Axonal Influences on Schwann Cell Gene Expression

The aim of these studies was to investigate some of the ways in which the axon influences Schwann cell gene expression

Preparation of purified myelin from ox intradural spinal roots by rate-isopycnic zonal centrifugation

1. 1. Ox peripheral nerve myelin membranes were isolated by rate-isopycnic zonal centrifugation. A method is described for the Beckman size 14 zonal rotor. The isolated membranes had the same isopycnic banding density as 15.2% sucrose (w/w). On the basis of studies with twelve marker enzymes and electron microscopy, at least 99% of the fraction consisted of myelin membranes. The electron micrographs showed the typical myelin lamellar rings and vesicles derived by peeling off from these lamellae. 2. 2. The enzyme, 2′,3′-cyclic nucleotide-3′-phosphohydrolase, reported to be closely associated with central nervous system myelin, was shown not to be associated with the peripheral nerve myelin. 3. 3. A membrane fraction which had the same isopycnic banding density as 17.6% sucrose (w/w) was shown to have high specific activity of 5′-nucleotidase and 2′,3′-cyclic nucleotide-3′-phosphohydrolase. A similar fraction was isolated from ox spinal cord. This fraction of the spinal cord membranes banding at 17.6% (w/w) contained no basic protein. 4. 4. The disc electrophoresis pattern of the peripheral nerve myelin proteins was different from that of the spinal cord myelin