Figure 1

Co-expression decreases with increasing distance (Inset: blow-up of 0-10 intervening genes). Co-expression is strongest for direct neighbours (distance = 0), drops quickly up to 2 intervening genes, and then slowly decreases until it reaches average values for non-neighbours (dashed line) at very large distances. Co-expression of direct neighbours is significantly higher than for random pairs regardless of gene orientations (Table 1), and co-expression is higher than for random pairs up to 100 intervening genes (P < 0.02 for each distance bin). Co-expression is measured as Pearson's correlation coefficient of gene expression vectors across experiments. Distance is measured as the number of intervening genes along the chromosome.