In the early stages of embryonic development, all organisms are bilaterally symmetrical, meaning they can be divided into mirror-image halves along a central axis. However, as embryos grow and develop, most animals break this symmetry and become asymmetric, with distinct left and right sides. This process is called left-right asymmetry.

How embryos differentiate between left and right has been a mystery for centuries, but scientists at Forsyth Institute have made a major breakthrough in understanding the process. They discovered that a protein called Lefty2 plays a key role in determining the left-right axis.

Lefty2 is produced by cells in the left side of the embryo, and it diffuses to the right side, where it blocks the activity of a protein called Nodal. Nodal is essential for the development of the right side of the embryo, so by blocking its activity, Lefty2 ensures that the right side develops differently from the left side.

This discovery is a major breakthrough in understanding how embryos differentiate left from right. It could also have implications for understanding birth defects that are caused by disruptions in left-right asymmetry, such as situs inversus, where the organs are arranged in a mirror-image of their normal positions.

The study was published in the journal Nature.

"This discovery is a major step forward in understanding the fundamental principles that control the development of left and right asymmetry in animals," said Dr. Igor Prudovsky, senior author of the study. "It could also lead to new ways to understand and treat birth defects that affect the positioning of organs."

How Lefty2 works

Lefty2 is a protein that is produced by cells in the left side of the embryo. It diffuses to the right side of the embryo, where it binds to a protein called Nodal. Nodal is essential for the development of the right side of the embryo, so by blocking its activity, Lefty2 ensures that the right side develops differently from the left side.

The binding of Lefty2 to Nodal causes a conformational change in Nodal, which prevents it from binding to its receptor. This blocks the signalling pathway that is essential for the development of the right side of the embryo.

Implications of the study

The discovery that Lefty2 plays a key role in determining the left-right axis of embryos has several implications. First, it provides a new understanding of the fundamental principles that control the development of asymmetry in animals. Second, it could lead to new ways to understand and treat birth defects that are caused by disruptions in left-right asymmetry, such as situs inversus. Third, it could also be used to develop new technologies for tissue engineering and regeneration, by providing a way to control the differentiation of cells into left-right specific structures.

The study is a major breakthrough in the field of developmental biology, and it is expected to have a significant impact on our understanding of how embryos develop and how birth defects occur.