Schumann Desiree M, Cooper Howard M, Hofmeyr Margaretha D, Bennett Nigel C
Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, South Africa.
Physiol Behav. 2005 Jun 30;85(3):231-9. doi: 10.1016/j.physbeh.2005.03.024.
Although humans are diurnal in behaviour, animal models used for the study of circadian rhythms are mainly restricted to nocturnal rodents. This study focussed on the circadian behaviour of a rodent from South Africa that has a preference for daylight, the four-striped field mouse, Rhabdomys pumilio. In order to characterise the behavioural pattern of daily activity, locomotor rhythms were studied under different light regimes using an automated data recording system. Under conditions of natural daylight, which include dawn and dusk transitions, R. pumilio exhibited activity restricted to the daytime period. Activity was concentrated around morning and evening with a decrease during mid-day. A similar diurnal preference pattern of behaviour was recorded under a light-dark cycle of artificial illumination. Under conditions of constant darkness, the four-striped field mouse exhibited a free-running circadian rhythm of locomotor activity with activity concentrated during the subjective day. Free-running rhythms varied greatly between individuals, from slightly less to slightly more than 24 h (range = 23.10 to 24.80 h). Under conditions of constant light, the mice were more active during subjective day, but the free-running rhythm in all individuals was consistently longer than 24 h (range = 24.30 to 24.79 h).
尽管人类在行为上是昼行性的，但用于昼夜节律研究的动物模型主要局限于夜行性啮齿动物。本研究聚焦于一种来自南非、偏好日光的啮齿动物——四线野鼠（Rhabdomys pumilio）的昼夜行为。为了描述日常活动的行为模式，使用自动数据记录系统在不同光照条件下研究了运动节律。在包括黎明和黄昏过渡的自然日光条件下，四线野鼠的活动仅限于白天。活动集中在上午和傍晚，中午减少。在人工照明的明暗循环条件下，记录到了类似的昼行性偏好行为模式。在持续黑暗条件下，四线野鼠表现出自由运行的运动活动昼夜节律，活动集中在主观白天。个体之间的自由运行节律差异很大，从略少于24小时到略多于24小时（范围 = 23.10至24.80小时）。在持续光照条件下，小鼠在主观白天更活跃，但所有个体的自由运行节律始终长于24小时（范围 = 24.30至24.79小时）。
