Citation
Transplanted Suprachiasmatic Nucleus Determines Circadian Period
TL;DR
SCN transplants transfer circadian period from donor to recipient
This landmark study definitively proved that the suprachiasmatic nucleus (SCN) is the master circadian clock in mammals. By transplanting SCN tissue from mutant hamsters with 20-hour rhythms into normal hamsters with 24-hour rhythms, the researchers showed that recipients completely adopted the donor's circadian period within days.
The finding demonstrated that circadian timing is not distributed throughout the body but centrally controlled by a specific brain region. This has profound implications for understanding jet lag, shift work disorders, and the biological basis of productivity rhythms.
Key Findings from Ralph et al. (1990)
- SCN transplants transfer circadian period from donor to recipient
- Recipients abandon lifelong rhythms and adopt donor's timing within days
- SCN is both necessary and sufficient for circadian rhythm generation