The circadian clock of fruit flies is blind after elimination of all known photoreceptors.
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.
Helfrich-Förster
C
C
Zoologisches Institut, Tierphysiologie, Universität Tübingen, Auf der Morgenstelle 28, D-72076, Tübingen, Germany.
Winter
C
C
Hofbauer
A
A
Hall
J C
JC
Stanewsky
R
R
D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D001766:Blindness / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D002940:Circadian Rhythm / Q000502:physiology*; D056931:Cryptochromes; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000166:cytology / Q000378:metabolism*; D005123:Eye / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D005124:Eye Abnormalities / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D005136:Eye Proteins; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism; D055537:Light Signal Transduction / Q000235:genetics*; D009154:Mutation / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D014795:Visual Pathways / Q000002:abnormalities / Q000378:metabolism / Q000503:physiopathology
D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila