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Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters
Published on: September 27, 2012
Hypothalamic circadian organization in birds. II. Clock gene expression
Ute Abraham1, Urs Albrecht, Roland Brandstätter
1Max-Planck Research Centre for Ornithology, Andechs, Germany.
Chronobiology International
|August 15, 2003
Summary
In house sparrows, circadian clock gene Per2 is expressed in two hypothalamic nuclei, the suprachiasmatic nucleus (SCN) and lateral hypothalamic nucleus (LHN), indicating complex avian hypothalamic organization. These rhythms are autonomous, not driven by the pineal gland, but influenced by melatonin.
Area of Science:
- Neuroscience
- Chronobiology
- Avian Biology
Background:
- The suprachiasmatic nucleus (SCN) is the primary mammalian circadian pacemaker.
- Hypothalamic circadian organization in birds remains poorly understood.
- Clock gene expression patterns offer insights into circadian regulation.
Purpose of the Study:
- To investigate hypothalamic circadian organization in birds, specifically focusing on Per2 gene expression in the house sparrow.
- To compare avian hypothalamic circadian patterns with those in mammals.
- To determine the influence of the pineal gland on hypothalamic circadian rhythms.
Main Methods:
- Review of recent findings on clock gene expression in bird hypothalami.
- Focus on circadian Per2 expression analysis in the house sparrow.
- Examination of Per2 expression in pinealectomized house sparrows.
Main Results:
- Rhythmic Per2 gene expression in house sparrow hypothalamus occurs in two distinct nuclei: the SCN and the lateral hypothalamic nucleus (LHN).
- Per2 expression exhibits complex temporal and spatial distribution, suggesting SCN compartmentalization.
- Circadian Per2 expression patterns persist in pinealectomized birds, indicating autonomous hypothalamic oscillators.
- Pineal melatonin rhythm influences the phase and amplitude of hypothalamic Per2 expression.
Conclusions:
- Avian hypothalamic circadian organization is more complex than previously thought, involving multiple nuclei.
- Hypothalamic circadian rhythms in house sparrows are generated by autonomous oscillators.
- The pineal gland, while not the primary driver, modulates hypothalamic circadian rhythms through melatonin.
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