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Coordination of Plant Metabolism and Development by the Circadian Clock.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Kreps, Joel A. Kay, Steve A. |
| Copyright Year | 1997 |
| Abstract | Many plant cellular activities occur with a daily rhythmicity. In some cases, the rhythmicity of these cellular activities is maintained in plants growing under constant environmental conditions, such as continuous light (LL) or darkness (DD) and constant temperature. Because rhythms can persist in the absence of externa1 time cues (known as free-running conditions), they must be driven by an internal oscillator. This oscillator, which is known as the circadian clock, generates circadian rhythms. For the circadian clock to regulate rhythms such that they occur at the correct time of day throughout the year, it must be able to perceive the seasonal changes in day length. This adjustment of the clock is known as entrainment, and the environmental cues that are perceived are called Zeitgebers, from the German word meaning “time giver.” Thus, the circadian clock can be considered to be an internal processor of temporal inputs from the environment (such as light and temperature). Output from the processor regulates the timing of metabolic and developmental events within the plant. Although the molecular basis of the circadian clock in plants is not known, work from other systems has established a transcriptional negative feedback loop as a paradigm. In Drosophila, the clock components encoded by the period (per) and timeless (fim) genes function to regulate negatively their own transcription (Hardin et al., 1990; Sehgal et al., 1995). In this system, the accumulation of PER and TIM proteins eventually leads to the arrest of transcription from the corresponding genes, but how this is achieved is not known (Hunter-Ensor et al., 1996). The TIM protein is unstable in the light, and this photoinstability may be part of the mechanism by which the Drosophila circadian clock entrains to the photoperiod (Myers et al., 1996). A clock gene, Frequency (Frq), has also been isolated from the fungus Neurospora crassa (McClung et al., 1989). As is the case for the clock genes in Drosophila, the Frq gene product also negatively regulates its own transcription (Aronson et al., 1994b), and FRQ protein levels cycle (Dunlap, 1996). Transcription of the Frq gene is upregulated in re- |
| Starting Page | 1235 |
| Ending Page | 1244 |
| Page Count | 10 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.plantcell.org/content/plantcell/9/7/1235.full.pdf |
| PubMed reference number | 12237384v1 |
| Volume Number | 9 |
| Issue Number | 7 |
| Journal | The Plant cell |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Circadian Clocks Circadian Rhythms Fungi Genome Encoded Entity Metabolic Process, Cellular Oscillator Device Component Sleep Disorders, Circadian Rhythm Unstable Medical Device Problem |
| Content Type | Text |
| Resource Type | Article |
