Physiology

Characterizing a 12-hour biological clock

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Science  30 Jun 2017:
Vol. 356, Issue 6345, pp. 1347-1348
DOI: 10.1126/science.356.6345.1347-b

A mathematical analysis of changes in gene expression in mouse liver, designed to detect oscillations of various frequencies, showed more than 3500 genes whose expression cycled with a 12-hour period. This is distinct from circadian gene expression, which is coupled to the 24-hour light cycle, and has been noted before in marine animals, perhaps because of a need to synch with 12-hour tidal changes. Zhu et al. found that gene products associated with 12-hour cycles are particularly related to metabolic function, endoplasmic reticulum stress, and the unfolded protein response. The 12-hour clock appears to be distinct from the well-known circadian oscillator and was evident in nematodes and crustaceans, as well as mammals.

Cell Metab. 10.1016/j.cmet.2017.05.004 (2017).

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