Characterizing the role of the Early Gene at 23 (E23) in Drosophila Melanogaster Oogenesis

Abstract

Drosophila melanogaster (fruit fly) females undergo oogenesis to create oocytes from undifferentiated stem cells in the ovary. Similar to estrogen in humans, the steroid hormone ecdysone in fruit flies has a known role in facilitating oogenesis. The ecdysone signaling pathway is highly studied as it can help us draw parallels between Drosophila and human reproductive processes. After ecdysone binds to an ecdysone receptor (EcR), EcR activates transcription of many genes, such as E74, E75, and E78. These early genes code for proteins that are essential for Drosophila tissue repair, development, and reproduction. One of the early genes, the Early Gene at 23 (E23), is thought to be a target of ecdysone signaling, but little is known about its function. Because E23 is expressed in multiple cell types and highly expressed in Drosophila ovaries, we hypothesize that E23 plays a role in Drosophila viability, reproduction, and oogenesis. To determine the role of E23 in Drosophila viability and reproduction, flies harboring transposable element insertions in the E23 locus were analyzed for potential mutant phenotypes. Our experiments using these lines suggested that E23 is not needed for viability or fertility. We also tested whether E23 affects oogenesis in more subtle ways, using high-resolution confocal microscopy, but results indicate that it does not affect early oogenesis or adult stem cell numbers. Although E23 does not play a role in Drosophila oogenesis, it may have other important functions within the fly.