... be influenced by the size, composition or dynamics of contacts between membranes. The initiation of Notch signalling in the Drosophila embryo occurs during cellularization, when lateral cell membranes and adherens junctions are first being deposited, allowing us to investigate the importance of membrane...

...Anja Schmidt; Zhiyi Lv; Jörg Großhans ABSTRACT Canoe/Afadin and the GTPase Rap1 specify the subapical domain during cellularization in Drosophila embryos. The timing of domain formation is unclear. The subapical domain might gradually mature or emerge synchronously with the basal and lateral...

..., regulated by different zygotic genes. We identify the gene dunk , which we show is transiently transcribed when cellularization starts and functions to maintain cortical myosin during the flow phase. The subsequent direct myosin recruitment, however, is Dunk-independent but requires Slam. The Slam-dependent...

... endogenous localization and function. Endogenous Rab8 displays partial coincidence with Rab11 and the Golgi, and this colocalization is enriched during the fast phase of cellularization. When Rab8 function is disrupted, furrow formation in the early embryo is completely abolished. We also demonstrate...

... cleavage patterns. Data from the mouse suggest that cellular morphogenesis and molecular signaling at the cleavage stage play important roles in lineage specification at later (blastula and gastrula) stages. Very little is known, however, about cleavage-stage chick embryos, owing to their poor...

...Mala Murthy; Rita O. Teodoro; Tamara P. Miller; Thomas L. Schwarz Cellularization of the Drosophila embryo is the process by which a syncytium of ∼6000 nuclei is subdivided into discrete cells. In order to individualize the cells, massive membrane addition needs to occur by a process...

... the cleavage divisions terminate, transcription increases and the blastoderm cellularizes. Embryos mutant for grp , which encodes Checkpoint kinase 1 (Chk1), are DNA-replication-checkpoint defective and fail to cellularize, gastrulate or to initiate high-level zygotic transcription at the MBT. The mnk (also...

... assays. We demonstrate that the Drosophila scraps gene, identified as a gene involved in cellularization, encodes Anillin. We characterize defects in cellularization,pole cell formation and cytokinesis in a series of maternal effect and zygotic anillin alleles. Mutations that result in amino acid changes...

...Amy Shaub Maddox; Bianca Habermann; Arshad Desai; Karen Oegema Anillins are conserved proteins that are important for stabilizing and remodeling the actin cytoskeleton. Anillins have been implicated in cytokinesis in several systems and in cellularization of the syncytial Drosophila embryo. Here...

...Jeffrey H. Thomas; Eric Wieschaus Formation of the Drosophila cellular blastoderm involves both membrane invagination and cytoskeletal regulation. Mutations in src64 and tec29 reveal a novel role for these genes in controlling contraction of the actin-myosin microfilament ring during this process...

... fail to transit off the midgut into the mesoderm. We show that slam is required at this stage in parallel to HMG Coenzyme A reductase , a previously identified germ cell migration gene. Removal of both zygotic and maternal slam results in an earlier defect: a failure to form a cellular blastoderm...

... zygotically driven AP asymmetry in the embryo. The second process is the generation of a fine-scale pattern in the actin/myosin array during cellularization. We find three domains of different yolk stalk diameters as well as depths of cellularization along the AP axis. These domains are established under...

... (AT-hook) motif and a domain with similarity to the human fragile X mental retardation FMR2 protein and the AF4 proto-oncoprotein. Embryos lacking maternal lilli expression show specific defects in the establishment of a functional cytoskeleton during cellularization, and exhibit a pair-rule segmentation...

... for Diaphanous and analyzed three cell-cycle-regulated actin-mediated events during embryogenesis: formation of the metaphase furrow, cellularization and formation of the pole cells. In dia embryos, all three processes are defective. Actin filaments do not organize properly to the metaphase and cellularization...

...Paul E. Young; Thomas C. Pesacreta; Daniel P. Kiehart ABSTRACT Dramatic changes in the localization of conventional non-muscle myosin characterize early embryogenesis in Drosophila melanogaster . During cellularization, myosin is concentrated around the furrow canals that form the leading margin...

...Lesilee Simpson; Eric Wieschaus Cellularization of the Drosophila embryo requires the establishment of a hexagonal network of actin and myosin filaments that are interconnected around the nuclei in the cortex of the syncytial blastoderm. This cytoskeletal network provides the framework and possibly...

.... Embryos that lack all X-chromosome material (‘nullo-X embryos’) develop normally to the cycle-14 syncytial blastoderm stage, but fail to partition their nuclei to single cells during cellularization. The cellularization defects can first be detected in the abnormal distribution of cortical actin...