There are plenty of unanswered questions about the origin of life on Earth. But the research community has largely reached consensus that one of the key steps was the emergence of an RNA molecule that could replicate itself. RNA, like its more famous relative DNA, can carry genetic information. But it can also fold up into three-dimensional structures that act as catalysts. These two features have led to the suggestion that early life was protein-free, with RNA handling both heredity and catalyzing a simple metabolism.

For this to work, one of the reactions that the early RNAs would need to catalyze is the copying of RNA molecules, without which any sort of heritability would be impossible. While we've found a number of catalytic RNAs that can copy other molecules, none have been able to perform a key reaction: making a copy of themselves. Now, however, a team has found an incredibly short piece of RNA—just 45 bases long—that can make a copy of itself.

Finding an RNA polymerase

We have identified a large number of catalytic RNAs (generically called ribozymes, for RNA-based enzymes), and some of them can catalyze reactions involving other RNAs. A handful of these are ligases, which link together two RNA molecules. In some cases, they need these molecules to be held together by a third RNA molecule that base pairs with both of them. We've only identified a few that can act as polymerases, which add RNA bases to a growing molecule, one at a time, with each new addition base pairing with a template molecule.

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Vinay Prasad, the Trump administration's top vaccine regulator at the Food and Drug Administration, single-handedly decided to refuse to review Moderna's mRNA flu vaccine, overruling agency scientists, according to reports from Stat News and The Wall Street Journal.

Stat was first to report, based on unnamed FDA sources, that a team of career scientists at the agency was ready to review the vaccine and that David Kaslow, a top career official who reviews vaccines, even wrote a memo objecting to Prasad’s rejection. The memo reportedly included a detailed explanation of why the review should proceed.

The Wall Street Journal confirmed the report with its own sources, who added that FDA scientists attended an hourlong meeting with Prasad in early January, in which they laid out their objections to Prasad's plans to block the vaccine review. They reportedly told Prasad—a political appointee known for causing turmoil and espousing anti-vaccine rhetoric—that it was the wrong approach.

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The Food and Drug Administration has refused to review Moderna's application for an mRNA flu vaccine, the company revealed Tuesday.

While the move came as a surprise to the high-profile vaccine maker, it is just the latest hostility toward vaccines—and mRNA vaccines in particular—from an agency overseen by the fervent anti-vaccine activist Robert F. Kennedy Jr. In his first year in office, Kennedy has already dramatically slashed childhood vaccine recommendations and canceled $500 million in research funding for mRNA vaccines against potential pandemic threats.

In a news release late Tuesday, Moderna said it was blindsided by the FDA's refusal, which the FDA cited as being due to the design of the company's Phase 3 trial for its mRNA flu vaccine, dubbed mRNA-1010. Specifically, the FDA's rejection was over the comparator vaccine Moderna used.

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