DeCoursey P J, Krulas J R, Mele G, Holley D C
Department of Biological Sciences, University of South Carolina, Columbia 29208, USA.
Physiol Behav. 1997 Nov;62(5):1099-108. doi: 10.1016/s0031-9384(97)00263-1.
Circadian activity parameters of 53 white-tailed antelope ground squirrels, Ammospermophilus leucurus, were measured to determine the role of the suprachiasmatic nuclei (SCN) pacemaker in their health and survival. Wheel-running activity was monitored in the laboratory with 44 individuals to document the presence of free-running circadian rhythms and ability to entrain to light-dark cycles. Twenty-two individuals were returned to the desert site of origin, including 12 intact control animals and 10 animals whose circadian timing had been disrupted by SCN-lesioning. Time of activity was recorded continuously for 15 days in a large outdoor enclosure by a motion detector, a microchip transponder detector, and video surveillance. An unplanned nighttime attack by a feral cat resulted in the death of 60% of the SCN-lesioned animals and 29% of the control animals in the enclosure. Surface activity of SCN-lesioned animals at the food cache occurred both in daytime and at night, ranging from 16.0% nighttime activity for one partially lesioned individual to 52.1% for one completely lesioned animal. Controls were strongly day-active, with nighttime surface trips constituting only 0-1.3% of all excursions to the cache. Nine wild free-ranging individuals, including one with a radiotransmitter collar, were exclusively day-active. One of the functions of the SCN in mammals may be to reduce activity of animals during times that are unfavorable for activity.
测量了53只白尾羚羊地松鼠（Ammospermophilus leucurus）的昼夜活动参数，以确定视交叉上核（SCN）起搏器在其健康和生存中的作用。在实验室中对44只个体的转轮活动进行监测，以记录自由运行的昼夜节律的存在以及对明暗周期的同步能力。22只个体被放回原产地沙漠，其中包括12只完整的对照动物和10只昼夜节律因SCN损伤而被破坏的动物。通过运动探测器、微芯片应答器探测器和视频监控，在一个大型户外围栏中连续15天记录活动时间。一只野猫的意外夜间袭击导致围栏中60%的SCN损伤动物和29%的对照动物死亡。SCN损伤动物在食物储存处的地面活动在白天和夜间都有发生，范围从一只部分损伤个体的16.0%夜间活动到一只完全损伤动物的52.1%。对照动物强烈地在白天活动，夜间到储存处的地面出行仅占所有出行的0 - 1.3%。9只野生自由放养个体，包括一只佩戴无线电发射器项圈的个体，只在白天活动。SCN在哺乳动物中的功能之一可能是在不利于活动的时间减少动物的活动。
