Temporal changes in DNA synthesis of prothoracic gland cells during larval development and their correlation with ecdysteroidogenic activity in the silkworm, Bombyx mori
Article first published online: 17 MAR 2005
Copyright © 2005 Wiley-Liss, Inc., A Wiley Company
Journal of Experimental Zoology Part A: Comparative Experimental Biology
Volume 303A, Issue 4, pages 249–258, 1 April 2005
How to Cite
Gu, S.-H. and Chow, Y.-S. (2005), Temporal changes in DNA synthesis of prothoracic gland cells during larval development and their correlation with ecdysteroidogenic activity in the silkworm, Bombyx mori. J. Exp. Zool., 303A: 249–258. doi: 10.1002/jez.a.142
- Issue published online: 17 MAR 2005
- Article first published online: 17 MAR 2005
- Manuscript Accepted: 28 OCT 2004
- Manuscript Received: 24 OCT 2004
- National Science Council. Grant Numbers: NSC 91–2311–B–178–001, 92–2313–B–178–001, 92–2311–B–178–002, 93–2313–B–178–002, 93–2313–B–178–003
- National Museum of Natural Science of the R.O.C.
DNA synthesis in prothoracic gland cells of the silkworm, Bombyx mori, was studied immunocytochemically after in vivo labeling with 5–bromo–2'–deoxyuridine (BrdU), and its developmental changes during the 3rd, 4th, and last larval instars were examined. During the early stages of both the 3rd and 4th larval instars, a dramatic increase in the number of DNA-synthesizing cells of the prothoracic glands was detected. However, during the latter stages of each instar, the number of DNA-synthesizing cells greatly decreased. The determination of glandular protein content showed that dramatic increases occurred during the latter stages of each larval instar. Comparison of changes in prothoracic gland cell DNA synthesis with ecdysteroidogenic activity showed that the increase in DNA synthesis precedes ecdysteroidogenesis. The cellular mechanism underlying changes in prothoracic gland cell DNA synthesis during the last two larval instars was further analyzed by determining the in vitro DNA synthesis of the glands, their responsiveness to hemolymph growth factors, and changes in the growth-promoting activity of hemolymph during development. It was found that both growth factors and the responsiveness of the prothoracic gland cells to growth factors from hemolymph may play roles in regulating DNA synthesis of gland cells. J. Exp. Zool. 303A:249–258, 2005. © 2005 Wiley-Liss, Inc.