PASADENA, Calif.For all animals, development begins with the embryo. It is here that uniform cells divide and diversify, and blueprints are laid for future structures, like skeletal and digestive systems. Although biologists have known for some time that signaling processesmessages that tell a cell to express certain genes so as to become certain parts of these structuresexist at this stage, there has not been a clear framework explanation of how it all comes together.
Now, a research team at the California Institute of Technology (Caltech) has outlined exactly how specific sets of cells in sea-urchin embryos differentiate to become the endoderm, the early domain of the embryo that eventually forms the gut. Their findings were reported in a paper entitled "A gene regulatory network controlling the embryonic specification of endoderm," published by the journal Nature online on May 29, in advance of the print version.
"If you only look at the genetic information of cells in an embryo, they all have the same genome and they all start from the single-cell zygote," says Isabelle S. Peter, a senior postdoctoral scholar at Caltech and coauthor of the study. "But then cells start to divide and, at some point, these cells are no longer identical in the genes that they express. We wanted to know how this process is achievedhow differences are established in cells in the right place and at the right time."
In order for undifferentiated cells to change their state and become a specific part of the body, the right genes need to be expressed, and the wrong ones repressed. The most important genes are regulatory genes, which control the expression of other genes, and form a gene regulatory network (GRN) that doles out differentiation instructions by turning genes on or off at specific times during embryonic development.
In the work described in the Nature paper, Peter and Eric H. Davidson, the Norman Chandler Professor of
|Contact: Deborah Williams-Hedges|
California Institute of Technology