Ormed as described [9]. As controls we used ChmFlox littermates and Chm+(WT) mice on the C57Bl6 background. Both females and males were used in this study. Rab27a-mutant (ashen, Rab27ash/ash) mice were purchased from Jackson Laboratory (Bar Harbor, Maine, USA) and bred onto a C57Bl6 background.Transmission Electron MicroscopyEyes were fixed for 90 minutes at room temperature or overnight at 4uC in 2 paraformaldehyde and 2 glutaraldehyde in 0.1M cacodylate buffer. The cornea was cut off to remove theFigure 2. Increased number of phagosomes in ChmFlox, Tyr-Cre+ mice. Frozen sections of eyes from 6-month old ChmFlox, Tyr-Cre+ mice and littermates ChmFlox mice harvested at the indicated times after light onset were immunostained with antibody (RetP1) for rhodopsin and analysed by confocal microscopy. Phase images were used to identify the RPE within the tissue. (A) Overview of the choroid, RPE, and part of the retina in ChmFlox, Tyr-Cre+ sample. Scale bar: 50 mm. The boxed region is magnified in the panel beneath and shows an area of the RPE with overlaying POS, scale bar: 5 mm. (B) Projections of 9 confocal sections. Scale bar: 10 mm. (C) Phagosomes were counted and results were normalised to the control and are presented as mean+/2SEM of 3? observations. *P,0.05. (ONL) Outer nuclear layer, (IS) Inner segment, (OS) Outer segment. doi:10.1371/journal.pone.0057769.gAge-Related Changes in RPE of Choroideremia ModelFigure 3. Accumulation of lipofuscin containing granules in ChmFlox, Tyr-Cre+ mice. (A, B) Electron micrographs of 6-month old ChmFlox, TyrCre+ showing lipofuscin containing granules and melanolipofuscin. B is an enlargement of the area boxed in A. Scale bars: 2 mm (A), 0.5 mm (B). (C ) Retinas of 6-month old ChmFlox mice (black bars), littermates ChmFlox, Tyr-Cre+ (dark grey bars) and 2-year old control mice (light grey bars) were analysed for their content of melanosomes (M), lipofuscin containing granules (LF) and melanolipofuscin (MLF), respectively in the RPE. Melanosomes, lipofuscin containing granules and melanolipofuscin structures were counted and results are shown in the graphs per length of RPE (in mm) (for melanosomes and lipofuscin containing granules) or as a percentage of melanosomes associated with melanolipofuscin. Results are mean+/2SEM of at least 3 observations. *P,0.05, **P,0.01. doi:10.1371/journal.pone.0057769.glens. The eyes were then postfixed in 1.5 potassium ferricyanide and 1 Osmium tetroxide for 2 hours on ice. The eyes were then dehydrated in ethanol (70 , 90 
and absolute) and propylene oxide and transferred to 1:1 propylene oxide:Epon overnight followed by two changes and embedding in Epon. Ultra-thin sections were stained with lead citrate before examination. As for light microscopy, eyecups were cut parallel and adjacent to the optic nerve in order to visualise peripheral and central retina. Samples were viewed on a JEOL 1010 transmission electron microscope (Welwyn Garden City, United Kingdom). Images were taken with a Gatan Orius SC100B charge-coupled device camera and analysed with Gatan Digital Micrograph and Adobe 117793 biological activity Photoshop.controls were analysed. For quantification of basal laminar 78919-13-8 deposits (BLamDs) between 1.5 and 2 mm of length of RPE for each eye were analysed. The length of RPE 
containing BLamDs was measured on 11 ChmFlox, Tyr-Cre+ mice and 14 ChmFlox control mice.StatisticsTo determine the significance of the data the non-parametric Mann and Whitney test was used throughout. A P value.Ormed as described [9]. As controls we used ChmFlox littermates and Chm+(WT) mice on the C57Bl6 background. Both females and males were used in this study. Rab27a-mutant (ashen, Rab27ash/ash) mice were purchased from Jackson Laboratory (Bar Harbor, Maine, USA) and bred onto a C57Bl6 background.Transmission Electron MicroscopyEyes were fixed for 90 minutes at room temperature or overnight at 4uC in 2 paraformaldehyde and 2 glutaraldehyde in 0.1M cacodylate buffer. The cornea was cut off to remove theFigure 2. Increased number of phagosomes in ChmFlox, Tyr-Cre+ mice. Frozen sections of eyes from 6-month old ChmFlox, Tyr-Cre+ mice and littermates ChmFlox mice harvested at the indicated times after light onset were immunostained with antibody (RetP1) for rhodopsin and analysed by confocal microscopy. Phase images were used to identify the RPE within the tissue. (A) Overview of the choroid, RPE, and part of the retina in ChmFlox, Tyr-Cre+ sample. Scale bar: 50 mm. The boxed region is magnified in the panel beneath and shows an area of the RPE with overlaying POS, scale bar: 5 mm. (B) Projections of 9 confocal sections. Scale bar: 10 mm. (C) Phagosomes were counted and results were normalised to the control and are presented as mean+/2SEM of 3? observations. *P,0.05. (ONL) Outer nuclear layer, (IS) Inner segment, (OS) Outer segment. doi:10.1371/journal.pone.0057769.gAge-Related Changes in RPE of Choroideremia ModelFigure 3. Accumulation of lipofuscin containing granules in ChmFlox, Tyr-Cre+ mice. (A, B) Electron micrographs of 6-month old ChmFlox, TyrCre+ showing lipofuscin containing granules and melanolipofuscin. B is an enlargement of the area boxed in A. Scale bars: 2 mm (A), 0.5 mm (B). (C ) Retinas of 6-month old ChmFlox mice (black bars), littermates ChmFlox, Tyr-Cre+ (dark grey bars) and 2-year old control mice (light grey bars) were analysed for their content of melanosomes (M), lipofuscin containing granules (LF) and melanolipofuscin (MLF), respectively in the RPE. Melanosomes, lipofuscin containing granules and melanolipofuscin structures were counted and results are shown in the graphs per length of RPE (in mm) (for melanosomes and lipofuscin containing granules) or as a percentage of melanosomes associated with melanolipofuscin. Results are mean+/2SEM of at least 3 observations. *P,0.05, **P,0.01. doi:10.1371/journal.pone.0057769.glens. The eyes were then postfixed in 1.5 potassium ferricyanide and 1 Osmium tetroxide for 2 hours on ice. The eyes were then dehydrated in ethanol (70 , 90 and absolute) and propylene oxide and transferred to 1:1 propylene oxide:Epon overnight followed by two changes and embedding in Epon. Ultra-thin sections were stained with lead citrate before examination. As for light microscopy, eyecups were cut parallel and adjacent to the optic nerve in order to visualise peripheral and central retina. Samples were viewed on a JEOL 1010 transmission electron microscope (Welwyn Garden City, United Kingdom). Images were taken with a Gatan Orius SC100B charge-coupled device camera and analysed with Gatan Digital Micrograph and Adobe Photoshop.controls were analysed. For quantification of basal laminar deposits (BLamDs) between 1.5 and 2 mm of length of RPE for each eye were analysed. The length of RPE containing BLamDs was measured on 11 ChmFlox, Tyr-Cre+ mice and 14 ChmFlox control mice.StatisticsTo determine the significance of the data the non-parametric Mann and Whitney test was used throughout. A P value.