‘Cell blocks’ astound researchers
Specially shaped blocks made of certain stem cells are reminiscent of the game “Pac-Man”. But instead of eating other stem cells, they are building new cell formations independently and very effectively. Is this ability related to the origin of life?
aAmerican scientists have discovered a new method of self-reproduction. They report that clumps of stem cells from the clawed frog (Xenopus laevis) are able to “build” more of these formations. Spherical cell masses have small hairs on the outside and can therefore move through laboratory vessels.
If there are also many individual stem cells in the vessel, it pushes them together in piles that develop into mobile clumps of cells within a few days. A group led by Josh Bongaard of the University of Vermont at Burlington He describes these processes in the journal “Proceedings of the National Academy of Sciences.” (PNAS). “This form of continuity, not yet seen in any organism, occurs spontaneously over days rather than thousands of years,” the researchers wrote.
They first examined stem cells that they had taken from clawed frog embryos at a particular stage, the blastula. They have left some cells bound together or re-contact the cells after isolation. In both cases, this resulted in a clumping of the autologous cells with the hair. In a nutrient medium in a petri dish and several individual stem cells of clawed frogs, the cell clumps perform circular motions that push the cells into mounds, so that more hairy clumps appear.
In computer simulations, Bongard and colleagues looked for the shapes of these cell masses that could push cells together more efficiently. With the help of artificial intelligence, they have improved these shapes. The donut-shaped structure with a wedge-shaped gap proved to be very effective. viewed from the side Does he look like Pac-Man? From the computer game of the same name. However, the Hulk did not eat the stem cells, but rather pushed them together.
In the lab, scientists cut small pieces of cell clumps, creating vacuoles—in fact, clumps of cells of different shapes pushed larger groups of cells together on average. These clusters are more likely to develop into clumps – it takes at least 50 cells to do so. While spherical cell clumps produced a maximum of two generations, Pac-Man cell clumps produced up to four generations.
“Although kinetic self-reproduction has not been observed in current cellular life forms, it may be necessary for the origin of life,” the scientists wrote. Amyloids (protein complexes) show similar abilities to make copies of themselves. This can precede any form of genetic code. Some amyloids are also linked to the development of mental illness In the context of. In further computer modeling, the researchers attempted to discover how this natural phenomenon could be used in practice.
They simulated lab vessels with cell blocks, individual stem cells, micropower supplies, light sources and interrupted wires. And the more clump-cell activity in the lab bowl, the more lights were lit. In the model, Bongaard’s team asked groups of cells to compete with the robot arm: While the number of lights occupied by the robot is a straight line slightly high in the diagram, the light curve of the self-replicating cell groups rises more steeply. Shows one exponential growth. This enabled groups of cells to solve the task in the model more efficiently than robots.
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