Mathematical modelling approach to photoperiodism in a subterranean rodent

DANILO FLÔRES; VALENTINUZZI, VERÓNICA S.; ODA, GISELE A

Valparaiso

Simposio; XIV Latin American Symposium on Chronobiology-LASC; 2017

Universidad de Valparaiso

Many living organisms adjust their annual physiology to the seasons, by decoding day length from photoperiod, a photic environmental cue that changes consistently along the year. The tuco-tuco (Ctenomys aff. knighti, Rodentia) is a subterranean rodent from the Monte Desert, Argentina, which experiences cold/dry winters and warm/wet summers. We have previously studied the daily light exposure patterns of the species, focusing on the entrainment of their circadian system to the 24-hour day. Extending these measurements to a yearly scale, we will now study if and how tuco-tucos use photoperiod to time their physiology along the year. In a first approach, mathematical modelling will be employed to simulate the tuco-tuco?s circadian oscillators and their response to different light regimens. Previous works indicate that tuco-tucos possess two oscillators controlling circadian rhythms and we hypothesize that these oscillators could be used as the basis for photoperiod reading, based on a mechanism of internal coincidence. To test this hypothesis, we will simulate a system of two coupled limit-cycle Pavlidis-Pittendrigh oscillators, exposed to different skeleton photoperiods and to the light-exposure patterns experienced by tuco-tucos throughout the year. Here, we present preliminary data to be used as a starting point. Before advancing to a complete model, we started by verifying the dynamics of a single oscillator, subjected to skeleton photoperiods, with photophases of different durations. Predictions based on the Phase Response Curve matched most of the results obtained. Having explored the limitations of a single oscillator, we will next analyze the responses of two coupled oscillators.