Circadian Function in the Photoperiodic Induction of Gonadotropin Secretion in the White-crowned Sparrow, Zonotrichia leucophrys gambelii
- 1 May 1974
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 71 (5), 1666-1669
- https://doi.org/10.1073/pnas.71.5.1666
Abstract
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.Keywords
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