Figure 4.

Basal gene expression is modulated by period and light. “Heat-plot” rank profiles of expression levels of genes exhibiting significant change in basal expression differences between experimental conditions (P < 0.0001, Mann–Whitney U test) are shown. From left to right, entire cycles (6 or 8 time points, in LD or DD) are grouped. (A) Expression levels of 650 genes from DD conditions on each of a total of 32 microarrays (y w, 20; per⁰¹, 12). (Upper) Those 330 genes with expression levels significantly higher in control flies (y w-Hi). (Lower) Those 320 genes with expression levels significantly higher in per⁰¹(per-Hi). Pseudocolor indicates relative rank order in expression (yellow, highest; blue, lowest). (B) Comparison of control flies kept in LD versus DD. Those 178 genes that exhibit significant differences in expression between LD (17 measurements) and DD (20 measurements) are shown. LD-Hi, higher average expression in LD; DD-Hi, higher average expression in DD. (C) Comparison of per⁰¹ flies between LD versus DD (12 measurements each). Other markings are as described for B. (B and C) Data for the same 178 genes, displayed in register. (D) Representative expression levels of individual genes from B and C, as denoted by numbers in parenthesis. Microarray intensity values of control LD (17 points), control DD (20 points), per⁰¹flies in LD (12 points), and per⁰¹ flies in DD (12 points) conditions are shown as means (+SE).