Follett B K, Mattocks P W, Farner D S
Proc Natl Acad Sci U S A. 1974 May;71(5):1666-9. doi: 10.1073/pnas.71.5.1666.
Photosensitive White-crowned Sparrows (Zonotrichia leucophrys gambelii) previously maintained on short day lengths (8-hr light; 16-hr darkness) were transferred to complete darkness. At various intervals thereafter (2-100 hr) they were exposed to a single 8-hr light period. To determine if the light period had been inductive, plasma luteinizing-hormone concentration was measured by radioimmunoassay in blood samples taken before and after the light period. Inductive light periods recurred at approximately daily intervals. The data provide further evidence for the involvement of a circadian rhythm in time measurement in the photoperiodic responses of birds.
先前饲养在短日照（8小时光照；16小时黑暗）条件下的光敏白冠雀（Zonotrichia leucophrys gambelii）被转移到完全黑暗的环境中。此后在不同的时间间隔（2 - 100小时），它们被暴露在一个8小时的光照期。为了确定光照期是否具有诱导性，通过放射免疫分析法在光照期前后采集的血样中测量血浆促黄体生成素浓度。诱导性光照期大约每隔一天重复出现一次。这些数据为昼夜节律参与鸟类光周期反应的时间测量提供了进一步的证据。
