Intergenic DNA increases with regulatory complexity in D. melanogaster and C. elegans. Expression indices were divided into bins, each containing approximately 10% of the entries in an index. Mean amount of intergenic DNA for each bin (± standard error) was plotted for all three expression indices (left): (a) FBx; (b) BDGPx; (c) WBx. The average amount of intergenic DNA flanking the genes in bins of greater regulatory complexity is significantly greater than that of bins of lower regulatory complexity in all three indices (Tukey-Kramer HSD, α = 0.05). In the nonparametric bivariate density plots of intergenic DNA versus index value (right), each contour represents a boundary including 10% of the data. The innermost red contour includes 10% of the data points and excludes the other 90%. The outermost purple contour includes 90% of the data points, whereas 10% fall outside this boundary.
Nelson et al. Genome Biology 2004 5:R25