Regulation of gene expression during Drosophila oocyte development

• Autor(a) principal: Matos, Ricardo
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/16694
• topic: Drosófila; Oogénese; dkdm5; Meiose; Synaptonemal complex

Human oocytes can stay dormant for several decades in meiotic arrest, before reactivation and maturation. Similar, Drosophila oocyte is mostly transcriptionally quiescent during prophase I-arrest, transiently reactivating gene expression just before it progresses into metaphase I. Our aim is to better understand such reactivation and its role for oocyte maturation and female fertility. This work is divided in 3 chapters. In chapter I we use an isolated loss of function allele of dkdm5 to characterize the function of this enzyme during oogenesis. The results obtained with the loss of function allele of dkdm5 are consistent, albeit stronger, with the phenotypes previously observed after RNAi depletion and hypomorphic allele of dkdm5. Yet, a qualitatively distinct phenotype has also been identified, suggesting a new function of dkdm5 during oocyte maturation. In chapter II we try to access chromatin quality and synaptonemal complex assembly throughout oocyte development. Proteins from chromatin remodelling complexes, as dkdm5, have been shown to disrupt the synaptonemal complex further leading to problems in meiotic progression. Here we observed that two core components of the pho repressive complex are required for female fertility. Further, we show that specific germline dSfmbt depletion leads to an abnormal increase of Corolla and defective synaptonemal complex morphology in the oocyte chromatin throughout development. Chapter III is an independent chapter where we reveal Nine Teen Complex Protein Salsa as being particularly rate limiting for efficient splicing of short proximal introns and dorsoventral patterning of the Drosophila egg. We observed that, upon specific germline depletion of Salsa, Gurken transcript is poorly spliced leading to an abnormal localization, subsequentially leading to defects in the eggshell dorsoventral patterning and female fertility. Further we show that ectopic Gurken expression can suppress the dorsal ventral patterning defects after Salsa depletion. Our work aims to mechanistically understand our observations.