Identification of a prothoracicostatic peptide in the larval brain of the silkworm, Bombyx mori. |
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Authors: | Y J Hua Y Tanaka K Nakamura M Sakakibara S Nagata H Kataoka |
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Affiliation: | Laboratory of Bioactive Substances, National Institute of Sericultural and Entomological Sciences, Ohwashi 1-2, Tsukuba, Ibaraki 305-8634, Japan. |
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Abstract: | Prothoracicotropic hormone (PTTH) stimulates ecdysteroid biosynthesis in the prothoracic gland (PG) of insects. A peptide inhibiting ecdysteroid biosynthesis in the PG was isolated from the extracts of 2,000 larval brains of the silkworm, Bombyx mori, using a protocol that included four reversed-phase high performance liquid chromatography procedures. The primary structure of this prothoracicostatic peptide (Bom-PTSP) was determined to be H-Ala-Trp-Gln-Asp-Leu-Asn-Ser-Ala-Trp-NH(2). This neuropeptide has the same sequence as Mas-MIP-I, a myoinhibitory peptide previously isolated from the ventral nerve cord of the tobacco hornworm, Manduca sexta, and is highly homologous with the N-terminal portion of vertebrate peptides of the galanin family. This peptide inhibited PTTH-stimulated ecdysteroidogenesis in the PG at both the spinning and feeding stages, which indicates that Bom-PTSP interferes with PTTH-stimulated ecdysteroidogenesis. |
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