Figure 5.—

Extragenic suppression of the uaY12 mutation and suppressor-dependent drug sensitivity. (A and B) Expression of the hxA, uaZ, uapA, and uaY genes in the 12r122 and 12r128 strains. Experimental conditions and symbols are as in Figure 3. The values of B correspond to the average values of three independent Northern blots. The maximal SD values found are 8% for hxA, 14% for uaZ, 14% for uapA, and 11% for uaY. (C) Growth tests in the presence of paromomycin and cycloheximide. The strain numbers and relevant genotypes are shown above each panel. The different strains were inoculated on supplemented minimal media containing 5 mm of ammonium tartrate (NH₄⁺) with or without the relevant inhibitor. The final concentration of paromomycin or cycloheximide in the plate is shown on the right. The plates were incubated for 2 days at 37°.