Abstract
The large (l) and small (s) isoforms of FREQUENCY (FRQ) are elements of interconnected feedback loops of the Neurospora circadian clock. The expression ratio of l-FRQ vs. s-FRQ is regulated by thermosensitive splicing of an intron containing the initiation codon for l-FRQ. We show that this splicing is dependent on light and temperature and displays a circadian rhythm. Strains expressing only l-FRQ or s-FRQ support short and long temperature-compensated circadian rhythms, respectively. The thermosensitive expression ratio of FRQ isoforms influences period length in wt. Our data indicate that differential expression of FRQ isoforms is not required for temperature compensation but rather provides a means to fine-tune period length in response to ambient temperature.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Alternative Splicing / genetics
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Alternative Splicing / radiation effects
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Amino Acid Sequence
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Base Sequence
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CLOCK Proteins
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Circadian Rhythm / physiology*
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Circadian Rhythm / radiation effects
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Fungal Proteins / chemistry
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Light
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Molecular Sequence Data
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Mutation / genetics
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Neurospora / cytology
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Neurospora / physiology*
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Neurospora / radiation effects
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Protein Isoforms / chemistry
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Protein Isoforms / genetics
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Protein Isoforms / metabolism
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Temperature*
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Time Factors
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Trans-Activators / chemistry
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Trans-Activators / genetics
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Trans-Activators / metabolism*
Substances
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FRQ protein, Neurospora crassa
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Fungal Proteins
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Protein Isoforms
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Trans-Activators
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CLOCK Proteins