Precise optical control of gene expression in C elegans using improved genetic code expansion and Cre recombinase

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Precise spatiotemporal control of gene expression is challenging, especially in cells without specific promoters.
• Targeting individual neurons within symmetric pairs is difficult for dissecting neural circuits.

Purpose of the Study:

• To develop an improved genetic code expansion system for optically controlling gene expression in Caenorhabditis elegans.
• To dissect the individual contributions of mechanosensory neurons (PLML/PLMR) to the C. elegans touch response circuit.

Main Methods:

• Developed a photoactivatable Cre recombinase using an improved genetic code expansion system.
• Used laser activation to target Cre in single neurons within a bilaterally symmetric pair.
• Studied the touch response circuit in freely moving C. elegans.

Main Results:

• Successfully switched on optogenetic channel expression in targeted neurons via laser activation.
• Revealed distinct and synergistic roles for the PLML/PLMR mechanosensory neurons in the touch response.
• Demonstrated the ability to break neuron pair symmetry for individual neuron analysis.

Conclusions:

• Genetic code expansion combined with optical targeting offers a powerful method for precise gene control.
• This system enables the dissection of behavioral outputs from individual neurons that are otherwise difficult to target genetically.
• The study provides new insights into the functional roles of specific neurons in the C. elegans touch response circuit.