Prichard R G, Lickey M E
J Neurosci. 1981 Aug;1(8):835-9. doi: 10.1523/JNEUROSCI.01-08-00835.1981.
A transition from constant light (LL) to constant darkness (DD) will reset the circadian rhythms of most organisms to a phase that normally occurs near dusk. We tested the circadian oscillator in the Aplysia eye for this property. The test was run in vitro under two conditions. Using the two eyes of a single animal, one eye was left attached to the cerebral ganglion by its intact optic nerve and the other was detached by cutting its nerve. The amount of LL preceding LL/DD was the independent variable; the phase of the two eyes was the measured variable. When LL less than 12 hr, neither the cut nor the attached eye was reset by LL/DD. When 12 less than or equal to LL less than or equal to 24 hr, the attached eye was reset but the detached eye was not. Thus, for these durations of LL, resetting by LL/DD was found to be dependent on the integrity of optic nerve. When LL was about 21 hr, the differential response of the two eyes caused them to be about 12 hr out of phase. When LL was between 27 and 75 hr, LL/DD reset both eyes but there was a low amplitude cyclic modulation of about +/- 3 hr in the phase to which they were reset by LL/DD. This modulation shows that LL did not stop the eye clock but rather that LL/DD reset its phase while it was free running in LL.
从持续光照（LL）过渡到持续黑暗（DD）会将大多数生物体的昼夜节律重置到通常在黄昏附近出现的相位。我们针对这一特性测试了海兔眼睛中的昼夜振荡器。该测试在两种条件下进行体外实验。使用单只动物的两只眼睛，一只眼睛通过完整的视神经与脑神经节相连，另一只眼睛则通过切断其神经使其分离。LL之前的LL时长是自变量；两只眼睛的相位是测量变量。当LL时长小于12小时时，LL/DD对切断神经的眼睛和相连的眼睛均未产生重置作用。当12≤LL≤24小时时，相连的眼睛被重置，但切断神经的眼睛未被重置。因此，对于这些LL时长，发现LL/DD的重置作用依赖于视神经的完整性。当LL时长约为21小时时，两只眼睛的不同反应导致它们的相位相差约12小时。当LL时长在27至75小时之间时，LL/DD重置了两只眼睛，但它们被LL/DD重置到的相位存在约±3小时的低幅度周期性调制。这种调制表明LL并未使眼睛的生物钟停止，而是在眼睛在LL中自由运行时，LL/DD重置了其相位。
