Directional effect of hydrocortisone acetate on the free amino acids of Neurospora crassa

Neurospora crassa was used in an attempt to clarify the mode of action of hydrocortisone upon protein and amino acid metabolism. Simple synthetic media containing various single amino acids as nitrogen source were used. Irrespective of the nitrogen source, hydrocortisone acetate caused the concentration of individual free amino acids to approach a base-line value regardless of whether control values were above or below the base line. This was referred to as a “directional effect.”