Researchers at the Marine Biological Laboratory found that C. matruchotii, one of the most prevalent bacteria in the mouth, can split into up to 14 new cells at once, rather than the typical two new cells. (wissanu_phiphithaphong/iStock)
Immune memory and a toothsome discovery.
Something to chew on
Dental plaque—the thin film on your teeth where they meet your gums—is composed of hundreds of types of bacteria. One of the most prevalent, Corynebacterium matruchotii (it’s a mouthful), functions as scaffolding for other bacteria in the oral microbiome. Until recently, the process by which C. matruchotii grow and reproduce eluded scientists. To make the bacterium easier to study, researchers at the Marine Biological Laboratory dyed the organism with fluorescent amino acids and recorded a time-lapse video of its growth. They discovered that C. matruchotii is able to split into up to 14 new cells at once, in a kind of reproduction known as multiple fission. This division strategy is rare in the broader bacterial kingdom, where the vast majority of bacteria split into only two new cells. Because of how intertwined C. matruchotii is with other bacteria, these discoveries help account for the spatial organization of the entire oral microbiome. The study was published September 3 in the Proceedings of the National Academy of Sciences.
Innate memory
What we think of as the immune system is really two systems. The innate immune system offers nonspecific protection against any invader that enters the body, while the adaptive immune system learns how to recognize and combat specific pathogens. In 2012, however, researchers discovered that the innate immune system can also “remember” like the adaptive immune system does; innate immune memory, or trained immunity, has been observed in response to, for instance, the tuberculosis vaccine. A team led by Aaron Esser-Kahn of the Pritzker School of Molecular Engineering wanted to see if any small-molecule drugs—pharmaceuticals that are typically administered orally and can easily pass through cell membranes—might have similar effects. After testing some 2,000 drugs, the researchers made the surprising discovery that steroids induced trained immunity in mice—an unexpected result, given that steroids are often used to suppress immune responses like inflammation. The finding could lead to new cancer treatments and improved vaccines. The research was published in the Proceedings of the National Academy of Sciences in July.