original version of this story Published in Quanta Magazine.
Most unicellular microorganisms do not act alone, but rather in complex relationships. In the ocean, soil, and gut, they may fight and eat each other, exchange DNA, compete for nutrients, and eat each other’s byproducts. In some cases, they can become even more intimate. One cell may slip into another for comfort. If the conditions are right, it can spark relationships that are sustained, welcomed, and last for generations or even billions of years. This phenomenon, where one cell lives inside another, is called endosymbiosis and has facilitated the evolution of complex life.
Examples of endosymbiosis are everywhere. Mitochondria, the energy factories within cells, were once free-living bacteria. Photosynthetic plants rely on chloroplasts to produce sugars spun by sunlight, but chloroplasts were originally independent organisms. Many insects obtain essential nutrients from the bacteria that live inside their bodies. And last year, researchers discovered nitroplasts, endosymbionts that help some algae process nitrogen.
Much of life depends on endosymbiotic relationships, but scientists have struggled to understand how they occur. How do internalized cells avoid digestion? How do they learn to reproduce within a host? Two independent organisms randomly fuse to form a stable, permanent Why are such partnerships formed?
Now, for the first time, researchers have observed the opening choreography of this microscopic dance by inducing endosymbiosis in the laboratory. After injecting bacteria into the fungus, a process that required some creative problem solving (and a bicycle pump), the researchers were able to evoke cooperation without killing the bacteria or the host. Their observations offer a glimpse into the conditions that allow the same thing to happen in microorganisms in the wild.
The cells adapted to each other faster than expected. “For me, this means that organisms actually want to live together and that symbiosis is the norm,” says the mycologist, who studies the cell biology of symbiosis at VU University in Amsterdam. Vasilis Kokkoris said. He was not involved in this new study. “That’s big news for me and for the world.”
Early attempts failed, but it became clear that most intracellular love affairs were doomed to failure. But understanding how, why, and when organisms embrace endosymbionts can help researchers better understand key moments in evolution, and how powerful endosymbionts can be used to manipulate It is also possible to develop synthetic cells.
Breakthrough of cell wall
Julia Volholt, a microbiologist at the Swiss Federal Institute of Technology Zurich, has long been puzzled by the state of endosymbiosis. Researchers in the field theorized that when bacteria invade host cells, the relationship between infection and harmony becomes shaky. If bacteria reproduce too quickly, they run the risk of depleting the host’s resources, triggering an immune response, and resulting in the death of the guest, host, or both. If they grow too slowly, they will not colonize the cells. They reasoned that the bacteria would only reach Goldilocks reproductive rates in rare cases. Then, to become a true endosymbiont, it must invade the host’s reproductive cycle and take over the next generation. Finally, the host genome must eventually mutate to adapt to the bacterium, allowing the two to evolve as one unit.
“They become addicted to each other,” Voholt says.
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