3.2 | Development-related genes for key enzymes, ion channels, receptors and secretome
To understand the genetic basis for the adaptation ofB. schroederi to the parasitic life, we assessed the abundance of several major protein classes in B. schroederi , A. suum , P. univalens , and T. canis (Table S10 and Fig. S12b). A genome-wide search enabled us to identify 62 G-protein coupled receptors (GPCRs), 437 proteases and protease inhibitors (Supplementary Data 2c). Some chemoreceptor families, especially those differentially expressed during the life cycle, were almost completely conserved among nematodes. For example, the homologues of Caenorhabditis elegans daf-37(GeneID: Baysch11898) and daf-38 (GeneID: Baysch06944), which are known to mediate ascaroside signaling, are expressed during the transition from dauer larvae to infective larvae (Park et al., 2012). By comparing with the ligand-gated ion channel gene set collected from wormBase, 65 genes were identified, including members of the previously described nematode acetylcholine receptor classes (deg-3 ,acr-16 , unc-29 and unc-38 ) (A. Coghlan et al., 2018). We predicted excretory/secretory proteins (EPs) of B. schroederi , and at least 1,395 EPs (5.26% of total protein) with diverse functions were identified, including 1,046 conventionally secreted proteins and 349 nonconventionally secreted proteins (Supplementary Data 2d-e).