LIFE-CYCLE EXPRESSION OF A BOMBYXIN-LIKE NEUROPEPTIDE IN THE TOBACCO HORNWORM, MANDUCA-SEXTA

Immunocytochemistry was used to investigate the developmental expressi on of the insulinlike neuropeptide bombyxin in the tobacco hornworm, M anduca sexta, A mouse monoclonal antibody raised against a synthetic p eptide corresponding to bombyxin's A-chain N-terminus was used to loca lize a bombyxin-like peptide to a group of cerebral medial neurosecret ory cells, the M-NSC IIa(2). Immunostaining was first detected on day 0 of the second larval instar, localized in the M-NSC IIa(2) somata an d in the neurohemal organ, the corpora allata (CA), By day 0 of the fo urth larval instar, the peptide was present throughout the M-NSC IIa(2 ) somata, axons, dendritic fields and CA, Between days 7 and 9 of the fifth instar, a dramatic reduction in the dendritic fields and CA stai ning occurred, suggesting the peptide is released, After day 2 of the pupal period, only M-NSC IIa(2) somata immunostained, a pattern that p ersisted through day 2 of the adult stage, The specificity of immunost aining was demonstrated by using a synthetic bombyxin peptide to block staining, These developmental data reveal times of potential Manduca bombyxin-like peptide release which should provide insight into the pe ptide's function. (C) 1997 Published by Elsevier Science Ltd.