Project description:Background. The transcriptional circuits of circadian clocks control physiological; and behavioral rhythms. Light may affect such overt rhythms in two ways: (1) by; entraining the clock circuits and (2) via clock-independent molecular pathways. In; this study we examine the relationship between autonomous transcript; oscillations and light-driven transcript responses; Methodology/Principal Findings. Transcript profiles of wild-type and arrhythmic; mutant Drosophila were recorded both in the presence of an environmental; photocycle and in constant darkness. Systematic autonomous oscillations in the; 12-48 hr period range were detectable only in wild-type flies and occurred; preferentially at the circadian period length. However, an extensive program of; light-driven expression was confirmed in arrhythmic mutant flies. Many lightresponsive; transcripts are preferentially expressed in the adult compound eye; and the phospholipase C component of phototransduction, NO RECEPTOR; POTENTIAL (NORPA), is required for their light-dependent regulation. Conclusions/Significance. Although there is growing evidence for the existence; of multiple molecular clock circuits in plants and fungi, Drosophila appears to; possess only one such system. The sustained photic expression responses; identified here are partially coupled to the circadian clock and may reflect a; mechanism for flies to modulate functions such as visual sensitivity and synaptic; transmission in response to seasonal changes in photoperiod. Experiment Overall Design: y w; tim01 flies that had been kept in a 12-hr light/ 12-hr dark cycle for three days were harvested every four hours during an additional light/dark day (ZT) and a subsequent day in constant darkness (CT). Relative to Zeitgeber time 0 (ZT0) as the time of lights on Experiment Overall Design: during the LD cycle and Circadian time 0 (CT0) as the time corresponding to Experiment Overall Design: subjective lights-on during freerun in DD, time courses were collected in a ZT2- Experiment Overall Design: ZT6-ZT10-ZT14-ZT18-ZT22-CT2-CT6-CT10-CT14-CT18-CT22 schedule. Heads Experiment Overall Design: were isolated by breaking up frozen flies and passing them through a set of Experiment Overall Design: sieves. RNA was prepared using guanidine-thiocyanate extraction followed by Experiment Overall Design: purification over a CsCl gradient. Additional purification of the RNA samples was Experiment Overall Design: achieved by applying them to Rneasy columns (Qiagen). Biotin-labeled cRNA Experiment Overall Design: probe was generated from 25 Î¼g of purified RNA and hybridized as described Experiment Overall Design: previously (Wijnen H, Naef F, and Young MW, Methods Enzymol. 2005; 393: 341-365). Experiment Overall Design: For more information see also http://biorhythm.rockefeller.edu

Project description:Background. The transcriptional circuits of circadian clocks control physiological; and behavioral rhythms. Light may affect such overt rhythms in two ways: (1) by; entraining the clock circuits and (2) via clock-independent molecular pathways. In; this study we examine the relationship between autonomous transcript; oscillations and light-driven transcript responses; Methodology/Principal Findings. Transcript profiles of wild-type and arrhythmic; mutant Drosophila were recorded both in the presence of an environmental; photocycle and in constant darkness. Systematic autonomous oscillations in the; 12-48 hr period range were detectable only in wild-type flies and occurred; preferentially at the circadian period length. However, an extensive program of; light-driven expression was confirmed in arrhythmic mutant flies. Many lightresponsive; transcripts are preferentially expressed in the adult compound eye; and the phospholipase C component of phototransduction, NO RECEPTOR; POTENTIAL (NORPA), is required for their light-dependent regulation. Conclusions/Significance. Although there is growing evidence for the existence; of multiple molecular clock circuits in plants and fungi, Drosophila appears to; possess only one such system. The sustained photic expression responses; identified here are partially coupled to the circadian clock and may reflect a; mechanism for flies to modulate functions such as visual sensitivity and synaptic; transmission in response to seasonal changes in photoperiod. For more information see also http://biorhythm.rockefeller.edu. Experiment Overall Design: y w flies that had been kept in a 12-hr light/ 12-hr dark cycle for three days were harvested every four hours during an additional light/dark day (ZT) and a subsequent day in constant darkness (CT). Relative to Zeitgeber time 0 (ZT0) as the time of lights on Experiment Overall Design: during the LD cycle and Circadian time 0 (CT0) as the time corresponding to Experiment Overall Design: subjective lights-on during freerun in DD, time courses were collected in a ZT2- Experiment Overall Design: ZT6-ZT10-ZT14-ZT18-ZT22-CT2-CT6-CT10-CT14-CT18-CT22 schedule. Heads Experiment Overall Design: were isolated by breaking up frozen flies and passing them through a set of Experiment Overall Design: sieves. RNA was prepared using guanidine-thiocyanate extraction followed by Experiment Overall Design: purification over a CsCl gradient. Additional purification of the RNA samples was Experiment Overall Design: achieved by applying them to Rneasy columns (Qiagen). Biotin-labeled cRNA Experiment Overall Design: probe was generated from 25 Î¼g of purified RNA and hybridized as described Experiment Overall Design: previously (Wijnen H, Naef F, and Young MW, Methods Enzymol. 2005; 393: 341-365). Experiment Overall Design: For more information see also http://biorhythm.rockefeller.edu

Project description:Background. The transcriptional circuits of circadian clocks control physiological; and behavioral rhythms. Light may affect such overt rhythms in two ways: (1) by; entraining the clock circuits and (2) via clock-independent molecular pathways. In; this study we examine the relationship between autonomous transcript; oscillations and light-driven transcript responses; Methodology/Principal Findings. Transcript profiles of wild-type and arrhythmic; mutant Drosophila were recorded both in the presence of an environmental; photocycle and in constant darkness. Systematic autonomous oscillations in the; 12-48 hr period range were detectable only in wild-type flies and occurred; preferentially at the circadian period length. However, an extensive program of; light-driven expression was confirmed in arrhythmic mutant flies. Many lightresponsive; transcripts are preferentially expressed in the adult compound eye; and the phospholipase C component of phototransduction, NO RECEPTOR; POTENTIAL (NORPA), is required for their light-dependent regulation. Conclusions/Significance. Although there is growing evidence for the existence; of multiple molecular clock circuits in plants and fungi, Drosophila appears to; possess only one such system. The sustained photic expression responses; identified here are partially coupled to the circadian clock and may reflect a; mechanism for flies to modulate functions such as visual sensitivity and synaptic; transmission in response to seasonal changes in photoperiod. Experiment Overall Design: y w; tim01 flies that had been kept in a 12-hr light/ 12-hr dark cycle for three days were harvested every four hours during an additional light/dark day (ZT) and a subsequent day in constant darkness (CT). Relative to Zeitgeber time 0 (ZT0) as the time of lights on Experiment Overall Design: during the LD cycle and Circadian time 0 (CT0) as the time corresponding to Experiment Overall Design: subjective lights-on during freerun in DD, time courses were collected in a ZT2- Experiment Overall Design: ZT6-ZT10-ZT14-ZT18-ZT22-CT2-CT6-CT10-CT14-CT18-CT22 schedule. Heads Experiment Overall Design: were isolated by breaking up frozen flies and passing them through a set of Experiment Overall Design: sieves. RNA was prepared using guanidine-thiocyanate extraction followed by Experiment Overall Design: purification over a CsCl gradient. Additional purification of the RNA samples was Experiment Overall Design: achieved by applying them to Rneasy columns (Qiagen). Biotin-labeled cRNA Experiment Overall Design: probe was generated from 25 Î¼g of purified RNA and hybridized as described Experiment Overall Design: previously (Wijnen H, Naef F, and Young MW, Methods Enzymol. 2005; 393: 341-365). Experiment Overall Design: For more information see also http://biorhythm.rockefeller.edu

Dataset Information

Transcription profiling of Arabidopsis to identify of circadian-regulated genes

Publications

The circadian clock regulates auxin signaling and responses in Arabidopsis.

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