Figure 3

Light regulation of the An. gambiae transcriptome. (A) Model of the regulation of 24 hr rhythmic expression by the endogenous circadian clock and the LD cycle from our studies and other organisms [30, 37, 48, 50, 51, 69–72]. CCGs are a subset of rhythmic genes with expression driven directly by the circadian clock. Light synchronizes or resets the clock, but activity and rhythms in CCGs persist without LD cycle input. Under LD conditions, additional “LD-driven rhythmic genes” are expressed rhythmically, and a proportion of CCGs have inhibited or enhanced rhythmicity, controlled by both the clock and the direct action of light. (B) Microarray data of OBPs highlights the diversity of mosquito light-regulated expression, with various levels of interaction between clock-and light-driven control. Type I group (e.g. OBP6) are rhythmic under LD and DD conditions, with amplitude of expression higher under LD conditions. Type II group, (e.g. OBP4) have rhythmic expression dampened in DD, but this occurs in the second cycle under constant conditions. Expression in the first cycle does not dampen during subjective day relative to subjective night, as would be expected from LD cycle expression. Type III group (e.g. OBP54) has rhythmic expression under LD conditions but virtually no expression under DD. As LD cycle collection began at ZT12, and DD collection at subjective CT0, ZT16 and 20 data are appended to end of the collection. Day/subjective day and night/subjective night indicated by the horizontal hashed/black bars. Hypothesized regulation via light box (LB) and/or clock box (CB) response elements. (C) Hierarchical clustering of additional genes clustering with and displaying a similar LD to DD cycle phenomenon as OBP4 (type II). Expression values normalized to mean value across the time course of each gene, red indicates higher, green lower expression. Subjective day and night indicated by the horizontal gray/black bars. Data shown from head samples.