Fig. 3

Toll pathway members in malacostracans. a Soluble PRRs such as the GNBP1 and GNBP3 are involved in the recognition of non-self, e.g. peptidoglycans and β-glucans, which triggers proteolytic through the activation of CLIP-domain serine proteases. The cytokine Spaetzle is cleaved by the Spaetzle processing enzyme and this activates the Toll receptor. Signalling through Toll acts via the Toll-induced signalling complex (TISC), comprising of three proteins containing death-domains: Tube, myeloid differentiation primary-response gene 88 (MyD88) and Pelle. TICS signal is transduced to Cactus (a homologue of the mammalian inhibitor of NF-κB). Cactus is phosphorylated, polyubiquitylated and degraded and the dorsal-related immunity factor (DIF) is translocated to the nucleus. DIF binds to NF-κB response elements to induce gene expression. The graphs represent the total number of b Spätzle, c MyD88, Tube and Pelle and d Dorsal and Cactus transcripts in malacostracans. The y-axes represent total number of genes identified in all 55 malacostracan species for each family. Each species is represented by a number on the X-axes and a complete list of species is available in Additional file 3: Table S2. Black horizontal bars below each graph delimit the five orders of malacostracans and the numbers in parentheses (x/y) represent the following: x = number of species in which a particular gene family is found and y = total number of species in each order. Phylogenetic trees of e Toll-interacting protein (TOLLIP), f Dorsal and g Cactus are constructed using the maximum-likelihood method from an amino acid multiple sequence alignment. Taxa labels are depicted as their respective colour codes. Bootstrap support values (n = 1000) for all trees can be found in Additional file 26: Figure S14. Scale bar represents substitution per site