induced by exposure to ethanol, air, or both (Fig. 2B). Gene expression changes following ethanol exposure were generally of greater magnitude than following air exposure. However, some genes (e.g., Cp1 and Cyp4p2) showed greater air regulation, and others (CG32602 and CG13422) showed regulation by both ethanol and air. In general, ethanol-regulated genes showed either transient changes (clusters 1, 2, 8, and 9) or only later changes (clusters 3, 6, and 7). A search for over-represented GO terms associated with these clusters identified, among others, terms for odorant binding, metabolism, regulation of signal transduction, nucleic acid binding, Toll signaling, Ras signal transduction, and cytoskeletal organization and biogenesis (Table S2). Remarkably, similar categories were identified in 2 mammalian studies that modeled specific aspects of addiction: an analysis of gene expression differences between alcohol preferring and nonpreferring mice, and an analysis of the effects of chronic cocaine exposure on gene expression (Mulligan et al., 2006; Renthal et al., 2009). The quality of the microarray analysis was confirmed by qPCR, with 11 of 14 genes tested showing similar regulation of expression by ethanol exposure (Fig. 2C to F and data not shown).
