The Backbone of Proper Development

The formation of the back and belly is a milestone for frogs as well as for humans and other vertebrates.  It occurs at the beginning of the process of gastrulation, during which the front and back, head and tail, left and right are established, creating the first appearance of a recognizable body plan. If this step fails, the embryo will eventually die.

"Gastrulation and the process of defining your back-belly axis is such an important step that you actually have multiple proteins being expressed there, just in case one of them fails, the others can compensate," said lead author and UC Berkeley post-doctoral fellow Mustafa Khokha.  "Redundancy is designed to make the embryo robust, so as to avoid birth defects."

Khokha and his colleagues at UC Berkeley were able to block three of the five factors at once, and this time found dramatic changes in the embryo.

"When we removed these signals, all the tissues that form on the back of the embryo - brain, spinal cord and muscles - were lost," Khokha said. "Not only were back tissues lost, but belly tissues were greatly expanded - the whole embryo became re-patterned, so it's more belly-like than it is back-like. So, these signals are necessary for the pattern to occur properly."

The discovery was reported this month in the journal Developmental Cell.