Recycling polarity mechanisms controlling stem cell polarity in consecutive divisions in the developing Drosophila central nervous system. (360G-Wellcome-100031_Z_12_Z)

Asymmetrically dividing Drosophila neuroblasts keep the cell polarity and division axis robustly oriented over many cell cycles. How positional information is generated to repeatedly polarise theses cells in an oriented manner between different cycles is unknown. As the mRNA of key asymmetry genes is apically localised, I aim to study if localised transcripts are polarity landmarks in neuroblasts. I further aim to study the level of mRNA localisation in these stem cells with the aim to identify centrosomally localised transcripts that I suspect to carry cell fate information. Cell fate information is also transmitted by differential segregation of cortex bound determinants from neuroblasts to differentiating daughter cells. How the mitotic cortex gets spatially organised into compartments that carry determinants remains unknown. I hypothesise that lateral diffusion barriers or a specific distribution of phospholipids organise membrane asymmetries in mitosis. Asymmetries of the me mbrane can also be detected in interphase at the basal neuroblast cell pole, evident with a specific structure overlying the last-born daughter cell. I plan to test if daughter cells send signals to the stem cell contributing to stem cell polarity to understand how the orientation of stem cell polarity is maintained from one cell cycle to the next.