Many biochemical oscillators are driven by the periodic rise and fall of protein concentrations or activities. A negative feedback loop underlies such oscillations. The feedback can act on different parts of the biochemical network. Jan and Sarah mathematically compare time-delay models where the feedback affects production and degradation and how both mechanisms impose different constraints on the production and degradation rates that allow for oscillations. Nice work, Jan and Sarah, for more details check out their paper published in Journal of the Royal Society Interface.