Telling the Seasons Underground: The Circadian Clock and Ambient Temperature Shape Light Exposure and Photoperiodism in a Subterranean Rodent

FLÔRES, DANILO E. F. L.; JANNETTI, MILENE G.; IMPROTA, GIOVANE C.; TACHINARDI, PATRICIA; VALENTINUZZI, VERONICA S.; ODA, GISELE A.

Frontiers in Physiology

Frontiers Media S.A.

Lugar: Lausanne; Año: 2021 vol. 12

Living organisms anticipate the seasons by tracking the proportion of light and darknesshours within a day?photoperiod. The limits of photoperiod measurement can beinvestigated in the subterranean rodents tuco-tucos (Ctenomys aff. knighti), whichinhabit dark underground tunnels. Their exposure to light is sporadic and, remarkably,results from their own behavior of surface emergence. Thus, we investigated theendogenous and exogenous regulation of this behavior and its consequences tophotoperiod measurement. In the field, animals carrying biologgers displayed seasonalpatterns of daily surface emergence, exogenously modulated by temperature. In thelaboratory, experiments with constant lighting conditions revealed the endogenousregulation of seasonal activity by the circadian clock, which has a multi-oscillatorystructure. Finally, mathematical modeling corroborated that tuco-tuco?s light exposureacross the seasons is sufficient for photoperiod encoding. Together, our resultselucidate the interrelationship between the circadian clock and temperature in shapingseasonal light exposure patterns that convey photoperiod information in an extremephotic environment.