Peptidergic signaling in the tadpole shrimp Triops newberryi: A potential model for investigating the roles played by peptide paracrines/hormones in adaptation to environmental change

Peptides are the largest/most diverse class of molecules used by animals for chemical communication, and with their cognate receptors, are key players in modulating physiological/behavioral control systems, including those involved in adaptation to environmental change. Crustaceans have long served as models for investigating peptidergic control of physiology/behavior, and members of Notostraca, an ancient branchiopod order, have recently been proposed as models for investigating the genetic/physiological underpinnings of ecoresponsiveness; nothing is currently known about the genes/proteins underlying peptidergic signaling in any member of this crustacean taxon. Transcriptome mining is a powerful tool for peptidome prediction in crustaceans, and all large-scale discovery of crustacean peptide receptors has been achieved via transcriptomics. Here, in silico transcriptome mining was used to elucidate the peptidergic signaling systems of the tadpole shrimp Triops newberryi, a member of Notostraca. Transcripts encoding putative precursor proteins and/or receptors for 28 peptide families were identified within the T. newberryi dataset. The deduced precursor proteins included those for allatostatin A, allatostatin B, allatostatin C, allatotropin, bursicon, CCHamide, crustacean cardioactive peptide, crustacean hyperglycemic hormone, diuretic hormone 44, ecdysis-triggering hormone, eclosion hormone, elevenin, FMRFamide-like peptide, glycoprotein hormone, GSEFLamide, inotocin, insulin-like peptide, neuroparsin, neuropeptide F, orcokinin/orcomyotropin, proctolin, pyrokinin/periviscerokinin, SIFamide, sulfakinin and tachykinin-related peptide; 117 distinct mature peptides were predicted from the collective set of deduced pre/preprohormones. Transcripts encoding putative receptors for most of the abovementioned peptide groups were also identified from the T. newberryi assembly, as were those for several families for which no precursors were found, i.e., corazonin, RYamide and short neuropeptide F. This is the first description of a peptidome and peptide receptors from any member of the Notostraca, and as such, provide a foundation for beginning to investigate the roles played by peptidergic signaling systems in T. newberryi and other notostracans, including how they may contribute to modulating organism-environment interactions.