Observations on the Behavior of Suppressors in Neurospora

A suppressor of pyrimidineless 3a (37301) and some aspects of the behavior of the suppressed mutant have been described earlier. [1] The observation that lysine, ornithine, citrulline and arginine influence growth responses of the suppressed mutant suggested studies of the behavior of recombinants involving pyr 3a and s and mutants having requirements for these amino acids. Effects of the pyrimidineless mutant and its suppressor upon certain lysine-requiring mutants have been reported. [2] The present paper deals with a somewhat greater variety of interactions observed between pyr 3a and s and mutants which utilize proline, ornithine, citrulline or arginine. [3] These interactions include suppression of two non-allelic prolineless mutants by the pyrimidineless suppressor and partial suppression of pyr 3a by three non-allelic ornithineless mutants