When something is not right, signals of some sort are sent out. While many are obvious - an engine gone dead, water flooding a basement, flames protruding from a rooftop - others are more subtle: the slim crack in a dam before its collapse, the ray of sun about to set off a forest fire, the faint smell of gas before an explosion. Humans have developed ways of sensing and measuring these more discreet signals in the hope of predicting and preventing catastrophes. On a far smaller scale, cells too have ways of sensing something that has gone wrong. This can be in the form of entities such as molecules - either foreign or synthesized by the cell itself in situations of stress - which trigger off defence mechanisms. It can also be something far less tangible, such as patterns. Patterns? Imagine small weaving inaccuracies in cloth for example. This is not unlike unusual conformations which may arise in stretches of DNA or RNA (known as Z-DNA or Z-RNA) when cells are dealing with stress such as viral infection for instance. While, in the 17th Century, Antonie van Leeuwenhoek perfected the magnifying lens to spot stray stitches in cloth, over time cells have perfected their own lens to spy Z-DNA and Z-RNA: a protein known as ZBP1. Read more