Fig. 2

a Phylogenetic relationship of initiator caspases in bivalves (blue) compared to other vertebrate and invertebrate homologues (black). Values above/below nodes separated by slash show bootstrap support values for Maximum Likelihood (ML) analysis as percentage of bootstrap values for the main tree with additional Bayesian Inference (BI) posterior probabilities. /x indicates the nodes obtained from the BI which were different from the ML analysis. Human caspase-3 and caspase-7 homologues used as outgroup. Phylogenetic relationship of caspase-recruitment domain (CARD) b or single/double death-effector domains (DED) c. d Schematic representation of initiator caspase structure of bivalves with the CARD, DED or death domain (DD) motifs in their prodomains and the two caspase specific domains: large p20 and small p10 domain. The p20 active sites motif (..H … ..QACXG) with the conserved histidine and cysteine residue in bold is shown for each bivalve caspase homolog. e Schematic representation of gene location for each identified C. gigas caspase on the pseudo-chromosomes (LG). Mb: megabase. Aj: Apostichopus japonicus, Bf: Branchiostoma floridae, Bl: Branchiostoma lanceolatum, Ca: Crassostrea angulata, Ce: Caenorhabditis elegans, Cg: Crassostrea gigas, Ch: Crassostrea hongkongensis, Dl: Dicentrarchus labrax, Dm: Drosophila melanogaster, Dr.: Danio rerio, Hd: Haliotis diversicolor, Hdd: Haliotis discus discus, Hl: Holothuria leucospilota, Hs: Homo sapiens, Mc: Mytilus californianus, Mco: Mytilus coruscus, Mg: Mytilus galloprovincialis, Mm: Mus musculus, Mt: Molgula tectiformis, Tt: Tubifex tubifex, Xl: Xenopus laevis. _amf: amphibian, −amp: amphioxus, _ann: annelid, _asc: ascidian, _ech: echinoderm, _fish: fish, _mam: mammal, _mol: mollusc