Upstream regulation of the COC by the mitotic program
A centrosome exists in previous stages, but the COC only forms and functions at the onset of meiosis. What regulate COC formation and/or activation? What determines its cellular position upstream to symmetry breaking?
We found that the COC localizes adjacent to the cytoplasmic bridges that connect sister-oocytes during their last division, probably prior to its activity as a COC (left panel in the figure below). The polarity axis of the oocyte is thus perpendicular to the plane of the last mitotic division in the germline cyst (right panel).
What are the mechanisms that position the centrosome and activate it as a COC?
We are investigating the division patterns that construct the germline cyst and how features of the cyst, such as the cytoplasmic bridges and other cytokinesis and cell-division machinery could regulate the COC by determining its position. We have developed protocols for ovarian culturing and live time-lapse imaging in 4-dimensional recordings, where we can trace cysts at different stages (left panel in the figure below) and monitor mitotic progression (right panel) to address these questions.
We are combining a genetic approach by generating CRISPR/Cas9 mutants with experiments in cultured gonads to investigate how the COC is positioned in the cyst.