Circadian rhythms in Neurospora crassa: oligomycin-resistant mutations affect periodicity.

Nuclear mutations conferring resistance to oligomycin, a mitochondrial inhibitor, shorten the period of the circadian conidiation rhythm of Neurospora crassa from the normal 21.5 hours to 18 to 19 hours and slow the linear growth rate by 30 percent. These olir mutations map very close to frq, a locus at which mutations affecting periodicity have been previously obtained. The possibilities are discussed that mitochondria are involved in circadian rhythm generation and that certain period-length mutations affect mitochondrial functions.