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Cell divisions that create daughter cells of different sizes are crucial for the generation of cell diversity during animal development. In such asymmetric divisions, the mitotic spindle must be asymmetrically positioned at the end of anaphase. The mechanisms by which cell polarity translates to asymmetric spindle positioning remain unclear. Here we examine(More)
Polarization of cells by PAR proteins requires the segregation of antagonistic sets of proteins into two mutually exclusive membrane-associated domains. Understanding how nanometer scale interactions between individual PAR proteins allow spatial organization across cellular length scales requires determining the kinetic properties of PAR proteins and how(More)
In the Caenorhabditis elegans zygote, a conserved network of partitioning-defective (PAR) polarity proteins segregates into an anterior and a posterior domain, facilitated by flows of the cortical actomyosin meshwork. The physical mechanisms by which stable asymmetric PAR distributions arise from transient cortical flows remain unclear. We present evidence(More)
Many proteins contain disordered regions of low-sequence complexity, which cause aging-associated diseases because they are prone to aggregate. Here, we study FUS, a prion-like protein containing intrinsically disordered domains associated with the neurodegenerative disease ALS. We show that, in cells, FUS forms liquid compartments at sites of DNA damage(More)
Nuclei in the proliferative pseudostratified epithelia of vastly different organisms exhibit a characteristic dynamics - the so-called interkinetic nuclear migration (IKNM). Although these movements are thought to be intimately tied to the cell cycle, little is known about the relationship between IKNM and distinct phases of the cell cycle and the role that(More)
Asymmetric divisions are crucial for generating cell diversity; they rely on coupling between polarity cues and spindle positioning, but how this coupling is achieved is poorly understood. In one-cell stage Caenorhabditis elegans embryos, polarity cues set by the PAR proteins mediate asymmetric spindle positioning by governing an imbalance of net pulling(More)
Asymmetric cell divisions are essential for the development of multicellular organisms. To proceed, they require an initially symmetric cell to polarize. In Caenorhabditis elegans zygotes, anteroposterior polarization is facilitated by a large-scale flow of the actomyosin cortex, which directs the asymmetry of the first mitotic division. Cortical flows(More)
We visualized a fluorescent-protein (FP) fusion to Rab6, a Golgi-associated GTPase, in conjunction with fluorescent secretory pathway markers. FP-Rab6 defined highly dynamic transport carriers (TCs) translocating from the Golgi to the cell periphery. FP-Rab6 TCs specifically accumulated a retrograde cargo, the wild-type Shiga toxin B-fragment (STB), during(More)
During unequal cell divisions a mitotic spindle is eccentrically positioned before cell cleavage. To determine the basis of the net force imbalance that causes spindle displacement in one-cell Caenorhabditis elegans embryos, we fragmented centrosomes with an ultraviolet laser. Analysis of the mean and variance of fragment speeds suggests that the force(More)
Centrosomes consist of a centriole pair surrounded by pericentriolar material (PCM). Previous work suggested that centrioles are required to organize PCM to form a structurally stable organelle. Here, we characterize SAS-4, a centriole component in Caenorhabditis elegans. Like tubulin, SAS-4 is incorporated into centrioles during their duplication and(More)