Genome-wide analyses of circadian systems.

Circadian gene expression is a pervasive feature of tissue physiology, regulating approx. 10% of transcript and protein abundance in tissues such as the liver. Technological developments have accelerated our ability to probe circadian variation of gene expression, in particular by using microarrays. Recent advances in high-throughput sequencing have similarly led to novel insights into the regulation of genes at the DNA and chromatin levels. Furthermore, tools such as RNA interference are being used to perturb gene function at a truly systems level, allowing dissection of the clockwork in increasing depth. This chapter will highlight progress in these areas, focusing on key techniques that have helped, and will continue to help, with the investigation of circadian physiology.