Using Expansion Microscopy to Observe Mitochondrial Defects in the Early Embryo of Drosophila melanogaster
Raquel Juliette Tamayo, Madison Raub
Department of Biology
Faculty Supervisor: Blake Riggs
Faithful inheritance of mitochondria during cell division is essential for proper cellular function, yet the mechanisms that control how mitochondria are distributed remain unclear. Unlike chromosomes, which are actively segregated, mitochondria have traditionally been thought to be distributed randomly. However, recent evidence suggests that mitochondrial endoplasmic reticulum contact sites (MERCS) may help organize mitochondria and coordinate their positioning during division. The mitochondrial Rho GTPase Miro is known to regulate mitochondrial trafficking and interactions with the endoplasmic reticulum (ER), but its role during early embryonic development is not well understood. In this study, syncytial embryos of Drosophila melanogaster are used to examine whether Miro influences mitochondrial organization and ER mitochondria proximity during rapid nuclear divisions. Maternal Miro depletion is achieved using a nanos-GAL4–driven RNAi approach, with undriven RNAi embryos serving as controls and a dmiro loss-of-function background used for comparison. Expansion microscopy combined with immunofluorescence labeling of mitochondria (VDAC) and the ER (KDEL receptor) is used to visualize organelle structure, followed by qualitative confocal imaging. We hypothesize that loss of Miro will disrupt mitochondrial distribution and alter ER mitochondria spatial coordination. Understanding these mechanisms will help clarify how mitochondria are inherited during development and may provide insight into mitochondrial dysfunction associated with human disease