AXONAL MIGRATION OF PROTEINS IN THE CENTRAL NERVOUS SYSTEM AND PERIPHERAL NERVES AS SHOWN BY RADIOAUTOGRAPHY

Demonstration of axonal flow by the movement of tritium-labeled protein in mature optic nerve fibers

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EVIDENCE FOR THE EXISTENCE OF FOUR TYPES OF RIBONUCLEOPROTEIN IN THE NERVE CELLS OF THE CEREBELLUM IN THE ADULT CAT

In Helly-fixed cerebella, the toluidine blue – molybdate staining procedure reveals the existence of four distinct types of ribonucleoprotein in both the Purkinje cells of the vermian zone and the multipolar ganglion cells of the fastigial nucleus. These four types of ribonucleoprotein are found in, respectively, the ground substance (nucleolar matrix) of the nucleolus, the intranucleolar vacuoles (nucleolini), the intranuclear paranucleolar masses, and the cytoplasmic Nissl bodies. The relevant observational evidence suggests that the two organelles of the nucleolar apparatus, that is, the nucleolus and paranucleolar masses together with their associated chromocenters, are concerned with distinct synthetic activities with regard to the elaboration of neuronal ribonucleic acids or ribonucleoproteins. The significance of the above findings is discussed in the light of current concepts pertaining to cellular ribonucleoprotein metabolism.

Delayed Appearance of Labeled Protein in Isolated Nerve Endings and Axoplasmic Flow

Subcellular fractions of mouse brain were prepared by differential and sucrose density-gradient centrifugation at intervals up to 130 hours after intracerebral injection of C(14)- labeled leucine. The specific activity of the nerve ending fraction continued to rise during this period. Between 2 and 130 hours after injection there was a fivefold rise in the specific activity of the soluble protein prepared by lysing the nerve ending particles with water while the specific activity of the soluble protein from the whole homogenate concomitantly fell almost by a factor of three. The data are interpreted as being consistent with the appearance of protein in nerve endings by axoplasmic flow.