Marlow P B, Mizell S
J Natl Cancer Inst. 1976 Nov;57(5):1069-76. doi: 10.1093/jnci/57.5.1069.
Kidneys were studied from 1,111 leopard frogs (Rana pipiens) after exposures to a 12-hour light-12-hour dark environment. Circadian mitotic rhythms were observed in cells of normal and spontaneous adenocarcinomatous proximal convoluted tubules from these animals. Student's t-tests verified the existence of two distinct cell populations, normal and adenocarcinomatous, in the proximal tubules. Both the mitotic variations and the t-test values were significant with P values of 0.05 or less. Mean mitotic values for the normal and spontaneous adenocarcinomatous proximal tubule epithelia were generally lower during the light-phase and higher during the dark-phase periods of the control day. The mitotic rhythm of the cancerous epithelium was almost always superimposable in outline over that of the normal epithelium during the same experimental period; i.e., the correspondence of phases of the normal and cancerous mitoses was almost identical in a single graph, although the amplitude of the cancerous mitoses was always higher. In addition to the reproducible circadian rhythms, the data demonstrated evidence for the existence of ultradian, as well as circannual rhythms.
在暴露于12小时光照 - 12小时黑暗环境后，对1111只豹蛙（北美豹蛙）的肾脏进行了研究。在这些动物正常的和自发腺癌性的近端曲管细胞中观察到昼夜有丝分裂节律。学生t检验证实了近端小管中存在两种不同的细胞群体，即正常细胞和腺癌性细胞。有丝分裂变化和t检验值均具有显著性，P值小于或等于0.05。在对照日的光照期，正常的和自发腺癌性近端小管上皮细胞的平均有丝分裂值通常较低，而在黑暗期较高。在同一实验期间，癌性上皮细胞的有丝分裂节律在轮廓上几乎总是与正常上皮细胞的有丝分裂节律重叠；也就是说，在单个图表中，正常和癌性有丝分裂的阶段对应几乎相同，尽管癌性有丝分裂的幅度总是更高。除了可重复的昼夜节律外，数据还证明了超日节律以及年节律的存在。
