Forward genetic approaches to circadian clocks in mice.

The study of mammalian circadian rhythms has a rich history of physiological understanding, but the molecular elements of the mammalian clock remain to be discovered. Availability of effective mutagenesis procedures and mouse molecular genetics resources sufficient for the task of positional cloning give cause for hope that the Clock gene, as well as other components of the mammalian circadian system, will be identified soon. The isolation of Clock in a deliberate mutagenesis screen provides an important proof-of-principle that forward genetics can be successfully applied toward the discovery of novel genes underlying complex behaviors in mice.