamese twins.
In the last 25 years, the researchers largely elucidated the genetic underpinnings of this very particular part of the vertebrate embryo. The widespread assumption was that the organizer was a specific vertebrate feature, since it was not readily observable in insect or worm embryos.
"By performing transplantation experiments and molecular analyses we have found a blastoporal organizer in the embryos of the sea anemone Nematostella vectensis. For inducing axes, it uses the same class of signaling molecules as the vertebrate organizer," explains Technau.
"We conclude that this principle of the regulation of the embryonic axes existed already in the common ancestor of vertebrates and sea anemones more than 600 million years ago."
The findings are published in Nature Communications.
Source: University of Vienna [June 01, 2016]