Upon infection in Drosophila, a melanization pathway is activated that is involved in sequestering and eliminating invading bacteria (Brennan and Anderson, 2004). The melanization pathway consists of a cascade of serine proteases that are inactivated by serpins, including Spn27A, that irreversibly bind serine protease catalytic sites. Transcript levels for the gene-encoding Spn27A were induced nearly 5-fold 3.5-hour following ethanol exposure termination (Fig. 6A). Bacterial infection causes a similar temporal pattern of Spn27A induction, and this up-regulation is thought to help limit the melanization reaction in time and space (De Gregorio et al., 2002). To begin to test the role of immune genes in ethanol responses, we characterized the effects of disrupting Spn27A. The transposon e02539 is inserted into the coding region of the Spn27A locus and is predicted to result in truncation of the Spn27A protein (Fig. 6B). Animals homozygous for e02539 exhibited maternal-effect lethality and increased spontaneous melanization, detected as discrete dark spots through the cuticle. These phenotypes are consistent with e02539 causing a strong loss-of-function for Spn27A (De Gregorio et al., 2002; Ligoxygakis et al., 2002). Spn27Ae02539 homozygotes
