Akt regulates centrosome migration and spindle orientation in the early Drosophila melanogaster embryo

Correct positioning and morphology of the mitotic spindle is achieved through regulating the interaction between microtubules (MTs) and cortical actin. Here we find that, in the Drosophila melanogaster early embryo, reduced levels of the protein kinase Akt result in incomplete centrosome migration around cortical nuclei, bent mitotic spindles, and loss of nuclei into the interior of the embryo. We show that Akt is enriched at the embryonic cortex and is required for phosphorylation of the glycogen synthase kinase-3β homologue Zeste-white 3 kinase (Zw3) and for the cortical localizations of the adenomatosis polyposis coli (APC)–related protein APC2/E-APC and the MT + Tip protein EB1. We also show that reduced levels of Akt result in mislocalization of APC2 in postcellularized embryonic mitoses and misorientation of epithelial mitotic spindles. Together, our results suggest that Akt regulates a complex containing Zw3, Armadillo, APC2, and EB1 and that this complex has a role in stabilizing MT–cortex interactions, facilitating both centrosome separation and mitotic spindle orientation

Quantitative image analysis of chromosome dynamics in early Drosophila embryos

We have developed a method for the automatic quantification of chromosome dynamics in live fluorescent microscopy image sequences of mitosis in Drosophila early embryos. Our approach utilises the Fast Level Sets method to perform image segmentation and tracking and incorporates the use of intensity information and prior knowledge of the shape of the chromosomes in the images, the method allows us to easily extract biologically relevant parameters. Tracking and measurements from real fluorescent imaging datasets are presented, highlighting the robustness of our techniques. © 2007 IEEE

Quantitative image analysis of chromosome dynamics in early Drosophila embryos

We have developed a method for the automatic quantification of chromosome dynamics in live fluorescent microscopy image sequences of mitosis in Drosophila early embryos. Our approach utilises the Fast Level Sets method to perform image segmentation and tracking and incorporates the use of intensity information and prior knowledge of the shape of the chromosomes in the images, the method allows us to easily extract biologically relevant parameters. Tracking and measurements from real fluorescent imaging datasets are presented, highlighting the robustness of our techniques. © 2007 IEEE