The activities of the two /3-galactosidases of Neurospora increased in response to the presence of lactose or galactose. D-Xylose preferentially induced higher levels of activity in one of these enzymes. The initial period of the inductive response was examined in cultures transferred from noninducing to inducing media. Variations in the ratio of activities of these enzymes during this induction period indicate that their induction was not coordinate. The induction of the ,8-galactosidases of

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... urospora was less sensitive to low concentrations of inducers than was the induction of the ,B-galactosidase of bacteria; the time lag of induction was greater in the eucaryotic organism, and the maximal induction of active enzyme was less than that observed in bacteria. on May 9, 2020 by guest