Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
In vivo disruption of Xenopus CLOCK in the retinal photoreceptor cells abolishes circadian melatonin rhythmicity without affecting its production levels.
Hayasaka N
,
LaRue SI
,
Green CB
.
???displayArticle.abstract???
Xenopus laevis retinas, like retinas from all vertebrate classes, have endogenous circadian clocks that control many aspects of normal retinal physiology occurring in cells throughout all layers of the retina. The localization of the clock(s) that controls these various rhythms remains unclear. One of the best studied rhythmic events is the nocturnal release of melatonin. Photoreceptor layers can synthesize rhythmic melatonin when these cells are in isolation. However, within the intact retina, melatonin is controlled in a complex way, indicating that signals from many parts of the retina may contribute to the production of melatonin rhythmicity. To test this hypothesis, we generated transgenic tadpoles that express different levels of a dominant negative Xenopus CLOCK specifically in the retinal photoreceptors. Eyes from these tadpoles continued to produce melatonin at normal levels, but with greatly disrupted rhythmicity, the severity of which correlated with the transgene expression level. These results demonstrate that although many things contribute to melatonin production in vivo, the circadian clock localized in the retinal photoreceptors is necessary for its rhythmicity. Furthermore, these data show that the control of the level of melatonin synthesis is separable from the control of its rhythmicity and may be controlled by different molecular machinery. This type of specific "molecular lesion" allows perturbation of the clock in intact tissues and is valuable for dissection of clock control of tissue-level processes in this and other complex systems.
,
,
Pubmed
Anderson,
Symphony of rhythms in the Xenopus laevis retina.
2000,
Pubmed
,
Xenbase
Antoch,
Functional identification of the mouse circadian Clock gene by transgenic BAC rescue.
1997,
Pubmed
Bae,
Circadian regulation of a Drosophila homolog of the mammalian Clock gene: PER and TIM function as positive regulators.
1998,
Pubmed
Besharse,
Circadian clock in Xenopus eye controlling retinal serotonin N-acetyltransferase.
,
Pubmed
,
Xenbase
Boatright,
Regulation of endogenous dopamine release in amphibian retina by melatonin: the role of GABA.
1994,
Pubmed
,
Xenbase
Boatright,
The 5' flanking regions of IRBP and arrestin have promoter activity in primary embryonic chicken retina cell cultures.
1997,
Pubmed
Bunger,
Mop3 is an essential component of the master circadian pacemaker in mammals.
2000,
Pubmed
Cahill,
Circadian clock functions localized in xenopus retinal photoreceptors.
1993,
Pubmed
,
Xenbase
Cahill,
Rhythmic regulation of retinal melatonin: metabolic pathways, neurochemical mechanisms, and the ocular circadian clock.
1991,
Pubmed
,
Xenbase
Cahill,
Circadian regulation of melatonin in the retina of Xenopus laevis: limitation by serotonin availability.
1990,
Pubmed
,
Xenbase
Chong,
Characterization of the chicken serotonin N-acetyltransferase gene. Activation via clock gene heterodimer/E box interaction.
2000,
Pubmed
Chong,
Circadian expression of tryptophan hydroxylase mRNA in the chicken retina.
1998,
Pubmed
,
Xenbase
Damiola,
Restricted feeding uncouples circadian oscillators in peripheral tissues from the central pacemaker in the suprachiasmatic nucleus.
2000,
Pubmed
Darlington,
Closing the circadian loop: CLOCK-induced transcription of its own inhibitors per and tim.
1998,
Pubmed
Dunlap,
Molecular bases for circadian clocks.
1999,
Pubmed
Fain,
Photoreceptor degeneration in vitamin A deprivation and retinitis pigmentosa: the equivalent light hypothesis.
1993,
Pubmed
Gekakis,
Role of the CLOCK protein in the mammalian circadian mechanism.
1998,
Pubmed
Glossop,
Interlocked feedback loops within the Drosophila circadian oscillator.
1999,
Pubmed
Green,
Tryptophan hydroxylase mRNA levels are regulated by the circadian clock, temperature, and cAMP in chick pineal cells.
1996,
Pubmed
Green,
Ontogeny of circadian and light regulation of melatonin release in Xenopus laevis embryos.
1999,
Pubmed
,
Xenbase
Hida,
The human and mouse Period1 genes: five well-conserved E-boxes additively contribute to the enhancement of mPer1 transcription.
2000,
Pubmed
Iuvone,
Dopamine receptor-mediated inhibition of serotonin N-acetyltransferase activity in retina.
1986,
Pubmed
,
Xenbase
Jin,
A molecular mechanism regulating rhythmic output from the suprachiasmatic circadian clock.
1999,
Pubmed
King,
Positional cloning of the mouse circadian clock gene.
1997,
Pubmed
Klein,
The melatonin rhythm-generating enzyme: molecular regulation of serotonin N-acetyltransferase in the pineal gland.
1997,
Pubmed
Kroll,
Transgenic Xenopus embryos from sperm nuclear transplantations reveal FGF signaling requirements during gastrulation.
1996,
Pubmed
,
Xenbase
Lee,
The Drosophila CLOCK protein undergoes daily rhythms in abundance, phosphorylation, and interactions with the PER-TIM complex.
1998,
Pubmed
Park,
Differential regulation of circadian pacemaker output by separate clock genes in Drosophila.
2000,
Pubmed
Plautz,
Quantitative analysis of Drosophila period gene transcription in living animals.
1997,
Pubmed
Rollag,
Radioimmunoassay of serum concentrations of melatonin in sheep exposed to different lighting regimens.
1976,
Pubmed
Rutila,
CYCLE is a second bHLH-PAS clock protein essential for circadian rhythmicity and transcription of Drosophila period and timeless.
1998,
Pubmed
Stokkan,
Entrainment of the circadian clock in the liver by feeding.
2001,
Pubmed
Vitaterna,
Mutagenesis and mapping of a mouse gene, Clock, essential for circadian behavior.
1994,
Pubmed
Zatz,
Light and norepinephrine similarly prevent damping of the melatonin rhythm in cultured chick pineal cells: regulation of coupling between the pacemaker and overt rhythms?
1991,
Pubmed
Zhu,
Three cryptochromes are rhythmically expressed in Xenopus laevis retinal photoreceptors.
2001,
Pubmed
,
Xenbase
Zhu,
The Xenopus clock gene is constitutively expressed in retinal photoreceptors.
2000,
Pubmed
,
Xenbase
