Hello Nature readers, would you like to get this Briefing in your inbox free every day? Sign up here

Computer illustration of bacteriophages attacking E. coli cell

Bacteriophage viruses — seen attacking an E. coli cell in this computer illustration — can have exotic chemistries in their DNA.Credit: Maurizio De Angelis/Science Photo Library

Why phages have wildly different DNA

Some viruses that infect bacteria have ‘Z-DNA’, which uses a genetic alphabet different from the As, Ts, Cs and Gs in the DNA of nearly all other organisms. Dozens of these bacteriophages (or ‘phages’) write their genomes using a chemical base called 2-aminoadenine, Z for short, instead of adenine. Now, two teams have spelled out how the system works. These phages use specialized enzymes to make genes with an alternative nucleobase. “It represents the first discovery of a ‘shadow biosphere’ since [Carl] Woese identified the Archaea a half century ago,” says synthetic biologist Steven Benner.

Nature | 6 min read

Hardy genome: graphic that shows how the Z:T base pair forms three hydrogen bonds, compared to two in the A:T base pair.

Psychedelic drugs without the trip

An easier way to identify non-hallucinogenic psychedelics could aid treatment for illnesses such as depression and post-traumatic stress disorder. Researchers have designed a fluorescent sensor to predict whether a molecule is hallucinogenic, based on the structure of a brain receptor targeted by psychedelics.

COVID-19 coronavirus update

The first billion COVID vaccinations

The world has reached the milestone of administering one billion doses of COVID-19 vaccines, just four months after the World Health Organization (WHO) authorized the first vaccine for emergency use and roll-outs began in countries such as the United States and the United Kingdom. The speed at which they have been administered is remarkable, but unequal distribution of the vaccinations highlights global disparities. “It is an unprecedented scientific achievement. Nobody could have imagined that, within 16 months of the identification of a new virus, we would have vaccinated one billion people worldwide,” says WHO chief scientist Soumya Swaminathan.

Nature | 3 min read

Cuba’s homegrown vaccines

If everything goes to plan, Cuba could be the first Latin American country to develop and manufacture its own vaccine against COVID-19. The candidate, called Soberana 02, entered phase III trials in people in March. The name means ‘sovereign’ — a powerful concept in a country that has been hit hard by geopolitical discord. “We wanted to solely rely on our own capacities to vaccinate our population, not on other people’s decisions,” says vaccine designer Vicente Vérez Bencomo. “And life is proving us right. What we’re seeing across the world is that vaccine supplies are being hoarded by rich countries.”

Nature | 3 min read

Features & opinion

Futures: Hoist by her own Picard

Reruns of old science-fiction series help pass the time for the lone conscious passenger on a ship full of sleeping crew in the latest short story for Nature’s Futures series. But a catch-phrase turns out to be a passphrase — with humorously disastrous consequences.

Nature | 4 min read

Podcast: How individual neurons use energy

Researchers looked at individual fruit-fly neurons to better understand how energy use and information processing are linked — which might have important implications for brain imaging in humans.

The Nature Podcast’s special three-part series, Stick to the Science: when science gets political, has been shortlisted for a Webby award. It’s well worth a listen — and, if you liked it, please consider casting your vote in our favour.

Nature Podcast | 17 min listenSubscribe to the Nature Podcast on Apple Podcasts, Google Podcasts or Spotify.Reference: Nature paper

Health disparities

Inequality’s deadly toll

In California, low wages, weak labour protections and precarious immigration status are among the reasons that food and agricultural workers had an almost 40% increased risk of dying last year, compared with the risk for the state’s general population. A growing number of public-health researchers are saying it's time to move on from simply identifying the social determinants of health, and start pushing for leaders to address them. “The pandemic has turned up the dial, and to me it brings out a sense of urgency,” says medical geographer Arrianna Marie Planey. “I see a study saying COVID is higher in farmworkers, and I’m not interested — I want to know what’s next.”

Nature | 23 min read

BEHIND THE STORY: FROM THE REPORTER

Nature reporter Amy Msxmen interviews an agricultural worker in California.

Over the past eight months, I’ve witnessed how exploitation, poverty and discrimination drove COVID-19 in California’s San Joaquin Valley. Farmworkers told me that they felt their work was called essential, but their lives were treated as expendable. Scholars have connected these problems to disease over the past 150 years, so I’ve also been asking why so little has changed. Some of the researchers I talked with were frustrated with how scholarship mounts, but the problems aren’t addressed. This piece is about why change is so hard, and what can be done.

Amy Maxmen, Nature senior reporter

Nature | 23 min read

NOTABLE QUOTABLE

“As scientists, we have a societal responsibility to talk about this — we’re the ones in the trenches taking care of people, and analysing the data on disparities first-hand.”

Anthony Fauci, the highest-ranking infectious-disease scientist in the US government, says that it’s time to discuss health disparities that are rooted in systemic racism and economic inequality.

Quote of the day

“It was not possible to put a croissant in a can and have it thermo-stabilized.”

Croissants did not accompany French astronaut Thomas Pesquet to the International Space Station, says space scientist Alain Maillet — but lobster, beef bourguignon and almond tarts did. (The New York Times | 10 min read)