Start the clock! Circadian rhythms and development

Vallone, Daniela; Lahiri, Kajori; Dickmeis, Thomas; Foulkes, Nicholas S.

doi:10.1002/dvdy.20998

Cited by 69 publications

(62 citation statements)

References 145 publications

(179 reference statements)

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“…Biological rhythms such as in gene expression, physiology, and behavior have developed as a direct consequence of rhythmic sequences of light (day) and darkness (night) imposed by the rotation of the Earth (Menaker et al 1978;Dunlap 1999;Hardin 2005;Vallone et al 2007). As a rule, circadian rhythms (biological rhythms of approximately 24 h) persist, even in constant darkness, because they are controlled by an endogenous mechanism known as the "biological clock" (Helfrich-Förster 2002).…”

Section: Circadian Plasticity As a New Type Of Neuronal Plasticitymentioning

confidence: 99%

Circadian rhythms in the morphology of neurons in Drosophila

Mehnert

Cantera

2011

Cell Tissue Res

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Neurons have an enormous capacity to adapt to changing conditions through the regulation of gene expression, morphology, and physiology. In the fruit fly Drosophila melanogaster, this plasticity includes recurrent changes taking place within intervals of a few hours during the day. The rhythmic alterations in the morphology of neurons described so far include changes in axonal diameter, branching complexity, synapse numbers, and the number of synaptic vesicles. The cycles of these changes have larger amplitude when the fly is exposed to light, but they persist in constant darkness and require the expression of the clock genes period and timeless, leading to the concept of circadian plasticity. The molecular mechanisms driving these cycles appear to require the expression of these genes either inside the neurons themselves or in other peripheral pacemaker cells. Loss-of-function mutations in period and timeless not only abolish the morphological rhythms, but also often cause abnormal axonal branching suggesting that circadian plasticity is relevant for the maintenance of normal morphology. Research into whether (1) circadian plasticity is a common feature of neurons in all animals and (2) our own neurons change shape between day and night will be of interest.

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Section: Circadian Plasticity As a New Type Of Neuronal Plasticitymentioning

confidence: 99%

Circadian rhythms in the morphology of neurons in Drosophila

Mehnert

Cantera

2011

Cell Tissue Res

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“…Rhythms of cell proliferation are evident from cyanobacteria to humans (Bjarnason & Jordan 2000, Mori & Johnson 2000, and several cell cycle genes have been shown to be under transcriptional control by circadian clock factors (Reddy et al 2005, Hunt & Sassone-Corsi 2007, Vallone et al 2007. Our recent study in zebrafish larvae has indicated a role for glucocorticoids in the regulation of these rhythms (Dickmeis et al 2007). Circadian cell cycle rhythms are present both in the larvae and in zebrafish-derived cell lines, implying a cell-autonomous clock regulation also in this species (Dekens et al 2003).…”

Section: Glucocorticoids and Circadian Cell Cycle Rhythmsmentioning

confidence: 99%

“…Circadian cell cycle rhythms are present both in the larvae and in zebrafish-derived cell lines, implying a cell-autonomous clock regulation also in this species (Dekens et al 2003). However, the examination of pituitary mutant larvae revealed that, in vivo, the rhythms depend on systemic input from this gland (Dickmeis et al 2007). Analysis of mutants with overlapping pituitary cell type deficiencies pinpointed the corticotrope lineage as the source for the required signal.…”

Section: Glucocorticoids and Circadian Cell Cycle Rhythmsmentioning

confidence: 99%

Glucocorticoids and the circadian clock

Dickmeis¹

2008

Journal of Endocrinology

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418

292

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Glucocorticoids, hormones produced by the adrenal gland cortex, perform numerous functions in body homeostasis and the response of the organism to external stressors. One striking feature of their regulation is a diurnal release pattern, with peak levels linked to the start of the activity phase. This release is under control of the circadian clock, an endogenous biological timekeeper that acts to prepare the organism for daily changes in its environment. Circadian control of glucocorticoid production and secretion involves a central pacemaker in the hypothalamus, the suprachiasmatic nucleus, as well as a circadian clock in the adrenal gland itself. Central circadian regulation is mediated via the hypothalamic-pituitary-adrenal axis and the autonomic nervous system, while the adrenal gland clock appears to control sensitivity of the gland to the adrenocorticopic hormone (ACTH). The rhythmically released glucocorticoids in turn might contribute to synchronisation of the cell-autonomous clocks in the body and interact with them to time physiological dynamics in their target tissues around the day.

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“…Is circadian amplitude in gene expression affected by growth conditions? This topic of early circadian rhythmicity has been recently reviewed (Vallone et al, 2007). In mammals, the fetal clock is synchronized with the outside environment by maternal signals (Reppert and Schwartz, 1983;Reppert, 1995).…”

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confidence: 99%

Circadian Timekeeping during Early Arabidopsis Development

2008

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The circadian coordination of organismal biology with the local temporal environment has consequences for fitness that may become manifest early in development. We directly explored the development of the Arabidopsis (Arabidopsis thaliana) clock in germinating seedlings by monitoring expression of clock genes. Clock function is detected within 2 d of imbibition (hydration of the dried seed). Imbibition is sufficient to synchronize individuals in a population in the absence of entraining cycles of light-dark or temperature, although light-dark and temperature cycles accelerate the appearance of rhythmicity and improve synchrony among individuals. Oscillations seen during the first 2 d following imbibition are dependent on the clock genes LATE ELONGATED HYPOCOTYL, TIMING OF CAB EXPRESSION1, ZEITLUPE, GIGANTEA, PSEUDO-RESPONSE REGULATOR7 (PRR7), and PRR9, although later circadian oscillations develop in mutants defective in each of these genes. In contrast to circadian rhythmicity, which developed under all conditions, amplitude was the only circadian parameter that demonstrated a clear response to the light environment; clock amplitude is low in the dark and high in the light. A circadian clock entrainable by temperature cycles in germinating etiolated seedlings may synchronize the buried seedling with the local daily cycles before emergence from the soil and exposure to light.

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Start the clock! Circadian rhythms and development

Cited by 69 publications

References 145 publications

Circadian rhythms in the morphology of neurons in Drosophila

Circadian rhythms in the morphology of neurons in Drosophila

Glucocorticoids and the circadian clock

Circadian Timekeeping during Early Arabidopsis Development

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