Ecdysone titers and prothoracic gland activity during the larval-pupal development of Manduca sexta

Bollenbacher, Walter E.; Vedeckis, Wayne V.; Gilbert, Lawrence I.

doi:10.1016/0012-1606(75)90375-9

Cited by 271 publications

(57 citation statements)

References 21 publications

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“…These would perhaps be analogous to the so-called "commitment" peak(s) observed during the last larval stage of Lepidoptera (Bollenbacher et al, 1975;Riddiford, 1976;Wolfgang and Riddiford, 1986;Parlak et al, 1992;Dai et al, 1995). In moths, these transient increases in ecdysteroid titer have long been thought to initiate the re-programming of the organism for the subsequent larvalpupal metamorphic molt (see Riddiford, 1995).…”

Section: Discussionmentioning

confidence: 93%

“…Since the ecdysteroid RIA was developed over 30 years ago (Borst and O'Connor, 1972), it has been applied many times to the investigation of "molting hormone" titers during Drosophila development (Richards, 1981;Andres et al, 1993). This has been especially true for the critical third (final) larval instar when the insect must be reprogrammed so that it can undergo metamorphosis to the pupa and then the adult in response to a large surge in 20E, a phenomenon studied mainly in the Lepidoptera (Bollenbacher et al, 1975;Riddiford, 1976Riddiford, , 1995. The requisite involvement of ecdysteroid signaling in these complex processes is central to present theories of arthropod development (Ashburner et al, 1974;Yao et al, 1993;Buszczak and Segraves, 1998;Bialeccki et al, 2002;Lafont et al, 2005;Henrich, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…The number, timing, and composition of low-amplitude elevations during the feeding stage of the last (third) larval instar are of importance because one or more may be analogous to the commitment peak of Lepidoptera (Bollenbacher et al, 1975;Riddiford, 1976;Wolfgang and Riddiford, 1986;Parlak et al, 1992;Dai et al, 1995). Although relatively small, the commitment peak is of great physiological significance because it is required to re-program cells and tissues, so that when challenged by the subsequent large ecdysteroid peak, a metamorphic molt is initiated.…”

Section: Introductionmentioning

confidence: 99%

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Discrete pulses of molting hormone, 20‐hydroxyecdysone, during late larval development of Drosophila melanogaster: Correlations with changes in gene activity

Warren

Yerushalmi

Shimell

et al. 2005

Developmental Dynamics

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165

181

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Discrete pulses of molting hormone, 20‐hydroxyecdysone, during late larval development of Drosophila melanogaster: Correlations with changes in gene activity

Warren

Yerushalmi

Shimell

et al. 2005

Developmental Dynamics

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165

181

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“…(The use of 'a-ecdysone' for ecdysone and '8-ecdysone' for ecdysterone is an abuse and should be avoided. )While it appears that the secretion of ecdysone by the prothoracic glands and the inactivation of ecdysteroids vary during larval development [5,6], it has also become clear that the relative amounts of ecdysone and ecdysterone (and other ecdysteroids?) are fluctuating [7,8].…”

mentioning

confidence: 99%

Ecdysterone Biosynthesis: A Microsomal Cytochrome-P-450-Linked Ecdysone 20-Monooxygenase from Tissues of the African Migratory Locust

Durst

1978

Eur J Biochem

128

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Ecdysone 20-monooxygenase, an enzyme which convem ecdysone to ecdysterone (the major moulting hormone of insects) has been characterized in cell-free preparations of tissues from African migratory locust. The product of the reaction has been identified as ecdysterone on the basis of several microchemical derivatization and chromatographic methods.Ecdysone 20-monooxygenase activity is located primarily in the microsomal fraction which also carries NADPH cytochrome c reductase and cytochrome P-450, as shown by sucrose density gradient centrifugation.Optimal conditions for the ecdysone 20-monooxygenase assay have been determined. The enzyme has a K,,, for ecdysone of 2.7 x lo-' M and is competitively inhibited by ecdysterone Ecdysone 20-monooxygenase is a typical cytochrome P-450 linked monooxygenase : the reaction requires O2 and is inhibited by CO, an effect partially reversed by white light. The enzyme is effectively inhibited by several specific monooxygenase inhibitors and by sulfhydryl reagents, but not by cyanide ions. Ecdysone elicits a type I difference spectrum when added to oxidized microsomes.NADPH acts as preferential electron donor. The transfer of reducing equivalents proceeds through NADPH cytochrome c (P-450) reductase : ecdysone 20-monooxygenase is inhibited by cytochrome c. Both NADPH cytochrome c reductase and' ecdysone 20-monooxygenase are inhibited by NADP' and show a similar K, for NADRH.The Malpighian tubules have the highest specific activity of ecdysone 20-monooxygenase, while fat body contain most of the cytochrome P-450 and NADPH cytochrome c reductase.( K~ = 7.5 x 10-7 M).Recent studies have established the role of the prothoracic glands in the secretion of ecdysone during larval development of insects [1,2]. This steroid is however not the major moulting hormone of insect larvae. Indeed, ecdysone serves in peripheral tissues as a precursor to ecdysterone (20-hydroxyecdysone) [3] which is also biologically more potent than ecdysone in vitro in several tests of moulting hormone activity [4].Enzymes. Ecdysone 20-monooxygenase, or ecdysone, reduced flavoprotein : oxygen oxidoreductase (20-hydroxylating) (EC 1.14.14.-); NADPH-cytochrome c (P-450) reductase (EC 1.6.2.4).Trivial Names. Ecdysone, 2fi,3fl,14~~,22R,25-pentahydroxy-5p-cholest-7-en-6-one; ecdysterone or 20-hydroxy-ecdysone, 2P,3/j14a,20R,22R,25-hexahydroxy-S~-cholest-7-en-6-one. (The use of 'a-ecdysone' for ecdysone and '8-ecdysone' for ecdysterone is an abuse and should be avoided.)While it appears that the secretion of ecdysone by the prothoracic glands and the inactivation of ecdysteroids vary during larval development [5,6], it has also become clear that the relative amounts of ecdysone and ecdysterone (and other ecdysteroids?) are fluctuating [7,8]. The enzyme responsible for the conversion of ecdysone to ecdysterone, ecdysone 20-monooxygenase, thus plays a central role in the delicate hormonal balance which controls the moulting process. It was felt that a precise characterization of this enzyme was a prerequisite to studies...

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“…Samples were vortexed, centrifuged at 10000 g for 10 rain and the supernatants were collected, vacuum-dried, resuspended in 80 % methanol and stored at 20 °C until used. The amount of ecdysteroid in each sample was then measured by radioimmunoassay (RIA) using anti-ecdysone antiserum provided by W. Bollenbacher as outlined (Bollenbacher et al, 1975). The radiolabelled antigen was…”

Section: Animals and Virusesmentioning

confidence: 99%

Baculovirus replication alters hormone-regulated host development

Park¹,

Yin

Burand

1996

Journal of General Virology

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The baculovirus Lymantria dispar nuclear polyhedrosis virus interferes with insect larval development by altering the host's hormonal system. The level of haemolymph ecdysteroids, the insect moulting hormone, was found to be higher in virus-infected larvae than in uninfected controls. This was consistently observed in both fourth instars and day 5-infected fifth instars. The rate of hormone synthesis was examined by in vitro incubation of the prothoracic gland. Gland activity in virus-infected larvae was higher than controls and continued until the late stages of virus infection, even during the time that controls had ceased to secrete ecdysone after moulting. During virus replication, the prothoracic gland was observed to maintain morphological and ultrastructural characteristics indicative of ecdysone biosynthetic activities. Therefore, it is likely that the insects are no longer under the control of the normal hormonal system after virus infection. It is felt that the alteration of hormone titre and the rate of ecdysone synthesis is the result of the activity of ecdysteroid UDP-glucosyl transferase (EGT), a virus-encoded enzyme which is thought to inactivate ecdysteroids by sugar conjugation.

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Ecdysone titers and prothoracic gland activity during the larval-pupal development of Manduca sexta

Cited by 271 publications

References 21 publications

Discrete pulses of molting hormone, 20‐hydroxyecdysone, during late larval development of Drosophila melanogaster: Correlations with changes in gene activity

Discrete pulses of molting hormone, 20‐hydroxyecdysone, during late larval development of Drosophila melanogaster: Correlations with changes in gene activity

Ecdysterone Biosynthesis: A Microsomal Cytochrome-P-450-Linked Ecdysone 20-Monooxygenase from Tissues of the African Migratory Locust

Baculovirus replication alters hormone-regulated host development

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