A genome‐wide survey across 10 species from algae Guillardia theta to mammals revealed that Caenorhabditis elegans and Caenorhabditis briggsae acquired a large number of glycine‐rich secreted peptides (GRSPs, 110 GRSPs in C. elegans and 93 in C. briggsae) during evolution in this study. Chromosomal mapping indicated that most GRSPs were clustered on their genomes [103 (93.64%) in C. elegans and 82 (88.17%) in C. briggsae]. Totally, there are 18 GRSPs cluster units in C. elegans and 13 in C. briggsae. Except for four C. elegans where GRSP clusters lacking matching clusters in C. briggsae, all other GRSP clusters had its corresponding orthologous clusters between the two nematodes. Using eight transcriptomic datasets of Affmyetrix microarray, genome‐wide association studies identified many co‐expressed GRSPs clusters after C. elegans infections. Highly homologous coding sequences and conserved exon‐intron organizations indicated that GRSP tight clusters might have originated from local DNA duplications. The conserved synteny blocks of GRSP clusters between their genomes, the co‐expressed GRSPs clusters after C. elegans infections, and a strong purifying selection of protein‐coding sequences suggested evolutionary constraint acting on C. elegans to ensure that C. elegans could rapidly launch and fulfill systematic responses against infections by co‐expression, co‐regulation, and co‐functionality of GRSP clusters.
Part of the book: Nematology