Two capa-genes are expressed in the neuroendocrine system of Rhodnius prolixus

CAPA-peptides have been isolated from a broad range of insect species and are typical of the neurosecretory system of the abdominal ventral nerve cord. In Rhodnius prolixus, which is known to transmit Chagas' disease, CAPA-peptides have potent antidiuretic effects. Recently, two capa-genes were isolated from this hemipteran insect; it was the first description of the occurrence of multiple capa-genes from a single insect species. The expression of peptides from one of these capa-genes was confirmed by mass spectrometry Paluzzi (2008) [10]. In this study, the abdominal neuroendocrine system of R. prolixus was screened for the occurrence of products of the second annotated capa-gene. Single nerve preparations of abdominal segmental nerves 1-3 of R. prolixus were analyzed by MALDI-TOF mass spectrometry and the products of both capa-genes were identified by tandem mass spectrometry. The co-occurrence of the different CAPA-peptides, including CAPA-precursor peptides, in all spectra from abdominal segmental nerves 1 to 3 suggests a common expression of both capa-genes in the same neuroendocrine cells. A comparison of mass spectra obtained from abdominal segmental nerves with those of the subesophageal ganglion (SEG) revealed an obvious differential processing of the CAPA-precursors within the CNS.