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The Lives of Prions

A new study published in Nature is elucidating the role that prions may play in the evolution of yeast, reports New Scientist's Andy Coghlan. Researchers at the Whitehead Institute for Biomedical Research show that yeast undergoes a kind of "combinatorial evolution" where it is able to transform a protein called Sup35 into a prion in times of stress, which then leads to the production of new proteins that were previously not needed, some of which may be helpful to the yeast's survival — all without any changes to the yeast's DNA. "[Whitehead researcher Susan] Lindquist grew the yeast in a hostile environment — either oxygen-depleted or abnormally acidic, for example — and then exposed the survivors to a chemical that destroys prions," Coghlan says. "Many colonies withered, showing that the prions were responsible for their competitive edge. What's more, the prions are passed down in mating, so daughter cells will also make the same suite of survivor proteins."

Although it's currently unclear whether this prion method of evolution applies to species other than yeast, the implication, the researchers say, is that not all evolution is driven through changes to DNA.

The Scan

Tens of Millions Saved

The Associated Press writes that vaccines against COVID-19 saved an estimated 20 million lives in their first year.

Supersized Bacterium

NPR reports that researchers have found and characterized a bacterium that is visible to the naked eye.

Also Subvariants

Moderna says its bivalent SARS-CoV-2 vaccine leads to a strong immune response against Omicron subvariants, the Wall Street Journal reports.

Science Papers Present Gene-Edited Mouse Models of Liver Cancer, Hürthle Cell Carcinoma Analysis

In Science this week: a collection of mouse models of primary liver cancer, and more.