Our cells use a sugary language to identify and interact with each other. Cracking it will let us marshal stem cells and create alternatives to antibiotics

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NOT a lot of people know this, but babies are made with a handshake. True, that isn’t all that is involved. Often it starts with two people falling in love. But at some point biology takes over and a sperm must burrow its way into an egg. There is, however, more to the story.

On reaching the egg, the sperm meets the zona pellucida, a thick jacket of sugars that only sperm cells have the right biochemical tools to grab hold of. That “molecular handshake”, as Kamil Godula at the University of California, San Diego, puts it, is the most crucial step in the process that gets human life started.

Sugary handshakes aren’t just involved in baby-making. It turns out that every type of cell in our bodies has a unique sugar coating. And whenever anything interacts with a cell, it must recognise that sugar code and use the appropriate secret handshake. It happens when bacteria and viruses infect us, when a growing brain cell feels its way past its neighbours, and when our stem cells receive the marching orders that will define what type of tissue they will develop into.

Learn to read and write this sugary language, then, and we would have a powerful new way of intervening in cells’ activities to control disease and plenty besides. It won’t be easy. Unlike DNA, this code is fiendishly complex. But we are finally beginning to master the language of our cells.

To see why the sugar code is so important, try imagining you are a bacterium, says Bruce Turnbull, a chemist at the University of Leeds, …