Red fluorescent protein exposes brain disorders


Rebecca Pool

Thursday, February 25, 2016 - 16:30

FlicR1: Shining a fluorescent light on the brain [Ahmed Abdelfattah]

Researchers have developed a bright red fluorescent protein voltage indicator to image the electrical activity of neurons using wide-field fluorescence microscopy.

Designed by Ahmed Abdelfattah from the University of Alberta and colleagues, 'FlicR1' is said to have sufficient speed and sensitivity to report single action potentials and voltage fluctuations up to 100 Hz frequencies with wide-field microscopy.

"One issue that conspires to limit our understanding [of neuronal disorders] is our inability to easily visualise communication within populations of neuronal cells at [micron] resolutions,” says Abdelfattah. “[So] we need to turn to optical imaging using fluorescent probes that can change colour or intensity when a particular neuron is activated.”

With this in mind, the researchers used directed protein evolution with rational engineering to screen libraries of thousands of possible variants to develop the new voltage biosensor.

As Abdelfattah points out, FlicR1 translates electrical signals between neurons into fluorescence that can be easily measured using conventional widefield fluorescence microscopy.

"This enables us to 'see messages' as they are relayed through the nervous system," he says. "More importantly, we can see these messages with FlicR1 at the highest temporal resolution possible; a single action potential or 1/1000th of a second.”

And crucially, the indicator is less photo-toxic and has a lower auto-fluorescent background than the equivalent green fluorescent protein-based sensor, while exhibiting similar properties.

“We foresee that FlicR1 and its future progeny can be used to unravel the functional basis of neuronal disorders in more detail and empower us to develop novel treatments," he adds.

Research is published in the Journal of Neuroscience.

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