Abstract
Circadian rhythms are entrained by light to follow the daily solar cycle. We show that Drosophila uses at least three light input pathways for this entrainment: (1) cryptochrome, acting in the pacemaker cells themselves, (2) the compound eyes, and (3) extraocular photoreception, possibly involving an internal structure known as the Hofbauer-Buchner eyelet, which is located underneath the compound eye and projects to the pacemaker center in the brain. Although influencing the circadian system in different ways, each input pathway appears capable of entraining circadian rhythms at the molecular and behavioral level. This entrainment is completely abolished in glass(60j) cry(b) double mutants, which lack all known external and internal eye structures in addition to being devoid of cryptochrome.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Biological Clocks / physiology*
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Blindness / genetics*
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Blindness / metabolism
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Blindness / physiopathology
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Brain / metabolism
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Brain / pathology
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Brain / physiopathology
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Circadian Rhythm / physiology*
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Cryptochromes
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Drosophila Proteins*
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Drosophila melanogaster / cytology
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Drosophila melanogaster / metabolism*
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Eye / metabolism
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Eye / pathology
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Eye / physiopathology
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Eye Abnormalities / genetics*
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Eye Abnormalities / metabolism
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Eye Abnormalities / physiopathology
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Eye Proteins*
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Flavoproteins / genetics
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Flavoproteins / metabolism
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Light Signal Transduction / genetics*
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Mutation / physiology
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Neurons / metabolism
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Neurons / pathology
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Photic Stimulation
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Photoreceptor Cells, Invertebrate / cytology
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Photoreceptor Cells, Invertebrate / metabolism*
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Receptors, G-Protein-Coupled
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Visual Pathways / abnormalities
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Visual Pathways / metabolism
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Visual Pathways / physiopathology
Substances
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Cryptochromes
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Drosophila Proteins
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Eye Proteins
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Flavoproteins
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Receptors, G-Protein-Coupled
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cry protein, Drosophila