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Collective migration is a key feature of the social amoebae Dictyostelium discoideum, where the binding of chemoattractants leads to the production and secretion of additional chemoattractant and the relay of the signal to neighboring cells. This then guides cells to migrate collectively in a head-to-tail fashion. We used mutants that were defective in(More)
Neutrophils express a variety of collagen receptors at their surface, yet their functional significance remains unclear. Although integrins are essential for neutrophil adhesion and migration on 2-dimensional (2D) surfaces, neutrophils can compensate for the absence of integrins in 3-dimensional (3D) lattices. In contrast, we demonstrate that the inhibition(More)
We observe and quantify wave-like characteristics of amoeboid migration. Using the amoeba Dictyostelium discoideum, a model system for the study of chemotaxis, we demonstrate that cell shape changes in a wave-like manner. Cells have regions of high boundary curvature that propagate from the leading edge toward the back, usually along alternating sides of(More)
Neutrophil recruitment to inflammation sites purportedly depends on sequential waves of chemoattractants. Current models propose that leukotriene B(4) (LTB(4)), a secondary chemoattractant secreted by neutrophils in response to primary chemoattractants such as formyl peptides, is important in initiating the inflammation process. In this study we demonstrate(More)
We apply linear stability theory and perform perturbation studies to better characterize, and to generate new experimental predictions from, a model of chemotactic gradient sensing in eukaryotic cells. The model uses reaction-diffusion equations to describe 3(') phosphoinositide signaling and its regulation at the plasma membrane. It demonstrates a range of(More)
This study has redesigned the Rey 15-item Visual Memory Test (1964) by introducing more complex figures and by increasing internal logic and pattern redundancy. Standardized administrative procedures and rules for a simple qualitative scoring system were established. Performance on the original Rey continued to be significantly contaminated by ability(More)
During cell migration, cell-substrate binding is required for pseudopod anchoring to move the cell forward, yet the interactions with the substrate must be sufficiently weak to allow parts of the cell to de-adhere in a controlled manner during typical protrusion/retraction cycles. Mammalian cells actively control cell-substrate binding and respond to(More)
The physics of lipid bilayers has been studied for varying lipid and protein constituents. The effects of molecules that transiently associate with the bilayer is a new area of research. In this work, we focus on two proteins involved in vesicle trafficking inside cells, Arf1 and ArfGAP1. Research has suggested that these proteins may act as curvature(More)
This paper evaluates SLEFEs (Subdividable Linear Efficient Function Enclosures) as an optimal method to bound functions. It investigates the extension to all degrees of the degree three proof in [1] showing that SLEFE widths are at most 7% larger than the widths of the smallest possible linear enclosure. This paper shows that such an extension may be(More)