genetic selection for circadian output pathway mutations in Neurospora crassa

In most organisms, circadian oscillators regulate the daily rhythmic expression of clock-controlled genes (ccgs). However, little is known about the pathways between the circadian oscillator(s) and the ccgs. In Neurospora crassa, the frq, wc-1, and wc-2 genes encode components of the frq-oscillator....

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Published in:Genetics (Austin) 2004-05, Vol.167 (1), p.119-129
Main Authors: Vitalini, M.W, Morgan, L.W, March, I.J, Bell-Pedersen, D
Format: Article
Language:English
Subjects:
Blotting, Northern
Circadian Rhythm
Densitometry
Fungal Proteins - genetics
Fungi
Gene expression
Gene Expression Regulation
Genes
Genetic Techniques
Genetics
Genotype
Models, Biological
Mutagenesis, Site-Directed
Mutation
Neurospora crassa
Neurospora crassa - genetics
Nucleic Acids - chemistry
Oscillometry
Phenotype
Plasmids - metabolism
Promoter Regions, Genetic
RNA - metabolism
RNA, Messenger - metabolism
Time Factors
Ultraviolet Rays
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Summary:In most organisms, circadian oscillators regulate the daily rhythmic expression of clock-controlled genes (ccgs). However, little is known about the pathways between the circadian oscillator(s) and the ccgs. In Neurospora crassa, the frq, wc-1, and wc-2 genes encode components of the frq-oscillator. A functional frq-oscillator is required for rhythmic expression of the morning-specific ccg-1 and ccg-2 genes. In frq-null or wc-1 mutant strains, ccg-1 mRNA levels fluctuate near peak levels over the course of the day, whereas ccg-2 mRNA remains at trough levels. The simplest model that fits the above observations is that the frq-oscillator regulates a repressor of ccg-1 and an activator of ccg-2. We utilized a genetic selection for mutations that affect the regulation of ccg-1 and ccg-2 by the frq-oscillator. We find that there is at least one mutant strain, COP1-1 (circadian output pathway derived from ccg-1), that has altered expression of ccg-1 mRNA, but normal ccg-2 expression levels. However, the clock does not appear to simply regulate a repressor of ccg-1 and an activator of ccg-2 in two independent pathways, since in our selection we identified three mutant strains, COP1-2, COP1-3, and COP1-4, in which a single mutation in each strain affects the expression levels and rhythmicity of both ccg-1 and ccg-2.
ISSN:0016-6731
1943-2631
1943-2631
DOI:10.1534/genetics.167.1.119