title: Neutron scattering from myelin revisited: bilayer asymmetry and water-exchange kinetics.
abstract: Rapid nerve conduction in the central and peripheral nervous systems (CNS and PNS, respectively) of higher vertebrates is brought about by the ensheathment of axons with myelin, a lipid-rich, multilamellar assembly of membranes. The ability of myelin to electrically insulate depends on the regular stacking of these plasma membranes and on the presence of a number of specialized membrane-protein assemblies in the sheath, including the radial component, Schmidt-Lanterman incisures and the axo-glial junctions of the paranodal loops. The disruption of this fine-structure is the basis for many demyelinating neuropathies in the CNS and PNS. Understanding the processes that govern myelin biogenesis, maintenance and destabilization requires knowledge of myelin structure; however, the tight packing of internodal myelin and the complexity of its junctional specializations make myelin a challenging target for comprehensive structural analysis. This paper describes an examination of myelin from the CNS and PNS using neutron diffraction. This investigation revealed the dimensions of the bilayers and aqueous spaces of myelin, asymmetry between the cytoplasmic and extracellular leaflets of the membrane, and the distribution of water and exchangeable hydrogen in internodal multilamellar myelin. It also uncovered differences between CNS and PNS myelin in their water-exchange kinetics.
authors.affiliation: Biology Department, Boston College, Chestnut Hill, MA 02467, USA.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Denninger
authors.affiliation: Institut Laue-Langevin (ILL), CS 20156, F-38042 Grenoble CEDEX 9, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Demé
authors.affiliation: Institut Laue-Langevin (ILL), CS 20156, F-38042 Grenoble CEDEX 9, France.
authors.forename: Viviana
authors.initials: V
authors.lastname: Cristiglio
authors.affiliation: European Synchrotron Radiation Facility (ESRF), CS 40220, F-38043 Grenoble CEDEX 9, France.
authors.forename: Géraldine
authors.initials: G
authors.lastname: LeDuc
authors.affiliation: NOVA Scientific Inc., Sturbridge, MA 01566, USA.
authors.forename: W Bruce
authors.initials: WB
authors.lastname: Feller
authors.affiliation: Biology Department, Boston College, Chestnut Hill, MA 02467, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Kirschner
mesh_terms: D000818:Animals; D002490:Central Nervous System / Q000737:chemistry; D041961:Deuterium Exchange Measurement; D007700:Kinetics; D008810:Mice, Inbred C57BL; D009186:Myelin Sheath / Q000737:chemistry*; D033363:Neutron Diffraction; D017933:Peripheral Nervous System / Q000737:chemistry; D051381:Rats; D011916:Rats, Inbred F344; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D014867:Water
keywords: myelin; neutron scattering