Selective Delivery

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Science  01 Nov 2013:
Vol. 342, Issue 6158, pp. 537
DOI: 10.1126/science.342.6158.537-a

In an extremely elongated nerve cell, the nucleus is a considerable distance from the growing tip of the axon. Baraban et al. have used zebrafish embryos to show that some messenger RNAs (mRNAs) manage to find their way to the axon tip and that the machinery that transports them there is selective. The authors focused on zebrafish mRNAs that are orthologous to mRNAs that had previously been identified in axons of neurons cultured from rat, mouse, and frog. Of the three mRNAs studied, the one encoding a tubulin variant was the mRNA most effectively delivered into axons of the optic, cranial, and posterior lateral-line nerves in the developing zebrafish embryo. Transport into axons depended on an intact microtubule system and was discriminatory; some mRNA types were transported with more variability, whereas others were not transported at all. Using a reporter system with a membrane-bound fluorescent protein, the authors narrowed down the element required for transport of the tubulin mRNA to a 37-nucleotide portion of the 3′ untranslated region. This selective delivery of mRNA molecules to the axon could facilitate axon guidance in response to changing developmental conditions.

J. Neurosci. 33, 15726 (2013).

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