Investigating the role of transcription factor , Trl , during germline development in the Drosophila ovary

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Lindsay L Davenport (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Oogenesis is the process by which an egg develops from undifferentiated cells in the ovary. The Drosophila melanogaster ovary is an assembly line for egg production , making it a great system to investigate initial oocyte specification and oocyte growth and maturity. Trl , GAGA factor , encodes a transcription factor that blocks repressive histones by modifying chromatin accessibility. Trl is expressed throughout the fly and during all stages of development. Trl is necessary for eye and wing development , embryogenesis , and male germ cell development in spermatogenesis. Other studies have begun to characterize Trl in oogenesis; however , the specific role Trl plays in the germline has yet to be determined. In global mutants , Trl functions in oogenesis for follicle survival , proper germ cell number , nurse cell size , oocyte fate , and oocyte localization. Since Trl is necessary for early events in fly development , homozygous null mutants are lethal , I utilized the Flippase/Flippase Recognition Target (Flp/FRT)-mediated clonal analysis and tissue-specific RNAi to investigate how Trl germline-specific mutants regulate oocyte fate in the adult fly ovary. In this study , I found that Trl is not necessary for germline stem cell maintenance. Loss of Trl in stages 2-4 and stages 7-9 results in condensed , pyknotic , fragmented nuclei in cysts , an indicator of premature cyst death. Trl13C(40) mutant cysts have a delay in Orb expression , whereas Trls2325 clones lack Orb altogether , indicating that Trl is necessary for Orb in the oocyte. However , Trl is not necessary for entry into meiosis or oocyte localization. Further , knock-down of Trl in stage 2 cysts using a germline-specific RNAi driven by OtuGal4 did not block Orb expression , suggesting that Trl is not required for oocyte maintenance. Taken together , I conclude that Trl is necessary for Orb accumulation in the oocyte before 16-cell cyst formation. Understanding the role Trl plays in the oocyte can help us understand how chromatin modification affects the critical set of conserved , developmental steps a mature oocyte must undergo. In turn , it could also help us understand these developmental steps in other species.

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Language: English

Date: 2019

Keywords

Trl

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