Search results
Results from the WOW.Com Content Network
Circadian rhythms have been documented for centuries. For example, French astronomer Jean-Jacques d’Ortous de Mairan noted the periodic 24-hour movement of Mimosa plant leaves as early as 1729. However, science has only recently begun to uncover the cellular mechanisms responsible for driving observed circadian rhythms.
A circadian rhythm (/ s ər ˈ k eɪ d i ə n /), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours.Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrained by the environment).
[1] [2] Oscillating genes are usually circadian and can be identified by periodic changes in the state of an organism. Circadian rhythms, controlled by oscillating genes, have a period of approximately 24 hours. For example, plant leaves opening and closing at different times of the day or the sleep-wake schedule of animals can all include ...
The best studied rhythm in chronobiology is the circadian rhythm, a roughly 24-hour cycle shown by physiological processes in all these organisms. The term circadian comes from the Latin circa, meaning "around" and dies, "day", meaning "approximately a day." It is regulated by circadian clocks.
Timeless (tim) is a gene in multiple species but is most notable for its role in Drosophila for encoding TIM, an essential protein that regulates circadian rhythm. Timeless mRNA and protein oscillate rhythmically with time as part of a transcription-translation negative feedback loop involving the period (per) gene and its protein.
In vertebrates, the master circadian clock is contained within the suprachiasmatic nucleus (SCN), a bilateral nerve cluster of about 20,000 neurons. [10] [11] The SCN itself is located in the hypothalamus, a small region of the brain situated directly above the optic chiasm, where it receives input from specialized photosensitive ganglion cells in the retina via the retinohypothalamic tract.
Pseudo-response regulator (PRR) refers to a group of genes that regulate the circadian oscillator in plants. There are four primary PRR proteins (PRR9, PRR7, PRR5 and TOC1/PRR1) that perform the majority of interactions with other proteins within the circadian oscillator, and another (PRR3) that has limited function.
The SCN is then able to influence the sleep wake cycle, acting as the "apex of a hierarchy" that governs physiological timing functions. [2] "Rest and sleep are the best example of self-organized operations within neuronal circuits". [1] A-riot-of-rhythms-neuronal-and-glial-circadian-oscillators-in-the-mediobasal-hypothalamus-1756-6606-2-28-S3