Exploring the Sexual Dimorphism of Crustacean Neuropeptide Expression Using Callinectes sapidus as a Model Organism.

The impact of numerous diseases has been linked to differences in sex between organisms, including various neurological diseases. As neuropeptides are known to be key players in the nervous system, studying the variation of neuropeptidomic profiles between males and females in a crustacean model organism is of interest. By using high-resolution mass spectrometry with two complementary ionization sources in conjunction with quantitative chemical labeling (isotopic reductive dimethylation), differences were observed in five key neural tissues and hemolymph. Interestingly, while males and females possess numerous neuropeptide isoforms that are unique to their sex, the represented families of each sex remain largely consistent. However, some differences in familial isoforms were also observed, such as the relative numbers of neuropeptides belonging to RFamide and allatostatin A-type families. Additionally, >100 neuropeptides detected across five neural tissues and hemolymph were found to have statistically significant differences in abundance between male and female blue crab samples. Also, hundreds of putative peptide sequences were identified by de novo sequencing that may be indicative of previously undiscovered neuropeptides, highlighting the power of using a multifaceted MS approach.