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© The Rockefeller University Press, 0021-9525/2002/12/912-b $5.00
The Journal of Cell Biology, Volume 159, Number 6, 912-b-912

Neurons go toward the light

A growth cone extends as directed by a beam of light (circle, top to bottom). Käs/NAS

Like a miniature version of the famous tractor beams of sci-fi lore, beams of light known as optical tweezers have been used to hold and manipulate anything from atoms to cells. Now, Allen Ehrlicher, Josef Käs (Universität Leipzig, Germany), and colleagues show that laser beams can also manipulate a biological process—the growth of an axon.

In their new report, the authors direct axonal growth by focusing a beam of light just ahead of the leading edge of a lamellipodium. Forces of light lower than those used for optical tweezers accelerated growth at the leading edge. Shining the laser on one side of the growth cone caused filopodia to accumulate on that side, thereby initiating as much as a 90° turn of the growth cones.

Although the mechanism behind the effect of light is yet unproven, Ehrlicher describes the group's favorite explanation as "biased monomer diffusion." According to the theory, the electrical field gradient created by the beam, which polarizes the nearby pool of actin monomers, draws the monomers toward the beam's focus, thus favoring polymerization. "In effect, we trick the actin polymerization process," says Ehrlicher.

Whatever the mechanism, Ehrlicher is excited by the possibilities that light control over cell motility may offer. One immediate use will be to construct more precise and longer-lasting in vitro neural networks, in which a small number of neurons are connected in a specific fashion to study neuronal interactions. A long-term goal is to use lasers in vivo to guide the regrowth of severed peripheral nerves in accident victims.

Reference:

Ehrlicher, A., et al. 2002. Proc. Natl. Acad. Sci. USA. 99:16024–16028.[Abstract/Free Full Text]

Nicole LeBrasseur

lebrasn{at}rockefeller.edu

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This Article Full Text (PDF, 294K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Social Bookmarking                            What's this?