OXYGEN-CONSUMPTION AND BODY-TEMPERATURE RHYTHMS IN THE GOLDEN SPINY MOUSE - RESPONSES TO CHANGES IN DAY LENGTH

The golden spiny mouse Acomys russatus is a rock dwelling rodent which lives in extremely arid and hot habitats. In Israel it is nocturnal e xcept in areas in which it coexists with the common spiny mouse A. cah irinus. In such places it is diurnal. The daily rhythms of body temper ature (T-b) and oxygen consumption (VO2) were compared in mice acclima ted to two different photoperiod regimes in the laboratory: 8L:16D (sh ort day) and 16L:8D (long day) at a constant ambient temperature. The daily rhythms of VO2 and of T-b in A. russatus were found to differ gr eatly under long and short photoperiod. Both parameters peaked at ligh ts-out under both photoperiod regimes. In short day acclimated mice th e effect of transmitter implantation was also studied. VO2 values at n ight were lower after implanting. The results of this study show that T-b and VO2 rhythms are altered by the lighting regimes. Seasonal accl imatization of thermoregulatory mechanisms in the golden spiny mouse a re partly induced by changes in photoperiodicity.