Observations on the disassembly of isolated mammalian neurofilaments.

Abstract

Intact mammalian neurofilaments were separated by centrifugation of osmotically shocked, desheathed segments of rat peripheral nerve. Neurofilament-rich supernates were incubated in different media with varying dilutions or dialysis of samples. Neurofilaments attached to C-Formvar-coated grids were exposed to similar incubations. The relative preservation or disruption of neurofilaments during different incubational conditions was monitored through periodic examinations of neurofilaments by negative staining techniques and EM observation. Maximum structural stability of neurofilaments was manifested during incubation in isotonic NaCl or KCl. Decreasing salinity of incubational media led to increasing disruption of neurofilaments, especially in solutions less than 0.01 M. Hypertonic saline solutions were less disruptive to mammalian neurofilaments. Additional studies examined neurofilamentous alterations effected by pH, protein denaturants, mitotic spindle inhibitors, reducing agents and freeze-thawing procedures.