The Rhythms of Three Clock Mutants of Ascobolus Immersus

SUMMARYAscobolus immersus clock mutants have a periodic growth pattern clue to branching and sub-branching at the leading edge. The linear growth rate is constant, only the branching pattern is rhythmic. The time period necessary for the formation of each band is temperature dependent, light independent and chemically controllable. Two of the mutants grow non-rhythmically on a chemically defined minimal medium with 1% sucrose. Substitution of other sugars or glycerol as carbon sources does not induce rings. Clear, consistent growth bands are formed with the addition of cysteine, serine, isoleucine, ornithine or particularly arginine. This dependence on amino acids for rhythmic growth is concentration dependent.