Now Northwestern University scientists propose a new model for how neural crest cells, and thus vertebrates, arose more than 500 million years ago.
The study also turns conventional thought on its head. Previously, scientists thought neural crest cells had to evolve to gain their incredible properties, but the Northwestern work shows the power was there all along. Researchers now can focus on the molecular mechanisms by which neural crest cells escaped having their potential restricted.
If the neural crest cells did not have to evolve, but rather the “incredible properties” were there all along, is that not an argument for design in nature?
Not that we can expect the researchers to make such an argument. They have bills to pay and families to feed, and Darwin’s followers prowl constantly.
In a study using embryos from the frog Xenopus, a powerful model system used in studies of development, LaBonne and her team found that neural crest cells and the early pluripotent cells present in blastula embryos have surprising similarities, including shared expression of a key set of genes which work together to endow the cells with their unique properties.
“Neural crest cells never had their potential restricted at all,” LaBonne said. “We believe a small population of early stem cells were set aside, so that when the time came, their immense developmental potential could be unleashed to create new features characteristic of vertebrates.”
The study underscores just how much remains to be discovered about embryonic development. The human body has more than 10 trillion cells elaborately organized into tissues and organs that are intricate and highly complex, yet it all is self-assembled from a single cell, the fertilized egg.
“It’s a fascinating process,” LaBonne said. “One of the great frontiers in biology is understanding both how complexity is generated and how it evolves to create what Charles Darwin memorably called ‘endless forms most beautiful.'”
Ah yes. The serious scientist attempts to protect herself from Darwin’s thugs by ending with a hymn of praise to the Sage of Down. Will they be fooled? Oh maybe. Many are dumb enough now. Darwin’s sages are not recruiting the brightest lights* any more.
* See, for example, Darwin-in-the-schools lobbyist Zack Kopplin thinks he’s currently losing … Blames right wing Christians. No further insights.
Here’s the abstract:
Neural crest cells, unique to vertebrates, arise in the ectoderm but can generate cell types typically categorized as mesodermal. This broad developmental potential persists past the time when most ectoderm-derived cells become lineage restricted. The ability of neural crest to contribute mesodermal derivatives to the bauplan has raised questions about how this apparent gain in potential is achieved. Here we describe shared molecular underpinnings of potency in neural crest and blastula cells. We show that in Xenopus, key neural crest regulatory factors are also expressed in blastula animal pole cells and promote pluripotency in both cell types. We suggest that neural crest cells may have evolved as a consequence of a subset of blastula cells retaining activity of the regulatory network underlying pluripotency. (paywall) – Elsy Buitrago-Delgado, Kara Nordin, Anjali Rao, Lauren Geary, and Carole LaBonne. Shared Regulatory Programs Suggest Retention of Blastula-Stage Potential in Neural Crest Cells. Science, April 2015 DOI: 10.1126/science.aaa3655