Per1 mutation enhances masking responses in mice

Light can restrict the activity of an animal to a diurnal or nocturnal niche by synchronizing its endogenous clock (entrainment) which controls the sleep wake cycle. Light can also directly change an animal’s activity level (masking). In mice, high illumination levels decrease activity, i.e. negative masking occurs. To investigate the role of core circadian clock genes Per1 and Per2 in masking, we used a 5-day behavioral masking protocol consisting of 3 h pulses of light given in the night at various illuminances (4–5 lux, 20 lux and 200 lux). Mice lacking the Per1 gene had decreased locomotion in the presence of a light pulse compared to wild-type, Per2 and Per1 Per2 double mutant mice. Per2 single mutant and Per1 Per2 double mutant mice did not show significantly different masking responses compared to wild-type controls. This suggests that Per1 suppresses negative masking responses in mice.

光能通过同步动物体内的内源性时钟（同步化作用），从而控制其睡眠-觉醒周期，进而限制动物的活动范围至日间或夜间生态位。此外，光还能直接影响动物的活动水平（遮蔽效应）。在老鼠的实验中，高照度水平会降低其活动，即发生负向遮蔽效应。为探究核心昼夜节律时钟基因Per1和Per2在遮蔽效应中的作用，我们采用了一项为期5天的行为遮蔽实验方案，该方案包括在夜间以不同照度（4-5 lux、20 lux和200 lux）提供3小时的脉冲光照。与野生型、Per2和Per1 Per2双重突变型老鼠相比，缺乏Per1基因的老鼠在光脉冲存在的情况下，运动活动显著减少。与野生型对照组相比，Per2单突变型和Per1 Per2双重突变型老鼠未表现出显著不同的遮蔽效应。这表明Per1基因能够抑制老鼠的负向遮蔽反应。