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Updated: Jan 1, 2026
Circadian Entrainment of Drosophila Melanogaster
Published on: June 3, 2020
A Comparison of the Neurospora and Drosophila Clocks
1Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, and Center for Circadian Biology, UCSD, La Jolla, California.
Abstract:
In Neurospora and other fungi, the protein frequency (FRQ) is an integral part and a negative element in the fungal circadian oscillator. In Drosophila and many other higher organisms, the protein period (PER) is an integral part and a negative element of their circadian oscillator. Employing bioinformatic techniques, such as BLAST, CLUSTAL, and MEME (Multiple Em for Motif Elicitation), 11 regions (sequences) of potential similarity were found between the fungal FRQ and the Drosophila PER. Many of these FRQ regions are conserved in many fungal FRQ(s). Many of these PER regions are conserved in many insects. In addition, these regions are also of biological significance since mutations in these regions lead to changes in the circadian clock of Neurospora and Drosophila. Many of these regions of similarity between FRQ and PER are also conserved between the Drosophila PER and the mouse PER (mPER2). This suggests conserved and important regions for all 3 proteins and a common ancestor, possibly in those amoeba, such as Capsaspora, that sits at the base of the phylogenetic tree where fungi and animals diverged. Two additional examples of a possible common ancestor between Neurospora and Drosophila were found. One, the white collar (WC-1) protein of Neurospora and the Drosophila PER, shows significant similarity in its Per/Arnt/Sim (PAS) motifs to the PAS motif of an ARNT-like protein found in the amoeba, Capsaspora. Two, both of the positive elements in each system (i.e., WC-1 in Neurospora and cycle [CYC] in Drosophila), show significant similarity to this Capsaspora ARNT protein. A discussion of these findings centers on the long-time debate about the origins of the many different clock systems (i.e., independent evolution or common ancestor as well as to the question of how new genes are formed).
Insights
Bioinformatic analysis reveals conserved sequence similarities between fungal FRQ and insect/mammalian PER proteins, suggesting a common evolutionary origin for circadian clocks. These findings support the hypothesis of a shared ancestor predating the divergence of fungi and animals.
Area of Science:
- Evolutionary Biology
- Chronobiology
- Molecular Biology
Background:
- Circadian rhythms are regulated by molecular oscillators in diverse organisms.
- Key components include negative regulators like Frequency (FRQ) in fungi and Period (PER) in higher organisms.
Purpose of the Study:
- To investigate evolutionary links between fungal and animal circadian clock proteins.
- To identify conserved regions and potential common ancestry.
Main Methods:
- Bioinformatic analyses including BLAST, CLUSTAL, and MEME.
- Comparative sequence analysis of FRQ, PER, and related proteins.
Main Results:
- Identified 11 conserved regions between fungal FRQ and *Drosophila* PER.
- These regions are functionally significant, as mutations affect circadian clock function.
- Similarities were also found between *Drosophila* PER and mouse PER2 (mPER2), and between components of fungal and fly circadian systems (WC-1, CYC) and an amoeba ARNT protein.
Conclusions:
- Suggests a common ancestor for fungal and animal circadian systems, possibly predating the fungi-animal divergence.
- Highlights conserved protein domains crucial for circadian clock function across species.
- Provides evidence for evolutionary conservation of core clock mechanisms.
