Development of rapid axonal flow in the chick embryo

Abstract

SUMMARYThe development of axonal transport in the optic nerve of the developing chick has been investigated. Following monocular injection of radioactive fucose and proline, the specific activity of protein from paired optic lobes was determined in chick embryos and new-hatched chicks. In addition, the magnitude of the acid soluble precursor pool within lobes was assayed. The specific activity of protein in the optic lobe contralateral to (and innervated by) the injected eye relative to that of protein within the corresponding ipsilateral lobe (not innervated by the injected eye) was used as an index of axonal flow. In embryonic chicks from 8-12 days of age, four hours after injection of 3 H -f~~a~e into a single eye, this ratio was somewhat above unity. In the 13-day incubated embryo the ratio rose abruptly to over 10, and remained high throughout the period studied (up to one day after hatch). No similar sharp rise was found for the corresponding ratio for acid soluble radioactivity which remained under 2 in all ages of chicks examined. Parallel experiments with 14C-proline resulted in a smaller and more gradual development of asymmetry of specific activity of protein from paired optic lobes.These data suggest that, at the 13th day of incubation, specialized mechanisms develop for the rapid distal transport of glycoprotein synthesized within the retinal ganglion cells to terminations in the optic tectum. This phenomenon follows the major development of cerebral oxidative metabolism, but precedes the appearance of spontaneous or evoked potentials within the chick brain.

Electrophoretic Characterization of Leucine‐, Glucosamine‐ and Fucose‐labelled Proteins Rapidly Transported in Frog Sciatic Nerve

“…GLYCOPROTEINS have been implicated as important structural and functional components of cell membranes (SPIRO, 1969) and have attracted special interest in neurobiology because of their possible role in the regulation of synaptic function (BARONDES, 1968). Rapid axonal transport in various optic systems has been demonstrated for fucose-labelled glycoproteins (BONDY, 1971 ;BONDY and MADSEN, 1971 ;KARLSSON and SJ~STRAND, 1971b;FORMAN et al, 1972) and for glucosamine-labelled material . Radioactive fucose can be used to label specifically brain glycoproteins ( ZATZ and BARONDES, 1970;QUARLES and BRADY, 1971 ;GLASGOW et al, 1972;MARGOLIS and MARGOLIS, 1972).…”

Axonal Transport of Glycoconjugates in the Rat Visual System

“…It has long been known that glycoproteins are transported rapidly. The time course of this process, as well as the molecular-weight distribution of the transported fucosylated glycoproteins, has been described in some detail for several pathways in a number of species (Bondy and Madsen, 1971;Forman et al, 1971;Karlsson and Sjostrand, 1971;McEwen et al, 1971;Edstrom and Mattsson, 1972;Ochs, 1972;Ambron et al, 1974; Padilla and Morell, 1 9 8 0~; Roger et al, 1980;Toews et al, 1982;Goodrum and Morell, 1982;Stone et al, 1983). Although less is known about the transport of other biologically significant glycoconjugates, it is clear that gangliosides (Forman and Ledeen, 1972;Rosner and Merz, 1982) and glycosoaminoglycans (GAGs) (Elam and Agranoff, 1971;Elam and Peterson, 1976;Goodrum et al, 1979;Elam, 1982) are also transported from the cell body to nerve endings.…”

Biochemical Maturation of the Non-Innervated Chick Optic Lobe

“…The maturation of blood-brain barrier is not completely prevented by deafferentation of the chick optic lobe [37]. However, other maturation processes such as the formation of myelin cerebrosides and the appearance of 2': 3' -cyclic nucleotide phosphohydrolase are selectively inhibited [2] by optic lobe deafferentation.…”