A study led by University of California, San Diego biologists suggests that, contrary to the prevailing view, the process in early development that partitions the nervous system in fruit flies and vertebrates, like humans, evolved from a common ancestor.
In the September 12 issue of the journal Public Library of Science Biology, the researchers report that in both fruit fly and chick embryos proteins called BMPs play similar roles in telling cells in the early embryo to switch certain genes on and off, specifying the identity of the cells making up the three primary subdivisions of the central nervous system. The findings suggest a unified model of early neural development in which at least part of the mechanism for creating neural patterning has been preserved from a shared ancestral organism that lived over 500 million years ago.
"We have provided the first evidence for a common role of BMPs in establishing the pattern of gene expression along the dorsal-ventral axis of the nervous system of vertebrates and invertebrates," said Ethan Bier, a professor of biology at UCSD and senior author on the study. "Our results suggest that this process has been conserved from a common ancestor rather than evolving separately as had been previously believed."
Early in the development of a complex organism, when it is a ball of indistinguishable cells, BMP gradients are responsible for partitioning embryos into neural and non-neural tissue. During this phase, often referred to as neural induction, high levels of BMPs in non-neural regions actively suppress neural development. This role of BMPs is one of the best examples of a conserved evolutionary process.
However, it has been less clear whether BMPs also play a common role in further subdividing the nerve tissue into three distinct regions. Although the so-called neural identity genes get switched on in a similar pattern in relation to the BMP source, it has been speculated that disti
Contact: Sherry Seethaler
University of California - San Diego