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E.S. Lee, J.G. Flannery; Characterization of Rhodopsin Knockout Mice: A Microscopic Analysis . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2856.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Rhodopsin Knockout mice have been previously generated to understand rod opsin function and retinal degenerations (Humphries 1997, Lem 1999). This investigation continues the characterization of the rhodopsin null mice to understand how trafficking of outer segment proteins and membranes are affected by the loss of rhodopsin synthesis. Methods: Postnatal day 8, 20, 30, and 45 rhodopsin null mice retinas were prepared for transmission and scanning electron microscopy. Additionally, retinas were prepared for immunoelectron microscopy using primary antibodies against Rom-1. Wild type mice served as controls. Results: Accumulation of membranes at the distal tip of the connecting cilium commenced late in photoreceptor development and continued throughout adulthood. In a subset of photoreceptors, membranes accumulated around an electron dense core in the inner segment or projected from the inner segment to create a membrane "tower". Rom-1 localized exclusively to these newly synthesized membranes but was not detected in lateral inner segment membranes. Conclusions: Biosynthesis of new membranes destined for the outer segment continues even in the absence of rhodopsin. However, mislocalized membranes are also found in photoreceptors and may contribute to apoptosis of these cells. Our results also suggest Rom-1 has alternate sorting and trafficking events independent of rhodopsin.
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