Gene neighborhoods. Monte Carlo simulations (see Materials and methods) were used to identify statistically significant clusters of testis- and soma-biased genes using a series of window sizes ranging from five to 200 consecutive genes. Examples are shown for six gene neighborhoods that were found zero times in 100,000 replicated randomization tests. GADFLY  annotation images of the chromosomal regions for each neighborhood are shown with the genes identified by element species showing expression-bias, indicated by red boxes. The normalized intensities are shown below each neighborhood indicating high expression (yellow), moderate (red), low (blue) and below background (black). (a) A testis-biased cluster at cytological position 2L:35D4-F435, (b) a testis-biased cluster at 2R:50B1-50C6, (c) a testis-biased cluster at 2R:56E1-F9, (d) a testis-biased cluster at 2R: 59C3-D6, (e) a soma-biased cluster at 2R:47E1-F5 and (f) a soma-biased cluster at 2R:55C6-C8.