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Circadian Rhythms and Gene Regulation

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...

Circadian Rhythms and Gene Regulation

Circadian Rhythms and Gene Regulation

Biological Clocks and Seasonal Responses

Biological Clocks and Seasonal Responses

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.

Correlation between ECG and Cardiac Cycle

Correlation between ECG and Cardiac Cycle

The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...

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Updated: May 1, 2026

Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters

Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters

Published on: September 27, 2012

Machine learning helps identify CHRONO as a circadian clock component.

Ron C Anafi¹, Yool Lee², Trey K Sato²

¹Division of Sleep Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America; Center for Sleep and Circadian Neurobiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America.

|April 17, 2014

Summary

This summary is machine-generated.

Researchers discovered CHRONO, a new clock gene regulating daily rhythms. This computational and experimental study identifies CHRONO as a key player in circadian molecular dynamics, impacting physiology and behavior.

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Last Updated: May 1, 2026

Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters

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Published on: September 27, 2012

Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures

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Published on: November 11, 2016

Analysis of Circadian Photoresponses in Drosophila Using Locomotor Activity

Analysis of Circadian Photoresponses in Drosophila Using Locomotor Activity

Area of Science:

Chronobiology
Molecular Biology
Genetics

Background:

Daily rhythms in physiology and behavior are driven by

Purpose of the Study:

To accelerate the discovery of novel clock genes
To identify and prioritize candidate clock components using a computational approach
To experimentally validate the function of candidate genes in circadian regulation

Main Methods:

Probabilistic machine learning to integrate genome-scale data
Mammalian two-hybrid screens to identify interactions
In vitro cellular rhythm modulation assays
Bi-molecular fluorescence complementation and co-immunoprecipitation
CHRONO knockout mouse model

Main Results:

A computational approach identified candidate clock genes
Several candidates physically interact with known clock components
CHRONO (Gene Model 129) represses the BMAL1/CLOCK transcriptional complex by abrogating BMAL1 binding to CBP
CHRONO knockout mice exhibit a prolonged free-running circadian period

Conclusions:

CHRONO is a functional clock component
CHRONO provides a new layer of control on circadian molecular dynamics
The discovery has implications for understanding metabolic, psychiatric, and neoplastic disorders