Quantitative Fitness Analysis Identifies <i>exo1∆</i> and Other Suppressors or Enhancers of Telomere Defects in <i>Schizosaccharomyces pombe</i>

<div><p>Synthetic genetic array (SGA) has been successfully used to identify genetic interactions in <i>S</i>. <i>cerevisiae</i> and <i>S</i>. <i>pombe</i>. In <i>S</i>. <i>pombe</i>, SGA methods use either cycloheximide (<i>C</i>) or heat shock (<i>HS</i>) to select double mutants before measuring colony size as a surrogate for fitness. Quantitative Fitness Analysis (QFA) is a different method for determining fitness of microbial strains. In QFA, liquid cultures are spotted onto solid agar and growth curves determined for each spot by photography and model fitting. Here, we compared the two <i>S</i>. <i>pombe</i> SGA methods and found that the <i>HS</i> method was more reproducible for us. We also developed a QFA procedure for <i>S</i>. <i>pombe</i>. We used QFA to identify genetic interactions affecting two temperature sensitive, telomere associated query mutations (<i>taz1Δ</i> and <i>pot1-1</i>). We identify <i>exo1∆</i> and other gene deletions as suppressors or enhancers of <i>S</i>. <i>pombe</i> telomere defects. Our study identifies known and novel gene deletions affecting the fitness of strains with telomere defects. The interactions we identify may be relevant in human cells.</p>