Localization and Active Transport Sympathetic Neurons in Culture

In neurons, the establishment and maintenance of distinct somatic, dendritic, and axonal domains has long been known to rely on regulated traffic of organelles and proteins. More recently, the local targeting of specific mRNAs has also been demonstrated, at least in dendrites, to provide a local supply of specific proteins. Here we set out to test directly for the presence of mRNA in axons of cultured chick sympathetic neurons, to examine their distribution during axonal outgrowth, to determine the reliance of this distribution on specific cytoskeletal elements, and to assess whether the axonal and somatic mRNA complements differ. Using fluorescent in situ hybridization, we found that sympathetic axons do contain poly(A+) mRNA along their length in a pattern that changes gradually as axons elongate, from an evenly dispersed punctate distribution with strong growth cone staining to a distribution focused at