These OMP-ChR2-YFP (OCY-58) mice express a ChR2(H134R)-EYFP fusion gene from the olfactory marker protein locus (Omp). Mice that are homozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. ChR2(H134R)-EYFP is expressed in all mature olfactory sensory neurons, rendering them light sensitive. Light directed at the olfactory epithelium or the glomeruli can elicit activity in mitral/tufted (M/T) cells of the olfactory bulb and can drive odor guided behavior. These mutant mice thus allow precise, timed delivery of stimuli input to the olfactory system. The Donating Investigator reports that this this targeted mutation creates a null allele. Due to possible olfactory deficits, analysis should be performed in heterozygous mice. The Donating Investigator recommends keeping the strain on the albino B6 background to avoid possible interference by pigmented melanocytes.
The ChR2(H134R)-EYFP fusion protein is composed of a Chlamydomonas reinhardtii-derived channelrhodopsin-2 that harbors a gain-of-function H134R substitution fused in-frame with an enhanced yellow fluorescent protein. The ChR2(H134R) is designed to cause larger stationary photocurrents compared to ChR2.
The bacterial opsins are retinal-binding proteins that combine a light-sensitive domain with an ion channel or pump; providing light-dependent ion transport, membrane potential alteration, and sensory functions to bacteria. This ChR2(H134R) functions as a blue light-driven cation channel that depolarizes the cell and causes action potentials. As such, illuminating ChR2(H134R)-expressing cells with blue light (450-490 nm) leads to rapid and reversible photostimulation of action potential firing activity in these cells.
