Figure 4: Effects of Val-tRF or elevated pH on protein synthesis and cell growth. (a) Val-tRF inhibits H. volcanii in vitro translation. The relative amount of radiolabeled proteins in the absence (-) or in the presence of 3.3 μM Val-tRF is shown. The scrambled version of the Val-tRF (scr) served as specificity control. In all cases, the background values measured in reactions without S30 extracts were subtracted from all experimental points. Error bars represent the mean and standard deviation of at least three independent experiments. (b) Cell growth of unstressed H. volcanii cultures and of cells grown under alkaline conditions (pH 8.5) is shown. Cell density was measured at 600 nm and the average values of two independent growth curves each and their standard deviations are given.