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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,...
Biological Clocks and Seasonal Responses02:45

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.

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Related Experiment Video

Updated: Jul 5, 2026

Single-cell Resolution Fluorescence Live Imaging of Drosophila Circadian Clocks in Larval Brain Culture
07:05

Single-cell Resolution Fluorescence Live Imaging of Drosophila Circadian Clocks in Larval Brain Culture

Published on: January 19, 2018

A PER/TIM/DBT interval timer for Drosophila's circadian clock.

L Saez1, P Meyer, M W Young

  • 1Laboratory of Genetics, The Rockefeller University, New York, New York 10021, USA.

Cold Spring Harbor Symposia on Quantitative Biology
|April 19, 2008
PubMed
Summary
This summary is machine-generated.

Drosophila circadian rhythms rely on PERIOD (PER) and Timeless (TIM) proteins. Live cell imaging revealed a cytoplasmic interval timer regulating PER/TIM nuclear translocation, crucial for daily rhythmicity.

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Circadian Entrainment of Drosophila Melanogaster
07:12

Circadian Entrainment of Drosophila Melanogaster

Published on: June 3, 2020

Related Experiment Videos

Last Updated: Jul 5, 2026

Single-cell Resolution Fluorescence Live Imaging of Drosophila Circadian Clocks in Larval Brain Culture
07:05

Single-cell Resolution Fluorescence Live Imaging of Drosophila Circadian Clocks in Larval Brain Culture

Published on: January 19, 2018

Circadian Entrainment of Drosophila Melanogaster
07:12

Circadian Entrainment of Drosophila Melanogaster

Published on: June 3, 2020

Area of Science:

  • Chronobiology
  • Molecular biology
  • Cell biology

Background:

  • Circadian rhythms in Drosophila are regulated by a transcriptional negative feedback loop involving PERIOD (PER) and Timeless (TIM) proteins.
  • The translocation of PER and TIM from the cytoplasm to the nucleus is a key step in this feedback loop and influences the period length of the rhythm.
  • An interval of cytoplasmic retention of PER and TIM proteins is thought to be critical for determining circadian period length.

Purpose of the Study:

  • To investigate the physical interactions and nuclear translocation dynamics of PER, TIM, and Doubletime (DBT) proteins in cultured Drosophila cells.
  • To elucidate the role of a cytoplasmic interval timer in regulating the nuclear entry of circadian clock proteins.
  • To establish a live cell imaging system for studying the molecular mechanisms underlying circadian behavior in Drosophila.

Main Methods:

  • Utilized live cell video microscopy to observe individual cultured Drosophila cells.
  • Employed green fluorescent protein (GFP) tags to visualize the dynamic patterns of stability and localization of DBT, PER, and TIM proteins.
  • Analyzed the physical interactions and nuclear translocation of these key circadian clock components.

Main Results:

  • Observed dynamic patterns of stability and localization for DBT, PER, and TIM proteins in cultured cells that mirrored in vivo findings.
  • Provided evidence for the existence of a cytoplasmic interval timer that governs the nuclear translocation of PER and TIM proteins.
  • Demonstrated the utility of the cultured cell assay for studying circadian clock gene interactions.

Conclusions:

  • The findings suggest that a cytoplasmic interval timer plays a critical role in regulating the nuclear entry of circadian clock proteins in Drosophila.
  • The established live cell assay is a powerful tool for dissecting the molecular mechanisms and genetic interactions involved in generating circadian behavior.
  • This research contributes to a deeper understanding of the temporal regulation of gene expression in circadian systems.