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Microscopic image of a zebrafish embryo 22 hours postfertilization

Developing embryos, such as this zebrafish, rely on physical forces to sculpt them as they grow.Credit: Philipp Keller/HHMI Janelia Research Campus

Bend, squeeze and pull: the mechanics of life

An embryo develops from a sphere of cells thanks, in part, to the forces that squeeze, bend and tug the growing animal into shape. Even when it reaches adulthood, its cells will continue to respond to pushing and pulling — by each other and from the environment. Yet how bodies and tissues take form remains “one of the most important, and still poorly understood, questions of our time”, says developmental biologist Amy Shyer. Researchers have begun to define the mechanisms by which cells sense, respond to and generate forces using innovative tools and techniques, both in vitro and in whole animals.

Nature | 10 min read

How cells might sense Earth’s magnetic field

Glowing cells offer clues to the mysterious mechanism that animals such as birds, bats, eels and whales might use to navigate using Earth’s magnetic field. Cryptochrome, a protein found in plants and animals that can absorb light and emit an electromagnetic signal, has been a prime suspect for the source of magnetoreception — the ability to detect magnetic fields. Using a specialized microscope, scientists irradiated human cells, which caused cryptochromes to fluoresce. But when the researchers passed magnets over the cells, the fluorescence dropped. It’s the first time that cryptochromes have been observed responding to magnetic fields in a living cell.

Forbes | 5 min read

Reference: PNAS paper

History points to ‘imminent extinction’ of Tapanuli orangutan

The Tapanuli orangutan (Pongo tapanuliensis) is the most threatened great ape species in the world — and history indicates that its future is even bleaker than we thought. Researchers combed newspapers, journals, books and museum records from as far back as the early nineteenth century to piece together the species’s historical range. They found that, even before industrial agriculture and large infrastructure projects, hunting and small-scale farming drove the ape out of its natural habitat and into the remote mountains. Now, fewer than 800 individuals survive in locations where they were never adapted to live, say the authors. “Claims by the Indonesian Ministry of Environment and Forestry that the Tapanuli orangutan has ample habitat and [does] not face extinction need to be carefully reassessed, because they are not supported by historic information,” says conservation scientist Erik Meijaard.

Mongabay | 9 min read

Reference: PLoS One paper

Pulsars hint at sea of gravitational waves

Astronomers might have spied their first hint of gravitational waves made by merging supermassive black holes. For more than a decade, the NANOGrav collaboration has been monitoring radio waves from 45 spinning stars, known as pulsars. Tiny deviations in the arrival times of the waves could reveal the cumulative ripples in space-time caused by merging supermassive black holes across the Universe. An analysis of more than 12 years of data shows preliminary evidence for the effect. The hints suggest “that we are bobbing in a sea of gravitational waves rippling from supermassive black hole mergers in galaxies across the universe”, says astrophysicist Julie Comerford.

Physics World | 6 min read

Reference: The Astrophysical Journal Letters paper

COVID-19 coronavirus update

Will vaccines stop transmission?

Scientists don’t yet know whether vaccinated people can spread COVID-19. Although vaccines have been proven to protect recipients from getting ill, research has yet to determine whether they prevent the virus from replicating altogether. Vaccines are known to prompt the body to make the IgG antibodies inside our bodies. But whether they also trigger IgA antibodies, which exist in the outward-facing mucosal surfaces such as the nose and throat, is not known, and these could be more important in preventing transmission. For now, the takeaway message is that vaccinated people should stay vigilant about protecting others.

Quartz | 3 min read

Notable quotable

“Until COVAX gets the support it deserves, there is little hope of vaccinating the most vulnerable one-fifth of humanity.”

The race to buy up vaccine stocks is undermining a pioneering global effort to save lives and end the pandemic, argues a Nature editorial.

Features & opinion

How to take ‘the future of democracy’ online

Governments are increasingly turning to the public through processes such as citizens’ assemblies and juries. “Giving citizens a meaningful role in decision-making can help them to make hard choices and increase public trust,” writes participatory-democracy researcher Claudia Chwalisz. “Despite the constant run of distressing news, these trends give me hope for the future of democracy.” We shouldn’t take these successes for granted now that the events of 2020 have moved much of this online, she argues. She proposes a cautious approach focused on understanding the trade-offs involved with face-to-face and digital discussions.

Nature | 5 min read

Tiny gizmos need tiny batteries

Robots and sensors that are so small they’re known as ‘smart dust’ need tiny batteries to power them. To shrink batteries,, write nano-scientists Minshen Zhu and Oliver Schmidt, we need advances in two areas: energy-dense, durable materials to improve charge storage, and clever architectures to compress and combine components. Zhu and Schmidt call on electrical engineers and battery and polymer scientists to work more closely to overcome these problems.

Nature | 9 min read

Four ways to shrink batteries. Graphic showing current and new ways of making batteries smaller.

Source: M. Zhu & O. G. Schmidt

The origins of ‘video-chat voice’

Audio scientists explain the software compromises that can make our most-familiar friends and colleagues sound not quite right over video chats, and how to improve things so we sound more natural.

• Bring the microphone closer — computers are not as good as our brains are at focusing on important sounds.

• Think about reverberation. Sound-absorbing rugs and curtains — and even other people — can help to improve the sound of a call.

• To maximize the feeling of being in the same room, aim to call from similarly reverberant spaces.

The New Yorker | 6 min read

Correspondence: your letters to Nature

• Reshoring agriculture in the European Union risks undermining the United Nations’ sustainable development goals, write conservation scientists Erik Meijaard, Douglas Sheil and Daniel Murdiyarso. “The EU must avoid isolationism and support those willing to attain good production standards, wherever they are,” they argue.

• Online gaming has increased during the COVID-19 pandemic, notes psychologists Daniel King, Joël Billieux and Paul Delfabbro. They urge technology companies to collaborate with scientists to help ensure that these activities don’t strengthen bad habits and create social difficulties once the crisis has subsided — particularly for vulnerable or underage individuals.

• Breast-cancer screening and smoking cessation are among the success stories for community-led public-health communication, write public-health researchers Renee Wurth and Herman Saksono. They call on health organizations and technology firms to work with community advocates to ensure that vaccine hesitancy does not widen the racial and ethnic disparities already exposed by the COVID-19 pandemic.

Correspondence is published every week in Nature. For more info on writing one yourself, please see the guidance on nature.com. (Your feedback on this newsletter is always welcome at briefing@nature.com, but won’t be considered for publication in Nature.)