We report an imaging method for fast, sensitive analysis of the orientation of fluorescent molecules by employing a liquid-crystal based universal polarizer in the optical path of a wide-field light microscope. We developed specific acquisition and processing algorithms for measuring the anisotropy and for correcting artifacts caused by fluorescence bleaching, background light, and differential...

The final step of cytokinesis is abscission when the intercellular bridge (ICB) linking the two new daughter cells is broken. Correct construction of the ICB is crucial for the assembly of factors involved in abscission, a failure in which results in aneuploidy. Using live imaging and subdiffraction microscopy, we identify new anillin-septin cytoskeleton-dependent stages in ICB formation and ma...

Septin-family proteins assemble into rod-shaped heteromeric complexes that form higher-order arrangements at the cell cortex, where they serve apparently conserved functions as diffusion barriers and molecular scaffolds. There are 13 confirmed septin paralogues in mammals, which may be ubiquitous or tissue specific. Septin hetero-oligomerization appears homology subgroup directed, which in turn...

The mechanisms that couple cell cycle progression with the organization of the peripheral cytoskeleton are poorly understood. In Saccharomyces cerevisiae, the Swe1 protein has been shown previously to phosphorylate and inactivate the cyclin-dependent kinase, Cdc28, thereby delaying the onset of mitosis. The nim1-related protein kinase, Hsl1, induces entry into mitosis by negatively regulating S...

The recent observation of GTP-promoted polymerization of a single septin polypeptide suggests that this protein has tubulin-like biochemical properties. This model cannot, however, explain the GTP-biochemistry of heteromeric septin complexes from cytosol.

Mammalian septins are a family of guanosine triphosphate-binding proteins thought to play a role in a number of key cellular processes, such as cytokinesis, protein scaffolding and vesicle trafficking. Although their precise functions remain to be determined, electron microscopy has shown septin filament formation in vitro and a role as a cytoskeletal polymer has been proposed. Here, we present...

Septins are a family of eukaryotic GTP-binding proteins that associate into linear rods, which, in turn, polymerize end-on-end into filaments, and further assemble into other, more elaborate super-structures at discrete subcellular locations. Hence, septin-based ensembles are considered elements of the cytoskeleton. One function of these structures that has been well-documented in studies condu...

Septins are filament-forming proteins important for organizing the cortex of animal and fungal cells. In mammals, 13 septin paralogues were recently shown to assemble into core heterohexamer and heterooctamer complexes, which serve as building blocks for apolar filamentous structures that differ among cell types. To determine how tissue-specific septin paralogue expression may shape core hetero...

Hyphal growth of Candida albicans is implicated as an important virulence factor for this opportunistic human pathogen. Septin proteins, a family of cytoskeletal elements that regulate membrane events and are important for proper morphogenesis of C. albicans, were examined for their role in tissue invasion and virulence in the mouse model of systemic infection. In vitro, septin mutants are only...

BACKGROUND Septins are well known to form a boundary between mother and daughter cells in mitosis, but their role in other morphogenic states is poorly understood. RESULTS Using microfluidics and live-cell microscopy, coupled with new computational methods for image analysis, we investigated septin function during pheromone-dependent chemotropic growth in yeast. We show that septins colocaliz...