ISSN:0739-4462    

DOI:10.1002/arch.940100302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe prothoracic glands ofManduca sextasynthesize dehydroecdysone, which is rapidly converted to ecdysone through the mediation of a hemolymph enzyme, a 3 β‐forming‐3‐ketosteroid reductase. The hemolymph protein fraction (HPF) containing this enzyme was obtained from diapausing and non‐diapausing pupae, isolated abdomens, surgically manipulated pupae, etc., and in all cases had the capacity to affect the conversion of dehydroecdysone to ecdysone. The enzyme is heat labile, is inactivated by trypsin, and has a molecular weight of between 20,000 and 30,000. The data indicate that the conversion of dehydroecdysone to ecdysone exhibits linear kinetics and may be dependent on both the enzyme concentration and the concentration of NADPH at the beginning of the reaction but may be limited by the absolute amount of reducing equivalents after 10 min, under the experimental conditions utilized. The capacity of the enzyme to reduce dehydroecdysone was titered in the hemolymph during the last larval instar and during prepupal and pupal life with maximum capacity exhibited at the beginning of the instar, on day 8 of larval life and at day 1 of pupal life. Even at its lowest point at day 5, 1 ml of hemolymph was able to convert 77 pmol (∼35 ng) dehydroecdysone to ecdysone in 1 min. These results require a new interpretation of the control of molting in the L

ISSN:0739-4462    

DOI:10.1002/arch.940100303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractSeveral 3‐dehydro‐ (or 3‐oxo‐) ecdysteroids have been prepared by enzymatic and/or chemical means. Methods for their purification using various high‐performance liquid chromatography systems are described. Proton and carbon nuclear magnetic resonance analyses show that 3‐dehydroecdysteroids when dissolved in water or methanol (but not in chloroform) present a temperature‐dependent equilibrium between two forms. The possible structure of these two forms

ISSN:0739-4462    

DOI:10.1002/arch.940100304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractTwo kinds of storage proteins (SP‐1, SP‐2) were confirmed in hemolymph and fat body ofPieris rapaeduring metamorphosis. Both proteins were present in high concentrations in the hemolymph during the last larval instar. Hemolymph concentrations of SP‐1 and SP‐2 dropped after pupation as the proteins were being deposited in fat bodies. SP‐2 is present in a larger amount than SP‐1. Detailed studies on storage proteins determined their properties, mode of synthesis, and accumulation in the fat body.SP‐1 has a molecular weight of 500,000 and consists of one type of subunit (Mr77,000), while SP‐2 has a molecular weight of 460,000 and is composed of two types of subunits (Mr80,000 and 69,000). The pl values of SP‐1 and SP‐2 were determined to be 6.97 and 7.06, respectively.Fat body cells from 1‐day‐old fifth instar larvae synthesized storage proteins in large amounts, whereas those from late prepupae exhibited high protein sequestration. Proteins taken up in fat body accumulated in dense granules during the pupal stage but sharply decreased at the adult stage.Morphological changes in the fat body tissues were observed during the larval‐pupal transformation; the nuclei of fat body cells became irregularly shaped, and the boundaries between cells seemed to be obscure. Synthesis, storage, or degradation of storage proteins in fat body during development is closely associated with morphologic

ISSN:0739-4462    

DOI:10.1002/arch.940100305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractDiptericin A is a member of a multigenic family of antibacterial peptides that are synthesized by larvae ofPhormia terranovae(Diptera) in response to a bacterial injection or to injury. The 82‐residue peptide is active only against a limited range of Gram‐negative bacteria. Data presented suggest that the primary action of diptericin A is on the cytoplasmic membrane of growing bacte

ISSN:0739-4462    

DOI:10.1002/arch.940100306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractEvidence is presented for the reversible activation‐inactivation of the microsomal ecdysone 20‐monooxygenase from fat body of the cotton leafworm,Spodoptera littoralis, in a manner commensurate with reversible changes in its phosphorylation state. The activity of the monooxygenase was higher following preincubation with fluoride (an inhibitor of phosphoprotein phosphatases) than in its absence. Preincubation with alkaline phosphatase or with cAMP‐dependent protein kinase resulted in appreciable diminution or enhancement, respectively, in monooxygenase activity. Activation of ecdysone 20‐monooxygenase activity could also be effected by incubation with a cytosolic fraction in the presence of cAMP, ATP, and fluoride; this activation was prevented by a cAMP‐dependent protein kinase inhibitor. Similarly, inactivation of the monooxygenase was achieved by preincubation with cytosol, the effect being enhanced by Ca2+‐calmodulin or by Mg2+ions. The combined results provide indirect evidence that the microsomal ecdysone 20‐monooxygenase exists in an active phosphorylated form and an inactive dephosphorylated form, interconvertible by a cAMP‐dependent protein kinase and a phosphoprot

ISSN:0739-4462    

DOI:10.1002/arch.940100307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractFifth (last) instar nymphs of th e tick Ornithodoros moubata convert ingested 20‐hydroxyecdysone (20E) to apolar conjugates AP2, which are then converted to th e more polar conjugates API. Only small quantities of free hormone were transferred to th e hemolymph and the carcass within t h e first 2 days after the blood meal. The proportion of radiolabel in these two compartments was highest at the time of the endogenous ecdysteroid peak; however, no traces of free [3H]20E were detected. The conversion probably occurs principally in the intestinal cells. Eleven days after ingestion, 84% of the radiolabel is located in the digestive tract, mainly in the form of API conjugates.API obtained in second instar nymphs fed with [3H]ecdysone ([3H]E) remain stable throughout the following nymphal instars. The ecdysteroid moiety of APT remained unchanged. The hydrolysis, although not complete, always yielded a peak comigrating with the reference E but never 20E or any other clearly distinct peaks that may have corresponded to metabolites of 20E. Less label per individual was present in adults, but its nature remained the same, viz., API mainly located in the digestive tract. In females, 2.5% of the label was transferred to the progeny during the first ovipositional cycle.Apolar products (mainly AP2) that accumulated in eggs of females injected with [3H]E or [3H]20E during vitellogenesis remained unchanged during the whole embryonic development. During the molting cycle of larvae, there was only a slight conversion of AP2 to API, but esterase hydrolysis of these products released the same percentages of E and 20E as in the freshly laid eggs.We conclude that in this tick species apolar conjugates of ecdysteroids are inactivation metabolites that are not reutilized during the development of the animal. These metabolites are mainly retained in the tick, probably because of its peculiar blocked midgut. Several studies have shown that in other arthropod species (ticks, spiders, and insects), these apolar metabolites are excreted in the fece

ISSN:0739-4462    

DOI:10.1002/arch.940100308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY