Abstract
Steroid hormones regulate life stage transitions, allowing animals to appropriately follow a developmental timeline. During insect development, the steroid hormone ecdysone is synthesized and released in a regulated manner by the prothoracic gland (PG) and then hydroxylated to the active molting hormone, 20-hydroxyecdysone (20E), in peripheral tissues. We manipulated ecdysteroid titers, through temporally controlled over-expression of the ecdysteroid-inactivating enzyme, CYP18A1, in the PG using the GeneSwitch-GAL4 system in the fruit fly Drosophila melanogaster. We monitored expression of a 20E-inducible glue protein gene, Salivary gland secretion 3 (Sgs3), using a Sgs3:GFP fusion transgene. In wild type larvae, Sgs3-GFP expression is activated at the midpoint of the third larval instar stage in response to the rising endogenous level of 20E. By first knocking down endogenous 20E levels during larval development and then feeding 20E to these larvae at various stages, we found that Sgs3-GFP expression could be triggered at an inappropriate developmental stage after a certain time lag. This stage-precocious activation of Sgs3 required expression of the Broad-complex, similar to normal Sgs3 developmental regulation, and a small level of nutritional input. We suggest that these studies provide evidence for a tissue-autonomic regulatory system for a metamorphic event independent from the primary 20E driven developmental progression.
Original language | English (US) |
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Pages (from-to) | 166-176 |
Number of pages | 11 |
Journal | Developmental Biology |
Volume | 430 |
Issue number | 1 |
DOIs | |
State | Published - Oct 1 2017 |
Bibliographical note
Funding Information:We thank KYOTO Stock Center (DGRC) in Kyoto Institute of Technology and Bloomington Drosophila Stock Center for stocks. The antibodies were obtained from the Developmental Studies Hybridoma Bank, created by the NICHD of the NIH and maintained at The University of Iowa. We thank B.H. white and L. Zong for providing vectors. We thank J. Saito for comments on the manuscript. HO was partly supported by JSPS KAKENHI Grant Number 26450466 and the Asahi Glass Foundation . MJS and MBO were partially supported by a grant from NIGMS ( R35-GM118029 to MBO). Appendix A
Publisher Copyright:
© 2017 Elsevier Inc.
Keywords
- Broad Complex
- Developmental checkpoint
- Drosophila melanogaster
- Salivary gland
- Salivary gland secretion 3
- Steroid hormone