Switching modes of myelination

Switching myelination on and off

Schwann cells are remarkably plastic cells that can both form and stably maintain myelin sheaths around axons and also rapidly dedifferentiate upon injury. New findings (Parkinson, D.B., A. Bhaskaran, P. Arthur-Farraj, L.A. Noon, A. Woodhoo, A.C. Lloyd, M.L. Feltri, L. Wrabetz, A. Behrens, R. Mirsky, and K.R. Jessen. 2008. J. Cell Biol. 181:625-637) indicate that the transition between these di...

Switching of Swimming Modes in Magnetospirillium gryphiswaldense.

The microaerophilic magnetotactic bacterium Magnetospirillum gryphiswaldense swims along magnetic field lines using a single flagellum at each cell pole. It is believed that this magnetotactic behavior enables cells to seek optimal oxygen concentration with maximal efficiency. We analyze the trajectories of swimming M. gryphiswaldense cells in external magnetic fields larger than the earth's fi...

Sliding modes in intersecting switching surfaces

When a ow, discontinuous across a switching surface, pointsìnward' so one cannot leave, it induces a unique ow within the surface, called the sliding mode. When several such surfaces intersect, one would seek a ow within the intersection, but some diiculties arise. We explore here the extent of the ambiguity involved in this situation and then show that for a certain form of`natural mechanism f...

Myelination

Feltri et al. (2001)(this issue) succeed in disrupting beta 1 integrin specifically in Schwann cells, and in so doing, demonstrate that it is required for normal myelination. Their results reveal that signaling by an extracellular matrix receptor plays a key role in the differentiation of myelinating Schwann cells.

Kinetic switching between two modes of bisurea surfactant self-assemblyw