Every cell in an animal's body carries the same DNA. Yet this single genetic blueprint somehow produces neurons that fire, muscles that contract, and tissues that perform completely different functions. How identical genomes lead to such diversity remains one of the central mysteries of biology.
New research indicates that gene regulation (not just genes) is key to how different cell types arise from a single genome. By analyzing the ancient sea anemone cell by cell, the researchers built a detailed map linking DNA controls to the formation of different cell types. This is reported in Ecology of nature and evolutionThe work suggests that the regulatory framework underlying animal cell diversity was established early in evolutionary history.
“Expression tells us what cells do, and regulatory DNA tells us where they come from, how they develop, and which germ layer they come from,” said Dr. Marta Iglesias, co-author of the study, in her paper. press release.
The Roots of Cellular Diversity
Differences between cell types depend on how genes are controlled, not on the genes themselves. However, most of what we understand about this process comes from a small number of well-studied species, so its deeper evolutionary origins remain unclear.
To figure out this origin, researchers turned to the asterisk. sea anemone. Sea anemones, along with jellyfish and corals, belong to cnidarians, one of the earliest groups of animals that appeared about half a billion years ago. Despite their ancient origins, cnidarians possess specialized cell types, making them a valuable system for studying how cellular diversity first arose.
Read more: Million-year-old mammoth tooth carries the oldest bacterial DNA ever found associated with a host
Ancient sea anemone cell identity revealed
To find out how cell identity is formed and maintained, the researchers analyzed approximately 60,000 individual sea anemone cells. Nematostella vectensis. The data set included cells from two life stages—adult animals and embryos in the early gastrula stage, when the basic body plan is still forming—allowing the team to capture both the developmental origins and states of mature cells.
Instead of grouping cells in which genes were active, the researchers focused on DNA regions that control gene activity. These regulatory elements act as control switches, determining when and where genes can be used. From this analysis, the team assembled a large catalog of more than 112,000 regulatory elements in the anemone genome—a surprisingly rich regulatory landscape for an animal of its size.
When cells were organized using these regulatory patterns, a different picture emerged. Instead of being grouped only by function, cells were grouped according to their developmental origins, showing which embryonic layers they came from. This made it possible to distinguish between cell types that perform similar roles but follow different developmental paths.
This difference was especially clear in muscle cells. Some muscle cells had similar functions and relied on the same genes, although they originated from different embryonic layers. Although their gene activity appeared similar, the regulatory instructions controlling the genes were completely different, showing that similar cell types can be built using different regulatory strategies.
Understanding the evolution of animal cell types
Cnidarians were among the first animals to develop specialized cell types, such as neurons and muscle cells. They also evolved a special cell called a cnidocyte, equipped with microscopic harpoon-like structures used for hunting and defense—the source of the familiar stings of jellyfish and sea anemones.
The results suggest that these early animals already had a flexible way to create new cell types. By tracing how cell identity was constructed in ancient animals, the study offers a new framework for understanding where animal cell types came from—and how today's biological complexity arose.
“This study opens up a whole new world of possibilities. In the future, we will explore the evolution of animal cells by comparing genomic sequence information, and for the first time we will be able to do this systematically and at scale,” said co-author Arnau Sebe-Pedros.
Read more: Bowhead whales can live up to 200 years, and their DNA may hold the secret to longevity
Article sources
Our authors in discovermagazine.com use peer-reviewed research and high-quality sources for our articles, and our editors review scientific accuracy and editorial standards. Review the sources used below for this article:
