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.  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.  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.  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.