Protein Synthesis and Ecdysteroidogenesis in Prothoracic Glands of the Tobacco Hornworm (Manduca sexta)

Stimulation by Big Prothoracicotropic Hormone

Peter Kulesza, Chi-Ying Lee, R. Douglas Watson

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The 28-kDa size variant of prothoracicotropic hormone (big PTTH) stimulates ecdysteroidogenesis by prothoracic glands of Manduca sexta. In the present studies, big PTTH stimulated in vitro incorporation of [35S]methionine into proteins of prothoracic glands from Day 7 last instar larvae. In 2-hr incubations, big PTTH elicited an ∼2-fold increase in total protein-specific activity. The effect appeared to be tissue specific, as big PTTH had no effect on incorporation of label into proteins of control tissue (fat body). Electrophoretic separation of tissue homogenates, followed by autoradiography and densitometric analysis, revealed increased incorporation of radiolabel into numerous glandular proteins. The result suggested that the effect of big PTTH was a general stimulation of protein synthesis, not specific stimulation of a subset of glandular proteins. Big PTTH-stimulated ecdysteroidogenesis was inhibited by cyclobeximide, indicating that the increase in protein synthesis is a requisite for enhanced hormone production. Analysis of gland incubation media revealed numerous radiolabeled proteins. The effect of big PTTH on incorporation of [35Smethionine into media proteins was considerably more variable than the effect of big PTTH on tissue incorporation. The result is consistent with the hypothesis that prothoracic glands may release proteins in addition to ecdysteroids.

Original languageEnglish
Pages (from-to)448-458
Number of pages11
JournalGeneral and Comparative Endocrinology
Volume93
Issue number3
DOIs
Publication statusPublished - 1994 Jan 1

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ecdysteroidogenesis
prothoracicotropic hormone
prothoracic glands
Manduca
Manduca sexta
protein synthesis
Proteins
proteins
ecdysteroids
autoradiography
Ecdysteroids
fat body
Fat Body
methionine
Autoradiography
instars
Methionine
hormones
Larva

All Science Journal Classification (ASJC) codes

  • Animal Science and Zoology
  • Endocrinology

Cite this

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title = "Protein Synthesis and Ecdysteroidogenesis in Prothoracic Glands of the Tobacco Hornworm (Manduca sexta): Stimulation by Big Prothoracicotropic Hormone",
abstract = "The 28-kDa size variant of prothoracicotropic hormone (big PTTH) stimulates ecdysteroidogenesis by prothoracic glands of Manduca sexta. In the present studies, big PTTH stimulated in vitro incorporation of [35S]methionine into proteins of prothoracic glands from Day 7 last instar larvae. In 2-hr incubations, big PTTH elicited an ∼2-fold increase in total protein-specific activity. The effect appeared to be tissue specific, as big PTTH had no effect on incorporation of label into proteins of control tissue (fat body). Electrophoretic separation of tissue homogenates, followed by autoradiography and densitometric analysis, revealed increased incorporation of radiolabel into numerous glandular proteins. The result suggested that the effect of big PTTH was a general stimulation of protein synthesis, not specific stimulation of a subset of glandular proteins. Big PTTH-stimulated ecdysteroidogenesis was inhibited by cyclobeximide, indicating that the increase in protein synthesis is a requisite for enhanced hormone production. Analysis of gland incubation media revealed numerous radiolabeled proteins. The effect of big PTTH on incorporation of [35Smethionine into media proteins was considerably more variable than the effect of big PTTH on tissue incorporation. The result is consistent with the hypothesis that prothoracic glands may release proteins in addition to ecdysteroids.",
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Protein Synthesis and Ecdysteroidogenesis in Prothoracic Glands of the Tobacco Hornworm (Manduca sexta) : Stimulation by Big Prothoracicotropic Hormone. / Kulesza, Peter; Lee, Chi-Ying; Watson, R. Douglas.

In: General and Comparative Endocrinology, Vol. 93, No. 3, 01.01.1994, p. 448-458.

Research output: Contribution to journalArticle

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