Biosynthetic products of the corpus allatum of the tobacco hornworm, Manduca sexta

Abstract

With the single exception of the discovery of juvenile hormone (JH) acid as a major product of the corpus allatum (CA), research on the biosynthetic output of this endocrine gland has focused primarily on its biologically active products, the JHs. Results from this laboratory suggest the existence of another, JH-related product, which is biosynthesized in vitro by the CA of Manduca sexta and of at least two other Lepidoptera. This substance is not recognized by antibodies highly specific for the JHs and their acids, but when it is hydrolyzed by esterases, it yields JH III acid. Thus a portion of its structure appears to be ester-linked JH III acid. A similar effect was obtained with a variety of lipases, suggesting that this product may be an acylglycerol. Some of the product is stored in the CA, and its synthesis/release is partially inhibited by fluoromevalonate. Male and female CA from last instars synthesize/release equivalent amounts of this product until after wandering on day 5, when female CA synthesize/release significantly more. Preliminary evidence suggests this product also exists in the hemolymph. Treatment of CA products in vitro with enzymes other than esterases and lipases revealed an effect of β-glucuronidase, suggesting the existence of a JH III (acid)-glucuronide. The possible relationship of these products to JH III catabolism, transport, storage and secretion must now be considered. © 1995.