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Science 8 September 1967:
Vol. 157. no. 3793, pp. 1182 - 1185
DOI: 10.1126/science.157.3793.1182
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Articles

Circadian Clock in Photoperiodic Time Measurement: A Test of the Bünning Hypothesis

Michael Menaker 1 and Arnold Eskin 1

1 Department of Zoology, University of Texas, Austin 78712

A technique has been developed for effectively separating the direct inductive effect of a light signal from its effect on the phase of the rhythm of sensitivity to photoperiodic induction. With this technique it has been shown that a 75-minute pulse of light per day, when appropriately positioned with respect to the circadian activity cycle of the sparrow Passer domesticus, is sufficient to produce a response normally produced only by long days. The results cannot be interpreted in terms of a requirement of an absolute amount of either darkness or light and offer strong confirmation of Bünning's hypothesis concerning the mechanism of photoperiodic time measurement.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Regulation of Testis Function in Golden Hamsters: A Circadian Clock Measures Photoperiodic Time.
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