Fig. 1

Anatomy of Macrostomum lignano and sampling design for RNA-Seq. The main organ systems reside in four regions along the anterior-posterior body axis (i.e. the head, testis, ovary and tail regions). By cutting the worms in between two body regions (red dotted lines), four samples for RNA-Seq were collected (two-headed arrows): Sample A (head region; n = 400 worms); Sample B (head and testis regions; n = 300 worms); Sample C (head, testis and ovary regions; n = 200 worms); Sample D (entire worm, i.e. head, testis, ovary and tail regions; n = 100 worms). Differences in expression between adjacent samples were scored in order to classify the transcripts (in silico subtraction; see Table 1). Adult worms are about 1.5 mm in length. Interference contrast micrograph modified from Schärer et al. (2007) [97]