Scientists say they've witnessed a never-before-seen type of reproduction in organic robots created in the lab using frog cells.
The discovery involves a xenobot—a simple, "programmable" organism that is created by bringing stem cells together in a lab. "You can think about this like using the different cells as building blocks like you would build with LEGO," Douglas Blackiston, a co-author of the study says. The xenobots are made of cells taken from an African frog. The cells aren't genetically changed at all, but simply combined in different arrangements to produce the xenobots, says Blackiston. What the xenobots did—self-replication—is new in living organisms, says Michael Levin, a professor of biology at Tufts. It does happen at the molecular (分子的) level, but "we are not aware of any organism that reproduces in this way," he says.
Xenobots are collections of living cells and have no brain or digestive system. But in a real sense they can be programmed—to corral other cells, as in this study, or eventually to do other things. That's why the researchers think of them as tiny organic robots. "The distinction between a robot and an organism is not nearly as sharp as... we used to think it was," Levin says. "These creatures, they have properties of both."
The xenobots fuel themselves by using tiny hair-like structures. They have a tendency to spin, which "turns out to be pretty good for collecting piles of things," such as other cells, Blackiston says. So the team used an artificial intelligence-driven computer simulation (模拟图像) to see how they might control the xenobots into shapes that would be even better at piling things up. The researchers hope that one day these xenobots could be programmed to perform useful functions such as finding cancer cells in the human body or trapping harmful microplastics in the ocean.
But that concerns some scientists. Nita Farahany is a professor who studies the ethics involved in new technologies and was not part of the xenobot research. "Any time we try to improve life by means of tech... we should recognize its potential to go really poor," she said.
