A fable of too much too fast

摘要

This is a tale of two organisms from two kingdoms that hail from very different habitats and that have nothing in common other than their ability to keep time, albeit using wholly distinct circadian systems. In this issue, Xu et al. (page 116) and Zhou et al. (page 111) respectively studied a freshwater cyanobacterium and a fungus. What these studies share is the fact that each organism has exploited the phenomenon of codon-usage bias to produce less of certain proteins and thereby build a more useful circadian clock. This modern fable features model organisms used in clever ways to reveal something new and confirm something old, and it reminds us that the goal of evolution is not necessarily to do more of something, but to do it better.