Circadian clocks are present in most eukaryotes and some prokaryotes and control rhythms in behavior, physiology and gene expression. One well-characterized circadian clock is that of Neurospora crassa. In addition to the well-described N. crassa FRQ/WCC oscillator, several lines of evidence have implied the presence of other oscillators which may have important functions in the N. crassa circadian clock system. However, the molecular details are only known for the core FRQ/WCC oscillator. The light mutant oscillator (LMO) was identified by two mutations (LM-1 and LM-2) and shown to control developmental rhythms in constant light (LL), conditions in which the FRQ/WCC oscillator is not functional. The objective of this project was to determine whether the developmental rhythms driven by the LMO are circadian, whether the components of the LMO communicate with components of the FRQ/WCC oscillator, and to begin to define the molecular nature of the LMO. First, the conditions for growth of the LM-1 mutant strain that reveals the best circadian rhythm of development in LL were found. Second, the LMO was determined to display the three properties required of a circadian oscillator. Third, the LMO was shown to function independently of the FRQ/WCC oscillator to control developmental rhythms in LL. However, evidence suggests that the FRQ/WCC oscillator and the LMO communicate with each other. Finally, using Cleaved Amplified Polymorphic Sequence (CAPS) markers, the LM-1 mutation was genetically mapped to the right arm of linkage group I within a 1069 kb region. Together, these results provide a start towards understanding of the complexity of oscillators that form a circadian clock in organisms.
