Figure 3.

Representative MALDI-TOF/TOF mass spectrum of isotopic formaldehyde labeled mixture of brain extracts from fed and unfed crabs. Three crab brains were used to make each extract. Sample from unfed crabs was labeled with FH₂ and sample from fed crabs was labeled with FD₂. The heavy labeled peaks are indicated with open circles, and the light labeled peaks are indicated with closed circles. The peak pairs from several abundant neuropeptides are indicated and labeled with their corresponding amino acid sequences.