Observers show small but systematic deviations from equal weighting of all elements when asked to localize the center of an array of dots. Counter-intuitively, with small numbers of dots drawn from a Gaussian distribution, this bias results in subjects overweighting the influence of outlier dots - inconsistent with traditional statistical estimators of central tendency. Here we show that this a...

Asymmetric distribution of proteins and other molecules within cells leads to cell polarization. One of the most studied examples occurs in epithelial cells that polarize to form apical and basolateral surfaces (Nelson, 2003). Although we know much about directed protein trafficking after cells are polarized, less is known about the initial mechanisms that lead to polarization. Genetic and bioc...

In this issue of Neuron, Xie et al. (2013) identified protein phosphatase 4c (PP4c) as a new component in the regulation of spindle orientation during mammalian neurogenesis. Importantly, their findings uncovered a novel and critical temporal aspect of the regulation of spindle orientation during neurogenesis.

We extend the analytical theory of propagating concentration polarization (CP) to describe and compare the effects of constant-voltage versus constant-current conditions on the transient development of CP enrichment and depletion zones. We support our analysis with computational and experimental results. We find that at constant voltage, enrichment and depletion regions spread as t(1/2) as oppo...

RNA interfering (RNAi) screening strategies offer the potential to elucidate the signaling pathways that regulate integrin and adhesion receptor-mediated changes in T lymphocyte morphology. Of crucial importance, however, is the definition of key sets of parameters that will provide accurate, quantitative, and nonredundant information to flag relevant hits in such assays. In this study, the aut...

Background: It is important to set up hospitals, since they play a key role in providing health care services based on the budget allocated to the health sector. Objective:  This study evaluated factors militating against the establishment of hospitals in Iran. It also emphasized the importance of health care services. Methods: This...

We demonstrate experimentally an optical process in which the spin angular momentum carried by a circularly polarized light beam is converted into orbital angular momentum, leading to the generation of helical modes with a wave-front helicity controlled by the input polarization. This phenomenon requires the interaction of light with matter that is both optically inhomogeneous and anisotropic. ...

Coordinated cell polarization and mitotic spindle orientation are thought to be important for epithelial morphogenesis. Whether spindle orientation is indeed linked to epithelial morphogenesis and how it is controlled at the molecular level is still unknown. Here, we show that the NuMA- and Galpha-binding protein LGN is required for directing spindle orientation during cystogenesis of MDCK cell...

Mitotic spindle orientation is used to generate cell fate diversity and drive proper tissue morphogenesis. A complex of NuMA and dynein/dynactin is required for robust spindle orientation in a number of cell types. Previous research proposed that cortical dynein/dynactin was sufficient to generate forces on astral microtubules (MTs) to orient the spindle, with NuMA acting as a passive tether. I...

BACKGROUND Asymmetric cell divisions are involved in the divergence of the first two lineages of the pre-implantation mouse embryo. They first take place after cell polarization (during compaction) at the 8-cell stage. It is thought that, in contrast to many species, spindle orientation is random, although there is no direct evidence for this. METHODOLOGY/PRINCIPAL FINDINGS Tubulin-GFP and li...