The Genome of the Marine Rotifer Brachionus manjavacas : Genome-Wide Identification of 310 G Protein-Coupled Receptor (GPCR) Genes

The marine rotifer Brachionus manjavacas is widely used in ecological, ecotoxicological, and ecophysiological studies. The reference genome of B. manjavacas is a good starting point to uncover the potential molecular mechanisms of responses to various environmental stressors. In this study, we assembled the whole-genome sequence (114.1 Mb total, N50 = 6.36 Mb) of B. manjavacas , consisting of 61 contigs with 18,527 annotated genes. To elucidate the potential ligand–receptor signaling pathways in marine Brachionus rotifers in response to environmental signals, we identified 310 G protein-coupled receptor (GPCR) genes in the B. manjavacas genome after comparing them with three other species, including the minute rotifer Proales similis , Drosophila melanogaster , and humans ( Homo sapiens ). The 310 full-length GPCR genes were categorized into five distinct classes: A (262), B (26), C (7), F (2), and other (13). Most GPCR gene families showed sporadic evolutionary processes, but some classes were highly conserved between species as shown in the minute rotifer P. similis . Overall, these results provide potential clues for in silico analysis of GPCR-based signaling pathways in the marine rotifer B. manjavacas and will expand our knowledge of ligand–receptor signaling pathways in response to various environmental signals in rotifers.