Distribution of significant genes between all the chromosomes.

χ2 tests were performed in the available mutants under the null hypothesis of random distribution: Random, equal proportion; Norm.1, proportion normalized by chromosome length; Norm.2, normalized by number of genes in each chromosome (see Materials and Methods): *, p<0.1; **, p<0.05; ***, p<0.01; ****, p<0.001. Percentages are the contribution of the chromosome for each ablated gene to the deviation from each random distribution and were calculated as proportion of the χ2 values. If a chromosome other than that encoding the knock-out gene had more contribution is stated in “Other chrom”. Total genes are the number of the retrieved significant genes.