Isolation and characterization of a temperature-sensitive circadian clock mutant of Neurospora crassa.
A new circadian clock mutant has been isolated in Neurospora crassa. This new mutation, called period-6 (prd-6), has two features novel to known clock mutations. First, the mutation is temperature sensitive. At restrictive temperatures (above 21 degrees) the mutation shortens circadian period length from a wild-type value of 21.5 hr to 18 hr. At permissive temperatures (below 21 degrees) the mutant has a 20.5-hr period length close to that of the wild-type strain. Second, the prd-6 mutation is epistatic to the previously isolated clock mutation period-2 (prd-2). This epistasis is unusual in that the prd-2 prd-6 double mutant strain has an 18-hr period length at both the restrictive and permissive temperatures. That is, the temperature-sensitive aspect of the phenotype of the prd-6 strain is lost in the prd-2 prd-6 double mutant strain. This suggests that the gene products of the prd-2 and prd-6 loci may interact physically and that the presence of a normal prd-2+ protein is required for low temperature to "rescue" the prd-6 mutant phenotype. These results, combined with our recent finding that prd-2 and some alleles of the frq gene show genetic synergy, suggest that it may be possible to establish a more comprehensive model of the Neurospora circadian clock.
Morgan
L W
LW
Department of Biology, University of California, Santa Cruz 95064, USA.
Feldman
J F
JF
D001683:Biological Clocks / Q000235:genetics; D002874:Chromosome Mapping; D002940:Circadian Rhythm / Q000235:genetics*; D004843:Epistasis, Genetic; D005800:Genes, Fungal; D009154:Mutation; D009492:Neurospora crassa / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D010641:Phenotype; D013696:Temperature; D013997:Time Factors