Measuring effects for poorly characterized genes. (a) Counting slow-growth effects for under-characterized genes. Histograms show the total number of mutants with at least x significant slow-growth effects in our data from the set of uncharacterized genes (left, orange), and genes with little to no fitness defect on synthetic complete media (right, blue; single mutant fitness > 98% of wild-type). As a control, the expected number of false positives (20% of significant effects in each condition) were randomly distributed among all genes, and the number of effects for each gene was counted again. Gray bars show the mean of 1,000 such randomizations. (b) Z-score data show specific growth defects for the uncharacterized gene FMP32 when grown on proline or arginine. (c) Liquid growth confirmations for effects highlighted in X-axis, time in hours. Y-axis, optical density. (b). Two replicates of FMP32 mutants are shown (blue line) along with six replicates of a wild-type strain (black dashed line) in two proline and two arginine conditions. The effects are pronounced when compared to observations in similar ammonium conditions.