Hello Nature readers,
Today we marvel at a coloured map of neurons in a mouse brain, learn the structure of the taste receptor responsible for sweetness and explore a class of drugs offering hope for rare children's cancers.

Mouse brains: now in technicolour

A trick that inflates tissue samples to 16 times their original size has allowed scientists to map intricate patterns of cells in mouse brains with a cheap-and-cheerful light microscope. The approach, which uses gels that expand in water, makes details visible down to individual synapses — the junctions between neurons. Researchers behind the technique have used artificial intelligence to create colourful maps that show how brain cells connect, which molecules they use to communicate and whether their signals excite or silence other cells.

Hospital superbug eats medical plastic

Pseudomonas aeruginosa — a strain of bacterium that often causes antibiotic-resistant infections in hospitals — can produce an enzyme that can break down medical-grade plastic. Researchers found that the enzyme, dubbed Pap1, can break down a plastic called polycaprolactone that is commonly used in health care because of its biodegradable properties. The ability to break down plastic could explain why these microbes persist in hospital environments, says biomedical scientist and study co-author Ronan McCarthy.

How we taste sweetness

After more than 20 years of trying, scientists have mapped the molecular structure of the taste receptor responsible for our perception of sweetness. They’ve also shown how two of the most widely consumed artificial sweeteners bind to the receptor and activate it. “This single receptor is responsible for our insatiable, never-ending attraction to sugar,” says neuroscientist and study co-author Charles Zuker. “And now that we have this structure, perhaps we can find ways to modulate its function.”

Children bear the brunt of climate change

More than half of the children born in 2020 will face unprecedented exposure to heatwaves over their lifetime — even under a conservative projection for how climate change will unfold over the next 75 years. Under a more pessimistic forecast, that figure rises to 92%, compared with just 16% of those born in 1960. The study is among the first to pinpoint the generations and numbers of people that will experience an “unprecedented life” in terms of extreme heat, says climate scientist Wim Thiery.

A ‘kiss of death’ for cancer-related proteins

Childhood solid tumours are unbearably cruel: they account for more than half of cancer-associated deaths in kids under 14 in the United States and few new cancer drugs have been approved for them. Now hope is on the horizon thanks to PROTACs — short for proteolysis-targeting chimeras — laboratory-made molecules that hijack the cell’s protein-disposal machinery. Typical drugs gum up the business end of a protein to inhibit its activity, while PROTACs eliminate the protein altogether. And the technology could target many other cancers too, as well as other diseases. Hard-to-drug proteins inside cells have roles in nearly every disease.

‘I hear their voices and their stories’

Behavioural-health researcher Jason ‘Jace’ Flatt has lost nearly US$5 million in federal grants because their research into health disparities experienced by LGBTQIA+ people is not valued by the Trump administration. But they are determined to continue. “These are my people, and I want to make sure they’re taken care of,” says Flatt. “They’re the reason I can be married to my husband, and they’re the reason that I can be out at my job and not worry.”

Why you should write your intro last

Few things are as daunting as figuring out how — and where — to begin writing your PhD thesis. But considering the central statement of your entire research project can make structuring your writing much easier, suggests geographer Tuuli Toivonen. Her recipe for a clear synopsis includes:

• Identifying your claims
• Structuring your introductory chapter around the claims
• Writing the introduction, background and data and methods sections last