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Seasonal body clocks

"Calendar cells" help animals adapt to the changing seasons.

Image of a group of sheep taken from a distance.

BBSRC funded researchers at The Roslin Institute and the University of Manchester have discovered the cells driving the annual body clock in animals which adapts their body to the changing seasons.

Cells in a structure called the ‘pars tuberalis’– which is situated in the pituitary gland – are specialized cells that respond according to how much daylight there is, providing an internal genetic calendar for the animal.  The activity of these “calendar cells” change dramatically over the year, with different proteins produced in winter or summer months.

The switching between proteins in calendar cells is what drives the seasonal cycle in sheep and other mammals. The seasonal clock found in sheep is likely to be the same in all vertebrates, or at least contains the same parts.

The next step is to understand how our cells record the passage of time.

For further reading please see our news story.

Original Publication

Wood SH et al. (2015) Binary switching of calendar cells in the pituitary defines the phase of the circannual cycle in mammals. Curr Biol. 25:2651-62. DOI: