Pyrokinin neuropeptides in a crustacean - Isolation and identification in the white shrimp Penaeus vannamei

Identification of substances able to elicit physiological or behavioural pr ocesses that are related to reproduction would greatly contribute to the do mestication of commercially important crustaceans that do not reproduce eas ily in captivity. Crustaceans are thought to release urine signals used for chemical communication involved in courtship behaviour. In contrast to ins ects, very little is known about the endocrinological processes underlying this phenomenon. Therefore, an extract of 3500 central nervous systems of f emale white shrimp Penaeus vannamei was screened for myotropic activity in order to purify pyrokinin-like peptides that belong to the pyrokinin/PBAN n europeptide family. Members of this family regulate reproductive processes in insects, including pheromone biosynthesis. Purification of these pyrokin ins was achieved by a combination of reversed-phase and normal-phase chroma tography. Subsequent characterization by mass spectrometry, Edman degradati on and peptide synthesis resulted in the elucidation of two novel peptides. Pev-PK 1 has the primary sequence DFAFSPRL-NH2 and a second peptide (Pev-P K 2) is characterized as the nonapeptide ADFAFNPRL-NH2. Pev-PK 1 contains t he typical FXPRL-NH2 (X = G, S, T or V) C-terminal sequence that characteri zes members of the versatile pyrokinin/PBAN family. Pev-PK 2 displays an As n residue at the variable X position of the core pyrokinin sequence. These crustacean pyrokinins are the first to be found in a noninsect. The synthet ic peptides display myotropic activity on the Leucophaea maderae as well as on the Astacus leptodactylus hindgut.