Fig. 5

Phylogenetic relationship of P. ornatus nuclear receptors based on ligand-binding domains. Phylogenetic analysis was conducted with the maximum likelihood method based on the JTT matrix-based model, supported by bootstrap analysis with 500 replicates. Associated bootstrap values are shown beside each node. The scale bar shows substitutions per site and the chequered background highlights the novel NR genes identified in this study. P. ornatus branches are highlighted in bold. The six canonical NR families are represented by P. ornatus transcripts identified in this study, with the NR1 group being supported by the inclusion of a Salmo salar thyroxine receptor. Vitamin D receptor-like (VDR-like) sequences from the barnacle Lepas anatifera and the horseshoe crab Limulus polyphemus were used to root the phylogram. HR97-like sequences are presented for representatives across the Crustacea to demonstrate the relationship of the new NRs across their taxonomic range. Three novel HR97-like genes have been provisionally named the molt-associated receptors MAR1, MAR2 and MAR3 (with the family designations NR1S, NR1Q and NR1R, respectively)