BIRS Workshop Lecture Videos

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BIRS Workshop Lecture Videos

Marching to the cell-cycle drum beat: Entrainment of a synthetic oscillator in budding yeast Buchler, Nicolas


We have built a synthetic two-gene oscillator in budding yeast using a transcriptional activator and inhibitor pair. The gene circuit topology is similar to the core motif commonly found in circadian clocks. We measured gene dynamics in single cells with fluorescent protein reporters and timelapse microscopy. Our synthetic oscillators have the same period as the cell cycle across a wide range of growth conditions. To distinguish whether our synthetic oscillator was driven by the cell cycle or entrained by it, we blocked the yeast cell cycle using mating pheromone or nocodazole. In both cases, gene oscillation persisted with an intrinsic period similar to the cell cycle. This suggests that our two-gene oscillator can function autonomously. However, in the presence of the cell cycle, its similar period and unknown coupling leads to strong entrainment. As a point of contact with the BIRS workshop, we welcome methods of analysis compatible with our data (e.g. gene oscillation and coupling in single cells) that can evaluate the “quality” of the oscillation, elucidate entrainment conditions, and perhaps reveal modes or mechanisms of coupling.\\r\\n\\r\\nWe have also measured the expression of constitutive genes to understand how and where a synthetic oscillator might couple to the cell cycle. Using power spectral analysis, we showed that the cell-cycle drumbeat persists, even in constitutively expressed genes. Several possible explanations include cell-cycle oscillations in growth rate and DNA synthesis. Strikingly, we have also shown that the cell-cycle drumbeat occurs in fission yeast and bacteria. This suggests that cell-cycle entrainment could be a widespread and generic phenomenon.

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