Capacity of Insect (Manduca sexta) Prothoracic Glands to Secrete Ecdysteroids: Relation to Glandular Growth

Chi Ying Lee, Kara J. Lee, Phillip H. Chumley, Collin J. Watson, Amiraht Abdur-Rahman, R. Douglas Watson

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The capacity of prothoracic glands to secrete ecdysteroids changes during the last larval stadium of the tobacco hornworm, Manduca sexta. In the present study, the protein content of prothoracic glands was observed to change significantly during this time period. Peaks in glandular protein content occurred on Day 4 (15.4 μg/gland) and Day 7 (14.6 μg/gland). These correspond to times of maximal ecdysteroid secretion in vitro. Ecdysteroid secretion in vitro was determined as a function of glandular protein content for Day 1, 3, and 7 glands. For unstimulated glands, secretion increased from 0.05 ng/μg on Day 1, to 0.54 ng/μg on Day 3, to 1.37 ng/μg on Day 7. For glands incubated with big PTTH, secretion increased from 0.27 ng/μg on Day 1, to 2,05 ng/μg on Day 3, to 2.60 ng/μg on Day 7. The results suggested that developmental changes in secretory capacity are influenced by both the amount and type of glandular proteins. Glandular protein metabolism was assessed by monitoring the incorporation of [35S]methionine. A time course study revealed the rate of incorporation for Day 3 and Day 5 glands was significantly greater than the rate for Day 1 and Day 7 glands. Electrophoretic separation of radiolabeled glandular proteins revealed developmental changes in the pattern of protein synthesis. However, a band whose intensity changed in parallel with developmental changes in glandular secretory capacity was not detected. Finally, incorporation of BrdU by cells of the prothoracic glands was assessed using immunohistochemistry: Incorporation of BrdU was not observed on Days 1 or 7, occurred in only a few cells on Day 5, and was most pronounced on Day 3 (12.3% of the cells were labeled). The combined results indicate that changes in ecdysteroidogenic capacity are associated with (a) a change in glandular protein content, (b) a change in the types of proteins synthesized by prothoracic glands, and (c) a temporally restricted pulse of DNA synthesis. the latter being a possible indicant of cell proliferation.

Original languageEnglish
Pages (from-to)404-412
Number of pages9
JournalGeneral and Comparative Endocrinology
Volume100
Issue number3
DOIs
Publication statusPublished - 1995 Dec

Fingerprint

Ecdysteroids
prothoracic glands
Manduca
ecdysteroids
Manduca sexta
Insects
protein content
secretion
insects
Growth
Proteins
proteins
cells
protein metabolism
Bromodeoxyuridine
immunohistochemistry
methionine
cell proliferation
protein synthesis
synthesis

All Science Journal Classification (ASJC) codes

  • Animal Science and Zoology
  • Endocrinology

Cite this

Lee, Chi Ying ; Lee, Kara J. ; Chumley, Phillip H. ; Watson, Collin J. ; Abdur-Rahman, Amiraht ; Watson, R. Douglas. / Capacity of Insect (Manduca sexta) Prothoracic Glands to Secrete Ecdysteroids : Relation to Glandular Growth. In: General and Comparative Endocrinology. 1995 ; Vol. 100, No. 3. pp. 404-412.
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abstract = "The capacity of prothoracic glands to secrete ecdysteroids changes during the last larval stadium of the tobacco hornworm, Manduca sexta. In the present study, the protein content of prothoracic glands was observed to change significantly during this time period. Peaks in glandular protein content occurred on Day 4 (15.4 μg/gland) and Day 7 (14.6 μg/gland). These correspond to times of maximal ecdysteroid secretion in vitro. Ecdysteroid secretion in vitro was determined as a function of glandular protein content for Day 1, 3, and 7 glands. For unstimulated glands, secretion increased from 0.05 ng/μg on Day 1, to 0.54 ng/μg on Day 3, to 1.37 ng/μg on Day 7. For glands incubated with big PTTH, secretion increased from 0.27 ng/μg on Day 1, to 2,05 ng/μg on Day 3, to 2.60 ng/μg on Day 7. The results suggested that developmental changes in secretory capacity are influenced by both the amount and type of glandular proteins. Glandular protein metabolism was assessed by monitoring the incorporation of [35S]methionine. A time course study revealed the rate of incorporation for Day 3 and Day 5 glands was significantly greater than the rate for Day 1 and Day 7 glands. Electrophoretic separation of radiolabeled glandular proteins revealed developmental changes in the pattern of protein synthesis. However, a band whose intensity changed in parallel with developmental changes in glandular secretory capacity was not detected. Finally, incorporation of BrdU by cells of the prothoracic glands was assessed using immunohistochemistry: Incorporation of BrdU was not observed on Days 1 or 7, occurred in only a few cells on Day 5, and was most pronounced on Day 3 (12.3{\%} of the cells were labeled). The combined results indicate that changes in ecdysteroidogenic capacity are associated with (a) a change in glandular protein content, (b) a change in the types of proteins synthesized by prothoracic glands, and (c) a temporally restricted pulse of DNA synthesis. the latter being a possible indicant of cell proliferation.",
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Capacity of Insect (Manduca sexta) Prothoracic Glands to Secrete Ecdysteroids : Relation to Glandular Growth. / Lee, Chi Ying; Lee, Kara J.; Chumley, Phillip H.; Watson, Collin J.; Abdur-Rahman, Amiraht; Watson, R. Douglas.

In: General and Comparative Endocrinology, Vol. 100, No. 3, 12.1995, p. 404-412.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Capacity of Insect (Manduca sexta) Prothoracic Glands to Secrete Ecdysteroids

T2 - Relation to Glandular Growth

AU - Lee, Chi Ying

AU - Lee, Kara J.

AU - Chumley, Phillip H.

AU - Watson, Collin J.

AU - Abdur-Rahman, Amiraht

AU - Watson, R. Douglas

PY - 1995/12

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N2 - The capacity of prothoracic glands to secrete ecdysteroids changes during the last larval stadium of the tobacco hornworm, Manduca sexta. In the present study, the protein content of prothoracic glands was observed to change significantly during this time period. Peaks in glandular protein content occurred on Day 4 (15.4 μg/gland) and Day 7 (14.6 μg/gland). These correspond to times of maximal ecdysteroid secretion in vitro. Ecdysteroid secretion in vitro was determined as a function of glandular protein content for Day 1, 3, and 7 glands. For unstimulated glands, secretion increased from 0.05 ng/μg on Day 1, to 0.54 ng/μg on Day 3, to 1.37 ng/μg on Day 7. For glands incubated with big PTTH, secretion increased from 0.27 ng/μg on Day 1, to 2,05 ng/μg on Day 3, to 2.60 ng/μg on Day 7. The results suggested that developmental changes in secretory capacity are influenced by both the amount and type of glandular proteins. Glandular protein metabolism was assessed by monitoring the incorporation of [35S]methionine. A time course study revealed the rate of incorporation for Day 3 and Day 5 glands was significantly greater than the rate for Day 1 and Day 7 glands. Electrophoretic separation of radiolabeled glandular proteins revealed developmental changes in the pattern of protein synthesis. However, a band whose intensity changed in parallel with developmental changes in glandular secretory capacity was not detected. Finally, incorporation of BrdU by cells of the prothoracic glands was assessed using immunohistochemistry: Incorporation of BrdU was not observed on Days 1 or 7, occurred in only a few cells on Day 5, and was most pronounced on Day 3 (12.3% of the cells were labeled). The combined results indicate that changes in ecdysteroidogenic capacity are associated with (a) a change in glandular protein content, (b) a change in the types of proteins synthesized by prothoracic glands, and (c) a temporally restricted pulse of DNA synthesis. the latter being a possible indicant of cell proliferation.

AB - The capacity of prothoracic glands to secrete ecdysteroids changes during the last larval stadium of the tobacco hornworm, Manduca sexta. In the present study, the protein content of prothoracic glands was observed to change significantly during this time period. Peaks in glandular protein content occurred on Day 4 (15.4 μg/gland) and Day 7 (14.6 μg/gland). These correspond to times of maximal ecdysteroid secretion in vitro. Ecdysteroid secretion in vitro was determined as a function of glandular protein content for Day 1, 3, and 7 glands. For unstimulated glands, secretion increased from 0.05 ng/μg on Day 1, to 0.54 ng/μg on Day 3, to 1.37 ng/μg on Day 7. For glands incubated with big PTTH, secretion increased from 0.27 ng/μg on Day 1, to 2,05 ng/μg on Day 3, to 2.60 ng/μg on Day 7. The results suggested that developmental changes in secretory capacity are influenced by both the amount and type of glandular proteins. Glandular protein metabolism was assessed by monitoring the incorporation of [35S]methionine. A time course study revealed the rate of incorporation for Day 3 and Day 5 glands was significantly greater than the rate for Day 1 and Day 7 glands. Electrophoretic separation of radiolabeled glandular proteins revealed developmental changes in the pattern of protein synthesis. However, a band whose intensity changed in parallel with developmental changes in glandular secretory capacity was not detected. Finally, incorporation of BrdU by cells of the prothoracic glands was assessed using immunohistochemistry: Incorporation of BrdU was not observed on Days 1 or 7, occurred in only a few cells on Day 5, and was most pronounced on Day 3 (12.3% of the cells were labeled). The combined results indicate that changes in ecdysteroidogenic capacity are associated with (a) a change in glandular protein content, (b) a change in the types of proteins synthesized by prothoracic glands, and (c) a temporally restricted pulse of DNA synthesis. the latter being a possible indicant of cell proliferation.

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