Learn More
During microtubule depolymerization, the central, juxtanuclear Golgi apparatus scatters to multiple peripheral sites. We have tested here whether such scattering is due to a fragmentation process and subsequent outward tracking of Golgi units or if peripheral Golgi elements reform through a novel recycling pathway. To mark the Golgi in HeLa cells, we stably(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)
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)
The simplest animal eyes are eyespots composed of two cells only: a photoreceptor and a shading pigment cell. They resemble Darwin's 'proto-eyes', considered to be the first eyes to appear in animal evolution. Eyespots cannot form images but enable the animal to sense the direction of light. They are characteristic for the zooplankton larvae of marine(More)
Asymmetric positioning of the mitotic spindle in C. elegans embryos is mediated by force-generating complexes that are anchored at the plasma membrane and that pull on microtubules growing out from the spindle poles. Although asymmetric distribution of the force generators is thought to underlie asymmetric positioning of the spindle, the number and location(More)
Spindle elongation segregates chromosomes and occurs in anaphase, an essential step in mitosis. Dynein-mediated pulling forces position the spindle, but their role in anaphase is a matter of debate. Here, we demonstrate that dynein is responsible for rapid spindle elongation in the model fungus Ustilago maydis. We show that initial slow elongation is(More)
Precise control over organelle shapes is essential for cellular organization and morphogenesis. During yeast meiosis, prospore membranes (PSMs) constitute bell-shaped organelles that enwrap the postmeiotic nuclei leading to the cellularization of the mother cell's cytoplasm and to spore formation. Here, we analysed how the PSMs acquire their curved(More)
The mechanics of the actin cytoskeleton have a central role in the regulation of cells and tissues, but the details of how molecular sensors recognize deformations and forces are elusive. By performing cytoskeleton laser nanosurgery in cultured epithelial cells and fibroblasts, we show that the retraction of stress fibers (SFs) is restricted to the(More)
Filopodia are thin, spike-like cell surface protrusions containing bundles of parallel actin filaments. So far, filopodial dynamics has mainly been studied in the context of cell motility on coverslip-adherent filopodia by using fluorescence and differential interference contrast (DIC) microscopy. In this study, we used an optical trap and interferometric(More)
We address the problem of segmenting 3D microscopic volumetric intensity images of a collection of spatially correlated objects (such as fluorescently labeled nuclei in a tissue). This problem arises in the study of tissue morphogenesis where cells and cellular components are organized in accord with biological role and fate. We formulate the image model as(More)