For the first time, many researchers have documented a living organism through a liquid phase during its development. In the journal Nature Cell Biology, a group of scientists led by Carl -Philipp Heisenberg of the institution of Science and Technology, Austria shows that cell within the embryonic Zebrafish turn temporary into liquid as the embryo grows.
According to the lead author Nicoletta Petridou “Such a fluidity transition was predicted to happen by theory and models, but here we show for the first time that it happens in a real, living organism”.
A yolk of Zebrafish eggs is covered with blastoderm, a thin layer of tissue. As the egg develops, the blastoderm forms a dome. By testing the tissue throughout the development of the embryo, the team find that “doming” the tissue at its center suddenly become a fluid.
Many researchers explain that fluidity occurs when cell divide rapidly. Cell are normally connected to their neighbour, but during this phase of massive change, they effectively become free floating.
In the studies, Heisenberg and his team determined fluidity by testing the rate of tissue deformation under pressure. More viscous tissue deforms less quickly than liquid.
Petridou says “Non-canonical Wnt signaling keeps cells connected and allows the embryo margins to bypass fluidisation.”
“We think that the default of the tissue is to become fluid, but the signals keep areas from turning fluid.”
Researcher said that they might have found the first known instance of phase transition - a concept in physics that describes a change in a structure of matter, as when water from a frozen solid into a liquid and then into a vapour - in organisms.
“However, we are working further to define whether this is a phase transition. Phase transition can happen in molecular networks but we don’t know that it will happen in tissue or embryo.”
By: Lakshender S Angras