The original version of this story appeared in Quanta Magazine. Far from being a solo operator, most single-celled microbes are in complex relationships. In the sea, soil, and your gut, they can fight and eat each other, exchange DNA, compete for nutrients, or eat byproducts. Sometimes they become more intimate: One cell can enter another cell and make it comfortable. If the conditions are right, they may stay and be welcomed, creating relationships that can last for generations—or even billions of years. The phenomenon of one cell living inside another cell, called endosymbiosis, has led to the evolution of complex life. Examples of endosymbiosis are everywhere. Mitochondria, the energy factories in your cells, were once free-living bacteria. Photosynthetic plants owe their sun-spun sugars to chloroplasts, which also come from independent organisms. Many insects get their essential nutrients from the bacteria that live inside them. And last year, researchers discovered “nitroplasts,” an endosymbiont that helps some algae process nitrogen. So much of life depends on endosymbiotic relationships, but scientists have struggled to understand how this happens. How can internal cells avoid digestion? How to learn to reproduce on the host? What makes the random joining of two independent organisms into a stable and lasting partnership? Now, for the first time, researchers have observed the opening choreography of this microscopic dance by inducing endosymbiosis in the laboratory. After injecting the bacteria into the fungus — a process that required creative problem solving (and a bicycle pump) — the researchers were able to elicit cooperation without killing the bacteria or the host. These observations provide a picture of the conditions that make the same thing happen in the microbial free world. These cells can even be regulated faster than anticipated. “To me, this means organisms want to live together, and symbiosis is the norm,” said Vasilis Kokkoris, a mycologist who studies the biology of symbiotic cells at the VU University in Amsterdam and was not involved in the new study. “So it’s big, big news for me and the world.” Short initial attempts show that most mobile love affairs are unsuccessful. But by understanding how, why, and when organisms receive endosymbionts, researchers can better understand key moments in evolution, and also have the potential to develop synthetic cells engineered with superpowered endosymbionts. Cell Wall Breakthrough Julia Vorholt, a microbiologist at the Swiss Federal Institute of Technology Zurich in Switzerland, has long puzzled over the state of endosymbiosis. Researchers in the field consider that when bacteria enter the host cell, the relationship between infection and harmony. If the bacteria reproduce too quickly, it risks depleting the host’s resources and triggering an immune response, resulting in the death of the guest, the host, or both. If reproduction is too slow, it will not be in the cell. Only in rare cases, they think, can bacteria achieve Goldilocks levels of reproduction. Then, to become a true endosymbiont, it must infiltrate the host’s reproductive cycle to ride the next generation. Finally, the host’s genome must eventually mutate to accommodate the bacteria – allowing the two to evolve as a unit. “He became addicted,” Vorholt said.
Scientists Create Conditions That Cause Complex Life
