Figure 3.—

Expression of the hxA, uaZ, uapA, and uaY genes in the uaY12 revertants 12r113, 12r118, 12r3, and 12r18. (A) Northern blot analysis of hxA, uaZ, uapA, and uaY gene expression. The relevant uaY allele of each strain is shown at the top. See materials and methods for growth conditions and probe description. Mycelia were grown on urea as a nitrogen source for a total of 10 hr at 37°, after 9 hr growth uric acid (UA, induced) or urea (Ur, noninduced) was added at the concentrations indicated in materials and methods. (B) Quantification of the hxA, uaZ, uapA, and uaY transcripts. The Phosphoimager readings were corrected using the corresponding acnA transcript signal intensity as a measure of RNA loading. All values are expressed in relation to the wild-type mycelia induced by uric acid and correspond to the average values of three independent Northern blots. The maximal SD values found are 15% for hxA, 17% for uaZ, 14% for uapA, and 17% for uaY. The reference values (corresponding to the arbitrary value of 100) are shown in boldface type.