Arginase Induction in Aspergillus nidulans

The induction of arginase in the fungus Aspergillus nidulans depends on the synthesis of messenger and its subsequent translation, as is shown by selective inhibition of the two processes by proflavine and actidione. In mycelium grown at 30°C messenger synthesis starts with no measurable delay but the enzyme appears 6 min after arginine addition. The stability of the enzyme is accompanied by the lability of its messenger, the coding capacity of which decays with the half‐life of 2.7 min. The synthesis of messenger can be separated from its translation by including actidione (5 μg/ml) in an arginine‐supplemented culture. After the withdrawal of inducer and inhibitor the expression of arginase messenger takes place. The 4.5‐fold increased stability of messenger observed under conditions of blocked translation may be responsible for its accumulation in presence of actidione.