Based on these results, we conclude that discrete, species-specific head shapes can be achieved by manipulating the connectivity of physiological networks in the planarian flatworm during head regeneration. Incredibly, this caused the flatworms to grow not just new tissue, but entirely new heads – heads belonging to completely different species of flatworm: S. mediterranea, D. japonica, and P. felina. Computational Modeling of Head Shape Formation The different head morphologies we observed, which are distinct in outward anatomy, distribution of the stem cells, and shape of the brain, must result from differential cell migration and cell-cell communication.
– Worms can grow the head and brain of another species? Then maybe we can do better at regenerating our own organs and tissues. That's the thrust of a new study by researchers who got flatworms to grow the heads of other flatworm species without any alteration to the worms' DNA, LiveScience reports. The researchers just altered the way proteins communicated between the flatworms' cells. "It is commonly thought that the sequence and structure of chromatin—the material that makes up chromosomes—determine the shape of an organism," says study researcher Michael Levin in a press release. "But these results show that the function of physiological networks can override the species-specific default anatomy." The researchers began by decapitating freshwater flatworms called Girardia dorotocephala, which are are able to regrow severed tissues; they have stem cells that can turn into any other kind of cell (we have similar cells, but only as early embyros). Researchers then used a kind of alcohol to alter electrical impulses that cells send through protein channels in the worms, IFL Science reports. Amazingly, some of the worms grew heads that were rounded, triangular, or had pointy ears—and all from other species. The worms eventually grew back their own heads, with their DNA fully intact. "This kind of information will be crucial for advances in regenerative medicine, as well as a better understanding of evolutionary biology," says Maya Emmons-Bell, first author of the study.