<p>(A) Lowering SPT5 reduces male viability compared to sisters. All males were <i>roX1 roX2</i> double mutants and partially rescued by one copy of the <i>[GMroX1-75C]</i> transgene. Males wild type for all other loci are rescued 29%, but flies missing one copy of the indicated dosage compensation genes have reduced male viability. ** p<0.01 * p<0.05 Fisher exact test. Detailed results in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003073#pgen.1003073.s008" target="_blank">Table S2</a>. (B) Reducing <i>Spt5</i> rescues the sterility of <i>[H83M2]</i> females. <i>y w; Spt5<sup>880C</sup>/CyO y+</i> females were mated to <i>w/Y; [w<sup>+</sup> H83M2]/+</i> males. Only the adults eclosing during the first two days are indicated to measure delayed development. <i>[w<sup>+</sup> H83M2]</i> escaper females produced few eggs and were sterile (black bar). [<i>w<sup>+</sup> H83M2</i>] females heterozygous for <i>Spt5</i> regained fertility (gray bars). N = number of brothers recovered for each class. p calculated by Fisher exact test. (C) Males homozygous for the <i>[GMroX1]</i> transgene at 75C have a few pigmented sectors. (D) Singly, <i>Spt5</i> slightly reduces and (E) <i>msl1<sup>P864L</sup></i> dramatically increases local MSL activity. (F) When present together, <i>Spt5<sup>S14F</sup></i> blocks the increased activity of the <i>msl1<sup>P864L</sup></i> gain of function allele. See <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003073#pgen.1003073.s002" target="_blank">Figure S2</a> and <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003073#pgen.1003073.s003" target="_blank">Figure S3</a> for additional genetic analysis.</p
