The new findings are reported by Alexander Gottschalk and colleagues at Goethe-University Frankfurt and at the Max Planck Institute for Biophysical Chemistry, also in Frankfurt.
In their new study, the researchers employed a light-sensitive protein from the green alga Chlamydomonas reinhardtii. This protein, channelrhodopsin-2 (ChR2), sits in cell membranes, where it gates the flow of certain ions from one side of the membrane to the other. Such so-called channel proteins play central roles in the activities of neurons and muscle cells, and while some channel proteins are sensitive to chemicals or electrical signals, ChR2 and its relatives are controlled directly by certain wavelengths of light, making them ideal for remote control in the laboratory.
In their experiments, the researchers took advantage of the light sensitivity of the algal channel protein by introducing expression of a modified form of ChR2 in specific C. elegans neurons and muscle cells. The researchers found that when this form of ChR2 was expressed in muscle cells, blue-light activation of the protein was sufficient to cause strong contraction of the muscle. They found that muscle contraction was simultaneous with light exposure.
The researchers went on to show that expression of the engineered ChR2 in mechanosensory neurons, which respond to touch by activating a reflex that causes worms to back up, was suffic