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Scientists have successfully engineered human blood cells to transform into immature sperm and incubated them in a small sac grown in a mouse kidney. The blood cells were reprogrammed into induced pluripotent stem cells, which the team was able to “convince” to become embryonic cells that can give rise to eggs or sperm. The researchers then mixed the immature cells with non-reproductive cells found in the testes of developing mice, which provide the environment for sperm development. The procedure is a step towards producing mature sperm in the laboratory.

Nature | 5 minutes of reading

Reference: cell stem cell paper

The central conclusions of biomedical preprints rarely change during the peer review process, according to a study of more than 70,000 preprints. The study, which is currently a preprint, found that nearly 40% of the main conclusions remained unchanged between the preprint and journal-published versions of the article abstracts, and another 50% underwent only minor revisions. The authors say the findings suggest that preprints are a reliable source of information, although some scientists say the finding should be interpreted more cautiously. The study only included preprints that were published in a journal, so it did not evaluate the veracity of unpublished preprints.

Nature | 5 minutes of reading

Reference: bioRxiv preprint (not peer-reviewed)

The US National Science Foundation (NSF) is planning to expropriate money from its core science programs to fund an initiative by the White House Office of Science and Technology Policy (OSTP), say NSF staff members and an internal NSF ledger seen by Nature. The measure would force the agency to terminate funding for research proposals that are nearly finalized. The OSTP did not respond to Naturerequest for comment, nor the offices of lawmakers who oversee NSF spending plans. An NSF spokesperson denied reports that funds would be redirected to a handful of so-called ‘X-Labs’ that focus on applied research. NSF staff members who spoke with Nature They say they fear retaliation if they speak out and are not allowed to pass on what they know to investigators. “We don’t know where the money is going or what’s happening,” one said. “We can’t communicate with the community at all. We are banned.”

Nature | 6 minutes of reading

Hannibal’s historic crossing of the Alps probably passed over the Col de la Traversette, because otherwise his army would have starved. The almost 3,000 meter high pass is the most energy efficient route through the Alps. Still, researchers estimated that the 15-day journey would have required more than 230 tons of food and supplies for the Carthaginian army of 46,000 men, 7,000 horses and 37 war elephants.

Nautilus | 4 minutes of reading

Reference: Proceedings of the National Academy of Sciences paper

Features and opinion

In Incrediblescientific journalist and Nature Editor Helen Pearson charts the rise of evidence-based medicine and explores how rigorous research has transformed health and social policy. Pearson shares examples of success stories, where strong evidence overturned bad practices and the people behind them, many of whom were treated as mavericks for defending randomized trials. “Anyone can read and enjoy the book, but there are details for experienced readers,” public policy researcher Peter John writes in his review. “The author writes as a believer and her passion is captivating.”

Nature | 8 minutes of reading

in this week Informative talkI joined host Benjamin Thompson to discuss the legacy of Dolly the Sheep; the first mammal cloned from an adult cell. And we were excited by the first real-time observations of a mid-ocean ridge breaking apart.

Nature Podcast | 10 minutes listen

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On Friday, Leif Penguinson was surveying a swamp in the forest tundra of the Arkhangelsk region, Russia. Did you find the penguin? When you’re ready, here’s the answer.

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