In vivo analysis of the GFP pattern of expression driven by the BhC4-1 ring gland enhancer at the end of the embryonic development in D. melanogaster transgenic lines

Abstract

Our laboratory investigates the molecular mechanisms that promote developmentally regulated patterns of gene expression in eukaryotes. As a model, we employ the BhC4-1 DNA puff gene, which is amplified and expressed in a developmentally regulated manner at the end of the fourth larval instar of B. hygida. The functional analyses of the BhC4-1 promoter region lead to the identification of cis-regulatory elements. One of these elements constitutes the 67 bp ring gland enhancer (-253/-187) which drives ring gland expression at the end of embryonic development. The Drosophila ring gland is a compound endocrine organ that comprises the prothoracic glands, the corpus allatum, and the corpus cardiac. Recent data derived from the histological analysis indicate that the ring gland enhancer drives Bhc4-1-lacZ expression specifically to the prothoracic glands. In addition, data derived from in situ hybridization experiments suggest that the BhC4-1-lacZ mRNA expression can be detected at developmental times prior to the ring gland formation in cells localized in the anterior region of the embryo, which possibly is destined to the prothoracic glands. In this context, this project aims to obtain D. melanogaster transgenic lines transformed with a (-253/+40)/GFP construct in which the ring gland enhancer will be placed upstream of the GFP reporter gene. The pattern of GFP expression in the transgenic lines will be analyzed through fluorescence microscopy. With this analysis, we aim the detection of GFP expression in cells that constitute precursors of the prothoracic glands, which will enable us to follow the migration of these cells and their fusion with the other cells that are part of the ring gland. This project is potentially interesting because even though the ring gland constitutes the main larval endocrine organ, a description of its embryonic origin is still incomplete, particularly in what concerns the formation of the prothoracic glands.(AU)