Dendritic membrane from insect olfactory hairs: isolation method and electron microscopic observations

Sensory hairs from antennae of male saturniid moths (Antheraea polyphemus) were separated while deep-frozen by shaking antennal branches with glass beads. The hairs were collected through their differential adhesion to the surface of a petri dish. The yield, determined by the length of the isolated hair fragments, was about 38% of the estimated total hair length per antenna. The dendritic membrane was separated from the hair fragments by centrifugation through Sephadex and further purified by ultracentrifugation in sucrose buffers. Transmission electron microscopy was used to monitor the steps of the hair and membrane isolation and to investigate the membrane pellet. Some membrane vesicles bound cationized ferritin, thus indicating a negatively charged cell surface coat. Negatively stained membrane vesicles exhibited a pattern of repetitive substructures irregularly distributed over the vesicle surface. The units had a diameter of about 3 nm and a maximal density of 30,000/micron2.