FIG. 2.

AmtA is required for intracellular ammonia homeostasis. (A) Intracellular ammonia/ammonium levels. Cells were collected at 0, 12, and 20 h of development and homogenized, and the amounts of ammonia/ammonium were determined by an ammonia electrode. Values indicate means ± standard errors of the means (SEM) (n = 3). (B) Extracellular ammonia levels. Media were collected at the indicated time points, and the amounts of ammonia were determined as described in Materials and Methods. Values indicate means ± SEM (n = 3).