Local translation of certain mRNAs at synapses in response to activation critically contributes to asymmetric cell polarity and synaptic plasticity (Kiebler and DesGroseillers, 2000; Steward and Schuman, 2001; St Johnston, 2005). The double-stranded RNA-binding protein Staufen has been implicated both in dendritic RNA transport and translational regulation (Tang et al., 2001; Kim et al., 2005)....

In order for eukaryotic cells to function properly, they must establish polarity. The Drosophila oocyte uses mRNA localization to establish polarity and hence provides a genetically tractable model in which to study this process. The spatial restriction of oskar mRNA and its subsequent protein product is necessary for embryonic patterning. The localization of oskar mRNA requires microtubules an...

The Spire protein, together with the formin Cappuccino and profilin, plays an important role in actin-based processes that establish oocyte polarity. Spire contains a cluster of four actin-binding WH2 domains. It has been shown to nucleate actin filaments and was proposed to remain bound to their pointed ends. Here we show that the multifunctional character of the WH2 domains allows Spire to se...

The establishment of anterior-posterior and dorsal-ventral polarity of the Drosophila egg and embryo depends on the function of the genes gurken, cornichon and Egfr (Drosophila epidermal growth factor receptor homolog). These genes encode components of a signal transduction pathway that transmits information between the germline cells and the somatic follicle cells of the ovary. gurken encodes ...

The reaggregation and subsequent development of a range of disaggregated embryos has been examined: 1. Following complete dissociation embryos from 8-cell to late blastocyst reaggregated and developed to form morphologically normal blastocysts, even when blastomeres of two different developmental stages were present in the reaggregate. 2. Dissociated mid-blastocysts could also reaggregate to fo...

Nuclear pore complexes (NPCs) prepared from Xenopus laevis oocyte nuclear envelopes were studied in "intact" form (i.e., unexposed to detergent) and after detergent treatment by a combination of conventional transmission electron microscopy (CTEM) and quantitative scanning transmission electron microscopy (STEM). In correlation-averaged CTEM pictures of negatively stained intact NPCs and of dis...

In amphibians such as Xenopus laevis, the initial polarity of the oocyte is established during oogenesis to produce animal and vegetal hemispheres with extensive structural and compositional differences. The animal-vegetal polarity ot the egg is reinforced by "Surtace Contraction Waves" (SCWs), occurring immediately prior to each cleavage division (Hara et aI., 1980; Sawai, 1982). These are ins...

Polo kinases are known key regulators of cell divisions. Here we report a novel, non-cell division function for polo kinases in embryonic polarity of newly fertilized Caenorhabditis elegans embryos. We show that polo kinases, via their polo box domains, bind to and regulate the activity of two key polarity proteins, MEX-5 and MEX-6. These polo kinases are asymmetrically localized along the ante...

mRNA localization pathways play a central role in axis determination in Drosophila (St Johnson and NussleinVolhard, 1992). The posterior axis of the embryo is specified by a Nanos (Nos) protein gradient, which is generated from the translation of nos mRNA anchored at the posterior pole (Lasko, 1999). nos mRNA is localized at the pole during oogenesis by a mechanism that depends upon the oskar (...

the wiener polarity index wp(g) of a molecular graph g of order n is the number ofunordered pairs of vertices u, v of g such that the distance d(u,v) between u and v is 3. in anearlier paper, some extremal properties of this graph invariant in the class of catacondensedhexagonal systems and fullerene graphs were investigated. in this paper, some new bounds forthis graph invariant are presented....