Fig. 4

Structure and early temporal expression of frizzled-related genes in Platynereis. a Structural domains of the Platynereis frizzled receptors, sFRPs, and FzCRD-1. N-terminal gray boxes denote membrane localizing signal peptides. Yellow boxes are CRDs and green boxes are NTR domains. Black and red box is the seven-pass frizzled transmembrane domain. Small green box on FzCRD-1 indicates possible N-terminal remnant of a NTR domain. Black lines indicate poorly conserved regions. b–f Temporal expression of frizzled-related genes during early Platynereis development. b fz1/2/7, (C) fz9/10, d fz5/8, e sfrp1/2/5, and f fzCRD-1. The plots illustrate the relative expression levels in FPKM (fragment per kilobase per million mapped reads) based on RNA-seq (Additional file 4: Methods and Results). X axis: developmental time in hours post fertilization (hpf). Y axis: FPKM. Two biological replicates are shown for each graph with the replicate with the higher FPKM value at each time point (Rep. 1) denoted by blue lines and the replicate with lower values at each time point (Rep. 2) denoted by red lines