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Related Concept Videos

Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...
Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...
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The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
Prokaryotic Transcriptional Activators and Repressors01:58

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The organization of prokaryotic genes in their genome is notably different from that of eukaryotes. Prokaryotic genes are organized, such that the genes for proteins involved in the same biochemical process or function are located together in groups. This group of genes, along with their regulatory elements, are collectively known as an operon. The functional genes in an operon are transcribed together to give a single strand of mRNA known as polycistronic mRNA.
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Prokaryotic Transcriptional Activators and Repressors01:58

Prokaryotic Transcriptional Activators and Repressors

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Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response01:15

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Circadian rhythms are cyclic changes that are crucial in plasma drug concentrations. Various standard circadian parameters, including core body temperature, heart rate, and other cardiovascular factors, directly impact disease states and the therapeutic response to drug therapy.
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...

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Rapid Analysis of Circadian Phenotypes in Arabidopsis Protoplasts Transfected with a Luminescent Clock Reporter
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Delay in feedback repression by cryptochrome 1 is required for circadian clock function.

Maki Ukai-Tadenuma1, Rikuhiro G Yamada, Haiyan Xu

  • 1Laboratory for Systems Biology, RIKEN Center for Developmental Biology, Chuo-ku, Kobe, Hyogo, Japan.

Cell
|January 18, 2011
PubMed
Summary
This summary is machine-generated.

Delaying the expression of Cryptochrome 1 (Cry1) is crucial for the mammalian circadian clock to function correctly. This research demonstrates how specific DNA elements control Cry1

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In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters
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Last Updated: Jun 5, 2026

Rapid Analysis of Circadian Phenotypes in Arabidopsis Protoplasts Transfected with a Luminescent Clock Reporter
07:42

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In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters
07:44

In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters

Published on: July 4, 2018

Area of Science:

  • Chronobiology
  • Molecular Biology
  • Genetics

Background:

  • The mammalian circadian clock regulates daily biological rhythms.
  • Feedback repression is essential for clock function, but direct evidence has been lacking.
  • Cryptochrome 1 (Cry1) is a key protein involved in circadian rhythm regulation.

Purpose of the Study:

  • To investigate the requirement of delayed feedback repression in the mammalian circadian clock.
  • To elucidate the regulatory mechanisms underlying the evening-time expression of Cryptochrome 1 (Cry1).
  • To determine the role of Cry1 expression timing in maintaining circadian rhythmicity.

Main Methods:

  • Analysis of Cry1 gene regulatory elements, including D boxes and RREs.
  • Construction and testing of a synthetic composite promoter for Cry1.
  • Development and application of a phase-vector model.
  • Genetic complementation assays in Cry1(-/-):Cry2(-/-) cells.

Main Results:

  • A combination of day-time (D box) and night-time (RREs) elements drives evening-time Cry1 expression.
  • A synthetic promoter recapitulated this expression pattern.
  • Modulation of phase delay was observed by coordinating these elements.
  • Substantial delay in Cry1 expression was necessary to restore circadian rhythmicity in knockout cells.
  • Prolonged Cry1 delay led to slowed circadian oscillations.

Conclusions:

  • Phase delay in Cryptochrome 1 (Cry1) transcription is a critical requirement for mammalian clock function.
  • The interplay between promoter and enhancer elements dictates Cry1 expression timing.
  • The precise timing of Cry1 expression influences the speed of circadian oscillations.