Change in corpus allatum function during metamorphosis of the tobacco hornworm Manduca sexta: Regulation at the terminal step in juvenile hormone biosynthesis

Govindan Bhaskaran, Steven P. Sparagana, Punnee Barrera, Karl H. Dahm

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Abstract

Changes in activity of the corpora allata (CA) during larval‐pupal‐adult development of the tobacco hornworm Manduca sexta were studied by transplantation assays, measurements of in vitro juvenile hormone (JH) and JH acid synthesis, and determination of JH acid methyltransferase (JHAMT) and 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase activities. The data from these assays demonstrate that the CA cease to secrete JH by day 4 of the last larval instar (wandering stage). With regard to JH synthesis, they remain inactive throughout the prepupal, pupal, and most of the pharate adult periods. CA of females, but not of males, resume JH synthesis shortly before eclosion. The biochemical basis of the inactivation process is the loss of JHAMT activity. However, prepupal CA produce JH acids, as shown by enzyme and in vitro assays. Pupal and pharate adult CA do not synthesize JH acids although levels of HMG‐CoA reductase activity seem to remain relatively high. Radiolabeled JH was recovered from hemolymph of allatectomized prepupae that had been injected with radiolabeled JH acid. These results provide further evidence that certain peripheral tissues (eg, imaginal discs) convert JH acid secreted by the prepupal CA to JH and, thus, that JH acid is a prohormone in the prepupal period. The CA change from hormone secretion to prohormone secretion during larval‐prepupal transformation, a unique functional alteration in an endocrine gland.

Original languageEnglish (US)
Pages (from-to)321-338
Number of pages18
JournalArchives of Insect Biochemistry and Physiology
Volume3
Issue number4
DOIs
StatePublished - 1986

Fingerprint

Corpora Allata
Manduca
Juvenile Hormones
corpora allata
Tobacco
Biosynthesis
Manduca sexta
juvenile hormones
metamorphosis
biosynthesis
Acids
acids
Assays
coenzyme A
methyltransferases
Methyltransferases
Coenzyme A
synthesis
Oxidoreductases
assays

Keywords

  • corpora allata
  • HMGCoA reductase
  • JH acid
  • JH acid methyltransferase
  • juvenile hormone
  • Manduca sexta

ASJC Scopus subject areas

  • Physiology
  • Biochemistry
  • Insect Science

Cite this

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title = "Change in corpus allatum function during metamorphosis of the tobacco hornworm Manduca sexta: Regulation at the terminal step in juvenile hormone biosynthesis",
abstract = "Changes in activity of the corpora allata (CA) during larval‐pupal‐adult development of the tobacco hornworm Manduca sexta were studied by transplantation assays, measurements of in vitro juvenile hormone (JH) and JH acid synthesis, and determination of JH acid methyltransferase (JHAMT) and 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase activities. The data from these assays demonstrate that the CA cease to secrete JH by day 4 of the last larval instar (wandering stage). With regard to JH synthesis, they remain inactive throughout the prepupal, pupal, and most of the pharate adult periods. CA of females, but not of males, resume JH synthesis shortly before eclosion. The biochemical basis of the inactivation process is the loss of JHAMT activity. However, prepupal CA produce JH acids, as shown by enzyme and in vitro assays. Pupal and pharate adult CA do not synthesize JH acids although levels of HMG‐CoA reductase activity seem to remain relatively high. Radiolabeled JH was recovered from hemolymph of allatectomized prepupae that had been injected with radiolabeled JH acid. These results provide further evidence that certain peripheral tissues (eg, imaginal discs) convert JH acid secreted by the prepupal CA to JH and, thus, that JH acid is a prohormone in the prepupal period. The CA change from hormone secretion to prohormone secretion during larval‐prepupal transformation, a unique functional alteration in an endocrine gland.",
keywords = "corpora allata, HMGCoA reductase, JH acid, JH acid methyltransferase, juvenile hormone, Manduca sexta",
author = "Govindan Bhaskaran and Sparagana, {Steven P.} and Punnee Barrera and Dahm, {Karl H.}",
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T1 - Change in corpus allatum function during metamorphosis of the tobacco hornworm Manduca sexta

T2 - Regulation at the terminal step in juvenile hormone biosynthesis

AU - Bhaskaran, Govindan

AU - Sparagana, Steven P.

AU - Barrera, Punnee

AU - Dahm, Karl H.

PY - 1986

Y1 - 1986

N2 - Changes in activity of the corpora allata (CA) during larval‐pupal‐adult development of the tobacco hornworm Manduca sexta were studied by transplantation assays, measurements of in vitro juvenile hormone (JH) and JH acid synthesis, and determination of JH acid methyltransferase (JHAMT) and 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase activities. The data from these assays demonstrate that the CA cease to secrete JH by day 4 of the last larval instar (wandering stage). With regard to JH synthesis, they remain inactive throughout the prepupal, pupal, and most of the pharate adult periods. CA of females, but not of males, resume JH synthesis shortly before eclosion. The biochemical basis of the inactivation process is the loss of JHAMT activity. However, prepupal CA produce JH acids, as shown by enzyme and in vitro assays. Pupal and pharate adult CA do not synthesize JH acids although levels of HMG‐CoA reductase activity seem to remain relatively high. Radiolabeled JH was recovered from hemolymph of allatectomized prepupae that had been injected with radiolabeled JH acid. These results provide further evidence that certain peripheral tissues (eg, imaginal discs) convert JH acid secreted by the prepupal CA to JH and, thus, that JH acid is a prohormone in the prepupal period. The CA change from hormone secretion to prohormone secretion during larval‐prepupal transformation, a unique functional alteration in an endocrine gland.

AB - Changes in activity of the corpora allata (CA) during larval‐pupal‐adult development of the tobacco hornworm Manduca sexta were studied by transplantation assays, measurements of in vitro juvenile hormone (JH) and JH acid synthesis, and determination of JH acid methyltransferase (JHAMT) and 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase activities. The data from these assays demonstrate that the CA cease to secrete JH by day 4 of the last larval instar (wandering stage). With regard to JH synthesis, they remain inactive throughout the prepupal, pupal, and most of the pharate adult periods. CA of females, but not of males, resume JH synthesis shortly before eclosion. The biochemical basis of the inactivation process is the loss of JHAMT activity. However, prepupal CA produce JH acids, as shown by enzyme and in vitro assays. Pupal and pharate adult CA do not synthesize JH acids although levels of HMG‐CoA reductase activity seem to remain relatively high. Radiolabeled JH was recovered from hemolymph of allatectomized prepupae that had been injected with radiolabeled JH acid. These results provide further evidence that certain peripheral tissues (eg, imaginal discs) convert JH acid secreted by the prepupal CA to JH and, thus, that JH acid is a prohormone in the prepupal period. The CA change from hormone secretion to prohormone secretion during larval‐prepupal transformation, a unique functional alteration in an endocrine gland.

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