Transcriptional Profiling of Midgut Immunity Figure 7. Transcription of immunity-related proteins in the midgut positively respond to 20-E injection. All genes as indicated were significantly up-regulated at different time points after 20-E injection. *p,0.05; **p,0.001. doi:10.1371/journal.pone.0043769.g007 morphology. Surprisingly, the silkworm moth midgut is in a very weak condition (Fig. 1E and 1F). However, many Lepidoptera adults still use their midguts for nectar ingestion and digestion during the adult life stage [8,17], and the midgut of the butterfly has many layers of cells (Fig. 1C). In addition, some Lepidoptera insects produce antimicrobial proteins in their midgut during the wandering stage by an unknown mechanism [19,47]. We PLOS ONE | www.plosone.org 9 August 2012 | Volume 7 | Issue 8 | e43769