Different circadian oscillators control Ca
            <sup>2+</sup>
            fluxes and
            <i>Lhcb</i>
            gene expression

Sai, Jiqing; Johnson, Carl Hirschie

doi:10.1073/pnas.96.20.11659

Cited by 60 publications

(50 citation statements)

References 24 publications

(37 reference statements)

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“…It is unclear how much circadian timing actually varies among plant tissues and what are the molecular causes of such variation. Differences in circadian period between plant rhythms have been reported (Hennessey and Field, 1992;Millar et al, 1995a;Fowler et al, 1999;Sai and Johnson, 1999). The rhythms in question were not only expressed in different cells but also had overtly unrelated mechanisms (leaf movement and CAB gene expression, for example).…”

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confidence: 95%

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The Circadian Clock That Controls Gene Expression in Arabidopsis Is Tissue Specific

Thain

Murtas

Lynn³

et al. 2002

Plant Physiology

143

118

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The expression of CHALCONE SYNTHASE (CHS) expression is an important control step in the biosynthesis of flavonoids, which are major photoprotectants in plants. CHS transcription is regulated by endogenous programs and in response to environmental signals. Luciferase reporter gene fusions showed that the CHS promoter is controlled by the circadian clock both in roots and in aerial organs of transgenic Arabidopsis plants. The period of rhythmic CHS expression differs from the previously described rhythm of chlorophyll a/b-binding protein (CAB) gene expression, indicating that CHS is controlled by a distinct circadian clock. The difference in period is maintained in the wild-type Arabidopsis accessions tested and in the de-etiolated 1 and timing of CAB expression 1 mutants. These clock-affecting mutations alter the rhythms of both CAB and CHS markers, indicating that a similar (if not identical) circadian clock mechanism controls these rhythms. The distinct tissue distribution of CAB and CHS expression suggests that the properties of the circadian clock differ among plant tissues. Several animal organs also exhibit heterogeneous circadian properties in culture but are believed to be synchronized in vivo. The fact that differing periods are manifest in intact plants supports our proposal that spatially separated copies of the plant circadian clock are at most weakly coupled, if not functionally independent. This autonomy has apparently permitted tissue-specific specialization of circadian timing.Light is a key environmental signal for plants, regulating gene expression and development (Neff et al., 2000). Changes in fluence rate and light quality can occur unpredictably and rapidly during the day but have an underlying day-night cycle. Plants have evolved a circadian timing system that allows the anticipation of this predictable rhythm. When plants are deprived of environmental time cues and placed in constant ("free running") environmental conditions, circadian rhythms persist with a period of around 24 h, often for many days (Millar, 1999; McClung, 2000;Murtas and Millar, 2000;Johnson, 2001). Within the circadian system of the whole organism, the term "circadian oscillator" has been used to denote the parts of the system responsible for rhythm generation. Light-dark signals entrain the oscillator via input phototransduction pathways, synchronizing its phase with the environmental light-dark cycle and also affecting its period. Rhythmic output from the oscillator controls a large number of physiological processes in plants ( Lumsden and Millar, 1998). The abundance of 2% to 6% of RNA transcripts in Arabidopsis plants was scored as circadian-regulated in two recent microarray analyses, for example (Harmer et al., 2000;Schaffer et al., 2001).The rhythmic expression of chlorophyll a/bbinding protein (CAB or Light-Harvesting Complex [LHCB]) genes has often been used as a marker for circadian regulation in plants (for review, see Fejes and Nagy, 1998), especially using firefly (Photinus pyralis) luciferase (LUC) repor...

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confidence: 95%

“…The authors point out that a phase difference could result from tissue-specific clocks or from tissue-specific responses to a single, common clock. Where period differences are observed, the latter interpretation can be ruled out (Sai and Johnson, 1999).…”

Section: Differences In the Circadian Regulation Of Chs And Cabmentioning

confidence: 99%

The Circadian Clock That Controls Gene Expression in Arabidopsis Is Tissue Specific

Thain

Murtas

Lynn³

et al. 2002

Plant Physiology

143

118

View full text Add to dashboard Cite

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“…Wild-type plants maintain circadian rhythms (A) and (B) Seedlings of the C24 parent (fine line), tic (heavy line), elf3-1 (open triangles), and tic elf3-1 (crosses) were grown in standard 12L: 12D conditions. CAB:LUC luminescence was monitored under constant RϩB (as in Figure 1C) (A) or DD (as in Figure 1B) with different periods (Sai and Johnson, 1999;Hall et al, 2002;Michael et al, 2003), indicating a subtle difference in the underlying circadian oscillators. For example, CCR2 expression can have a different period than CAB and CCA1 expression (Eriksson et al, 2003).…”

Section: Tic Affects Rhythmic Markers Differentiallymentioning

confidence: 99%

TheTIME FOR COFFEEGene Maintains the Amplitude and Timing of Arabidopsis Circadian Clocks[W]

et al. 2003

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Plants synchronize developmental and metabolic processes with the earth's 24-h rotation through the integration of circadian rhythms and responses to light. We characterize the time for coffee ( tic ) mutant that disrupts circadian gating, photoperiodism, and multiple circadian rhythms, with differential effects among rhythms. TIC is distinct in physiological functions and genetic map position from other rhythm mutants and their homologous loci. Detailed rhythm analysis shows that the chlorophyll a/b -binding protein gene expression rhythm requires TIC function in the mid to late subjective night, when human activity may require coffee, in contrast to the function of EARLY-FLOWERING3 ( ELF3 ) in the late day to early night. tic mutants misexpress genes that are thought to be critical for circadian timing, consistent with our functional analysis. Thus, we identify TIC as a regulator of the clock gene circuit. In contrast to tic and elf3 single mutants, tic elf3 double mutants are completely arrhythmic. Even the robust circadian clock of plants cannot function with defects at two different phases.

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“…Several lines of evidence point toward the existence of multiple distinct oscillators in cells and/or tissues of organisms contributing to circadian timing. First, there exist free-running rhythms with different period lengths in the same organism (Morse et al 1994;Sai and Johnson 1999;Cambras et al 2007), and there is residual rhythmicity in strains that are defective in known oscillator components (Loros et al 1986;Stanewsky et al 1998;Emery et al 2000;Collins et al 2005). Second, some tissue-specific oscillators are constructed differently from the core oscillators located in the brain (Stanewsky et al 1998;Ivanchenko et al 2001;Krishnan et al 2001;Hardin et al 2003;Collins et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Complexity of theNeurospora crassaCircadian Clock System: Multiple Loops and Oscillators

Paula

Vitalini²,

Gomer³

et al. 2007

Cold Spring Harbor Symposia on Quantitative Biology

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Organisms from bacteria to humans use a circadian clock to control daily biochemical, physiological, and behavioral rhythms. We review evidence from Neurospora crassa that suggests that the circadian clock is organized as a network of genes and proteins that form coupled evening-and morning-specific oscillatory loops that can function automously, respond differently to environmental inputs, and regulate phase-specific outputs. There is also evidence for coupled morning and evening oscillator loops in plants, insects, and mammals, suggesting conservation of clock organization. From a systems perspective, fungi provide a powerful model organism for investigating oscillator complexity, communication between oscillators, and addressing reasons why the system has evolved to be so complex.

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Different circadian oscillators control Ca ²⁺ fluxes and Lhcb gene expression

Cited by 60 publications

References 24 publications

The Circadian Clock That Controls Gene Expression in Arabidopsis Is Tissue Specific

The Circadian Clock That Controls Gene Expression in Arabidopsis Is Tissue Specific

TheTIME FOR COFFEEGene Maintains the Amplitude and Timing of Arabidopsis Circadian Clocks[W]

Complexity of theNeurospora crassaCircadian Clock System: Multiple Loops and Oscillators

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Different circadian oscillators control Ca 2+ fluxes and Lhcb gene expression

Cited by 60 publications

References 24 publications

The Circadian Clock That Controls Gene Expression in Arabidopsis Is Tissue Specific

The Circadian Clock That Controls Gene Expression in Arabidopsis Is Tissue Specific

TheTIME FOR COFFEEGene Maintains the Amplitude and Timing of Arabidopsis Circadian Clocks[W]

Complexity of theNeurospora crassaCircadian Clock System: Multiple Loops and Oscillators

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Different circadian oscillators control Ca ²⁺ fluxes and Lhcb gene expression