Abstract
It is generally accepted that the prothoracic glands of insects produce ecdysone, which is converted by a 20-monooxygenase in peripheral tissues to the major molting hormone, 20-hydroxyecdysone. Incubation in vitro of the prothoracic glands of larval or pupal Manduca sexta in the presence of a hemolymph protein fraction (HPF) increased the ecdysteroid content of the medium almost 8-fold. A comparable increase was noted when HPF was added to medium preconditioned with prothoracic glands but from which the glands had been removed. We used a differential RIA to show that a major product of the prothoracic glands in vitro cross-reacts with antiserum (20-hydroxyecdysone-2-succinylthyroglobulin amide; H-2) that retains affinity to ecdysteroids having a modified A ring. However, this product did not bind to antiserum (ecdysone-22-succinylthyroglobulin amide; H-22) that has affinity mainly for ecdysteroids modified at the side chain. We employed radiolabeled precursor studies with prothoracic glands in vitro and a combination of analytical techniques (NMR, CD, MS) to demonstrate that the major ecdysteroid release from the glands is a mixture of 2-dehydroecdysone and 3-dehydroecdysone (1:2), which is rapidly reduced to ecdysone in the presence of HPF. We postulate that the active component of HPF is 3 beta 3 beta (2 beta)-formin-3(2)-ketoecdysteroid reductase. These results may explain several anomalous observations pertaining to the molting of insect fragments in the absence of prothoracic glands and suggest a complex system for the control of insect molting and metamorphosis.
Full text
PDF




Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bardin C. W., Bullock L. P., Mowszowicz I. Androgen metabolism and receptor activity in preputial glands and kidneys of normal and androgen-insenitive tfm rats and tfm/y mice. Methods Enzymol. 1975;39:454–460. doi: 10.1016/s0076-6879(75)39040-x. [DOI] [PubMed] [Google Scholar]
- Chino H., Sakurai S., Ohtaki T., Ikekawa N., Miyazaki H., Ishibashi M., Abuki H. Biosynthesis of agr-Ecdysone by Prothoracic Glands in vitro. Science. 1974 Feb 8;183(4124):529–530. doi: 10.1126/science.183.4124.529. [DOI] [PubMed] [Google Scholar]
- Dinan L., Rees H. H. Preparation of 3-epi-ecdysone and 3-epi-20-hydroxyecdysone. Steroids. 1978 Dec;32(5):629–638. doi: 10.1016/0039-128x(78)90073-9. [DOI] [PubMed] [Google Scholar]
- Karlson P., Bugany H., Döpp H., Hoyer G. A. 3-Dehydroecdyson, ein Stoffwechselprodukt des Ecdysons bei der Schmiessfliege Calliphora erythrocephala Meigen. Hoppe Seylers Z Physiol Chem. 1972 Oct;353(10):1610–1614. [PubMed] [Google Scholar]
- King D. S., Bollenbacher W. E., Borst D. W., Vedeckis W. V., O'connor J. D., Ittycheriah P. I., Gilbert L. I. The Secretion of alpha-Ecdysone by the Prothoracic Glands of Manduca sexta In Vitro. Proc Natl Acad Sci U S A. 1974 Mar;71(3):793–796. doi: 10.1073/pnas.71.3.793. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Koolman J., Spindler K. D. Enzymatic and chemical synthesis of 3-dehydroecdysterone, a metabolite of the moulting hormone of insects. Hoppe Seylers Z Physiol Chem. 1977 Oct;358(10):1339–1344. doi: 10.1515/bchm2.1977.358.2.1339. [DOI] [PubMed] [Google Scholar]
- Nakanishi K. The ecdysones. Pure Appl Chem. 1971;25(1):167–195. doi: 10.1351/pac197125010167. [DOI] [PubMed] [Google Scholar]
- Spindler K. D., Koolman J., Mosora F., Emmerich H. Catalytical oxidation of ecdysteroids to 3-dehydro products and their biological activities. J Insect Physiol. 1977;23(4):441–444. doi: 10.1016/0022-1910(77)90253-0. [DOI] [PubMed] [Google Scholar]