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In a recent study, Steven J. Pittler, PhD, examined rod cell proteins GARP1 and GARP2 to learn how they function in retinal degeneration, using optical coherence tomography, or OCT. First, Pittler and fellow UAB researcher Marci DeRamus, PhD, carefully aligned mouse OCT imaging with mouse microscopic histologic imaging to propose the uniform mouse OCT nomenclature, which they adopted in their experiments.

The UAB researchers then bred knockout mice that lacked a rod protein called cGMP-gated cation channel beta-subunit and the GARP proteins, which are all encoded by the same gene. The beta-subunit is part of the membrane channel that fires the electrical signal in rod cells in response to light. Then, they bred the knockout mice with three more strains of mice expressing either just GARP1 alone, just GARP2 alone, or both GARP1 and GARP2.

They followed retinal degeneration in these strains at three and 10 weeks, using OCT and light and transmission microscopy to measure thinning of the outer nuclear layer, which contains the cell bodies of the rods and cones. They also measured thinning of the full retinal thickness. They measured functional loss by electroretinography.