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Fig. 6. Matrix-assisted laser desorption/ionization Fourier transform mass spectrometric (MALDI-FTMS) identification of APSGFLGMRamide (CabTRP Ia) in the anterior medial quadrant of the commissural ganglion (CoG) and hemolymph. (A) CabTRP Ia in the anterior medial quadrant of the CoG. As can be seen in this mass spectrum, taken from a tissue fragment from the quadrant of the CoG containing the anterior commissural organ, a number of peaks corresponding to individual peptides are evident. These include peaks corresponding to three isoforms of orcokinin, corazonin, three FLRFamide-related peptides, two orcomyotropin-related peptides (FDAFTTGFGHS and FDAFTTGFGHN), Gly¹-SIFamide, red pigment concentrating hormone (RPCH) and the recently identified peptide HLGSLYRamide (all labeled in blue). Of particular interest is the peak at m/z 934.501 (red arrow). This m/z is identical to that of authentic CabTRP Ia (a mass measurement error of 8.56 p.p.m. from its theoretical m/z of 934.493) and confirms the presence of this peptide in the portion of the CoG containing the ACO. (B) MALDI-FTMS detection of CabTRP Ia in the hemolymph. Hemolymph extract examined via MALDI-FTMS shows an m/z peak at 934.491 (red arrow). Again, this m/z peak is characteristic of authentic CabTRP Ia (mass measurement error 2.14 p.p.m.) and strongly suggests that this peptide is a circulating hormone in C. productus. It should be noted that in both A and B there is an m/z peak that corresponds to a known electrical noise artifact in the MALDI-FTMS system used. This peak is denoted via an asterisk in both spectra.

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